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Issue Eur. Phys. J. Appl. Phys.
Volume 22, Number 1, April 2003
Page(s) 11 - 14
Section Characterization of Materials
DOI 10.1051/epjap:2003012
Published online 25 February 2003

Eur. Phys. J. AP 22, 11-14 (2003)
DOI: 10.1051/epjap:2003012

High-quality GaN on intentionally roughened c-sapphire

Y. Golan1, P. Fini2, D. Dahan1, F. Wu1, S. Zamir3, J. Salzman3 and J.S. Speck2

1  Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
2  Materials Department, University of California, Santa Barbara, CA 93106, USA
3  Department of Electrical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel

ygolan@bgumail.bgu.ac.il

(Received: 15 August 2002 / Received in final form: 24 November 2002 / Accepted: 19 December 2002 Published online: 25 February 2003 )

Abstract
GaN films were grown using metal-organic chemical vapor deposition (MOCVD) on intentionally roughened c-sapphire in order to study the effect of the substrate roughness. Controlled substrate damage was achieved by exposing the substrate surfaces to controlled amounts of trimethylgallium followed by exposure to hydrogen at elevated temperature. The bulk film quality was studied by high-resolution X-ray diffraction and the surface topography was examined by atomic force microscopy. It was observed that mild substrate roughness (surface pit depth up to 30 nm) does not have a significant effect on the bulk film quality nor the GaN surface topography, and that recovery of the surface roughness is observed in very early stages of film growth. Cross sectional transmission electron microscopy confirmed that MOCVD GaN grown on inclined sidewalls etched in c-sapphire maintained the $\{0001\}_{\rm sapphire}\parallel\{0001\}_{\rm GaN}$ epitaxial relationship despite the substrate miscut of  ca. 15° with respect to the c-axis.

PACS
68.35.Ct - Interface structure and roughness.
68.55.Ac - Nucleation and growth: microscopic aspects.

© EDP Sciences 2003


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