Effect of GaAs Step Layer Thickness in InGaAs/GaAsP Stepped Quantum-Well Solar Cell

A multiple-stepped quantum-well (MSQW) solar cell, in which GaAs step layers are sandwiched between strain-balanced InGaAs wells and GaAsP barriers, has been proposed, and the improved sub-GaAs-bandgap quantum efficiency has been demonstrated. The optical properties of MSQW solar cells with different GaAs step layer thickness are investigated. The recombination losses inside the QWs have been studied by bias-dependent photoluminescence. The recombination losses decrease with increasing the GaAs step layer thickness. Controlling the GaAs step layer thickness is a feasible way to increase short-circuit current without largely degrading open-circuit voltage.