Annealing of As{sub Ga}-related defects in LT-GaAs: The role of gallium vacancies
- Lawrence Berkeley Lab., CA (United States)
- Univ. of California, Berkeley, CA (United States)
We have studied the annealing properties of As{sub Ga}-related defects in layers of GaAs grown at low substrate temperatures (300{degrees}C) by molecular beam epitaxy (low temperature[LT]-GaAs). The concentration of neutral As{sub Ga}-related native defects, estimated by infrared absorption measurements, ranges from 2 x 10{sup 19} to 1 x 10{sup 20} cm{sup -1}. Slow positron annihilation results indicate an excess concentration of Ga vacancies in LT layers over bulk grown crystals. A sharp annealing stage at 450{degrees}C marks a rapid decrease in the As{sub Ga} defect concentration. We propose that the defect removal mechanism is the diffusion of As{sub Ga} to arsenic precipitates, which is enhanced by the presence of excess V{sub Ga}. The supersaturated concentration of V{sub Ga} must also decrease. Hence, the diffusivity of the As{sub Ga} defects is time dependent. Analysis of isothermal annealing kinetics gives an enthalpy of migration of 2.0 {+-} 0.3 eV for the photoquenchable As{sub Ga} defects, 1.5 {+-} 0.3 eV for the V{sub Ga}, and 1.1 {+-} 0. 3 eV for the nonphotoquenchable defects. The difference in activation enthalpy represents difference energy between an As atom and Ga atom swapping sites with a V{sub Ga}. 13 refs., 3 figs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 535210
- Journal Information:
- Journal of Electronic Materials, Journal Name: Journal of Electronic Materials Journal Issue: 12 Vol. 22; ISSN JECMA5; ISSN 0361-5235
- Country of Publication:
- United States
- Language:
- English
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