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  • 51.
    Jokubavicius, Valdas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yazdi, G. Reza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Liljedahl, Rickard
    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.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lateral Enlargement Growth Mechanism of 3C-SiC on Off-Oriented 4H-SiC Substrates2014In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, no 12, p. 6514-6520Article in journal (Refereed)
    Abstract [en]

    We introduce a 3C-SiC growth concept on off-oriented 4H-SiC substrates using a sublimation epitaxial method. A growth model of 3C-SiC layer development via a controlled cubic polytype nucleation on in situ formed on-axis area followed by a lateral enlargement of 3C-SiC domains along the step-flow direction is outlined. Growth process stability and reproducibility of high crystalline quality material are demonstrated in a series of 3C-SiC samples with a thickness of about 1 mm. The average values of full width at half-maximum of ω rocking curves on these samples vary from 34 to 48 arcsec indicating high crystalline quality compared to values found in the literature. The low temperature photoluminescence measurements also confirm a high crystalline quality of 3C-SiC and indicate that the residual nitrogen concentration is about 1–2 × 1016 cm–3. Such a 3C-SiC growth concept may be applied to produce substrates for homoepitaxial 3C-SiC growth or seeds which could be explored in bulk growth of 3C-SiC.

  • 52.
    Jokubavicius, Valdas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yazdi, Gholam Reza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liljedahl, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Philipp, Schuh
    University of Erlangen, Erlangen, Germany.
    Wilhelm, Martin
    University of Erlangen, Erlangen, Germany.
    Wellmann, Peter
    University of Erlangen, Erlangen, Germany.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Single Domain 3C-SiC Growth on Off-Oriented 4H-SiC Substrates2015In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 15, no 6, p. 2940-2947Article in journal (Refereed)
    Abstract [en]

    We investigated the formation of structural defects in thick (∼1 mm) cubic silicon carbide (3C-SiC) layers grown on off-oriented 4H-SiC substrates via a lateral enlargement mechanism using different growth conditions. A two-step growth process based on this technique was developed, which provides a trade-off between the growth rate and the number of defects in the 3C-SiC layers. Moreover, we demonstrated that the two-step growth process combined with a geometrically controlled lateral enlargement mechanism allows the formation of a single 3C-SiC domain which enlarges and completely covers the substrate surface. High crystalline quality of the grown 3C-SiC layers is confirmed using high resolution X-ray diffraction and low temperature photoluminescence measurements.

  • 53.
    Kaiser, Michl
    et al.
    University of Erlangen-Nuremberg, Germany.
    Hupfer, Thomas
    University of Erlangen-Nuremberg, Germany.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Schimmel, Saskia
    University of Erlangen-Nuremberg, Germany.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Yiyu
    Technical University of Denmark, Lyngby.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Linnarsson, Margareta
    KTH Royal Institute of Technology, Kista, Sweden.
    Wellmann, Peter
    University of Erlangen-Nuremberg, Germany.
    Polycrystalline SiC as Source Material for the Growth of Fluorescent SiC Layers2013Conference paper (Refereed)
    Abstract [en]

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.

  • 54.
    Kaiser, Michl
    et al.
    University of Erlangen, Germany.
    Schimmel, Saskia
    University of Erlangen, Germany.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Linnarsson, Margareta
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Wellmann, Peter
    University of Erlangen, Germany.
    Nucleation and growth of polycrystalline SiC2014In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 56, no 1, p. 012001-Article in journal (Refereed)
    Abstract [en]

    The nucleation and bulk growth of polycrystalline SiC in a 2 inch PVT setup using isostatic and pyrolytic graphite as substrates was studied. Textured nucleation occurs under near-thermal equilibrium conditions at the initial growth stage with hexagonal platelet shaped crystallites of 4H, 6H and 15R polytypes. It is found that pyrolytic graphite results in enhanced texturing of the nucleating gas species. Reducing the pressure leads to growth of the crystallites until a closed polycrystalline SiC layer containing voids with a rough surface is developed. Bulk growth was conducted at 35 mbar Ar pressure at 2250°C in diffusion limited mass transport regime generating a convex shaped growth form of the solid-gas interface leading to lateral expansion of virtually [001] oriented crystallites. Growth at 2350°C led to the stabilization of 6H polytypic grains. The micropipe density in the bulk strongly depends on the substrate used.

  • 55.
    Kakanakova-Georgieva, Anelia
    et al.
    Sofia University.
    Paskova, T.
    Sofia University.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hallin, Christer
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Trifonova, E.P.
    Sofia University.
    Surtchev, M.
    Sofia University.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Structural properties of 6H-SiC epilayers grown by two different techniques1997In: Materials Science and Engineering B, ISSN 0921-5107, Vol. 46, no 1-3, p. 345-348Article in journal (Refereed)
    Abstract [en]

    In the present work we investigated the structural properties of 6H-SiC homoepitaxial layers utilizing microhardness and X-ray characterization techniques. The growth was performed by chemical vapour deposition (CVD) and liquid phase epitaxy (LPE) under various growth conditions. The depth Knoop hardness profiles represent decreasing curves due to the indentation size effect. With load increasing the curves saturate reaching microhardness values comparable with the known Vickers ones. At about 0.4 μm beneath the layer surfaces the curves show small plateaus which may be attributed to structural inhomogeneity. This is suggested by X-ray diffraction spectra taken from the same samples, which contain additional peaks besides the typical ones for 6H-SiC.

  • 56.
    Kakanakova-Georgieva, Anelia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Gueorguiev, G.K.
    Departamento De Fisica Da Universidade, 3004-516 Coimbra, Portugal.
    Linnarsson, M.K.
    Solid State Electronics, Royal Institute of Technology, P.O. Box E229, S-164 40 Kista, Sweden.
    Syväjärvi, Mikael
    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.
    Kinetics of residual doping in 4H-SiC epitaxial layers grown in vacuum2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 240, no 3-4, p. 501-507Article in journal (Refereed)
    Abstract [en]

    Investigation on residual Al, B, and N co-doping of 4H-SiC epitaxial layers is reported. The layers were produced by sublimation epitaxy in Ta growth cell environment at different growth temperatures and characterized by secondary ion mass spectrometry. The vapor interaction with Ta was considered through calculations of cohesive energies of several Si-, Al-, B-, and N-containing vapor molecules and also of diatomic Ta-X molecules. An analysis of kinetic mechanisms responsible for impurity incorporation is performed. Among residuals, B exhibits a stronger incorporation dependence on temperature and growth at lower temperatures can favor B decrease in the layers. Under the growth conditions in this study (Ta environment and presence of attendant Al and N), B incorporation is assisted by Si2C vapor molecule. Boron tends to occupy carbon sites at higher temperatures, i.e. higher growth rates. © 2002 Elsevier Science B.V. All rights reserved.

