HIGH-EFFICIENCY AL0.2GA0.8AS SI STACKED TANDEM SOLAR-CELLS USING EPITAXIAL LIFT-OFF/

In this paper, the potential of high conversion efficiency of solar en ergy through the combination of Al0.2Ga0.8As and Si cells is illustrat ed by a mechanically stacked tandem using, for the first time, the epi taxial lift-off (ELO) technique to remove the top cell from its substr ate. The selective etching of the GaAs substrate provides efficient li ght transmission to the bottom cell. Photoluminescence decay experimen ts show that substrate removal also enhances photon recycling effects. The measured efficiency of the Al0.2Ga0.8As/Si tandem reaches 21% AM1 .5.