Effects of intergranular barrier fluctuations on the electrical conductivity of polycrystalline semiconductors

We studied the influence of intergranular barrier fluctuations on the electrical response of 3D semiconductor polycrystals. We first computed with a numerical simulation model the dispersion in the intergranular barrier height on polycrystalline tin oxide due to the punctual character of the donors. Then, in order to quantify the effects of the barrier fluctuation in the overall conductivity of the semiconductor, we added the dispersion to the well known brick-layer model and determined the connection between impedance measurements and grain boundary resistivity. We found that, the brick-layer model gives lower values for the real intergrain resistivity. However, the error can be quantified indicating that the brick-layer model is not a bad approximation to determine electrical properties of intergrains of a polycrystal, specially for relatively large grains. •We determined the intergranular barrier height on polycrystalline tin oxide due to the punctual character of the donors.•We studied the effect of inter-granular barrier fluctuations on the resistivity for a cubic network.•We found that only for small intergrain sizes the brick-layer model with and without dispersion differ appreciably.