Type-II GaAsSb/GaAsN superlattice solar cells

A. Gonzalo; A. D. Utrilla; U. Aeberhard; J. M. Llorens; B. Alén; D. Fuertes Marrón; A. Guzman; A. Hierro; J.M. Ulloa

doi:10.1117/12.2290079

16 February 2018 Type-II GaAsSb/GaAsN superlattice solar cells

A. Gonzalo, A. D. Utrilla, U. Aeberhard, J. M. Llorens, B. Alén, D. Fuertes Marrón, A. Guzman, A. Hierro, J.M. Ulloa

Proceedings Volume 10527, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VII; 105270D (2018) https://doi.org/10.1117/12.2290079
Event: SPIE OPTO, 2018, San Francisco, California, United States

Abstract

Dilute nitride GaAsSbN is an ideal candidate to form the 1-1.15 eV lattice-matched sub-cell that would significantly enhance the performance of 3- and 4-junction solar cells. However, growth problems inherent to this quaternary alloy lead typically to a poor crystal quality that limits its applicability. Better compositional control and crystal quality have been recently reported by growing the material as a GaAsSb/GaAsN superlattice, because of the spatial separation of Sb and N that avoid miscibility problems. Moreover, these structures provide bandgap tunability trough period thickness. Here we study the performance of lattice-matched 1.15 eV GaAsSb/GaAsN type-II superlattice p-i-n junction solar cells with different period thickness and compare them with the bulk and GaAsSbN/GaAs type-I superlattice counterparts. We demonstrate carrier lifetime tunability through the period thickness in the type-II structures. However, the long carrier lifetimes achievable with periods thicker than 12 nm are incompatible with a high carrier extraction efficiency under short-circuit conditions. Only superlattices with thinner periods and short carrier lifetimes show good solar cell performance. Quantum kinetic calculations based on the non-equilibrium Green’s function (NEGF) formalism predict a change in transport regime from direct tunneling extraction to sequential tunneling with sizable thermionic emission components when passing from 6 nm to 12 nm period length, which for low carrier lifetime results in a decrease of extraction efficiency by more than 30%.

Citation Download Citation

A. Gonzalo, A. D. Utrilla, U. Aeberhard, J. M. Llorens, B. Alén, D. Fuertes Marrón, A. Guzman, A. Hierro, and J.M. Ulloa "Type-II GaAsSb/GaAsN superlattice solar cells", Proc. SPIE 10527, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VII, 105270D (16 February 2018); https://doi.org/10.1117/12.2290079

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