title: A study of the optical and polarisation properties of InGaN/GaN multiple quantum wells grown ona-plane andm-plane GaN substrates.
abstract: We report on a comparative study of the low temperature emission and polarisation properties of InGaN/GaN quantum wells grown on nonpolar ([Formula: see text])a-plane and ([Formula: see text])m-plane free-standing bulk GaN substrates where the In content varied from 0.14 to 0.28 in them-plane series and 0.08 to 0.21 for thea-plane series. The low temperature photoluminescence spectra from both sets of samples are broad with full width at half maximum height increasing from 81 to 330 meV as the In fraction increases. Photoluminescence excitation spectroscopy indicates that the recombination mainly involves strongly localised carriers. At 10 K the degree of linear polarisation of thea-plane samples is much smaller than of them-plane counterparts and also varies across the spectrum. From polarisation-resolved photoluminescence excitation spectroscopy we measured the energy splitting between the lowest valence sub-bands to lie in the range of 23-54 meV for thea- andm-plane samples in which we could observe distinct exciton features. Thus the thermal occupation of a higher valence sub-band cannot be responsible for the reduction of the degree of linear polarisation at 10 K. Time-resolved spectroscopy indicates that ina-plane samples there is an extra emission component which is at least partly responsible for the reduction in the degree of linear polarisation.
authors.affiliation: School of Physics and Astronomy, Photon Science Institute, University of Manchester , Manchester , UK.
authors.forename: Dmytro
authors.initials: D
authors.lastname: Kundys
authors.affiliation: School of Physics and Astronomy, Photon Science Institute, University of Manchester , Manchester , UK.
authors.forename: Danny
authors.initials: D
authors.lastname: Sutherland
authors.affiliation: School of Physics and Astronomy, Photon Science Institute, University of Manchester , Manchester , UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Davies
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Cambridge , UK.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Oehler
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Cambridge , UK.
authors.forename: James
authors.initials: J
authors.lastname: Griffiths
authors.affiliation: School of Physics and Astronomy, Photon Science Institute, University of Manchester , Manchester , UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Dawson
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Cambridge , UK.
authors.forename: Menno J
authors.initials: MJ
authors.lastname: Kappers
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Cambridge , UK.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Humphreys
authors.affiliation: Photonics Theory Group, Tyndall National Institute , Cork , Ireland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulz
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Cambridge , UK.
authors.forename: Fengzai
authors.initials: F
authors.lastname: Tang
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , Cambridge , UK.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Oliver
keywords: 105 Low-Dimension (1D/2D) materials; 201 Electronics/Semiconductor/TCOs; 204 Optics/Optical applications; 40 Optical; InGaN; magnetic and electronic device materials; non-polar; polarised light; quantum wells