Growth of epitaxial GaN films using ZnO buffer layer by pulsed laser deposition

GaN films and ZnO buffer layers have been deposited on c-cut sapphire substrates by pulsed laser deposition (PLD) employing a KrF laser (λ = 248 nm). The influence of the deposition parameters, such as substrate temperature and gas pressure during growth, have been studied. GaN films grown above 700°C are single crystalline and the full width of half-maximum (FWHM) of the GaN (0002) peak decreases to 0.37° as the growth temperature increases to 800°C. The optimum growth pressure for GaN is determined to be 0.01 torr N₂. The optical transmission below the bandgap of the GaN film grown at this pressure is over 85%.