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(Al,Ga)N overgrowth over AlN ridges oriented in [1120] and [1100] direction
V. Kueller1, A. Knauer1, U. Zeimer1, H. Rodriguez1, A. Mogilatenko3, M. Kneissl1,2, and M. Weyers1
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
2 Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
3 Institut für Physik, Humboldt-Universität-Berlin, Newtonstr. 15, 12489 Berlin, Germany
Published in:
phys. stat. sol. (c), no. 8, vol. 7-8, pp. 2022-2024 (2011).
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract:
Epitaxial lateral overgrowth of 1.5 µm wide AlN ridges
with 1.5 µm spacing with AlGaN or AlN was investigated
by electron microscopy and cathodoluminescence.
Overgrowth of [1100] oriented stripes leads to relatively
smooth c-plane AlGaN surfaces while on [1120] oriented
stripes strongly facetted surfaces evolve. The growth on
the different facets leads to strong compositional fluctuations.
These fluctuations can be prevented by the growth
of binary AlN over the ridges instead of AlGaN. Only the
[1100] oriented ridges formed smooth surfaces, suitable
for subsequent deposition of AlGaN with homogeneous
composition. The lateral epitaxial overgrowth leads to a
remarkable reduction in threading dislocation density as
shown by TEM and X-ray diffraction. The critical thickness
of AlN before cracking was significantly increased
in comparison to unpatterned growth. The resulting AlN
template is a promising ultraviolet transparent template
for LED.
Keywords:
metalorganic vapour phase epitaxy, epitaxial lateral overgrowth, AlN, nitrides.
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