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  • 1.
    Beyer, Franziska
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gällström, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Deep levels in tungsten doped n-type 3C-SiC2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 15, 152104- p.Article in journal (Refereed)
    Abstract [en]

    Tungsten was incorporated in SiC and W related defects were investigated using deep level transient spectroscopy. In agreement with literature, two levels related to W were detected in 4H-SiC, whereas only the deeper level was observed in 6H-SiC. The predicted energy level for W in 3C-SiC was observed (E-C-0.47 eV). Tungsten serves as a common reference level in SiC. The detected intrinsic levels align as well: E1 (E-C-0.57 eV) in 3C-SiC is proposed to have the same origin, likely V-C, as EH6/7 in 4H-SiC and E7 in 6H-SiC, respectively.

  • 2.
    Beyer, Franziska
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lin, Y.-C.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gällström, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Deep levels in iron doped n- and p-type 4H-SiC2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, 123701-1-123701-5 p.Article in journal (Refereed)
    Abstract [en]

    Deep levels were detected in Fe-doped n- and p-type 4H-SiC using deep level transient spectroscopy (DLTS). One defect level (EC 0.39 eV) was detected in n-type material. DLTS spectra of p-type 4H-SiC show two dominant peaks (EV + 0.98 eV and EV + 1.46 eV). Secondary ion mass spectrometry measurements confirm the presence of Fe in both n- and p-type 4H-SiC epitaxial layers. The majority capture process for all the three Fe-related peaks is multi-phonon assisted. Similar defect behavior in Si indicates that the observed DLTS peaks are likely related to Fe and Fe-B pairs.

  • 3.
    Beyer, Franziska
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Deep levels in hetero-epitaxial as-grown 3C-SiC2010In: AIP Conference Proceedings, Vol. 1292, 2010, 63-66 p.Conference paper (Refereed)
    Abstract [en]

    3C-SiC grown hetero-epitaxially on 4H- or 6H-SiC using a standard or a chloride-based CVD process were electrically characterized using IV, CV and DLTS. The reverse leakage current of the Au-Schottky diodes was  reduced to lower than 10-8 A at -2V by a thermal oxidation step using UV-light illumination at 200oC. The Schottky barrier height of the Ni and Au contacts were determined by IV measurement to be ØB = 0.575  eV and ØB = 0.593 eV, respectively, for a contact diameter of about 150 mm. One dominant DLTS peak was observed in the 3C-epilayers independently of the substrate at about EC0:60 eV which is attributed to W6-level in 3C-SiC. This deep level is thought to be related to an intrinsic defect.

  • 4.
    Eriksson, Jens
    et al.
    CNR IMM.
    Hung Weng, Ming
    CNR IMM.
    Roccaforte, Fabrizio
    CNR IMM.
    Giannazzo, Filippo
    CNR IMM.
    Leone, Stefano
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Raineri, Vito
    CNR IMM.
    Toward an ideal Schottky barrier on 3C-SiC2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, no 8Article in journal (Refereed)
    Abstract [en]

    The electrical characteristics of Au/3C-SiC Schottky diodes were studied as a function of contact area. While the larger diodes were characterized by conventional current-voltage measurements, conductive atomic force microscopy was used to perform current-voltage measurements on diodes of contact radius down to 5 mu m. The results show that the Schottky barrier height increases upon reducing the contact area, and for the smallest diodes the value approaches the ideal barrier height of the system. The results were correlated with defects in the 3C-SiC and an analytical expression was derived to describe the dependence of the barrier height on the defect density.

  • 5.
    Eriksson, Jens
    et al.
    CNR IMM.
    Roccaforte, Fabrizio
    CNR IMM.
    Reshanov, Sergey
    Acreo AB.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Giannazzo, Filippo
    CNR IMM.
    LoNigro, Raffaella
    CNR IMM.
    Fiorenza, Patrick
    CNR IMM.
    Raineri, Vito
    CNR IMM.
    Nanoscale characterization of electrical transport at metal/3C-SiC interfaces2010In: NANOSCALE RESEARCH LETTERS, ISSN 1931-7573, Vol. 6, no 120Article in journal (Refereed)
    Abstract [en]

    In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (Phi(B)) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500 degrees C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900 degrees C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.

  • 6.
    Gueorguiev Ivanov, Ivan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gällström, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Tien Son, Nguyen
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ivády, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Gali, Adam
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Optical properties of the niobium centre in 4H, 6H, and 15R SiC2013In: SILICON CARBIDE AND RELATED MATERIALS 2012, Trans Tech Publications , 2013, Vol. 740-742, 405-408 p.Conference paper (Refereed)
    Abstract [en]

    A set of lines in the photoluminescence spectra of 4H-, 6H-, and 15R-SiC in the near-infrared are attributed to Nb-related defects on the ground of doping experiments conducted with 4H-SiC. A model based on a an exciton bound at the Nb-centre in an asymmetric split vacancy configuration at a hexagonal site is proposed, which explains the structure of the luminescence spectrum and the observed Zeeman splitting of the lines.

  • 7.
    Gällström, Andreas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Magnusson, Björn
    Norstel AB, Norrköping, Sweden.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gali, Adam
    Budapest University of Technology and Economics and Hungarian Academy of Science, Budapest, Hungary .
    Son, Nguyen Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ivanov, Ivan G.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Electronic Configuration of Tungsten in 4H-, 6H-, and 15R-SiC2012In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, 211-216 p.Conference paper (Refereed)
    Abstract [en]

    A commonly observed unidentified photoluminescence center in SiC is UD-1. In this report, the UD-1 center is identified to be tungsten related. The identification is based on (i) a W-doping study, the confirmation of W in the samples was made using deep level transient spectroscopy (DLTS), (ii) the optical activation energy of the absorption of UD-1 in weakly n-type samples corresponds to the activation energy of the deep tungsten center observed using DLTS. The tungsten-related optical centers are reported in 4H-, 6H-, and 15R-SiC. Further, a crystal field model for a tungsten atom occupying a Si-site is suggested. This crystal field model is in agreement with the experimental data available: polarization, temperature dependence and magnetic field splitting.

  • 8.
    Gällström, Andreas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Magnusson, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gali, Adam
    Budapest University of Technology and Economics, Hungary.
    Son Tien, Nguyen
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Optical identification and electronic configuration of tungsten in 4H-and 6H-SiC2012In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 407, no 10, 1462-1466 p.Article in journal (Refereed)
    Abstract [en]

    Several optically observed deep level defects in SiC are still unidentified and little is published on their behavior. One of the commonly observed deep level defects in semi-insulating SiC is UD-1. less thanbrgreater than less thanbrgreater thanThis report suggests that UD-1 is Tungsten related, based on a doping study and previously reported deep level transient spectroscopy data, as well as photo-induced absorption measurements. The electronic levels involved in the optical transitions of UD-1 are also deduced. The transitions observed in the photoluminescence of UD-1 are from a Gamma(C3v)(4), to two different final states, which transform according to Gamma(C3v)(5)circle plus Gamma(C3v)(6) and Gamma(C3v)(4), respectively.

