Incorporation of Silicon and Aluminum in Low-Temperature Molecular-Beam Epitaxial GaAs

The localized vibrational modes (LVMs) of silicon donor (SiGa) and aluminum isovalent (AlGa) impurities in molecular beam epitaxial GaAs layers grown at various temperatures are studied using the infrared absorption technique. It is found that the total integrated absorption of these impurities LVMs is decreased as the growth temperature decreases. This finding suggests a nonsubstitutional incorporation of Si and Al in GaAs layers grown at 200 °C. On the other hand, a subtitutional incorporation is obtained in GaAs layers grown at temperatures higher than 350 °C. A recovery of the SiGa LVMs in GaAs layers grown at 200 °C has not been achieved by thermal annealing