The oxidation of gallium nitride epilayers in dry oxygen.

Abstract. The oxidation of GaN epilayers in dry oxygen has been investigated. The GaN epilayers, about 1 micro m thick, were grown on (0001) sapphire substrates by rapid thermal process/low pressure metalorganic chemical vapor deposition. Bulk theta - 2 theta X-ray diffraction (XRD) data showed that the slight oxidation of GaN began to occur at 800 Celsius tot 6 h. The oxide was identified as the monoclinic beta-Ga[sub 2]O[sub 3]. The GaN epilayers were completely oxidized at 1050 Celsius for 4 h or at 1100 Celsius for I h. For all samples, the strongest oxide's peak is (11-3), and (30-6) followed. There is a rapid oxidation process in the initial stage of oxidation, and a relatively slow process followed when the temperature was over 1000 Celsius. The oxidation of two stages was limited by the rate of an interracial reaction mechanism and by the diffusion mechanism, respectively. When the temperature reaches 1100 Celsius, the oxidation rate is very fast, which is considered as the results of the GaN decomposition at high temperature under atmosphere. The oxide layers were also observed by a scanning electron microscope, which shows a rough oxide surface and an expansion of the volume of 40%. The photoluminescence (PL) seriously influenced by the oxidation is also discussed. [ABSTRACT FROM AUTHOR]