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AlN/SiC epitaxial wafers were fabricated using hydride vapor phase epitaxy. The thickness of AlN layer was varied from 0.1 to 0.5 μm. Surface of AlN layers was characterized by high-energy electron diffraction and atomic force microscopy. The crystal structure of AlN layers was studied using X-ray diffraction. The minimum value of the full width at half maximum of ω-scan (0002) reflection rocking curve was about 120 arcsec. The specific resistivity of AlN was measured in the temperature range from 300 to 700 K.

The n-type doping of GaN by hydride vapor phase epitaxy (HVPE) using undoped single crystalline Si as a dopant source has been demonstrated. The doping has been realized in a wide range of Si atomic concentration (from

GaN bulk crystals up to 2.5-inch diameter were grown from melt-solution. Properties of these crystals were investigated using Auger electron spectroscopy, X-ray diffraction and photoluminescence.

We analyse the dislocation distribution in GaN and AlN bulk crystals by transmission electron microscopy and X-ray diffraction. The crystals are grown by hydride vapour phase epitaxy onto 6H-SiC[0001] and Si(111) substrates. Two essentially different dislocation populations are observed: (i) a-type dislocations that show efficient dislocation density reduction (down to 4 × 105 cm–2) and (ii) a, (a + c) and c-type dislocations each type in a considerable density with less efficient dislocation reduction. We evaluate the dislocation processes that result in this different behaviour as dependent on the dislocation population.