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  • 1. Aavikko, R.
    et al.
    Saarinen, K.
    Magnusson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Clustering of Vacancies in Semi-Insulating SiC Observed with Positron Spectroscopy2006Inngår i: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, s. 575-578Konferansepaper (Fagfellevurdert)
  • 2. Aavikko, R
    et al.
    Saarinen, K
    Magnusson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Observation of vacancy clusters in HTCVD grown SiC2005Inngår i: Materials Science Forum, Vols. 483-485, 2005, Vol. 483, s. 469-472Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Positron lifetime spectroscopy was used to study defects in semi-insulating (SI) silicon carbide (SiC) substrates grown by high-temperature chemical vapor deposition (HTCVD). The measured positron lifetime spectra can be decomposed into two components, of which the longer corresponds to vacancy clusters. We have carried out atomic superposition calculations to estimate the size of these clusters.

  • 3. Aavikko, R.
    et al.
    Saarinen, K.
    Tuomisto, F.
    Magnusson, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Nguyen, Son Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Clustering of vacancy defects in high-purity semi-insulating SiC2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, nr 8, s. 085208-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity in both as-grown and annealed materials. Our results suggest that Si-vacancy-related complexes electrically compensate the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity. © 2007 The American Physical Society.

  • 4. Aleksiejunas, R.
    et al.
    Jarasiunas, K.
    Kakanakova-Georgieva, Anelia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Characterization of GaN/SiC epilayers by picosecond four-wave mixing technique2004Inngår i: Physica Scripta, Vol. T114, 2004, Vol. T114, s. 231-232Konferansepaper (Fagfellevurdert)
  • 5.
    Andersson, Christer M
    et al.
    Microwave Electronics Laboratory, Chalmers University of Technology, Gothenburg.
    Ejebjörk, Niclas
    Microwave Electronics Laboratory, Chalmers University of Technology, Gothenburg.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Andersson, Sven
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Zirath, Herbert
    Microwave Electronics Laboratory, Chalmers University of Technology, Gothenburg.
    Rorsman, Niklas
    Microwave Electronics Laboratory, Chalmers University of Technology, Gothenburg.
    A SiC Varactor With Large Effective Tuning Range for Microwave Power Applications2011Inngår i: IEEE ELECTRON DEVICE LETTERS, ISSN 0741-3106, Vol. 32, nr 6, s. 788-790Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    SiC Schottky diode varactors have been fabricated for use in microwave power applications, specifically the dynamic load modulation of power amplifiers. A custom doping profile has been employed to spread the C(V) over a large bias voltage range, thereby increasing the effective tuning range under large voltage swing conditions. The small-signal tuning range is approximately six, and punch through is reached at a bias voltage of -60 V, while the breakdown voltage is on the order of -160 V. An interdigitated layout is utilized together with a self-aligned Schottky anode etch process to improve the Q-factor at 2 GHz, which is 20 at zero bias and approximately 160 at punch through.

  • 6.
    Aradi, B.
    et al.
    Department of Atomic Physics, Budapest Univ. of Technol. and Econ., Budafoki út 8, Budapest, H-1111, Hungary.
    Deak, P.
    Deák, P., Department of Atomic Physics, Budapest Univ. of Technol. and Econ., Budafoki út 8, Budapest, H-1111, Hungary.
    Nguyen, Tien Son
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Choyke, W.J.
    Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States.
    Devaty, R.P.
    Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States.
    Impurity-controlled dopant activation: Hydrogen-determined site selection of boron in silicon carbide2001Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 79, nr 17, s. 2746-2748Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The geometry and formation energy of substitutional B and Al dopants as well as their complexes with hydrogen have been calculated in 4H-SiC using first-principles methods. Our results show that boron selecting the silicon site and, therefore, getting activated as a shallow acceptor depends on the presence of hydrogen which is promoted into the crystal by boron itself. Without hydrogen, boron would mostly be incorporated at the carbon site. Aluminum does not show this behavior: it always selects the silicon site and is incorporated independently of hydrogen. © 2001 American Institute of Physics.

  • 7. Aradi, B
    et al.
    Deák, P
    Gali, A
    Nguyen, Son Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Diffusion of hydrogen in perfect, p-type doped, and radiation-damaged 4H-SiC2004Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The diffusion of interstitial atomic hydrogen in 4H-SiC was investigated theoretically, using the local density approximation of density functional theory. We have found that the diffusion barrier in the perfect crystal is ≤0.6 eV. Comparing this value with the calculated zero point vibration energy of interstitial hydrogen indicates that hydrogen diffuses very rapidly in perfect portions of the SiC lattice, until it gets trapped. In p-doped (B, Al) material the dissociation of the hydrogen-acceptor complexes is the limiting step in diffusion, with a calculated dissociation energy of 2.5 and 1.6 eV for B+H and Al+H, respectively. In irradiated material the trapping and detrapping of hydrogen by silicon vacancies determines the effective diffusion barrier, which lies between 4.0 and 5.3 eV depending on the Fermi level in p-type and weakly n-type material.

  • 8.
    Aradi, B.
    et al.
    Budapest University of Technology and Economy.
    Gali, A.
    Research Group of the Hungarian Academy of Sciences.
    Deák, P.
    Budapest University of Technology and Economy.
    Lowther, J. E.
    University of the Witwatersrand.
    Son, N. T.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ab initio density-functional supercell calculations of hydrogen defects in cubic SiC2001Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, nr 245202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on ab initio density-functional calculations in supercells of 3C-SiC, the stable configurations of hydrogen and dihydrogen defects have been established. The calculated formation energies are used to give semiquantitative estimates for the concentration of hydrogen in SiC after chemical vapor deposition, low temperature H-plasma anneal, or heat treatment in high temperature hydrogen gas. Vibration frequencies, spin distributions, and occupation levels were also calculated in order to facilitate spectroscopic identification of these defects. (V+nH) complexes are suggested as the origin of some of the signals assigned earlier to pure vacancies. Qualitative extrapolation of our results to hexagonal polytypes explains observed electrical passivation effects of hydrogen.

