Heteroepitaxial lateral overgrowth of GaN on periodically grooved substrates: A new approach for growing low-dislocation-density GaN single crystals

Using periodically grooved substrates, we propose a new approach to the growth of low-dislocation-density GaN single crystal. Three different substrates of basal-plane sapphire, 6H-SiC(0001)(Si) and Si(111) were used. Each substrate's surface geometry was formed as periodical straight trenches oriented in either the (1100)(GaN) or (1120)(GaN) direction. No selective-growth mask of dielectric or metallic materials was deposited on any part of the substrates during the growth. The laterally grown area had etch pit densities of 4 x 10(6) cm(-2) or less.