Study of band offsets in CdF2/CaF2/Si(111) heterostructures using x-ray photoelectron spectroscopy

The valence band offsets at the heterointerfaces of the CdF2/CaF2/Si(111) structure grown by molecular beam epitaxy were evaluated using x-ray photoelectron spectroscopy, and the energy band diagram of this heterostructure was proposed. It was found that the interface of CdF2/CaF2 has large conduction band offset: 2.9 eV, and the energy level of CdF2 conduction band edge is below that of Si.