  • 9.
    Aradi, B
    et al.
    Tech Univ Budapest, Dept Atom Phys, HU-1111 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Gali, Adam
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Deak, P
    Tech Univ Budapest, Dept Atom Phys, HU-1111 Budapest, Hungary Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Nguyen, Tien Son
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Impurity-controlled dopant activation - The role of hydrogen in p-type doping of SiC2002Inngår i: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, s. 561-564Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hydrogen is a natural contaminant of SiC growth processes, and may influence the doping efficiency. Hydrogen incorporation proportional to that of boron was observed during CVD growth while the amount of hydrogen was two orders of magnitude less than the aluminum concentration. Passivation by complex formation with hydrogen has been proven both for Al and B. The experimentally observed reactivation energy of these complexes differ by 0.9 eV. Our ab initio supercell calculations in 4H-SiC indicate, that in the absence of hydrogen, boron is incorporated as isolated substitutional and prefers the carbon site, while under typical CVD conditions boron is incorporated together with hydrogen (in equal amounts), favoring the silicon site. Therefore, the presence of H is advantageous for the activation of B as a shallow acceptor. In contrast to boron, aluminum is incorporated independently of the presence of hydrogen as isolated substitutional at the silicon site. The calculated difference between the dissociation of the stable dopant plus hydrogen complexes agrees very well with experiments. Vibration frequencies for the dopant complexes have been also calculated.

  • 10.
    Aradi, B.
    et al.
    Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary.
    Gali, Adam
    Department of Atomic Physics, Budapest Univ. of Technol./Economics, Budafoki út 8, H-1111 Budapest, Hungary.
    Deak, P.
    Deák, P., Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary.
    Nguyen, Tien Son
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Passivation of p-type dopants in 4H-SiC by hydrogen2001Inngår i: Physica B, Vols. 308-310, 2001, Vol. 308-310, s. 722-725Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Experimental investigations showed passivation of the p-type dopants B and Al in 4H-SiC by the formation of B+H and Al+H complexes. The dissociation energies of these complexes differed by 0.9 eV. Ab initio supercell calculations have been performed to investigate the interaction of H with B and Al in hexagonal 4H-SiC. The total energy, geometry and electronic structure of the possible complexes have been determined. Site dependencies have also been investigated. The most stable configurations were found with H at a bond center site next to B at the Si site, and with H at the antibonding site of a carbon atom which is first neighbor to Al at a Si site. Both the BSi+HBC and the AlSi+HAB(C) complexes turned out to be electrically inactive. The different structure of the passivated complexes explains the observed difference in their dissociation energy: the calculated difference of the binding energies of these complexes is 0.9 eV, which agrees well with the experimental finding. © 2001 Elsevier Science B.V. All rights reserved.

  • 11.
    Arslan, Engin
    et al.
    Bilkent University, Turkey .
    Cakmakyapan, Semih
    Bilkent University, Turkey .
    Kazar, Ozgur
    Bilkent University, Turkey .
    Butun, Serkan
    Bilkent University, Turkey .
    Bora Lisesivdin, Sefer
    Gazi University, Turkey .
    Cinel, Neval A.
    Bilkent University, Turkey .
    Ertas, Gulay
    Bilkent University, Turkey .
    Ardali, Sukru
    Anadolu University, Turkey .
    Tiras, Engin
    Anadolu University, Turkey .
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ozbay, Ekmel
    Bilkent University, Turkey .
    SiC Substrate Effects on Electron Transport in the Epitaxial Graphene Layer2014Inngår i: ELECTRONIC MATERIALS LETTERS, ISSN 1738-8090, Vol. 10, nr 2, s. 387-391Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hall effect measurements on epitaxial graphene (EG) on SiC substrate have been carried out as a function of temperature. The mobility and concentration of electrons within the two-dimensional electron gas (2DEG) at the EG layers and within the underlying SiC substrate are readily separated and characterized by the simple parallel conduction extraction method (SPCEM). Two electron carriers are identified in the EG/SiC sample: one high-mobility carrier (3493 cm(2)/Vs at 300 K) and one low-mobility carrier (1115 cm(2)/Vs at 300 K). The high mobility carrier can be assigned to the graphene layers. The second carrier has been assigned to the SiC substrate.

  • 12.
    Azam, Sher
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Jonsson, R.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Wahab, Qamar Ul
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Performance of SiC Microwave Transistors in Power Amplifiers2008Inngår i: Proc. of MRS Symposium on wide bandgap semiconductor electronics 8, 2008, s. 203-208Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of SiC microwave power transistors is studied in fabricated class-AB power amplifiers and class-C switching power amplifier using physical structure of an enhanced version of previously fabricated and tested SiC MESFET. The results for pulse input in class-C at 1 GHz are; efficiency of 71.4 %, power density of 1.0 W/mm. The switching loss was 0.424 W/mm. The results for two class-AB power amplifiers are; the 30-100 MHz amplifier showed 45.6 dBm (∼ 36 W) output powers at P1dB, at 50 MHz. The power added efficiency (PAE) is 48 % together with 21 dB of power gain. The maximum output power at P1dB at 60 V drain bias and Vg= -8.5 V was 46.7 dBm (∼47 W). The typical results obtained in 200-500 MHz amplifier are; at 60 V drain bias the P1dB is 43.85 dBm (24 W) except at 300 MHz where only 41.8 dBm was obtained. The maximum out put power was 44.15 dBm (26 W) at 500 MHz corresponding to a power density of 5.2 W/mm. The PAE @ P1dB [%] at 500 MHz is 66 %.

