Impact of alloyed capping layers on the performance of In As quantum dot solar cells

Utrilla Lomas, Antonio David and Ulloa Herrero, José María and Gacevic, Zarko and Reyes, D.F. and Artacho Huertas, Irene and Ben, T. and González, D. and Hierro Cano, Adrián and Guzmán Fernández-González, Álvaro de (2016). Impact of alloyed capping layers on the performance of In As quantum dot solar cells. "Solar Energy Materials And Solar Cells", v. 144 ; pp. 128-135. ISSN 0927-0248. https://doi.org/10.1016/j.solmat.2015.08.009.

Description

Title: Impact of alloyed capping layers on the performance of In As quantum dot solar cells
Author/s:
  • Utrilla Lomas, Antonio David
  • Ulloa Herrero, José María
  • Gacevic, Zarko
  • Reyes, D.F.
  • Artacho Huertas, Irene
  • Ben, T.
  • González, D.
  • Hierro Cano, Adrián
  • Guzmán Fernández-González, Álvaro de
Item Type: Article
Título de Revista/Publicación: Solar Energy Materials And Solar Cells
Date: January 2016
ISSN: 0927-0248
Volume: 144
Subjects:
Freetext Keywords: Solar cells, Quantum dots, Quantum Wells, Type-II, Carrier transport, Electron trapping
Faculty: E.T.S.I. Telecomunicación (UPM)
Department: Electrónica Física
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

The impact of using thin GaAs(Sb)(N) capping layers (CLs) on InAs/GaAs quantum dots (QDs) is investigated for their application in solar cell devices. We demonstrate the ability to combine strain-balancing techniques with band engineering approaches through the application of such CLs. Extended photo-response is attainable by means of an independent tunability of the electron and hole confinements in the QD. Moreover, the CL acts itself as a quantum well (QW), providing an additional photoresponse, so that the devices work as hybrid QD-QW solar cells. The use of a GaAsSb CL is particularly beneficial, providing devices with efficiencies under AM1.5 conditions 20% higher than standard GaAs-capped QDs. This is mainly due to a significant increase in photocurrent beyond the GaAs bandgap, leading to an enhanced short-circuit current density (J(sc)). The addition of N to the CLs, however, produces a strong reduction in J(sc). This is found to be related to carrier collection problems, namely, hindered electron extraction and retrapping in the CLs. Nevertheless, the application of reverse biases induces a release of the trapped carriers assisted by a sequential tunneling mechanism. In the case of GaAsN CLs, this leads to a complete carrier collection and reveals an even higher QD-QW-related photocurrent than when using a GaAsSb CL. The hindered carrier collection is stronger in the case of the quaternary CLs, likely due to the faster recombination rates in the type-I GaAsSbN/GaAs QW structure as compared to the type-II ternary counterparts. Nevertheless, alternative approaches, such as the use of a thinner CL or a short-period superlattice CL, lead to significant improvements, demonstrating a great potential for the quaternary CLs under a proper device design.

Funding Projects

TypeCodeAcronymLeaderTitle
Government of SpainMAT2013-47102-C2-2-RUnspecifiedUnspecifiedUnspecified
Government of SpainMAT2010-15206UnspecifiedUnspecifiedUnspecified

More information

Item ID: 45993
DC Identifier: http://oa.upm.es/45993/
OAI Identifier: oai:oa.upm.es:45993
DOI: 10.1016/j.solmat.2015.08.009
Official URL: http://www.sciencedirect.com/science/article/pii/S0927024815003967
Deposited by: Memoria Investigacion
Deposited on: 23 May 2017 16:56
Last Modified: 31 Jan 2018 23:30
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