Growth and etching characteristics of gallium oxide thin films by pulsed laser deposition

The gallium oxide films were deposited on (0 0 1) sapphire at various substrate temperatures from 400 to 1000 °C by pulsed laser deposition using a KrF excimer laser. The etching treatments for as-grown gallium oxide were performed in a 49 mol% HF solution at room temperature. The structural, optical and etching properties of the grown films were investigated in terms of high resolution X-ray diffraction, optical transmittance, atomic force microscopy, and X-ray photoelectron spectroscopy. The phase transition from amorphous to polycrystalline β-Ga2O3 structure was observed with increasing growth temperature. From the optical transmittance measurements, the films grown at 550–1000 °C exhibit a clear absorption edge at deep ultraviolet region around 250–275 nm wavelength. It was found that the optical band gap of gallium oxide films increased from 4.56 to 4.87 eV when the substrate temperature increased from 400 to 1000 °C. As the substrate temperature increases, the crystallinity of gallium oxide film is enhanced and the etching rate is decreased. The high etching rate of 490 nm s−1 for gallium oxide film grown at 400 °C could be due to its amorphous phase, which is referred to higher void ratio and looser atomic structure.

► The β-Ga2O3 thin films are prepared by pulsed laser deposition.
► The substrate temperature affects the structural, optical and etching properties of the grown films.
► The optical transmittance and band gap of the films increased with increasing the substrate temperature.
► The etching treatments for gallium oxide are performed in 49 mol% HF solution at room temperature.
► The gallium oxide thin film grown at 400 °C has the highest etching rate of 490 nm s−1.