High-quality GaN films of 320 μm thickness are deposited on low-temperature HVPE-GaN/c-Al2O3 templates by hydride vapor phase epitaxy(HVPE) with RF-ZnO as the buffer layers.The crystal properties of ZnO buffers and thick GaN films are detected by double crystal X-ray diffraction(DCXRD),atomic force microscopy(AFM) and scanning electron microscope(SEM).As a result,the full width at half maximum(FWHM) of GaN(0002) double crystal x-ray diffraction rocking curve is 336.15 arcsec and the threading di...