This diploma thesis discusses the gas sensor preparation via anodic oxidation. It names sensor types, deals with the sensing principle of electrochemical sensors in detail and submits sensor parameters. It describes preparation technology and characterization technology methods. In the experimental part, it focuses on both the measurement methodology and the electrochemical oxygen sensor covered with titanium dioxide nanocolumns fabrication. Not the least it discusses acquired research results.

This work deals with the preparation of gold nanostructures for future usage in electrochemical sensors and biosensors, methods for their characterization and production. The emphasis is focused on the template-based electrodeposition method of gold and on study of the effect of manufacturing conditions on physical properties, mainly electrical and topological of nanostructures. Thesis is focused also on overall function and sensitivity of the gold nanostructured electrode.

This thesis deals with the study of cells on nanostructured surfaces of titanium dioxide, which are produced by the electrochemical method called anodic oxidation. The theoretical part is formed by an overview of manufacturing nanostructured surfaces using anodic oxidation method. It mentions the influence of external factors on the geometric parameters of the structure and description of methods of characterization structures. Furthermore there is processed outline of use for biomedical application and the description of interaction of the cell with surface. The practical part includes description of the production of nanoporous and nano-tubular structures made on thin films of titanium by direct method of anodic oxidation on which was studied the influence of external factors. Described a procedure and production of nanorods structures and nanodots generated using alumina template (AAO) which is subsequently carried out the study of the behavior of cells, which includes tests of adhesion, examination of morphology of cells, assays of proliferation and differentiation. Structures are under investigation of the interaction of cells with the nanostructured layer compared with the smooth surface of the titanium dioxide.

Organic electronic devices are sustainable alternatives to the conventional electronics, due to their advantages of low cost, mechanical flexibility and wide range of applications. With the myriad list of organic materials available today, the opportunities to imagine new innovative devices are immense. Organic electronic devices such as OLEDs (organic light emitting diode), OPVs (Organic photovoltaics) and OFETs (organic field effect transistors) are among the leading device categories. Although OLED’s have been a huge commercial success, other categories are not lagging. Radical thinking is necessary to improve on the current performances of these devices. One such thinking is to combine the versatile ZnO (Zinc Oxide) material to organic semiconductors. This can be achieved by exploiting the dual nature of ZnO’s semiconducting and piezoelectric property. Many devices have used ZnO in combination with organic semiconductors for applications ranging from sensors, photovoltaics, OFET’s, memory and many others. The goal of the work is to incorporate the piezoelectric nature of hydrothermally grown ZnO nanowires for Opto-electronic applications. Although the initial research work was done on incorporating the piezo effect of bulk grown ZnO nanowires in improving the efficiency of an OPV, we discovered a unique memory effect in this device by incorporating ZnO nanowires in an inverted organic photovoltaic architecture. The device switched between a rectifying response in dark to resistive behavior under illumination with a finite transition time and was reversible. Since then we decided to explore few of the opto-electronic applications of this technology. The synthesis and characterization of crystalline ZnO nanowires, nanoforest and planar ZnO nanofilm are reported along with the application of these ZnO nanostructures in optoelectronic devices. Noncentro symmetry of crystalline ZnO nanostructures makes it an excellent candidate to be used as piezo functional material and these nanostructures are characterized using electrochemical cell containing ZnO electrode as the working electrode. ZnO nanostructures like nanowires, nanoforest and planar nanofilm are similarly characterized for piezo property using electrochemical technique. Different devices require distinguishing physical and electrical properties of ZnO nanostructures, hence morphology, effect of pre-strain, surface area, surface coverage and thickness of these nanostructures were evaluated for its piezoresponse. It is shown that it was possible to obtain similar piezoresponse among different ZnO nanostructures in addition to taking advantage of the structural benefits among various categories of nanostructures as per requirement. The presented research can be used as the proof-of-the-concept that ZnO nanostructures can be designed and fabricated with a prestrain to adjust the piezo response of the material under external forces. Therefore, the structure with the prestrain can be employed in various electronic and optical devices where the piezo voltage can be used for adjusting the energy band bending at an interface.

