Phase control of semi-polar (1120) GaN on cone shaped r-plane patterned sapphire substrates

M.-T. Wang^a, F. Brunner^b , K.-Y. Liao^a, Y.-L. Li^a, S.H. Tseng^a, M. Weyers^b

^a Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1,Section 4, Roosevelt Road, Taipei 10617, Taiwan
^b Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany

Published in:
J. Cryst. Growth, vol. 371, pp. 11-16 (2013).
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Abstract:
The control of formation of semi-polar (1122) and nonpolar a-plane (1120) GaN phases on r-plane cone shaped patterned sapphire substrates (CPSS) by metalorganic vapor-phase epitaxy has been investigated. With a nucleation layer grown at 535 °C and 200 mbar, only semi-polar (1122) GaN is formed. Increasing the nucleation layer temperature to 965 °C, only (1120) GaN is grown at 200 mbar. At reduced reactor pressure of 60 mbar, phase selectivity breaks down and semi-polar (1122) and non- polar (1120) GaN exist simultaneously. The crystalline quality of a-plane GaN on r-plane CPSS can be effectively improved using optimized growth direction control.

Keywords:
A1. Nucleation; A3. Metalorganic chemical vapor deposition; B1. Nitrides; B2. Semiconducting III-V materials.

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