Carrier extraction behaviour in type II GaSb/GaAs quantum ring solar cells

Fujita, Hiromi and James Asirvatham, Juanita and Carrington, Peter and Marshall, Andrew and Krier, Anthony and Wagener, Magnus C. and Botha, Johannes Reinhardt (2014) Carrier extraction behaviour in type II GaSb/GaAs quantum ring solar cells. Semiconductor Science and Technology, 29 (3). ISSN 0268-1242

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The introduction of quantum dot (QD) or quantum ring (QR) nanostructures into GaAs single-junction solar cells has shown enhanced photo-response above the GaAs absorption edge, because of sub-bandgap photon absorption. However, to further improve solar cell performance a better understanding of the mechanisms of photogenerated carrier extraction from QDs and QRs is needed. In this work we have used a direct excitation technique to study type II GaSb/GaAs quantum ring solar cells using a 1064 nm infrared laser, which enables us to excite electron-hole pairs directly within the GaSb QRs without exciting the GaAs host material. Temperature and laser intensity dependence of the current-voltage characteristics revealed that the thermionic emission process produced the dominant contribution to the photocurrent and accounts for 98.9% of total photocurrent at 0 V and 300 K. Although the tunnelling process gives only a low contribution to the photocurrent, an enhancement of the tunnelling current was clearly observed when an external electric field was applied.

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Journal Article
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Semiconductor Science and Technology
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05 Aug 2015 08:36
Last Modified:
22 Nov 2022 02:04