AlGaAs/GaAs photovoltaic cells with an array of InGaAs QDs

Specific features of the fabrication of AlGaAs/GaAs single-junction photovoltaic cells with an array of quantum dots (QDs) by molecular beam epitaxy have been studied. It was shown for the first time that, in principle, vertically coupled QDs can be incorporated, with no dislocations formed, into the structure of photovoltaic cells without any noticeable deterioration of the structural quality of the $p$–$n$ junction. Owing to the additional absorption of the long-wavelength part of the solar spectrum in the QD medium and to the subsequent effective separation of photogenerated carriers, a $\sim$1% increase in the short-circuit current density $J_{sc}$ was demonstrated for the first time in the world for photovoltaic cells with QDs. The maximum efficiency of the photovoltaic cells was 18.3% in conversion of the unconcentrated ground level solar spectrum AM1.5G.