Low temperature growth of (AlGa)2O3 films by oxygen radical assisted pulsed laser deposition
Low temperature growth of β-(AlGa)2O3 films has been realized by oxygen radical assisted pulsed laser deposition. The prepared films show a good (−201) orientation perpendicular to (0001) sapphire substrates even at a deposition temperature as low as 200 °C. The influences of the substrate temperature on the structural and optical properties of the films have been systematically investigated. All the films grown at substrate temperatures from 100 to 500 °C exhibit a high transmittance of over 90% in the ultraviolet and visible range. Abrupt bandgap value variation has been observed for films deposited at substrate temperatures higher than 100 °C, which agrees with the amorphous to crystalline transition temperature evidenced by X-ray diffraction. The speed of the film thickness decrease with substrate temperature is much slower for (AlGa)2O3 films grown with oxygen radical assistance, indicating the suppression of the evaporation of volatile species with the help of oxygen radical species. The low temperature growth of β-(AlGa)2O3 films could be compatible with the established lithography of semiconductor microfabrication processes.