Interfacial chemical bonding state and band alignment of CaF2/hydrogen-terminated diamond heterojunction

CaF2 films are deposited on hydrogen-terminated diamond (H-diamond) by a radio-frequency sputter-deposition technique at room temperature. Interfacial chemical bonding state and band alignment of CaF2/H-diamond heterojunction are investigated by X-ray photoelectron spectroscopy. It is confirmed that there are only C-Ca bonds at the CaF2/H-diamond heterointerface. Valence and conductance band offsets of the CaF2/H-diamond heterojunciton are determined to be 3.7 ± 0.2 and 0.3 ± 0.2 eV, respectively. It shows a type I straddling band configuration. The large valence band offset suggests advantage of the CaF2/H-diamond heterojunciton for the development of high power and high frequency field effect transistors.