1 |
Dreamhome: A Personal Space of Core Human Desire and AmbitionTanna, Hemali 1980- 14 March 2013 (has links)
Dreamhome is a creative exploration of a prototype house designed with creative freedom using possible future technologies that may not be currently feasible. New and forthcoming technology in various scientific branches that could be applicable to architecture will be presented, and the applications discussed. Limitations of application to architecture of the reviewed technologies will be discussed. Prior works by architects and engineers who push boundaries to innovatively overcome technological limitations will be explored, as will examples in which advanced technology is applied to create unique architectural designs. Together these references will evoke inspirations to be translated into an architectural design and a virtual home. The house is desired to boast of a unique design with various aesthetic and functional features that are not usually seen in present day architecture. This visualization could be a glimpse of possible home design of the future.
|
2 |
Synthesis and study of functional oxides based on earth-abundant elements / Synthèse et étude de matériaux fonctionaux à base d'éléments abondants pour des applications électroniques et optoelectronnicLiu, Hongjun 31 October 2017 (has links)
Au cours des dernières années, l'électronique à base d’oxydes métalliques a attiré de plus en plus d'attention au sein de la recherche, principalement grâce à leur potentiel en termes de réduction de coûts ainsi que la possibilité de développer une électronique transparente. Il existe plusieurs applications potentielles concernant les oxydes métalliques : le photovoltaïque, les transistors à couche mince et la photo-électrochimie. Il existe plusieurs oxydes métalliques de type n avec d'excellentes propriétés électroniques, telles que l'oxyde de zinc dopé à Al. Mais la mise au point de dispositifs entièrement à base d’oxydes métalliques est largement entravée par les mauvaises propriétés électroniques des oxydes de type p jusqu'à présent étudiés. Par conséquent, il est nécessaire de développer des matériaux semi-conducteurs d'oxyde métallique de type p présentant de meilleures propriétés électriques.Dans cette thèse, l'optimisation du dépôt de films minces de Cu2O a été effectuée par MOCVD assisté par aérosol (AA-MOCVD). Par conséquent, des films de Cu2O homogènes et de très forte cristallinité ont été déposés à basse température (environ 335 °C) sans contamination détectable de carbone. De plus, grâce à l'incorporation de l'humidité durant les dépôts, la taille des grains et l'orientation des films Cu2O peuvent être modulées, ainsi des films de Cu2O avec une texturation (111) et une taille de grains > 300 nm ont été obtenus. Pour les films Cu2O optimisés, la mobilité peut atteindre un maximum de 15 cm2 / V.s avec une concentration de porteur de l'ordre de 1015 cm-3. Enfin, un excellent comportement diode a été observé en combinant les films de Cu2O optimisés avec du ZnO, obtenant un rapport on/off supérieur à 104.En raison de l'incompatibilité entre la fenêtre de stabilité thermique associée à AgCuO2 et les températures nécessaires pour déposer des composés Ag et Cu par CVD avec les précurseurs utilisés, le dépôt direct d'AgCuO2 n'a pas pu être obtenu. Ainsi, des techniques de revêtement couche mince à base de solution ont été adoptées pour le dépôt de film AgCuO2. En particulier, la méthode SILAR a permis le dépôt de films minces d’AgCuO2. Grâce à une couche d’amorce sur substrat de verre appropriée, des couches d'AgCuO2 denses et continues ont été revêtues, avec une valeur RMS minimale de 8 nm. Les films d’AgCuO2 déposés avaient une phase presque pure. Les propriétés optiques et de transport des films minces AgCuO2 ont donc été analysées pour la première fois. Les mesures de transmittance ont confirmé la faible largeur de bande interdite prédite d’AgCuO2 (1,2 eV), tandis que grâce à l’utilisation de la formule de Tauc, nous avons constaté que ce matériau est plus susceptible d'avoir une bande interdite directe, en accord avec les calculs DFT publiés. Grâce aux mesures de l'effet Hall, les films AgCuO2 déposés ont été confirmés comme étant de type p. La plus faible résistivité atteinte est de 0,2 Ω.cm. En outre, ces films avaient une densité de porteurs de charge de l'ordre de 1017 cm-3 et la meilleure mobilité