▎ 摘　　要

The ultra-wide-gap beta-Ga2O3 has been regarded as a promising material for next-generation power electronic and deep-ultraviolet (UV) photodetectors. Exploring a suitable electrode is vital for realizing high performance beta Ga2O3 based nanodevices. Herein, the structural and contact properties of graphene/Ga2O3 interfaces are tuned and investigated by using the first-principles calculations. Results show that the small n-type Schottky barrier of about 0.07 eV for the graphene/Ga2O3 interface with weak interlayer interaction is irrespective of the interface stacking arrangement. Moreover, the intrinsic electronic property of Ga2O3 is well preserved in the interface. More interestingly, the n-type Schottky barrier to Ohmic contact transition can be obtained by shorting the interlayer distance, or increasing the graphene layers or applying a negative external electric field for the interface. Moreover, applying a large positive external electric field can realize the p-type Schottky barrier to Ohmic contact transition for graphene/Ga2O3 interface. These results are uncovered by analyzing the interfacial dipole and potential step of graphene/Ga2O3 interface, and expected to enhance the application potential of graphene electrode in the beta-Ga2O3 based electronic and optoelectronic devices.