  • 57.
    Kakanakova-Georgieva, Anelia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, Rositsa
    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.
    Linnarsson, M.K.
    Royal Institute of Technology, PO Box E229, S-16440 Kista, Sweden.
    Syväjärvi, Mikael
    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.
    Cathodoluminescence identification of donor-acceptor related emissions in as-grown 4H-SiC layers2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 5, p. 2890-2895Article in journal (Refereed)
    Abstract [en]

    A comparative analysis of cathodoluminescence spectra in 4H-SiC layers with different N, Al, and B content is reported. The layers were produced by sublimation epitaxy and residual impurity concentrations were determined by secondary ion mass spectrometry. Epilayers doped with B in a wide concentration range, 5×1015-3×1018cm-3, were achieved. Evidence of N, Al, and B related emissions by cathodoluminescence experiments is presented. Differences in the luminescence emitted by the layers are established that are attributed to different B content and impurity cooperation. The characteristics of broad green emission, originating from B-related centers, at 4.6 K, 300 K, as well as in high temperature annealed layers are discussed. The experimental results suggest that boron is involved in more than one deep acceptor center. © 2002 American Institute of Physics.

  • 58.
    Kakanakova-Georgieva, Anelia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    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.
    Behavior of background impurities in thick 4H-SiC epitaxial layers2001In: Appl. Surf. Sci., Vol. 184, 2001, Vol. 184, no 1-4, p. 242-246Conference paper (Refereed)
    Abstract [en]

    Behavior of background impurities in 4H-SiC layers is studied in terms of several growth process parameters. The layers were produced by sublimation epitaxy in Ta and Hf, as well as in graphite growth cell environment. Cathodoluminescence imaging and spectroscopy of cleaved samples demonstrate the impurity - thickness uniformity along thick (40-260 µm) layers. The effect of the Ta and Hf environment on the levels of residual impurities is considered through calculations of cohesive energies of Ta-X and Hf-X diatomic molecules and comparing them with those obtained for N-, Al- and B-containing vapor molecules. © 2001 Elsevier Science B.V. All rights reserved.

  • 59.
    Kakanakova-Georgieva, Anelia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Zhang, J
    Storasta, Liutauras
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    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.
    Characteristics of boron in 4H-SiC layers produced by high-temperature techniques2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 259-262Conference paper (Refereed)
    Abstract [en]

    Characteristics of boron in as-grown 4H-SiC layers produced by fast epitaxy, i.e. sublimation and vertical hot-wall CVD, were studied by electrical and optical measurements. The boron-related contribution to the net acceptor concentration in the layers (as determined by CV on p-type residual doped sublimation epitaxy layers), the presence of deep boron centers (as indicated by DLTS) and boron-related "green" emission at similar to 505 nm (as observed by CL) are detected for various growth temperatures and C/Si ratios. The results are discussed in relation with the C vacancies in the lattice that may be affected by growth rate and input C/Si ratio in the CVD process.

  • 60. Kalabukhova, E.N.
    et al.
    Lukin, S.N.
    Savchenko, D.V.
    Mitchel, W.C.
    Greulich-Weber, S.
    Gerstmann, U.
    Pöppl, A.
    Hoentsch, J.
    Rauls, E.
    Rozentzveig, Y.
    Mokhov, E.N.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    EPR, ESE and Pulsed ENDOR Study of Nitrogen Related Centers in 4H-SiC Wafers Grown by Different Technologies2007In: ECSCRM 2006,2006, Material Science Forum, vol. 556-557: Trans Tech Publications , 2007, p. 355-Conference paper (Refereed)
  • 61.
    Kamiyama, Satoshi
    et al.
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku,.
    Iwaya, Motoaki
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku,.
    Takeuchi, Tetsuya
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku,.
    Akasaki, Isamu
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku,.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Fluorescent SiC and its application to white light-emitting diodes2011In: Journal of semiconductors, ISSN 1674-4926, Vol. 32, no 1, p. 013004-1-013004-3Article in journal (Refereed)
    Abstract [en]

    Fluorescent-SiC (f-SiC), which contains donor and acceptor impurities with optimum concentrations, has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair (DAP) recombination. This material can be used as a substrate for a near UV light-emitting diode (LED) stack, and leads to monolithic white LED device with suitable spectral property for general lighting applications. In this paper, we describe basic technologies of the white LED, such as optical properties of f-SiC substrate, and epitaxial growth of NUV stack on the f-SiC substrate.

  • 62.
    Kamiyama, Satoshi
    et al.
    Meijo University, Japan .
    Iwaya, Motoaki
    Meijo University, Japan .
    Takeuchi, Tetsuya
    Meijo University, Japan .
    Akasaki, Isamu
    Meijo University, Japan .
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    White light-emitting diode based on fluorescent SiC2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 522, p. 23-25Article in journal (Refereed)
    Abstract [en]

    A monolithic white light-emitting diode (LED,) comprising a combination of a fluorescent-SiC (f-SiC) substrate and a nitride-based near-UV LED stack, is proposed. On the basis of the recombination of donor and acceptor pairs, the f-SiC substrate works as a phosphor for visible light emission. By employing the Fast Sublimation Growth Process method, the high-quality f-SiC substrate doped with N and B exhibited a nonradiative carrier lifetime of 55 mu s and an internal quantum efficiency (IQE) of 40%. With increasing donor and acceptor doping concentrations, a high IQE was estimated even at a high excitation level.

  • 63.
    Karlsson, Mikael
    et al.
    Department of Sensor System, Acreo Swedish ICT AB, Box 1070, SE-16440 Kista, Sweden; Department of Materials and Nano Physics, KTH-Royal Institute of Technology, Kista, Sweden .
    Wang, Qin
    Department of Sensor System, Acreo Swedish ICT AB, Box 1070, SE-16440 Kista, Sweden.
    Zhao, Yichen
    Department of Materials and Nano Physics, KTH-Royal Institute of Technology, Kista, Sweden.
    Zhao, Wei
    Department of Sensor System, Acreo Swedish ICT AB, Box 1070, SE-16440 Kista, Sweden; Department of Materials and Nano Physics, KTH-Royal Institute of Technology, Kista, Sweden.
    Toprak, Muhammet S.
    Department of Materials and Nano Physics, KTH-Royal Institute of Technology, Kista, Sweden.
    Iakimov, Tihomir
    Graphensic AB, Mjärdevi Science Park, Teknikringen 1F, SE-58330 Linköping, Sweden.
    Ali, Amer
    Graphensic AB, Mjärdevi Science Park, Teknikringen 1F, SE-58330 Linköping, Sweden.
    Yakimova, Rositsa
    Graphensic AB, Mjärdevi Science Park, Teknikringen 1F, SE-58330 Linköping, Sweden.
    Syväjärvi, Mikael
    Graphensic AB, Mjärdevi Science Park, Teknikringen 1F, SE-58330 Linköping, Sweden.
    Ivanov, Ivan G.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Wafer-scale epitaxial graphene on SiC for sensing applications2015In: Micro+Nano Materials, Devices, and Systems / [ed] Benjamin J. Eggleton, Stefano Palomba, SPIE - International Society for Optical Engineering, 2015, Vol. 9668, p. 96685T-1-96685T-7Conference paper (Refereed)
    Abstract [en]

