Impact on the electrostatic field of electrostatic force microscope due to tip-sample distance and non-flat sample surface

Finite element analysis of the electrostatic field of the electrostatic force microscope (EFM) has been conducted in this paper for various tip-sample distances and non-flat sample surfaces. It is found from the simulation that when the distance between probe tip and sample surface is within 0 nm to 3 nm, the electrostatic field between probe tip and sample surface is smaller compared to that of tip-sample distance above 3 nm. Moreover, non-flat sample surface can only make significant difference on the electrostatic field when the surface roughness is larger than 4 nm.