Growth of thick GaN on the (0001) Al2O3 substrate by hydride-metal organic vapor phase epitaxy

We report on the crystal quality of thick GaN layers grown on (0001) Al2O3 substrates by newly developed hydride-metal organic vapor phase epitaxy (H-MOVPE) technique. The effects of process parameters on the growth rate were investigated, and the highest growth rate was achieved to be ∼ 90 μm/h. The X-ray diffraction measurements showed that the layer grown by H-MOVPE on (0001) Al2O3 without any buffer layer has good crystallinity with rocking curve FWHM of the (0002) reflection of about 500 arcsec. Films grown with LT-GaN seed layer of ∼ 20 nm thickness showed excellent surface morphology with rocking curve FWHM of the (0002) reflection of about 300 arcsec. The photoluminescence spectra of the films showed a strong band edge emission at 3.47 eV with a FWHM of 54 meV at room temperature, indicating the thick GaN layer grown on (0001) Al2O3 with LT-GaN seed layer is of device-grade quality.