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D. Kohl, P. Mesquida, G. Schitter:
"Quantitative AC - Kelvin Probe Force Microscopy";
Microelectronic Engineering, 176 (2017), S. 28 - 32.

This paper presents a novel feedback based Scanning Probe Microscopy method which enables quantitative
surface potential measurements without the need of the DC bias of Kelvin Probe Force Microscopy. In addition
to the sinusoidal excitation signal at frequency y, a sinusoidal signal with the frequency 2y is applied
to the conductive cantilever. By modulating the amplitude of the signal at 2y, the resulting electric force
component at the frequency y can be nullified by a feedback controller. When the force and, hence, the
cantilever oscillation is zero, the required amplitude represents the quantitative surface potential. Recording
this amplitude while scanning over the sample allows to acquire a two dimensional map of the surface
potential. The AC-KPFM method, shown analytically and with experimental results, keeps the compensation
based principle of classical KPFM, resulting in quantitative measurements but without the need of a DC bias.

SPM, AFM, KPFM, DC free, surface potential