Remote Epitaxy of Cubic Gallium Nitride on Graphene-Covered 3C-SiC Substrates by Plasma-Assisted Molecular Beam Epitaxy

Remote epitaxy is a relatively new area of research that offers several advantages, including the potential to reduce the influence of lattice mismatch and the ability to exfoliate films easily. This work is focused on adapting this growth method for the epitaxy of cubic gallium nitride (c-GaN), a metastable phase. However, one faces challenges in enforcing the nucleation of the metastable cubic phase due to the weaker interactions between the substrate and the epitaxial layer compared to conventional epitaxy. Initially, only polycrystalline wurtzite gallium nitride could be grown. However, by optimizing the growth conditions and adding a cubic aluminum nitride buffer layer, predominantly cubic gallium nitride layers can be grown. High-resolution X-ray diffraction measurements confirm that the percentage of hexagonal inclusions is reduced from 80% to 23%.