Effects of AlN buffer layer thickness on the crystallinity and surface morphology of 10-prrs-thick a-plane AlN films grown on r-plane sapphire substrates

摘要

10-mu m-thick a-plane AIN(1120) films containing a low-temperature AIN (LT-AIN) buffer layer and a high-temperature AIN (HT-AIN) film were prepared on r-plane sapphire (1102) substrates. The crystallinity of all the samples with different LT-AIN buffer layer thicknesses was improved after thermal annealing and HT-AIN growth, mainly owing to the elimination of domain boundaries and the concurrent suppression of facet formation. The optimum crystallinity of HT-AIN films was obtained with full widths at half maximum of the X-ray rocking curves of 660 arcsec for AIN(1120) parallel to [1100]AIN and 840 arcsec for (0002) using a 200-nm-thick LT-AIN buffer layer. (C) 2016 The Japan Society of Applied Physics