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Original title in Czech: Fyzikální elektronika a nanotechnologieFEKTAbbreviation: PP-FENAcad. year: 2014/2015
Programme: Electrical Engineering and Communication
Length of Study:
Profile
The objective of the study is to provide PhD education to MSc graduates in all partial fields and to create a cross-disciplinary overview of the present development, to develop theoretical foundations in the selected research area, to master the methods of scientific, to develop their creative abilities and to use them for the solution of research problems. This all should lead to a dissertation thesis, which will provide an original a significant contribution to the research status in the field of interest.
Key learning outcomes
Graduates of this program will acquire cross-disciplinary knowledge of and experience in technical and physical subjects on a high-quality theoretical level. Graduates are for their later independent research and development work equipped with the knowledge and experience from, in particular, physics of semiconductors, quantum electronics and mathematical modeling and will be able to independently solve problems associated with nanotechnologies. Potential job careers: research worker in basic or applied research and in the introduction, implementation and application of new prospective and economically beneficial procedures and processes in the field of electronics, electrical engineering, non-destructive testing and reliability and material analysis.
Occupational profiles of graduates with examples
Graduates of this program will acquire cross-disciplinary knowledge of and experience in technical and physical subjects on a high-quality theoretical level. Graduates are for their later independent research and development work equipped with the knowledge and experience from, in particular, physics of semiconductors, quantum electronics and mathematical modeling and will be able to independently solve problems associated with nanotechnologies. Potential job careers: research worker in basic or applied research and in the introduction, implementation and application of new prospective and economically beneficial procedures and processes in the field of electronics, electrical engineering, non-destructive testing and reliability and material analysis
Guarantor
prof. RNDr. Pavel Tománek, CSc.
Issued topics of Doctoral Study Program
An important role in many plasma processing devices plays the radiative heat transport. The experimental investigation is very difficult, therefore, mathematical modeling is of great imporatnce. The knowledge of absorption properties of the plasma is necessary for succesfulI theoretical modeling. The aim of this disertation work is to collect atomic and molecular data which will serve as input data for calculation of absroption coefficients of selected plasmas. It concerns searching of data in available web databases, their computer processing, and creation of own databases in the form of input files for further calculations.
Supervisor: Bartlová Milada, doc. RNDr., Ph.D.
A large number of inhomogeneities and defects appear in solar cells during their manufacturing due to their large surface area. They reduce quality of cells and cause decrease of their efficiency during operation in solar panels. The aim of the work will be measurement and analysis of these solar cell loss-making mechanisms both at edges and in the volume of samples by monitoring of their activities during electrical or optical excitation. The study will be mainly focused on the characteristics of radiation emitted in the forward and reverse direction during electrical excitation (spectroscopy in the visible region by a CCD camera, infrared spectroscopy, a thermo camera), current fluctuations during voltage loading, local study of surface properties (LBIC, electron microscopy) and other characteristics. The description of different types of loss-making mechanisms in silicon solar cells and their effect on the efficiency of solar cells and panels will be proposed on the basis of this study. The Ph.D. student will cooperate on the research projects SIX (Sensor, Information and Communication Systems) and CEITEC (Central European Institute of Technology).
Supervisor: Koktavý Pavel, prof. Ing., CSc. Ph.D.
Thesis deals with a study of elctronic noise in order to develop a non-traditional technique for evaluation of output sensor signal considering direct component and also its fluctuation. Due to stochastic nature of the matter, physical processes in materials are considered to be stochastic, and they reveal as fluctuation of measurable quantities macroscopically, i.e noise. Motivation is not only increase of selectivity and sensitivity but also possibility of electronic noise development. The aim is to analyze dependencies of these fluctuations on input quantity by measurements of noise characteristics (spectral density of noise current) and transport characteristics.
Supervisor: Sedlák Petr, doc. Ing., Ph.D.
Fiber-optic sensors offers wide spectrum of applications nowadays. These sensors have such advantages as lightweight, avoidance of ground loops, capability of responding to a wide range of measurands, resistance to chemical corrosion, high temperature, high sensitivity, large bandwidth, and immunity to electromagnetic interference. Thus fiber-optic sensors are used as accelerometers, thermometers, humidity sensors, chemical and biochemical sensors. Theme of the thesis focuses on an usage of the sensors for material diagnostics and structure health monitoring. The aim of the work is to develop and to implement an optic system, which would serve, e.g. for detection of partial discharges in power transformers.