atteinte était de 24 cm2 / V.s. En comparaison avec les composés de type p de delafossite précédemment rapportés (M, Al, Cr, Ga, etc.), ce matériau présente la plus petite largeur de bande interdite (intéressant notamment pour l'application photovoltaïque) et une conductivité assez élevée. La caractéristique la plus intéressante est que le problème général de la faible mobilité des transporteurs dans ces composés delafossite a été résolu dans cet AgCuO2, grâce à sa structure électronique mixte et à la délocalisation des charges. Ainsi, ces résultats de caractérisation sans précédent ouvrent la voie à l'utilisation de films AgCuO2 dans des dispositifs fonctionnels. / In recent years, metal oxide electronics has attracted more and more attention in research, mainly thanks to their potential lower cost and the possibility they offer to develop transparent electronics. There are several potential applications concerned with metal oxides including photovoltaics, thin film transistors and photo-electrochemistry. There are several n-type metal oxides with excellent electronic properties being well developed, such as Al doped zinc oxide. But the fabrication of devices fully made with metal oxides is largely impeded by the poor electronic properties of the p-type oxides so far studied. Therefore, there is the need for developing p-type metal oxide semiconducting materials with better electrical properties.In this thesis, the optimization of pure Cu2O thin film deposition was conducted using Aerosol Assisted MOCVD (AA-MOCVD). As a result, homogenous Cu2O films were deposited at low temperature (about 335 °C) without detectable amount of carbon contamination with high crystallinity. In addition, by incorporation of humidity during the deposition, particle size and the orientation of the Cu2O films could be tuned, thus Cu2O films with (111) textured large grain sizes (> 300 nm) were achieved. For optimized Cu2O films, the mobility can reach a maximum of 15 cm2/V.s with carrier concentration in the order of 1015 cm-3. Lastly, an excellent diode behaviour was observed by combining the optimized Cu2O films with ZnO, obtaining an on-off ratio exceeding 104.Besides the Cu2O optimization, the deposition of AgCuO2 by MOCVD was also tackled. In order to do so, the deposition of silver and silver oxide thin films was previously optimized. For that, two new silver precursors, namely, Ag(hfac)phenanthroline and Ag(hfac)triglyme were synthesized and fully characterized. High quality Ag coatings could be obtained with both precursors. Silver oxide films were obtained through electrochemical oxidation and oxygen plasma treatment of pre-deposited Ag coatings.Due to the incompatibility between the thermal AgCuO2 stability window and the temperatures needed to deposit Ag and Cu compounds by CVD with the precursors used, the direct deposition of AgCuO2 could not be obtained. Thus, solution based thin film coating techniques were adopted for AgCuO2 film deposition. In particular, Successive Ionic Layer Adsorption and Reaction (SILAR) allowed the deposition of AgCuO2 thin films. Using a proper seed layer on glass, dense and continuous AgCuO2 films were coated, with minimum RMS value of 8 nm. The deposited AgCuO2 films had almost pure phase. The optical and transport properties of AgCuO2 thin films were thus carried out for the first time. Transmittance measurements confirmed the predicted low bandgap of AgCuO2 (1.2 eV), while by using the Tauc formula, we found that this material is more likely to have a direct bandgap, in agreement with published DFT calculations. Thanks to Hall Effect measurements, the deposited AgCuO2 films were confirmed to be p-type. The lowest resistivity achieved was 0.2 Ω.cm. In addition, those films had carrier density in the order of 1017 cm-3 and the best mobility achieved was 24 cm2/V.s. Comparing with the previously reported CuMO2 (M= Al, Cr, Ga etc) delafossite p-type compounds, this material has shown the lowest bandgap (appropriate for photovoltaic application) and rather high conductivity. The most interesting characteristic is that the general problem of low carrier mobility in those delafossite compounds has been solved in this AgCuO2, thanks to its mixed-valence electronic structure and charges delocalization. Thus, those unprecedented characterization results pave the way for using AgCuO2 films in functional devices.
