Growth and characteristics analysis of the thermal oxide grown on gallium nitride

摘要

The thermal oxidation process at 900°C in dry oxygen O_2 on gallium nitride (GaN) and the physical characteristics of the oxide thin films are investigated by spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS). XPS spectra of Ga_(3d) and O_(1s) core levels indicates that the thermal oxide is gallium oxide (Ga_2O_3), and the existence of much O loss on the surface induces the ratio of Ga to O is more than 1. SE metrical results indicate the average grown rate is ～25nm/h. The refractive index of Ga_2O_3 is 1.8～2.1 in the wavelength range of 300～800nm, which agrees with the prevenient study results. However, anomalous refractive phenomenon appeares at 300～400nm, the reason is probably interrelated with the strong absorbance of GaN in this wavelength range and needs deeper study later. Such stable and controllable Ga_2O_3 thermal growth process is significant for GaN gate dielectric applications in the future.