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

Kongping Wu,Yasuo Koide,Liwen Sang,Jiangwei Liu,Meiyong Liao,Masataka Imura,Haitao Ye

doi:10.1063/1.5002176

Abstract

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.

Highlights

The device performance of diamond MOSFETs strongly depends on the gate dielectric materials and oxide/diamond interfaces
In this work, we investigate the electronic states of the TiO2/diamond 2 Â 1–(100) interface by using first principles total energy calculations
We note that the simulation is not the realistic amorphous TiOx on diamond, the findings could be a guideline for the fabrication of diamond electronic devices

Summary

Introduction

The device performance of diamond MOSFETs strongly depends on the gate dielectric materials and oxide/diamond interfaces. Various oxides such as Al2O3, HfO2, and ZrO2 were utilized as the gate dielectric for H-diamond MOSFETs.[9–13]. Titanium oxide (TiO2) was reported by our group as the gate dielectric on H-diamond, resulting in normally off MOSFETs when using a low-temperature oxidation method.[14]. We perform first-principles calculations on the effect of hydrogen on the electronic properties and band alignments of the anatase TiO2/H-diamond interface. It is disclosed that the anatase TiO2/diamond interface exhibits a staggered (type II) band alignment. The introduction of hydrogen leads to an increase in the valence band offset from 0.6 to 1.7 eV at the anatase TiO2/H-diamond interface

Methods

Results

Conclusion