Polarized Raman scattering studies of nonpolar a -plane GaN films grown on r -plane sapphire substrates by MOCVD

• Published in: Physica status solidi. A, Applications and materials science Vol. 203; no. 15; pp. 3788 - 3792
• Main Authors: Gao, Haiyong, Yan, Fawang, Li, Jinmin, Wang, Junxi, Yan, Jianchang
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.12.2006; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: 78.30.Fs; 78.30.−j; 81.15.Gh; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Iii-v semiconductors; Lattice dynamics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Phonons in low-dimensional structures and small particles; Physics; Thin films; CVD; Raman spectra; Anisotropy; Temperature effects; Gallium nitrides; Backscattering; Low pressure; Strained layer; Phonon mode; Stress effects; MOCVD
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.200622306

Nonpolar (11$ \bar 2 $0) a ‐plane GaN thin films were grown on r ‐plane (1$ \bar 1 $02) sapphire substrates by low‐pressure metal organic chemical vapor deposition (MOCVD). The stress characteristics of the a ‐plane GaN films were investigated by means of polarized Raman scattering spectra in backscattering configurations. The experimental results show that there are strong anisotropic in‐plane stresses within the epitaxial a ‐plane GaN films by calculating the corresponding stress tensors. The temperature dependence of Raman scattering spectra was studied in the range from 100 K to 550 K. The measurements reveal that the Raman phonon frequencies decrease with increasing temperature. The temperature at which nonpolar a ‐plane GaN films are strain free is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)