|
3 |
Estudos das propriedades ópticas e estruturais dos vidros borosilicatos dopados com érbio e prataSouza, Lucelia Celes de 23 July 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-26T14:29:57Z
No. of bitstreams: 1
luceliacelesdesouza.pdf: 2518264 bytes, checksum: 5865f748ffb87158bf1150d3a418b955 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-13T12:02:24Z (GMT) No. of bitstreams: 1
luceliacelesdesouza.pdf: 2518264 bytes, checksum: 5865f748ffb87158bf1150d3a418b955 (MD5) / Made available in DSpace on 2017-05-13T12:02:24Z (GMT). No. of bitstreams: 1
luceliacelesdesouza.pdf: 2518264 bytes, checksum: 5865f748ffb87158bf1150d3a418b955 (MD5)
Previous issue date: 2013-07-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os vidros borosilicato são obtidos a partir da combinação dióxido de silício (SiO2) com o óxido de boro (B2O3). Onde estes vidros possuem um vasto campo de aplicações na indústria vidreira, indo deste os setores de equipamentos de laboratórios até a criação de sensores ópticos (fibras ópticas). Pois, devido à sua forma estrutural estes vidros possuem uma grande resistência a choques térmicos, uma boa durabilidade química e uma excelente resistividade elétrica se comparados com os demais vidros existentes hoje no mercado. Assim baseando-se nestas características importantes características estruturais, físicas, químicas e também na diversidade de aplicações optou-se nesta pesquisa pela síntese e caracterização dos vidros borosilicatos puros e dopados com íons terras raras de érbio e com nitrato de prata. Com o objetivo de conhecer melhor as principais propriedades destas matrizes vítreas desenvolvidas e de como os íons emissores, as nanopartículas metálicas ou ambos se comportam quando estes se encontram inseridos nelas, ou seja, de comprovar que a inserção dos dopantes nas matrizes vítreas de borosilicato modificam tanto as suas propriedades ópticas quanto as estruturais. Assim foram utilizadas as seguintes técnicas de caracterização: análise térmica diferencial, medida de densidade, índice de refração linear, absorção óptica e microscopia eletrônica de transmissão. Visto que à inserção dos íons de érbio em materiais vítreos oferece grandes possibilidades de aplicações tecnológicas nos setores das telecomunicações, com o objetivo de aumentar a capacidade de transmissão de dados. E quanto a inserção das nanopartículas de prata pode se dizer que a mesma produz efeitos ópticos não lineares de terceira ordem nos compósitos e em comprimentos de onda próximos da característica de ressonância de plasmon superficial dos aglomerados de metal. Logo, a partir dos resultados e das análises obtidas foi possível comprovar que as amostras de vidro borosilicato produzidas nesta pesquisa apresentaram resultados satisfatórios e que são similares aos encontrados nas literaturas pertinentes, mostrando que esse é um material promissor para diversas aplicações tecnológicas na área de materiais e óptica. / The borosilicate glasses are obtained from the combination of silicon dioxide (SiO2) with boron oxide (B2O3). Where these glasses have a wide range of applications in the glass industry, the sectors of going this laboratory equipment to the creation of optical (fiber optics). Because, due to its structural form these glasses have a large thermal shock resistance, good chemical durability and excellent electrical resistivity compared with other glasses on the market today. Therefore based on these important structural features, physical, chemical, and also in the variety of applications in this study was chosen for synthesis and characterization of pure borosilicate glass and doped with rare earth ions erbium and silver nitrate. In order to better understand the main properties of these glass matrices developed and how the ion emitters, or both metal nanoparticles behave when they are inserted in them, that , to prove that the insertion of dopants in borosilicate glass matrix changes both their optical and structural properties. We used the following characterization techniques: differential thermal analysis, density measurement, linear refractive index, optical absorption and transmission electron microscopy. Since the insertion of erbium ions in glassy materials has great potential for technological applications in the telecommunications, aiming to increase the capacity of data transmission. And the inclusion of silver nanoparticles nonlinear optical effect of third order in the composites and at wavelengths close to the characteristic surface plasmon resonance of the metal clusters. Thus, from the results and analysis obtained was possible to prove that the samples of borosilicate glass produced in this study showed satisfactory results that are similar to those found in the relevant literature, showing that this is a promising material for technological applications in the area of materials and optics.
