Effects of substrate misorientation on incorporation of ambient oxygen and interfacial roughness in AlGaAs/GaAs heterostructures grown by molecular-beam epitaxy

Abstract

By secondary ion-mass spectrometry (SIMS) and transmission-electron microscopy (TEM), we have studied the effects of substrate misorientation and GaAs monolayers on the incorporation of ambient oxygen and interfacial roughness in AlxGa1−xAs/GaAs heterostructures grown by molecular-beam epitaxy. Consistent with earlier works, O is found in AlGaAs only, and not in GaAs. Incorporation of O, and surface and interfacial roughness are reduced if the substrate is misoriented towards 〈111〉A. The O atoms in AlGaAs are mobile enough to segregate on the surface and remain trapped at the GaAs/AlGaAs inverted interfaces, even when the GaAs layer is as thin as one monolayer.