▎ 摘　　要

The combination of graphene (GR) and monolayer MoSi2N4 has attracted much attention; however, the comprehension of its electrical contact modulation is still not fully explored. Herein, the influence of the interlayer spacing and external electric field on the interfacial characteristic and electronic structure of the GR/MoSi2N4 heterojunction was systematically investigated using first-principles calculations. It is found that a stable van der Waals heterojunction forms when GR incorporates on the MoSi2N4 sheets. The results indicate that both the type and height of the Schottky barrier could be tuned by altering the interlayer spacing between GR and MoSi2N4 sheets or applying a vertical external electric field on the GR/MoSi2N4 heterojunction. Noteworthily, the Schottky barrier height markedly changes about 0.2-0.3 eV with the increase of external electric field per 0.1 V.A(-1). It is confirmed that the change of energy bands is caused by the charge redistribution with the interlayer spacing and external electric field. These findings will provide rational evidence for the design of next-generation field-effect transistors.