|
4 |
Dobijanje i karakterizacija 2D i 3D funkcionalnih materijala iz klase halkogenida dopiranih srebrom / Preparation and characterisation of 2D and 3D functional materials from the group of chalcogenides doped with silverČajko Kristina 13 July 2018 (has links)
<p>Predmet istraživanja ove doktorske disertacije su bila halkogenidna stakla iz sistema Ag<sub>x</sub>(As<sub>40</sub>S<sub>30</sub>Se<sub>30</sub>)<sub>100–x</sub> (x = 0, 0.5, 1, 2, 3, 4, 5, 10, 12, 13, 15 at. % Ag) – 3D forma i tanki filmovi preparirani iz prethodno sintetisanih stakala (x ≤ 5 at. % Ag) – 2D forma.<br />Utvrđena je oblasti amorfnosti u faznom dijagramu po odabranom preseku. Ispitivan je uticaj procentualnog udela srebra na fizičke karakteristike sintetisanih stakala i prepariranih tankih filmova koje su od značaja za primenu ovakvih materijala.<br />Izvršena je karakterizacija električnih, optičkih, strukturnih i termičkih osobina na osnovu kojih su izvedeni zaključci o uticaju i modifikaciji strukture As<sub>40</sub>S<sub>30</sub>Se<sub>30 </sub>halkogenidne matrice usled inkorporacije atoma srebra. Strukturna analiza ispitivanih sastava je potvrdila homogenost uzoraka sa manjom koncentracijom srebra (x ≤ 5 at. % Ag), dok je kod uzoraka sa većim procentualnim udelom ovog metala (x = 10, 13, 15 at. % Ag) pokazano da postoji fazna separacija. Kod sastava sa x = 13 i 15 at. % Ag potvrđena je prisutnost kristalnih centara AgAsSe<sub>2.</sub> Na osnovu rezultata dobijenih DSC tehnikom, pokazano je da pri zagrevanju balk uzoraka dolazi do delimične kristalizacije koja se odvija zapreminski sa dvodimenzionalnim i trodimenzionalnim rastomkristalnih centara. Optička i spektralna ispitivanja su pokazala da uvođenje Ag u matricu stakla As<sub>40</sub>S<sub>30</sub>Se<sub>30</sub> dovodi do smanjenja širine optički zabranjene zone i kod 3D i 2D uzoraka, kao i da svi sastavi ispoljavaju normalan oblik disperzije indeksa prelamanja. Takođe, rezultati Raman spektroskopije su ukazali na činjenicu da inkorporacija srebra u strukturnu mrežu ispitivanih stakala utiče na formiranje Ag–(S,Se)–As veza, odnosno uzrokuje formiranje novih strukturnih jedinica koje bi mogle uticati na provodljivost ovih sastava. Merenja električnih karakteristika 3D uzoraka izvršena su u jednosmernom i naizmeničnom režimu i pokazano je da koncentracija srebra ima značajan uticaj na električne osobine. Utvrđeni su različiti mehanizmi odgovorni za transport nosilaca naelektrisanja zavisno od koncentracije dopanta. Kompleksni impedansni spektri svih sastava su ukazali na prisustvo temperaturske zavisnosti procesa relaksacije, na ne idealan Debye–vski tip relaksacije, kao i negativni temperaturski koeficijent otpornosti koji je karakterističan za poluprovodnike.</p> / <p>The subject of this dissertation are chalcogenide glasses from the system Agx(As<sub>40</sub>S<sub>30</sub>Se<sub>30</sub>)<sub>100–x</sub> (x = 0, 0.5, 1, 2, 3, 4, 5, 10, 12, 13, 15 at. % Ag) – 3D form and thin films prepared from previously synthesised glasses (x ≤ 5 at. % Ag) – 2D form. The amorphous area in the phase diagram was determined by the selected tie– line. The influence of the silver percentage on the physical characteristics of the synthesized glasses and prepared thin films was investigated due to the importance of such materials for the application. Characterization of electrical, optical, structural and thermal properties has been performed, based on which conclusions on theinfluence and structure modification of the As<sub>40</sub>S<sub>30</sub>Se<sub>30</sub> chalcogenide matrix due to the incorporation of silver atoms have been derived. Structural analysis of the investigated samples confirmed the homogeneity of samples with a lower silver concentration (x ≤ 5 at.% Ag), while in samples with a higher percentage content of this metal (x = 10, 13, 15 at.