Electro-optical properties of InAs and In0.8Ga0.2As quantum dots in GaAs solar cells

Abstract

In the work, GaAs solar cells (SCs) structures with embedded InAs and Ina8Gaa2As arrays of quantum dots (QDs) was obtained by metalorganic vapor-phase epitaxy. The spectral characteristic of internal quantum yield of grown SCs were measured and it was shown that the use of InGaAs QDs allows preserving the quality of the p-n junction even at embedding 20 QD layers, while for InAs QD this index does not exceed 10 QD layers due to earlier defects appearing. The diffusion saturation current values calculated from Voc-Jg dependences were 4 orders of magnitude better for GaAs SCs with In0.8Ga02As QDs that also proved the quality of GaAs p-n junction with such type of QDs. The model for calculating the energy transitions in InGaAs quantum wells was used to characterize two peaks measured in the long-wavelength part of the spectral characteristic of the obtained SCs. It was shown that the peaks observed at 930 and 985 nm corresponds to the energy transitions in the wetting layer and quantum dots, respectively.