A study of the optical and polarisation properties of InGaN/GaN multiple quantum wells grown on a-plane and m-plane GaN substrates

Dmytro Kundys, Danny Sutherland, Matthew J. Davies, Fabrice Oehler, James Griffiths, Phil Dawson, Menno J. Kappers, Colin J. Humphreys, Stefan Schulz, Fengzai Tang, Rachel A. Oliver

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Abstract

We report on a comparative study of the low temperature emission and polarisation properties of InGaN/GaN quantum wells (QWs) grown on nonpolar a-plane and m-plane free-standing bulk GaN substrates where the In content varied from 0.14 to 0.28 in the m-plane series and 0.08 to 0.21 for the a-plane series. The low temperature photoluminescence spectra from both sets of samples are very broad with full width at half-maximum height increasing from 81 to 330 meV as the In fraction increases. Comparative photoluminescence excitation spectroscopy indicates that the recombination mainly involves strongly localised carriers. At a temperature of 10 K the degree of linear polarisation of the a-plane samples is much smaller than of the m-plane counterparts and also varies across the spectrum. From polarisation-resolved photoluminescence excitation spectroscopy we measured the energy splitting between the lowest valence sub-band states to lie in the range of 23-54 meV for both a-and m-plane samples in which we could observe distinct exciton features in the polarised photoluminescence excitation spectroscopy. Thus, the thermal occupation of a higher valence subband cannot be responsible for the reduction of the degree of linear polarisation. Time-resolved spectroscopy indicates that in a-plane samples there is an extra emission component which at least partly responsible for the reduction in the degree of linear polarisation.
Original languageEnglish
Pages (from-to)736-743
Number of pages8
JournalScience and Technology of Advanced Materials
Volume17
Issue number1
DOIs
Publication statusPublished - 10 Nov 2016

Keywords

  • cond-mat.mes-hall
  • physics.optics

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