Title: Homoepitaxy on GaN substrate with various treatments by metalorganic vapor phase epitaxy
Authors: Chen, Kuei-Ming
Wu, Yin-Hao
Yeh, Yen-Hsien
Chiang, Chen-Hao
Chen, Kuei-You
Lee, Wei-I.
Department of Electrophysics
Keywords: Homoepitaxy;Metalorganic vapor phase epitaxy;Nitrides;Gallium nitride
Issue Date: 1-Mar-2011
Abstract: This study shows the morphological, optical, and crystal characteristics of homoepitaxial GaN epilayers that were overgrown by metalorganic vapor phase epitaxy (MOVPE) on the Ga-polar face of GaN substrates that had undergone various surface treatments. The MOVPE overgrown epilayer with surface treatment was fine polished (sample C) to obtain a flat surface that exhibits two-dimensional step-flow growth. And the interface between the MOVPE overgrown epilayer and the GaN substrate was completely absent, indicating the continuous growth of GaN, and, correspondingly, the high degree of homoepitaxy. However, a network of cracks appeared in as-grown sample A (mechanically polished) and hillocks formed with the striped morphology in as-grown sample B (ICP treated). The dislocation density and full width at half maximum (FWHM) obtained by X-ray measurements of as-grown sample C were superior to those obtained by other surface treatments and the original GaN substrate. According to the photoluminescence (PL) and cathodoluminescence (CL) measurements, the decreasing FWHM of band edge emission (NBE) of the overgrown epilayers was attributable to the point defects of V(N) being greatly reduced. Additionally, cross-sectional transmission electron microscopy (TEM) revealed that many threading dislocations formed in sample A by edge type dislocations and intermittently appeared due to inter-crack. (C) 2010 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.jcrysgro.2010.10.018
ISSN: 0022-0248
DOI: 10.1016/j.jcrysgro.2010.10.018
Volume: 318
Issue: 1
Begin Page: 454
End Page: 459
Appears in Collections:Conferences Paper

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