% Ag) it was shown that there was a phase separation. The presence of crystal centers AgAsSe<sub>2</sub> was confirmed in the samples with x = 13 and 15 at. % Ag. Based on the results obtained with the DSC technique, it has been shown that by heating the samples, partial crystallization takes place voluminously, with two–dimensional and three–dimensional growth of crystalline centers. Opticaland spectral investigations have shown that the introduction of Ag into the glass matrix As<sub>40</sub>S<sub>30</sub>Se<sub>30</sub> leads to a reduction in the optical band gap in both 3D and 2D samples, and that all compositions exhibit a normal dispersion of index of refraction. Also, the Raman spectroscopy results pointed to the fact that the incorporation of silver into the structural network of the investigated samples influences the formation of Ag–(S,Se)–As structures that is, causes the formation of new structural units that could affect the conductivity of these compositions. Measurements of the electrical characteristics of the 3D samples were performed in DC and AC regime and it was shown that silver concentration has a significant effect on electrical properties. Different mechanisms that are responsible for the transport of charge carriers depending on dopant concentration were determined. The complex impedance spectra of all compositions indicated the presence of the temperature dependence of the relaxation process, the non–Debye relaxation and the negative temperature coefficient of resistance which is characteristic of the semiconductors.</p>
|
5 |
Äggskal,avfall eller resurs? : En materialdriven designprocessSofee, Sofidar January 2021 (has links)
Egg consumption in Sweden is very high, which means a lot of egg shells are thrown out. For example the average swede consumes about 350 eggs every year. In this thesis I have investigated how eggshells can be applied in new areas as a resource, and I want to inspire the reader and encourage them to rethink what is called waste. Is it really waste or a possible resource? The work began with literature search, interviews and a survey to understand people's views on eggshells. I have concluded that not a lot of people know what eggshells are made of, and what they are used for. In a literature search I came across many scientific articles on eggshells. According to King’ori (2011) eggshells are used as fertilizers, used in medicine, cosmetic surgery, and dental care, calcium supplements, in the food industry and in crafts. When eggshell is thrown as food waste it creates problems in recycling stations, the eggshell is like sediment and lies at the bottom of tanks and pipes. The recycling staff have to perform additional work when cleaning tanks and pipes as eggshells are like sediment and lay at the bottom. The staff have to manually shoot out eggshells with many other useful materials that could have been digested and become biogas. This is an exploratory thesis where I investigate the material eggshell through a material-driven design process to find new sustainable uses. I follow the material-driven design process method by Karana et al.( 2015) plus my own added steps during the process. Material driven design process is a process where designers use a material to find the attributes of the material. These are then presented in new contexts or already existing contexts, this means that the material on the existing product can be replaced. This differs from traditional design, where the material is chosen based on wanted attributes. This report will give you an understanding of the material-driven design process-method and how I have carried out a material-driven design process, to develop different material properties of eggshells. The report ends with a concluding discussion and presents new eggshell-based materials that I have produced in the form of a demonstrator. It is a book which has two different materials, a hard material and a paper material which are combined and put together with a steel thread. I will also share my knowledge about eggshells and what potential it has in the future.
