|
|
SPM Methods Based On The Quartz Resonator Probes
Wertheimer, Pavel ; Sobotík, Pavel (referee) ; Číp, Ondřej (referee) ; Šikola, Tomáš (advisor)
The thesis is focused on development of scanning probe microscope systems, especially development and implementation of quartz resonator probes. The quartz resonator probes, compared to the standard silicon cantilevers, have several advantages. It is in particular their mechanical properties and possibility of direct electrical readout of the deflection signal. Due to the fact, the probes are easy to implement even into more complex SPM systems. The thesis deals with development of universal and open SPM control system electronics. The electronics consist of the commercial SPM control and oscillation units, the development of the other electronic parts (such as the high voltage amplifier and the preamplifier units) is described in the thesis. Further, the thesis reports on development of the qPlus UHV LT SPM microscope system that was carried out at Universität Hamburg. Part of it was development of the qPlus preamplifier able to operate at liquid helium temperature. The third topic of the thesis is the implementation of qPlus technology into the UHV VT SPM microscope suitable to operate in situ with a scanning electron microscope. The qPlus sensors and the universal UHV preamplifier were designed and manufactured. Test measurements were conducted on all of the developed systems.
|
|
|
Interaction of simple organic molecules with cerium oxide surfaces
Ormoš, Martin ; Matvija, Peter (advisor) ; Sobotík, Pavel (referee)
In this work we prepare well defined thin epitaxy layers of cerium oxide (CeO2) and cerium oxide with nanoparticles of platinum (CeO2/Pt) on the Cu(111) substrate. The surface was characterized before exposition by ethanol molecules, after exposition, after annealing at 725 K in UHV and after annealing in O2 atmosphere at pressure p = 5×10−7 mbar at 725 K by LEED (low-electron energy diffraction), XPS (x-ray photoelectron di- ffraction) and STM (scanning tunnelling microscopy). Layer of CeO2/Pt was also exposed to 2 mbar of methane and 2, 5 mbar of methane and oxygen mixture in a ratio 1:1. This layer was observed by NAP-STM in higher pressures. In this work we have discovered that a disordered layer is formed on the CeO2 surface after exposure to the mixture of air and ethanol. Interaction of adsorbed molecules and ceria is increased during annealing in UHV, when carbon desorbs from the surface and cerium is reduced. After annealing in oxygen cerium is reoxidized. However, even after reoxidation, the surface contains a large number of defects of various types. Significant increase in brightness was observed in the proximity of domain interfaces of cerium oxide layers during scanning at higher pressures of oxygen. This effect will be studied more closely in our future experiments. 1
|
|
| |
|
| |
|
|
STM/STS study of bimetallic nanostructures on silicon surfaces
Zimmermann, Petr ; Sobotík, Pavel (advisor) ; Mysliveček, Josef (referee)
In this study we examine linear nanostructures consisting of metals of III. (Al, In) and IV. (Sn) group on the Si(001)2×1 surface by means of scanning tunnelling microscopy & spectroscopy. Atoms on the surface align into atomic chains growing perpendicularly to the dimer rows of the surface reconstruction. The chain structure consists of dimers that adsorb in the troughs between the dimer rows of the surface reconstruction. We observe that the chains consist of sequences of homodimers of either elements combining with heterodimers. The InSn chain structure is analysed with regard to theoretical ab-initio calculations of the chain dimer structure. The model is then applied to the Al-Sn system. We observe that the Al-Sn chains tend to consist of aligned heterodimers. The appearance of heterodimers in STM depends on the chemical composition of the neighbouring dimers. We can also observe the tendency of chains to agglomerate and via Sn atoms create quasi periodic 2D structures. The electronic structure of an Al, Sn and mixed AlSn dimer is studied by means of tunnelling spectroscopy. Despite its small, nonzero density of states on the Fermi energy, the character of the mixed dimer appears to be rather non-conductive.
