Liquid-Phase Deposition of Al[sub 2]O[sub 3] Thin Films on GaN

Abstract

Thin films of aluminum oxide on substrates were grown by the process of low-temperature liquid-phase deposition (LPD), in which aluminum sulfate with crystallized water and sodium bicarbonate were used as the precursors. The pH value of the growth solution plays an important role in the deposition process. The best quality of the oxide thin film was obtained at the pH value of 3.80, while the growth rate was at the optimized concentration values of and and at the temperature of 30°C. The films were characterized by means of X-ray photoelectron spectroscopy, Auger electron spectroscopy, and atomic force microscopy. It was found that the leakage current density of thin oxide film was between and at a negative electric field of , with the breakdown electric field being greater than . After annealing the oxide at for , the leakage current density was lowered to the value of at the negative electric field of . The oxide-semiconductor interface state density as calculated from the capacitance-voltage curve was .