Wagener, M. C. and Carrington, P. J. and Botha, J. R. and Krier, A. (2014) Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings. Journal of Applied Physics, 116 (4): 044304. ISSN 0021-8979
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Abstract
The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudomonochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo-and thermal-emission characteristics of the quantum rings. (C) 2014 AIP Publishing LLC.