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Atom probe reveals the structure of In x Ga 1– x N based quantum wells in three dimensions
Author(s) -
Galtrey M. J.,
Oliver R. A.,
Kappers M. J.,
McAleese C.,
Zhu D.,
Humphreys C. J.,
Clifton P. H.,
Larsen D.,
Cerezo A.
Publication year - 2008
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200778595
Subject(s) - indium , atom probe , quantum well , atom (system on chip) , monolayer , analytical chemistry (journal) , alloy , classification of discontinuities , nanometre , chemistry , materials science , physics , nanotechnology , optoelectronics , optics , metallurgy , mathematical analysis , laser , mathematics , chromatography , computer science , composite material , embedded system
Abstract The three‐dimensional atom probe has been used to characterize In x Ga 1– x N based multiple quantum well structures emitting from the green to the ultra‐violet with sub‐nanometre resolution over a 100 nm field of view. The results show gross discontinuities and compositional variations within the UV‐emitting quantum well layers on a 20–100 nm length scale. We propose that these may contribute to the high efficiency of this structure. In addition, the analysis shows the presence of indium in the barrier layers of all the samples, whether or not there was an indium precursor present during barrier growth. The distribution of indium within the blue‐ and green‐emitting In x Ga 1– x N quantum wells is also analyzed, and we find no evidence that In x Ga 1– x N with a range of compositions is not a random alloy, and so rule out indium clustering as the cause of the reported carrier localization in these structures. The upper interface of each quantum well layer is shown to be rougher and more diffuse than the lower, and the existence of monolayer steps in the interfaces that could effectively localize carriers at room temperature is revealed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)