Diffusion length determination in <i>p</i>-<i>n</i> junction diodes and solar cells

Abstract

An experimental technique for determining the minority carrier diffusion length in the base region of Si p-n junction diodes and solar cells is described. The procedure is to operate the device in the photoconductive mode and to measure its photoresponse in the wavelength region near the energy gap. The ratio of incident light intensity to photocurrent is a linear function of reciprocal absorption coefficient for each wavelength; the slope of the set of points directly yields the diffusion length. In addition, a nonlinear least-squares analysis is also used to determine the diffusion length.