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Knight, Patrick J. "Nitride formation at silicon surfaces." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238903.
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Klaes, Stefan. "Photo-switching of organic monolayers on silicon surfaces." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX071/document.
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La conception de surfaces "intelligentes" sensibles aux stimuli externes (lumière, champ électromagnétique, environnement chimique ...) attire un intérêt considérable en raison de leur potentiel pour une large gamme d'applications. Dans ce contexte, nous étudions les propriétés de transfert de photos d'une monocouche de photochromes organiques immobilisés sur des surfaces de silicium.Les groupes Fulgimide sont ancrés par liaison covalente au-dessus de monocouches alkyliques fonctionnalisées greffées sur des surfaces Si (111) exemptes d'oxyde. La composition des monocouches dans les états stationnaires photo EPS-UV et EPS-Vis est déterminée à partir de l'analyse quantitative de l'intensité de la bande infrarouge caractéristique des isomères ouverts (E, Z) et fermés (C). La photocommutation de surface UV-Vis est surveillée par des mesures infrarouge à transformée de Fourier in situ en temps réel lors de l'éclairage UV-Vis. Les études de dépendance temporelle de la photocommutation montrent une diminution de l'efficacité quantique pendant la commutation. Cette diminution de l'efficacité quantique dépend faiblement de la densité de fulgimide et n'est pas observée en solution. Cependant, les mesures de PC en fonction du flux de photons ont permis de déterminer une section efficace de la PC (σ) de la majorité des molécules commutables. Les études de photocommutation dépendantes de la polarisation montrent une forte dépendance de σ par rapport au champ électrique local de la lumière excitante d'isomérisation.Les modèles analytiques et les simulations de Monte Carlo basées sur les interactions des voisins les plus proches sont effectuées pour obtenir une meilleure compréhension des observations expérimentales. Ces simulations expliquent qualitativement la dépendance à la température de la cinétique de commutation, diminuant l'efficacité quantique et la faible densité de surface de la photocommutation.Il a été montré dans cette thèse que σ dépend du champ électrique local. À l'instar de la spectroscopie Raman améliorée en surface, le champ électrique local sur les surfaces augmente en raison du plasmon des nanoparticules d'or. Le plasmon de la monocouche de nanoparticules d'or et ainsi l'amélioration du champ électrique dépend de la longueur d'onde de l'irradiation externe. L'exploitation de cet effet améliore significativement la cinétique de la commutation en fonction de la longueur d'onde de l'irradiation. Cette amplification dépendant de la longueur d'onde de la cinétique de la commutation s'explique par la même amplification dépendante de la longueur d'onde du champ électriqueThe design of “smart” surfaces responsive to external stimuli (light, electromagnetic field, chemical environment…) is attracting considerable interest because of their potential for a wide range of applications. Within this context we are studying the photoswitching properties of a monolayer of organic photochromes immobilized onto silicon surfaces.Fulgimide groups are anchored through covalent linkage atop of functionalized alkyl monolayers grafted on oxide free Si(111) surfaces. The monolayers composition at the photo stationary states PSS-UV and PSS-Vis is determined from quantitative analysis of the infrared band intensity characteristic of open (E,Z) and closed (C) isomers. The UV-Vis surface photocommutation is monitored by in-situ real time FTIR measurements during UV-Vis illumination. Time dependence studies of photocommutation evidence decreasing quantum efficiency during the commutation. This decrease in quantum efficiency only weakly depends on fulgimide density and is not observed in solution. However, PC measurements as a function of photon flux enabled determining a PC cross section (σ) of the majority of switching molecules. Polarization dependent photocommutation studies show the strong dependence of σ with respect to the local electric field of the isomerization-exciting light.Analytical models and Monte Carlo simulations based on nearest neighbor interactions are performed to gain deeper insight in the experimental observations. These simulations qualitatively explain the temperature dependence of the commutation kinetics, decreasing quantum efficiency and weak surface density dependence of the photocommutation.It has been shown in this thesis that σ depends on the local electric field. Similar to the Surface Enhanced Raman Spectroscopy the local electric field at surfaces is increased due to the plasmon of gold nanoparticles. The plasmon of the gold nanoparticle monolayer and thereby the enhancement of the electric field depends on the wavelength of the external irradiation. Exploitation of this effect improves the photo switching kinetics significantly depending on the wavelength of the irradiation. This wavelength dependent amplification of the switching kinetics is explained by the same wavelength dependent enhancement of the electric field
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Gibbons, Brian J. "Electromigration induced step instabilities on silicon surfaces." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1143235175.
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Thirtle, P. N. "Neutron reflection from modified silicon surfaces." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301731.
