Structure and Bonding at the CaF2/GaAs(111) Interface

Abstract

Surface sensitive core level spectroscopy with synchrotron radiation (SRPES) is performed to determine bonding properties at the CaF₂/GaAs(111) interface. The layer-by-layer growth of CaF₂ was found. CaF₂ interfacial states were clearly distinguished from CaF₂ bulk states using chemical shifts of Ca3p and F2s core levels. Although the stoichiometry of CaF₂ in the first layer differs from that of CaF₂ bulk, the interface is abrupt, implying the possibility of MIS devices with good quality. A structural model with an abrupt interface and layer-grown CaF₂ film is proposed based on these SRPES results.