Tunable Schottky contacts in graphene/XAu4Y (X, Y = Se, Te) heterostructures.

Abstract

Graphene-based (G-based) heterostructures have recently attracted considerable research interest in the field of two-dimensional nanodevices owing to their superior properties compared with those of separate monolayers. In this study, the electronic properties and Schottky barrier heights (SBHs) of G/XAu4Y (X, Y = Se, Te) heterostructures were systematically analyzed through first-principles calculations. G/SeAu4Se, G/SeAu4Te, and G/TeAu4Se are n-type Schottky contacts with Φn = 0.40, 0.38, and 0.55 eV respectively, whereas G/TeAu4Te is a p-type Schottky contact with Φp = 0.39 eV. In G-based heterostructures consisting of SeAu4Te that has a 0.22-Debye intrinsic dipole moment, the intrinsic dipole moments in different directions enhance or weaken the interfacial dipole moments corresponding to the charge transfer at the interface, resulting in different Φn values of G/SeAu4Te and G/TeAu4Se. Furthermore, vertical strain and external electric field, which influence charge transfer, are applied to G/XAu4Y heterostructures to modulate their SBHs. Taking G/TeAu4Te as an example, the p-type contact transforms into an almost ohmic contact with decreasing vertical strain or positive external electric field. The findings of this study can provide insights into the fundamental properties of G/XAu4Y for further research.