InGaAs/GaAsP strain-compensated superlattice solar cell for enhanced spectral response

A superlattice solar cell with InGaAs well and GaAsP barrier was realized for the first time. Increase in short-circuit current by 2 mA/cm² was achieved with 60 stacks of the 3.7-nm-thick wells as compared with a GaAs p-i-n reference cell. No degradation of spectral response for the wavelength range of GaAs absorption suggested efficient carrier transport across the wells due to tunneling through the thin barriers. A breakthrough for this achievement was strain management with monolayer-thin GaAs layer at the InGaAs/GaAsP interface, where huge lattice mismatch seems to have induced localized defects and have functioned as recombination centers.