| 1. |
- Sun, J. W., et al.
(författare)
-
Combined effects of Ga, N, and Al codoping in solution grown 3C-€“SiC
- 2010
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 108:1, s. 013503-1-013503-10
-
Tidskriftsartikel (refereegranskat)abstract
- We report on Ga-doped 3C–SiC epitaxial layers grown on on-axis (0001) 6H–SiC substrates using the vapor-liquid-solid technique and different melts. The resulting samples have been investigated using secondary ion mass spectroscopy(SIMS), micro-Raman spectroscopy and, finally, low temperature photoluminescence (LTPL) spectroscopy. From SIMS measurements we find Ga concentrations in the range of , systematically accompanied by high nitrogen content. In good agreement with these findings, the spectra show that the Ga-doped samples are -type, with electron concentrations close to . As expected, the LTPL spectra are dominated by strong N–Ga donor-acceptor pair (DAP) transitions. In one sample, a weak additional N–Al DAP recombination spectrum is also observed, showing the possibility to have accidental codoping with Ga and Al simultaneously. This was confirmed on a non-intentionally doped 3C–SiC (witness) sample on which, apart of the usual N and Al bound exciton lines, a small feature resolved at 2.35 eV comings from neutral Ga bound excitons. Quantitative analyses of the DAP transition energies in the Ga-doped and witness sample gave 346 meV for the optical binding energy of Ga acceptors in 3C–SiC against 251 meV for the Al one. The conditions for the relative observa-tion of Ga and Al related LTPL features are discussed and the demonstration of room temperature luminescence using Ga doping is done.
|
|
| 2. |
- Sun, J. W., et al.
(författare)
-
Splitting of close N-€Al donor-€acceptor-€pair spectra in 3C-€SiC
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Discrete series of lines have been observed for many years in N‐Al DAP (Donor Acceptor Pair) spectra in 3C‐SiC. Unfortunately, up to now, there has been no quantitative analysis for the splitting of lines in a given shell. This is done in this work for N‐Al DAP spectra in 3C‐SiC. The samples were non‐intentionally doped 3C‐SiC layers grown by CVD on a VLS seeding layer grown on a 6H‐SiC substrate. From low temperature photoluminescence measurements, strong N‐Al DAP emission bands were observed and, on the high energy side of the zero‐phonon line, we could resolve a series of discrete lines coming from close pairs. Comparing with literature data, we show that the splitting energy for a given shell is constant and, to explain this shell substructure, we consider the non equivalent sets of sites for a given shell. Results are discussed in terms of the ion‐ion interaction containing third and forth multipole terms.
|
|
| 3. |
- Zoulis, G., et al.
(författare)
-
Effects of Growth Conditions on the Low Temperature Photoluminescence Spectra of (111) 3C-€SiC Layers Grown by Chemical Vapor Deposition on 3C-€SiC Seeds grown by the Vapor-€Liquid-Solid Technique
- 2010
-
Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X.
-
Konferensbidrag (refereegranskat)abstract
- We report the results of a low temperature photoluminescence investigation of 3C‐SiC samples grown by chemical vapor deposition on vapor‐liquid‐solid seeds. The main parameters tested in this series of samples were i°) the effects of changing the C/Si ratio and ii°) the growth temperature on the final growth product. On the first series the C/Si ratio varied from 1 to 14 for a constant growth temperature of 1550° C. For the second series, the growth temperature varied from 1450 to 1650° C by steps of 50° C with a constant C/Si ratio equal to 3. According to this work, the best results (minimum incorporation of impurities and best crystal quality) were obtained when using a C/Si ratio of 3 at 1650° C.
|
|