  • 13.
    Bergman, JP
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Jakobsson, H
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Carlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Magnusson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Sridhara, S
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Pozina, Galia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Lendenmann, H
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Characterisation and defects in silicon carbide2002Inngår i: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work we present experimental results of several defects in 4H Sic that are of interest both from a fundamental and physical point of view. And also of great importance for device applications utilizing the Sic material. These defects include the temperature stable so called D1 defect, which is created after irradiation. This optical emission has been identified as an isoelectronic defect bound at a hole attractive pseudodonor, and we have been able to correlate this to the electrically observed hole trap HS1 seen in minority carrier transient spectroscopy (MCTS). It also includes the UD1 defect observed using absorption and FTIR and which is believed to be responsible for the semi-insulating behavior of material grown by the High temperature, HTCVD technique. Finally, we have described the formation and proper-ties of critical, generated defect in high power Sic bipolar devices. This is identified as a stacking fault in the Sic basal plane, using mainly white beam synchrotron Xray topography. The stacking fault is both optically and electrically active, by forming extended local potential reduction of the conduction band.

  • 14.
    Bergman, Peder
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Radial Variation of Measured Carrier Lifetimes in Epitaxial Layers Grown with Wafer Rotation2012Inngår i: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 289-292Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this report we present homoepitaxial growth of 4H-SiC on the Si-face of nominally on-axis substrates with diameter up to 100 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers. Also, local variations in carrier lifetime are different from standard off-cut epilayers. The properties of layers were studied with more focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneous surface morphology and different growth mechanisms.

  • 15.
    Bergman, Peder
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ellison, A.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Storasta, Liutauras
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    The role of defects on optical and electrical properties of SiC2000Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work we describe some of the defects in SiC observable using different optical characterisation techniques. This includes photoluminescence measurements to determine the presence of different defects. We also show that optical techniques can be developed for mapping characterisation, which are useful both for routine measurements and for determine spatial variations and presence of defects over larger areas. One such example is the lifetime mappings on epitaxial layers on entire wafers, which has shown the importance of structural defects replicated into the epitaxial layer. Optical measurements have also been correlated to structural measurements from X-ray topography to demonstrate the importance of the structural defects

  • 16.
    Bergman, Peder
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Carlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Sridhara, S.
    Magnusson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Defects in 4H silicon carbide2001Inngår i: Physica B, Vols. 308-310, 2001, Vol. 308-310, s. 675-679Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present experimental results related to several different intrinsic defects that in different ways influence the material properties and are therefore technologically important defects. This includes the so-called D1 defect which is created after irradiation and which is temperature stable. From the optical measurements we were able to identify the D1 bound exciton as an isoelectronic defect bound at a hole attractive pseudo-donor, and we have been able to correlate this to the electrically observed hole trap HS1 seen in minority carrier transient spectroscopy (MCTS). Finally, we describe the formation and properties of a critical, generated defect in high power SiC bipolar devices. It is identified as a stacking fault in the SiC basal plane. It can be seen as a local reduction of the carrier lifetime, in triangular or rectangular shape, which explains the enhanced forward voltage drop in the diodes. The entire stacking faults are also optically active as can be seen as dark triangles and rectangles in low temperature cathodo-luminescence, and the fault and their bounding partial dislocations are seen and identified using synchrotron topography. © 2001 Elsevier Science B.V. All rights reserved.

  • 17.
    Bergman, Peder
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    ul-Hassan, Jawad
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Godignon, P.
    Brosselard, P.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Improved SiC Epitaxial Material for Bipolar Applications2008Inngår i: Proc. of MRS Spring Meeting 2008, 2008, s. D05-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Epitaxial growth on Si-face nominally on-axis 4H-SiC substrates has been performed using horizontal Hot-wall chemical vapor deposition system. The formation of 3C inclusions is one of the main problem with growth on on-axis Si-face substrates. In situ surface preparation, starting growth parameters and growth temperature are found to play a vital role in the epilayer polytype stability. High quality epilayers with 100% 4H-SiC were obtained on full 2″ substrates. Different optical and structural techniques were used to characterize the material and to understand the growth mechanisms. It was found that the replication of the basal plane dislocation from the substrate into the epilayer can be eliminated through growth on on-axis substrates. Also, no other kind of structural defects were found in the grown epilayers. These layers have also been processed for simple PiN structures to observe any bipolar degradation. More than 70% of the diodes showed no forward voltage drift during 30 min operation at 100 A/cm2.

  • 18.
    Bergsten, Johan
    et al.
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Chen, Jr-Tai
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Sebastian
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Thorsell, Mattias
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Rorsman, Niklas
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Impact of AlGaN/GaN interface sharpness on HEMT performanceManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The impact of the design and sharpness of the AlGaN/GaN interface in GaN-based HEMTs is investigated. Three structures with different AlGaN/GaN interface properties were grown with hot-wall MOCVD. One structure has a 2-nmthick AlN exclusion layer in between the AlGaN and the GaN, while the other two differ in their sharpness of the Al transition at the AlGaN/GaN interface. The structures with AlN exclusion layer and optimized sharpness of the interface show similar electron mobilities (1760 and 1740 cm2/Vs). HEMTs were processed and evaluated. Gated Hall-measurements indicate that the sharper interface maintains a higher mobility when the electrons are close to the interface compared both to the AlNexclusion layer and the non-optimized structure. The higher mobility manifests as lower parasitic resistance yielding better DC and high frequency performance. Pulsed IV measurements indicate that the sharper interface provide less dispersive effects compared both to the AlN exclusion layer and the optimized interface.

