Nowadays, LPCVD (Low Pressure Chemical Vapor Deposition) and highly doped polycrystalline silicon films have numerous applications in microelectronic component manufacturing technologies, integrated circuits and solar cells. The complexity of the circuits, and the increasing degree of integration of the components, constantly require improvement and mastery of the properties of this type of material. As part of this work, we are interested in the study of the effect of doping and annealing Effect on grain boundary width of polycrystalline silicon thin films deposited by LPCVD. The results obtained showed, on the one hand, that arsenic doped layers are more resistive than boron doped ones, and on the other hand, and that the diffusion of dopants is generally much greater in grain boundaries than in grains; and considering the importance of the average grain size in the polycrystalline silicon material, which is an important parameter, on which the physical and electrical properties of this material depend.