|
|
| |
|
|
Interaction of organic molecules with metal passivated semiconductor surfaces studied via STM
Zimmermann, Petr ; Sobotík, Pavel (advisor)
Title Interaction of Organic Molecules with Metal Passivated Silicon Surfaces Studied via STM Author Petr Zimmermann Department Department of Plasma and Surface Science Supervisor Doc. RNDr. Pavel Sobotík, CSc. Department of Plasma and Surface Science Abstract Organic molecules offer a wide range of optical, electronic or chemical properties. Coupling them to silicon could pave way to novel applications and devices, however, a controlled molecular functionalization of silicon remains challenging due to the presence of highly reactive dangling bonds on its surfaces. We attempt to decrease the reactivity of low index silicon surfaces with an ultra-thin layer of a metal adsorbates and study their interaction with organic molecules via scanning tunnelling microscopy. In the first part we investigate the interaction of ethylene, a small unsaturated molecule, with tin and indium 1D chains grown on Si(001) - 2 × 1. The chains consist of dimers structurally analogous to the dimers of the underlying Si(001) - 2 × 1 surface. Aided by photoelectron spectroscopy we find that the Sn chains are less reactive than the Si(001) surface and that the absence of a π dimer bond renders indium chains inert. In the second part we study the interaction of copper phthalocyanine, a small macrocyclic heteroaromatic compound, with the...
|
|
|
Interaction of organic molecules with metal passivated semiconductor surfaces studied via STM
Zimmermann, Petr ; Sobotík, Pavel (advisor)
Title Interaction of Organic Molecules with Metal Passivated Silicon Surfaces Studied via STM Author Petr Zimmermann Department Department of Plasma and Surface Science Supervisor Doc. RNDr. Pavel Sobotík, CSc. Department of Plasma and Surface Science Abstract Organic molecules offer a wide range of optical, electronic or chemical properties. Coupling them to silicon could pave way to novel applications and devices, however, a controlled molecular functionalization of silicon remains challenging due to the presence of highly reactive dangling bonds on its surfaces. We attempt to decrease the reactivity of low index silicon surfaces with an ultra-thin layer of a metal adsorbates and study their interaction with organic molecules via scanning tunnelling microscopy. In the first part we investigate the interaction of ethylene, a small unsaturated molecule, with tin and indium 1D chains grown on Si(001) - 2 × 1. The chains consist of dimers structurally analogous to the dimers of the underlying Si(001) - 2 × 1 surface. Aided by photoelectron spectroscopy we find that the Sn chains are less reactive than the Si(001) surface and that the absence of a π dimer bond renders indium chains inert. In the second part we study the interaction of copper phthalocyanine, a small macrocyclic heteroaromatic compound, with the...
|
|
|
Interaction of organic molecules with metal passivated semiconductor surfaces studied via STM
Zimmermann, Petr ; Sobotík, Pavel (advisor) ; Plšek, Jan (referee) ; Šikola, Tomáš (referee)
Title Interaction of Organic Molecules with Metal Passivated Silicon Surfaces Studied via STM Author Petr Zimmermann Department Department of Plasma and Surface Science Supervisor Doc. RNDr. Pavel Sobotík, CSc. Department of Plasma and Surface Science Abstract Organic molecules offer a wide range of optical, electronic or chemical properties. Coupling them to silicon could pave way to novel applications and devices, however, a controlled molecular functionalization of silicon remains challenging due to the presence of highly reactive dangling bonds on its surfaces. We attempt to decrease the reactivity of low index silicon surfaces with an ultra-thin layer of a metal adsorbates and study their interaction with organic molecules via scanning tunnelling microscopy. In the first part we investigate the interaction of ethylene, a small unsaturated molecule, with tin and indium 1D chains grown on Si(001) - 2 × 1. The chains consist of dimers structurally analogous to the dimers of the underlying Si(001) - 2 × 1 surface. Aided by photoelectron spectroscopy we find that the Sn chains are less reactive than the Si(001) surface and that the absence of a π dimer bond renders indium chains inert. In the second part we study the interaction of copper phthalocyanine, a small macrocyclic heteroaromatic compound, with the...
|
|
|
Analýza fluktuací tunelového proudu v STM
Sopoušek, Jan ; Ošťádal, Ivan (advisor) ; Sobotík, Pavel (referee)
The thesis deals with analysis of fluctuations of the tunnelling current in scanning tunnelling microscopy (STM). The dynamics of Sn atoms on the surface Si (111) 7x7 is studied by means of time records of the tunnelling current. The records provided characteristic times of Sn adatom staying in various areas of half unit cells of the surface reconstructions are analysed. The model types of the tunnelling current interference, which influence the measurement accuracy, are also studied. Powered by TCPDF (www.tcpdf.org)
|
guest ::
