In this research effort, epitaxial lateral overgrowth (ELOG) of GaN on sapphire was performed by low-pressure metalorganic chemical vapor deposition (MOCVD) in a horizontal reactor. All ELOG growths were stopped prior to complete coalescence, and the resulting cross-sections were characterized by scanning electron microscopy (SEM). Both vertical {1120} and inclined sidewalls were observed. Inclined {112n}sidewalls of various angles (n ≈ 2-2.2) were found as previously reported in the literature¹. Both one-step and two-step ELOG processes were used to control the overgrowth geometry. It was confirmed that sidewall formation and growth rates are closely correlated with multiple parameters including temperature and V/III ratio¹. It was also found that substrate rotation greatly influences sidewall evolution and vertical growth rate. A conceptual model was begun to completely describe the ELOG process in a horizontal reactor. It is speculated that the different sidewalls observed as a function of substrate orientation result from variation in the local V/III ratio. Once developed, the final model will be used to control the sidewalls in the growth of ELOG structures for the fabrication of novel optoelectronic devices.

Date Published: 24 October 2005
PDF: 8 pages
Proc. SPIE 6017, Nanophotonics for Communication: Materials and Devices II, 60170D (24 October 2005); doi: 10.1117/12.630965

Published in SPIE Proceedings Vol. 6017:
Nanophotonics for Communication: Materials and Devices II
Nibir K. Dhar; Achyut K. Dutta; Kiyoshi Asakawa, Editor(s)