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Highly polarized photoluminescence and its dynamics in semipolar (20(2)over-bar(1)over-bar) InGaN/GaN quantum well
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.ORCID iD: 0000-0002-4606-4865
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.ORCID iD: 0000-0002-5007-6893
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2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, no 11, 111113- p.Article in journal (Refereed) Published
Abstract [en]

Very high polarization degree of 0.98, considerably larger than theoretical predictions, has been measured in (20 (2) over bar(1) over bar) In(0.24)Ga(0.7)6N/GaN quantum well by low temperature photoluminescence. With increasing temperature, the polarization degree decreases due to thermal population of the excited valence band level. This effect suggests an accurate method to determine the interlevel energy, which, for the studied well, is 32 meV. Time-resolved photoluminescence measurements set radiative recombination times between 2 and 12 ns for temperatures from 3 to 300 K. Nonradiative recombination was found to be slow, over 2 ns at 300 K, taking place via traps with activation energy of 0.19 eV.

Place, publisher, year, edition, pages
2014. Vol. 104, no 11, 111113- p.
Keyword [en]
Increasing temperatures, InGaN/GaN quantum well, Low temperature photoluminescence, Non-radiative recombinations, Polarization degree, Polarized photoluminescence, Radiative recombination, Time-resolved photoluminescence
National Category
Other Physics Topics
Identifiers
URN: urn:nbn:se:kth:diva-144947DOI: 10.1063/1.4869459ISI: 000333252300013Scopus ID: 2-s2.0-84897888589OAI: oai:DiVA.org:kth-144947DiVA: diva2:715461
Funder
Swedish Energy Agency, 36652-1Knut and Alice Wallenberg Foundation
Note

QC 20140505

Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2017-12-05Bibliographically approved
In thesis
1. Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations
Open this publication in new window or tab >>Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The modern InGaN technology demonstrates high efficiencies only in the blue spectral region and low current operation modes. The growth of InGaN quantum wells (QWs) on nonbasal crystallographic planes (NBP) has potential to deliver high-power blue and green light emitting diodes and lasers. The emission properties of these QWs are largely determined by the localization of carriers in the minima of spatially inhomogeneous band potential, which affects the recombination dynamics, spectral characteristics of the emission, its optical polarization and carrier transport. Understanding it is crucial for increasing the efficiency of NBP structures to their theoretical limit.

In this thesis, the influence of carrier localization on the critical aspects of light emission has been investigated in semipolar  and nonpolar  InGaN QWs. For this purpose, novel multimode scanning near-field optical microscopy configurations have been developed, allowing mapping of the spectrally-, time-, and polarization-resolved emission.

In the nonpolar QW structures the sub-micrometer band gap fluctuations could be assigned to the selective incorporation of indium on different slopes of the undulations, while in the smoother semipolar QWs – to the nonuniformity of QW growth. The nanoscale band potential fluctuations and the carrier localization were found to increase with increasing indium percentage in the InGaN alloy. In spite to the large depth of the potential minima, the localized valence band states were found to retain properties of the corresponding bands. The reduced carrier transfer between localization sites has been suggested as a reason for the long recombination times in the green-emitting semipolar QWs. Sharp increase of the radiative lifetimes has been assigned to the effect of nanoscale electric fields resulting from nonplanar QW interfaces. Lastly, the ambipolar carrier diffusion has been measured, revealing ~100 nm diffusion length and high anisotropy.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 67 p.
Series
TRITA-FYS, ISSN 0280-316X ; 2017:53
Keyword
InGaN, quantum well, semipolar, nonpolar, near-field microscopy, carrier localization, carrier transport, optical polarization
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-214599 (URN)978-91-7729-505-1 (ISBN)
Public defence
2017-09-29, Hall C, Elektrum 229, Kista, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 36652-1Swedish Research Council, 621-2013- 4096
Note

QC 20170919

Available from: 2017-09-19 Created: 2017-09-18 Last updated: 2017-09-19Bibliographically approved

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Marcinkevicius, Saulius

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