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

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/XAuY (X, Y = Se, Te) heterostructures were systematically analyzed through first-principles calculations. G/SeAuSe, G/SeAuTe, and G/TeAuSe are n-type Schottky contacts with = 0.40, 0.38, and 0.55 eV respectively, whereas G/TeAuTe is a p-type Schottky contact with = 0.39 eV. In G-based heterostructures consisting of SeAuTe 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 values of G/SeAuTe and G/TeAuSe. Furthermore, vertical strain and external electric field, which influence charge transfer, are applied to G/XAuY heterostructures to modulate their SBHs. Taking G/TeAuTe 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/XAuY for further research.