Light-beam-induced current analysis for preferentially doped polysilicon solar cells

Light-beam-induced current in large-grained polysilicon solar ceils with preferential doping along grain boundaries is analyzed in two dimensions. The Green's function method is used in solving the minority-carrier diffusion equation. The resulting short-circuit currents per unit bandwidth when the light beam is centered over either a grain boundary or the adjacent grain volume are used to calculate the photoresponse enhancement due to the preferential-doping effect. The calculation results are fitted to experimental data obtained by others and good agreement is obtained. The dependence of photoresponse on preferential doping penetration depth and cell thickness is also analyzed or order to determine the conditions under which the preferential doping becomes effective in augmenting cell current.