An approach to investigating the relationship between local ferroelectric and resistive properties in thin ferroelectric films using scanning tunneling microscopy

We propose a new approach based on Scanning Tunneling Microscopy (STM) / Spectroscopy (STS) under ultrahigh vacuum condition to study the correlation between the local resistive and ferroelectric (FE) properties of nanometer-thick FE films. The consideration of the oxide layer capacitance of the STM probe enables us to develop the polarization procedure of thin FE film providing the visualization of the local ferroelectric property distribution in scanning tunneling microscopy measurements.

It was found that a sequent voltage application provokes the modification of peculiarities of polarization charge screening on the FE film surface inside the STM tunnel barrier. The presence of this additional tunnel barrier between the surface of FE film and the STM probe affects the results of STS measurements. Thus, change in the amount of the adsorbed charges inside the STM tunnel barrier at sequent voltage application influences the I-V curves measurements used for evaluation of local resistive properties and could be mistaken for changes in the local resistive state of the FE film.

The developed approach allows us to eliminate an impact of polarization charge screening inside the STM tunnel barrier on the experimental results of polarization driven resistive property modification in thin FE films.