  • 9.
    Gällström, Andreas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Magnusson, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Kordina, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Son, Nguyen Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ivády, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Wigner Research Center for Physics, Hungarian Academy of Sciences, Hungary.
    Gali, Adam
    Wigner Research Center for Physics, Hungarian Academy of Sciences, Budapest Hungary; Department of Atomic Physics, Budapest University of Technology and Economics, Budapest, Hungary.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Materials Modeling and Development Laboratory, NUST “MISIS,” Moscow, Russia; LACOMAS Laboratory, Tomsk State University, Tomsk, Russia.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan G.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Optical properties and Zeeman spectroscopy of niobium in silicon carbide2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 7, 1-14 p., 075207Article in journal (Refereed)
    Abstract [en]

    The optical signature of niobium in the low-temperature photoluminescence spectra of three common polytypes of SiC (4H, 6H, and 15R) is observed and confirms the previously suggested concept that Nb occupies preferably the Si-C divacancy with both Si and C at hexagonal sites. Using this concept we propose a model considering a Nb-bound exciton, the recombination of which is responsible for the observed luminescence. The exciton energy is estimated using first-principles calculation and the result is in very good agreement with the experimentally observed photon energy in 4H SiC at low temperature. The appearance of six Nb-related lines in the spectra of the hexagonal 4H and 6H polytypes at higher temperatures is tentatively explained on the grounds of the proposed model and the concept that the Nb center can exist in both C1h and C3v symmetries. The Zeeman splitting of the photoluminescence lines is also recorded in two different experimental geometries and the results are compared with theory based on phenomenological Hamiltonians. Our results show that Nb occupying the divacancy at the hexagonal site in the studied SiC polytypes behaves like a deep acceptor.

  • 10.
    Henry, Anne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska C.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride based CVD of 3C-SiC on (0001) α-SiC substrates2011In: Materials Science Forum Vols. 679-680 (2011) pp 75-78, Trans Tech Publications Inc., 2011, 75-78 p.Conference paper (Refereed)
    Abstract [en]

    A chloride-based chemical-vapor-deposition (CVD) process has been successfully used to grow very high quality 3C-SiC epitaxial layers on on-axis α-SiC substrates. An accurate process parameters study was performed testing the effect of temperature, surface preparation, precursor ratios, nitrogen addition, and substrate polytype and polarity. The 3C layers deposited showed to be largely single-domain material of very high purity and of excellent electrical characteristics. A growth rate of up to 10 μm/h and a low background doping enable deposition of epitaxial layers suitable for MOSFET devices.

  • 11.
    Henry, Anne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    SiC epitaxy growth using chloride-based CVD2012In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 407, no 10, 1467-1471 p.Article in journal (Refereed)
    Abstract [en]

    The growth of thick epitaxial SiC layers needed for high-voltage, high-power devices is investigated with the chloride-based chemical vapor deposition. High growth rates exceeding 100 mu m/h can be obtained, however to obtain device quality epilayers adjustments of the process parameters should be carried out appropriately for the chemistry used. Two different chemistry approaches are compared: addition of hydrogen chloride to the standard precursors or using methyltrichlorosilane, a molecule that contains silicon, carbon and chlorine. Optical and electrical techniques are used to characterize the layers.

  • 12.
    Henry, Anne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Bergman, Jonas P.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Epitaxial growth on on-axis substrates2012In: Silicon Carbide Epitaxy / [ed] Francesco La Via, Kerala, India: Research Signpost, 2012, 97-119 p.Chapter in book (Refereed)
    Abstract [en]

    SiC epitaxial growth using the Chemical Vapour Deposition (CVD) technique on nominally on-axis substrate is presented. Both standard and chloride-based chemistry have been used with the aim to obtain high quality layers suitable for device fabrication. Both homoepitaxy (4H on 4H) and heteroepitaxy (3C on hexag onal substrate) are addressed.

  • 13.
    Henry, Anne
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Leone, Stefano
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Pedersen, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Growth of 4H-SiC Epitaxial Layers on 4° Off-axis Si-face substrates2009In: Materials Science Forum, Vols. 615-617, Trans Tech Publications , 2009, 81-84 p.Conference paper (Refereed)
    Abstract [en]

    CVD growth of epitaxial layers with a mirror like surface grown on 75 mm diameter 4° off-axis 4H SiC substrates is demonstrated. The effect of the C/Si ratio, temperature and temperature ramp up conditions is studied in detail. A low C/Si ratio of 0.4 and a temperature of 1530 °C is the best combination to avoid step bunching and triangular defects on the epitaxial layers. Using a low growth rate (about 3 µm/h) 6 μm thick, n-type doped epilayers were grown on 75 mm diameter wafers resulting in an RMS value of 0.7 nm and good reproducibility. 20 μm thick epitaxial layers with a background doping in the low 1014 cm-3 were grown with a mirror-like, defect-free surface. Preliminary results when using higher Si/H2 ratio (up to 0.4 %) and HCl addition are also presented: growth rate of 28 μm/h is achieved while keeping a smooth morphology.

  • 14.
    Henry, Anne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Steffano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, S.
    n/a.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Concentrated chloride-based epitaxial growth of 4H-SiC2010In: Materials Science Forum, Vols. 645-648, Transtec Publications; 1999 , 2010, Vol. 645-648, 95-98 p.Conference paper (Refereed)
    Abstract [en]

    A chloride-based CVD process has been studied in concentrated growth conditions. A systematic study of different carrier flows and pressures has been done in order to get good quality epilayers on 8 degrees off and on-axis substrates while using very low carrier flows. Hydrogen chloride (HCl) was added to the standard gas mixture to keep a high growth rate and to get homo-polytypic growth on on-axis substrates. The carrier flow was reduced down to one order of magnitude less than under typical growth condition. By lowering the process pressure it was possible to reduce precursor depletion along the susceptor which improved the thickness uniformity to below 2% variation (sigma/mean) over a 2 diameter wafer.

  • 15.
    Henry, Anne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Li, Xun
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    CVD growth of 3C-SiC on 4H-SiC substrate2012In: Materials Science Forum Vol 711, Trans Tech Publications Inc., 2012, Vol. 711, 16-21 p.Conference paper (Refereed)
    Abstract [en]

    The hetero epitaxial growth of 3C-SiC on nominally on-axis 4H-SiC is reported. A horizontal hot-wall CVD reactor working at low pressure is used to perform the growth experiments in a temperature range of 1200-1500 °C with the standard chemistry using silane and propane as precursors carried by a mix of hydrogen and argon. The optimal temperature for single-domain growth is found to be about 1350 °C. The ramp up-conditions and the gas-ambient atmosphere when the temperature increases are key factors for the quality of the obtained 3C layers. The best pre-growth ambient found is carbon rich environment; however time of this pre-treatment is crucial. A too high C/Si ratio during growth led to polycrystalline material whereas for too low C/Si ratios Si cluster formation is observed on the surface. The addition of nitrogen gas is also explored.

