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Continuous Control of Charge Transport in Bi-Deficient BiFeO3 Films Through Local Ferroelectric Switching



It is demonstrated that electric transport in Bi-deficient Bi1-δFeO3 ferroelectric thin films, which act as a p-type semiconductor, can be continuously and reversibly controlled by manipulating ferroelectric domains. Ferroelectric domain configuration is modified by applying a weak voltage stress to Pt/Bi1-δFeO3/SrRuO3 thin-film capacitors. This results in diode behavior in macroscopic charge-transport properties as well as shrinkage of polarization-voltage hysteresis loops. The forward current density depends on the voltage stress time controlling the domain configuration in the Bi1-δFeO3 film. Piezoresponse force microscopy shows that the density of head-to-head/tail-to-tail unpenetrating local domains created by the voltage stress is directly related to the continuous modification of the charge transport and the diode effect. The control of charge transport is discussed in conjunction with polarization-dependent interfacial barriers and charge trapping at the non-neutral domain walls of unpenetrating tail-to-tail domains. Because domain walls in Bi1-δFeO3 act as local conducting paths for charge transport, the domain-wall-mediated charge transport can be extended to ferroelectric resistive nonvolatile memories and nanochannel field-effect transistors with high performances conceptually.