Effect of Supply Direction of Precursors on a-Plane GaN Low Angle Incidence Microchannel Epitaxy by Ammonia-Based Metal–Organic Molecular Beam Epitaxy

Abstract

The effects of varying the supply direction of precursors on a-plane GaN low angle incidence microchannel epitaxy by ammonia-based metal–organic molecular beam epitaxy were studied. Lateral growth was found to be wider when precursors were supplied from the [0001] direction than from the [0001̄] direction. The (0001̄) face formed on the supply side suppressing lateral growth when the precursors were supplied from the [0001̄] direction, while lateral growth was enlarged by the intersurface diffusion of adatoms from the side to the top when supplied from the [0001] direction. A smaller cross-section of lateral growth was experimentally observed when the (0001̄) face appeared on the supply side, which suggests that the chemical character of the side also affects lateral growth. The offset angle of the opening is another important factor for determining the lateral growth, which largely affects the formation of facets on the sides and, consequently, the grown shape.