Title: SERS spectroscopy of model biomolecules for SERS biosensing Author: Martin Šubr Department: Institute of Physics of Charles University Supervisor: doc. RNDr. Marek Procházka, Dr., Institute of Physics of Charles University Abstract: The main requirement for surface enhanced Raman scattering (SERS)-based biomolecular sensing is high sensitivity and spectral reproducibility. For this purpose, ordered silver and gold nanostructures fabricated by magnetron sputtering and lithography methods at cooperating institutes were tested in this work. Reproducible SERS spectra of employed model biomolecules (amino acids, lysozyme and albumin) were obtained on ordered silver surfaces at concentrations 10-4 M - 10-6 M and as low as ≈ 10-7 M in the case of porphyrins. SERS spectra of certain biomolecules were also compared to spectra measured on silver colloid. The limit of detection provided by hydroxylamine-reduced silver colloid, using KCl as an aggregating agent, is substantially lower (on the order of 10-8 M for cysteine), but with lower spectral reproducibility. The main drawback of SERS spectra measured on silver surfaces was the occurrence of spurious bands resulting from the preparation procedure. In the case of sputter-deposited silver surfaces, it was found that keeping the substrates several hours in...

This thesis focuses on the self-assembly of the boron cluster compounds and the coassembly of metallacaborane cobalt bis(dicarbollide), COSAN, with hydrophilic polymers. The research was motivated by the discovery of HIV inhibition by COSAN and its conjugates. Therefore, we decided to study in detail the behavior of boron cluster compounds in water. We demonstrated the amphiphilic character of several boranes and carboranes by the study of surface tension and self-assembly despite the absence of classical amphiphilic topology. The behavior of COSAN showed similarities with classical surfactants, such as SDS, whereas the behavior of smaller clusters with high charge density reminded of hydrotropes or chaotropes. Furthermore, we searched for the most suitable carriers of COSAN for drug delivery. Based on the earlier findings that COSAN interacts with both poly(ethylene oxide), PEO, and poly(2-oxazoline), POX, we prepared nanoparticles by mixing COSAN with block copolymers of various types of POX. Comparing linear and star-like block copolymers, we showed that the polymer architecture has a crucial role in the morphology of nanoparticles. In addition, we proved different selectivity of alkaline cations towards PEO and POX, resulting in the different structures of nanoparticles depending on the present...

Title: Plasma polymers in the nanostructured and nanocomposite coatings Author: Artem Shelemin Department / Institute: Department of the Macromolecular Physics Supervisor of the doctoral thesis: Prof. RNDr. Hynek Biederman, DrSc. Abstract: The thesis represents the main results of my research work aimed to study nanostructured and nanocomposite films of plasma polymer. A few alternative experimental approaches were developed and investigated which ranged from low pressure (gas aggregation cluster sources and glancing angle deposition) to atmospheric pressure (dielectric barrier discharge and plasma jet) plasma processing. The metal/metal oxide Ti/TiOx, AlOx and plasma polymer SiOx(CH), Nylon 6,6 nanoparticles were prepared. The analysis of morphology of deposited plasma polymer coatings was performed by AFM and SEM. The chemical composition of films was studied by XPS and FTIR. Keywords: plasma polymer, nanoparticle, thin film, nanostructures