  • 19.
    Bergsten, Johan
    et al.
    Chalmers, Sweden.
    Chen, Jr-Tai
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Sebastian
    Chalmers, Sweden.
    Malmros, Anna
    Chalmers, Sweden.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Thorsell, Mattias
    Chalmers, Sweden.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Rorsman, Niklas
    Chalmers, Sweden.
    Performance Enhancement of Microwave GaN HEMTs Without an AlN-Exclusion Layer Using an Optimized AlGaN/GaN Interface Growth Process2016Inngår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 63, nr 1, s. 333-338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impact of the sharpness of the AlGaN/GaN interface in high-electron mobility transistors (HEMTs) is investigated. Two structures, one with an optimized AlGaN/GaN interface and another with an unoptimized, were grown using hot-wall metal-organic chemical vapor deposition. The structure with optimized sharpness of the interface shows electron mobility of 1760 cm(2)/V . s as compared with 1660 cm(2)/V . s for the nonoptimized interface. Gated Hall measurements indicate that the sharper interface maintains higher mobility when the electrons are close to the interface compared with the nonoptimized structure, indicating less scattering due to alloy disorder and interface roughness. HEMTs were processed and evaluated. The higher mobility manifests as lower parasitic resistance yielding a better dc and high-frequency performance. A small-signal equivalent model is extracted. The results indicate a lower electron penetration into the buffer in the optimized sample. Pulsed-IV measurements imply that the sharper interface provides less dispersive effects at large drain biases. We speculate that the mobility enhancement seen AlGaN/AlN/GaN structures compared with the AlGaN/GaN case is not only related to the larger conduction band offset but also due to a more welldefined interface minimizing scattering due to alloy disorder and interface roughness.

  • 20.
    Bergsten, Johan
    et al.
    Chalmers, Gothenburg, Sweden.
    Li, Xun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Nilsson, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Danielsson, Örjan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Rorsman, Niklas
    Chalmers, Gothenburg, Sweden.
    AlGaN/GaN high electron mobility transistors with intentionally doped GaN buffer using propane as carbon precursor2016Inngår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 55, s. 05FK02-1-05FK02-4, artikkel-id 05FK02Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on a heterostructure grown by metalorganic chemical vapor deposition using analternative method of carbon (C) doping the buffer are characterized. C-doping is achieved by using propane as precursor, as compared to tuningthe growth process parameters to control C-incorporation from the gallium precursor. This approach allows for optimization of the GaN growthconditions without compromising material quality to achieve semi-insulating properties. The HEMTs are evaluated in terms of isolation anddispersion. Good isolation with OFF-state currents of 2 ' 10%6A/mm, breakdown fields of 70V/μm, and low drain induced barrier lowering of0.13mV/V are found. Dispersive effects are examined using pulsed current–voltage measurements. Current collapse and knee walkout effectslimit the maximum output power to 1.3W/mm. With further optimization of the C-doping profile and GaN material quality this method should offer aversatile approach to decrease dispersive effects in GaN HEMTs.

  • 21.
    Bernardin, Evans
    et al.
    University of South Florida, Tampa, FL, U.S.A..
    Frewin, Christopher L.
    University of Texas at Dallas, Dallas, TX, U.S.A.
    Dey, Abhishek
    University of South Florida, Tampa, FL, U.S.A..
    Everly, Richard
    University of South Florida, Tampa, FL, U.S.A..
    Ul Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Pancrazio, Joe
    University of Texas at Dallas, Dallas, TX, U.S.A.
    Saddow, Stephen E.
    University of South Florida, Tampa, FL, U.S.A..
    Development of an all-SiC neuronal interface device2016Inngår i: MRS Advances, ISSN 2059-8521, Vol. 1, nr 55, s. 3679-3684Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The intracortical neural interface (INI) is a key component of brain machine interfaces (BMI) which offer the possibility to restore functions lost by patients due to severe trauma to the central or peripheral nervous system. Unfortunately today’s neural electrodes suffer from a variety of design flaws, mainly the use of non-biocompatible materials based on Si or W with polymer coatings to mask the underlying material. Silicon carbide (SiC) is a semiconductor that has been proven to be highly biocompatible, and this chemically inert, physically robust material system may provide the longevity and reliability needed for the INI community. The design, fabrication, and preliminary testing of a prototype all-SiC planar microelectrode array based on 4H-SiC with an amorphous silicon carbide (a-SiC) insulator is described. The fabrication of the planar microelectrode was performed utilizing a series of conventional micromachining steps. Preliminary data is presented which shows a proof of concept for an all-SiC microelectrode device.

  • 22.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Gällström, Andreas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Leone, Stefano
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Deep levels in tungsten doped n-type 3C-SiC2011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 15, s. 152104-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 23.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Leone, Stefano
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lin, Y.-C.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Gällström, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Deep levels in iron doped n- and p-type 4H-SiC2011Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, s. 123701-1-123701-5Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 24.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Isoya, J
    University of Tsukuba.
    Morishita, N
    Japan Atomic Energy Agency.
    Ohshima, T
    Japan Atomic Energy Agency.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bistable defects in low-energy electron irradiated n-type 4H-SiC2010Inngår i: PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS, ISSN 1862-6254, Vol. 4, nr 8-9, s. 227-229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epitaxial n-type 4H-SiC layers were irradiated at room temperature by low-energy electrons. During the annihilation process of the irradiation induced defects EH I and EH3, three new bistable centers, labeled EB centers, were detected in the DLTS spectrum. The reconfigurations of the EB centers (I -andgt; II and II -andgt; I) take place at room temperature with a thermal reconfiguration energy of about 0.95 eV. The threshold energy for moving the Si atom from its site in the SiC crystal structure is higher than the applied irradiation energy; therefore, the EB centers are attributed to carbon related complex defects.

  • 25.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Isoya, J
    University of Tsukuba, Japan .
    Morishita, N
    Japan Atom Energy Agency, Japan .
    Ohshima, T
    University of Tsukuba, Japan .
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Capacitance transient study of a bistable deep level in e(-)-irradiated n-type 4H-SiC2012Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, nr 45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using capacitance transient techniques, a bistable centre, called FB centre here, was observed in electron irradiated 4H-SiC. In configuration A, the deep level known as EH5 (E-a = E-C - 1.07 eV) is detected in the deep level transient spectroscopy spectrum, whereas for configuration B no obvious deep level is observed in the accessible part of the band gap. Isochronal annealing revealed the transition temperatures to be T-A -andgt; B andgt; 730K and for the opposite process T-B -andgt; A approximate to 710 K. The energy needed to conduct the transformations were determined to be E-A(A -andgt; B) = (2.1 +/- 0.1) eV and E-A(B -andgt; A) = (2.3 +/- 0.1) eV, respectively. The pre-factor indicated an atomic jump process for the opposite transition A -andgt; B and a charge carrier-emission dominated process in the case of B -andgt; A. Minority charge carrier injection enhanced the transformation from configuration B to configuration A by lowering the transition barrier by about 1.4 eV. Since the bistable FB centre is already present after low-energy electron irradiation (200 keV), it is likely related to carbon.

