Growth of N-polar GaN on vicinal sapphire substrate by metal organic chemical vapor deposition

Abstract

The growth and properties of N-polar GaN layers by metal organic chemical vapor deposition (MOCVD) were reported. It is found that N-polar GaN grown on normal sapphire substrate shows hexagonal hillock surface morphology. With the misorientation angles increasing from 0.5° to 2.0° toward the a-plane of the sapphire substrate, the number of the hillock becomes less and less and finally the surface becomes flat one on the sapphire substrate with the misorientation angle of 2°. It is also found that the crystalline quality and the strain in the GaN are greatly influenced by the misorientation angle.