Dissertations / Theses on the topic 'STM lithography'
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Ruess, Frank Joachim Physics Faculty of Science UNSW. "Atomically controlled device fabrication using STM." Awarded by:University of New South Wales. Physics, 2006. http://handle.unsw.edu.au/1959.4/24855.
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We present the development of a novel, UHV-compatible device fabrication strategy for the realisation of nano- and atomic-scale devices in silicon by harnessing the atomic-resolution capability of a scanning tunnelling microscope (STM). We develop etched registration markers in the silicon substrate in combination with a custom-designed STM/ molecular beam epitaxy system (MBE) to solve one of the key problems in STM device fabrication ??? connecting devices, fabricated in UHV, to the outside world. Using hydrogen-based STM lithography in combination with phosphine, as a dopant source, and silicon MBE, we then go on to fabricate several planar Si:P devices on one chip, including control devices that demonstrate the efficiency of each stage of the fabrication process. We demonstrate that we can perform four terminal magnetoconductance measurements at cryogenic temperatures after ex-situ alignment of metal contacts to the buried device. Using this process, we demonstrate the lateral confinement of P dopants in a delta-doped plane to a line of width 90nm; and observe the cross-over from 2D to 1D magnetotransport. These measurements enable us to extract the wire width which is in excellent agreement with STM images of the patterned wire. We then create STM-patterned Si:P wires with widths from 90nm to 8nm that show ohmic conduction and low resistivities of 1 to 20 micro Ohm-cm respectively ??? some of the highest conductivity wires reported in silicon. We study the dominant scattering mechanisms in the wires and find that temperature-dependent magnetoconductance can be described by a combination of both 1D weak localisation and 1D electron-electron interaction theories with a potential crossover to strong localisation at lower temperatures. We present results from STM-patterned tunnel junctions with gap sizes of 50nm and 17nm exhibiting clean, non-linear characteristics. We also present preliminary conductance results from a 70nm long and 90nm wide dot between source-drain leads which show evidence of Coulomb blockade behaviour. The thesis demonstrates the viability of using STM lithography to make devices in silicon down to atomic-scale dimensions. In particular, we show the enormous potential of this technology to directly correlate images of the doped regions with ex-situ electrical device characteristics.
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Lakcher, Amine. "Nouvelles perspectives de métrologie dimensionnelle par imagerie de microscope électronique pour le contrôle de la variabilité des procédés de fabrication des circuits intégrés." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT052/document.
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Dans les noeuds technologiques avancés ainsi que les technologies dérivées, des règles de dessin de plus en plus aggressives sont nécessaires. Cela conduit à une complexification des structures dans les circuits intégrés actuels. De telles structures posent un défi important aux procédés de fabrication, notamment les étapes dites de patterning que sont la lithographie et la gravure. Afin d'améliorer et d'optimiser ces structures, les designers se basent sur les règles et connaissances qu’ont les ingénieurs de leurs procédés. Ces règles ont besoin d'être alimentées par des informations dimensionnelles et structurelles de plus en plus complexes : configurations de type bord arrondi, distance entre deux bouts de lignes, rétrecissement de ligne, etc. La métrologie doit évoluer afin que les ingénieurs soient capables de mesurer et quantifier les dimensions des structures les plus complexes dans le but d'estimer la variabilité de leur procédé. Actuellement la variabilité est principalement estimée à partir de données issues du suivi en ligne de structures simples car elles sont les seules à garantir une mesure robuste et reproductible. Mais, elles peuvent difficilement être considérées comme représentatives du procédé ou du circuit. Utiliser la métrologie par CD-SEM pour mesurer des structures complexes de manière robuste est un défi technique. La création de recettes de mesures est complexe, nécessite un temps non négligeable et ne garantit pas une mesure stable. Cependant, une quantité importante d'informations est contenue dans l'image SEM. Les outils d'analyses fournis par les équipementiers permettent aujourd'hui d'extraire les contours SEM d'une structure présente dans l’image. Ainsi, le CD-SEM prend des images et la partie métrologie est réalisée hors ligne afin d'estimer la variabilité. Cette thèse vise à proposer aux ingénieurs de nouvelles possibilités de métrologie dimensionnelle afin de l’appliquer pour le contrôle des structures les plus complexes. Les contours SEM sont utilisés comme source d’information et exploités pour générer de nouvelles métriquesIn advanced technological nodes as well as derived technologies, aggressive design rules are needed. This leads to a complexity of structures in the current integrated circuits. Such structures pose a significant challenge to chip manufacturing processes, in particular patterning steps of lithography and etching. In order to improve and optimize these structures, designers need to rely on the rules and knowledge that engineers have about their processes. These rules need to be fed by complex dimensional and structural information: corner rounding, tip to tip distances, line end shortening, etc. Metrology must evolve so that engineers are able to measure and quantify the dimensions of the most complex structures in order to assess the process variability. Currently the variability is mainly quantified using data from the inline monitoring of simple structures as they are the only ones to guarantee a robust and reproducible measurement. But, they can hardly be considered as representative of the process or the circuit. Using CD-SEM metrology to measure complex structures in a robust way is a technical challenge. The creation of measurement recipes is complex, time consuming and does not guarantee a stable measurement. However, a significant amount of information is contained in the SEM image. The analysis tools provided by the equipment manufacturers allow to extract the SEM contours of a structure present in the image. Thus, the CD-SEM takes images and the metrology part is performed offline to estimate the variability.This thesis offers engineers new possibilities of dimensional metrology in order to apply it for process control of complex structures. SEM contours are used as a source of information and used to generate new metrics
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Konijn, Mark. "Multilevel Nanoengineering for Imprint Lithography." Thesis, University of Canterbury. Electrical and Computer Engineering, 2005. http://hdl.handle.net/10092/1071.