  • 26.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Isoya, J.
    University of Tsukuba.
    Morishita, N.
    Japan Atomic Energy Agency.
    Ohshima, T.
    University of Tsukuba.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Defects in low-energy electron-irradiated n-type 4H-SiC2010Inngår i: Physica Scripta, vol. T141, IOP Publishing , 2010, s. 014006-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The bistable M-center, previously observed in high-energy proton-implanted 4H-SiC, was detected in low-energy electron-irradiated 4H-SiC using deep-level transient spectroscopy (DLTS). Irradiation increased the DLTS signals of the intrinsic defects Z(1/2) and EH6/7 and introduced the frequently observed defects EH1 and EH3. After the M-center is annealed out at about 650K without bias and at about 575K with bias applied to the sample during the annealing process, a new bistable defect in the low temperature range of the DLTS spectrum, the EB-center, evolves. Since low-energy irradiation affects mainly the carbon atoms in SiC, the M-center and the newly discovered EB-center are most probably carbon-related intrinsic defects.

  • 27.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Isoya, Junichi
    University of Tsukuba.
    Morishita, Norio
    Japan Atomic Energy Agency.
    Ohshima, Takeshi
    Japan Atomic Energy Agency.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Metastable defects in low-energy electron irradiated n-type 4H-SiC2010Inngår i: Materials Science Forum, Vols. 645-648, Trans Tech Publications , 2010, Vol. 645-648, s. 435-438Konferansepaper (Fagfellevurdert)
    Abstract [en]

    After low-energy electron irradiation of epitaxial n-type 4H-SiC, the DUES peak amplitudes. of the defects Z(1/2) and EH6/7, which were already observed in as-grown layers, increased and the commonly found peaks EH1 and EH3 appeared. The bistable M-center, previously seen in high-energy proton implanted 4H-SiC, was detected. New bistable defects, the EB-centers, evolved after annealing out of the M-center, and EF3. The reconfiguration energies for one of the two EB-centers were determined to be about 0.96 eV for both transitions: from configuration I to II and from configuration II to I. Since low-energy electron irradiation (less than220 keV) affects mainly the carbon atom in SiC, both the M- and EB-centers are likely to be carbon related defects.

  • 28.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Isoya, Junichi
    Graduate School of Library, Information and Media Science, University of Tsukuba, 1-2 Kasuga,Tsukuba, Ibaraki 305-8850, Japan.
    Morishita, Norio
    Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
    Ohshima, Takeshi
    Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Observation of Bistable Defects in Electron Irradiated N-Type 4H-SiC2011Inngår i: Materials Science Forum Vols. 679-680 (2011) pp 249-252, Trans Tech Publications Inc., 2011, s. 249-252Konferansepaper (Fagfellevurdert)
    Abstract [en]

    DLTS measurements show bistable behavior of the previously reported EH5 peak in low- and high-energy electron irradiation 4H-SiC. Both reconfiguration processes (A ! B and B ! A) take place above 700 ±C. By isothermal annealing, the reconfiguration rates were determined and the reconfiguration energy was calculated to EA = 2.4±0.2 eV. Since the defect is present already after low-energy electron irradiation, which mainly affects the C atom in SiC, the EH5 peak may be related to defects associated with C-vacancies or C-interstitials.

  • 29.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Isoya, J.
    University of Tsukuba.
    Morishita, N.
    Japan Atom Energy Agency.
    Ohshima, T.
    Japan Atom Energy Agency.
    Annealing behavior of the EB-centers and M-center in low-energy electron irradiated n-type 4H-SiC2011Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, nr 10, s. 103703-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    After low-energy electron irradiation of epitaxial n-type 4H-SiC with a dose of 5 x 10(16) cm(-2), the bistable M-center, previously reported in high-energy proton implanted 4H-SiC, is detected in the deep level transient spectroscopy (DLTS) spectrum. The annealing behavior of the M-center is confirmed, and an enhanced recombination process is suggested. The annihilation process is coincidental with the evolvement of the bistable EB-centers in the low temperature range of the DLTS spectrum. The annealing energy of the M-center is similar to the generation energy of the EB-centers, thus partial transformation of the M-center to the EB-centers is suggested. The EB-centers completely disappeared after annealing temperatures higher than 700 degrees C without the formation of new defects in the observed DLTS scanning range. The threshold energy for moving Si atom in SiC is higher than the applied irradiation energy, and the annihilation temperatures are relatively low, therefore the M-center, EH1 and EH3, as well as the EB-centers are attributed to defects related to the C atom in SiC, most probably to carbon interstitials and their complexes.

  • 30.
    Beyer, Franziska
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Leone, Stefano
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Deep levels in hetero-epitaxial as-grown 3C-SiC2010Inngår i: AIP Conference Proceedings, Vol. 1292, 2010, s. 63-66Konferansepaper (Fagfellevurdert)
    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.

  • 31.
    Beyer, Franziska
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Pedersen, Henrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Defects in 4H-SiC Layers Grown by Chloride-based Epitaxy2009Inngår i: Materials Science Forum Vols. 615-617 / [ed] Amador Pérez-Tomás, Trans Tech Publications , 2009, s. 373-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Chloride-based 4H-SiC epitaxial layers were investigated by DLTS, MCTS and PL. The DLTS spectra of the as grown samples showed dominance of the Z1/2 and the EH6/7 peaks. For growth rates exceeding 100 µm/h, an additional peak occurred in the DLTS spectra which can be assigned to the UT1 defect. The shallow and the deep boron complexes as well as the HS1 defect are observed in MCTS measurements. The PL spectra are completely dominated by the near band gap (NBG) emission. No luminescence from donor-acceptor pair occurred. The PL line related to the D1 centre was weakly observed. In the NBG region nitrogen bound exciton (N-BE) and free exciton (FE) related lines could be seen. The addition of chlorine in the growth process gives the advantage of high growth rates without the introduction of additional defects.

