MOCVD growth of high reflective GaN/AlGaN distributed Bragg reflectors

GaN/AlGaN distributed Bragg reflectors have been grown by low-pressure metal organic chemical vapor deposition. Those structures were fabricated on the atmospheric pressure grown GaN layer on sapphire substrate. The aluminum content in low-pressure grown AlGaN layers was estimated to be 0.60 by X-ray diffraction. The GaN layers grown under the low-pressure condition in GaN/Al_0.60Ga_0.40N multilayer were compressively strained. The flat surfaces without cracks were successfully obtained for the growth of GaN/Al_0.60Ga_0.40N distributed Bragg reflector. For the 45.5 pairs, a peak reflectivity of over 98% was obtained at a wavelength of 421 nm.