Increasing the SNR of Electrical AFM Methods by Active Mechanical Q-control

Abstract

This paper investigates the benefit of active mechanical Q-control for electrical surface potential measurements in atomic force microscopy. The effective quality-factor of the electrically stimulated cantilever oscillation is additionally increased mechanically at the same frequency with an active analog Q-controller, while in lift-mode. It is shown experimentally that the cantilever oscillation amplitude and therefore the measurement sensitivity is improved by a factor of 15. By spectral noise analysis around the resonance frequency of the cantilever, an increase of the signal-to-noise ratio from 2.5dB to 23dB is achieved.