High potential sensitivity in heterodyne amplitude-modulation Kelvin probe force microscopy

A surface potential measurement method using amplitude-modulation and heterodyne techniques is proposed. The effect of the stray capacitance between a cantilever and a sample in Kelvin probe force microscopy and the electrostatic force spectroscopy measurements are almost completely removed, because the distance (z) dependence of the modulated electrostatic force increases from 1/z to 1/z(2). This method improves the sensitivity of short range forces and reduces the surface potential measurement crosstalk that is induced by topographic feedback. This method has the advantage of high potential sensitivity due to the high cantilever Q value under vacuum. Quantitative surface potential measurements are demonstrated. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4723697]