Subject of doctoral thesis will be non-destructive study of defect regions in the structure of perspective Cu(InGa)Se2 thin-film solar cells. These heterojunction materials have a very high absorption coefficient and the associated conversion efficiency of optical energy. The total thickness of the functional structure is about 3 µm and it is very sensitive to the presence of local and bulk defects reducing efficiency and lifetime. By studying of these defects can be pointed out valuable information about loss mechanisms, electric charge transport phenomena and technological precaution can be proposed for their elimination. For diagnostics purposes will be used several methods such as monitoring of radiation by means of infrared and CCD camera, response monitoring to local irradiation, the microscopic study of surface topography, specific surface modification by ion beam and measuring of voltage or current fluctuations. Cooperation with producers of thin-film solar cells is planned in, for which the research is very attractive. In addition, thin-film solar cells producers are highly involved in non-destructive research and we are planning intensive cooperation.
Supervisor: Grmela Lubomír, prof. Ing., CSc.
The main problem in the process of the solar cell conversion efficiency and service life improving is to find their basic parameters. A lot of methods exist for this purpose but they often give different results. The goal of the work will be research of advanced modern methods for important parameters finding for example quantum efficiency, minority charge carrier lifetime, impact ionization coefficients or impurities concentration profiles in PN junctions and others. Obtained results will be used for these parameters measuring for some types of solar cells, primarily monocrystalline, polycrystalline and amorphous Si solar cells and CIGS cells. The Ph.D. student will cooperate on the research projects SIX (Sensor, Information and Communication Systems) and CEITEC (Central European Institute of Technology).
Radiation energy transfer influences significantly physical processes occuring in the plasma, it plays important role in many devices in plasma processing devices. Electric arc plasmas are utilized in number of industrial applications, e.g. in plasma metallurgy, waste treatment, plasma cutting, welding or spraying. The goal of the work is to solve the equation of radiation transfer by means of the approximate method of discrete ordinates (SN-approximation), to compare the obtained results of radiation energy and radiation flux for selected kinds of plasmas with known results obtained by other approximate methods (method of partial characteristics, diffusion approximation), to discuss availability of different approximate methods.
The aim of this project is to determine parameters of traps in insulation layer of HFET/HEMT structures by analysis of its noise characteristics, mainly RTS (random telegraph signal) noise. Experimental work is based on measurement of temperature dependence of noise using helium cryostat and study of amplitude and mean time of capture and emission as a function of electric field intensity and charge carrier concentration in channel. These results will be used to improve generation-recombination model of noise origin and localization of traps.
Supervisor: Pavelka Jan, doc. Mgr., CSc. Ph.D.
Thesis deals with a study of electromagnetic emission (EME) signals and description of their features in order to experimental study of degradation processes, leading to total destruction of model specimens under mechanical loading, and localization of these processes. EME signals are of stochastic nature and are processed by similar principles as those, which are used in speech recognition. Motivation is an exact evaluation of materiál behavior under test. Aim of the work is determination of appropriate signal features of emission events in time domain, frequency domain and time-frequency domain.
The subject of the research will be the studies of the properties of nanocomposites for electrical insulating products for high-voltage applications, e.g. instrument transformers and sensors These materials are used for electrical insulating compounds based on epoxy resins. The objective of the iresearch work will be the implementation of nanoparticles into electrical insulating compounds with the aim to improve their properties, in particular their electric breakdown strength and ability to withstand partial discharges and electric treeing and to reduce their dielectric losses.
Supervisor: Liedermann Karel, doc. Ing., CSc.
Decreasing the dimensions in integrated circuits (currently 32 nm) brings about an increase of interconnect capacitance and thus the reduction of the signal propagation speed. The limiting factor for a further improvement of electronic device performance thus become not the properties of semiconductor devices themselves but rather interconnect delays and, hence, too, high magnitudes of parasitic capacitances. One of the options for the reduction of interconnect capacitances is the reduction of the permittivity (dielectric constant, k) of thin-layer insulating layers (capacitance is directly proportional to permitivity). Two major routes are available: replacement of polar Si-O bonds with less polar Si-F or Si-C bonds or raising the porosity (intentional introduction of air voids). The newly developed low-k materials must, however, not limit the currently used silicon technologies and must be able to pass all manufacturing steps (temperatures up to about 1100°C). The work on this topic will require experimental work in sample preparation and design, studies of the theory of low-k dielectrics and the measurement of electrical properties of developed material systems. What is available: measurement equipment for the frequency range 10-3 – 109 Hz and Janis helium cryostat CCS-400/204 for the temperature range 10 – 500 K. Purchased, yet not operated are Novocontrol ALPHA-AT high-resolution high-frequency analyzer with frequency range 3 μHz – 40 MHz and Nicolet 8700 FTIR-spectrometer with wave number range 20 000 – 350 cm-1.
