Impacts of oxygen radical ambient on structural and optical properties of (AlGa)2O3 films deposited by pulsed laser deposition

We report on the impacts of oxygen radical ambient for (AlGa)2O3 films grown on sapphire substrates by pulsed laser deposition (PLD). All the films showed a monoclinic crystal structure and high transmittance in the ultraviolet and visible wavelength range. The surface roughness was less than 3 nm for all films, and the surface morphology has changed by applying oxygen radical ambient. The growth rate was faster in oxygen radical ambient compared with conventional oxygen ambient. Oxygen radical ambient has influences on the crystal quality of the (AlGa)2O3 films. The Ga content in β-(AlGa)2O3 films grown with oxygen plasma assistance was higher than that without the oxygen plasma, indicating the suppression of the re-evaporation of Ga related species from the film surface by plasma assistance during the PLD process.