Study of gan epilayers grown on sapphire by hvpe using metallographic and x-ray diffraction methods
Thick GaN epilayers grown on the sapphire substrates by hydride vapor phase epitaxy in vertical reactor were studied using selective etching in molten KOH and KOH+NaOH eutectic and X-ray diffraction techniques. The surface morphology defects were classified. The main types of defects revealed by chemical etching are nanopi pes and dislocations. Effect of epilayer thickness on dislocation densitywas demonstrated. The dislocation densities around (2-3) 107 см-2 were achieved for the layers more than 100 Mm thick.