Disorder of an AlAs-GaAs superlattice by impurity diffusion

Abstract

Data are presented showing that Zn diffusion into an AlAs-GaAs superlattice (41 Lz∼45-Å GaAs layers, 40 LB∼150-Å AlAs layers), or into AlxGa1-xAs-GaAs quantum-well heterostructures, increases the Al-Ga interdiffusion at the heterointerfaces and creates, even at low temperature (<600°C), uniform compositionally disordered AlxGa1-xAs. For the case of the superlattice, the diffusion-induced disordering causes a change from direct-gap AlAs-GaAs (Eg∼1.61 eV) to indirect-gap AlxGa1-xAs (x∼0.77, EgX∼2.08 eV).