International Journal of Energy Research, Vol.45, No.3, 4727-4734, 2021
The external electric-field-induced Schottky-to-ohmic contact transition in graphene/As2S3 interface: A study by the first principles
Graphene-based vertical stacking heterojunction has attracted more and more attentions in optoelectronics, nanoelectronics, and spintronics field. A low Schottky barrier height (SBH) or a low-resistance ohmic contact is desired in practical applications. In our current study, we have systematically investigated the interfacial characteristics of graphene/As2S3 heterojunction by using first-principles calculations. The results indicate that the intrinsic electronic properties of graphene and As2S3 are changed little after contacting. The Bader charge analysis indicates that the transferred amounts of electrons from As2S3 to graphene decrease with the vertical electric field ranging from -0.5 to +0.5 V/angstrom. Consequently, when the electric field value is more negative than -0.2 V/angstrom, the heterojunction maintains a p-type Schottky contact and transforms to n-type Schottky contact once the external electric field is modified from -0.2 to +0.5 V/angstrom. Finally, an ohmic contact type can be formed if the external electric field is larger than +0.5 V/angstrom. In addition, the optical absorption of the As2S3/graphene interface is significantly enhanced after contacting. Our findings imply that the SBH is tunable, which is significantly meaningful in the nanoelectronic field-effect transistors.