Nonlinear and dynamic properties of charge transport in polycrystalline silicon under optical illumination

Nonlinear and dynamic properties of the photocurrent in polycrystalline silicon (polysilicon) are studied theoretically. The admittance of the photoexcited polysilicon is calculated as a function of frequency, DC bias, and illumination level. Application of the theory to the spectroscopy of interface states at grain boundaries is considered. The possibility of determining the recombination current density at grain boundaries by measuring the nonlinear photocurrent and photoadmittance is demonstrated.