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Quantum-dot-induced optical transition enhancement in InAs quantum-dot-embedded p-i-n GaAs solar cells
KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
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2011 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, no 11, 113514- p.Article in journal (Refereed) Published
Abstract [en]

Photocurrents (PCs) of three p-i-n GaAs solar cells, sample A with InAs quantum dots (QDs) embedded in the depletion region, B with QDs in the n region, and C without QDs, were studied experimentally and theoretically. Above GaAs bandgap, the PC of A is increased, while B is decreased with respect to C, since in A, the QD-induced reflection of hole wave function increases its overlap with electron wave function so that the optical transition rate is enhanced, while carrier mobility in B is reduced due to QD-induced potential variations. Moreover, A and B have increased PCs in the sub-GaAs-bandgap range due to QD optical absorptions.

Place, publisher, year, edition, pages
2011. Vol. 99, no 11, 113514- p.
Keyword [en]
Well Infrared Photodetector, Photocurrent, Efficiency
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-42371DOI: 10.1063/1.3638488ISI: 000295034400089Scopus ID: 2-s2.0-80053190661OAI: oai:DiVA.org:kth-42371DiVA: diva2:446959
Note
QC 20111010Available from: 2011-10-10 Created: 2011-10-10 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Study of quantum dots on solar energy applications
Open this publication in new window or tab >>Study of quantum dots on solar energy applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis studies p-i-n GaAs solar cells with self-assembled InAs quantum dots (QDs) inserted. The values of this work lie in three aspects. First, by comparing the cell performance with QDs in the i-region and the n-region, the photocurrent (PC) production from QDs by thermal activation and/or intermediate band (IB) absorption is proved to be much lower in efficiency than tunneling. Second, the efficiency of PC production from QDs, characterized by PC spectrum, is helpful to design QD-based photodetectors. Third, closely spaced InAs QD layers allow a strong inter-layer tunneling, leading to an effective PC production from QD deep states, potential for solar cell application. Fourth, from the temperature-dependent PC spectra the minority photohole thermal escape is found to be dominant on PC production from QDs in the n-region. The thermal activation energy reflects the potential variations formed by electron filling in QDs.

Apart from InAs QDs, this thesis also explores the blinking correlation between two colloidal CdSe QDs. For QD distance of 1 µm or less, there is a bunched correlation at delay τ = 0, meaning that the two QDs blink synchronously. Such correlation disappears gradually as QD distance increases. The correlation is possibly caused by the stimulated emission between the two nearby QDs.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xii, 60 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2012:12
Keyword
Epitaxial InAs quantum dot solar cell
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-94021 (URN)978-91-7501-352-7 (ISBN)
Public defence
2012-06-04, FA32, AlbaNova Universitetscentrum, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
QC 20120507Available from: 2012-05-07 Created: 2012-05-04 Last updated: 2012-05-07Bibliographically approved

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