Sublimation growth of nonpolar AlN single crystals and defect characterization

Sublimation growth of nonpolar AlN single crystals was investigated. The crystals were prepared in two methods: By slicing along the m ‐plane from c ‐plane‐grown thick crystals, and by heteroepitaxial growth on m ‐plane SiC substrates. Defects of the crystals were observed by high‐resolution transmission electron microscope. Dislocation density in AlN/SiC (0001) decreased significantly at about 1.5 μm above the interface, while stacking faults initiated from the interface toward the growth surface in AlN/SiC (1–100). With increasing crystal thickness, the dislocation density decreases up to 5 × 104/cm2 at the thickness of 10 mm. In the AlN single crystal grown on SiC (0001), it is noteworthy that the dislocations are localized around the AlN/SiC interface and that far fewer dislocations occur near the growth surface. High‐crystallinity AlN thick single crystals could be grown on SiC (0001) substrates. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)