Contaminant-Free Wafer-Scale Assembled h-BN/Graphene van der Waals Heterostructures for Graphene Field-Effect Transistors

Van der Waals heterostructures have attracted much attention among those designing electronic and optical devices. The core issue for the commercial production of such devices is the large-scale fabrication of two-dimensional materials with clean interfaces at low cost. Here, a large-scale assembly method for an h-BN/graphene van der Waals heterostructure with a continuous layered structure and a clean interface was demonstrated. The two-step electrochemical delamination and the re-spin coating support layer methods were used to assemble the van der Waals heterostructure. Without annealing, graphene in the heterostructure exhibits weak doping and low strain, which is close to the intrinsic properties of graphene. Graphene field-effect transistors fabricated with h-BN/graphene heterostructures show a near-zero Dirac voltage, coincident forward-backward scanning transfer curves, and high carrier mobility. Our contaminant-free transfer technique presented here offers a solution for low-cost large-scale clean transfer of two-dimensional material heterostructures and clean fabrication of their field-effect transistors. This work provides the possibility for the commercial production of graphene-based electronic devices.