  • 32. Bishop, S.M.
    et al.
    Preble, E.A.
    Hallin, Christer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Sarney, W.
    Chang, H.-R.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Jacobson, Henrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Reitmeier, Z.J.
    Wagner, B.P.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Davis, R.F.
    Characterization and comparison of 4H-SiC(112 over-bar 0) and 4H-SiC(0001) 8° off-axis substrates and homoepitaxial films2004Inngår i: Materials Research Society Symposium Proceedings, Vol. 815 Silicon Carbide 2004 - Materials, Processing and Devices,2004, 2004, s. 53-58Konferansepaper (Annet vitenskapelig)
  • 33. Bishop, S.M.
    et al.
    Preble, E.A.
    Hallin, Christer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Jacobson, Henrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Wagner, B.P.
    Reitmeier, Z.J.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Davis, R.F.
    Growth of Homoepitaxial Films on 4H-SiC(11-20)and 8° Off-Axis 4H-SiC(0001) Substrates and their Characterization2004Inngår i: Materials Science Forum, Vols. 457-460, Mater. Sci. Forum, Vol. 457-460: Trans Tech Publications Inc. , 2004, s. 221-Konferansepaper (Fagfellevurdert)
  • 34. Bockstedte, M.
    et al.
    Gali, A.
    Umeda, T.
    Nguyen, Son Tien
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Isoya, J.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Signature of the negative Carbon Vacancy-Antisite complex2006Inngår i: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, s. 539-542Konferansepaper (Fagfellevurdert)
  • 35.
    Booker, Ian D.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Farkas, Ildiko
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ivanov, Ivan G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ul Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Chloride-based SiC growth on a-axis 4H-€“SiC substrates2016Inngår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 480, s. 23-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract SiC has, during the last few years, become increasingly important as a power-device material for high voltage applications. The thick, low-doped voltage-supporting epitaxial layer is normally grown by CVD on 4° off-cut 4H–SiC substrates at a growth rate of 5 – 10 ÎŒ m / h using silane (SiH4) and propane (C3H8) or ethylene (C2H4) as precursors. The concentrations of epitaxial defects and dislocations depend to a large extent on the underlying substrate but can also be influenced by the actual epitaxial growth process. Here we will present a study on the properties of the epitaxial layers grown by a Cl-based technique on an a-axis (90° off-cut from c-direction) 4H–SiC substrate.

  • 36.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Abdalla, Hassan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Karhu, Robin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime2016Inngår i: Physical Review Applied, ISSN 2331-7019, Vol. 6, nr 1, s. 1-15, artikkel-id 014010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a complete analysis of the electron- and hole-capture and -emission processes of the deep levels ON1, ON2a, and ON2b in 4H-SiC and their 6H-SiC counterparts OS1a and OS1b through OS3a and OS3b, which are produced by lifetime enhancement oxidation or implantation and annealing techniques. The modeling is based on a simultaneous numerical fitting of multiple high-resolution capacitance deep-level transient spectroscopy spectra measured with different filling-pulse lengths in n- and p-type material. All defects are found to be double-donor-type positive-U two-level defects with very small hole-capture cross sections, making them recombination centers of low efficiency, in accordance with minority-carrier-lifetime measurements. Their behavior as trapping and weak recombination centers, their large concentrations resulting from the lifetime enhancement oxidations, and their high thermal stability, however, make it advisable to minimize their presence in active regions of devices, for example, the base layer of bipolar junction transistors.

  • 37.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Abdalla, Hassan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska högskolan.
    Lilja, L.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Oxidation induced ON1, ON2a/b defects in 4H-SiC characterized by DLTS2014Inngår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, Trans Tech Publications , 2014, Vol. 778-780, s. 281-284Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The deep levels ON1 and ON2a/b introduced by oxidation into 4H-SiC are characterized via standard DLTS and via filling pulse dependent DLTS measurements. Separation of the closely spaced ON2a/b defect is achieved by using a higher resolution correlation function (Gaver-Stehfest 4) and apparent energy level, apparent electron capture cross section and filling pulse measurement derived capture cross sections are given.

  • 38.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    High-Resolution Time-Resolved Carrier Lifetime and Photoluminescence Mapping of 4H-SiC Epilayers2012Inngår i: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 293-296Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a comparison between time-resolved carrier lifetime mappings of several samples and integrated near band edge intensity photoluminescence mappings using a pulsed laser. High-injection conditions and as-grown material are used, which generally allow for the assumption of a single exponential decay. The photoluminescence intensity under these circumstances is proportional to the carrier lifetime and the mappings can be used to detect lifetime-influencing defects in epilayers and give an estimate of the carrier lifetime variation over the wafer. Several examples for the defect detection capability of the system are given.

  • 39.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Electron and hole capture cross sections of deep levels accessible by DLTS and MCTS in p-type 4H-SiCManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The effective electron (σn(T)) and hole (σn(T)) capture cross sections of the electrically active deep levels HK0, HK2, LB1 and EM1 found in as-grown, high temperature annealed and oxidized p-type 4H-SiC were measured by deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS) and optical-electrical MCTS and DLTS (OE-MCTS and EO-DLTS) in an effort to determine the potential recombination centers in p-type material. Additionally, we also find the D-center, and the deep levels EH6/7, ON1 and ON2 in our samples, while the levels HK1, HK3 and HK4, reported in literature, are always below the detection limit. We further compare deep level concentrations and the timeresolved photoluminescence (TRPL) measured low injection (τLI) in samples annealed at up to 1920 °C. None of the detected deep levels possess σp(T):σn(T) ratios which could enable them to act as efficient recombination centers in the annealed epilayers, where τLI ranges from 1.2·10-6 s to less than 100·10-9 s. However, a clear anti-correlation between τLI and the EH6/7 concentration is found, which is linked to the main lifetime limiting center in n-type material, Z1/2, via their common origin, the carbon vacancy. Due to their large σp(T):σn(T) ratio, the Z1/2 deep levels are not detected by frontside illumination MCTS in p-type material. We thus conclude that the main lifetime limiting deep level(s) in p-type 4HSiC appear to be located in the upper half of the bandgap and are most likely either Z1/2, or other deep levels of intrinsic or partially intrinsic origin with a similar σp(T):σn(T) ratio.

