GaAs/Si tandem solar cell using epitaxial lift-off technique

The transplantation of GaAs solar cell from GaAs substrate to Si substrate without degrading the conversion efficiency is possible. The crystal quality of the transplanted GaAs film on Si substrate is comparable to that grown on GaAs substrate and much higher than that grown on Si substrate by heteroepitaxy. The conversion efficiencies of GaAs solar cell bonded to Si substrate and homoepitaxial GaAs solar cell without antireflection coating are 13.7% and 14.1% (AM0, 1 sun), respectively. The GaAs/Si tandem solar cell with the efficiency of 19.4% (top cell: 18.2%, bottom cell: 1.2%) has been demonstrated.