Van der Waals Self-Assembled Silica-Nanosphere/Graphene Buffer Layer for High-Quality Gallium Nitride Growth

In the van der Waals epitaxy of III-nitride semiconductor materials, graphene plays an increasingly important role. In this work, to improve the quality of the gallium nitride (GaN) film on sapphire, we innovatively propose a composite insertion layer of graphene/silica nanospheres (G/S-n). The G/S-n composite insertion layer successfully realizes van der Waals self-assembly for the silica nanospheres. The G/S-n buffer layer can effectively block threading dislocations during the growth of GaN materials, and experimental results show that it significantly enhances the quality of the GaN film. The screw- and edge-dislocation densities are reduced from 1.75 x 10(8) to 7.81 x 10(7) cm(2) and from 8.66 x 10(8) to 5.84 x 10(8) cm(2), respectively. This work provides a foundation for future research into the van der Waals epitaxy of nitrides.