| 1. |
- ul Hassan, Jawad, et al.
(författare)
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On-axis homoepitaxial growth of 4H-SiC PiN structure for high power applications
- 2013
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Ingår i: Silicon Carbide and Related Materials 2012. - : Trans Tech Publications Inc.. - 9783037856246 ; 740-742, s. 173-176, s. 173-176
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Konferensbidrag (refereegranskat)abstract
- We demonstrate on-axis homoepitaxial growth of 4H-SiC(0001) PiN structure on 3-inch wafers with 100% 4H polytype in the epilayer excluding the edges. The layers were grown with a thickness of 105 μm and controlled n-type doping of 4 x 1014 cm-3.The epilayers were completely free of basal plane dislocations, in-grown stacking faults and other epitaxial defects, as required for 10 kV high power bipolar devices. Some part of the wafer had a lifetime enhancement procedure to increase lifetime to above 2 μs using carbon implantation. An additional step of epilayer polishing was adapted to reduce surface roughness and implantation damage.
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| 2. |
- Danielson, E., et al.
(författare)
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Investigation of thermal properties in fabricated 4H-SiC high power bipolar transistors
- 2003
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Ingår i: Solid-State Electronics. - 0038-1101 .- 1879-2405. ; 47:4, s. 639-644
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Tidskriftsartikel (refereegranskat)abstract
- Silicon carbide bipolar junction transistors have been fabricated and investigated. The transistors had a maximum current gain of approximately 10 times, and a breakdown voltage of 450 V. When operated at high power densities the device showed a clear self-heating effect, decreasing the current gain. The junction temperature was extracted during self-heating to approximately 150 degreesC, using the assumption that the current gain only depends on temperature. Thermal images of a device under operation were also recorded using an infrared camera, showing a significant temperature increase in the vicinity of the device. The device was also tested in a switched setup, showing fast turn on and turn off at 1 MHz and 300 V supply voltage. Device simulations have been used to analyze the measured data. The thermal conductivity is fitted against the self-heating, and the lifetime in the base is fitted against the measurement of the current gain.
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| 3. |
- Forsberg, Urban, 1971-, et al.
(författare)
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Nitrogen doping of epitaxial Silicon Carbide
- 2002
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Ingår i: Journal of Crystal Growth. - : ScienceDirect. - 0022-0248 .- 1873-5002. ; 236:1-3, s. 101-112
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Tidskriftsartikel (refereegranskat)abstract
- Intentional doping with nitrogen of 4H- and 6H-SiC has been performed using a hot-wall CVD reactor. The nitrogen doping dependence on the temperature, pressure, C/Si ratio, growth rate and nitrogen flow has been investigated. The nitrogen incorporation for C-face material showed to be C/Si ratio independent, whereas the doping decreased with increasing C/Si ratio for the Si-face material in accordance with the “site-competition” model. The nitrogen incorporation was constant in a temperature “window” of 75°C on Si-face material indicating a mass transport limited incorporation. Increasing the growth rate resulted in a decrease of nitrogen incorporation on Si-face but an increase on C-face material. Finally, a comparison between previously published results on cold-wall CVD-grown material and the present hot-wall-grown material is presented.
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| 4. |
- Forsberg, Urban, et al.
(författare)
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Photoluminescence study of CVD layers highly doped with nitrogen
- 2000
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Ingår i: Materials Science Forum, Vols. 338-342. - 0878498540 ; , s. 619-622, s. 619-622
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Konferensbidrag (refereegranskat)abstract
- From a systematic study of highly doped n-type 4H-SiC epilayers we observe a photoluminescence spectrum, which was previously associated with the recombination of a bound exciton at the neutral boron acceptor. Electrical measurements performed on these layers show clearly n-type conductivity. It was feasible to dope and measure reproducibly the layers from low 10(17) to mid 10(18) cm(-3). It was not possible to determine the doping from Capacitance Voltage measurements for the samples grown with the highest doping (>6.10(18) cm(-3)). However Secondary Ion Mass spectrometry did not reveal any boron impurities in the layers and shows good agreement with electrical measurements regarding the nitrogen concentration.
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| 5. |
- Hemmingsson, Carl, 1964-, et al.
(författare)
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Deep-Level Defects in Electron-irradiated 4H SiC Epitaxial Layers
- 1997
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 81:9, s. 6155-6159
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Tidskriftsartikel (refereegranskat)abstract
- Deep level defects in electron-irradiated 4H SiC epitaxial layers grown by chemical vapor deposition were studied using deep level transient spectroscopy. The measurements performed on electron-irradiated p+n junctions in the temperature range 100–750 K revealed several electron traps and one hole trap with thermal ionization energies ranging from 0.35 to 1.65 eV. Most of these defects were already observed at a dose of irradiation as low as ≈5×1013 cm-2. Dose dependence and annealing behavior of the defects were investigated. For two of these electron traps, the electron capture cross section was measured. From the temperature dependence studies, the capture cross section of these two defects are shown to be temperature independent. © 1997 American Institute of Physics.
