Tunable Schottky contacts in graphene/XAu₄Y (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/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 Φ_n = 0.40, 0.38, and 0.55 eV respectively, whereas G/TeAu₄Te is a p-type Schottky contact with Φ_p = 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 Φ_n 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.