Modelling of GaAsP/InGaAs/GaAs strain-balanced multiple-quantum well solar cells

Abstract

A model of strain balanced quantum well solar cells is presented, together with a high efficiency design for a GaAsP/InGaAs/GaAs device. The effect of tensile and compressive strain on bandstructure is considered in order to compute the electron and hole dispersion relation E(k) in conduction and valence bands. The optical transitions in quantum well and barrier are evaluated and the quantum efficiency, dark current and the photocurrent calculated. Experimental data quantum efficiency and dark current are compared with theoretical calculations in the presence of strain, showing a good agreement. The resulting model is initially applied to a GaAsP/InGaAs/GaAs solar cell and the structure optimised to yield the greatest output power. The model is also applied to the problem of determining the highest efficiencies achievable for quantum well solar cells as a function of strain and confirms the high efficiency potential of strained quantum well solar cells.