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The current trend in pushing photo lithography to smaller and smaller resolutions is becoming increasingly difficult and expensive. Extreme ultra-violet lithography is an alternate method that has the potential to provide feature sizes down to 30 nm, however, it will come at an even greater cost. Nanoimprint lithography (NIL) is another lithographic technique which is promising to provide very high resolutions at a relatively low cost. Imprinting works by using a mold with a surface patterned with the required nano structures and pressing it into a substrate coated with a deformable polymer. Due to its direct pattern replication technique, it is very capable of reproducing three-dimensional structures, however limited research has been performed on this to date. In this study, investigations have been performed into developing a reliable process for creating SiN molds with sub-100 nm structures with variable height control. The process relies on a negative tone electron beam resist which can be patterned to various thicknesses by varying the exposure dosage. This allows for the creation of complex multi-layer structures in a single electron beam lithography step. These patterns then have been transferred into the SiN substrate by a single reactive ion etch. From here the mold is ready for use in imprinting. Study has also been performed into imprinting process as well. This includes the development of an imprint press, the manner in which NIL works. Investigations have been performed into the imprinting performance of 3D molds. Thermal expansion issues have been found and addressed, as have adhesion problems. Some other aspects of 3D NIL which have not been addressed in this study have been outlined in future work for further investigation.
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Perring, Mathew Ian. "Functionalization and patterning of monolayers on silicon(111) and polydicyclopentadiene." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/722.
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The formation of a functional surfaces combines the properties of a substrate and monolayer to produce a new hybrid that can combine aspects of each. Monolayers can be made on many surfaces, and well defined functionalized monolayers were assembled on for silicon(111) and polydicyclopentadiene (PDCPD).
Acid terminated monolayers were assembled on silicon(111) and their functionalization chemistry explored. It was shown that using trifluoroacetic anhydride to generate an intermediate reactive anhydride, the surface could be functionalized with amines. It was further shown that using soft lithography these functionalized surfaces could be patterned.
Mixed monolayers of methyl and olefin terminated surfaces on silicon(111) were used to develop a new soft lithographic technique with polydimethylsiloxane (PDMS). PDMS can be controllably etched using fluoride species. The surface is first activated by the attachment of the Grubbs' 1st generation catalyst. A PDMS microfluidic device is then placed on the surface. By using a cross metathesis reaction, the exposed channel can be pacified. The next step, a fluoride etchant is used to remove PDMS, exposing an unreacted surface. Polymer brushes were then grown by ring opening metathesis polymerization (ROMP) in this region.
Functionalization of the emerging polymer PDCPD was conducted through two different routes. ROMP formed PDCPD has double bonds that can be functionalized. In the first process, the double bonds were reacted with bromine. This is a rapid reaction and proceeds to a significant depth in the material. Bromines can then be displaced with amines in a substitution reaction. This was demonstrated with a fluorinated amine that when examined by XPS were shown to be present only at the surface, further more we were able to pattern this surface too. Secondly, a process using epoxides was developed. The epoxidation reaction could not be quantified, but formation in the second step of an amine functionalized surfaces was observed by XPS. Further reaction of surface hydroxyls was also observed. This was also used to grow polyethylimine from the surface to sufficient thickness that it became observable by infrared spectroscopy.
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Costa, Juliano Nunes. "Projeto, fabricação e teste de uma microbomba sem valvulas." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264091.
