Under the investigated growth conditions this high crystal quality can be maintained both along the axial direction and within lateral growth directions. The absence of basal plane dislocations in homogeneous crystal regions void of macroscopic defects can be linked to the low-stress growth conditions. The total dislocation density of 2 × 10 3 cm −2 as determined by X-ray topography is low and dislocations are largely threading edge dislocations of b = 1/3〈11 20〉 type.
X-ray diffraction (0 110) rocking-curve mappings of representative wafer cuts reveal a low mean FWHM of 13.4 arcsec, indicating the generally high crystal quality. Defect types and densities were analyzed along axial as well as lateral growth directions. AlN slices from bulk crystals grown under low thermomechanical stress conditions via the physical vapor transport (PVT) method were analyzed by X-ray methods to study the influence of the growth mode on the crystal quality.
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