Epitaxial Growth of GaN/AlN on h-BN/Si(111) by Metal-Organic Chemical Vapor Deposition: An Interface Analysis

Among III-nitride semiconductors, hexagonal boron nitride (h-BN) has a two-dimensional crystal structure and can be used as an insulator for nanotransistors or a substrate release layer for flexible electronics, which heavily rely on its interface properties. In this study, h-BN films were successfully grown on 150 mm Si(111) substrates by metal-organic chemical vapor deposition using AlN as a nucleation layer, and van der Waals epitaxy of GaN on the h-BN films was investigated, including the challenges of exfoliation of epilayers. As a result of the accumulated stress in GaN films during growth, self-exfoliation of GaN films was observed on GaN of thickness 1 μm and more. This issue was resolved by decreasing the h-BN thickness from 8 to 3 nm and lower, which results in improved crystal quality as evidenced by the smaller linewidth of the (0002) GaN X-ray rocking curves. Based on the exfoliation behavior of a series of GaN grown with different thicknesses, a self-exfoliation mechanism was proposed and an interface binding energy of 54 meV was estimated for the h-BN/AlN interface.