Fast multifrequency measurement of nonlinear conductance

TL;DR

This paper introduces a phase-coherent multifrequency lock-in technique using inverse Fourier transform to rapidly and accurately measure the nonlinear conductance of nanoscale junctions, overcoming traditional limitations.

Contribution

The method enables fast, high-resolution measurement of nonlinear IVCs in nanoscale systems by separating currents and canceling parasitic effects, significantly improving measurement speed.

Findings

Achieved several orders of magnitude increase in measurement speed.

Successfully measured IVCs at every pixel during atomic force microscopy scans.

Demonstrated effective separation of galvanic and displacement currents.

Abstract

We describe a phase-coherent multifrequency lock-in measurement technique that uses the inverse Fourier transform to reconstruct the nonlinear current-voltage characteristic (IVC) of a nanoscale junction. The method provides for a separation of the galvanic and displacement currents in the junction, and easy cancellation of the parasitic displacement current from the measurement leads. These two features allow us to overcome traditional limitations imposed by the low conductance of the junction and high capacitance of the leads, thus providing an increase in measurement speed of several orders of magnitude. We demonstrate the method in the context of conductive atomic force microscopy, acquiring IVCs at every pixel while scanning at standard imaging speed.