This paper presents the results of studying Al ₗ Ga ₁-ₗ N layers grown by molecular beam epitaxy ay different molar content of aluminum on Al ₂ O ₃ substrates by scanning electron microscopy and transmission electron microscopy. It is shown that the inversion domains in the AlN buffer layers do not grow to the film surface during the further growth of Al ₗ Ga ₁-ₗ N layers with a molar aluminum content x 0. 2. In the layers with a molar aluminum content 0. 2 x 0. 5 above the inversion domains, bulk plateau-shaped defects are formed to extend to the depth more than 200 nm and, at x 0. 5, the plateau-shaped defects grow through the entire Al ₗ Ga ₁-ₗ N layer.
Osinnykh et al. (2025) studied this question.