    The epitaxial graphene-on-silicon carbide (SiC-G) has advantages of high quality and large area coverage owing to a natural interface between graphene and SiC substrate with dimension up to 100 mm. It enables cost effective and reliable solutions for bridging the graphene-based sensors/devices from lab to industrial applications and commercialization. In this work, the structural, optical and electrical properties of wafer-scale graphene grown on 2’’ 4H semi-insulating (SI) SiC utilizing sublimation process were systemically investigated with focus on evaluation of the graphene’s uniformity across the wafer. As proof of concept, two types of glucose sensors based on SiC-G/Nafion/Glucose-oxidase (GOx) and SiC-G/Nafion/Chitosan/GOx were fabricated and their electrochemical properties were characterized by cyclic voltammetry (CV) measurements. In addition, a few similar glucose sensors based on graphene by chemical synthesis using modified Hummer’s method were also fabricated for comparison. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  • 64. Kasamakova-Kolaklieva, L
    et al.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kakanakov, R
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    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.
    Characteristics of Ni Schottky contacts on compensated 4H-SiC layers2003In: Materials Science Forum, Vols. 433-436, Trans Tech Publications , 2003, Vol. 433-4, p. 709-712Conference paper (Refereed)
    Abstract [en]

    The electrical properties of Ni Schottky contacts to compensated 4H-SiC layers have been characterized by means of IN and C-V measurements and the key parameters have been determined. The measured barrier heights were between 0.90 eV and 2.90 eV depending on the conductivity type and the donor/acceptor concentration as well as the measurement techniques used. Inhomogeneties in IN characteristics of some rectifiers at lower forward-bias voltages have been observed. This may suggest enhanced trapping mechanism due to the nonuniform boron compensation of the epilayers.

  • 65.
    Kassamakova, L
    et al.
    Bulgarian Acad Sci, Inst Appl Phys, BG-4000 Plovdiv, Bulgaria Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Kakanakov, R
    Bulgarian Acad Sci, Inst Appl Phys, BG-4000 Plovdiv, Bulgaria Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Wilzén, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Effect of temperature treatment on Au/Pd Schottky contacts to 4H-SiC2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 929-932Conference paper (Refereed)
    Abstract [en]

    Au/Pd/SiC Schottky baffler contacts have been formed on n-type 4H-SiC grown by sublimation epitaxy. The effect of annealing temperature on the electrical properties of these contacts was studied using IN and C-V measurements. The barrier height was found to increase slightly from 1.14 eV for as-deposited contacts to 1.2 eV after annealing at 500 degreesC, while the more pronounced effect was observed with decrease of the ideality factor, Auger analysis was used to study the metallurgy of the annealed contacts. Strong diffusion between Au and Pd was established after 500 degreesC anneal, while the Pd/SiC interface remained almost steep, The electrical properties of annealed contacts have been study during the thermal treatment at temperatures up to 350 degreesC and prolonged ageing at 300 degreesC and 400 degreesC in nitrogen.

  • 66. Khranovskyy, V
    et al.
    Tsiaoussis, I
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Larsson, Arvid
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Size tuning of uniformly oriented ZnO nanostructures2008In: Nanotech 2008,2008, 2008Conference paper (Refereed)
  • 67.
    Kwasnicki, Pawel
    et al.
    CNRS, L2C UMR 5221, F-34095, Montpellier, France.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Peyre, H.
    Université Montpellier 2, L2C UMR 5221, F-34095, Montpellier, France .
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Camasse, J.
    CNRS, L2C UMR 5221, F-34095, Montpellier, France .
    Juillaguet, S.
    Université Montpellier 2, L2C UMR 5221, F-34095, Montpellier, France.
    Optical investigation of 3C-SiC hetero-epitaxial layers grown by sublimation epitaxy under gas atmosphere2014In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 778-780, p. 243-246Article in journal (Refereed)
    Abstract [en]

    We investigated three 3C-SiC samples grown on 6H SiC substrate by sublimation epitaxy under gas atmosphere. We focus on the low temperature photoluminescence and Raman measurements to show that compare to a growth process under vacuum atmosphere, the gas atmosphere favor the incorporation of impurities at already existing and/or newly created defect sites.

  • 68.
    Lebedev, Alexander
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Davydov, DV
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia Linkoping Univ, S-58183 Linkoping, Sweden.
    Savkina, NS
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia Linkoping Univ, S-58183 Linkoping, Sweden.
    Tregubova, AS
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia Linkoping Univ, S-58183 Linkoping, Sweden.
    Shcheglov, MP
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia Linkoping Univ, S-58183 Linkoping, Sweden.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Structural defects and deep-level centers in 4H-SiC epilayers grown by sublimational epitaxy in vacuum2000In: Semiconductors (Woodbury, N.Y.), ISSN 1063-7826, E-ISSN 1090-6479, Vol. 34, no 10, p. 1133-1136Article in journal (Refereed)
    Abstract [en]

    The parameters of deep-level centers in lightly doped 4H-SiC epilayers grown by sublimational epitaxy and CVD were investigated. Two deep-level centers with activation energies E-c - 0.18 eV and E-c - 0.65 eV (Z1 center) were observed and tentatively identified with structural defects of the SiC crystal lattice. The Z1 center concentration is shown to fall with decreasing uncompensated donor concentration N-d - N-a in the layers. For the same N-d - N-a, the Z1 center concentration is lower in layers with a higher dislocation density. (C) 2000 MAIK "Nauka/Interperiodica".

  • 69.
    Lebedev, Alexander
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Zelenin, V.V.
    Abramov, P.L.
    Bogdanova, E.V.
    Lebedev, S.P.
    Nelson, D.K.
    Razbirin, B.S.
    Scheglov, M.P.
    Tregubova, A.S.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Growth and Study of Thick 3C-SiC Epitaxial Layers Produced by Epitaxy on 6H-SiC Substrates2007In: ECSCRM 2006,2006, Materials Science Forum, vol. 556.557: Trans Tech Publications , 2007, p. 175-Conference paper (Refereed)
  • 70.
    Lebedev, Alexander
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Zelenin, V.V.
    Abramov, P.L.
    Bogdanova, E.V.
    Lebedev, S.P.
    Nel¿son, D.K.
    Razbirin, B.S.
    Shcheglov, M.P.
    Tregubova, A.S.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    A study of thick 3C-SiC epitaxial layers grown on 6H-SiC substrates by sublimation epitaxy in vacuum2007In: Semiconductors (Woodbury, N.Y.), ISSN 1063-7826, E-ISSN 1090-6479, Vol. 41, no 3, p. 263-265Article in journal (Refereed)
    Abstract [en]

    3C-SiC epitaxial layers with a thickness of up to 100 μm were grown on 6H-SiC hexagonal substrates by sublimation epitaxy in vacuum. The n-type epitaxial layers with the area in the range 0.3-0.5 cm2 and uncompensated donor concentration N d - N a ∼ (10 17-1018) cm-3 were produced at maximum growth rates of up to 200 μm/h. An X-ray analysis demonstrated that the epitaxial layers are composed of the 3C-SiC polytype, without inclusions of other polytypes. The photoluminescence (PL) spectrum of the layers was found to be dominated by the donor-acceptor (Al-N) recombination band peaked at hv ≈ 2.12 eV. The PL spectrum measured at 6 K was analyzed in detail. It is concluded that the epitaxial layers obtained can serve as substrates for 3C-SiC-based electronic devices. © Nauka/Interperiodica 2007.