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| 6. |
- Henry, Anne, et al.
(författare)
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Determination of nitrogen doping concentration in doped 4H-SiC epilayers by low temperature photoluminescence
- 2005
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; 72:2-3, s. 254-257
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Tidskriftsartikel (refereegranskat)abstract
- A complete calibration of nitrogen concentration in doped 4H-SiC material is presented. This is done in the very large range of doping available today, i.e. from low 1014 to 1019 cm-3. The samples are 4H-SiC films fabricated by hot-wall chemical vapour deposition. Low temperature photoluminescence is used as the experimental tool. For doping concentrations less than 8 × 1017 cm-3 comparison between the intensity of various luminescence lines is used, whereas for doping higher than 3 × 1018 cm-3 the energy position of an observed broad band allows the determination of the doping level.
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| 7. |
- Henry, Anne, et al.
(författare)
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Presence of hydrogen in SiC
- 2001
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Ingår i: Materials Science Forum, Vols. 353-356. ; , s. 373-376, s. 373-376
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Konferensbidrag (refereegranskat)abstract
- An unexpected presence of hydrogen in 4H-SiC was revealed by the observation of hydrogen related lines in the low-temperature photoluminescence (LTPL) spectrum after secondary ion mass spectrometry (SIMS) measurements. The lines were not observed before SIMS. The high-energy ions during SIMS are proposed to break the boron-hydrogen bonds. This phenomenon is observable only for a certain impurity concentration in the material due to the competition of various recombination channels during the LTPL experiment.
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| 8. |
- Ivanov, Ivan Gueorguiev, 1955-, et al.
(författare)
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Wave-function symmetry and the properties of shallow P donors in 4H SiC
- 2009
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Ingår i: Silicon Carbide and Related Materials 2007, Pts 1 and 2. - : Trans Tech Publications Inc.. ; , s. 445-448, s. 445-448
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Konferensbidrag (refereegranskat)abstract
- A new investigation on the optical properties of the phosphorus-bound excitons is presented. Arguments are given in favor of the possibility of degenerate donor state for phosphorus substituting Si atom on hexagonal site. On the base of a simple model, it is shown that the experimental spectra also provide evidence in favor of this possibility. The possibility for violation of the Haynes rule in the case of phosphorus donors on the two inequivalent sites is indicated.
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| 9. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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Cathodoluminescence identification of donor-acceptor related emissions in as-grown 4H-SiC layers
- 2002
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:5, s. 2890-2895
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Tidskriftsartikel (refereegranskat)abstract
- A comparative analysis of cathodoluminescence spectra in 4H-SiC layers with different N, Al, and B content is reported. The layers were produced by sublimation epitaxy and residual impurity concentrations were determined by secondary ion mass spectrometry. Epilayers doped with B in a wide concentration range, 5x10(15)-3x10(18) cm(-3), were achieved. Evidence of N, Al, and B related emissions by cathodoluminescence experiments is presented. Differences in the luminescence emitted by the layers are established that are attributed to different B content and impurity cooperation. The characteristics of broad green emission, originating from B-related centers, at 4.6 K, 300 K, as well as in high temperature annealed layers are discussed. The experimental results suggest that boron is involved in more than one deep acceptor center.
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| 10. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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Kinetics of residual doping in 4H-SiC epitaxial layers grown in vacuum
- 2002
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 240:04-mar, s. 501-507
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Tidskriftsartikel (refereegranskat)abstract
- Investigation on residual Al, B, and N co-doping of 4H-SiC epitaxial layers is reported. The layers were produced by sublimation epitaxy in Ta growth cell environment at different growth temperatures and characterized by secondary ion mass spectrometry. The vapor interaction with Ta was considered through calculations of cohesive energies of several Si-, Al-, B-, and N-containing vapor molecules and also of diatomic Ta-X molecules. An analysis of kinetic mechanisms responsible for impurity incorporation is performed. Among residuals, B exhibits a stronger incorporation dependence on temperature and growth at lower temperatures can favor B decrease in the layers. Under the growth conditions in this study (Ta environment and presence of attendant Al and N), B incorporation is assisted by Si2C vapor molecule. Boron tends to occupy carbon sites at higher temperatures, i.e. higher growth rates.
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