Diffusion lengths in solar cells from short-circuit current measurements

The minority-carrier diffusion length in the base region of a silicon solar cell has been determined by measuring the short-circuit current as a function of the wavelength of incident light. The incident light intensity required to produce a given short-circuit current is a linear function of the reciprical absorption coefficient for each wavelength, and the extrapolation of this linear relation to zero intensity yields the diffusion length. This method is similar to the surface photovoltage and open-circuit voltage methods; however, the accuracy for high light bias levels appears to be greatly improved.