Piezoresponse force and electrochemical strain microscopy in dual AC resonance tracking mode: Analysis of tracking errors

Abstract

Contact-resonance atomic force microscopy allows the quantitative mapping of local viscoelastic and electromechanical properties. Excitation and amplification are generally described by the damped harmonic oscillator (DHO) model. The dual AC resonance tracking technique measures the amplitude and phase at two probing frequencies close to the resonance frequency and calculates the parameters of the DHO model from the amplitudes and phases. However, real systems show contact-resonance curves with slight deviations from the DHO model. In this work, we analyze how these deviations influence the obtained DHO parameters. We show that for a piezoelectric sample and for a mixed ion-electron conducting sample, the drive amplitude increases with increasing tracking error, while the opposite is observed for the amplification factor. Thus, in electrochemical strain microscopy experiments, the influence of the tracking error on the DHO parameters can be analyzed by calculating a tracking error image and studying correlations with the DHO parameter images.