  • 16.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Advances in SiC growth using chloride-based CVD2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Silicon Carbide (SiC) is a wide band-gap semiconductor. Similar to silicon it can be used to make electronic devices which can be employed in several applications. SiC has some unique features, such as wide band-gap, high hardness, chemical inertness, and capability to withstand high temperatures. Its high breakdown electric field, high saturated drift velocity and high thermal conductivity are some of the most important characteristics to understand why SiC has superior electrical properties compared to silicon, and make it very attractive for power devices especially at high voltages and high frequency. The gain in reduced device sizes, reduced cooling requirements, and especially in improved energy efficiency for AC/DC conversion are a very important reasons to keep working in improving the material quality. Yet several issues still limit its full employment in all its potential applications, and many more steps have thus to be done for its complete success.

    The core of an electric device is the epitaxial layer grown on a substrate by chemical vapor deposition (CVD). Gases containing silicon and carbon atoms, such as silane and ethylene, are often used to grow SiC, but limits in high growth rate are given by silicon cluster formation in the gas phase which is detrimental for the epitaxial layer quality. High growth rates are needed to deposit thick layers ( > 100 μm) which are required for high power devices. Chloride-based CVD, which is usually employed in the silicon epitaxial growth industry, is based on the presence of chlorinated species in the gas mixture which prevent the formation of silicon clusters, therefore resulting in very high growth rates. This chloride-based CVD process was first started to be investigated a few years ago and then only at typical growth conditions, without exploring all its full potential, such as its performance at low or high temperature growth. In addition important parameters affecting the epitaxial layer quality in terms of defect formation and electrical characteristics are the substrate orientation and its off-cut angle. Standard processes are run on substrates having an 8° off-cut angle towards a specific crystallographic direction. On lower off-cut angles, such as 4° or almost 0° (also called on-axis) which would be more economical and could resolve problems related to bipolar degradation, many typical issues should be solved or at least minimized. For 4° off-cut angle the main problem is the step-bunching resulting in high roughness of the epi surface whereas for nominally on-axis the formation of 3C inclusions is the main problem.

    In this thesis we discuss and present results on the use of the chloride-based CVD process in a hot-wall reactor to further explore most of the above mentioned topics. Onaxis substrates are used to grow homopolytypic epitaxial layers; detailed experiments on the gas phase composition adopting high contents of chlorine made it possible (Paper 1). Optimization of the on-axis surface preparation prior to the growth in combination with a correct choice of chlorinated precursors and growth conditions were required to reach a growth rate of 100 μm/h of 100% 4H polytype (Paper 2). Substrates with a 4° off-cut angle could be grown free from step-bunching, one of the most common morphological issue and usually detrimental for devices. Both the standard and chlorinated-process were successfully used, but at different growth rates (Paper 3). Also for this off-cut substrate a specific surface preparation and selected growth parameters made the growth possible at rates exceeding 100 μm/h (Paper 4). The benefit of the chlorinated chemistry was tested under unusual growth conditions, such as under a concentrated gas mixture (i.e. at very low carrier gas flow) tested on different off-cut substrates (Paper 5). A great advantage of chloride-based chemistry is the feasibility of growing at very low temperatures (1300 to 1400 °C compared to the 1600 °C standard temperature). At such low temperatures 4H-SiC epitaxial layers could be grown on 8° off-axis substrates (Paper 6), while high quality heteroepitaxial 3C-SiC layers were grown on on-axis 6H-SiC substrates (Paper 7). Finally, the very high growth rates achieved by the chloride-based CVD were applied in a vertical hot-wall reactor configuration, demonstrating the ability to grow very thick SiC layers at higher rates and lower temperatures than what is typically used for bulk growth (Paper 8). This work demonstrated that a new bulk growth process could be developed based on this approach.

    List of papers
    1. Thick homoepitaxial layers grown on on-axis Si-face 6H- and 4H-SiC substrates with HCl addition
    Open this publication in new window or tab >>Thick homoepitaxial layers grown on on-axis Si-face 6H- and 4H-SiC substrates with HCl addition
    Show others...
    2009 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 1, 24-32 p.Article in journal (Refereed) Published
    Abstract [en]

    The homoepitaxial growth of 6H- and 4H-SiC on on-axis substrates has been studied in order to demonstrate the growth of thick, mirror-like epitaxial layers without other polytype inclusions and basal plane dislocations. The study was done in a hot wall reactor using standard precursors silane and ethylene with hydrogen chloride (HCl) addition. The main important process parameters were studied, in particular deposition temperature, and precursor ratios such as C/Si, Cl/Si and Si/H2. The addition of chlorine in the precursor mixture was found to be the key parameter to grow layers at high rate with morphology and thickness similar to epilayers deposited on commonly used off-axis substrates. Two different process conditions were found allowing growth of low-doped (in the low 1014 cm−3 range) 100-μm-thick epitaxial layers at a growth rate of 25 μm/h, 8 times higher than what is achieved without HCl addition. A high concentration of SiCl2 in the gas phase obtained by high Cl/Si and Si/C ratios was fundamental to achieve these results.

    Place, publisher, year, edition, pages
    Elsevier, 2009
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-52857 (URN)10.1016/j.jcrysgro.2009.10.011 (DOI)
    Available from: 2010-01-12 Created: 2010-01-12 Last updated: 2017-12-12
    2. High growth rate of 4H-SiC epilayers grown on on-axis substrates with different chlorinated precursors
    Open this publication in new window or tab >>High growth rate of 4H-SiC epilayers grown on on-axis substrates with different chlorinated precursors
    Show others...
    2010 (English)In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 12, 5334-5340 p.Article in journal (Refereed) Published
    Abstract [en]

    The epitaxial growth of 4H-SiC on on-axis substrates is a very important process to develop in order to accelerate the development and improve the performance of bipolar SiC based power devices, but until now, only relatively low growth rate processes have been demonstrated. The aim of this study is to demonstrate a high growth rate deposition process of high quality 4H-SiC epilayers on on-axis substrates, free of 3C-SiC inclusions. Previous studies showed that silicon-rich gas-phase conditions (prior to, and during the deposition process) and/or high Cl/Si ratios were vital in order to avoid 3C-SiC inclusions in the epitaxial layers when growing on on-axis substrates. This study combines the knowledge of surface pre-treatment with the chloride-based chemistry developed for off-axis growth. Two different precursor approaches were used, one adopting the standard precursors (silane and ethylene) with addition of hydrogen chloride (HCl), and the other based on the molecule methyltrichlorosilane (CH3SiCl3 or MTS). In this study we will show that using a MTS-based CVD process in combination with proper in situ silane etching and accurate optimisation of the other process parameters (temperature, C/Si and Cl/Si ratio) results in homoepitaxial growth of high purity and high quality 4H-SiC layers on on-axis Si-face substrates at a growth rate of 100 μm/h. Additionally, a higher efficiency of the MTS precursor chemistry was found and discussed.