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Orientador: Euripedes Guilherme de Oliveira NobregaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Hoje em dia, os microssistemas eletromecânicos (MEMS) constituem uma das áreas mais promissoras e de rápido crescimento entre as novas tecnologias. Uma área de destaque na utilização de MEMS é a microfluídica, onde diversos tipos de equipamentos miniaturizados são necessários. As microbombas têm um papel fundamental neste tipo de microdispositivos, devido a sua função de prover quantidades muito pequenas de fluidos de maneira segura e uniforme. O presente trabalho apresenta o processo de desenvolvimento de uma microbomba de diafragma oscilante sem válvulas e com atuação pneumática. Para se construir a microbomba sem válvulas, primeiramente foi feito um estudo sobre os elementos bocaljdifusor, que representam na microbomba o papel das válvulas. Com o objetivo de se analisar o comportamento da microbomba, foi feita uma simulação numérica utilizando-se a analogia por circuitos elétricos equivalentes, reconhecidamente um método simples e eficiente' de simulação de sistemas multidomínios, onde a grande maioria dos microdispositivos podem ser classificados. Por fim, foram projetados e montados protótipos da microbomba utilizahdo-se a tecnologia de microfabricação Litografia Profunda em polímeros flexográficos, onde se faz o uso de radiação ultravioleta. Tal opção se deve a que esta é uma tecnologia de baixo custo e de fácil utilização. Foi feito em seguida o levantamento de desempenho da microbomba, onde vários testes foram realizados para se conhecer a relação de pressão versus vazão
Abstract: Nowadays, Micro-Electromechanical systems (MEMS) constitute one of the most promising and fast expanding fields among the new technologies. Microfiuidic systems are a noteworthy sub-area of MEMS, demanding several types of microdevices to be developed. Micropumps have a fundamental role in thee systems, due to the need of supplying minimal amounts of fiuid in a guaranteed and uniform way. This work presents the process of development of. prototypes of aval veless micropump based upon reciprocating diaphragm and pneumatic actuation. To construct the valveless micropump, firstly it was made a study on the nozzlej diffuser elements, which represent in these micropumps the valve function. Aiming to analyse the behavior of the micropump, a numeric simulation was studied using electrical equivalent networks, known as a simple and eflicient method of simulation of multidomain systems, a classification most MEMS follow. Finally, it was designed and constructed prototypes of the micropumps using the Deep Lithography in fiexographics polymers micro-manufacture technology. This option is due to the low cost characteristic of this technology and also because it is very easy to learn how to produce the prototypes. ln the sequence, the nerformance of the micropump was studied through several experimental tests in order to know its pressure and fiow behavior
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Kim, Eun Jung. "Surface Microtopography Modulation of Biomaterials for Bone Tissue Engineering Applications." Cleveland State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1273557062.
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Cheng, Zhe Annie. "Biological multi-functionalization and surface nanopatterning of biomaterials." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR15202/document.
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Le but de la conception d’un biomatériau est de mimer les modèles qui puissent être représentatifs de la matrice extracellulaire (MEC) existant in vivo. Cet objectif peut être atteint en associant une combinaison de cellules et des facteurs biologiques à un biomatériau sur lequel ces cellules peuvent se développer pour reconstruire le tissu natif. Dans cet étude, nous avons crée des surfaces bioactives nanostructurées en combinant la nanolithographie et la fonctionnalisation de surface, en greffant un peptide RGD ou BMP-2 (bone morphogenetic protein 2). Nous avons étudié l’effet de cette nanodistribution sur le comportement des cellules souches mésenchymateuses en analysant leur adhésion et différentiation. Nous notons que la nanodistribution des peptides induit une bioactivité qui a un impact sur l’organisation du cytosquelette, la conformation des fibres de stresse de l’actin, la maturation des adhésions focales (AFs), et le commitment des cellules souches. En particulier, l’aire, la distribution, et la conformation des AFs sont affectes par la présence des nanopatterns. En plus, le RGD et le BMP-2 changent le comportement cellulaire par des voies et des mécanismes différents en variant l’organisation des cellules souches et la maturation de leurs AFs. La nanodistribution influence de façon évidente les cellules souches en modifiant leur comportement (adhésion et différenciation) ce qui a contribué et ce qui contribuera à améliorer la compréhension des interactions des cellules avec la MECThe aim of biomaterials design is to create an artificial environment that mimics the in vivo extracellular matrix for optimized cell interactions. A precise synergy between the scaffolding material, bioactivity, and cell type must be maintained in an effective biomaterial. In this work, we present a technique of nanofabrication that creates chemically nanopatterned bioactive silicon surfaces for cell studies. Using nanoimprint lithography, RGD and mimetic BMP-2 peptides were covalently grafted onto silicon as nanodots of various dimensions, resulting in a nanodistribution of bioactivity. To study the effects of spatially distributed bioactivity on cell behavior, mesenchymal stem cells (MSCs) were cultured on these chemically modified surfaces, and their adhesion and differentiation were studied. MSCs are used in regenerative medicine due to their multipotent properties, and well-controlled biomaterial surface chemistries can be used to influence their fate. We observe that peptide nanodots induce differences in MSC behavior in terms of cytoskeletal organization, actin stress fiber arrangement, focal adhesion (FA) maturation, and MSC commitment in comparison with homogeneous control surfaces. In particular, FA area, distribution, and conformation were highly affected by the presence of peptide nanopatterns. Additionally, RGD and mimetic BMP-2 peptides influenced cellular behavior through different mechanisms that resulted in changes in cell spreading and FA maturation. These findings have remarkable implications that contribute to the understanding of cell-extracellular matrix interactions for clinical biomaterials applications
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Scott, Kevin. "Fabrication and Characterization of Magnetic Nanostructures." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5437.
