Investigations of phonon sidebands in InGaN/GaN multi-quantum well luminescence

Pecharroman-Gallego, R. and Edwards, P.R. and Martin, R.W. and Watson, I.M. (2002) Investigations of phonon sidebands in InGaN/GaN multi-quantum well luminescence. Materials Science and Engineering B, 93 (1-3). pp. 94-97. ISSN 0921-5107 (http://dx.doi.org/10.1016/S0921-5107(02)00024-7)

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Abstract

Analysis of the phonon sidebands (PSB) observed in the photoluminescence (PL) spectra from a series of InGaN/GaN multi-quantum wells is described. The structures are grown by metal organic vapour phase epitaxy (MOVPE) on sapphire substrates and cover a range of emission wavelengths (390-600 nm) and number of quantum wells (from 1 to 10). Up to four phonon satellites are observed in the side-band of the quantum well luminescence, with an energy separation similar to the GaN LO-phonon energy (90 meV). The relative intensity and spectral properties of these satellites have been investigated as a function of the peak energy of the luminescence, sample temperature and the number of wells. Huang-Rhys parameters in the range 0.1-0.6 are observed. Analysis of the shape of the PSBs from the single quantum wells (SQWs) indicate that a significant fraction (40%) of the excitons are strongly localised. This fraction shows some increase for samples emitting at longer wavelengths. The relative strength of the first phonon satellite, compared with the no-phonon peak, is observed to increase with temperature and decrease with the number of periods in the multi-quantum well structures