Measurement of surface potential and adhesion with Kelvin Probe Force Microscopy

We report a Kelvin Probe Force Microscope (KPFM), which can scan surface potential and adhesion. Single-pass pulsed force mode is proposed, to measure topography, contact potential difference (CPD) and adhesion force. For each measurement point, the tip perform an approach and retract from the sample. Therefore, the averaging effect which is an issue in amplitude modulation (AM)-KPFM, is greatly reduced. In addition, it has advantage of mechanical characterization of the sample at the same time as compare to frequency modulation (FM)-KPFM and AM-KPFM. Electrical and adhesion force of few-layer graphene on the n-doped silicon have been measured. The results show that the performance of proposed KPFM is better than AM-KPFM in measuring CPD while frequency modulation (FM)-KPFM has higher CPD resolution due to being sensitive to force gradient. The electrostatically caused adhesion errors in measuring adhesion force are compensated by the kelvin testing loop.