Thermal and lattice misfit stress relaxation in growing AIN crystal with simultaneous evaporation of SiC substrate

Abstract

AlN single crystals were prevented from cracking by simultaneous growth and evaporation of SiC substrates. Freestanding layers (��1 mm thick) were proved continuous (non?cracked) and used as a model system to investigate the type of dislocation structure near AlN/SiC interface. Using x-ray diffraction techniques, we found that, unlike GaN films, in which high-density threading dislocations cross the film along its normal, the AlN layers possess a mosaic structure composed of low-angle subgrain boundaries. We suggest a theoretical model that describes the misfit stress relaxation in growing AlN crystal. ? 2017 Trans Tech Publications, Switzerland.