Thickness-controlled multilayer hexagonal boron nitride film prepared by plasma-enhanced chemical vapor deposition

Two-dimensional (2D) hexagonal boron nitride (h-BN) is a thin insulating material that can be used to enhance the electrical and optical properties of other 2D materials when used as a substrate or a capping layer, owing to its absence of dangling bonds on the surface. The use of multilayer h-BN films is often required in such applications to realize high material performance. However, previous works have focused mostly on the synthesis of monolayer or few-layer h-BN films. Herein we report a method to control the thickness of h-BN film up to the centimeter scale by means of plasma-enhanced chemical vapor deposition (PECVD). The thickness of the h-BN film is controlled by varying the deposition time of borazine precursor onto a monolayer h-BN film on a Pt foil substrate at room temperature. The resultant film is then annealed at high temperature (1050 °C) to increase the crystallinity of the h-BN. Monolayer h-BN film grown on Pt foil used as a buffer layer is of importance to improve uniformity and smooth surface of the multilayer h-BN film over the whole area. We further demonstrate that our multilayer h-BN film is very useful in graphene/h-BN/SiO2 heterostructures as a charge-blocking layer between graphene and SiO2.