  • 71.
    Linnarsson, Margareta
    et al.
    KTH Royal Institute of Technology, Kista, Sweden.
    Kaiser, Michl
    University of Erlangen-Nuremberg, Germany.
    Liljedahl, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Yiyu
    Technical University of Denmark, Lyngby.
    Wellmann, Peter
    University of Erlangen-Nuremberg, Germany.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lateral Boron Distribution in Polycrystalline SiC Source Materials2013Conference paper (Refereed)
    Abstract [en]

    Polycrystalline SiC containing boron and nitrogen are used in growth of fluorescent SiC for white LEDs. Two types of doped polycrystalline SiC have been studied in detail with secondary ion mass spectrometry: sintered SiC and poly-SiC prepared by sublimation in a physical vapor transport setup. The materials are co-doped materials with nitrogen and boron to a concentration of 1x1018 cm-3 and 1x1019 cm-3, respectively. Depth profiles as well as ion images have been recorded. According to ocular inspection, the analyzed poly-SiC consists mainly of 4H-SiC and 6H-SiC grains. In these grains, the boron concentration is higher and the nitrogen concentration is lower in the 6H-SiC compared to the 4H-SiC polytype. No inter-diffusion between grains is observed.

  • 72.
    Lu, Wei Fang
    et al.
    Technical University of Denmark.
    Ou, Yiyu
    Technical University of Denmark.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Fadi, lAhmed
    Technical University of Denmark.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Buschmann, Volker
    PicoQuant GmbH, Rudower Chaussee 29, 12489 Berlin, Germany.
    Rüttinger, Steffen
    PicoQuant GmbH, Rudower Chaussee 29, 12489 Berlin, Germany.
    Petersen, Paul Michael
    Technical University of Denmark.
    Ou, Haiyan
    Technical University of Denmark.
    Photoluminescence enhancement in nano-textured fluorescent SiC passivated by atomic layer deposited Al2O3 films2016In: Silicon Carbide and Related Materials 2015, 2016, Vol. 858, p. 493-496Conference paper (Refereed)
    Abstract [en]

    The influence of thickness of atomic layer deposited Al2O3 films on nanotextured fluorescent 6H-SiC passivation is investigated. The passivation effect on the light emission has been characterized by photoluminescence and time-resolved photoluminescence at room temperature. The results show that 20nm thickness of Al2O3 layer is favorable to observe a large photoluminescence enhancement (25.9%) and long carrier lifetime (0.86ms). This is a strong indication for an interface hydrogenation that takes place during post-thermal annealing. These result show that an Al2O3 layer could serve as passivation in fluorescent SiC based white LEDs applications.

  • 73.
    Lu, Weifang
    et al.
    Technical University of Denmark, Denmark.
    Ou, Yiyu
    Technical University of Denmark, Denmark.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Fadil, Ahmed
    Technical University of Denmark, Denmark.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Michael Petersen, Paul
    Technical University of Denmark, Denmark.
    Ou, Haiyan
    Technical University of Denmark, Denmark.
    Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO22016In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 91, no 7, p. 074001-Article in journal (Refereed)
    Abstract [en]

    Nano-textured surfaces have played a key role in optoelectronic materials to enhance the light extraction efficiency. In this work, morphology and optical properties of nano-textured SiC covered with atomic layer deposited (ALD) TiO2 were investigated. In order to obtain a high quality surface for TiO2 deposition, a three-step cleaning procedure was introduced after RIE etching. The morphology of anatase TiO2 indicates that the nano-textured substrate has a much higher surface nucleated grain density than a flat substrate at the beginning of the deposition process. The corresponding reflectance increases with TiO2 thickness due to increased surface diffuse reflection. The passivation effect of ALD TiO2 thin film on the nano-textured fluorescent 6H-SiC sample was also investigated and a PL intensity improvement of 8.05% was obtained due to the surface passivation.

  • 74.
    Ma, Quanbao
    et al.
    University of Oslo.
    Carvalho, Patricia
    SINTEF.
    Galeckas, Augustinas
    University of Oslo.
    Alexander, Azarov
    University of Oslo.
    Hovden, Sigurd
    SINTEF.
    Thøgersen, Annett
    SINTEF.
    Wright, Daniel N.
    SINTEF ICT.
    Diplas, Spyros
    SINTEF.
    Løvvik, Ole M.
    SINTEF.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Svensson, Bengt G.
    University of Oslo.
    Characterization of B-Implanted 3C-SiC for Intermediate Band Solar Cells2017In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 897, p. 299-302Article in journal (Refereed)
    Abstract [en]

    Sublimation-grown 3C-SiC crystals were implanted with B ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 1.3×1017 atoms/cm2 in order to form intermediate band (IB) in 3C-SiC. The samples were then annealed at 1400 °C for 60 min. An anomalous area in the center was observed in the PL emission pattern. The SIMS analysis indicated that the B concentration was the same both within and outside the anomalous area. The buried boron box-like concentration profile can reach ~3×1021 cm-3 in the plateau region. In the anomalous area a broad emission band (possible IB) emerges at around ~1.7-1.8 eV, which may be associated with B-precipitates having a sufficiently high density.

  • 75.
    Ma, Quanbao
    et al.
    University of Oslo, Norway.
    Galeckas, Augustinas
    University of Oslo, Norway.
    Alexander, Azarov
    University of Oslo, Norway.
    Thøgersen, Annett
    SINTEF Materials and Chemistry, Norway.
    Carvalho, Patricia
    SINTEF Materials and Chemistry, Norway.
    Wright, Daniel N.
    SINTEF ICT, Norway.
    Diplas, Spyros
    SINTEF Materials and Chemistry, Norway.
    Løvvik, Ole M.
    SINTEF Materials and Chemistry, Norway.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Svensson, Bengt G.
    University of Oslo, Norway.
    Boron-implanted 3C-SiC for intermediate band solar cells2016In: Silicon Carbide and Related Materials 2015, 2016, Vol. 858, p. 291-294Conference paper (Refereed)
    Abstract [en]

    Sublimation-grown 3C-SiC crystals were implanted with 2 atomic percent of boron ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 8.5×1016 atoms/cm2. The samples were then annealed at 1400, 1500 and 1600 °C for 1h at each temperature. The buried boron box-like concentration profile can reach ~2×1021 cm-3 in the plateau region. The optical activity of the incorporated boron atoms was deduced from the evolution in absorption and emission spectra, indicating possible pathway for achieving an intermediate band behavior in boron doped 3C-SiC at sufficiently high dopant concentrations.                    

  • 76.
    Manolis, G
    et al.
    Institute of Applied Research, Vilnius University, Lithuania .
    Gulbinas, K
    Institute of Applied Research, Vilnius University, Lithuania.
    Grivickas, V.
    Institute of Applied Research, Vilnius University, Lithuania.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Linnarsson, Margareta
    Royal Institute of Technology, Kista, Sweden .
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Temperature Dependencies of Free-Carrier-Absorption Lifetime in Fluorescent 6H-SiC Layers2014In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 56, no 1, p. 012006-Article in journal (Refereed)
    Abstract [en]

    The nonradiative decay of majority electrons has been studied over a wide temperature range from 80 K to 600 K using the time-resolved free-carrier-absorption (FCA) technique. At high injection level of the highly-luminescent N-B codoped 6H-SiC epilayer, we revealed three main relaxation components of injected free electrons over ps-to-ms time ranges. By means of temperature dependency, two components can be ascribed to thermal activation of holes from a shallow (200 meV) and a deep (500 meV) acceptor. The third one, which has a hundred us-time scale, we attribute to minority hole recombination from the valance band into the electron trap (53 meV). This recombination channel seems to compete with the deep-acceptor (Boron) to-donor (Nitrogen) pair visible emission at and below 300 K.

