Peter Milde

Visualisation of Local Charge Densities with Kelvin Probe Force Microscopy

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Kurzfassung in Englisch

For the past decades, Kelvin probe force microscopy (KPFM) developed from a sidebranch of atomic force microscopy to a widely used standard technique. It allows to measure electrostatic potentials on any type of sample material with an unprecedented spatial resolution. While the technical aspects of the method are well understood, the interpretation of measured data remains object of intense research. This thesis intends to prove an advanced view on how sample systems which are typical for ultrahigh resolution imaging, such as organic molecular submonolayers on metals, can be quantitavily analysed with the differential charge density model.
In the first part a brief introduction into the Kelvin probe experiment and atomic force microscopy is given. A short review of the theoretical background of the technique is presented.
Following, the differential charge density model is introduced, which is used to further explain the origin of contrast in Kelvin probe force microscopy. Physical effects, which cause the occurence of local differential charge densities, are reviewed for several sample systems that are of interest in high resolution atomic force microscopy.
Experimental evidence for these effects is presented in the second part. Atomic force microscopy was used for in situ studies of a variety of sample systems ranging from pristine metal surfaces over monolayer organic adsorbates on metals to ferroelectric substrates both, with and without organic thin film coverage.
As the result from these studies, it is shown that the differential charge density model accurately describes the experimentally observed potential contrasts. This implies an inherent disparity of the measurement results between the different Kelvin probe force microscopy techniques; a point which had been overseen so far in the discussion of experimental data. Especially for the case of laterally strong confined differential charge densities, the results show the opportunity as well as the necessity to explain experimental data with a combination of ab initio calculations of the differential charge density and an electrostatic model of the tip-sample interaction.

weitere Metadaten

Rastersondenmikroskopie, Rasterkraftmikroskopie, Kelvinsonde, Austrittsarbeit, Kontaktpotential
scanning probe microscopy, scanning force microscopy, kelvin probe force microscopy, work function, contact potential
SWD SchlagworteMikroskopie, Oberflächenphysik, Austrittsarbeit
DDC Klassifikation530, 531, 537, 539
RVK KlassifikationUP 7500, UH 6320
HochschuleTechnische Universität Dresden
FakultätFakultät Mathematik und Naturwissenschaften
ProfessurInstitut für Angewandte Physik / Photophysik
BetreuerProf. Lukas M. Eng
GutachterProf. Lukas M. Eng
Prof. Christian Loppacher
Tag d. Einreichung (bei der Fakultät)18.04.2011
Tag d. Verteidigung / Kolloquiums / Prüfung10.06.2011
Veröffentlichungsdatum (online)19.07.2011
persistente URNurn:nbn:de:bsz:14-qucosa-70867

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