Analysis of HVPE grown AlGaN layers on honeycomb patterned sapphire

S. Fleischmanna, A. Mogilatenkoa,b, S. Hagedorna, E. Richtera, D. Goranc, P. Schäferb, U. Zeimera, M. Weyersa, G. Tränklea

Published in:

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

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Abstract:

Thick AlxGa1-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.

a Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
b Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
c Bruker Nano GmbH, Am Studio 2d, 12489 Berlin, Germany

Keywords:

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