Low temperature growth of (AlGa)2O3 films by oxygen radical assisted pulsed laser deposition

Abstract

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.