AlN and AlN/Al2O3 seed layers from atomic layer deposition for epitaxialgrowth of AlN on sapphire
S. Hagedorn1, A. Knauer1, M. Weyers1, F. Naumann2, and H. Gargouri2
Published in:
J. Vac. Sci. Technol. A, vol. 37, no. 2, pp. 020914 (2019).
Abstract:
The annealing of amorphous AlN and AlN/Al2O3 seed layers from atomic layer deposition (ALD) on sapphire substrates and their application as starting layers for metal-organic vapor phase epitaxial growth on sapphire was investigated. During annealing in hydrogen, the amorphous ALD layers become crystalline with epitaxial relation to the underlying sapphire substrate. In contrast to the pure AlN ALD seed layers, mixed layers containing Al2O3 help to avoid the formation of polycrystalline material. Additionally, such mixed ALD seeds support void formation at the AlN/sapphire interface resulting in the formation of a smooth AlN surface. This void formation can be seen in situ during AlN growth in the reflectivity at 405 nm. The tilt and twist component of the AlN grains could be decreased by increasing the annealing time at 1290°C from 1.5 to 40 min.
1 Ferdinand-Braun-Institut, Leibniz Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin, Germany
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