Effects of out-of-plane strains and electric fields on the electronic structures of graphene/MTe (M = Al, B) heterostructures.

Contacts between graphene and two-dimensional (2D) semiconductors have been widely investigated because of their tunable Schottky barrier height (SBH) by means of applied out-of-plane strains, electric fields, etc. Here, based on first-principles calculations, we study the effects of out-of-plane strains (a tensile or compressive strain) and electric fields on the electronic structures of graphene/MTe (M = Al, B) heterostructures. The calculated results indicate that p-type Schottky barriers are formed at the graphene/AlTe and graphene/BTe interfaces with 0.72 and 0.49 eV, respectively. The increase in the interlayer distances (tensile strains) between graphene and MTe can induce a transition from a p-type to n-type Schottky contact. On the other hand, the decrease in the interlayer distances (compressive strains) can transform graphene/MTe into semiconductors, which originates from graphene/MTe with a large compressive strain that makes the two carbon sublattices inequivalent, inducing a band gap. In addition, the applied electric fields can modulate effectively the contact formation (a Schottky or Ohmic contact) and the doping of graphene in graphene/MTe heterostructures. Our study suggests two facile methods to tune the electronic properties of graphene/MTe heterostructures and offer a possibility for graphene/MTe heterostructure-based electronic devices.