ELECTRICAL-PROPERTIES OF POLYCRYSTALLINE SILICON IN THE DARK AND UNDER ILLUMINATION

The electrical resistivity and mobility of polycrystalline silicon are computed in the temperature range 100 to 500 K in dark and under illumination using a carrier trapping model. Computations show that a) there are three regions where with decreasing temperature, the dark resistivity first decreases slightly, then increases (exponentially), and finally saturates at low temperatures, b) the diffusion potential at the grain boundaries is reduced appreciably under illumination, and c) the resistivity under illumination decreases at all temperatures from its dark value for low levels of illumination whereas it saturates if the level of illumination is raised. The predicted results are found to agree reasonably with known experimental findings.