Kelvin probe force microscopy by direct dissipative electrostatic force modulation

TL;DR

This paper introduces a novel Kelvin probe force microscopy method utilizing dissipation signals from atomic force microscopy, enabling faster, simpler measurements with lower voltage requirements for electrical material characterization.

Contribution

The paper presents a new KPFM technique based on dissipation signals that simplifies implementation, enhances speed, and reduces voltage amplitude needed for electrostatic force detection.

Findings

Dissipation-based KPFM allows faster scanning without low frequency modulation.

Optimal phase for electrostatic force is 90°, maximizing dissipation signal.

The method requires smaller AC voltages due to resonance enhancement.

Abstract

We report a new experimental technique for Kelvin probe force microscopy (KPFM) using the dissipation signal of frequency modulation atomic force microscopy for bias voltage feedback. It features a simple implementation and faster scanning as it requires no low frequency modulation. The dissipation is caused by the oscillating electrostatic force that is coherent with the tip oscillation, which is induced by a sinusoidally oscillating voltage applied between the tip and sample. We analyzed the effect of the phase of the oscillating force on the frequency shift and dissipation and found that the relative phase of 90$^\circ$ that causes only the dissipation is the most appropriate for KPFM measurements. The present technique requires a significantly smaller ac voltage amplitude by virtue of enhanced force detection due to the resonance enhancement and the use of fundamental flexural mode oscillation for electrostatic force detection. This feature will be of great importance in the electrical characterizations of technically relevant materials whose electrical properties are influenced by the externally applied electric field as is the case in semiconductor electronic devices.