Increasing the photocurrent of a Ga(In)As subcell in multijunction solar cells based on GaInP/Ga(In)As/Ge heterostructure

An experimental and theoretical study of the spectral characteristics of the Ga(In)As subcell of the GaInP/Ga(In)As/Ge triple-junction solar cells has been carried out. It is shown that the use of a wide-gap “window” layer with an optimized thickness (Ga$_{0.51}$In$_{0.49}$P – 100 nm, Al$_{0.4}$Ga$_{0.6}$As – 110 nm, Al$_{0.8}$Ga$_{0.2}$As – 115 nm) for the Ga(In)As subcell allows increasing its photocurrent by about 0.5 mA/cm$^2$, replacing the material of the back potential barrier of the GaInP subcell from Al$_{0.53}$In$_{0.47}$P to $p^{+}$-Ga$_{0.51}$In$_{0.49}$P or AlGaAs allows increasing the short circuit current of Ga(In)As subcell by about 0.8 mA/cm$^2$, and the use of the wide-bandgap $n^{++}$-Ga$_{0.51}$In$_{0.49}$P-layer in the tunnel diode instead of $n^{++}$-GaAs increases the photocurrent by about 1 mA/cm$^2$.