Growth of epitaxial AlxGa1−xN films by pulsed laser deposition

Epitaxial AlxGa1−xN films have been grown on c-cut sapphire substrates at 800 °C and 10−2 Torr N2 by pulsed laser deposition (PLD) using a KrF laser. Throughout the composition range from x=0 to 0.6, the films show epitaxial patterns in reflection high-energy electron diffraction, in agreement with the results from x-ray diffraction. The lattice constants of the films vary linearly with x. The composition dependence of the band gaps of the films deviates from linearity and bows downward. This letter reports the application of PLD to controlling the lattice constant and band gap by varying the proportion of AlN and GaN in the target mixture.