  • 77.
    Murugesan, Murali
    et al.
    Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Gothenburg, Sweden.
    Zanden, Carl
    Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Gothenburg, Sweden.
    Luo, Xin
    Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Gothenburg, Sweden; School of Mechatronics and Mechanical Engineering, Key Laboratory of New Displays and System Integration, Shanghai University, China .
    Ye, Lilei
    SHT Smart High-Tech AB, Gothenburg, Sweden.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Liu, Johan
    Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Gothenburg, Sweden; School of Mechatronics and Mechanical Engineering, Key Laboratory of New Displays and System Integration, Shanghai University, China .
    A carbon fiber solder matrix composite for thermalmanagement of microelectronic devices2014In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 2, no 35, p. 7184-7187Article in journal (Refereed)
    Abstract [en]

    A carbon fiber based tin-silver-copper alloy matrix composite (CF-TIM) was developed via electrospinning of a mesophase pitch with polyimide and carbonization at 1000 °C, followed by sputter coating with titanium and gold, and alloy infiltration. The carbonized fibers, in film form, showed a thermal conductivity of ∼4 W m-1 K-1 and the CF-TIM showed an anisotropic thermal conductivity of 41 ± 2 W m-1 K-1 in-plane and 20 ± 3 W m-1 K-1 through-plane. The thermal contact resistance of the CF-TIM was estimated to be below 1 K mm2 W-1. The CF-TIM showed no reduction in effective through-plane thermal conductivity after 1000 temperature cycles, which indicates the potential use of CF-TIM in thermal management applications.

  • 78.
    Nakagomi, S
    et al.
    Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Shinobu, H
    Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Unéus, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ekedahl, Lars-Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    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, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Influence of epitaxial layer on SiC Schottky diode gas sensors operated under high-temperature conditions2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 1423-1426Conference paper (Refereed)
    Abstract [en]

    Schottky diode gas sensors were fabricated on top of the epitaxial layer grown by three different methods, purchased from Cree Research Inc., by hot wall CVD, or by sublimation at a high growth rate. The epitaxial layers have different thickness and doping. The current-voltage characteristics of the gas sensors were compared in different gas ambient during operation in the high temperature region. The temperature dependence of the series resistance of the diodes revealed two types of carrier scattering mechanisms, impurity scattering for the sublimation epitaxial layer at 300-400degreesC and at 400-600degreesC, lattice scattering for all diodes. The ideality factor of the diode fabricated on the Cree substrate is higher than others. The higher ideality factor gives rise to a larger forward voltage change for a change in gas ambient. The amount of change in barrier height caused by a change in the ambient gas is almost the same for the three types of diodes. The value of the barrier height of the diode grown by the sublimation method is lower than for the others, which gives a higher reverse saturation current at temperatures above 400degreesC. The largest saturation current also shows the largest current change when switching between different gas atmospheres.

  • 79.
    Neimontas, K.
    et al.
    Vilnius University.
    Jarasiunas, K.
    Vilnius University.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ferro, G.
    UCB Lyon I.
    Characterization of electronic properties of different SiC polytypes by all-optical means2009In: Materials Science Forum, Vols. 600-603, 2009, Vol. 600-603, p. 509-512Conference paper (Refereed)
    Abstract [en]

    We applied a picosecond transient grating technique for studies of nonequilibrium carrier dynamics in differently grown or doped SiC polytypes. Optical carrier injection in 4H-SiC at two different wavelengths (266 and 355 nm) allowed us to vary the depth of the photoexcited region and determine photoelectric parameters of high density (from ~1016 to ~1019 cm-3) carrier plasma in the temperature range 10-300 K. A strong decrease of carrier lifetime with increasing nonequlibrium carrier density was found in 4H-SiC samples at 300 K and fitted by bimolecular recombination with coefficient B = 3 � 10-11 cm3 s-1. In 3C-SiC epilayers, the opposite tendency was observed over a wide temperature range and attributed to recharging of defect states.

  • 80.
    Ou, Haiyan
    et al.
    Technical University of Denmark, Lyngby, Denmark .
    Ou, Yiyu
    Technical University of Denmark, Lyngby, Denmark .
    Argyraki, Aikaterini
    Technical University of Denmark, Lyngby, Denmark .
    Schimmel, Saskia
    University of Erlangen-Nuremberg, Erlangen, Germany .
    Kaiser, Michl
    University of Erlangen-Nuremberg, Erlangen, Germany .
    Wellmann, Peter
    University of Erlangen-Nuremberg, Erlangen, Germany .
    Linnarsson, Margareta
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Liljedahl, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Advances in wide bandgap SiC for optoelectronics2014In: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 87, p. 58-Article in journal (Refereed)
    Abstract [en]

    Silicon carbide (SiC) has played a key role in power electronics thanks to its unique physical properties like wide bandgap, high breakdown field, etc. During the past decade, SiC is also becoming more and more active in optoelectronics thanks to the progress in materials growth and nanofabrication. This paper will review the advances in fluorescent SiC for white light-emitting diodes, covering the poly-crystalline doped SiC source material growth, single crystalline epitaxy growth of fluorescent SiC, and nanofabrication of SiC to enhance the extraction efficiency for fluorescent SiC based white LEDs.

  • 81.
    Ou, Yiyu
    et al.
    Technical University of Denmark, Lyngby, Denmark.
    Aijaz, Imran
    Technical University of Denmark, Lyngby, Denmark.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Technical University of Denmark, Lyngby, Denmark.
    Broadband antireflection silicon carbide surface by self-assembled nanopatterned reactive-ion etching2013In: OPTICAL MATERIALS EXPRESS, ISSN 2159-3930, Vol. 3, no 1, p. 86-94Article in journal (Refereed)
    Abstract [en]

    An approach of fabricating pseudoperiodic antireflective subwavelength structures on silicon carbide by using self-assembled Au nanopatterns as etching mask is demonstrated. The nanopatterning process is more time-efficiency than the e-beam lithography or nanoimprint lithography process. The influences of the reactive-ion etching conditions and deposited Au film thickness to the subwavelength structure profile and its corresponding surface reflectance have been systematically investigated. Under the optimal experimental conditions, the average reflectance of the silicon carbide in the range of 390-784 nm is dramatically suppressed from 21.0 % to 1.9 % after introducing the pseudoperiodic nanostructures. A luminescence enhancement of 226 % was achieved at an emission angle of 20 degrees on the fluorescent silicon carbide. Meanwhile, the angle-resolved photoluminescence study presents a considerable omnidirectional luminescence enhancement.

