Copper has become the metal of choice for metallization, owing to its high electrical and thermal conductivity, relatively higher melting temperature and correspondingly lower rate of diffusivity. Most of the current studies can get high strength copper thin films but on an expense of conductivity. This study proposes a technique to deposit high strength and high conductivity copper thin films on different silicon substrates at room temperature. Single crystal Cu (100) and Cu (111) have been grown on Si (100) and Si (110) substrates, respectively. Single crystal Cu (111) films have a high density of growth twins, oriented parallel to the substrate surface due to low twin boundary energy and a high deposition rate. The yield strengths of these twinned Cu films are much higher than that of bulk copper, with an electrical resistivity value close to that of bulk copper. X-ray diffraction, transmission electron microscopy and nanoindentation techniques were used to show that high density twins are sole reason for the increase in hardness of these thin films. The formation of growth twins and their roles in enhancing the mechanical strength of Cu films while maintaining low resistivity are discussed.

Abstract Recently, a-Si:H TFT based liquid-crystal display has encroached on the territory of the cathode ray tubes. There is a tendency to fabricate the active matrix LCD on the plastic or flexible substrates. Instead of glass, flexible substrates will make the application of TFT-LCD extensive due to the several advantages: i.e. ultra-slim, light-weight and unbreakable, etc. Nevertheless, the limitation of process temperature for the low-melting substrates is an important issue. In this thesis, the feasibility of a-Si TFT devices fabricated on flexible substrates by using two different technologies have been evaluated. First, a-Si TFT devices were fabricated on glass at 150¢Jsuccessfully and the characteristics of films deposited at lowtemperature have been studied sequentially. For improving the adhesion between organic and inorganic layers and protecting substrate against water or gas during processes, several hot coating layers were investigated. With hot coating layer be introduced, glass was substituted by plastic substrates. We chose PES as the flexible substrate from several candidates due to better optical transmittance and good thermal stability below 200¢J. After direct fabrication on flexible substrate, the stability of electronic characteristics were been investigated with bending examination. In addition, TFT devices were successfully separated from glass and transferred to flexible substrates such as PES or metal foil. Using this technology, temperature limitation has been circumvented and TFT devices still exhibit good electronic characteristic. Furthermore, the bending measurements have been also applied to devices.

Aliphatic polyesters prepared by the ring opening polymerization of lactones and lactides, are versatile polymers having good hydrolyzability, mechanical properties and biocompatibility. These characteristics make them a leading material in biomedical and pharmaceutical industries as a resorbable implant and a vehicle for controlled drug delivery. An extensive research effort has been made to develop new initiators, catalysts for the ring opening polymerization of cyclic esters. Many effective initiators based on alkali metals, metal oxides have been developed for anionic polymerization of lactones. The main objectives of this project were to develop a novel catalyst by utilizing fully biocompatible and non-toxic reagents for the synthesis of polycaprolactone (PCL) by ring opening polymerization of cyclic esters at reasonably low temperature and a synthesis of hybrid silica nano-composite for biomedical applications and its characterization. Silica and dry calcium hydride reagents were used to successfully prepare heterogeneous catalysts for the ring opening polymerization of cyclic ester monomer å-caprolactone at reasonably low temperature of 100 oC. Two kinds of catalyst were prepared with non-functionalized and silane functionalized silica. The GP silane functionalized silica catalyst showed higher activity and higher product yield as compared to non-functionalized catalyst during polymerization at the same temperature. The in-situ polymerization kinetics of both reactions was studied using Raman spectroscopy. A silica based nano-composite was also synthesized which has a potential application in bone tissue engineering and possible drug delivery. The synthesized polyester and hybrid silica nano-composite were characterized with different analytical techniques to confirm required product formation.

The oleaginous yeasts have an ability to accumulate an increased number of lipids, under certain circumstances. These microbial lipids differentiate in the number of fat acids present, which enables their wide application in biotechnological industry. This master’s thesis is aimed on lipid production, number of the fat acid groups present, and squalene production by Metschnikowia yeasts, based on the cultivating conditions. Biomass and lipid production was observed in separate cultivation media, with the addition of the different waste substrates. Production properties were observed by method of the gas chromatography. For the squalene production observation, a HLPC method was chosen. All production groups were able to accumulate lipids on the waste substrate, although in different values. These values were very individual, especially in the areas of the specific groups and growth on the given substrate. The lipid composition was different, which was caused by differences in the waste substrates. With regards to the squalene production – the yeasts from the Metschnikowia family were not able to produce squalene in the presence of the terbinafine and its increasing concentration. Therefore, the same procedure was chosen, as it was for the Yarrowia lipolytica yeast, with the difference in the sterol synthesis, however squalene was still not produced this way.

