Extended x-ray absorption fine structure studies of InGaN epilayers

Katchkanov, V. and O'Donnell, K.P. and Mosselmans, J.F.W. and Hernandez, S. and Martin, R.W. and Nanishi, Y. and kurochi, M. and Watson, I.M. and van der Stricht, W. and Calleja, E. (2005) Extended x-ray absorption fine structure studies of InGaN epilayers. MRS Online Proceedings Library, 831. pp. 203-207. ISSN 0272-9172

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Abstract

The local structure around In atoms in InGaN epilayers grown by Molecular Beam Epitaxy (MBE) and by Metal-Organic Chemical Vapour Deposition (MOCVD) was studied by means of Extended X-ray Absorption Fine Structure (EXAFS). The averaged In fraction of MOCVD grown samples ranged from 10% to 40% as estimated by Electron Probe Microanalysis (EPMA). The In fraction of MBE grown samples spanned the range from 13% to 96%. The In-N bond length was found to vary slightly with composition, both for MBE and MOCVD grown samples. Moreover, for the same In content, the In-N bond lengths in MOCVD samples were longer than those in MBE grown samples. In contrast, the In-In radial separations in MOCVD and MBE samples were found to be indistinguishable for the same In molar fraction. The In-Ga bond length was observed to deviate from average cation-cation distance predicted by Vegard's law for MBE grown samples which indicates alloy compositional fluctuations.