Correct height measurement in noncontact atomic force microscopy.
We demonstrate that topography measurements by noncontact atomic force microscopy are subject to residual electrostatic forces. On highly oriented pyrolitic graphite (HOPG) with a submonolayer coverage of C60, we monitor the step height from C60 to HOPG as a function of dc bias between tip and sample. Because of the different contact potential of C60 and HOPG ( approximately 50 mV), the step height is strongly dependent on the dc bias. The presented results and additional simulations demonstrate clearly that for correct height measurements it is mandatory to use a Kelvin probe force microscopy method with active compensation of electrostatic forces.
Sadewasser
Sascha
S
Hahn-Meitner Institut, Glienicker Strasse 100, 14109 Berlin, Germany.
Lux-Steiner
Martha Ch
MCh
D006108:Graphite / Q000737:chemistry; D018625:Microscopy, Atomic Force / Q000379:methods*; D055672:Static Electricity
D006108:Graphite