Epitaxial CaF2/BaF2-on-Si layers and electronic properties of the interface with the substrate

Layers of CaF
₂
and BaF
₂
were grown on Si substrates using molecular beam epitaxy. X-ray photoelectron spectroscopy has shown that the interface in Si-BaF
₂
structure at 750°C is mainly formed with Si-Ba bonds. Metal-insulator structures have been formed, and capacitance-voltage characteristics (C-V and G-V characteristics) were measured at various test voltage frequencies. Despite of the high density of broken bonds at the interface (about 10
¹⁴
cm
^-2
), the density of electronic states calculated from C-V and G-V characteristics was about 10
¹¹
eV
^-1
cm
^-2
.