Tunable Schottky Barrier in Graphene/xag4y (X, Y = S, Se, Te) Heterostructures

•Graphene/XAg4Y (X, Y = S, Se, and Te) possess different graphene/X interface, resulting in various Schottky barrier heights and contact types.•Schottky barrier heights and contact types can be modulated by the vertical strain and external electric field.•The mechanism of the tunable Schottky barrier via the vertical strain and external electric field are investigated.•Vertical strain or external electric field underlies that the relative Dirac-cone position of graphene in heterostructures can be tuned.