The ferroelectric potassium ion doped Sr075Ba025Nb2O6(SBN75) buffer layers were fabricated on Si(100) substrate by the sol-gel method, and the highly c-axis preferentially orientated SBN thin films on the KSBN buffer layers were obtained by the RF magnetron sputtering deposition. For the deposition of films, the corresponding preparation parameters have been optimized. It was found that the KSBN buffer layers can reduce the mis-match of crystalline lattices between the SBN film and the substrate effectively. When the ratio of O2/Ar pressure reached 1∶2, the working pressure was 10 Pa, and the sputtering power was 300W, the temperature of substrate was 300℃ and the post-annealing temperature was adjusted to 800℃, the c-axis highly preferentially orientated growth of SBN thin film can be realized. The microstructure of the thin films was investigated by XRD and AFM, and the p-n junction effect was found in our ITO/SBN/KSBN/Si structures, which is characteristic of semiconductor materials. The intensity of the junction effect was closely related to the presence of the buffer layer as well as the crystalline properties of SBN thin films.