Annotation: The paper discusses perspectives of elaborating microelectronic and optoelectronic devices on polycrystalline silicon films. The I-V features of structures with p-n-junction, formed by using methods of р-type conductivity layer grow, thermal diffusion and ion-implantation of boron atoms into n-type polycrystalline silicon layer are compared. The I-V feature with S-form curve of the investigated structures conditioned by changing of the conductivities of base and grain boundaries under thermal processing are revealed.