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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Engineering of carbon electronic devices using focused electron beam induced deposition (FEBID) of graphitic nanojoints

Kim, Songkil 12 January 2015 (has links)
This thesis concerns development and characterization of the FEBID technique to improve interfacial properties at MWCNT/graphene-metal junctions by forming graphitic nanojoints using hydrocarbon precursors. A fabrication protocol for ultralow-resistant, Ohmic contacts at MWCNT-metal junctions with FEBID graphitic nanojoints was developed, based on an in-depth topological/ compositional/electrical material characterization, yielding high performance “end” contacts to multiple conducting channels of MWCNT interconnect. Using the FEBID technique as a contact fabrication tool, three fabrication strategies of electrical contacts between the mechanically exfoliated multilayer graphene and a metal interconnect using graphitic nanojoints were proposed and demonstrated experimentally, suggesting one of them, the post-deposited FEBID graphitic interlayer formation, as the most efficient strategy. A patterned CVD grown monolayer graphene, which is a promising material for large area graphene device fabrication, was contacted to metal electrodes through the FEBID graphitic interlayer, whose formation and chemical coupling to graphene and metal were theoretically and experimentally explored. The effects of FEBID process on the graphitic interlayer formation and graphene electronic devices were demonstrated through electrical measurements, including the transmission line method (TLM) measurements for separate evaluation of sheet and contact resistances. Modifications of the graphene channel as well as interfacial properties of the graphene-metal junctions were achieved, highlighting a unique promise of the FEBID technique as a tool for enhancing chemical, thermo-mechanical, and electrical properties of graphene-metal interfaces along with controllable tuning of doping states of the graphene channel.
2

Depozice pomocí fokusovaného elektronového svazku / Focused eletron beam induced deposition

Juřík, Karel January 2020 (has links)
Within this work, a set of depositions induced by focused electron beam was prepared. The depositions were prepared in the presence of water vapours from trimethyl(methylcyclopentadienyl)platinum(IV) precursor. The dependence of prepared materials purity on beam accelerating voltage and water vapour pressure was measured. The best platinum content was achieved at (27,2 ± 0,4) at. %, with beam accelerating voltage 5 kV, beam current 1600 pA and water vapour pressure 100 Pa. Due to subsequent long-term exposure to light, air humidity and air oxygen, the platinum content was increased to (39,2 ± 2,1) at. %.
3

Korelovaná sondová a elektronová mikroskopie pro studium moderních magnetických nanomateriálů / Correlated probe and electron microscopy for the study of modern magnetic nanomaterials

Novotný, Ondřej January 2021 (has links)
High pressure on the development of new magnetic materials and their miniaturization also emphasizes the development of new analytical techniques. This diploma thesis deals with the development and demonstration of correlated magnetic force and electron microscopy, which is a promising tool for the characterization of magnetic nanomaterials. The first part of this thesis describes the fundamental physics of micromagnetism with a focus on cylindrical nanofibers. The following pages describe optic, probe, electron, and synchrotron methods for mapping the magnetic properties of materials. The next part describes magnetic domain wall motion in cylindrical nanowires performed as a part of a more extensive material study. The last part of the thesis describes the development of correlated magnetic force and electron microscopy on LiteScope device. A production of magnetic probes was designed and successfully tested. Probes were fabricated by focused electron beam-induced deposition from the Co2(CO)8 precursor. Further, the developed correlated microscopy is demonstrated on a multilayer PtCo sample, magnetic cylindrical nanofibers, NiFe vortex structures, and FeRh metamagnetic nano-islands.
4

Aplikace fokusovaného iontového a elektronového svazku v nanotechnologiích / Application onf the Focused Ion on Electron Beam in Nanotechnologies

Šamořil, Tomáš January 2016 (has links)
Nowadays, the systems that allow simultaneous employment of both focused electron and ion beams are very important tools in the field of micro- and nanotechnology. In addition to imaging and analysis, they can be used for lithography, which is applied for preparation of structures with required shapes and dimensions at the micrometer and nanometer scale. The first part of the thesis deals with one lithographic method – focused electron or ion beam induced deposition, for which a suitable adjustment of exposition parameters is searched and quality of deposited metal structures in terms of shape and elemental composition studied. Subsequently, attention is paid also to other types of lithographic methods (electron or ion beam lithography), which are applied in preparation of etching masks for the subsequent selective wet etching of silicon single crystals. In addition to optimization of mentioned techniques, the application of etched silicon surfaces for, e.g., selective growth of metal structures has been studied. The last part of the thesis is focused on functional properties of selected 2D or 3D structures.

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