  • 40.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Stenberg, Pontus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Carrier lifetime in p- and n-type 4H-SiCManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Temperature-dependent time-resolved photoluminescence measurements made in the temperature range from 77 K to 1000 K on free-standing as grown n-type 4H-SiC and p-type 4H-SiC epilayers, which are either as-grown or annealed at 1000 °C, 1400 °C or 1700 °C, are analyzed. The development of the instantaneous carrier lifetime over temperature, calculated from the decay curves of all n- and p-type samples, is found to be identical in the entire temperature range. With increasing annealing temperature only the magnitude of the lifetime in p-type 4H-SiC decreases while the trend remains identical to that in the as-grown n-type sample. Annealing thus only increases the density of the main recombination center which appears to control lifetime in as-grown n- and p-type material. The results implies that the lifetime in all samples may be governed by the same intrinsic defect, which we suggest to be Z1/2.

  • 41.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Son, Nguyen Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Stenberg, Pontus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Donor and double donor transitions of the carbon vacancy related EH6/7 deep level in 4H-SiC2016Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, nr 23, artikkel-id 235703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using medium- and high-resolution multi-spectra fitting of deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS), optical O-DLTS and optical-electrical (OE)-MCTS measurements, we show that the EH6∕7 deep level in 4H-SiC is composed of two strongly overlapping, two electron emission processes with thermal activation energies of 1.49 eV and 1.58 eV for EH6 and 1.48 eV and 1.66 eV for EH7. The electron emission peaks of EH7 completely overlap while the emission peaks of EH6 occur offset at slightly different temperatures in the spectra. OE-MCTS measurements of the hole capture cross section σp 0(T) in p-type samples reveal a trap-Auger process, whereby hole capture into the defect occupied by two electrons leads to a recombination event and the ejection of the second electron into the conduction band. Values of the hole and electron capture cross sections σn(T) and σp(T) differ strongly due to the donor like nature of the deep levels and while all σn(T) have a negative temperature dependence, the σp(T) appear to be temperature independent. Average values at the DLTS measurement temperature (∼600 K) are σn 2+(T) ≈ 1 × 10−14 cm2, σn +(T) ≈ 1 × 10−14 cm2, and σp 0(T) ≈ 9 × 10−18 cm2 for EH6 and σn 2+(T) ≈ 2 × 10−14 cm2, σn +(T) ≈ 2 × 10−14 cm2, σp 0(T) ≈ 1 × 10−20 cm2 for EH7. Since EH7 has already been identified as a donor transition of the carbon vacancy, we propose that the EH6∕7 center in total represents the overlapping first and second donor transitions of the carbon vacancy defects on both inequivalent lattice sites.

  • 42.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ul Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Beyer, Franziska
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karhu, Robin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, J. Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Danielsson, Örjan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kordina, Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC2014Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, nr 8, s. 4104-4110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    4H-SiC epilayers grown by standard and chlorinated chemistry were analyzed for their minority carrier lifetime and deep level recombination centers using time-resolved photoluminescence (TRPL) and standard deep level transient spectroscopy (DLTS). Next to the well-known Z(1/2) deep level a second effective lifetime killer, RB1 (activation energy 1.05 eV, electron capture cross section 2 x 10(-16) cm(2), suggested hole capture cross section (5 +/- 2) x 10(-15) cm(2)), is detected in chloride chemistry grown epilayers. Junction-DLTS and bulk recombination simulations are used to confirm the lifetime killing properties of this level. The measured RB1 concentration appears to be a function of the iron-related Fe1 level concentration, which is unintentionally introduced via the corrosion of reactor steel parts by the chlorinated chemistry. Reactor design and the growth zone temperature profile are thought to enable the formation of RB1 in the presence of iron contamination under conditions otherwise optimal for growth of material with very low Z(1/2) concentrations. The RB1 defect is either an intrinsic defect similar to RD1/2 or EH5 or a complex involving iron. Control of these corrosion issues allows the growth of material at a high growth rate and with high minority carrier lifetime based on Z(1/2) as the only bulk recombination center.

  • 43.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yazdanfar, Milan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Shallow boron, the deep D-center and their influence on carrier lifetime in n- and p-type 4H-SiCManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The shallow boron and deep D-center are analyzed by minority carrier transient spectroscopy (MCTS), deep level transient spectroscopy (DLTS) and optical-electrical MCTS in n-type 4H-SiC with varying concentrations of boron, and in p-type 4H-SiC. MCTS, using high resolution correlation functions, shows the D-center to be composed of two closely overlapping peaks, referred to as D(a) and D(b), both most likely originating from the same defect located on inequivalent lattice sites. The hole capture cross sections of the D center are derived from DLTS filling pulse measurements in p-type material. The electron capture behavior of the D-center is analyzed by optical-electrical MCTS, and we find the center to be a pure hole trap, unable to act as a recombination center, with electron capture cross sections smaller than 1·10-23 cm2. The shallow boron peak is found to be composed of two or more overlapping levels in high resolution MCTS spectra. The shallow levels are further demonstrated to produce minority carrier trapping and detrapping effects in n-type 4H-SiC, which result in long time-resolved photoluminescence (TRPL) transients with microsecond decay constants, even in material containing high concentrations of the lifetime killing center Z1/2.