    Place, publisher, year, edition, pages
    American Chemical Society, 2010
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60216 (URN)10.1021/cg101288u (DOI)000284675100045 ()
    Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12
    3. Improved morphology for epitaxial growth on 4° off-axis 4H-SiC substrates
    Open this publication in new window or tab >>Improved morphology for epitaxial growth on 4° off-axis 4H-SiC substrates
    Show others...
    2009 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 12, 3265-3272 p.Article in journal (Refereed) Published
    Abstract [en]

    A process optimization of the growth of SiC epilayers on 4° off-axis 4H-SiC substrates is reported. Process parameters such as growth temperature, C/Si-ratio and temperature ramp up conditions are optimized for the standard non-chlorinated growth in order to grow smooth epilayers without step-bunching and triangular defects. The growth of 6 μm thick n-type doped epitaxial layers on 75 mm diameter wafers is demonstrated as well as that of 20 μm thick layer. The optimized process was then transferred to a chloride-based process and a growth rate 28 μm/h was achieved without morphology degradation. A low growth temperature and a low C/Si ratio are the key parameters to reduce both the step-bunching and the formation of triangular defects.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-15251 (URN)10.1016/j.jcrysgro.2009.03.037 (DOI)
    Available from: 2008-10-29 Created: 2008-10-27 Last updated: 2017-12-14Bibliographically approved
    4. Growth of smooth 4H-SiC epilayers on 4° off-axis substrates with chloride-based CVD at very high growth rate
    Open this publication in new window or tab >>Growth of smooth 4H-SiC epilayers on 4° off-axis substrates with chloride-based CVD at very high growth rate
    Show others...
    2011 (English)In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 46, no 8, 1272-1275 p.Article in journal (Refereed) Published
    Abstract [en]

    4H-SiC epilayers grown on 4º off-axis substrates at high rates usually suffer from step-bunching (very high surface roughness) or of extended triangular defects, both detrimental for device performance.

    In this study we developed a novel in situ pre-growth surface preparation based on hydrogen chloride (HCl) addition at a temperature higher than that used for the growth. This pre-growth etching procedure minimizes the density of triangular defects which usually occur at low temperatures and simultaneously enables growth at a temperature low enough to avoid stepbunching. Thanks to this surface preparation step, chloride-based CVD could be used for rapid epitaxial growth of high quality layers. In this study, layers were grown at rates of 100 μm/h yielding defect free epitaxial layers with very smooth surface (RMS value of 8.9 Å on 100x100 μm2 area).

    Place, publisher, year, edition, pages
    Elsevier, 2011
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60217 (URN)10.1016/j.materresbull.2011.03.029 (DOI)
    Note
    The original title of this article was "Growth of step-bunch free 4H-SiC epilayers on 4º off-axis substrates using chloride-based CVD at very high growth rate". The status of this article has changed from "Manuscript" to "Article in journal".Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12Bibliographically approved
    5. Optimization of a Concentrated Chloride-Based CVD Process for 4H–SiC Epilayers
    Open this publication in new window or tab >>Optimization of a Concentrated Chloride-Based CVD Process for 4H–SiC Epilayers
    Show others...
    2010 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 10, H969-H979 p.Article in journal (Refereed) Published
    Abstract [en]

    Concentrated homoepitaxial growths of 4H–SiC was performed using a chloride-based chemical vapor deposition (CVD) process on different off-angle substrates (on-axis, 4 and 8° off-axis toward the [110] direction). A suitable combination of gas flow and process pressure is needed to produce the gas speed that yields an optimum cracking of the precursors and a uniform gas distribution for deposition over large areas. The use of low pressure and the addition of chlorinated precursors bring the added benefit of achieving higher growth rates. A systematic study of the gas speed's effect on the growth rate, uniformity, and morphology on the 4H–SiC epitaxial layers was performed. Growth rates in excess of 50  µm/h were achieved on 50 mm diameter wafers with excellent thickness uniformity (below 2% /mean without rotation of the substrate) and smooth morphology using only 1/10 of the typical gas carrier flow and process pressure demonstrating the feasibility of a concentrated chloride-based CVD process for 4H–SiC. Thermodynamic calculations showed that the improved thickness uniformity could be due to a more uniform gas phase composition of the silicon intermediates. The concentration of the SiCl2 intermediate increases by a factor of 8 at a reduced carrier flow, while all the other hydrogenated silicon intermediates decrease.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60218 (URN)10.1149/1.3473813 (DOI)
    Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12
    6. Chlorinated precursor study in low temperature CVD of 4H-SiC
    Open this publication in new window or tab >>Chlorinated precursor study in low temperature CVD of 4H-SiC
    Show others...
    2011 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 10, 3074-3080 p.Article in journal (Refereed) Published
    Abstract [en]

    Low temperature chemical vapour deposition of SiC has gained interest in the last years for being less demanding in terms of reaction chamber lifetime, but also for allowing higher p-type dopant incorporation. Chloride-based CVD at low temperatures has been studied using chloromethane with tetrachlorosilane or silane, respectively and with or without controlled HCl addition. In this study we explore the use of methyltrichlorosilane (MTS) at growth temperatures significantly lower than what is commonly used for homoepitaxial growth of SiC. MTS is a molecule containing all the needed precursor atoms; its effects are compared to the standard CVD chemistry, consisting of silane, ethylene, and HCl.

    Very different chemistries between the two precursor systems are proposed; in the case of MTS, C/Si ratios higher than 1 were required, however using the standard chemistry ratios lower than 1 were needed to obtain a defect-free epitaxial layer. We also demonstrate the need of using Cl/Si ratios as high as 15 to achieve a growth rate of 13 μm/h for 8° off-axis 4H-SiC epitaxial layers at 1300 °C. Limitations due to the low growth temperature are discussed in light of the experimental evidence on the growth mechanism as determined by the morphology degradation and the limited growth rate. Finally a comparison between the epilayers morphology obtained on 4H-SiC substrates with different off-cuts are presented, confirming the importance of lower C/Si ratios for 4° off-axis material and the inevitable growth of the cubic SiC polytype on on-axis substrates.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60219 (URN)10.1016/j.tsf.2010.12.119 (DOI)000289174300013 ()
    Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12
    7. Chloride-based CVD of 3C-SiC epitaxial layers on 6H(0001) SiC
    Open this publication in new window or tab >>Chloride-based CVD of 3C-SiC epitaxial layers on 6H(0001) SiC
    Show others...
    2010 (English)In: Physica Status Solidi (RRL) – Rapid Research Letters, ISSN 1862-6270, Vol. 4, no 11, 305-307 p.Article in journal (Refereed) Published
    Abstract [en]

    The growth of 3C‐SiC epitaxial layers on nominally on‐axis 6H‐SiC Si‐face substrates using the chloride‐based CVD process is demonstrated. A hot‐wall CVD reactor was used and HCl was added to the standard precursors (silane and ethylene). Several growth parameters were tested: temperature, in‐situ surface preparation, C/Si ratio, Cl/Si ratio, and nitrogen addition. Each parameter had a very important effect on the polytype formation. In the case of 3C‐SiC deposition the morphology and typology of defects could change significantly depending on the different combinations of growth conditions, including the addition of nitrogen. At a growth rate of 10 μm/h, a mirror‐like surface with a single domain decorated by some parallel stripes and few epitaxial defects were obtained. The near‐band gap luminescence of high quality 3C‐SiC layers was characterized by very sharp lines. Microscope and AFM analysis showed a very smooth surface. A background doping in the low 1015 cm−3 range was achieved.

