Evaluation of AlN single-crystal grown by sublimation method

AlN single crystals with thicknesses from 3 μm to 4 mm were grown on SiC substrates by the sublimation method. Evaluations of crystalline quality were performed by X-ray diffraction (XRD), transmission electron microscope (TEM) and etch pit density (EPD) measurement. The FWHM of the XRD rocking curve for AlN (101¯0) reflection was as small as 26 arcsec for the sample of 4 mm thickness, and the dislocation density was estimated to be less than 106 cm−2 by EPD measurement in spite of the large lattice mismatch of 1% between AlN and SiC. TEM observation was conducted to investigate the mechanism of the improvement of the crystalline quality. We observed the significant reduction of dislocations above the interface, allowing growth of 3 μm–4 mm thick AlN with high crystalline quality. These results show that the commercial production of large-sized, high-quality substrates of AlN single crystal is possible using the sublimation technique.