  • 44. Brosselard, P.
    et al.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Pérez-Tomás, A.
    Montserrat, J.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Godignon, P.
    Bipolar Diode on 4H-SiC P+-Substrate2009Inngår i: Materials Science Forum, Vols. 600-603, 2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

        

  • 45. Carlsson, F.H.C.
    et al.
    Wahab, Qamar Ul
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Electroluminescence from 4H-SiC Schottky Diodes2001Inngår i: Mat. Res. Soc. Symp. Proc., Vol. 640, 2001, s. H4.8-Konferansepaper (Fagfellevurdert)
  • 46.
    Carlsson, Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Sridhara, SG
    Hallen, A
    Bergman, JP
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    D-II PL intensity dependence on dose, implantation temperature and implanted species in 4H-and 6H-SiC2003Inngår i: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, s. 345-348Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In most semi-conductor processing ion implantation is a key technology. The drawback of ion implantation is that a great deal of lattice defects, such as vacancies, interstitials, anti sites and complexes, are introduced. The annealing behaviour of these defects is important for the viability of ion implantation as a commonly used method. In SiC a defect that is only seen after ion implantation and not after irradiation with neutrons or electrons is the D-II defect. The use of Si or C as implanted species have made it possible to investigate the D-II photoluminescence (PL) intensity dependence on an excess of either of the two constituents in SiC. The effect of performing a hot implant at 600degreesC compared to a room temperature implant was also looked into. The D-II PL intensity was measured after a 1500degreesC anneal. When the implantation was performed at room temperature the C implanted samples showed a significantly higher D-II luminescence than the Si implanted. This makes it tempting to assume that a surplus of C and likely C interstitials are involved in the defect formation. However, when the implantation is done at 600degreesC the difference between Si and C implanted samples almost disappears and a slightly higher D-II intensity can be seen in the Si implanted samples. This effect may be due to the mobility of C interstitials at temperatures above 500degreesC. This clearly demonstrates the effect of hot implantation that there is a major change in D-II PL intensity even after a 1500degreesC anneal.

  • 47.
    Carlsson, Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Trapped carrier electroluminescence (TraCE) - A novel method for correlating electrical and optical measurements2001Inngår i: Physica B, Vols. 308-310, 2001, Vol. 308-310, s. 1165-1168Konferansepaper (Fagfellevurdert)
    Abstract [en]

    SiC is a semiconductor with very good material properties for high power, high frequency and high temperature applications. During device fabrication irradiation with particles is often used, e.g., ion-implantation, which creates intrinsic defects. The most persistent defect in SiC is DI that appears after irradiation and subsequent high temperature annealing. A direct method called Trapped Carrier Electroluminescence (TraCE) for correlating minority carrier traps with luminescence measurements is presented. A semi-transparent Schottky diode under reverse bias is illuminated with a laser pulse of above band gap light to create minority carriers that are captured to traps in the space charge region. Majority carriers are introduced when the reverse bias is removed and the space charge region is reduced. The majority carriers recombine with the trapped minority carriers and the emitted light from the recombination is detected. TraCE has been used to study and correlate the DI bound exciton luminescence from intrinsic defects in SiC with an electrically observed hole trap HS1. © 2001 Elsevier Science B.V. All rights reserved.

  • 48.
    Carlsson, Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Electroluminescence from implanted and epitaxially grown pn-diodes2000Inngår i: Materials Science Forum, Vols. 338-343, Trans Tech Publications Inc., 2000, Vol. 338-3, s. 687-690Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The electroluminescence from pn-diodes with (1) aluminum doped epitaxially grown, (2) aluminum implanted or (3) aluminum and boron implanted p-layer have been investigated. The temperature dependence for both the spectra and the decays of the major spectral components have been investigated at temperatures from 80 K to 550 K. The implanted diodes show implantation damage in the form of the D-1 center and lack of emission from the aluminum center. The epitaxial diodes show luminescence from the aluminum center. The band edge luminescence is visible above 150 K for the epitaxial diode and above 300 K for the implanted. The emission from deep boron can be seen in the aluminum and boron co-implanted diode and in the epitaxially grown diode that have an unintentional boron doping below 10(17) cm(-3).

  • 49.
    Carlsson, Fredrik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Storasta, Liutauras
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Magnusson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Skold, K
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Uppsala Univ, Inst Neutron Res, SE-61182 Nykoping, Sweden.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Neutron irradiation of 4H SiC2001Inngår i: Materials Science Forum, Vols. 353-356, 2001, Vol. 353-3, s. 555-558Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The effect of neutron irradiation on 4H SiC epitaxial layers are studied. Several different doses of both fast and thermal neutrons have been used and the samples have been annealed from 500 degreesC to 2000 degreesC. The defect concentration dependence on the fast neutron flux and on the annealing temperature is investigated. At temperatures from 900 degreesC to 1300 degreesC new lines between 3960 Angstrom and 4270 Angstrom appear. They are similar in behavior to the E-A and D1 spectra and are assumed to be related to excitons bound to isoelectronic centers. After annealing at 2000 degreesC another new line appears at 3809 Angstrom. The similarity of this line with phosphorus in 6H makes us tentatively ascribe it to phosphorus.

  • 50.
    Carlsson, Patrick
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Nguyen, Son Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Isoya, J.
    Graduate School of Library, Information and Media Studies, University of Tsukuba, 1-2 Kasuga, Tsukuba, Ibaraki 305-8550, Japan.
    Morishita, N.
    Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
    Ohshima, T.
    Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Silicon antisite related defects in electron-irradiated p-type 4H- and 6H-SiCManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The electron paramagnetic resonance (EPR) LE5 centers were previously observed in electron-irradiated p-type 4H- and 6H-SiC but have not been identified due to lack of experimental data. In this study, two different Si hyperfine (hf) structures of the LE5 centers have been detected and the corresponding hf tensors have been determined. One structure is due to a very anisotropic hf interaction with one Si atom and the other structure to the hf interaction with two neighboring Si atoms in the basal plane. The obtained g values and Si hf constants are in good agreement with calculated parameters reported for antisite pairs in 4H-SiC. Based on the similarity in the spin-Hamiltonian parameters, the LE5 centers may be the antisite pairs in the positive charge state.

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