Lifetime and effective surface recombination velocity measurements in high-efficiency Si solar cells

A conventional analysis method, based on minority carrier diffusion in a solar cell base, is used to obtain bulk lifetime (τ) and effective back-surface recombination velocity (S) from measurements of asymptotic decay times of short-circuit current and open circuit voltage. Since the decay times depend individually on both S and τ, it is necessary to use both current and voltage data for unique results. Experimental measurements of current and voltage transients are presented from variable base resistivity cells, γ-irradiated cells and cells with intentionally damaged back surface field regions. These cells exhibit lifetimes from one to several hundred µsec and recombination velocities from 100 to 5000 cm/sec. All features of the data are accounted for by the analysis.