Closed-Loop Simulation of Kelvin Probe Force Microscopy based on Reduced Finite Element Cantilever Modeling
Kelvin probe force microscopy (KPFM) is a method for simultaneous high-resolution imaging of topography and surface voltage. The image data is obtained from nested feedback loops by keeping the oscillation frequency and amplitude of the force-sensing microcantilever at different modulation frequencies constant. The present article deals with the development of a simulation model for KPFM operation. Emphasis is given to the accurate modeling of the microcantilever dynamics as a distributed system by finite element analysis, followed by a model reduction rendering the system suitable for closed-loop time-domain simulations and controller design. This approach enables the exploitation of higher eigenmodes and higher-harmonic components in the oscillation signal for imaging purposes. The successful implementation of the single-pass KPFM model is demonstrated by simulation results.