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Proceedings Paper

Type II GaSb/GaAs quantum rings with extended photoresponse for efficient solar cells
Author(s): P. J. Carrington; D. Montesdeoca; H. Fujita; J. James; M. C. Wagener; J. R. Botha; A. R. J. Marshall; A. Krier
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Paper Abstract

The introduction of GaSb quantum dots (QDs) within a GaAs single junction solar cell is attracting increasing interest as a means of absorbing long wavelength photons to extend the photoresponse and increase the short-circuit current. The band alignment in this system is type-II, such that holes are localized within the GaSb QDs but there is no electron confinement. Compared to InAs QDs this produces a red-shift of the photoresponse which could increase the short-circuit current and improve carrier extraction. GaSb nanostructures grown by molecular beam epitaxy (MBE) tend to preferentially form quantum rings (QRs) which are less strained and contain fewer defects than the GaSb QDs, which means that they are more suitable for dense stacking in the active region of a solar cell to reduce the accumulation of internal strain and enhance light absorption. Here, we report the growth and fabrication of GaAs based p-i-n solar cells containing ten layers of GaSb QRs. They show extended long wavelength photoresponse into the near-IR up to 1400 nm and enhanced short-circuit current compared to the GaAs control cell due to absorption of low energy photons. Although enhancement of the short-circuit current was observed, the thermionic emission of holes was found to be insufficient for ideal operation at room temperature.

Paper Details

Date Published: 23 September 2016
PDF: 7 pages
Proc. SPIE 9937, Next Generation Technologies for Solar Energy Conversion VII, 993708 (23 September 2016); doi: 10.1117/12.2236957
Show Author Affiliations
P. J. Carrington, Lancaster Univ. (United Kingdom)
D. Montesdeoca, Lancaster Univ. (United Kingdom)
H. Fujita, Asahi Kasei Corp. (Japan)
J. James, Lancaster Univ. (United Kingdom)
M. C. Wagener, Nelson Mandela Metropolitan Univ. (South Africa)
J. R. Botha, Nelson Mandela Metropolitan Univ. (South Africa)
A. R. J. Marshall, Lancaster Univ. (United Kingdom)
A. Krier, Lancaster Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 9937:
Next Generation Technologies for Solar Energy Conversion VII
Oleg V. Sulima; Gavin Conibeer, Editor(s)

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