Anisotropic Emission in Strain-Balanced Quantum Well Solar Cells

Abstract:

Strain-balanced quantum well solar cells (SB-QWSC) extend the photon absorption edge beyond that of bulk GaAs by incorporation of quantum wells in the i-region of a pin device. The strain-balanced quantum well solar cell benefits from a fundamental efficiency enhancement due to anisotropic emission from the quantum wells. This anisotropy arises from a splitting of the valence band due to compressive strain in the quantum wells, suppressing a transition which contributes to emission from the edge of the quantum wells. We have studied both the emission light polarized in the plane perpendicular (TM) to the quantum well which couples exclusively to the light hole transition and the emission polarized in the plane of the quantum wells (TE) which couples mainly to the heavy hole transition. It was found that the spontaneous emission rates TM and TE increase when the quantum wells are deeper. We have also demonstrated that the photo-generated carriers can escape from the QWs with near unity efficiency, via a thermally-assisted tunneling process, because gain is several orders greater than radiative recombination.

• Periodical: Advanced Materials Research (Volume 976)
• Pages: 235-239
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.976.235
• Online since: June 2014
• Authors: C. Ivan Cabrera, J.C. Rimada, Luis Hernandez, Agustin Enciso, David Armando Contreras-Solorio*
• Keywords: Fundamentals, III-V Semiconductors, Quantum Well

References

[1] D.C. Johnson, I. Ballard, K.W.J. Barnham, M. Mazzer, T.N.D. Tibbits, J. Roberts, G. Hill, and C. Calder, in: Proceedings of the 4th World Conference on Photovoltaic Energy Conversion, Hawaii, 7–12 May 2006 (IEEE, 2006), p.26–31.

DOI: 10.1109/wcpec.2006.279338

[2] N.J. Ekins-Daukes, J.M. Barnes, K.W.J. Barnham, J.P. Connolly, M. Mazzer, J.C. Clark, R. Grey, G. Hill, M.A. Pate, and J.S. Roberts: Sol. Energy Mater. Sol. Cells, 68 (2001)71.

[3] J.G.J. Adams, B.C. Browne, I.M. Ballard, J.P. Connolly, N. L A. Chan, A. Ioannides, W. Elder, P.N. Stavrinou, K.W.J. Barnham and N.J. Ekins-Daukes: Recent results for single junction and tandem quantum well solar cells. Presented at 25th European Photovoltaic Solar Energy Conference and 5th World Conference on Photovoltaic Energy Conversion, Spain, (2010).

DOI: 10.1002/pip.1069

[4] J.G.J. Adams, W. Elder, P.N. Stavrinou, J.S. Roberts, M. Gonzalez, J.G. Tischler, R.J. Walters, J. Abell, I. Vurgaftman, J. Meyer, P. Jenkins, K.W.J. Barnham, N.J. Ekins-Daukes: Experimental measurement of restricted radiative emission in quantum well solar cells. Proceedings of the 35th IEEE Photovoltaic Specialists' Conference, (2010).

DOI: 10.1109/pvsc.2010.5614119

[5] C.I. Cabrera, J.C. Rimada, J.P. Connolly and L. Hernández: J. Appl. Phys. 113 (2013) 024512.

[6] J. Singh: Electronic and Optoelectronic Properties of Semiconductor Structures, Cambridge University Press, (2003).

[7] E. Tsui, J. Nelson, K.W.J. Barnham, C. Button, and J.S. Roberts: J. Appl. Phys. 80 (1996) 4599.

[8] Information on http: /www. astm. orgi.

[9] M. Courel, J.C. Rimada, L. Hernández: J. Appl. Phys. 112 (2012) 054511.