Tunable Schottky barrier of WSi2N4/graphene heterostructure via interface distance and external electric field

Abstract

Improving the electric transport of field-effect transistors based on heterostructure (HTS) is a stern challenge by the reduction of the interfacial barrier. Herein, the electronic properties of WSi2N4/graphene HTS with different interface distance or external electric field are researched in detail using the first-principles approach. The result shows that a stable vdW HTS can be produced between WSi2N4 and graphene. In the interface, the tunable range of Schottky barrier height by external electric field exceeds that by interface distance, although both of two prominent approaches can modulate the energy band structures of WSi2N4/graphene HTSs. The transformation of Schottky contact from p-type to n-type, eventually into Ohmic contact can appear under external electric field. Predictably, the positive external electric field strength of 0.55 V·Å−1 can generate the largest carrier concentration 2.73 × 1013 cm−2 of graphene in the HTS. Verifiably, the redistribution of interface charge density determines the Schottky barrier height and contact type in the HTS. These findings present the potential of WSi2N4/graphene HTS as high sensitive Schottky field-effect transistors.