|
6 |
Biom / BiomBolcek, Roman Unknown Date (has links)
Our planet has been facing enormous challenges over the last century, caused by population growth, an ever-evolving industry, resulting in ever-increasing CO2 production, rising water levels, misuse of agricultural land and the extinction of animal species. This causes the destruction of the Biome. Architectural and urban tendencies in the construction of cities, which do not change even today, use the maximum area, materials that cannot be recycled, also have a large share in this. Insufficient use of renewable resources, modern agriculture, self-sufficiency, both housing and urban structures. The reason for not using these technologies is largely a political and commercial problem. The aim of this work is to examine the problems we face today and find meaningful solutions. Change existing architectural and urban trends. To create a self-sufficient structure in places where Biomes were destroyed and to create new ones accordingly. These places often have poor living conditions, such as high temperatures, lack of drinking water and overcrowding. With the help of simple rules of working with the landscape and the use of modern technology, create a new biosphere environment, change the climatic conditions in a given place and create suitable conditions for the life of both plant and animal communities. The structure should be inhabited by a certain number of people who will live in modules that will be fully self-sufficient, following the ISS model. Provide plenty of drinking water, food and energy. The structure should be created from plastic waste by new construction technologies, such as 3D printing using nanotechnology and carbon fiber. This should make it fully recyclable and renewable. The goal is to work with one structure and subsequently create another structure.
|
7 |
Anisotropia de resistividade elétrica em filmes finos nanoestruturados. / Electrical resistivity anisotropy in nanostructured thin films.Teixeira, Fernanda de Sá 18 May 2007 (has links)
O objetivo principal deste trabalho foi desenvolver um dispositivo de filme fino com anisotropia de resistividade elétrica. A idéia foi usar um efeito quântico presente em filmes muito finos de materiais condutores ou semicondutores com morfologia anisotrópica na superfície. A morfologia foi um perfil unidirecional quase-senoidal. As resistividades foram determinadas medindo-se as resistências elétricas destes materiais em direções ortogonais, levando-se em conta a geometria da amostra e suas dimensões. O material condutor usado foi Polimetilmetacrilato (PMMA) com ouro implantado na superfície. A profundidade média de implantação foi 2,7 nm. Na fabricação do dispositivo foi utilizada micro e nanolitografia, caracterização por Microscopia Eletrônica de Varredura e Microscopia de Força Atômica e implantação de ouro por MePIIID (Metal Plasma Immersion Ion Implantation and Deposition). / The main purpose of this work was to develop a thin film device with electrical anisotropic resistivity. The idea was to use a quantum effect which is present in very thin films of conductor or semiconductor materials with anisotropic morphology on the surface. The morphology was a sinusoidal-like unidirectional profile. The resistivities were determined measuring the electrical resistances of theses materials in orthogonal directions, taking in account the sample geometry and dimensions. The conductive material used was Polymethylmethacrylate (PMMA) with gold implanted on the surface. The average implanted depth was 2.7 nm. In the device fabrication were used micro and nanolithography, characterization by Scanning Electron Microscopy and Atomic Force Microscopy and gold implantation by MePIIID (Metal Plasma Immersion Ion Implantation and Deposition).
