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 27.20: Poster

Dienstag, 24. März 2009, 18:30–21:00, P2

Near-field Scanning Thermal Microscope: From temperature to heat flow — •Ludwig Worbes, Uli F. Wischnath, and Achim Kittel — Universität Oldenburg EHF EPKOS

The Near-field Scanning Thermal Microscope (NSThM) developed in our group combines the function of a normal STM with the ability to use the scanning probe as a thermocouple temperature sensor [1].

By operating in UHV in our experiment the heat transfer mechanism is restricted to radiative transfer in contrast to other SThM devices. The radiative transfer is dominated by evanescent modes of the thermal electromagnetic field for small distances. The heat transfer mediated by these modes between sample and sensor has been calculated using different theoretical approaches.

In order to compare the theoretical predictions with the experiment, we need to know the relation between the measured thermovoltage and the heat flow. This is up to now done by calculating the thermal conductivity of the tip based on the geometry and material properties. Here we present a calibration procedure based on measuring the heat flow trough a bridge structure, whose thermal conductivity is easier to quantify. We use the so called 3ω method, using the bridge as a heater and as a resistive temperature sensor at the same time.

[1] U. F. Wischnath, J. Welker, M. Munzel, and A. Kittel, Rev. Sci. Instrum. 79, 073708 (2008).