Density functional theory study on the two-dimensional interfacial conducting states at the Zincblende-Si semiconductor superlattices

Abstract

Since the discovery of the two-dimensional (2D) interfacial conducting states in oxide-based materials such as SrTiO3-based heterointerfaces, there have been considerable interests in 2D metallic systems at the interfaces due to their potential for device applications arising from high mobility properties in several 2D conducting phases of the interfaces. These 2D interfacial conductive states are not limited to oxide-based materials but 2D interfacial conducting states have also been known to exist in a group of zincblende semiconductor superlattices. In this study, we conduct extensive density functional theory calculations to investigate the interfacial characteristics of heterostructures which are composed of III-V (II-VI) zincblende semiconductors and Si. Our results show that the formation of the 2D interfacial conducting states strongly depends on the crystal growth direction and thickness of zincblende and Si. Moreover, our charge transfer calculations demonstrate that the atomic compositions and the difference in electronegativity at the interfaces are important factors in the appearance of the 2D metallic states. To evaluate the mobility of the charge carriers for potential future device applications, we compute the electron/hole effective mass (m*) of the present 2D metallic phases. Consequently, we find that zincblende-Si interface superlattices have the small effective mass of electron/hole, which is one of the crucial requirements for the high mobility devices.