Formation of the ZnSe/(Te/)GaAs(1 0 0) heterojunction

We have investigated the underlying electronic and structural effects of the previously published influence of a Te substrate pretreatment on the heterovalent ZnSe/GaAs(1 0 0) interface [Appl. Phys. Lett. 78 (2001) 1867]. For this purpose, photoelectron spectroscopy and density functional theory calculations were employed. To determine the valence band maximum accurately, the choice of suitable photon energies to maximize the contribution from the Γ-point as well as a variation of the k-vector by measuring under selected angles is investigated. We discuss the resulting band offsets with respect to the atomic interface structure and to the broadening of core level line shapes. The theoretical investigations focus on the effect of replacing Se by Te atoms at the interface, particularly in view of the lattice structure and the band offsets. We find that Te helps to establish a group-VI-rich interface, thus lowering the valence band offset, while maintaining a good crystal quality by acting as a diffusion barrier for Se atoms.