SiO2 insulating layers were first deposited onto GaN by photochemical vapor deposition (photo-CVD) technology using a deuterium (D2) lamp as the excitation source. Physical, chemical, and electrical characteristics of the Al/SiO2/GaN metal-insulator-semiconductor (MIS) capacitors are reported for the first time. It was also found that the limiting factor of SiO2 growth rate was the number of SiH4 and O2 molecules available to provide excited Si and O atoms. Furthermore, it was found from high-frequency capacitance-voltage measurements that the photo-CVD SiO2/n-GaN interface state density, Dit, was estimated to be 8.4 × 1011 cm-2 eV-1 for the photo-CVD SiO2 layers prepared at 300°C. With an applied field of 4 MV/cm, the oxide leakage current density was found to be only 6.6 × 10-7 A/cm2.
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