    Place, publisher, year, edition, pages
    John Wiley and Sons, 2010
    Keyword
    Semiconductors; chemical vapour deposition; silicon carbide; epitaxy
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60220 (URN)10.1063/1.3518317 (DOI)000284206700003 ()
    Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2014-10-08
    8. Chloride-Based SiC Epitaxial Growth toward Low Temperature Bulk Growth
    Open this publication in new window or tab >>Chloride-Based SiC Epitaxial Growth toward Low Temperature Bulk Growth
    Show others...
    2010 (English)In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 8, 3743-3751 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study, chloride-based chemical vapor deposition (CVD) of SiC is used either to grow epitaxial layers at high growth rate and to facilitate homopolytypic growth on on-axis substrates or to grow bulk material at temperatures lower than 2000 °C. A vertical reactor configuration with an inlet of gas flow placed at the bottom of the reactor chamber and the exhaust at the top of it has been used. The chlorinated precursors have helped to eliminate or greatly reduce cluster formation, thereby allowing the deposition of thick SiC epilayers at growth rates exceeding 300 μm/h at 1700−1900 °C. Up to 1.5 mm thick homoepitaxial layers have been grown on up to 75 mm diameter 4H- or 6H-SiC wafers. Both on-axis and off-axis, Si-face and C-face polarities have been used. Our results show great promise for the realization of a high growth rate epitaxial process suitable for bulk growth at temperatures lower than those typically used. Such a process is interesting on account of the higher quality material and lower operating cost.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-60221 (URN)10.1021/cg1005743 (DOI)
    Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12
  • 17.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-Based SiC Epitaxial Growth toward Low Temperature Bulk Growth2010In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 8, 3743-3751 p.Article in journal (Refereed)
    Abstract [en]

    In this study, chloride-based chemical vapor deposition (CVD) of SiC is used either to grow epitaxial layers at high growth rate and to facilitate homopolytypic growth on on-axis substrates or to grow bulk material at temperatures lower than 2000 °C. A vertical reactor configuration with an inlet of gas flow placed at the bottom of the reactor chamber and the exhaust at the top of it has been used. The chlorinated precursors have helped to eliminate or greatly reduce cluster formation, thereby allowing the deposition of thick SiC epilayers at growth rates exceeding 300 μm/h at 1700−1900 °C. Up to 1.5 mm thick homoepitaxial layers have been grown on up to 75 mm diameter 4H- or 6H-SiC wafers. Both on-axis and off-axis, Si-face and C-face polarities have been used. Our results show great promise for the realization of a high growth rate epitaxial process suitable for bulk growth at temperatures lower than those typically used. Such a process is interesting on account of the higher quality material and lower operating cost.

  • 18.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-based CVD of 3C-SiC epitaxial layers on 6H(0001) SiC2010In: Physica Status Solidi (RRL) – Rapid Research Letters, ISSN 1862-6270, Vol. 4, no 11, 305-307 p.Article in journal (Refereed)
    Abstract [en]

    The growth of 3C‐SiC epitaxial layers on nominally on‐axis 6H‐SiC Si‐face substrates using the chloride‐based CVD process is demonstrated. A hot‐wall CVD reactor was used and HCl was added to the standard precursors (silane and ethylene). Several growth parameters were tested: temperature, in‐situ surface preparation, C/Si ratio, Cl/Si ratio, and nitrogen addition. Each parameter had a very important effect on the polytype formation. In the case of 3C‐SiC deposition the morphology and typology of defects could change significantly depending on the different combinations of growth conditions, including the addition of nitrogen. At a growth rate of 10 μm/h, a mirror‐like surface with a single domain decorated by some parallel stripes and few epitaxial defects were obtained. The near‐band gap luminescence of high quality 3C‐SiC layers was characterized by very sharp lines. Microscope and AFM analysis showed a very smooth surface. A background doping in the low 1015 cm−3 range was achieved.

  • 19.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-based CVD of 3C-SiC Epitaxial Layers on On-axis 6H (0001) SiC Substrates2010In: AIP Conference Proceedings, Vol. 1292, 2010, 7-10 p.Conference paper (Refereed)
  • 20.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chlorinated precursor study in low temperature CVD of 4H-SiC2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 10, 3074-3080 p.Article in journal (Refereed)
    Abstract [en]

    Low temperature chemical vapour deposition of SiC has gained interest in the last years for being less demanding in terms of reaction chamber lifetime, but also for allowing higher p-type dopant incorporation. Chloride-based CVD at low temperatures has been studied using chloromethane with tetrachlorosilane or silane, respectively and with or without controlled HCl addition. In this study we explore the use of methyltrichlorosilane (MTS) at growth temperatures significantly lower than what is commonly used for homoepitaxial growth of SiC. MTS is a molecule containing all the needed precursor atoms; its effects are compared to the standard CVD chemistry, consisting of silane, ethylene, and HCl.

    Very different chemistries between the two precursor systems are proposed; in the case of MTS, C/Si ratios higher than 1 were required, however using the standard chemistry ratios lower than 1 were needed to obtain a defect-free epitaxial layer. We also demonstrate the need of using Cl/Si ratios as high as 15 to achieve a growth rate of 13 μm/h for 8° off-axis 4H-SiC epitaxial layers at 1300 °C. Limitations due to the low growth temperature are discussed in light of the experimental evidence on the growth mechanism as determined by the morphology degradation and the limited growth rate. Finally a comparison between the epilayers morphology obtained on 4H-SiC substrates with different off-cuts are presented, confirming the importance of lower C/Si ratios for 4° off-axis material and the inevitable growth of the cubic SiC polytype on on-axis substrates.

  • 21.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Growth of smooth 4H-SiC epilayers on 4° off-axis substrates with chloride-based CVD at very high growth rate2011In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 46, no 8, 1272-1275 p.Article in journal (Refereed)
    Abstract [en]

    4H-SiC epilayers grown on 4º off-axis substrates at high rates usually suffer from step-bunching (very high surface roughness) or of extended triangular defects, both detrimental for device performance.

    In this study we developed a novel in situ pre-growth surface preparation based on hydrogen chloride (HCl) addition at a temperature higher than that used for the growth. This pre-growth etching procedure minimizes the density of triangular defects which usually occur at low temperatures and simultaneously enables growth at a temperature low enough to avoid stepbunching. Thanks to this surface preparation step, chloride-based CVD could be used for rapid epitaxial growth of high quality layers. In this study, layers were grown at rates of 100 μm/h yielding defect free epitaxial layers with very smooth surface (RMS value of 8.9 Å on 100x100 μm2 area).

