Free Standing AlN Single Crystal Grown on Pre-Patterned and In Situ Patterned 4H-SiC Substrates

Free standing AlN wafers were grown on pre-patterned and in situ patterned 4H-SiC substrates by a physical vapor transport method. It is based on the coalescence of AlN microrods, which evolve from the apex of SiC pyramids grown on the SiC substrate during a temperature ramp up for in situ patterned substrate and SiC pyramids formed by reactive ion etching (RIE). This process yields stress-free (according XRD and Raman results) AlN single crystals with a thickness up to 400 µm and low dislocation density.