Preparation of AlGaN/GaN Heterostructures on Sapphire Using Light Radiation Heating Metal-Organic Chemical Vapor Deposition at Low Pressure

AlGaN/GaN heterostructures on sapphire substrate were fabricated by using light radiation heating metalor-ganic chemical vapor deposition. Photoluminescence excitation spectra show that there are two abrupt slopes corresponding to the absorption edges of AlGaN and GaN, respectively. X-ray diffraction spectra clearly exhibit the GaN (0002), (0004), and AlGaN (0002), (0004) diffraction peaks, and no diffraction peak other than those from the GaN 0001 and AlGaN 0001 planes is found. Reciprocal space mapping indicates that there is notilt between the AlGaN layer and the GaN layer. All results also indicate that the sample is of sound quality and the A1 composition in the AlGaN layer is of high uniformity.