|
8 |
Trend-sandwich : Exploring new ways of joining inspiration, such as different kinds of trends, through processes of morphing and melding different trendy garments and materials, for new methods, garment types, materials and expressions.Bendzovski, Daniel January 2015 (has links)
The aim of this work is to explore the joining of inspiration, such as different garments and materials, in relation to commonly used methods in the fashion industry when it comes to joining of different trends and references such as clashing and collaging. The work proposes a new method and framework for join- ing inspiration which generates different results depending on what kind of inspiration that is put in to it. A garment can roughly be broken down to a silhouette and shape, materials and details. The material put in to the method and framework is based on information from trend seminars for SS16, because that is how many of today’s trend-oriented fashion brands get there inspiration. Trendy garment silhouettes are mixed through processes of computational morphing in Adobe Flash by a generation of spin in the mixing process were shape hints are used in a new manner. The new generated silhouettes are further developed and materialized through procedures of interpretation and figuration. Different trendy materials are melded in a direct and concrete way through mixed media techniques such as laminating, fusing and vacuum-techniques. The final steps of the method is a garment shape and material synthesis with starting point in the generated shape with the final material. The projects intention is to let the physical experimentation, interpretation and figuration play a central role in the research process for new types of methods, garments, materials and expressive pos- sibilities.
|
9 |
Μελέτη, χαρακτηρισμός και ιδιότητες νέων υλικών υψηλής τεχνολογίας / Growth, characterization and properties of new high tech materialsΓραμματικόπουλος, Σπυρίδων 11 March 2014 (has links)
Το αντικείμενο της παρούσας Διδακτορικής Διατριβής είναι η ανάπτυξη νέων υλικών για σύγχρονες τεχνολογικές εφαρμογές. Για αυτό τον λόγο, επιλέχτηκε κατ’ αρχήν να αναπτυχθεί μια καινούρια και ταυτόχρονα πρωτότυπη διαδικασία παρασκευής νανοσωματιδίων. Για το σκοπό αυτό σχεδιάστηκε και ανακατασκευάστηκε εξ’ αρχής μια υπάρχουσα συσκευή sputtering, εφαρμόζοντας νέες τεχνικές και διατάξεις για την εναπόθεση των λεπτών και υπέρλεπτων υμενίων χρυσού σε διαφορετικές θερμοκρασίες υποστρώματος.
Παρασκευάστηκαν δείγματα σε κρυογενικές θερμοκρασίες εναπόθεσης (-195 oC) έως και σε υψηλές Θερμοκρασίες των 450 oC. Παράλληλα πραγματοποιήθηκε και σύγκριση με μια σειρά δειγμάτων λεπτών υμενίου χρυσού με θερμική ανόπτηση μετά την εναπόθεση έως τους 800 oC. Αφού μελετήθηκε ο τρόπος ανάπτυξης των υμενίων του χρυσού με αυτές τις τεχνικές, και χαρακτηρίστηκαν τα λεπτά υμένια με διαφόρους τρόπους, επιλέχθηκε η πιο αποδοτική από μορφολογικής άποψης μέθοδος, για την παρασκευή νανοσωματιδίων χρυσού. Έτσι παρασκευάστηκαν υπέρλεπτα υμένια χρυσού, κάτω από συγκεκριμένες συνθήκες. Αυτά τα δείγματα έδωσαν νανοσωματίδια χρυσού της τάξεως των μερικών νανομέτρων, ικανά να δώσουν βάση των φασμάτων απορρόφησης, επιφανειακούς πλασμονικούς συντονισμούς σε διάφορα μήκη κύματος από τα 2 - 2,5 eV ανάλογα με το μέγεθος των νανοσωματιδίων που καθορίζουμε από τις συνθήκες του πειράματος.
Στην συνέχεια παρασκευάστηκαν αντίστοιχα δείγματα από ένα νέο σύγχρονο υλικό, που αποτελείται από χρυσό, γερμάνιο και άργυρο. Χρησιμοποιώντας την ίδια διάταξη παρασκευάστηκαν αντίστοιχα υπέρλεπτα υμένια, στα οποία ανιχνεύτηκαν υβριδικά νανοσωματίδια χρυσού – αργύρου σε αναλογίες 1:1, προστατευμένα από μια άμορφη υαλώδη μήτρα οξειδίου του γερμανίου. Τέλος, κατά τον οπτικό χαρακτηρισμό των δειγμάτων αυτών και διαπιστώθηκε από τα φάσματα απορρόφησης συνδυασμένος επιφανειακός πλασμονικός συντονισμός.
