Amorphous GaN (a-GaN) films were deposited at a low temperature below 500°C by compound-source molecular beam epitaxy (CS-MBE). The relationship between excess Ga and its oxidation in the deposited GaN films is reported. X-ray photoelectron spectroscopy (XPS) revealed that the excess Ga in deposited films was oxidized in the air and converted to gallium oxide. By increasing the substrate temperature, the total amount of gallium oxide in the deposited films decreased due to the reduction of the excess Ga. Cathodoluminescence (CL) intensity from the UV to the blue spectral regions increased with as the amount of gallium oxide in the deposited films decreased.

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Schottky-type light-emitting diodes (ST-LEDs) were fabricated using GaN epilayers grown on (0001) sapphire substrates by metal-organic vapor phase epitaxy. The UV light emission (374 nm) was observed from the integrated ST-LEDs under reverse bias conditions. The integrated ST-LEDs are good candidates for the UV excitation sources of flat-panel display systems combined with red, green and blue phosphors.