  • 82.
    Ou, Yiyu
    et al.
    Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Hens, Philip
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kaiser, Michl
    University of Erlangen-Nurnberg, Erlangen, Germany .
    Wellmann, Peter
    University of Erlangen-Nurnberg, Erlangen, Germany.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Broadband and omnidirectional light harvesting enhancement of fluorescent SiC2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 7, p. 7575-7579Article in journal (Refereed)
    Abstract [en]

    In the present work, antireflective sub-wavelength structures have been fabricated on fluorescent 6H-SiC to enhance the white light extraction efficiency by using the reactive-ion etching method. Broadband and omnidirectional antireflection characteristics show that 6H-SiC with antireflective sub-wavelength structures suppress the average surface reflection significantly from 20.5 % to 1.01 % over a wide spectral range of 390-784 nm. The luminescence intensity of the fluorescent 6H-SiC could be enhanced in the whole emission angle range. It maintains an enhancement larger than 91 % up to the incident angle of 70 degrees, while the largest enhancement of 115.4 % could be obtained at 16 degrees. The antireflective sub-wavelength structures on fluorescent 6H-SiC could also preserve the luminescence spectral profile at a large emission angle by eliminating the Fabry-Perot microcavity interference effect.

  • 83.
    Ou, Yiyu
    et al.
    Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kaiser, Michl
    University of Erlangen-Nuremberg, Germany.
    Wellmann, Peter
    University of Erlangen-Nuremberg, Germany.
    Linnarsson, Margareta
    KTH Royal Institute of Technology, Kista, Sweden.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Fabrication of Broadband Antireflective Sub-Wavelength Structures on Fluorescent SiC2013Conference paper (Refereed)
    Abstract [en]

    Surface nanocones on 6H-SiC have been developed and demonstrated as an effective method of enhancing the light extraction efficiency from fluorescent SiC layers. The surface reflectance, measured from the opposite direction of light emission, over a broad bandwidth range is significantly suppressed from 20.5% to 1.0 % after introducing the sub-wavelength structures. An omnidirectional light harvesting enhancement (>91%), is also achieved which promotes fluorescent SiC as a good candidate of wavelength converter for white light-emitting diodes.

  • 84.
    Ou, Yiyu
    et al.
    Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kamiyama, Satoshi
    Meijo University, Nagoya.
    Liu, Chuan
    Technical University of Denmark, Lyngby.
    Berg, Rolf W.
    Technical University of Denmark, Lyngby.
    Linnarsson, Margareta
    School of Information and Communication Technology, Royal Institute of Technology, Kista.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Meijo University, Nagoya .
    Donor-acceptor-pair emission characterization in N-B doped fluorescent in SiC2011In: Optical Materials Express, ISSN 2159-3930, Vol. 1, no 8, p. 1439-1446Article in journal (Refereed)
    Abstract [en]

    In the present work, we investigated donor-acceptor-pair emission in N-B doped fluorescent 6H-SiC, by means of photoluminescence, Raman spectroscopy, and angle-resolved photoluminescence. The photoluminescence results were interpreted by using a band diagram with Fermi-Dirac statistics. It is shown that with N and B concentrations in a range of 1018cm−3 the samples exhibit the most intense luminescence when the concentration difference (n-type) is about 4.6x1018cm−3. Raman spectroscopy studies further verified the doping type and concentrations for the samples. Furthermore, strong luminescence intensity in a large emission angle range was achieved from angle-resolved photoluminescence. The results indicate N-B doped fluorescent SiC as a good wavelength converter in white LEDs applications.

  • 85.
    Ou, Yiyu
    et al.
    Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Linnarsson, Margareta
    Royal Institute of Technology, Kista, Sweden .
    Yakimova, Rositza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Characterization of donor–acceptor-pair emission in fluorescent 6H-SiC2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T148, p. 014003-Article in journal (Refereed)
    Abstract [en]

    We investigated donor–acceptor-pair emission in N–B-doped 6H-SiC samples by using photoluminescence (PL) and angle-resolved PL. It is shown that n-type doping with concentrations larger than 1018 cm−3 is favorable for observing luminescence, and increasing nitrogen results in stronger luminescence. A dopant concentration difference greater than 4×1018 cm−3 is proposed to help achieve intense PL. Angular-dependent PL was observed that was attributed to the Fabry–Pérot microcavity interference effect, and a strong luminescence intensity in a large emission angle range was also achieved. The results indicate that N–B-doped fluorescent SiC is a good wavelength converter in white LED applications.

  • 86.
    Ou, Yiyu
    et al.
    Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Liu, Chuan
    Technical University of Denmark, Lyngby.
    Berg, Rolf W.
    Technical University of Denmark, Lyngby.
    Linnarsson, Margareta
    Kamiyama, Satoshi
    Meijo University, Nagoya, Japan.
    Lu, Zhaoyue
    Technical University of Denmark, Lyngby.
    Yakimova, Rositza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Photoluminescence and Raman spectroscopy characterization of boron and nitrogen-doped 6H silicon carbide2012Conference paper (Refereed)
    Abstract [en]

    Nitrogen-boron doped 6H-SiC epilayers grown on low off-axis 6H-SiC substrates have been characterized by photoluminescence and Raman spectroscopy. The photoluminescence results show that a doping larger than 1018 cm-3 is favorable to observe the luminescence and addition of nitrogen is resulting in an increased luminescence. A dopant concentration difference larger than 4x1018 cm-3 is proposed to achieve intense photoluminescence. Raman spectroscopy further confirmed the doping type and concentrations for the samples. The results indicate that N-B doped SiC is being a good wavelength converter in white LEDs applications.

  • 87.
    Ou, Yiyu
    et al.
    Department of Photonics Engineering, Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Rositza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Haiyan
    Department of Photonics Engineering, Technical University of Denmark, Lyngby.
    Omnidirectional luminescence enhancement of fluorescent SiC via pseudoperiodic antireflective subwavelength structures2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 18, p. 3816-3818Article in journal (Refereed)
    Abstract [en]

    In the present work, an approach of fabricating pseudoperiodic antireflective subwavelength structures (ARS) on fluorescent SiC by using self-assembled etch mask is demonstrated. By applying the pseudoperiodic (ARS), the average surface reflectance at 6° incidence over the spectral range of 390–785 nm is dramatically suppressed from 20.5% to 1.62%, and the hydrophobic surface with a large contact angle of 98° is also achieved. The angle-resolved photoluminescence study presents a considerable omnidirectional luminescence enhancement with an integral intensity enhancement of 66.3% and a fairly preserved spatial emission pattern.

  • 88.
    Ou, Yiyu
    et al.
    Technical University of Denmark.
    Zhu, Xiaolong
    Technical University of Denmark.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Mortensen, N. Asger
    Technical University of Denmark.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Xiao, Sanshui
    Technical University of Denmark.
    Ou, Haiyan
    Technical University of Denmark.
    Broadband Antireflection and Light Extraction Enhancement in Fluorescent SiC with Nanodome Structures2014In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, p. 4662-Article in journal (Refereed)
    Abstract [en]

    We demonstrate a time-efficient and low-cost approach to fabricate Si3N4 coated nanodome structures in fluorescent SiC. Nanosphere lithography is used as the nanopatterning method and SiC nanodome structures with Si3N4 coating are formed via dry etching and thin film deposition process. By using this method, a significant broadband surface antireflection and a considerable omnidirectional luminescence enhancement are obtained. The experimental observations are then supported by numerical simulations. It is believed that our fabrication method will be well suitable for large-scale production in the future.

