Defects in dilute nitride solar cells

Defects in crystal lattice can influence remarkably performance of semiconductor devices. Such parameters as background doping and nonradiative recombination rate are widely caused by defects. High-quality material with low defect densities is in key-role when fabricating high-efficiency multijunction III-V semiconductor solar cells. GaInNAs(Sb) is a promising material for high-efficiency multijunction solar cells. Well over 40% conversion efficiencies have been demonstrated from molecular-beam-epitaxy grown three-junction solar cell with GaInNAsSb bottom junction [1]. However, relatively low growth temperatures and incorporation of N induces defects to
the material, reducing its current and voltage generation [2]. Therefore, detailed
knowledge about defects and their formation is essential when fabricating high-quality GaInNAs(Sb). We used capacitance spectroscopy to characterize defects in dilute nitride and antimonide materials. Defects and their influence on solar cell operation are discussed.



[1] P.B. J. Allen, V. Sabnis, M. Wiemer and H. Yuen, "44%-efficiency triple-junction solar cells," in 9th International Conference on Concentrator Photovoltaic Systems, Miyazaki, Japan, 2013.
[2] A. Aho, V. Polojärvi, V. Korpijärvi, J. Salmi, A. Tukiainen, P. Laukkanen and M. Guina, "Composition dependent growth dynamics in molecular beam epitaxy of GaInNAs solar cells," Solar Energy Mater. Solar Cells, vol. 124, pp. 150-158, 2014.