Designing sapphire surface patterns to promote AlGaN overgrowth in hydride vapor phase epitaxy

S. Fleischmann1, S. Hagedorn1, A. Mogilatenko1,2, J. Weinrich1, D. Prasai1, E. Richter1, R.-S. Unger1, M. Weyers1 and G. Tränkle1

Published in:

Semicond. Sci. Technol., vol. 35, no. 03, pp. 035028 (2020).

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Abstract:

Lateral overgrowth of patterned c-plane oriented sapphire substrates(PSS) with AlGaN using hydride vapor phase epitaxy was investigated with focus on how to suppress parasitic non c-planar crystallite nucleation and propagation. To this end, trigonal PSS was fabricated with either sidewalls parallel to sapphire {1100}-facets or parallel to sapphire {1100}-facets, which are crystallographically different due to the three-fold sapphire symmetry. X-ray diffraction-based texture analysis and SEM were applied to find two types of (0001)AlGaN||(1120)sapphire-domains solely nucleating on PSS sidewalls close to {1100}-facets. Their occurrence effectively blocks other orientations of non c-plane AlGaN crystallites allowing for quicker coalescence of c-plane AlGaN and improving overall AlGaN material quality.

1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany

Keywords:

sapphire, substrates, epitaxy, epitaxial lateral overgrwoth, aluminum nitride, gallium nitride, crystal orientation.