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Magnetic permalloy nanostructures were fabricated onto a silicon wafer using electron beam lithography and a liftoff process. The lithography was performed with a Hitachi SU-70 SEM retrofitted with a Nabity NPGS lithography conversion kit. PMMA of 950kDa molecular weight was used as the photoresist. Features were either nanowires, nanodots, or elliptical or rectangular nanostructures. The nanowires had dimensions of 15µm x 200nm x 40nm, the nanodots had diameters of 145nm and thickness of 12nm, and the ellipses and rectangles had dimensions of 110nm x 50nm x 13nm. Characterization of the nanostructures was performed using the same Hitachi SEM as well as a Digital Instruments DI 3100 Nanoscope IIIa AFM used in magnetic force imaging mode. The SEM was used to measure lateral dimensions of the features and to capture images of features for proper documentation and for external simulation studies. The MFM was used to capture magnetic images of the samples to determine the magnetic state of the nanowires or arrays.
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Blom, Tobias. "Fabrication and Applications of a Focused Ion Beam Based Nanocontact Platform for Electrical Characterization of Molecules and Particles." Doctoral thesis, Uppsala universitet, Experimentell fysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122940.
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The development of new materials with novel properties plays an important role in improving our lives and welfare. Research in Nanotechnology can provide e.g. cheaper and smarter materials in applications such as energy storage and sensors. In order for this development to proceed, we need to be able to characterize the material properties at the nano-, and even the atomic scale. The ultimate goal is to be able to tailor them according to our needs. One of the great challenges concerning the characterization of nano-sized objects is how to achieve the physical contact to them. This thesis is focused on the contacting of nanoobjects with the aim of electrically characterizing them and subsequently understanding their electrical properties. The analyzed nanoobjects are carbon nanosheets, nanotetrapods, nanoparticles and molecular systems. Two contacting strategies were employed in this thesis. The first strategy involved the development of a focused ion beam (FIB) based nanocontact platform. The platform consists of gold nanoelectrodes, having nanogaps of 10-30 nm, on top of an insulating substrate. Gold nanoparticles, double-stranded DNA and cadmium telluride nanotetrapods have been trapped in the gaps by using dielectrophoresis. In certain studies, the gold electrodes have also been coated with conducting or non-conducting molecules, prior to the trapping of gold nanoparticles, in order to form molecular junctions. These junctions were subsequently electrically characterized to evaluate the conduction properties of these molecular systems. For the purpose of better controlling the attachment of molecules to the nanoelectrodes, a novel route to synthesize alkanedithiol coated gold nanoparticles was developed. The second contacting strategy was based on the versatility of the FIB instrument as a platform for in-situ manipulation and electrical characterization of non-functionalized and functionalized carbon nanosheets, where it was found that the functionalized samples had an increased conductivity by more than one order of magnitude. Both contacting strategies proved to be valuable for building knowledge around contacting and electrical characterization of nanoobjects
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Cheng, Zhe. "Biological multi-functionalization and surface nanopatterning of biomaterials." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-01016695.
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The aim of biomaterials design is to create an artificial environment that mimics the in vivo extracellular matrix for optimized cell interactions. A precise synergy between the scaffolding material, bioactivity, and cell type must be maintained in an effective biomaterial. In this work, we present a technique of nanofabrication that creates chemically nanopatterned bioactive silicon surfaces for cell studies. Using nanoimprint lithography, RGD and mimetic BMP-2 peptides were covalently grafted onto silicon as nanodots of various dimensions, resulting in a nanodistribution of bioactivity. To study the effects of spatially distributed bioactivity on cell behavior, mesenchymal stem cells (MSCs) were cultured on these chemically modified surfaces, and their adhesion and differentiation were studied. MSCs are used in regenerative medicine due to their multipotent properties, and well-controlled biomaterial surface chemistries can be used to influence their fate. We observe that peptide nanodots induce differences in MSC behavior in terms of cytoskeletal organization, actin stress fiber arrangement, focal adhesion (FA) maturation, and MSC commitment in comparison with homogeneous control surfaces. In particular, FA area, distribution, and conformation were highly affected by the presence of peptide nanopatterns. Additionally, RGD and mimetic BMP-2 peptides influenced cellular behavior through different mechanisms that resulted in changes in cell spreading and FA maturation. These findings have remarkable implications that contribute to the understanding of cell-extracellular matrix interactions for clinical biomaterials applications.
