Optical characterization of high quality GaN produced by high rate magnetron sputter epitaxy

摘要

The thick films of GaN were investigated using X-ray diffraction,micro-Raman spectroscopy and photoluminescence spectroscopy.The thick films of GaN were prepared on (0001) sapphire using high rate magnetron sputter epitaxy with growth rates as high as 10-60 mum/min.The width of the X-ray rocking curve ((0002) reflection) for the sample produced by this method is approx300 arc-sec.Only the allowed modes were observed in the polarized Rman spectra.The background electron concentration is lower than 3X10~(16) cm~(-3),which was determined from the Raman spectra.The phonon lifetime determined from Raman E_2~(2) mode was 1.6 ps,which is comparable to that of bulk single crystal GaN grown by sublimation (1.4 ps).The full-width-at-half-maximum of the near band-edge photoluminescence peak obtained at 77 K is approx100 meV.