Abstract:
The epitaxial layers of AlN$(11\bar{2}2)$ with a thickness of 3.9 $\mu$m were grown on a GaN$(11\bar{2}2)$/$m$-Al$_2$Î$_3$ template by hydride vapour-phase epitaxy (HVPE). The template consisted of GaN$(11\bar{2}2)$ and buffer AlN s with thicknesses of 2.7 $\mu$m and 0.6 $\mu$m, respectively, grown on a sapphire substrate of orientation $(10\bar{1}0)$. It is shown that the full width at half maximum (FWHM) for the diffraction peaks of GaN$(11\bar{2}2)$/$m$-Al$_2$Î$_3$ and AlN$(11\bar{2}2)$ are 30 and 20 arc minutes, respectively. It was found that the epitaxy of AlN$(11\bar{2}2)$ on the template leads to an increase in the size of crystal blocks in the AlN$(11\bar{2}2)$ layer. It is assumed that the improvement in the quality of the AlN$(11\bar{2}2)$ layer occurs due to its predominant growth in the tangential direction due to the relatively low lattice difference at the AlN$(11\bar{2}2)$/GaN$(11\bar{2}2)$ heterogeneous boundary.
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