First-principles studies on the interfacial conducting states on the zincblende semiconductor superlattices

Two-dimensional (2D) conducting states on the interface between insulating materials have brought about enormous interests because they show a variety of fascinating physics such as high-mobility and superconductivity. Since the discovery of 2D interfacial conducting states at SrTiO₃-based heterointerfaces, it has been reported that 2D interfacial metallicity is also observed in certain zincblende semiconductor superlattices. To explore wider materials classes, we investigate the interfacial characteristics on the zincblende semiconductor superlattices composed of III-V(AlAs, AlP, GaAs, GaP)/Si, II-VI(ZnS, ZnSe)/Si and III-V/II-VI. Our electronic structure calculations demonstrate that the formation of the interfacial conducting states in zincblende semiconductors is very general and their existence highly depends on the orientation and superlattice period. To clarify the origin of the conducting states, we analyze the charge transfer at each orientation of the interfaces. It is found that the charge transfer is governed by the compositions of the interfacial atoms on each superlattice and that the difference in electronegativity between interfacial atoms plays a crucial role in forming the conducting states.