Regensburg 2007 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 15: Methods: Scanning Probe Techniques II

O 15.7: Vortrag

Montag, 26. März 2007, 15:45–16:00, H41

Kelvin Probe Force Microscopy on Electrically Inhomogeneous Fe/W(001) Films — •Ung Hwan Pi, Rene Schmidt, Alexander Schwarz, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg

Noncontact scanning force microscopy can give information about the real topography of the sample. However, this is valid only when the dominant tip-sample interaction is due to the van der Waals force. If the sample is electrically inhomogeneous, e.g., the sample has an inhomogeneous electric charge distribution, it causes additional electrostatic forces between tip and sample, which prevent real topography measurement. To nullify the electrostatic effect, the tip bias can be regulated with a special feedback scheme called Kelvin probe force microscopy. Here we applied Kelvin probe force microscopy to the pseudomorphic Fe thin film grown on W(001). In this highly strained film, the electric properties depend on the number of layers, yielding different contact potentials in each layer. The samples were prepared and measured in-situ under ultra high vacuum condition without exposing them to the atmospheric environment. When the tip bias was not regulated, the apparent step height of the film changed depending on the tip-sample bias, and a reliable measurement of topography was impossible. With Kelvin probe force microscopy, the contact potentials different in each layer could be compensated, and the real topography image could be obtained.