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Hrabovský, Miloš. "Příprava a použití exfoliovaných grafitových/grafenových vrstev v oblasti nanosenzoriky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231377.
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Tato diplomová práce se věnuje výrobě vrstev grafitu/grafenu a meření jejich transportních vlastností v závislosti na relativní vlhkosti. Grafenové šupinky byly nanášeny pomocí mechanického odlupování . Pro kontaktování grafenových šupinek byla využita elektronová litografie a na pozorování byly využity optická mikroskopie, mikroskopie atomárních sil a elektronová mikroskopie. V práci jsou popsány jednotlivé kroky výroby, analýzy a měření transportních vlastností nanesených grafenových šupinek.
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Rundqvist, Jonas. "Nanometer Scale Protein Templates for Bionanotechnology Applications." Doctoral thesis, KTH, Physics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-530.
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Nanofabrication techniques were used to manufacture nanometer scale protein templates. The fabrication approach employs electron beam lithography (EBL) patterning on poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)17NHCO(CH2)2SH) self-assembled monolayers (SAM) on Au. The PEG SAM prevented protein surface adhesion and binding sites for protein were created in the SAM by EBL. Subsequent to EBL, the patterns in the PEG SAM were backfilled with 40-nm NeutrAvidin-coated fluorescent spheres (FluoSpheres). The spontaneous and directed immobilization of the spheres from a solution to the patterns resulted in high resolution protein patterns. The FluoSpheres could be arranged in any arbitrary pattern with ultimately only one or a few FluoSpheres at each binding site.
Growth dynamics and SAM morphology of PEG on Au were studied by atomic force microscopy (AFM). PEG SAMs on three types of Au with different microstructure were examined: thermally evaporated granular Au and two types of Au films produced by hydrogen flame annealing of granular Au, Au(111) and "terraced" Au (crystal orientation unknown). The different Au surfaces' substructure affected the morphology and mechanical properties of the PEG SAM. On Au(111), AFM imaging revealed monolayer formation through three distinct steps: island nucleation, island growth, and coalescence. The fine-structure of the SAM revealed dendritic island formation - an observation which can be explained by attractive intermolecular interactions and diffusion-limited aggregation. Island growth was not observed on the "terraced" Au.
AFM studies of EBL patterned PEG SAMs on Au(111) revealed two different patterning mechanisms. At low doses, the pattern formation occurs by SAM ablation in a self-developing process where the feature depth is directly dose dependent. At higher doses electron beam induced deposition of material, so-called contamination writing, is seen in the ablated areas of the SAM. The balance between these two mechanisms is shown to depend on the geometry of the pattern.
In addition to PEG SAMs, fibronectin monolayers on SiO2 surfaces were patterned by EBL. The areas exposed with EBL lose their functionality and do not bind anti-fibronectin. With this approach we constructed fibronectin templates and used them for cell studies demonstrating pattern dependent cell geometries and cell adhesion.
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Botton, Julien. "Nanolithographie par sonde locale catalytique : une approche bottom-up pour la nanostructuration de surfaces organominérales." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4389.
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Face à la quête constante de miniaturisation, les nanosciences ont connu un essor fulgurant lors de la dernière décennie. Au sein de ces dernières, les procédés lithographiques – clé de voûte de l’industrie des semi-conducteurs – permettent désormais d’accéder à des nanomatériaux fonctionnels. Malgré les récents développements technologiques, l’obtention de nanostructures possédant une résolution inférieure à 100 nm reste un défi majeur pour la communauté scientifique.Devant l’intérêt grandissant de développer des méthodes alternatives en nanolithographie, notre groupe s’est tourné vers une approche chimique, nommée nanolithographie par sonde locale catalytique (cSPL). Combinant la robustesse de la catalyse organométallique et la flexibilité offerte par la microscopie à sonde locale, notre stratégie permet la nanostructuration de surfaces organominérales par la création de liaisons covalentes dans des conditions douces. Cette approche innovante constitue le premier exemple d’immobilisation d’un catalyseur homogène à la surface d’une pointe d’un microscope à force atomique (AFM), dans l’optique de contrôler spatialement une réactivité chimique, l’époxydation localisée d’alcènes terminaux. Ces fonctions époxydes ont été employées comme points d’ancrage dans la nanostructuration à façon de surfaces de silicium avec une large variété de nucléophiles. De plus, l’optimisation des paramètres physico-chimique influant sur la réaction, a permis d’atteindre des résolutions latérales de l’ordre de 40 nm et laisse entrevoir de nombreuses perspectives dans la nanostructuration tridimensionnelle de matériaux organiquesIn regard to the constant quest for miniaturization, the field of nanosciences has known a tremendous expansion over the last decade. More precisely, lithographic technologies - key processes for the semi-conductor industry – allow to access to functional nanomaterials. Despite recent technological developments, the synthesis of nanostructures with a sub-100 nm resolution remains a major challenge for the scientific community.Due to the growing interest in the design of new nanolithographic methods, our group has focused its efforts on the development of a chemical approach, named catalytic scanning probe lithography (cSPL). Unifying the robustness of organometallic catalysis and the flexibility offered by scanning probe microscopy, our strategy allows the nanostructuration of organomineral surfaces in a soft controlled manner by the formation of covalent bonds. This innovative approach represents the first example of the immobilization of an homogeneous catalyst on the edge of an atomic force microscope (AFM) tip, in order to spatially control a chemical reaction: the localized epoxidation reaction of terminal alkenes. Those epoxides were then used as anchoring sites, in the nanostructuration of silicon wafers with a broad range of nucleophiles. Moreover, the different physico-chemical parameters influencing the reaction were optimized, allowing us to reach lateral resolutions down to 40 nm and opening new perspectives in the field of 3D-nanostructuration of organic materials
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Hassan, Safaa. "Optical Property Study of 2D Graded Photonic Super-Crystals for Photon Management." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703318/.
