Alloy Disorder Effects In Molecular Beam Epitaxically Grown AlxGa1-xAs Examined Via Raman And Rayleigh Scattering And Near Edge Luminescence

Raman scattering, Rayleigh scattering and band edge photoluminescence are employed to examine the behavior of alloy disorder in AlxGa1-xAs alloys grown on GaAs(100) under reflection high energy electron diffraction determined growth conditions in molecular beam epitaxy. Evidence is found for the dependence of the short and long range disorder effects on the growth kinetics attendant to chosen growth conditions and on the Al concentration. At high Al concentration (xAl~0.8) evidence is found for the occurrence of atomic scale GaAs-like and AlAs-like regions. In addition, the "AlAs-like" TO mode is observed in the forbidden back scattering geometry and is likely due to strain and/or disorder related breakdown of the usual selection rules.