Nucleus and Spiral Growth Mechanisms of GaN Studied by Using Selective-Area Metalorganic Vapor Phase Epitaxy

We used selective-area metalorganic vapor phase epitaxy to study Frank-van der Merwe growth mechanisms of GaN. Step-free GaN surfaces with the diameter of 15-50 mu m were fabricated within selective areas free of screw-type dislocations. The growth rate was independent of the area, indicating multi-nucleation growth. The nucleation rate was in a range of 10(5)-10(7) cm(-2) s(-1) and the average two-dimensional nucleus density was 5 x 10(6) cm(-2). Selective areas having screw-type dislocations resulted in double growth spirals consisting of monolayer steps. The degree of supersaturation near the growing surface calculated from the interstep distance was independent of the area. (C) 2010 The Japan Society of Applied Physics