The present work covers investigation of the growth mechanism and growth kinetics of the ZnO nanowires and nanoneedles fabricated by using high-pressure pulsed laser deposition. The growth model based on the combination of four different flows of the interfacial particles is introduced. A variation of the free energy is given as a major reason of the change of the growth mechanism which appears by using different doped seed layers, growth temperature and the doping of the deposited material. A fabrication of the ultrathin nanowires with a diameter of d < 10 nm at CMOS compatible growth temperature of T = 400°C is demonstrated. The diameter of these nanowires is comparable with the Bohr radius. The growth of the Al and Ga doped and undoped ZnO nanoneedles with a sharp tip was shown. The doping of the nanowires and nanoneedles can be promising for their applications. By using a patterned sapphire substrate, an unidirectional growth of the nanowires and nanoneedles was achieved. These nanostructures are tilted by 58°ZnO with respect to the surface normal.:Bibliographic Record Contents 1 Introduction I Basics and Methods 2 Basic properties and growth concept 2.1 ZnO nanowires and nanoneedles 2.1.1 Applications 2.2 Nanowire and nanoneedle fabrication 2.2.1 Growth mechanisms which require a catalyst 2.2.2 Catalyst-free epitaxial growth mechanism 2.3 Free energy and the growth mechanism 2.4 NW growth techniques 2.5 Aligned tilted growth 3 Growth and characterization 3.1 Preparation of the seed layers by CVD 3.2 Preparation of the seed layers by low pressure PLD 3.3 HP PLD for the NW and NN growth 3.4 Characterization techniques 3.4.1 X-ray Diffraction 3.4.2 Atomic Force Microscopy 3.4.3 Scanning electron microscopy 3.4.4 Energy Dispersive X-ray Spectroscopy 3.4.5 Spectroscopic Ellipsometry 3.4.6 Cathodoluminescence 3.4.7 Angle-varied X-ray photoelectron spectroscopy 3.4.8 Etching of the seed layers 4 Seed layer characterization 4.1 Doping concentration 4.2 Surface morphology 4.3 Crystalline quality 4.4 Surface polarity 4.5 Summary of the Chapter II NW growth: results 5 NW growth characteristics 5.1 Material free energy and the deposited material parameters 5.2 Growth kinetics 5.3 Summary of the Chapter 6 NW growth on doped seed layers 6.1 Al doped seed layers 6.2 NW growth on Ga doped seed layers 6.3 Optical characteristics of the ZnO NWs 6.4 Summary of the Chapter 7 Growth of ZnO(Al) and ZnO(Ga) NWs 7.1 Al-doped ZnO NWs grown on ZnO(Al) seed layers 7.2 Ga-doped ZnO NWs grown on ZnO(Ga) seed layers 7.3 Summary of the Chapter 8 Growth of tilted ZnO NWs and NNs 8.1 Patterning of the substrates . 8.2 Growth of tilted NNs 8.3 Growth of tilted NWs 8.4 Optical properties of the tilted nanostructures 8.5 Summary of the Chapter 9 Summary and outloock 9.1 Summary 9.2 Outlook Acknowledgements Curriculum Vitae List of own Articles List of own Conference Talks and Posters References

The main goal of this work is to search for new stable porous carbon-based materials, which have the ability to accommodate and store hydrogen gas. Theoretical and experimental studies suggest a close relation between the nano-scale structure of the material and its storage capacity. In order to design materials with a high storage capacity, a compromise between the size and the shape of the nanopores must be considered. Therefore, a number of different carbon-based materials have been investigated: carbon foams, dislocated graphite, graphite intercalated by C60 molecules, and metal-organic frameworks. The structures of interest include experimentally well-known as well as hypothetical systems. The studies were focused on the determination of important properties and special features, which may result in high storage capacities. Although the variety of possible pure carbon structures and metal-organic frameworks is almost infinite, the materials described in this work possess the main structural characteristics, which are important for gas storage.

In this work I investigate the expulsion of carriers from nanostructures using the double-barrier quantum well (DBQW) as an example and discuss manifestations of this effect in the spectrum of the DBQW in absence of bias, and in the tunneling current in presence of bias. Assuming equality of the Fermi energy in all regions of the considered system, I compute the relative density of carriers localized in the DBQW and conclude that a fraction of carriers is expelled from this nanostructure.