The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Philip Dawson, S Schulz, R. A. Oliver, M. J. Kappers, C. J. Humphreys

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    Abstract

    In this paper, we compare and contrast the experimental data and the theoretical predictions of the low temperature optical properties of polar and nonpolar InGaN/GaN quantum well structures. In both types of structure, the optical properties at low temperatures are governed by the effects of carrier localisation. In polar structures, the effect of the in-built electric field leads to electrons being mainly localised at well width fluctuations, whereas holes are localised at regions within the quantum wells, where the random In distribution leads to local minima in potential energy. This leads to a system of independently localised electrons and holes. In nonpolar quantum wells, the nature of the hole localisation is essentially the same as the polar case but the electrons are now coulombically bound to the holes forming localised excitons. These localisation mechanisms are compatible with the large photoluminescence linewidths of the polar and nonpolar quantum wells as well as the different time scales and form of the radiative recombination decay curves.
    Original languageEnglish
    Article number181505
    JournalJournal of Applied Physics
    Volume119
    DOIs
    Publication statusPublished - 5 May 2016

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