Τέλος, τα μεταλλικά και τα ημιαγώγιμα υπέρλεπτα υμένια έχουν τεράστια σημασία σε διάφορους τομείς της επιστήμης των υλικών και της νανοτεχνολογίας. Έτσι, η πρωτότυπη πειραματική διάταξη που αναπτύχτηκε είναι ενδιαφέρουσα για την παρασκευή μιας πληθώρας νάνο-ηλεκτρομηχανικών και οπτοηλεκτρονικών συστημάτων βασισμένα σε διάφορα σύγχρονα υλικά. / The objective of this Thesis is to develop new high – Tech materials for modern technological applications. For this reason, we have chosen in principle to develop a new prototype manufacturing process for growth of nanoparticles. For this purpose we designed and rebuilt from the beginning an existing D.C. sputtering apparatus to apply new techniques and devices for the deposition of thin and ultrathin films of gold at various substrate temperatures.
We prepared samples at cryogenic temperatures deposition (-195 oC) up to a high temperature of 450 oC. The results were compared with a series of samples of thin gold films post annealed up to 800 oC. After studying the growth modes of thin gold films with these techniques, and characterize thin films in different ways, we chose the most efficient method from morphological point of view, for the optimum preparation of gold nanoparticles.
So we proceeded to the deposition of ultrathin gold films, under certain conditions. These samples gave us gold nanoparticles in the range of a few nanometers, able to give us surface plasmon resonances at different wavelengths from 2 - 2,5 eV depending on the size of nanoparticles.
Then samples were prepared respectively from a modern new target material consisting of gold, germanium and silver. Using the same configuration we were able to prepare ultrathin films. These films were found to consist of Au-Ag nanoparticles self-organized in an amorphous GeOx matrix. Finally, we proceeded to the optical characterization of these samples and found on the absorption spectra combined surface plasmon resonances.
Finally, the metal and the semiconductor ultrathin films are crucial in various fields of materials science and nanotechnology. Thus, the original experimental setup which was developed is useful in order to prepare a multitude of nano - electromechanical and optoelectronic systems based on various modern materials.
|
10 |
Anisotropia de resistividade elétrica em filmes finos nanoestruturados. / Electrical resistivity anisotropy in nanostructured thin films.Fernanda de Sá Teixeira 18 May 2007 (has links)
O objetivo principal deste trabalho foi desenvolver um dispositivo de filme fino com anisotropia de resistividade elétrica. A idéia foi usar um efeito quântico presente em filmes muito finos de materiais condutores ou semicondutores com morfologia anisotrópica na superfície. A morfologia foi um perfil unidirecional quase-senoidal. As resistividades foram determinadas medindo-se as resistências elétricas destes materiais em direções ortogonais, levando-se em conta a geometria da amostra e suas dimensões. O material condutor usado foi Polimetilmetacrilato (PMMA) com ouro implantado na superfície. A profundidade média de implantação foi 2,7 nm. Na fabricação do dispositivo foi utilizada micro e nanolitografia, caracterização por Microscopia Eletrônica de Varredura e Microscopia de Força Atômica e implantação de ouro por MePIIID (Metal Plasma Immersion Ion Implantation and Deposition). / The main purpose of this work was to develop a thin film device with electrical anisotropic resistivity. The idea was to use a quantum effect which is present in very thin films of conductor or semiconductor materials with anisotropic morphology on the surface. The morphology was a sinusoidal-like unidirectional profile. The resistivities were determined measuring the electrical resistances of theses materials in orthogonal directions, taking in account the sample geometry and dimensions. The conductive material used was Polymethylmethacrylate (PMMA) with gold implanted on the surface. The average implanted depth was 2.7 nm. In the device fabrication were used micro and nanolithography, characterization by Scanning Electron Microscopy and Atomic Force Microscopy and gold implantation by MePIIID (Metal Plasma Immersion Ion Implantation and Deposition).
|
Page generated in 0.0929 seconds