Effect of Ga flux and rf-power on homoepitaxial growth of single crystalline GaN films

We investigated the effect of Ga flux and plasma power on the homoepitaxial growth of GaN epitaxial films by Molecular Beam Epitaxy (MBE) on MOCVD-grown GaN templates on c-sapphire substrates. The grown GaN films were characterized by several techniques to assess their structural and morphological properties. The surface morphology, dislocation densities and crystalline quality were found to be contingent on two parameters namely, Ga flux and the RF-plasma power. It was observed that, on increasing the Ga flux at constant rf-power, the crystalline quality as well as the surface morphology of the GaN film improved. On increasing the plasma power at low Ga flux, the crystallinity of the grown homoepitaxial film further enhanced significantly, but the surface roughness slightly increased due to the formation of hexagonal islands. The dependence of growth parameters on crystalline quality, threading dislocation densities, and surface morphology has been studied.