Simulation of section curve by phase constant dynamic mode atomic force microscopy in non-contact situation

Abstract

We investigate the behavior of an oscillating tip operating in tapping mode, e.g. with fixed drive frequency and drive excitation while scanning horizontally an ideal flat surface holding a small corrugation. The numerical simulations are performed to compare the relative vertical and lateral sensitivity of the oscillator when the feedback loop controlling the tip–sample distance keeps constant the oscillator phase instead of the amplitude. In these simulations, a sphere lies on a flat surface and a Van der Waals force is assumed between the tip, the sphere and the substrate. Once the tip has approached from the substrate far from the sphere, the tip is scanned towards the sphere. It is found that the phase constant mode makes smaller indentation and better response height probably without larger damage by using wider setpoint value (SPV) than the cases of amplitude constant mode.