Change of electrical and structural properties of non-stoichiometric GaAs through Be doping

Abstract

he effect of Be doping on the electrical and structural properties of low temperature MBE grown GaAs (LT-GaAs) is investigated for high Be doping levels. As in undoped LT-GaAs As precipitates form upon annealing. However, from the Ostwald ripening of As precipitates a considerably larger activation energy for As diffusion is found in Be doped samples. Therefore, Be doping retards the growth of As precipitates and leads to a thermal stabilization. The electrical properties of as-grown and annealed samples can be explained by the residual point defect model. After short annealing times highly resistive material is obtained, i.e. the Fermi level is pinned at the deep As/sub Ga/ donor midgap states.