This thesis was focused on study of biotechnological utilization of waste substrates to produce lipids by yeast of the genus Metschnikowia. Waste materials and their subsequent transformation into high value-added products such as microbial lipids are currently considered as an alternative source for biofuel production. Therefore, the experimental part was aimed at investigating the influence of a carbon source to the controlled overproduction of lipids by yeast Metschnikowia. Total of 12 yeast strains of the genus Metschnikowia were selected. Yeast strains M. pulcherrima , M. pulcherrima 147, M. pulcherrima 149, M. andauensis 129 a M. fructicola 15 were purchased from Culture Collection of Yeasts (CCY, Bratislava, Slovakia). The growth characteristics of this yeast strains were also studied. It may serve to better understanding of the physiology of the yeast strains and also to help in further analysis of the produced metabolites. The other strains M. chrysoperlae 1158, M. pulcherrima 1232, M. fructicola 1235, M. andauensis 1241, M. sinensis 1244, M. zizyphicola 1247 a M. shanxiensis 1250 were purchased from CBS (Centraalbureau voor Schimmelcultures, Utrecht, the Netherlands).Yeast strains were cultivated on crude animal fat, glycerol and cheese whey under conditions of different C/N ratios. Because of higher lipid yields, cultivation was carried out at 14°C for 14 days. The accumulated lipid content was determined by gas chromatography and Raman spectroscopy. The glycerol-containing medium was evaluated as the most suitable for microbial lipids production. The total amount of lipids present in cells of M. pulcherrima 1232 was 36,31%. At the same time, quantitative screening of lipase enzymatic activity in Metschnikowia yeast was performed using spectrophotometric method with p-NPP. Controlled production of lipolytic enzymes has been monitored by using two types of media: crude animal fat and crude animal fat with addition of emulsifier (Tween 80). The conclusion of the work was supplemented by analysis of the karyotype of yeasts of the genus Metschnikowia using the technique of pulsed gel electrophoresis.

Carotenoids are naturally occurring pigments of plants also produced by microbes. The area of their application concerns mainly food industry; however, they are used in chemical, pharmaceutical, and cosmetics industry as well. Currently, the isolation of carotenoids from plants is markedly regulated by legislation, so the study of their production is greatly emphasised, where the microbiological, instead of the synthetic, production of carotenoids is being prioritized. This work was made as a comparative study of carotenogenic yeasts of the genes Rhodotorula, Sporobolomyces, and Cystofilobasidium. Their ability to use various waste substrates as a carbon and nitrogen source and source of other nutrition factors was tested. In this work, conditions of random mutagenesis were optimized. Particular yeast strains were also subjected to the effect of mutagen ethyl methanesulfonate (EMS) in order to increase the production of biomass and specific metabolites – carotenoids and other lipid-soluble substances. Random mutagenesis and mutant strain selection was performed using waste subtrates as glycerol, pasta and some pasta hydrolyzed by fungal extracellular enzymes. Subsequently, a control of specific DNA sequences in pigments overproducing mutants was analyzed by PCR/DGGE (denaturating gradient gel electrophoresis). Increased production of -carotene was achieved in a mutant of Sporobolomyces roseus strain growing on glycerol, pasta, and hydrolyzed pasta. Overproduction of carotenoids by mutant strain of Rhodotorula glutinis was observed in glucose medium only. Mutants of Cystofilobasidium capitatum exhibited a decrease of biomass production; on the other hand, the production of carotenoids increased especially in pasta medium hydrolyzed by enzyme preparative from Fusarium solani. In this work it was confirmed that using random mutagenesis strains capable to utilize waste substrates can be selected. In mutant strains increased carotenoids biosynthesis was observed, which enables effective use of cheap substrates and reduction of the negative effects of wastes on the environment.

