Suppression of cracks and V-shaped defects, and improvement of reflectivity of GaN/AlGaN distributed Bragg reflectors by insertion of multiple interlayers

Abstract

GaN/AlxGa1–xN distributed Bragg reflectors (DBRs) for the near-ultraviolet region have been grown on sapphire substrates by metal-organic chemical vapor deposition. In order to suppress the generation of cracks and V-shaped defects on the surface of the DBRs, AlGaN/AlN superlattices and step-graded multiple AlGaN layers were inserted prior to or during the growth of the DBRs. By optimizing those layers, the reflectivity of a 40-pair GaN/Al0.35Ga0.65N DBR was increased up to 96% without any cracks and V-shaped defects. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)