Measurement of ZnSe–GaAs(110) and ZnSe–Ge(110) heterojunction band discontinuities by x-ray photoelectron spectroscopy (XPS)

Abstract

X‐ray photoelectron spectroscopy was used to study the growth and energy‐band alignment of ZnSe–GaAs(110) and ZnSe–Ge(110) heterojunctions. The ZnSe–GaAs heterojunctions were formed by growing ZnSe on GaAs(110). Growth temperatures were varied to produce both epitaxial and nonepitaxial interfaces. For ZnSe grown at ∠300 °C on GaAs(110), the valence‐ band discontinuity ΔE v was 0.96 eV; for ZnSe deposited at room temperature and crystallized at ∠300 °C, ΔE v is 1.10 eV. The Ge–ZnSe(110) interfaces were formed by depositing Ge(ZnSe) on ZnSe(Ge)(110) at room temperature, followed by ∠300 °C crystallization. The corresponding ΔE v’s were 1.52 and 1.29 eV, respectively. Our measured ΔE v values for epitaxialheterojunctions are compared with the predictions of theoretical models. Our results demonstrate that substantial interface structure dependent contributions to ΔE v can occur at Ge–ZnSe(110) and GaAs– ZnSe(110) heterojunctions.