Probing the origins of electroresistance switching behavior in ferroelectric thin films

Ferroelectric thin films have been systematically investigated via scanning probe microscopy in recent years. Research indicates that the surface potential is the combined result of injected and polarization charges. The relationships between surface potentials and the two types of charges are usually investigated via scanning Kelvin probe microscopy (SKPM). Typically, SKPM investigations indicate that the surface charge distribution is dominated by injected charges trapped during poling using a conductive AFM tip rather than by polarization charges. The presence of injected charges leads to controversy concerning the origins of resistive switching behavior. In this study, relaxation of injected charges was observed during an optimized thermal treatment. This caused polarization charges to dominate over injected charges. Different electroresistance switching characterizations were observed via conductive atomic force microscopy (C-AFM) of injected and polarization charge-dominated films. Our research extends the methods of distinguishing whether electroresistance switching behavior is driven by charge trapping/detrapping or ferroelectric polarization. This provides an effective approach to classifying the origins of electroresistance switching in ferroelectric thin films by combining piezoelectric force microscopy, SKPM, and C-AFM.