Gallium kinetics on m-plane GaN

In this paper, we study the adsorption/desorption kinetics of gallium on (1-100) m-GaN during molecular-beam epitaxy on bulk substrates. We demonstrate the stabilization of a laterally contracted biatomic layer of Ga containing up to ≈2.5 times the (0001) surface atom density, on top of the GaN(1-100) surface. By assessing the surface morphology of m-GaN layers grown under different Ga/N flux ratios, we show that the presence of the Ga bilayer allows the growth of atomically smooth m-GaN without accumulation of Ga droplets and in conditions (substrate temperature and Ga/N ratio) that are compatible with the growth of c-GaN.