Resolution of discrete excited states in InxGa1-xN multiple quantum wells using degenerate four-wave mixing

Dmytro O. Kundys, J.-P. R. Wells, A. D. Andreev, S. A. Hashemizadeh, T. Wang, P. J. Parbrook, A. M. Fox, D. J. Mowbray, M. S. Skolnick

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We report on two pulse, degenerate four-wave mixing (DFWM) measurements on shallow InxGa1-xN/GaN multiquantum wells (MQWs) grown on sapphire substrates. These reveal pulse length limited signal decays. We have found a 10:1 resonant enhancement of the DFWM signal at the excitonic transition frequencies which thereby give a sharp discrimination of the discrete excitonic contributions within the featureless distribution seen in absorption spectra. The exciton resonances have peak positions, which yield good overall agreement with a full k(.)p model calculation for the quantum well (QW) energy levels and optical transition matrix elements. InxGa1-xN/GaN MQWs generally exhibit strongly inhomogeneously broadened excitation spectra due to indium fluctuation effects; this approach therefore affords a practical method to extract information on the excited excitonic states not available previously.

Original languageEnglish
Article number165309
JournalPhysical Review B: Condensed Matter and Materials Physics
Issue number16
Publication statusPublished - 11 Apr 2006


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