EFFECT OF ELECTROSTATIC FORCE AND TAPPING MODE-OPERATION OF ATOMIC-FORCE MICROSCOPE

We investigated tip-sample interaction under an electrostatic field. W e have also demonstrated the tapping mode microscopy using an electros tatic force modulation. By applying de and ac bias voltages between th e probe and sample, we measured the de and ac electrostatic force. Our result indicates that the ac force curve as a function of tip to samp le distance produces more quantitative information on the tip-sample i nteraction than the de force curve. The ac force vs. distance curve ca n be used for the tapping mode operation of the microscope using the e lectrostatic force. The tapping mode technique can be applied to obtai n the image of soft samples with a high spatial resolution. In additio n, by applying the tapping mode technique, we measured the surface pot ential and topography of a test device simultaneously.