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In this dissertation, we study the optical property of 2D graded photonic super-crystals (GPSCs) for photon management. We focused primarily on manipulation and control of light by using the newly discovered GPSCs which present great opportunity for electromagnetic wave control in photonic devices. The GPSC has been used to explore the superior capability of improving the light extraction efficiency of OLEDs. The enhancement of extraction efficiency has been explained in term of destructive interference of surface plasmon resonance and out-coupling of surface plasmon through phase matching provided by GPSC and verified by e-field intensity distributions. A large light extraction efficiency up to 75% into glass substrate has been predicted through simulation. We also study the light trapping enhancement in GPSCs. Broadband, wide incident angle, and polarization independent light trapping enhancement is achieved in silicon solar cells patterned with the GPSCs. In addition, novel 2D GPSCs were fabricated using holographic lithography through the interference lithography by two sets of multiple beams arranged in a cone geometry using a spatial light modulator (SLM). Finally, we also report a fabrication of GPSCs with a super-cell size of 12a×12a by using e-beam lithography. Diffraction pattern from GPSCs reveals unique diffraction properties. In an application aspect, light emitting diode arrays can be replaced by a single light emitting diode shinning onto the diffraction pattern for a uniform fluorescence.
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Dumas, Carine. "Synthèse par implantation ionique, adressage, caractérisations électriques et optiques d'un nombre réduit de nanocristaux de Si dans SiO2." Toulouse, INSA, 2008. http://eprint.insa-toulouse.fr/archive/00000248/.
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Ce travail est consacré à la synthèse localisée et contrôlée de nanocristaux de Si dans une couche de SiO2 (<10 nm) par deux techniques d’implantation ionique. D’une part, l’implantation ionique à basse énergie (1keV) suivie d’un recuit thermique (ULE-II) permet d’élaborer un plan de nanocristaux dans une couche d’oxyde, d’autre part l’ULE-II couplée à la lithographie stencil (méthode originale SMULE- II) permet de les synthétiser localement et de contrôler leur nombre. Les caractérisations par MEB, AFM, EFTEM, spectroscopie de photoluminescence permettent l’étude structurale des nanocristaux (taille, forme, densité, position dans l’oxyde, caractéristiques des zones implantées localement…). Puis, des capacités MOS de taille micro à nanométrique en adressent un certain nombre (grand 108 à réduit 50). Les études I-V et I-t réalisées à température ambiante mettent en évidence des effets de chargement collectif (nanocristaux adressés en grand nombre ou connectés) et discret (nanocristaux en faible nombre (<200) ou formés localement et oxydés). Un modèle électrique permet de corréler les caractéristiques électriques et structurales. De plus, les études I-V réalisées à basse température et les mesures KFM confirment que les charges sont certainement stockées préférentiellement dans les nanocristaux. Pour finir, les effets de stockage de charge des mesures C-V confirment l’intérêt des nanocristaux de Si (élaborés par ULE-II ou SM-ULE-II) pour des dispositifs mémoires non volatiles, et les électrodes transparentes (ITO et ZnO) prouvent qu’il sera possible de les exciter optiquement et de les adresser électriquement afin de réaliser des dispositifs électro-optiquesThis work is dedicated to the localized synthesis of a controlled number of Si nanocrystals into SiO2 layer, by two ion implantation methods. On the one hand, the ultra low energy ion implantation followed by thermal annealing (ULE-II) leads to create a two dimensional array of nanocrystals ; On the other hand, the original SM-ULE-II method where ULE-II is performed through a stencil mask leads to fabricate localized areas of Si nanocrystals while controlling their number. Characterizations by SEM, AFM, EFTEM, photoluminescence spectroscopy allow studying the structural properties of the nanocrystals (size, density, shape, localization into the oxide, implanted areas characteristics,. . ). Then, a reduced number of nanocrystals elaborated by ULE-II (108 to 50) or SM-ULE-II is addressed by a micro to nanometer MOS capacitor. Room temperature I-V and I-t measurements exhibit collective charging effects (large number of nanocrystals addressed or connected nanocrystals) and discrete charging effects (a few number of nanocrystals or nanocrystals elaborated by SM-ULE-II and oxidized). An electrical model relates the electrical and structural properties. I-V characterizations realized at low temperature and KFM measurements confirm charge storage essentially into nanocrystals. C-V curves prove that nanocrystals are attractive to non volatile memory applications, and using transparent electrode (ZnO or ITO), nanocrystals can be optically excited and electrically addressed in order to create electro optical components
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Matcheswala, Akil Mannan. "GOLD NANOSPHERES AND GOLD NANORODS AS LOCALIZED SURFACE PLASMON RESONANCE SENSORS." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/60.
