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Fabrication of Nanostructures Using Atomic Force Microscopy
Doupal, Antonín ; Škoda, David (referee) ; Bartošík, Miroslav (advisor)
This bachelor thesis deals with fabrication of nanostructures using atomic force microscopy. The theoretical part gives a brief introduction into atomic force microscopy and local anodic oxidation and it is based on literature retrieval. The experimental part is concentrated on investigation of influence of operational parameters (tip-sample voltage, speed of the tip) on dimensions of LAO nanostructures on Si(111). Further the selective growth of cobalt and gallium on such oxide nanostructures is observed and analysed.
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Studium interakce adsorbátu s pasivovanými povrchy Si pomocí STM
Matvija, Peter ; Kocán, Pavel (advisor) ; Švec, Martin (referee)
The scanning tunneling microscopy is used to study the morphology of Tl adlayer in various stages of Tl desorption from the Si(111) surface and to study behaviour of various adsorbates on the Si(111)/Tl-(1 × 1). The utilization of thallium layer for passivation of the Si(111) was examined closely for various adsorbates. Manganese, aluminium, indium and tin layers which were directly deposited onto the Si(111)-(7 × 7) were compared with the layers prepared by deposition of adsorbate onto the passivating layer after the subsequent thermal desorption of Tl (after annealing at ≈ 400◦ C). Examined adsorbates exhibited signs of extremely high diffusivity and weak bond with the surface Si(111)/Tl- (1 × 1). The passivating layer was stable against the adsorbates.The application of thallium in the role of surfactant caused lowering of temperature and coverage needed for the preparation of reconstructions which were observed on the surfaces prepared by the direct deposition of adsorbate. 1
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Interaction of metal atoms with metastable reconstructions of the Si(111) surface studied by STM
Matvija, Peter ; Kocán, Pavel (advisor) ; Ošťádal, Ivan (referee)
Process of reconstruction of Si(111) surface after vapor deposition of thallium and subsequent desorption is studied by STM. Dependency of surface coverage on temperature is determined and this dependency is afterwards used for determination of ideal conditions for creation of surface with the biggest possible part with metastable reconstructions (mostly (5x5) and (9x9)). This surface is then covered by vapor deposition by different amounts of Al and possibility of creation of magic clusters and other interesting structures is investigated. Structural models for magic clusters on (5x5) are proposed. The work includes description of experimental devices used in measurements as well as description of procedures and physical principles connected with functioning of STM.
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Interaction of adsorbates with passivated Si surfaces studied by STM
Matvija, Peter ; Kocán, Pavel (advisor)
The scanning tunneling microscopy is used to study the morphology of Tl adlayer in various stages of Tl desorption from the Si(111) surface and to study behaviour of various adsorbates on the Si(111)/Tl-(1 × 1). The utilization of thallium layer for passivation of the Si(111) was examined closely for various adsorbates. Manganese, aluminium, indium and tin layers which were directly deposited onto the Si(111)-(7 × 7) were compared with the layers prepared by deposition of adsorbate onto the passivating layer after the subsequent thermal desorption of Tl (after annealing at ≈ 400◦ C). Examined adsorbates exhibited signs of extremely high diffusivity and weak bond with the surface Si(111)/Tl- (1 × 1). The passivating layer was stable against the adsorbates.The application of thallium in the role of surfactant caused lowering of temperature and coverage needed for the preparation of reconstructions which were observed on the surfaces prepared by the direct deposition of adsorbate. 1
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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...
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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...
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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...
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Modification of silicon surfaces for selective adsorption
Doležal, Jiří ; Ošťádal, Ivan (advisor) ; Matvija, Peter (referee)
This thesis is focused on adsorption of phthalocyanines on tin and indium passivated silicon Si(111) surfaces with the √3 × √3 reconstruction at room temperature. Scanning tunneling microscopy was used for obtaining atomically resolved surface images. Molecules on these surfaces predominantly adsorb on Si-substitutional defects. Local density of states (LDOS) of strongly adsorbed molecules was obtained by scanning tunneling spectroscopy. The origin of fuzzy imaging of molecules sitting on Si-substitutional double defects was probed. Voltage dependence of mean lifetime of two observed states, between which the "fuzzy" molecule is switching, was measured by analysis of tunneling current fluctuations. We discussed the influence of external parameters on the switching between the two states. We attribute the fuzzy behaviour of the molecule and resulting tunneling current fluctuations to the motion of the molecule in a double-well potential and propose two most likely kinds of the motion which most closely agree with the obtained data.
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Computer simulations of characteristics of metal desorption from the Si(111) surface
Sikora, Adam ; Kocán, Pavel (advisor) ; Mysliveček, Josef (referee)
Title: Computer simulations of characteristics of metal desorption from the Si(111) surface Author: Adam Sikora Department: Department of Surface and Plasma Science Supervisor: RNDr. Pavel Kocán, Ph.D. Abstract: In case of desorption of some metals (Pb, In, Ga) from surfaces Si(111) and Ga(111) was by use of integral techniques surprisingly observed zero-order of desorption. Theoretical explanation of zero-order is still missing, since it appears that the conditions that normally lead to desorption of the zeroth order - high diffusivity, the existence of 2D gaseous phase etc. - can not be met. The aim of this work is to develop kinetic Monte Carlo computer code for simulations of atomic processes on the surface of Si(111). The developed code will then be used for investigation of desorption spectra for various parameters and also for finding the parameters which allow the zero-order desorption. Keywords: Kinetic Monte Carlo, temperature programmed desorption, zero-order desorption, Si(111) 1
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Studium interakce adsorbátu s pasivovanými povrchy Si pomocí STM
Matvija, Peter ; Kocán, Pavel (advisor) ; Švec, Martin (referee)
The scanning tunneling microscopy is used to study the morphology of Tl adlayer in various stages of Tl desorption from the Si(111) surface and to study behaviour of various adsorbates on the Si(111)/Tl-(1 × 1). The utilization of thallium layer for passivation of the Si(111) was examined closely for various adsorbates. Manganese, aluminium, indium and tin layers which were directly deposited onto the Si(111)-(7 × 7) were compared with the layers prepared by deposition of adsorbate onto the passivating layer after the subsequent thermal desorption of Tl (after annealing at ≈ 400◦ C). Examined adsorbates exhibited signs of extremely high diffusivity and weak bond with the surface Si(111)/Tl- (1 × 1). The passivating layer was stable against the adsorbates.The application of thallium in the role of surfactant caused lowering of temperature and coverage needed for the preparation of reconstructions which were observed on the surfaces prepared by the direct deposition of adsorbate. 1
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