Comparison of HVPE GaN films and substrates grown on sapphire and on MOCVD GaN epi-layer

In this study, we report the results of comparison of GaN mm properties grown on bare sapphire and on MOCVD GaN epi-layer. Comparing with properties of two GaN films, we used double crystal X-ray diffraction (DCXRD), scanning electron microscopy and cathodoluminescence (CL) spectroscopy and imaging techniques. As a result of these measurements, we found that GaN films grown on MOCVD GaN epi-layer are of better quality than GaN films grown on sapphire substrate. After removing the sapphire substrates, the quality of GaN substrate grown on MOCVD GaN epi layer is much better than that of GaN substrate grown on sapphire. As a result, we found that nucleation layer such as MOCVD GaN epi-layer influences the crystal and optical properties of HVPE GaN film. (C) 2000 Elsevier Science B.V. All rights reserved.