Effects of pressure difference and temperature on the α-Ga2O3 growth by mist chemical vapor deposition

As a novel wide-bandgap semiconductor material, α-Ga2O3 has great potential in high-power devices and deep ultraviolet photodetectors. However, for α-Ga2O3 growth by mist chemical vapor deposition (mist-CVD), the clustering of mist flow often appears, resulting in a poor crystallinity and rough surface of the α-Ga2O3 films. In this study, we established a home-made mist-CVD system with a novel heating structure and a cuboid chamber. The effects of the pressure difference between the inlet and outlet of the reaction chamber as well as the growth temperature on α-Ga2O3 films growth were systematically investigated. High quality α-Ga2O3 thin films with smooth surface were prepared at 450 °C under 80 Pa pressure difference due to the weakened clustering effect of mist flow. The surface Root-Mean-Square (RMS) roughness of the α-Ga2O3 films was as low as 1.32 nm, and the growth rate could reach 26.9 nm/min. The transmittance was higher than 80% in the near-ultraviolet to visible light region, and the optical band gap was determined to be 5.23 eV.