| 1. |
- Gällström, Andreas, 1978-, et al.
(författare)
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The Electronic Structure of the UD-4 defect in 4H, 6H and 15R SiC
- 2009
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Ingår i: Materials Science Forum, Vols. 600-603. - : Trans Tech Publications. ; , s. 397-400
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Konferensbidrag (refereegranskat)abstract
- The photoluminescence (PL) of the UD-4 defect is observed in semi-insulating bulk 4H, 6H and 15R SiC. In 4H and 6H SiC the UD-4 defect consists of two families of no-phonon (NP) lines, Ua and Ub, and in 15R SiC it consists of three families, Ua, Ub and U15R. The Ua family in 4H, 6H and 15R all show similar temperature behavior with higher energy NP lines becomming observable at higher temperatures. In the case of the Ub and U15R families, a luminescence line with lower energy than the prominent luminescence line appears at higher temperatures. The polarization and Zeeman measurements suggest that the defect has C3v symmetry.
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| 2. |
- Henry, Anne, 1959-, et al.
(författare)
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Thick epilayers for power devices
- 2007
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Ingår i: Materials Science Forum, vol. 556-557. - : Trans Tech Publications. ; , s. 47-
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Konferensbidrag (refereegranskat)abstract
- Growth of thick epitaxial SiC layers needed for high power devices is presented for horizontal hot-wall CVD (HWCVD) reactors. We demonstrate thickness of epilayer of 100 μm and more with good morphology, low-doping with no doping variation through the whole thick layer and reasonable carrier lifetime which mainly depends on the substrate quality. Typical epidefects are described and their density can dramatically be reduced when choosing correctly the growth conditions as well as the polishing of the surface prior to the growth. The control of the doping and thickness uniformities as well as the run-to-run reproducibility is also presented. Various characterization techniques such as optical microscopy, AFM, reflectance, CV, PL and minority carrier lifetime have been used. Results of high-voltage SiC Schottky power devices are presented.
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| 3. |
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| 4. |
- Bergman, Peder, 1961-, et al.
(författare)
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Improved SiC Epitaxial Material for Bipolar Applications
- 2008
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Ingår i: Proc. of MRS Spring Meeting 2008. ; , s. D05-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 5. |
- Beyer, Franziska, 1980-, et al.
(författare)
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Defects in 4H-SiC Layers Grown by Chloride-based Epitaxy
- 2009
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Ingår i: Materials Science Forum Vols. 615-617. - : Trans Tech Publications. ; , s. 373-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Engelbrecht, J. A. A., et al.
(författare)
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Comparison of experimental results with theoretical models for the temperature dependence of the band gap of AlxGa1-xN epilayers
- 2022
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Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 33, s. 22492-22498
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Tidskriftsartikel (refereegranskat)abstract
- The band gap energies AlxGa1-xN epilayers prepared on two different substrates were assessed using Fourier Transform Infrared (FTIR) reflectance spectroscopy, photoluminescence (PL) and scanning electron microscopy electron dispersive spectroscopy (SEM-EDS). The results were compared to various theoretical formulae to calculate the band gap, and deviations elucidated.
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| 10. |
- Gällström, Andreas, 1978-, et al.
(författare)
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Influence of Cooling Rate after High Temperature Annealing on Deep Levels in High-Purity Semi-Insulating 4H-SiC
- 2007
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Ingår i: Materials Science Forum, vol. 556-557. - : Trans Tech Publications. ; , s. 371-
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Konferensbidrag (refereegranskat)abstract
- The influence of different cooling rates on deep levels in 4H-SiC after high temperature annealing has been investigated. The samples were heated from room temperature to 2300°C, followed by a 20 minutes anneal at this temperature. Different subsequent cooling sequences down to 1100°C were used. The samples have been investigated using photoluminescence (PL) and IV characteristics. The PL intensities of the silicon vacancy (VSi) and UD-2, were found to increase with a faster cooling rate.
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