S. Fleischmann^a, A. Mogilatenko^a,b, S. Hagedorn^a, E. Richter^a, D. Goran^c, P. Schäfer^b, U. Zeimer^a, M. Weyers^a, G. Tränkle^a

Published in:

J. Cryst. Growth, vol. 414, pp. 32-37 (2015).

Abstract:

Thick Al_xGa_1-xN layers were grown by hydride vapor phase epitaxy on hexagonally patterned sapphire substrates. Non-c-planar growth is found inside the etched honeycombs which in part hinders coalescence of the c-plane AlGaN layer growing on top of the ridges. From X-ray diffraction, electron backscatter diffraction and scanning electron microscopy, the orientations of the parasitic crystallites were identified as {11-22} and {1-103} AlGaN growing on m-plane sapphire sidewalls as well as c-plane oriented AlGaN growing on n-plane sidewall facets which are located in the corners of the combs. According to the geometry of parasitic crystallites, it is further observed, that the semipolar growth occurring on sapphire m-plane sidewalls does not hinder the coalescence of c-plane AlGaN growing on top of the ridges, whereas fast propagation of parasitic crystallites nucleating on n-plane sidewall facets leads to delayed layer coalescence.

Keywords:

Crystal structure, Crystallites substrates Hydride vapor phase epitaxy, Nitrides, Semiconducting III-V materials

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