Epitaxial growth of GaN thin film on sapphire with a thin ZnO buffer layer by liquid target pulsed laser deposition

Epitaxially grown gallium nitride thin films were deposited on sapphire(0001) substrates with a thin zinc oxide buffer layer by a liquid target pulsed laser deposition technique. The GaN thin film optimized at a substrate temperature of 600 degrees C has an epitaxial relationship with ZnO buffered sapphire(0001) of (0001)(GaN)//(0001)(ZnO)//(0001)(sapphire), and (10(1) over bar 0)(GaN)//(10(1) over bar 0)(ZnO)//(11(2) over bar 0)(sapphire). The surface morphology was also improved by applying a ZnO buffer layer shown by scanning electron microscopy. Although the as-grown GaN thin film showed no band edge or yellow band photoluminescence at room temperature, a weak band edge luminescence of 3.42 eV could be seen at 20 K. (C) 1998 American Institute of Physics. [S0021-8979(98)02022-2]