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A novel localized surface plasmon resonance (LSPR) sensor that differentiates between background refractive index changes and surface-binding of a target analyte (e.g. a target molecule, protein, or bacterium) is presented. Standard, single channel LSPR sensors cannot differentiate these two effects as their design allows only one mode to be coupled. This novel technique uses two surface plasmon modes to simultaneously measure surface binding and solution refractive index changes. This increases the sensitivity of the sensor.
Different channels or modes can be created in sensors with the introduction of gold nanospheres or gold nanorods that act as receptor mechanisms. Once immobilization was achieved on gold nanospheres, the technique was optimized to achieve the same immobilization for gold nanorods to get the expected dual mode spectrum. Intricate fabrication methods are illustrated with using chemically terminated self assembled monolayers. Then the fabrication process advances from chemically silanized nanoparticles, on to specific and systematic patterns generated with the use of Electron Beam Lithography.
Comparisons are made within the different methods used, and guidelines are set to create possible room for improvement. Some methods implemented failed, but there was a lot to learn from these unsuccessful outcomes. Finally, the applications of the dual mode sensor are introduced, and current venues where the sensors can be used in chemical and biological settings are discussed.
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Zimmermann, Gregor. "Elektrische Charakterisierung PLD-gewachsener Zinkoxid-Nanodrähte." Doctoral thesis, Universitätsbibliothek Leipzig, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-61365.
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Die vorliegende Arbeit beschäftigt sich mit der elektrischen Charakterisierung von Zinkoxid-Nanodrähten, die mittels gepulster Laserablation (PLD) hergestellt wurden.
Ausgehend von den so generierten ZnO-Nanodraht-Ensembles werden Methoden zu deren elektrischer Untersuchung diskutiert und auf praktische Anwendbarkeit hin verglichen. Die entwickelten Methoden werden auf Ensembles von auf n-leitenden ZnO- und ZnO:Ga-Dünnschichten aufgewachsenen Phosphor-dotierten ZnO-Nanodrähten angewendet. Deren reproduzierbares, in Strom–Spannungs- (I–U-) Kennlinien beobachtetes diodenartiges Verhalten wird genauer beleuchtet.
Im Zusammenhang mit der elektrischen Charakterisierung einzelner ZnO-Nano-drähte werden experimentelle Methoden zur Vereinzelung und zur Kontaktierung der vereinzelten ZnO-Nanodrähte diskutiert. Dabei werden sowohl etablierte Methoden wie Elektronenstrahllithographie (EBL) als auch neue Techniken wie elektronen- und ionenstrahlinduzierte Deposition (EBID/IBID) und Strom–Spannungs-Rastersondenmikroskopie (I-AFM) behandelt und ihre Eignung für eingehende elektrische Untersuchungen und reproduzierbare Messungen analysiert.
Die geeignetsten Methoden werden schließlich eingesetzt, um spezifischen Widerstand sowie Ladungsträgermobilität und -dichte sowohl in nominell undotierten als auch in Aluminium-dotierten ZnO-Nanodrähten zu untersuchen und zu vergleichen. In der Ableitung der physikalischen Materialparameter aus den Messdaten wird dabei besonderes Augenmerk auf die Einbeziehung der geometrischen Besonderheiten der Nanodrähte gegenüber Volumenmaterial- und Dünnschichtproben gelegt. Im Zuge dessen wird unter anderem ein Modell für den elektrischen Widerstand in Nanodrähten mit ihrer Länge nach veränderlichem Querschnitt abgeleitet.
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Bezryadin, Alexey. "Réseaux de Microtrous, vortex et supraconductivité de surface." Phd thesis, Université Joseph Fourier (Grenoble), 1995. http://tel.archives-ouvertes.fr/tel-00308630.