  • 22.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    High growth rate of 4H-SiC epilayers grown on on-axis substrates with different chlorinated precursors2010In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 12, 5334-5340 p.Article in journal (Refereed)
    Abstract [en]

    The epitaxial growth of 4H-SiC on on-axis substrates is a very important process to develop in order to accelerate the development and improve the performance of bipolar SiC based power devices, but until now, only relatively low growth rate processes have been demonstrated. The aim of this study is to demonstrate a high growth rate deposition process of high quality 4H-SiC epilayers on on-axis substrates, free of 3C-SiC inclusions. Previous studies showed that silicon-rich gas-phase conditions (prior to, and during the deposition process) and/or high Cl/Si ratios were vital in order to avoid 3C-SiC inclusions in the epitaxial layers when growing on on-axis substrates. This study combines the knowledge of surface pre-treatment with the chloride-based chemistry developed for off-axis growth. Two different precursor approaches were used, one adopting the standard precursors (silane and ethylene) with addition of hydrogen chloride (HCl), and the other based on the molecule methyltrichlorosilane (CH3SiCl3 or MTS). In this study we will show that using a MTS-based CVD process in combination with proper in situ silane etching and accurate optimisation of the other process parameters (temperature, C/Si and Cl/Si ratio) results in homoepitaxial growth of high purity and high quality 4H-SiC layers on on-axis Si-face substrates at a growth rate of 100 μm/h. Additionally, a higher efficiency of the MTS precursor chemistry was found and discussed.

  • 23.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Optimization of a Concentrated Chloride-Based CVD Process for 4H–SiC Epilayers2010In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 10, H969-H979 p.Article in journal (Refereed)
    Abstract [en]

    Concentrated homoepitaxial growths of 4H–SiC was performed using a chloride-based chemical vapor deposition (CVD) process on different off-angle substrates (on-axis, 4 and 8° off-axis toward the [110] direction). A suitable combination of gas flow and process pressure is needed to produce the gas speed that yields an optimum cracking of the precursors and a uniform gas distribution for deposition over large areas. The use of low pressure and the addition of chlorinated precursors bring the added benefit of achieving higher growth rates. A systematic study of the gas speed's effect on the growth rate, uniformity, and morphology on the 4H–SiC epitaxial layers was performed. Growth rates in excess of 50  µm/h were achieved on 50 mm diameter wafers with excellent thickness uniformity (below 2% /mean without rotation of the substrate) and smooth morphology using only 1/10 of the typical gas carrier flow and process pressure demonstrating the feasibility of a concentrated chloride-based CVD process for 4H–SiC. Thermodynamic calculations showed that the improved thickness uniformity could be due to a more uniform gas phase composition of the silicon intermediates. The concentration of the SiCl2 intermediate increases by a factor of 8 at a reduced carrier flow, while all the other hydrogenated silicon intermediates decrease.

  • 24.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nishizawa, S.
    National Institute Adv Ind Science and Technology, Japan .
    Epitaxial growth of SiC with chlorinated precursors on different off-angle substrates2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 362, 170-173 p.Article in journal (Refereed)
    Abstract [en]

    This study focuses on the epitaxial growth of silicon carbide (SiC) epitaxial layers, adopting the chloride-based chemical-vapor-deposition (CVD) process, which allows to achieve ten times higher growth rate compared to the standard process based on the mixture of a silicon-containing gas and a hydrocarbon. In order to improve the material quality, substrates with different off-angles were used, since low off-angle substrates result in a reduction of killer defects for specific devices. Different growth mechanisms dominate for different substrate off-cut and an accurate set up of dedicated surface preparation procedures and tuning of growth parameters are needed. This study demonstrates that silicon-rich gas inputs are favorable for lower off-angle (nominally on-axis) substrates, while carbon-rich are beneficial for higher off-angles (usually 8 degrees off-axis for 4H-SiC). Methyltrichlorosilane (MTS) is shown to be the best precursor to achieve the presented results.

  • 25.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-based CVD at high growth rates on 3 vicinal off-angles SiC wafers2010Conference paper (Refereed)
    Abstract [en]

    Chloride-based growth on on-axis SiC substrates has been studied at higher temperature than typical CVD conditions. The use of chlorinated precursors allows to grow homo-polytypic layers and to achieve high growth rates for thick layers deposition. In this study a vertical reactor with the gas flow inlet at the bottom has been used to grow layers up to 1.5 mm thick. Thanks to the addition of hydrogen chloride (HCl) to the standard precursors mixture, growth rates up to 300 mu m/h have been achieved at a process temperature lower than 1900 degrees C. Very pure layers, micropipe free, and with a low background doping have been grown on 4H and 6H-SiC carbon and silicon-face, respectively, on-axis 3 diameter substrates. The results obtained indicates that this process has the potential to become a novel bulk growth technique at lower temperature than usual, which could give several advantages.

  • 26.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nishizawa, Shin-ichi
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Danielsson, Örjan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gas-Phase Modeling of Chlorine-Based Chemical Vapor Deposition of Silicon Carbide2012In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 12, no 4, 1977-1984 p.Article in journal (Refereed)
    Abstract [en]

    Kinetic calculations of the chemical phenomena occurring in the epitaxial growth of silicon carbide are performed in this study. The main process parameters analyzed are precursor types, growth temperature, Cl/Si ratio, and precursors concentration. The analysis of the gas-phase reactions resulted in a model which could explain most of the already reported experimental results, performed in horizontal hot-wall reactors. The effect of using different carbon or silicon precursors is discussed, by comparing the gas-phase composition and the resulting C/Si ratio inside the hot reaction chamber. Chlorinated molecules with three chlorine atoms seem to be the most efficient and resulting in a uniform C/Si ratio along the susceptor coordinate. Further complexity in the process derives from the use of low temperatures, which affects not only the gas-phase composition but also the risk of gas-phase nucleation. The Cl/Si ratio is demonstrated to be crucial not only for the prevention of silicon clusters but also for the uniformity of the gas-phase composition.

  • 27.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lin, Yuan-Chih
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska C.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-Based CVD at High Rates of 4H-SiC on On-Axis Si-Face Substrates2011In: Materials Science Forum Vols. 679-680 (2011) pp 59-62, Trans Tech Publications Inc., 2011, 59-62 p.Conference paper (Refereed)
    Abstract [en]

    The epitaxial growth at 100 µm/h on on-axis 4H-SiC substrates is demonstrated in this study. Chloride-based CVD, which has been shown to be a reliable process to grow SiC epitaxial layers at rates above 100 µm/h on off-cut substrates, was combined with silane in-situ etching. A proper tuning of C/Si and Cl/Si ratios and the combination of different chlorinated precursors resulted in the homoepitaxial growth of 4H-SiC on Si-face substrates at high rates. Methyltrichlorosilane, added with silane, ethylene and hydrogen chloride were employed as precursors to perform epitaxial growths resulting in very low background doping concentration and high quality material, which could be employed for power devices structure on basal-plane-dislocation-free epitaxial layers.

