Morphology and X-ray diffraction peak widths of aluminum nitride single crystals prepared by the sublimation method

AIN single crystal is one of the promising materials for substrates of GaN-based laser diodes. We prepared aluminum nitride single crystals by the sublimation method and characterized them. The crystals are transparent and slightly yellow. Some crystals are needle-shaped with a hexagonal cross section, diameter of 0.5 mm and length of 3 mm, grown parallel to \001\. Other crystals are plate-shaped with a maximum width of 3 mm, 5 mm length and 0.5 mm thickness, grown with a large (001) face. Also, other crystals are needle-shaped with a rectangular cross section, width of 1 mm, 7 mm length and 0.3 mm thickness, grown with a large (101) face. Their widths of X-ray rocking curves is about 39 arcsec, with a full width at half-maximum, 203 arcsec and 12 arcsec, respectively. The orientation of AIN single crystal axis is sufficient for use in substrates for GaN-based diodes.