Ferroelectric tunneling junctions (FTJs) based on tunneling electroresistance have great potential in non-volatile memory applications. The resistance states can be modulated by electric field and the switching property is nonvolatile in the FTJs. In this work, a 10-nm-thick PbTiO3 (PTO) was epitaxially grown on Nb doped SrTiO3 (NSTO) substrates to form Al/PTO/NSTO metal-ferroelectric-semiconductor structures (MFS). The non-volatile resistance switching in our MFS was demonstrated by electrical measurement. By fitting different conduction models, the electron transport was dominated by both barrier tunneling and defects, which was a mixture of interface effect and bulk effect. Such mechanism is quite different from the electroresistance based FTJs. The resistance switch is controlled by both polarization charge and structure defects. This result may expand the application of the MFS structures.