  • 28.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Canino, Andrea
    Consiglio Nazionale delle Ricerche IMM, Catania, Italy.
    La Via, Francesco
    Consiglio Nazionale delle Ricerche IMM, Catania, Italy.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-Based CVD of 4H-SiC at High Growth Rates on Substrates with Different Off-Angles2012In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, 113-116 p.Conference paper (Refereed)
    Abstract [en]

    A review of recently achieved results with the chloride-based CVD on 8 degrees and 4 degrees off-axis and nominally on-axis 4H-SiC wafers is done to clarify the epitaxial growth mechanisms on different off-angle substrates. The process conditions selected for each off-axis angle become even more difficult when running at growth rates of 100 mu m/h or more. A fine-tuning of process parameters, mainly temperature, C/Si ratio and in situ surface preparation is necessary for each Wangle. Some trends related to the surface properties and the effective C/Si ratio existing on the surface prior to and during the epitaxial growth can be observed.

  • 29.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Caracal Inc., 611 Eljer way, Ford City, PA, 16226, USA.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Homoepitaxial growth of 4H-SiC on on-axis Si-face substrates using chloride-based CVD2009Conference paper (Refereed)
    Abstract [en]

    The homoepitaxial chloride-based CVD growth is demonstrated on Si-face on-axis 4HSiC substrates. The use of chloride-based CVD has allowed growth of 100% 4H-SiC epitaxial layers with a growth rate of 20μm/h, thus about seven times higher than with standard precursors. It was also found that chlorine etches preferentially the 3C-SiC inclusions that tends to nucleate on Siface on-axis substrates. Therefore the Cl/Si ratio is a fundamental process parameter to optimize.

  • 30.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Caracal Inc., 611 Eljer way, Ford City, PA, 16226, USA.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Improved morphology for epitaxial growth on 4° off-axis 4H-SiC substrates2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 12, 3265-3272 p.Article in journal (Refereed)
    Abstract [en]

    A process optimization of the growth of SiC epilayers on 4° off-axis 4H-SiC substrates is reported. Process parameters such as growth temperature, C/Si-ratio and temperature ramp up conditions are optimized for the standard non-chlorinated growth in order to grow smooth epilayers without step-bunching and triangular defects. The growth of 6 μm thick n-type doped epitaxial layers on 75 mm diameter wafers is demonstrated as well as that of 20 μm thick layer. The optimized process was then transferred to a chloride-based process and a growth rate 28 μm/h was achieved without morphology degradation. A low growth temperature and a low C/Si ratio are the key parameters to reduce both the step-bunching and the formation of triangular defects.

  • 31.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Thick homoepitaxial layers grown on on-axis Si-face 6H- and 4H-SiC substrates with HCl addition2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 1, 24-32 p.Article in journal (Refereed)
    Abstract [en]

    The homoepitaxial growth of 6H- and 4H-SiC on on-axis substrates has been studied in order to demonstrate the growth of thick, mirror-like epitaxial layers without other polytype inclusions and basal plane dislocations. The study was done in a hot wall reactor using standard precursors silane and ethylene with hydrogen chloride (HCl) addition. The main important process parameters were studied, in particular deposition temperature, and precursor ratios such as C/Si, Cl/Si and Si/H2. The addition of chlorine in the precursor mixture was found to be the key parameter to grow layers at high rate with morphology and thickness similar to epilayers deposited on commonly used off-axis substrates. Two different process conditions were found allowing growth of low-doped (in the low 1014 cm−3 range) 100-μm-thick epitaxial layers at a growth rate of 25 μm/h, 8 times higher than what is achieved without HCl addition. A high concentration of SiCl2 in the gas phase obtained by high Cl/Si and Si/C ratios was fundamental to achieve these results.

  • 32.
    Leone, Stefano
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Pedersen, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Rao, S.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Growth of Thick 4H-SiC Epitaxial Layers on On-axis Si-Face Substrates with HCl Addition2009In: Materials Science Forum, Vols. 615-617, Trans Tech Publications , 2009, 93-96 p.Conference paper (Refereed)
    Abstract [en]

    Homoepitaxial growth of 4H-SiC on on-axis Si-face substrates is reported using hydrogen chloride together with silane and ethylene. In this study, the main process parameters, such as temperature, Cl/Si ratio, C/Si ratio, Si/H2 ratio and ramp up conditions, were studied in detail to understand their effects on the growth mechanisms. Two different optimal epitaxial growth conditions were found. Silicon rich conditions and a high Cl/Si ratio were the key parameters to grow thick homoepitaxial layers with a very low background doping concentration and a growth rate higher than 20 μm/h.

  • 33.
    Li, Xun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Andersson, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    CVD Heteroepitaxial Growth of 3C-SiC on 4H-SiC (0001) Substrates2012In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, 189-192 p.Conference paper (Refereed)
    Abstract [en]

    This study has been focused on 3C-SiC epitaxial growth on 4H-SiC (0001) on-axis substrates using the standard CVD chemistry. Several growth parameters were investigated, including growth temperature, in-situ etching process and C/Si ratio. High quality single domain 3C epilayers could be obtained around 1350 degrees C, with propane present during pre-growth etching and when the C/Si ratio was equal to 1. The best grown layer is 100% 3C-SiC and single domain. The net n-type background doping is around 2x10(16) cm(-3). The surface roughness of the layers from AFM analysis is in the 3 to 8 nm range on a 50x50 mu m(2) area.

  • 34.
    Pedersen, Henrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Very high growth rate of 4H-SiC epilayers using the chlorinated precursor methyltrichlorosilane (MTS)2007In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 307, no 2, 334-340 p.Article in journal (Refereed)
    Abstract [en]

    The chlorinated precursor methyltrichlorosilane (MTS), CH3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall chemical vapour deposition (CVD) reactor with growth rates higher than 100 μm/h. The addition of chlorinated species to the gas mixture prevents silicon nucleation in the gas phase, thus allowing higher input flows of the precursors resulting in much higher growth rate than that of standard silicon carbide (SiC) epitaxial growth using only silane, SiH4, and hydrocarbons as precursors. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate, morphology, and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor. The growth rate dropped for C/Si<1 but was constant for C/Si>1. Further, the growth rate decreased with lower Cl/Si ratio. This study shows that MTS is a promising precursor for homoepitaxial growth of SiC within the concept of chloride-based SiC growth.

  • 35.
    Pedersen, Henrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Caracal Inc..
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Very high growth rate of 4H-SiC using MTS as chloride-based precursor2009In: Materials Science Forum, Vol. 600-603, Trans Tech Publications , 2009, Vol. 600-603, 115-118 p.Conference paper (Refereed)
    Abstract [en]

    The chlorinated precursor methyltrichlorosilane (MTS), CH 3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall CVD reactor, with growth rates as high as 170 µm/h at 1600°C. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor up to about 100 µm/h. The growth rate dropped for C/Si less than 1 but was constant for C/Si greater than 1. Further, the growth rate decreased with lower Cl/Si ratio.

