Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)

O 29.49: Poster

Mittwoch, 29. März 2006, 14:30–17:30, P2

Contact potential reading with a high-resolution tuning-fork AFM using a cantilever tip — •Sebastian Teich, Stefan Grafström, Christian Loppacher, Ulrich Zerweck, and Lukas M. Eng — Institute of Applied Photophysics, University of Technology Dresden, 01062 Dresden

We report on a home-built tuning-fork non-contact atomic force microscope (AFM) operated with phase-sensitive electronics in the FM demodulation mode. One prong of the tuning fork is glued to a support mounted on the scanner piezo [1]. An ac voltage applied to the tuning fork electrodes induces a vibration of the free prong with an amplitude of 1-5 nm normal to the sample surface. We measure the oscillation amplitude by detecting the induced current using a lock-in amplifier. An electronic circuit compensates for the background signal originating from direct capacitive pick-up of the drive voltage. The probe-sample distance is controlled by a feeback loop such that the resonance frequency coincides with the given driving frequency. A second feedback keeps the mechanical oscillation amplitude constant, thereby providing information on the dissipation caused by the tip-sample interaction. As a probe, a commercial cantilever tip is glued to the tuning fork [2]. Various topographic structures with characteristic length scales down to 10 nm could be resolved. Furthermore, aiming for Kelvin probe force microscopy, we made the tip conductive and contacted it to one of the electrodes of the tuning fork by evaporating a metal layer onto the tip.

[1] F.J. Giessibl et al., Nanotechnology 15 (2004) S79

[2] S. Rozhok and V. Chandrasekhar, Sol. Stat. Comm. 121 (2002) 683