Gas-phase parasitic reactions and Al incorporation efficiency in light radiation heating, low-pressure metal–organic chemical vapor deposition of AlGaN

Abstract

AlGaN epilayers were successfully grown using light radiation heating, metal–organic chemical vapor deposition (MOCVD). The optimized growth temperatures are between 950 and 1000, which are lower than those of normal RF-heating MOCVD. X-ray diffraction (XRD) spectra indicated that the films are of high crystalline quality. Photoluminescence excitation (PLE) spectrum shows an abrupt absorption edge of the AlGaN layer, which also indicates that the samples are of sound optical quality and with Al composition uniformity. The results indicate that the incorporation efficiency of Al is as high as that of Ga, which is beneficial for the improvement of the Al composition uniformity in the AlGaN films. A model of the influences of parasitic reaction on the Al composition in the AlGaN films is developed based on previous works. Light radiation may depress the parasitic reaction and thus improve the incorporation efficiency of Al into the AlGaN films and the Al composition uniformity of the AlGaN layers. Therefore, a high-quality growth of AlGaN may take place at relatively low temperatures in comparison with the growth in RF-heating MOCVD.