# Time-Resolved Open-Circuit Conductive Atomic Force Microscopy for Quantitative Analysis of Nanowire Piezoelectricity and Triboelectricity

## TL;DR

This paper introduces a novel open-circuit conductive AFM technique with time-resolved measurements for accurately quantifying nanowire piezoelectricity, overcoming limitations of traditional methods and revealing the coexistence of electromechanical effects.

## Contribution

It presents a new open-circuit cAFM methodology with time-resolved analysis for precise nanowire piezoelectric coefficient extraction, applicable to materials like GaAs.

## Key findings

- Standard short-circuit cAFM is inadequate for nanowire piezoelectric measurement.
- The proposed open-circuit, time-resolved method accurately measures piezoelectric coefficients.
- Results for GaAs nanowires align with existing theoretical values.

## Abstract

Piezoelectric nanowires are promising materials for sensing, actuation and energy harvesting, due to their enhanced properties at the nanoscale. However, quantitative characterization of piezoelectricity in nanomaterials is challenging due to practical limitations and the onset of additional electromechanical phenomena, such as the triboelectric and piezotronic effects. Here, we present an open-circuit conductive atomic force microscopy (cAFM) methodology for quantitative extraction of the axial piezoelectric coefficients of nanowires. We show, both theoretically and experimentally, that the standard short-circuit cAFM mode is inadequate for piezoelectric characterization of nanowires, and that such measurements are governed by competing mechanisms. We introduce an alternative open-circuit configuration, and employ time-resolved electromechanical measurements, to extract the piezoelectric coefficients. This method was applied to GaAs, an important semiconductor, with relatively low piezoelectric coefficients. The results obtained for GaAs,~0.4-1 pm/V, are in good agreement with existing knowledge and theory. Our method represents a significant advance in understanding the coexistence of different electromechanical effects, and in quantitative piezoelectric nanoscale characterization. The easy implementation will enable better understanding of electromechanics at the nanoscale.