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Polarized Raman scattering studies of nonpolar a ‐plane GaN films grown on r ‐plane sapphire substrates by MOCVD
Author(s) -
Gao Haiyong,
Yan Fawang,
Li Jinmin,
Wang Junxi,
Yan Jianchang
Publication year - 2006
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200622306
Subject(s) - sapphire , metalorganic vapour phase epitaxy , raman spectroscopy , chemical vapor deposition , epitaxy , raman scattering , materials science , scattering , anisotropy , thin film , phonon , analytical chemistry (journal) , condensed matter physics , optoelectronics , optics , chemistry , nanotechnology , laser , physics , layer (electronics) , chromatography
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)