The MFS and MFIS structures were prepared on the Si and PbO/Si substrate by the r.f. magnetron sputtering method. When the PbO buffer layer was inserted between the PZT thin film and Si substrate, the crystallization of the PZT thin films was considerably improved, and the processing temperature was lowered. Compared with the MFS structure, memory window values of the MFIS structure with the buffer layer were considerably improved. In particular, in the MFIS structure, the maximum value of the memory window is 2.0 V under the applied voltage of 9V for Pt/PZT (200 nm, 400ı)/PbO (80 nm)/Si structures with the PbO buffer layer deposited at the substrate temperature of 300ı.