The subject of the research will be dielectric properties of nanocomposites for electrical insulation. These materials are based on thermosetting resins, mostly epoxides, containing finely dispersed SiO2, TiO2, Al2O3 or WO3 microfillers and nanofillers, eventually more complex chemical formulations. The presence of nanoparticles with dimensions of some 10 – 20 nm favorably affects the withstand capability of nanocomposites to partial discharges and electrical treeing and, hence, the breakdown strength as well as the degradation resistance. This in turn brings the possibility to manufacture electrical equipment (e.g. switchgear, vacuum interrupters) with smaller dimensions and weight and improved reliability. An important issue concerning all nanocomposites is the presence of a large number of interfaces. They are to due to the presence of nanoparticles with complex shapes (neither planar nor spherical). These interfaces exhibit a low stability, which may later cause substantial changes of electrical properties in the course of ageing. One of the objectives of the proposed research would therefore be to study the behavior of nanocomposites in the course of accelerated ageing. The work on this topic will require experimental work in sample preparation and design, studies of the relation between microphysical structure and electrical properties and the measurement of electrical properties of developed material systems. Equipment currently available in the Department of Physics: measurement equipment for the frequency range 102 – 109 Hz and Janis helium cryostat CCS-400/204 for the temperature range 10 – 500 K, as well as established software for measurement control. Purchased, yet not operated are Novocontrol ALPHA-AT high-resolution high-frequency analyzer with frequency range 3 μHz – 40 MHz and Nicolet 8700 FTIR-spectrometer with wave number range 20 000 – 350 cm-1.
The objective of the research is the investigation of electrical properties of CCTO ceramics (i.e., based on CaCu3Ti4O12), doped with transition metals and lanthanides. Attention will be focused toward the identification of mechanisms leading to high dielectric constant (permittivity) of the order 104 – 105 and, subsequently, on the modification of CCTO ceramics formulation in order to reduce dielectric loss and to extend the frequency interval, in which the dielectric constant retains its high value, up to the GHz range Materials exhibiting high permittivity are needed for new applications, particularly in integrated circuits and in capacitors. In capacitors, high-k dielectrics are used in order to attain higher energy densities and thus to reduce the size of capacitors themselves. The work on this topic will require experimental work in sample preparation and design, studies of the theory of high -k dielectrics and the measurement of electrical properties of developed material systems. What is available: measurement equipment for the frequency range 102 – 109 Hz and Janis helium cryostat CCS-400/204 for the temperature range 10 – 500 K. Purchased, yet not operated are Novocontrol ALPHA-AT high-resolution high-frequency analyzer with frequency range 3 μHz – 40 MHz and Nicolet 8700 FTIR-spectrometer with wave number range 20 000 – 350 cm-1.
Micro-cracks creation in mechanical loaded solids is accompanied by origin of electromagnetic (EME) and acoustic (AE) signals. These signals may be used for study of micro-cracks formation evolution, their characteristics finding and their localization. EME and AE methods are usable in electrical engineering, mechanical engineering, civil engineering or in geophysics. The goal will be determination of micro-cracks primary parameters and their localization in concrete, granite and in modern composite materials for structural applications. Analysis of EME and AE signals origin and propagation will be performed in these materials and models will be suggested. The methodology for determination of selected primary parameters and micro-cracks localization will be suggested and verified. The solution of hydraulic press control via PC and realization of automated set-up will be an important part of the work. The Ph.D. student will cooperate on the research projects SIX (Sensor, Information and Communication Systems) and CEITEC (Central European Institute of Technology).
Supercapacitors are used as peak power sources mostly in automobile industry and space applications. Expected life time of components in space applications is 10 years at least. Long term reliability estimation is in the meantime based on the monitoring of the electrical parameters change after the accelerated life tests. The components passing the tests with parameters values in the given limits are certified for the further use. It can be supposed, that the accelerated life tests create additional defects in the studied structures. Within the PhD. work the analysis of the ageing influence on the supercapacitor structure will be performed and the reliability indicators for the estimation of the quality and reliability of supercapacitors will be proposed.
Supervisor: Sedláková Vlasta, doc. Ing., Ph.D.