Effect of growth temperature on the properties of p-type GaN grown by plasma-assisted molecular beam epitaxy

p-type GaN films were grown at two different temperatures, 650 and 700 degrees C, by plasma-assisted molecular beam epitaxy (PAMBE) using a radio frequency (RF) plasma source. High hole concentrations of the order of 10(18) cm(-3) were achieved for both films without any post-growth treatment. For (0 0 0 2) diffraction from the p-type films grown at 700 degrees C, the full-width at half-maximum (FWHM) of the double-crystal X-ray rocking curve was 7.8 arcmin, the smallest ever reported for p-type GaN films grown on sapphire substrates. The room-temperature photoluminescence (PL) measurements on both films showed that band edge emission at 365 nm dominated the PL spectra of the films grown at 700 degrees C, while emission at 413 nm, associated with deep Mg complexes, dominated those of the films grown at 650 degrees C. The films grown at 700 degrees C showed better crystalline quality and optical properties than those grown at 650 degrees C.