A density functional study of the effect of hydrogen on electronic properties and band discontinuity at anatase TiO₂/diamond interface

Tailoring the electronic states of the dielectric oxide/diamond interface is critical to the development of next generation semiconductor devices like high-power high-frequency field-effect transistors. In this work, we investigate the electronic states of the TiO₂/diamond 2 × 1–(100) interface by using first principles total energy calculations. Based on the calculation of the chemical potentials for the TiO₂/diamond interface, it is observed that the hetero-interfaces with the C-OTi configuration or with two O vacancies are the most energetically favorable structures under the O-rich condition and under Ti-rich condition, respectively. The band structure and density of states of both TiO₂/diamond and TiO₂/H-diamond hetero-structures are calculated. It is revealed that there are considerable interface states at the interface of the anatase TiO₂/diamond hetero-structure. By introducing H on the diamond surface, the interface states are significantly suppressed. A type-II alignment band structure is disclosed at the interface of the TiO₂/diamond hetero-structure. The valence band offset increases from 0.6 to 1.7 eV when H is introduced at the TiO₂/diamond interface.