The effect of arsenic pressure on the diffusion-induced disordering of tin in AlAs-GaAs superlattices

Abstract

Tin diffusions into AlAs-GaAs superlattices have been performed in sealed silica ampoules. The present experiments, for the first time, examine the effect of As on tin induced disordering. SIMS and shallow-angle bevel revealed that both the tin surface concentration and the width of the disordered region are increased when a higher arsenic pressure inside the ampoule is used. Such dependence on the arsenic pressure is explained by the diffusion via a negatively charged complex which may take the form of [VGaSnAsVGa]−. The disordering effect could be attributed to the diffusion of Ga vacancies associated with the migration of the complexes. However, a more likely explanation is the Fermi-Level effect which has been proposed to explain the enhancement of the interdiffusion in Si doped samples.