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Bachelor's Thesis
Author of thesis: Ing. Martina Ondříšková
Acad. year: 2021/2022
Supervisor: doc. Ing. Alexandr Knápek, Ph.D.
Reviewer: doc. Mgr. Dinara Sobola, Ph.D.
Cathodes containing arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire to maximize current and current density leads to the design of denser arrays. However, denser arrays lead to undesirable field shielding effects caused by the presence of surrounding emitters in the array. To reduce the shielding effect and thus maximize the field enhancement, an array of emitters was designed with an arrangement inspired by the natural phenomenon of phyllotaxis. The structure thus designed was created using electron beam lithography and reactive ion etching to form micropillars. A black silicon etching technique was used to create ultra-sharp tips with a radius in the order of tens of nanometers on the top of each micropillar. Analysis of the sample topography was performed by Scanning electron microscopy. Ultraviolet photoelectron spectroscopy was used to determine the work function. To find out the emission properties of the fabricated structures, a Field emission microscope was constructed and its electron gun was modified to experimentally use the fabricated structure as the cathode. A Murphy-Good plot was used to analyze the field emission data, to which the orthodoxy test was applied to check the validity of the experimental I-V data. Current stability measurement was performed to observe current fluctuations.
Field emitter array (FEA), electron beam lithography (EBL), reactive ion etching (RIE), black silicon, scanning electron microscopy (SEM), ultraviolet photoelectron spectroscopy (UPS), field emission microscopy (FEM).
Date of defence
17.06.2022
Result of the defence
Defended (thesis was successfully defended)
Grading
A
Process of defence
Po otázkách oponenta bylo diskutováno Povrchová citlivost metody XPS. Studentka na otázku odpověděla.
Language of thesis
English
Faculty
Fakulta strojního inženýrství
Department
Institute of Physical Engineering
Study programme
Physical Engineering and Nanotechnology (B-FIN-P)
Composition of Committee
prof. RNDr. Tomáš Šikola, CSc. (předseda) prof. RNDr. Jiří Spousta, Ph.D. (místopředseda) doc. Ing. Stanislav Průša, Ph.D. (člen) doc. Mgr. Vlastimil Křápek, Ph.D. (člen) doc. Ing. Miroslav Bartošík, Ph.D. (člen) prof. RNDr. Petr Dub, CSc. (člen) prof. RNDr. Bohumila Lencová, CSc. (člen) prof. RNDr. Miroslav Liška, DrSc. (člen) prof. Ing. Miroslav Kolíbal, Ph.D. (člen) prof. RNDr. Radim Chmelík, Ph.D. (člen) doc. Ing. Radek Kalousek, Ph.D. (člen) RNDr. Antonín Fejfar, CSc. (člen)
Supervisor’s reportdoc. Ing. Alexandr Knápek, Ph.D.
Grade proposed by supervisor: A
Reviewer’s reportdoc. Mgr. Dinara Sobola, Ph.D.
Grade proposed by reviewer: A
Responsibility: Mgr. et Mgr. Hana Odstrčilová