New buffer layer technique using underlying epitaxial A1N films for high-quality GaN growth

摘要

We demonstrate the growth of high-quality GaN using underlying high-quality epitaxial A1N films on C-plane sapphire as a new buffer layer. The obtained GaN films were atomically flat and the full width at half maximum (FWHM) values of the X-ray rocking curve (XRC) were 120arcsec and 510arcsec for (0004) and (10-10), respectively. XRC-FWHM values of the underlying A1N film were 90arcsec and 1800arcsec for (0004) and (10-10), respectively. It was found that the GaN XRC value for (0004) was much smaller than that of conventional GaN. From TEM results, it was clarified that the high-quality A1N layer had an effect in reducing the amount of screw-type threading dislocations and that the GaN/AlN interface had an effect in reducing the amount of edge-type dislocations.