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Direct evidence for strain inhomogeneity in inxGa1-xN epilayers by raman spectroscopy

Correia, M.R. and Pereira, S.M.D.S. and Ferreira Pereira Lopes, E.M. and Frandon, J. and Watson, I.M. and Liu, C. and Alves, E. and Sequeira, A.D. and Franco, N. (2004) Direct evidence for strain inhomogeneity in inxGa1-xN epilayers by raman spectroscopy. Applied Physics Letters, 85 (12). pp. 2235-2237. ISSN 0003-6951

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Abstract

This contribution is focused on Raman analysis of the InxGa1-xN alloy. It presents direct evidence that both strain and composition effects must be taken into account to interpret the Raman experimental results. Raman studies have been commonly discussed in view of composition inhomogeneity only, neglecting the possible existence of strain depth variations, recently shown to occur for layers grown above the critical layer thickness. The effects of this variation on the A1(LO) phonon frequency could only be investigated by combining both structural and Raman measurements. In this letter, a set of InxGa1-xN layers has been chemically etched during different periods, allowing the depth variation of the phonon frequency to be unambiguously evidenced. Comparing the Raman spectra before and after etching, two distinct InxGa1-xN regions, differing on their strain state, are identified: a relaxed one, found near the surface region; another one, grown coherently (i.e., pseudomorphic) to the GaN buffer layer. These results are in excellent agreement with an additional reciprocal space map analysis.

Item type: Article
ID code: 37920
Keywords: inxGa1-xN epilayers , raman spectroscopy, surface cleaning, crystal structures, Physics
Subjects: Science > Physics
Department: Faculty of Science > Physics
Strathclyde Business School > Accounting and Finance
Faculty of Science > Institute of Photonics
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 27 Feb 2012 14:13
    Last modified: 16 Jul 2013 21:37
    URI: http://strathprints.strath.ac.uk/id/eprint/37920

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