|
|
Design of an effusion cell for the deposition of Sn and Zn ultrathin layers
Horák, Stanislav ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
This bachelor thesis deals with the design and the construction of effusion cells for the deposition of zinc and tin ultrathin layers. In the introductory part there is an explanation of principles of eusion cells' functions, like a molecular beam epitaxy (MBE) or a construction of the efussion ow. Furthermore, the work describes a general principles of a ccreation of the atom sources. Theoretical part ends with review about the growth of ultrathin layers and nanostructures of zinc, tin and their compounds. Experimental part provides a design of the effusion cells with radiation heating from silicon carbide and heating by electrons impact. The complete drawing documentation of the designed effusion cells is included in the attachment.
|
|
|
Preparation of GeSn nanostructures
Jedlička, Jindřich ; Voborný, Stanislav (referee) ; Kolíbal, Miroslav (advisor)
This bachelor thesis deals with the methods of preparation of GeSn nanowires. In the theoretical part of the thesis the band structure of solid states is described and the interesting properties of GeSn material are mentioned. The growth mechanism of nanowires and methods of preparation of GeSn nanowires are introduced. In the experimental part of the thesis the effusion cell for Sn deposition was assembled and the testing and calibration were performed.
|
|
|
Analysis of locally modified surfaces for selective growth of cobalt
Krajňák, Tomáš ; Bábor, Petr (referee) ; Čechal, Jan (advisor)
In this thesis the chemical composition of silicon substrates locally modified by focused gallium ion beam by X-ray photoelectron spectroscopy is determined. In order to determine the influence of focused ion beam, the sample comprising sputtered square areas with nominal depths in range of 1 to 10 nm was prepared. Next, the sample was heated to elevated temperatures (500 - 700 °C) to reveal changes in the sputtered areas induced by annealing. In this work by X-ray photoelectron spectrometer Kratos Supra and electron microscope Tescan LYRA3 with focused ion beam were used. From the measured spectra of the Si 2p and Ga 2p3/2 peaks measured as a function of nominal sputtering depth and annealing temperature the following main observations were obtained. First, there is the additional peak component in the Si 2p peak, which can be assigned to the amorphous silicon. The second important finding is that gallium can be removed from near surface volume by annealing at temperatures beyond 700 °C.
|
|
|
Design of manipulator for ultrahigh electron microscope
Caesar, Radek ; Mach, Jindřich (referee) ; Bábor, Petr (advisor)
The main purpose of this thesis is mechanical design of a manipulator for an ultra-high vacuum scanning electron microscope (UHV SEM), being currently developed by TESCAN ORSAY HOLDING a.s. in cooperation with the Institute of physical engineering FME BUT. The manipulator is supposed to be able to handle with specimens in so-called preparation chamber, which the specimens are put in before placing into the analytic chamber. In the preparation chamber the surface finishing and also other operations are made. In the theoretical part some of the technologies used in vacuum engineering, especially various principles of pressure measurement and gas pumping, are described. Besides, the thesis is focused on a brief description of UHV SEM being developed and the methods of specimen preparation. The practical part deals with the concept and the mechanical design of manipulator itself.
|
|
|
Preparation of SiN ultrathin films
Dvořák, Martin ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This bachelor´s thesis deals with design, testing and calibration of an effussion cell generating silicon atomic beam having thermal energy (0,1 - 1 eV). These beams are used for the preparation of Si and SiN ultrathin films. Silicon nitride and its applications in semiconductor industry are reviewed. First experiments with deposition of ultrathin films of Si and SiN are described. These layers have been analyzed by x-ray photoelectron spektroscopy (XPS) and atomic force microscopy (AFM).
|
|
|
Design and Construction of an Effusion Cell for Growth of Ultrathin Layers
Křápek, Ondřej ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This Bachelor's work deals with the design, documentation and construction of effusion cell for deposition of ultrathin layers of various materials in conditions of ultrahigh vacuum. After fabrication and assemblage the effusion cell was placed to an ultrahigh vacuum chamber (p ~ 10-5 Pa) where the first testing deposition of a silver ultrathin film on Si (111) substrate was performed. This sample was studied by X-ray photoelectron spectroscopy and atomic force microscopy.
|
|
|
Sequential growth of GaN nanocrystals on SiO2 substrate modified by FIB method
Flajšmanová, Jana ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This bachelor's thesis deals with the selective growth of gallium (Ga) and gallium nitride (GaN). In theoretical part, there is a brief description of growth of ultrathin films with respect to GaN and their manufacturing. Experimental part is aimed to the deposition of Ga and GaN on silicon substrates Si(1 1 1). Substrates with the native silicon dioxide layer (SiO2) were modified by focused ion beam (FIB). GaN was deposited by pulsed deposition followed by postnitridation. Prepared samples were studied by atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM).
|
|
|
Testing of the new UHV scanning electron microscope and design of its effusion cel
Šárközi, Rudolf ; Mach, Jindřich (referee) ; Bábor, Petr (advisor)
This work focus on the development and the design of the effusion cell that is able to deposit different materials in downward orientation. The Cell itself should be placed into the ultra-vacuum microscope (UHV-SEM) developed in TESCAN company in the collaboration with Institute of Physical Engineering. Theoretical part is devoted to the description of the electron microscope and its, in the future installed, parts, which will be used for the preparation and the analysis of the nanostructures. In this work, the first measurements with the electron microscope are presented, and the influence of mechanical vibrations to image quality is discussed.
|
|
| |
|
|
Growth of ZnO nanowires
Mikula, Martin ; Voborný, Stanislav (referee) ; Kolíbal, Miroslav (advisor)
In this thesis the most important properties of nanowires are briefly characterized and possible methods of their synthesis are described. Special attention is paid to zinc oxide nanostructures as well as VLS mechanism, which is crucial for explanation of nanowire growth. Furthermore, deposition chamber for growth of ZnO nanowires has been assembled and effusion cell for zinc has been tested. Testing of the cell revealed one major drawback of its design, which prevents its use for zinc deposition. Therefore, no growth of ZnO nanowires has been carried out and before it can be accomplished, the effusion cell has to be modified.
|
guest ::
