Characterisation of Nanostructure Deposited by PVD and CVD Technology

Disertační práce se zabývá mechanickými vlastnostmi tenkých otěru odolných tvrdých vrstev. Představuje metodu dynamického testování tenkých tvrdých vrstev na nově zkonstruovaném prototypu dynamického měřiče otěru. Přináší srovnání se standardními metodami zkoušení vrstev a doplňuje je o nové experimentální výsledky dynamických testů vrstev. V neposlední řadě se zabývá preparačními technikami vrstvových systémů nanesených na různé podložky a jejich charakterizace pomocí optické a elektronové mikroskopie.The thesis deals with mechanical properties of thin hard wear-resistant coatings. The work presents a method of dynamic testing of thin hard coatings on a newly constructed prototype of impact wear tester. It provides a comparison with standard methods of layer testing and presents new experimental results of dynamic impact wear test of the coatings. Finally, the thesis covers preparation techniques of thin film systems deposited on various substrates and their characterization using optical and electron microscopy.

Characterization of ultra-thin tungsten layers

Atomic force microscopy and surface resistivity measurement were used for characterization of ultra-thin tungsten layers deposited on purified silicon with 200 nm thermic silicon dioxide substrate. Radio-frequency magnetron sputtering was used for tungsten deposition. © Research India Publications

Nanoscale Estimation of Coating Thickness on Substrates via Standardless BSE Detector Calibration

The thickness of electron transparent samples can be measured in an electron microscope using several imaging techniques like electron energy loss spectroscopy (EELS) or quantitative scanning transmission electron microscopy (STEM). We extrapolate this method for using a back-scattered electron (BSE) detector in the scanning electron microscope (SEM). This brings the opportunity to measure the thickness not just of the electron transparent samples on TEM mesh grids, but, in addition, also the thickness of thin films on substrates. Nevertheless, the geometry of the microscope and the BSE detector poses a problem with precise calibration of the detector. We present a simple method which can be used for such a type of detector calibration that allows absolute (standardless) measurement of thickness, together with a proof of the method on test samples

Thermal tuning of spectral emission from optically trapped liquid-crystal droplet resonators

Surfactant-stabilized emulsion droplets of liquid crystals (LCs) suspended in water and labeled with a fluorescent dye form active, anisotropic optofluidic microresonators. These microresonators can host whispering gallery modes (WGMs), high-quality morphology-dependent optical resonances that are supported due to the contrast of refractive index between the LC droplets and the surrounding aqueous medium. In addition, owing to the refractive index contrast, such LC emulsion droplets can be stably trapped in three dimensions using optical tweezers, enabling long-term investigation of their spectral characteristics. We explore various combinations of fluorescently dyed LC droplets and host liquid-surfactant systems and show that the WGM emission spectra of optical resonators based on optically trapped LC emulsion droplets can be largely and (almost) reversibly tuned by controlled changes of the ambient temperature. Depending on the actual range of temperature modulation and LC phase of the studied droplet, thermally induced effects can either lead to phase transitions in the LC droplets or cause modifications of their refractive index profile without changing their LC phase. Our results indicate feasibility of this approach for creating miniature thermally tunable sources of coherent light that can be manipulated and stabilized by optical forces

One-dimensional photonic crystals with different termination layer thicknesses and very narrow Bloch surface wave and guided wave based resonances for sensing applications

We demonstrate an efficient sensing of both gaseous and aqueous analytes utilizing Bloch surface waves (BSWs) and guided waves (GWs) excited on a truncated one-dimensional photonic crystal (1DPhC) composed of six TiO2/SiO2 bilayers with a termination layer of TiO2. For the gaseous analytes, we show that 1DPhC can support the GW excited by an s-polarized wave and the theoretical shift of the resonance wavelength is linear for small changes in the analyte refractive index (RI), giving a constant RI sensitivity of 87 nm per RI unit (RIU). In addition, for the aqueous analytes, the GW excited by s-polarized and BSW by p-polarized waves can be resolved and exploited for sensing applications. We compare two designed and realized 1DPhCs with termination layer thicknesses of 60 nm and 50 nm, respectively, and show experimentally the differences in their very narrow reflectance and phase responses. An RI sensitivity and figure of merit as high as 544.3 nm/RIU and 303 RIU-1, respectively, are obtained for the smaller thickness when both s- and p-polarized BSWs are excited. This is the first demonstration of both very deep BSW-based resonances in two orthogonal polarizations and a very narrow resonance in one of them.Web of Science98art. no. 56

Nanostructures for Achieving Selective Properties of a Thermophotovoltaic Emitter

This paper focuses on the research and development of a suitable method for creating a selective emitter for the visible and near-infrared region to be able to work optimally together with silicon photovoltaic cells in a thermophotovoltaic system. The aim was to develop a new method to create very fine structures beyond the conventional standard (nanostructures), which will increase the emissivity of the base material for it to match the needs of a selective emitter for the VIS and NIR region. Available methods were used to create the nanostructures, from which we eliminated all unsuitable methods; for the selected method, we established the optimal procedure and parameters for their creation. The development of the emitter nanostructures included the necessary substrate pretreatments, where great emphasis was placed on material purity and surface roughness. Tungsten was purposely chosen as the main material for the formation of the nanostructures; we verified the effect of the formed structure on the resulting emissivity. This work presents a new method for the formation of nanostructures, which are not commonly formed in such fineness; by this, it opens the way to new possibilities for achieving the desired selectivity of the thermophotovoltaic emitter

SMV-2019-16: Deposition technology and implementation of EUV multilayer system

We have developed deposition technology and implementation of multilayer systems of Mg/Si or molybdenum and silicon prepared by magnetron sputtering. Interface roughness has to be smaller than 0.1 nm and reproducibility of bilayer thickness (i.e. molybdenum or Mg and silicon) must be better that 0.1 nm. This multilayer system was used as a EUV mirror

Tribologické chovaní tvrdých uhlíkových kompozitních vrstev

Carbon hard composite coatings were exposed to dynamical load and high temperature pin-on-disc CSM Tribometer. To evaluate the impact resistance of thin hard composite coating in dynamic loading wear applications an impact test was used. The sliding tests in air were carried out in the range from room temperature to 500 °C with controlled relative humidity. Hardness, elastic modulus and fracture toughness of deposited coatings were studied by indentation technique using Fisherscope H100 tester

SMV-2020-30: Deposition technology and implementation of layer system on high temperature polymer

We have developed deposition technology and implementation of layer systems deposited on high temperature polymer. We proved compatibility of the high temperature polymer with PVD technology we used. Sputtering requires high vacuum background pressure, it means that polymer material when heating during sputtering must not leak gases

Characterization of multicrystalline solar cells with LBIC method in different wavelength

For the determination of defects in the solar cells was used a method LBIC (Light Beam Induced Current). We use LED light source with various wavelengths to reveal the different types of defects. Using multiple wavelengths enables detecting defects in different depths. Surface defects can be observed in shorter wavelengths (400nm and 470nm). The junction region is well observed at wavelengths close to 525nm. Defects in the base material are visible using the light at a wavelength of 630nm or 890nm