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Nous présentons une étude expérimentale et théorique sur la nucléation et l'évolution de la supraconductivité au voisinage d'un microtrou dans une couche mince. Sous champ magnétique la température critique d'une couche perforée est plus élevée que celle d'une couche sans trou et montre deux types d'oscillations quan tiques.
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Jian-Yin, Huang. "Effects of SPM Servo on the Stereo Lithography." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2007200514190200.
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Huang, Jian-Yin, and 黃健尹. "Effects of SPM Servo on the Stereo Lithography." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/17978806219467103043.
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碩士國立臺灣大學
機械工程學研究所
93
This paper addresses the three-dimensional scanning probe microscopy (SPM). The previous research has shown that the servo controller imposes significant effect on the lithography. A good controller enables a uniform and precise lithography pattern. This research, as a continuation to the previous work, achieved three-degree-of-freedom control of the SPM PZT driver and was able to scratch various patterns on the sample such as lines, flats and pyramids with different algorithms. This research also demonstrated that many unexpected effect could be observed when conducting continuous marking. The debris piles up on the sides of the plow mark and is very difficult to clean. It is also demonstrated that cleaning the debris by repetitively scratching the surface is possible. In addition, the design procedure for a Mu-synthesis controller is also presented to achieve desired performance. The experimental results confirm the design specifications.
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Schuckman, Amanda Eileen. "Charge Transport through Organized Organic Assemblies in Confined Geometries." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9055.
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Organic molecules such as porphyrins and alkanethiols are currently being
investigated for applications such as sensors, light-emitting diodes and single electron
transistors. Porphyrins are stable, highly conjugated compounds and the choice of metal
ion and substituents bound to the macrocycle as well as other effects such as chemical
surrounding and cluster size modulate the electronic and photonic properties of the
molecule. Porphyrins and their derivatives are relatively non-toxic and their very rich
photo- and electro-chemistry, and small HOMO-LUMO gaps make them outstanding
candidates for use in molecularly-enhanced electronic applications.
For these studies, self-assembled tri-pyridyl porphyrin thiol derivatives have
been fully characterized on Au(111) surfaces. A variety of surface characterization
techniques such as Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy
(STM), FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) have been
implemented in order to obtain information regarding the attachment orientation based
on the angle and physical height of the molecule, conductivity which is determined
based on the apparent height and current-voltage (I-V) measurements of the molecule, conductance switching behavior due to conformational or other effects as well as the
stability of the molecular ensembles. Specifically, the transport properties of free base
and zinc coordinated tri-pyridyl porphyrin thiol molecular islands inserted into a
dodecanethiol matrix on Au(111) were investigated using STM and cross-wire inelastic
electron tunneling spectroscopy (IETS). The zinc porphyrin thiol islands observed by
STM exhibited reversible bias induced switching at high surface coverage due to the
formation of Coulomb islands of ca. 10 nm diameter driven by porphyrin aggregation.
Low temperature measurements (~ 4 K) from crossed-wire junctions verified the
appearance of a Coulomb staircase and blockade which was not observed for single
molecules of this compound or for the analogous free base. Scanning probe lithography
via nanografting has been implemented to directly assemble nanoscale patterns of zinc
porphyrin thiols and 16-mercapotohexadecanoic acid on Au surfaces. Matrix effects
during nanopatterning including solvent and background SAMs have been investigated
and ultimately ~ 10 nm islands of zinc porphyrins have been fabricated which is the
optimal size for the observed switching effect.
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Van, Niekerk G. J. "Intelligent STL file correction." Thesis, 2012. http://hdl.handle.net/10210/7041.
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M.Sc.Layered Manufacturing (LM), also known as "Rapid Prototyping", is that process in terms of which a computer-designed model is created layer by layer with the aid of specific LM hardware. Telemanufacturing constitutes an extension of this technology that allows remote submission of manufacturing jobs or assignments across a communication medium, typically the Internet, to be built at the manufacturing bureau concerned. The de facto standard of LM is the STL file. Simply put, this file consists of a number of triangles that are used to describe an object in its entirety. This file format has several advantages over other known formats and allows easy 2D rendering. Unfortunately, however, the limitations of the latter format outweigh its advantages. Since the entire model is described in terms of a collection of triangles, the original geometry of the model is lost. As a result, a certain level of degradation will occur, especially around curvatures in the model. Although an increase in the number of triangles around such areas will enhance precision, it will also result in a much larger STL file. Triangles that get lost somewhere inside the file could also give rise to holes, orphaned surfaces and zero-width walls in the projected object. It is vital, therefore, that the manufacturing bureau verify the correctness of the entire file before it is built in order to prevent machine time and materials from being wasted. Instead of transmitting the entire file again, the bureau could attempt automatically to correct and repair less critical errors, thereby saving valuable resources and time.