Growth of Corbicula fluminea was monitored in the laboratory. Three experiments were conducted. Experiment I utilized three substrates and one food type. Experiment II utilized three substrates and two food types. Experiments I and II were conducted to determine if substrate type or food type effected growth. Experiment III used no substrates, one food type and was conducted to determine growth response to different types of water. Clams were maintained in three substrates: sand, gravel and clay. Clams were also maintained without substrate. Growth was monitored by measuring shell length (mm) and recording the weight (mg) of clams over a period of thirty days. At the end of the test period data were evaluated for normality and homogeneity.

Flexible electronics have gained great attention recently. Applications such as flexible displays, artificial skin and health monitoring devices are a few examples of this technology. Looking closely at the components of these devices, although MEMS actuators and sensors can play critical role to extend the application areas of flexible electronics, fabricating movable MEMS devices on flexible substrates is highly challenging. Therefore, this thesis reports a process for fabricating free standing and movable MEMS devices on flexible silicon substrates; MEMS flexure thermal actuators have been fabricated to illustrate the viability of the process. Flexure thermal actuators consist of two arms: a thin hot arm and a wide cold arm separated by a small air gap; the arms are anchored to the substrate from one end and connected to each other from the other end. The actuator design has been modified by adding etch holes in the anchors to suit the process of releasing a thin layer of silicon from the bulk silicon substrate. Selecting materials that are compatible with the release process was challenging. Moreover, difficulties were faced in the fabrication process development; for example, the structural layer of the devices was partially etched during silicon release although it was protected by aluminum oxide which is not attacked by the releasing gas . Furthermore, the thin arm of the thermal actuator was thinned during the fabrication process but optimizing the patterning and etching steps of the structural layer successfully solved this problem. Simulation was carried out to compare the performance of the original and the modified designs for the thermal actuators and to study stress and temperature distribution across a device. A fabricated thermal actuator with a 250 μm long hot arm and a 225 μm long cold arm separated by a 3 μm gap produced a deflection of 3 μm before silicon release, however, the fabrication process must be optimized to obtain fully functioning devices on flexible silicon.

Gas source molecular beam epitaxy (GSMBE) has been used to grow InGaAs/lnP epitaxial layers in selected areas defined by SiO2-masked InP substrates, with the goal of obtaining controlled in-plane variations in the bandgap of the InGaAs wells. The ability to alter the bandgap of the semiconductor spatially over the surface in one growth procedure is desirable for integrating laser, waveguide and detector devices. To form the masked substrates, stripes (ranging in width from 2 pm to 50 pm) were opened up in SiO2 by standard photolithography. The crystal growths were carried out at various substrate temperatures (ranging from 460 °C to 510 °C) and arsenic fluxes (V/lll ratios ranging from 1.2 to 3.4). The properties of the epitaxial layers were investigated by using such analytical techniques as photoluminescence, electroluminescence and transmission electron microscopy (TEM). Photoluminescence measurements performed on waveguide stripes of decreasing width reveal an increasing red-shift of the e1-hh1 transition in InGaAs wells. The maximum red-shift occurred when growing at a high substrate temperature and a low arsenic flux. For example, a decrease in slit width from 50 pm to 10 pm resulted in a 25 meV shift of the photoluminescence peak. From cross-sectional TEM measurements, the wavelength shift observed can be attributed primarily to an increase in thickness of the InGaAs well, due to incorporation of additional indium and gallium migrating from the material on the masked regions. The interfaces in the centre of the stripe region are defect free; however, stacking faults and thickness variations are evident 1-2 pm from the edges. These results are confirmed by scanning photoluminescence, in which the maximum intensity occurs at the centre of the stripe and decreases to zero at the edges. Mapping of the peak wavelength across the stripe reveals a diffusion profile, with the edges being additionally red shifted by 10 nm. Reactive ion etching of the edge and the polycrystalline material results in a much improved spectral photoluminescence scan, in both increased intensity of the bandgap peak and elimination of lower energy peaks assumed to be correlated with edge effects. Finally, a stripe contact light emitting device, with a single 50 A quantum well InGaAs/lnP structure, was fabricated and electrically pumped. The device exhibited spectral peak wavelength shifts between narrow stripes (10 pm) and wide stripes (50 pm) of 22 nm, similar to the value observed by photoluminescence studies. / Thesis / Master of Engineering (ME)

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