Centimeter-Sized Single-Orientation Monolayer h-BN with or without Nanovoids

Large-area hexagonal boron nitride (h-BN) promises many new applications of two-dimensional materials, like the protective packing of reactive surfaces or as membranes in liquids. However, scalable production beyond exfoliation from bulk single crystals remained a major challenge. Single orientation monolayer h-BN nanomesh is grown on 4-inch wafer single crystalline rhodium films and transferred on arbitrary substrates like SiO2, germanium or transmission electron microscopy (TEM) grids. The transfer process involves application of tetraoctylammonium bromide before electrochemical hydrogen delamination. The material performance is demonstrated with two applications. First, protective sealing of h-BN is shown by preserving germanium from oxidation in air at high temperatures. Second, the membrane functionality of the single h-BN layer is demonstrated in aqueous solutions. Here we employ a growth substrate intrinsic preparation scheme to create regular 2 nm holes, which serve as ion channels in liquids.