Increasing the Photocurrent of a Ga(In)As Subcell in Multijunction Solar Cells Based on GaInP/Ga(In)As/Ge Heterostructure

Abstract

Spectral characteristics of the Ga(In)As subcell of triple-junction GaInP/Ga(In)As/Ge solar cells have been experimentally and theoretically studied. It is established that the use of a wide-bandgap “window” layer with optimum thickness (100 nm for Ga_0.51In_0.49P, 110 nm for Al_0.4Ga_0.6As, and 115 nm for the Al_0.8Ga_0.2As) in Ga(In)As subcell allows the response photocurrent to be increased by about 0.5 mA/cm²; the change of material in the rear potential barrier of the GaInP subcell from Al_0.53In_0.47P to p⁺-Ga_0.51In_0.49P or AlGaAs allows the short-circuit current of Ga(In)As subcell to be additionally increased by about 0.8 mA/cm²; and the use of a wide-bandgap n⁺⁺-Ga_0.51In_0.49P layer instead of n⁺⁺-GaAs in the tunnel diode increases the photocurrent by about 1 mA/cm².