  • 36.
    Pedersen, Henrik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Leone, Stefano
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Beyer, Franziska
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Lundskog, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chloride-based SiC epitaxial growth2009In: Materials Science Forum Vols. 615-617, Trans Tech Publications , 2009, 89- p.Conference paper (Refereed)
    Abstract [en]

    Some aspects of the chloride-based CVD growth process have been investigated by using both the approach to add HCl to the standard precursors or/and by using the single molecule precursor methyltrichlorosilane (MTS). The efficiency of the process for different precursors, the growth rate stability and the effect that the Cl/Si-ratio has on the growth have been studied. MTS is showed to be the most efficient precursor; the growth can be hindered by to much chlorine in the gas mixture. The Cl/Si-ratio is also found to be a process parameter that affects the amount of incorporated nitrogen in the epilayers.

  • 37.
    Pedersen, Henrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Carlsson, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gällström, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Very high crystalline quality of thick 4H-SiC epilayers grown from methyltrichlorosilane (MTS)2008In: Physica status solidi (RRL) - Rapid Research Letters, ISSN 1862-6254, Vol. 2, no 4, 188-190 p.Article in journal (Refereed)
    Abstract [en]

    200 µm thick 4H-SiC epilayers have been grown by chloride-based chemical-vapor deposition using methyltrichlorosilane (MTS) as single precursor. The very high crystalline quality of the grown epilayer is demonstrated by high resolution X-Ray Diffraction rocking curve with a full-width-half-maximum value of only 9 arcsec. The high quality of the epilayer is further shown by low temperature photoluminescence showing strong free exciton and nitrogen bound exciton lines. The very high crystalline quality achieved for the thick epilayer grown in just two hours at 1600 °C suggests that MTS is a suitable precursor molecule for SiC bulk growth.

  • 38.
    Pedersen, Henrik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Leone, Stefano
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Darakchieva, Vanya
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Very high epitaxial growth rate of SiC using MTS as chloride-based precursor2007In: Surface and Coatings Technology, Volume 201, Issue 22-23 SPEC. ISS., Elsevier , 2007, 8931- p.Conference paper (Refereed)
    Abstract [en]

      

  • 39.
    Pedersen, Henrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lundskog, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Growth characteristics of chloride-based SiC epitaxial growth2008In: Physica status solidi (RRL) - Rapid Research Letters, ISSN 1862-6270, Vol. 2, no 6, 278-280 p.Article in journal (Refereed)
    Abstract [en]

    In this study some aspects of the chloride-based CVD growth process have been investigated by using both the approach to add HCl to the standard precursors and by using the single molecule precursor methyltrichlorosilane (MTS). The efficiency of the process for different precursors, the growth rate stability and the effect that the C/Si and Cl/Si ratios have on the growth are studied. It is found that MTS is the most efficient precursor and that the growth becomes carbon limited at C/Si < 1.

  • 40.
    Pedersen, Henrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nishizawa, Shin-ichi
    National Institute Adv Ind Science and Technology, Tsukuba.
    Koshka, Yaroslav
    Mississippi State University.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chloride-Based CVD Growth of Silicon Carbide for Electronic Applications2012In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 112, no 4, 2434-2453 p.Article, review/survey (Refereed)
    Abstract [en]

    n/a

  • 41.
    Son, Nguyen Tien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ivady, V.
    Hungarian Academy of Sciences, Budapest, Hungary.
    Gali, Adam
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Gällström, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Identification of Niobium in 4H-SiC by EPR and ab Initio Studies2012In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, 217-220 p.Conference paper (Refereed)
    Abstract [en]

    In unintentionally Nb-doped 4H-SiC grown by high-temperature chemical vapor deposition (HTCVD), an electron paramagnetic resonance (EPR) center with C-lh symmetry and an electron spin S=1/2 was observed. The spectrum shows a hyperfine structure consisting of ten equal-intensity hyperfine (hf) lines which is identified as due to the hf interaction between the electron spin and the nuclear spin of Nb-93. An additional hf structure due to the interaction with two equivalent Si neighbors was also observed. Ab initio supercell calculations of Nb in 4H-SiC suggest that Nb may form a complex with a C-vacancy (V-C) resulting in an asymmetric split-vacancy (ASV) defect, Nb-Si-V-C. Combining results from EPR and supercell calculations, we assign the observed Nb-related EPR center to the hexagonal-hexagonal configuration of the AVS defect in the neutral charge state, (Nb-Si-V-C)(0).

  • 42.
    Son Tien, Nguyen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Trinh, Xuan Thang
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gällström, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Szasz, Krisztian
    Hungarian Academic Science, Hungary .
    Ivady, Viktor
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Gali, Adam
    Hungarian Academic Science, Hungary Budapest University of Technology and Econ, Hungary .
    Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 8, 083711- p.Article in journal (Refereed)
    Abstract [en]

    High purity silicon carbide (SiC) materials are of interest from high-power high temperature applications across recent photo-voltaic cells to hosting solid state quantum bits, where the tight control of electrically, optically, and magnetically active point defects is pivotal in these areas. 4H- and 6H-SiC substrates are grown at high temperatures and the incorporation of transition metal impurities is common. In unintentionally Nb-doped 4H- and 6H-SiC substrates grown by high-temperature chemical vapor deposition, an electron paramagnetic resonance (EPR) spectrum with C-1h symmetry and a clear hyperfine (hf) structure consisting of ten equal intensity hf lines was observed. The hf structure can be identified as due to the interaction between the electron spin S - 1/2 and the nuclear spin of Nb-93. Additional hf structures due to the interaction with three Si neighbors were also detected. In 4H-SiC, a considerable spin density of similar to 37.4% was found on three Si neighbors, suggesting the defect to be a complex between Nb and a nearby carbon vacancy (V-C). Calculations of the Nb-93 and Si-29 hf constants of the neutral Nb on Si site, Nb-Si(0), and the Nb-vacancy defect, NbSiVC0, support previous reported results that Nb preferentially forms an asymmetric split-vacancy (ASV) defect. In both 4H- and 6H-SiC, only one Nb-related EPR spectrum has been observed, supporting the prediction from calculations that the hexagonal-hexagonal defect configuration of the ASV complex is more stable than others.

  • 43.
    Yazdanfar, Milan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Carrot defect control in chloride-based CVD through optimized ramp up conditions2012In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, 109-112 p.Conference paper (Refereed)
    Abstract [en]

    Epitaxial growth of 4H-SiC on 8 degrees off-axis substrates has been performed under different condition during the temperature ramp up in order to study the effect on the carrot defect. The study was done in a hot wall chemical vapor deposition reactor using the single molecule precursor methyltrichlorosilane (MTS). During the temperature ramp up, a small flow of HCl or C2H4 was added to the H-2 ambient to study different surface etching conditions. The best result was obtained when HCl was added from 1175 to 1520 degrees C during the ramp up to growth temperature (1575 degrees C).

1 - 43 of 43
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