A novel growth method of freestanding GaN using in situ removal of Si substrate in hydride vapor phase epitaxy

We demonstrate the freestanding GaN of 2 in. diameter and 400 μm thickness grown from Si substrate by hydride vapor phase epitaxy. To prevent the formation of cracks in the GaN layer during cooling, the Si substrate was removed at high temperature, which successfully suppressed the tensile stress evolution in GaN. The freestanding GaN exhibited high quality with FWHM of 65 arcsec in (0002) X-ray rocking curve and etch pit density of less than 1 × 106/cm2. It may be possible to fabricate high-quality freestanding GaN substrates of over 8 in. diameter using this method.