Measurement of the contact potential difference with an electrostatic force microscope

In this paper we present a method for the measurement of the contact potential difference (CPD) using an electrostatic force microscope. Nowadays, as with many other scanning force microscopes, the electrostatic force microscope enables the realization of multi-acquisition and thus the simultaneous observation of a topographic image and an image related to the CPD. More precisely, we propose a new principle for the measurement of the CPD based on the determination of the variations of the dynamic electrostatic force between a conductive tip and a sample. These variations are detected through the absolute amplitude of vibration of the tip measured by a heterodyne laser probe at high resolution. Evaluation of the CPD is obtained by recording two or four images of the sample with different parameters. A comparison between the literature data of the CPD and the experimental values for different samples shows relatively good agreement.