A multiple stepped quantum well structure, in which GaAs step layers were sandwiched between strain-balanced InGaAs wells and GaAsP barriers, was proposed and improvements in sub-GaAs-bandgap quantum well were demonstrated. A study was made of the effect of indium diffusion upon the optical properties in quantum well solar cells by measuring the absorption and photoluminescence spectra. Theoretical calculations indicated that the transition energy level and the absorption magnitude were sensitive to indium diffusion. The multiple stepped quantum well structure with GaAs step layer was a feasible way to suppress indium diffusion and enhance the absorption.

Suppressed Indium Diffusion and Enhanced Absorption in InGaAs/GaAsP Stepped Quantum Well Solar Cell. Y.Wen, Y.Wang, Y.Nakano: Applied Physics Letters, 2012, 100[5], 053902