ELECTROSTATIC FORCE MICROSCOPE IMAGING ANALYZED BY THE SURFACE-CHARGE METHOD

The electrostatic force acting between the probe of the force microscope and the sample surface is theoretically investigated by using the surface charge method. The actual shapes of the probe (an etched tungsten wire) and the sample (gratinglike electrodes) which are used in the experiments are considered to calculate the electrostatic forces quantitatively. It is shown that the macroscopic probe has to be taken into account for the force measurement. However, only the top part of the probe is responsive for the measurement of the force gradient. The imaging properties through the detection of the electrostatic force are also investigated experimentally by using the dynamic (ac) mode force microscope. The potentiometric and topographic effects on the imaging are discussed on the basis of theoretical calculations and the experimental results.