  • 89.
    Pallon, J.
    et al.
    Lund University, Sweden.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Graphens AB, Teknikringen 1F, SE-58330 Linkoping, Sweden.
    Wang, Q.
    ACREO Swedish ICT AB, Sweden.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Graphens AB, Teknikringen 1F, SE-58330 Linkoping, Sweden.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Graphens AB, Teknikringen 1F, SE-58330 Linkoping, Sweden.
    Elfman, M.
    Lund University, Sweden.
    Kristiansson, P.
    Lund University, Sweden.
    Nilsson, E. J. C.
    Lund University, Sweden.
    Ros, L.
    Lund University, Sweden.
    Ion beam evaluation of silicon carbide membrane structures intended for particle detectors2016In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 371, p. 132-136Article in journal (Refereed)
    Abstract [en]

    Thin ion transmission detectors can be used as a part of a telescope detector for mass and energy identification but also as a pre-cell detector in a microbeam system for studies of biological effects from single ion hits on individual living cells. We investigated a structure of graphene on silicon carbide (SiC) with the purpose to explore a thin transmission detector with a very low noise level and having mechanical strength to act as a vacuum window. In order to reach very deep cavities in the SiC wafers for the preparation of the membrane in the detector, we have studied the Inductive Coupled Plasma technique to etch deep circular cavities in 325 mu m prototype samples. By a special high temperature process the outermost layers of the etched SiC wafers were converted into a highly conductive graphitic layer. The produced cavities were characterized by electron microscopy, optical microscopy and proton energy loss measurements. The average membrane thickness was found to be less than 40 mu m, however, with a slightly curved profile. Small spots representing much thinner membrane were also observed and might have an origin in crystal defects or impurities. Proton energy loss measurement (also called Scanning Transmission Ion Microscopy, STIM) is a well suited technique for this thickness range. This work presents the first steps of fabricating a membrane structure of SiC and graphene which may be an attractive approach as a detector due to the combined properties of SiC and graphene in a monolithic materials structure. (C) 2015 Elsevier B.V. All rights reserved.

  • 90. Paskaleva, A
    et al.
    Ciechonski, Rafal
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Atanassova, E
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Characterization of 4H-SiC MOS structures with Al2O3 as gate dielectric2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483, p. 709-712Conference paper (Refereed)
    Abstract [en]

    The electrical properties of Al2O3 as a gate dielectric in MOS structures based on n- and p-type 4H-SiC grown by sublimation method have been investigated and compared to the properties of similar structures utilizing SiO2. The electrically active defects in the structures are studied by CV method. The results show that the type as well as spatial and energy distribution of defects in Al2O3/SiC and SiO2/SiC samples are different. The structures with Al2O3 on p-type 4H-SiC demonstrate much better C-V characteristics than the p-type 4H-SiC/SiO2 structures.

  • 91. Paskaleva, A
    et al.
    Ciechonski, Rafal
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Atanassova, E
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Electrical behavior of 4H-SiC metal-oxide-semiconductor structures with Al2O3 as gate dielectric2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 12, p. 124507-Article in journal (Refereed)
    Abstract [en]

    The electrical properties of Al2O3 as a gate dielectric in metal-oxide-semiconductorstructures based on n- and p-type 4H-SiC grown by sublimation method have been investigated and compared to the properties of similar structures utilizing SiO2. The electrically active defects in the structures are studied by capacitance–voltage (C–V) and current–voltage (I–V) methods. The results show that the type as well as spatial and energy distributions of defects in Al2O3/SiC and SiO2/SiC samples are different. The structures with Al2O3 on p-type 4H-SiC demonstrate much better electrical characteristics than the p-type 4H-SiC/SiO2 structures. It is demonstrated that the conduction process in the former is governed by Fowler–Nordheim electron tunneling from the Al gate whereas in the latter the hole tunneling from SiC is the more probable process. This difference combined with the higher defect density in p-type SiC/SiO2 structures defines the higher leakage currents compared to the structures utilizing Al2O3.

  • 92.
    Patricia, Carvalho
    et al.
    SINTEF Materials Physics, Oslo, Norway; University of Lisbon, Instituto Superior Tecnico, Lisbon, Portugal.
    Annett, Thørgesen
    SINTEF Materials Physics, Oslo, Norway.
    Quanbao, Ma
    University of Oslo, Department of Physics, Oslo, Norway.
    Daniel Nielsen, Wright
    SINTEF Instrumentation, Oslo, Norway.
    Spyros, Diplas
    SINTEF Materials Physics, Oslo, Norway; University of Oslo, Department of Chemistry, Oslo, Norway.
    Augustinas, Galeckas
    University of Oslo, Department of Physics, Oslo, Norway.
    Alexander, Azarov
    University of Oslo, Department of Physics, Oslo, Norway.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sun, Jianwu W.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Bengt Gunnar, Svensson
    University of Oslo, Department of Physics, Oslo, Norway.
    Ole Martin, Løvvik
    SINTEF Materials Physics, Oslo, Norway; University of Oslo, Department of Physics, Oslo, Norway.
    Boron-doping of cubic SiC for intermediate band solar cells: a scanning transmission electron microscopy study2018In: SciPost Physics, ISSN 2542-4653, Vol. 5, no 3, p. 1-17Article in journal (Refereed)
    Abstract [en]

    Boron (B) has the potential for generating an intermediate band in cubic silicon carbide (3C-SiC), turning this material into a highly efficient absorber for single-junction solar cells. The formation of a delocalized band demands high concentration of the foreign element, but the precipitation behavior of B in the 3C polymorph of SiC is not well known. Here, probe-corrected scanning transmission electron microscopy and secondary-ion mass spectrometry are used to investigate precipitation mechanisms in B-implanted 3C-SiC as a function of temperature. Point-defect clustering was detected after annealing at 1273 K, while stacking faults, B-rich precipitates and dislocation networks developed in the 1573 - 1773 K range. The precipitates adopted the rhombohedral B13C2 structure and trapped B up to 1773 K. Above this temperature, higher solubility reduced precipitation and free B diffused out of the implantation layer. Dopant concentrations E19 at.cm-3 were achieved at 1873 K.

  • 93.
    Pecz, B
    et al.
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Outokumpu Semitron AB, S-17824 Ekero, Sweden Swedish Space Corp, S-17104 Solna, Sweden Royal Inst Technol, S-16440 Kista, Sweden.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Lockowandt, C
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Outokumpu Semitron AB, S-17824 Ekero, Sweden Swedish Space Corp, S-17104 Solna, Sweden Royal Inst Technol, S-16440 Kista, Sweden.
    Radamson, H
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Outokumpu Semitron AB, S-17824 Ekero, Sweden Swedish Space Corp, S-17104 Solna, Sweden Royal Inst Technol, S-16440 Kista, Sweden.
    Radnoczi, G
    Hungarian Acad Sci, Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Outokumpu Semitron AB, S-17824 Ekero, Sweden Swedish Space Corp, S-17104 Solna, Sweden Royal Inst Technol, S-16440 Kista, Sweden.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Structural investigation of SiC epitaxial layers grown under microgravity and on-ground conditions1999In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 357, no 2, p. 137-143Article in journal (Refereed)
    Abstract [en]

    Thick 4H-, and 6H-SiC epitaxial layers have been grown by LPE from Si-Sc-C solvent at microgravity conditions during a space experiment, as well as on-ground. The samples are characterised by cross-sectional TEM and HRXRD. Layers grown at microgravity are relatively defect free, although their surfaces are always stepped. Control samples grown on-ground have similar surface appearance, but contain scandium carbide precipitates, nanopipes, micropipes and/or cavities as verified by TEM. However, none of the aforementioned defects was traced in the layers grown at microgravity conditions. So, samples grown at space microgravity conditions are superior in their defect structure to those ones grown on the ground. The defects called nanopipes can be described as empty pipes of about 200 nm diameter traversing the layer in the [0001] (growth) direction. The steps in the microgravity and on-ground samples have facets of {104} type crystallographic planes both in 6H-, and 4H-SiC. We suggest, that those facets are formed and preferred during growth due to a possible mechanism of decreasing the high energy of the growing Si terminated (0001) surface. (C) 1999 Elsevier Science S.A. All rights reserved.

