Deep-Level Impurities: A Possible Guide to Prediction of Band-Edge Discontinuities in Semiconductor Heterojunctions

Abstract

Since transition-metal impurity levels are found to be aligned with respect to each other within a group of isovalent semiconductor compounds, as if a common reference level existed for them, we propose to use this fictitious level for the band alignment in semiconductor heterojunctions. This rule leads to a valence-band discontinuity in ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}/\mathrm{GaAs}$ heterojunction of $\Delta E_v=(0.34\mathrm{}\pm 0.05)x\Delta E_g$ (AlAs/GaAs) in agreement with the most recent measurements. Predictions of several III-V on III-V and II-VI on II-VI heterojunction band-edge discontinuities are also given.