Surface Contamination: A Natural Way toward High-Resolution Electric Force Microscopy in Contact-Resonant Mode

Abstract

Electric force microscopy (EFM)-based methods have the capacity to probe surface potential, dielectric properties, and surface charges. It can be robustly used for analyzing charge-transfer mechanisms in nanostructures by measuring the electrostatic forces between a sample surface and a tip. The highest achievable resolution for conventional EFM under ambient conditions is defined mainly by the tip–sample separation d, which is limited by the “jump-to-contact” effect. In this paper, the contact-resonance EFM methodology operating at close to zero d is demonstrated, which is applicable to semiconductors, metals, and dielectrics. Being implemented at the contact resonance frequency of the atomic force microscopy probe in contact with the surface, it allows an improvement in the sensitivity and boosting of the signal-to-noise ratio and it enables the condition required for high-resolution imaging. Furthermore, the critical role of nonconducting organic compounds to achieve a smaller d, and subsequently enhancing the electrostatic signal, is addressed.