Significance of initial stages on the epitaxial growth of AlN using high temperature halide chemical vapor deposition



AlN epilayers were grown on c-plane Sapphire substrates using High Temperature Halide Chemical Vapor Deposition (HTCVD). Introduction of low temperature nucleation layers (NLs) prior to the high temperature AlN (HT-AlN) layers was investigated. It was found that NLs stabilizes the epitaxial growth. NL deposition conditions were optimized to improve the quality of AlN epilayers. Increasing nucleation layer deposition temperature from 650 to 850 °C as well as the growth temperature of AlN epilayers from 1200 to 1400 °C improves the structural quality and surface morphology. X-ray diffraction of θ/2θ scan confirms that AlN layers deposited on NLs are (0002) oriented and X-ray rocking curve measurement shows FWHM values as low as 864 arcsec for (0002) plane. Surface steps and specular morphology were observed for such AlN epilayers (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)