iDART: Interferometric Dual-AC Resonance Tracking nano-electromechanical mapping

TL;DR

iDART is a novel interferometric technique that significantly enhances the sensitivity and reliability of nanoscale electromechanical imaging, enabling detailed studies of weak piezoelectric signals in various advanced materials.

Contribution

The paper introduces iDART, combining interferometry with resonance tracking to achieve over 10x sensitivity improvements in PFM imaging compared to existing methods.

Findings

Achieved >10x signal-to-noise ratio improvement in PFM imaging.

Enabled reliable hysteresis measurements at small biases.

Demonstrated effectiveness on PZT and Y-HfO thin films.

Abstract

Piezoresponse force microscopy (PFM) has established itself as a very successful and reliable imaging and spectroscopic tool for measuring a wide variety of nanoscale electromechanical functionalities. Quantitative imaging of nanoscale electromechanical phenomena requires high sensitivity while avoiding artifacts induced by large drive biases. Conventional PFM often relies on high voltages to overcome optical detection noise, leading to various non-ideal effects including electrostatic crosstalk, Joule heating, and tip-induced switching. To mitigate this situation, we introduce interferometrically detected, resonance-enhanced dual AC resonance tracking (iDART), which combines femtometer-scale displacement sensitivity of quadrature phase differential interferometry with contact resonance amplification. Through this combination, iDART achieves 10x or greater signal-to-noise improvement over current state of the art PFM approaches including both single frequency interferometric PFM or conventional, resonance enhanced PFM using optical beam detection. In this work, we demonstrate a >10x improvement of imaging sensitivity on PZT and Y-HfO. Switching spectroscopy shows similar improvements, where further demonstrates reliable hysteresis loops at small biases, mitigating nonlinearities and device failures that can occur at higher excitation amplitudes. These results position iDART as a powerful approach for probing conventional ferroelectrics with extremely high signal to noise down to weak piezoelectric systems, extending functional imaging capabilities to thin films, 2D ferroelectrics, beyond-CMOS technologies and bio-materials.