Thick films of GaN were studied by x-ray diffraction and Raman spectroscopy. The GaN thick
films were deposited on (0001) sapphire using ultrahigh-rate magnetron sputter epitaxy with
typical growth rates as high as 10–60 μm/min. The width of the x-ray rocking curve from the
(0002) reflection for the sample produced by this technique is∼ 300 arcsec, which is
unprecedented for GaN produced by a sputtering-type process. Our recent sample shows an
x-ray rocking curve width of 240 arcsec. Only allowed modes were observed in the polarized …