Low density of states at the epitaxial CaF₂-Si(111) interface

The density of interface states at the epitaxial CaF2-Si(111) interface grown under UHV conditions at 700 °C is found to be much lower than assumed previously, as revealed from photoelectron spectroscopy. An upper limit is estimated to be 3 × 1012 cm-2 eV-1 near midgap, which comes close to values obtained for SiO2-Si interfaces.