  • 94.
    Pecz, B
    et al.
    Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Swedish Space Corp, S-17104 Solna, Sweden.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Lockowandt, C
    Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Swedish Space Corp, S-17104 Solna, Sweden.
    Radnoczi, G
    Res Inst Tech Phys & Mat Sci, H-1525 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Swedish Space Corp, S-17104 Solna, Sweden.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Structure of SiC layers grown by LPE in microgravity and on-ground conditions1999In: Institute of Physics Conference Series, ISSN 0951-3248, E-ISSN 2154-6630, no 164, p. 243-246Article in journal (Refereed)
    Abstract [en]

    High quality, hexagonal SiC layers have been grown in microgravity conditions and on-ground as well. The surface of the layers is always stepped. The dislocation density of the layers is increased closer to the surface. Scandium carbide precipitates, nanopipes and cavities were found in the SiC layers grown on-ground, but none of them were traced in the layers grown under microgravity conditions.

  • 95.
    Petoral, Rodrigo Jr
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Yazdi, Gholamreza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Vahlberg, Cecilia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Surface Functionalization of SiC for Biosensor Applications2007In: ECSCRM 2006,2006, Material Science Forum, vol 556-557: Trans Tech Publications , 2007, p. 957-Conference paper (Refereed)
  • 96. Pirri, CF
    et al.
    Porro, S
    Ferrero, S
    Celasco, E
    Guastella, S
    Scaltrito, L
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ciechonski, Rafal
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    De Angelis, S
    Crippa, D
    Growth, morphological and structural characterization of silicon carbide epilayers for power electronic devices applications2005In: Crystal research and technology (1981), ISSN 0232-1300, E-ISSN 1521-4079, Vol. 40, no 10-Nov, p. 964-966Article in journal (Refereed)
    Abstract [en]

    Silicon carbide (SiC) is a wide band gap semiconductor, interesting for its physical properties such as high breakdown field, high saturated drift velocity and high thermal conductivity, which has been intensively studied in the last years. Although the high potentiality of this material, the SiC technology shows at the moment some limitations, indeed, the reliability of SiC-based devices is strictly correlated to the defects present in the crystalline structure. 4H-SiC epilayers were grown by Hot Wall Chemical Vapor Deposition (at 1600 degrees C) and by Sublimation techniques (at 2000 degrees C). A surface investigation of the epilayers has been performed finding particular physical finger-prints correlated with several kind of defects aimed at giving an important feedback to the epitaxial growth processes. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 97. Polychroniadis, E
    et al.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology.
    Stoemenos, J
    Microstructural characterization of very thick freestanding 3C-SiC wafers2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 263, no 1-4, p. 68-75Article in journal (Refereed)
    Abstract [en]

    The microstructural characteristics of 300μm thick freestanding 3C-SiC wafers, provided by HOYA, were studied by transmission electron microscopy. The observed defects were mainly stacking faults (SFs), microtwins and inversion domain boundaries (IDBs). The defect density is reduced fast from the SiC/Si interface up to the first 20μm, and then it remains constant up to the surface, suggesting a defect growth and elimination mechanism. At the uppermost part of the film the distribution of the SFs is very inhomogeneous, large zones were completely free of SFs with the SFs mainly concentrating in areas where IDBs exist and their density was lower by more than one order of magnitude than the SFs. 3C-SiC 40μm thick layers were grown on the wafers by sublimation epitaxy. Optical micrographs of these layers exhibit macro-features different from the substrate, but still indicating large bands of SFs.

  • 98.
    Porro, Samuele
    et al.
    Department of Physics, Polytechnic of Torino, Torino, Italy.
    Ciechonski, Rafal
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Electrical Analysis and Interface States Evaluation of of Ni Schottky diodes on 4H-SiC thick epilayers2005In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 202, no 13, p. 2508-2514Article in journal (Refereed)
    Abstract [en]

    This work has been focused on characterization of thick 4H-SiC layers produced by sublimation epitaxy. Nickel Schottky contacts have been fabricated in order to characterize the grown material and evaluate the interfacial layer between metal and semiconductor. The characterization study includes current-voltage and capacitance-voltage high temperature measurements, from which Schottky barrier, net donor concentration and on-state resistance values have been extracted. The diodes show a typical behavior of J-V and C-V curves with temperature, with Schottky barrier heights of 1.3 eV ÷ 1.4 eV and net donor concentration of 4 × 1015 cm-3 ÷ 1 × 1016 cm-3. From the Bardeen's model on reverse J-V, the density of states of the interfacial layer has been estimated to 7 × 1011 eV-1 cm-2 ÷ 8 × 1011 eV-1 cm-2, a value that is similar to the density of states of oxide layers in deliberated MOS structures realized on the same epilayers.

  • 99.
    Raback, P
    et al.
    Ctr Sci Comp, FIN-02101 Espoo, Finland Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Okmet AB, SE-17824 Ekero, Sweden Helsinki Univ Technol, Phys Lab, FIN-02015 Helsinki, Finland.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Nieminen, R
    Ctr Sci Comp, FIN-02101 Espoo, Finland Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Okmet AB, SE-17824 Ekero, Sweden Helsinki Univ Technol, Phys Lab, FIN-02015 Helsinki, Finland.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Considerations on the crystal morphology in the sublimation growth of SiC2000In: Materials Science Forum, Vols. 338-343, Trans Tech Publications Inc., 2000, Vol. 338-3, p. 95-98Conference paper (Refereed)
    Abstract [en]

    In this paper the shape evolution of SiC source and seed is studied with simulations. Some basic geometries and temperature distributions are investigated. Also the condition for stable growth is discussed.

  • 100.
    Rankl, Dominik
    et al.
    Crystal Growth Lab, University of Erlangen.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Wellmann, Peter
    Crystal Growth Lab, University of Erlangen.
    Quantitative Study on the Role of Supersaturation during Sublimation Growth on the Yield of 50 mm diameter 3C-SiC2015In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 821, p. 77-80Article in journal (Refereed)
    Abstract [en]

    We have investigated the growth of 3C-SiC using sublimation growth in the temperature range from 1800°C to 1950°C. The supersaturation was determined using numerical modeling of the temperature field and gas phase composition by applying quasi-equilibrium thermodynamic conditions. Analysis of the 3C-SiC yield was carried out by optical microscopy, optical absorption, Raman spectroscopy and x-ray analysis. Quantitative data on supersaturation are compared with most stable 3C-SiC nucleation and growth condition. Finally the application to large area growth in a physical vapor transport growth reactor is briefly addressed.

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