Growth of Gallium Oxide Thin Films on Quartz Substrates Using Mist Chemical Vapor Deposition for Deep Ultraviolet Photodetectors

Abstract

Gallium oxide (Ga₂O₃), which is known as an ultra-widegap oxide semiconductor, is a promising material for applications of deep ultraviolet region photodetectors with high sensitivity. Mist chemical vapor deposition (mist-CVD) is a growth method with strong epitaxial properties and is suitable for the growth of Ga₂O₃. In this study, Ga₂O₃ thin films are grown on quartz (0001) substrates using mist-CVD at different growth temperatures to evaluate their crystal quality and photoconductivity. The gallium oxide thin films grown at 450°C were amorphous films with sparse structure, while the gallium oxide films grown at 550°C were mixture thin films of β-Ga₂O₃ and amorphous phase. MSM photodetectors with a platinum comb-type electrodes were fabricated to evaluate their photoconductivity and visible-rejection-ratio (VRR) values. As a result, Ga₂O₃ thin films grown at 550°C exhibited large photoconductivity and high VRR value of 10^5.1 at 12 V and 10^5.4 at 24 V. As well, the dark current and photocurrent under halogen lamp illumination was under the detection limit (<100 pA). These results indicate that Ga₂O₃ thin films grown using mist-CVD can be a good candidate for deep-ultraviolet photodetectors.