Crystallographic orientation and strain distribution in AlN seeds grown on 6H–SiC substrates by the PVT method

Abstract

As a nitride semiconductor with a wide bandgap, AlN is a promising material because of its broad applications in electronics and opto-electronics. In this study, a primary AlN seed was prepared with 6H–SiC as the foreign substrate by using the physical vapor transport (PVT) method. Results from X-ray diffraction, Raman spectroscopy and electron backscatter diffraction show that the growth pattern of AlN on 6H–SiC is [0001]_AlN‖[0001]_6H–SiC and [100]_AlN‖[100]_6H–SiC. Based on this finding, a particle model of AlN growth on the 6H–SiC substrate is drawn, and the bonding mode during the growth process is analysed. The internal stress of this growth mode is evaluated by the texture component and Raman spectra. An almost uniform colour of the texture component confirms the consistency of the structure. The Raman spectra and theoretical mode of the AlN seed show that the stress remains at a very low level after the growth thickness exceeds a certain value, and then decreases as the AlN layer becomes thicker. This in-depth study will enhance understanding of the growth mode and stress distribution of AlN grown on 6H–SiC substrate.