Effect of a ZnSe intralayer on the Si/Ge(111) heterojunction band offsets

Soft X-ray photoelectron spectroscopy (SXPS) was performed on Si/Ge(111)-c(2 × 8) heterojunctions. The effect of an ordered ultrathin (one monolayer) ionic dipole layer of ZnSe placed at the interface was studied. The formation of the interface was monitored via the evolution of the valence band edges and the movements of core levels. It was found that the ZnSe intralayer dramatically modified the valence band offset of the Si/Ge (111) junction. The valence band offset was increased by 0.57 ± 0.1 eV due to the presence of the ZnSe intralayer. This intralayer-induced modification of the valence band offset is interpreted in terms of the charge transfer at the interface.