Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)
O 27.21: Poster
Dienstag, 24. März 2009, 18:30–21:00, P2
A Novel Scanning Tunneling Potentiometry Setup with Microvolt Resolution — •T. Druga1, M. Wenderoth1, M. A. Schneider2, and R. G. Ulbrich1 — 1IV. Phys. Inst., Georg-August-Univ. Göttingen — 2Lehrstuhl für Festkörperphysik Univ. Erlangen - Nürnberg
In Scanning Tunneling Potentiometry (STP) the tunneling tip is used as a weakly coupled voltage probe to determine the spatial variation of the electrochemical potential due to a lateral surface current or temperature difference between tip and sample. We have developed a potentiometric technique based on a standard STM setup allowing to measure the local potential with µV and Angstrom resolution. Unlike recent implementations [1,2] that use alternating voltages as transport fields or for controlling the tip sample distance similar to the scheme suggested by Muralt and Pohl [3] our STP method uses DC-voltages only. Hence it not only allows standard STS being conducted in parallel but also ensures correct assignment of the energy of tunneling electrons. Further advantages of our technique is that (i) the sample bias for the topography can be chosen independently from the potentiometry and (ii) the potential can be mapped simultaneously for reverse current directions. It has been implemented in both a room temperature and low temperature STM-setup. The performance is demonstrated by measuring local transport fields on Si(111)√3×√3-Ag and thermovoltage maps on Ag(111). This work was supported by the DFG as part of SFB 602 Tp A7. [1] Rev. Sci. Int. 79, 083704 (2008) [2] Rev. Sci. Int. 79, 073904 (2008) [3] Appl. Phys. Lett. 48, 514 (1986)