Dynamics of the H-CAscomplex in GaAs determined from Raman measurements

Di-Carbon Defects in Annealed Highly Carbon Doped GaAs

“…The polarization of the incident light was either parallel or perpendicular to that of the detected light. The thicknesses of the epitaxial layers ͑.300 nm͒ were much greater than the probing depths in the Raman experiments of 20 and 10 nm, respectively for the two lasers [12]. Raman measurements (2.71 eV excitation) made on a sample with ͓ 12 C As ͔ 0 (Raman and SIMS) ϳp 0 ϳ 2.5 3 10 20 cm 23 (Hall) showed reductions in the strength of the scattering from the 13 C As mode upon thermal annealing, corresponding to a ϳ70% reduction in ͓ 13 C As ͔ using the established calibration for 12 C As [13].…”

“…In annealed (825 ± C, 3.5 h) GaAs: 12 12 C to 13 C. The triplet structures shown by sample (c) demonstrate that the defects are bonded (C-C) dicarbon defects ( Table I). have full widths at half height D 8 cm 21 and those at the higher frequencies (T2) have D 17 cm 21 . The modes have A 1 symmetry since the strength of the scattering is greater for parallel rather than crossed polarizations of the incident and scattered radiation [12]. We note that the frequency of the line from 12 C-12 C pairs at 1742 cm 21 is comparable with that of a double bonded C--C structure that has a characteristic frequency of 1650 cm 21 in molecules [14].…”

“…19 cm 23 were present as electrically neutral complexes. Weak Raman scattering from the symmetric A 1 mode of H-C As pairs was present in some as-grown samples [12], although it was usually, but not always, absent after the anneal ͓͑H-C As ͔ # 3 3 10 18 cm 23 ; detection limit #5 3 10 17 cm 23 ; measurements made on 4 samples͒. The loss of C As was therefore not due predominantly to the indiffusion of H atoms during the cooling period at the end of the anneal.…”

“…The samples were grown at 540 ± C by CBE using triethylgallium and cracked arsine and were doped with carbon ( 12 C, 13 [3,12]). Anneals, carried out in flowing gas (10% H 2 in Ar) with a faceto-face capping configuration using undoped GaAs, were made at temperatures up to 850 ± C for up to 4 h. Raman measurements (77 K) were made in the backscattering geometry using excitation either from an Ar 1 ion laser ͑hn L 2.71 eV͒ or from a Kr 1 ion laser (hn L 3.00 74 0031-9007͞ 96͞78(1)͞74(4)$10.00 © 1996 The American Physical Society VOLUME 78, NUMBER 1…”

“…or 3.05 eV) [12]. The polarization of the incident light was either parallel or perpendicular to that of the detected light.…”