Temperature dependence of photoconductivity in polycrystalline semiconductors

Abstract The photoconductivity σ in polycrystalline semiconductors, which arises from a modulation by optical illumination of the grain boundary diffusion potentials and the effect of these potentials on the majority carrier current, exhibits a pronounced temperature dependence. Calculations of photoconductivity versus temperature (100 – 400 K) for polycrystalline silicon indicate that there exists a threshold photogeneration rate G ph (1) above which photoconductivity increases rapidly with G ph and that G ph (1) increases with temperature and decreases with grain size d . It is further observed that σ ≃ G ph d 2 , i.e. σ is independent of T , at sufficiently large photogeneration rates. These results provide a basis for the extraction of parameters, such as grain size and grain boundary interface state density, from measurements of the temperature and photogeneration rate dependence of photoconductivity of polycrystalline semiconductors.