Structure and properties of CaF2/GaAs (100) heterojunctions

Fluorite (CaF2) is a wide band gap dielectric, nearly lattice matched to GaAs (3.5%), that can be grown epitaxially on GaAs. We have used synchrotron radiation in the 1.6- 60-nm wavelength range and photoelectron spectroscopy to study the electronic properties and structure of the CaF2/GaAs interface as a prototypical example of the broader class of alkaline earth halide/III-IV semiconductor heterojunction. Such heterojunctions are of possible interest in optical and electrooptic devices.