Revisiting the switching characteristics and electroresistance effect in ferroelectric thin film towards an optimized hybrid switching strategy

Combining scanning force microscopy characterization and theoretical modeling, in this work, we performed an in-depth study on the electrical/mechanical switching and electroresistance effect in a BaTiO3 thin film. Correlations of the tip load (bias/force and loading time), the switched polarization magnitude, the surface potential, and the tunnel electroresistance are revealed for both electrical and mechanical switching. It is found that electrical switching (with a maximum bias of 4 V) leads to larger saturated switched polarization and sharper switched domain than mechanical switching (with a maximum force of 6600 nN). Meanwhile, mechanical switching exhibits generally smaller surface potential of the switched domain and a more significant tunnel electroresistance effect. However, the load time-dependence of performance is also more serious for mechanical switching. The different characteristics between electrical and mechanical switching are attributed to the charge injection and the switched domain size, which are believed to further affect the surface potential and the tunnel electroresistance of the thin film. At the end, an optimized hybrid switching strategy, which combines tip force and bias, is proposed and shown to be able to achieve complete polarization reversion, low charge injection, high switch speed, and strong tunnel electroresistance effect.