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King, David J. "Modelling of fullerenes on silicon surfaces." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/4644.
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An extension to the capabilities of an ab-initio density functional theory package, PLATO, has been undertaken. This concerned the calculation of Slater-Koster integrals and their derivatives, via the recursive methods initially proposed by Podolskiy and Vogl, and developed by Elena and Meister. This extension provides the ability to include the previously unavailable f -orbitals (and beyond) within PLATO calculations. Calculations have been performed, including f - orbitals, on silver, silicon and nitrogen systems. The results show a modest improvement, in terms of the convergence of the total energies calculated, when comparing the calculations including f -orbitals to those without. The impact on computational time is mixed, with both decreases and increases in compuational time demonstrated, dependent on the system in question and the type of calculation performed. The interactions between C60 molecules and the Si (100) surface, as well as the interactions between the endohedrally doped N@C60 molecules and the Si (100) surface have been explored via ab-initio total energy calculations. Configurations which have the cage located upon the dimer row bonded to two dimers (r2) and within the dimer trench bonded to four dimers (t4) have been investigated, as these have previously been found to be the most stable for the C60 molecule. We show that our results for the adsorption of the C60 molecule upon the Si (100) surface are comparable with previous studies. We have investigated the differences between the adsorption of the C60 and N@C60 molecules upon the Si (100) surface and found that there are only minimal differences. It is shown that the effects on the endohedral nitrogen atom, due to its placement within the fullerene cage, are small. Bader analysis has been used to explore differences between the C60 and N@C60 molecules. The interactions between pairs of C60 molecules adsorbed upon the Si (100) surface have also been studied. The same selection of t4 configurations used for the isolated fullerenes is explored in all possible pairs of fullerene configuration combinations. A previous study by Frangou explored pairs of fullerenes in adjacent bonding sites on the silicon surface, this study, however, investigates bonding sites separated by one silicon dimer. Comparisons between the two studies confirm the trend of the combinations becoming more favourable at a greater fullerene separation. There are several cases where the combined pair of fullerenes are less favourable than the two isolated cases, so these are studied indepth. The separation chosen in our study reflects the experimental separation observed by Moriarty et al..
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Frangou, Paul Christopher. "Modelling of fullerenes on silicon surfaces." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/13499.
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The interactions between fullerene cages and Si {100) surfaces are studied using density functional theory. This has previously been studied and the molecules are found to bind in four different locations upon the dimerised Si (100) surface. These are above the dimer row bound to one or two dimers (rl and r2 respectively) and within the dimer trench bound to two or four dimers (t2 and t4 respectively). Here we focus on the r2 and t4 configurations as these were found to have stronger binding energies due to the four bonds forming between cage and surface rather than two. The rl and t2 sites are actually metastable and minor displacements of the cages result in them falling in to one of the energy minima of the t4 and r2 sites. All of the configurations discovered by Godwin et al. via PLATO, are verified as are three of the additional configurations from the study by Hobbs et al. which used the SIESTA software package. A more complete basis set is employed here to ascertain the effect it has upon the basis set superposition error. It is found to reduce it to negligible levels.
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Wilson, Jon H. "Silicon surfaces : STM, theory and experiment." Thesis, University of Oxford, 1991. http://ora.ox.ac.uk/objects/uuid:64998ae3-9316-42b5-967f-da93ff2bfd6c.
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The fundamental atomic and electronic behaviour of clean silicon surfaces has been studied within a simple tight-binding picture of bonding in solids. Of the various contributions to the surface binding energy, the lowering in the promotion energy (i.e. rehybridization) which accompanies localized Jahn-Teller distortions has been identified as a major electronic driving force underlying the stability of silicon surfaces. The structure of Si(113) has been experimentally determined by the technique of scanning tunnelling microscopy (STM). Despite its high index, the Si(113) surface is found to be highly stable. STM images of both empty and filled states provide strong evidence for a particular structural model with a 3x2 unit cell. The STM results are explained in terms of a general rehybridization principle, suggested by the earlier theoretical study, which accounts for the low surface energy as well as the observed spatial distribution of empty and filled states. In addition, the STM images reveal a high density of domain boundaries which introduce energy states that pin the Fermi level and explain earlier reports of a 3x1 reconstruction for this surface. Voltage-dependent STM image simulations for the Si(113)3x2 surface have been carried out using a simple tight-binding description of surface electronic structure. Quantitative agreement with experiment is obtained confirming the qualitative rehybridization arguments used previously. The local barrier for tunnelling electrons is shown to have an important effect on the interpretation of STM images. The high stability of clean Si(l 13) is shown by STM to be disrupted by adsorption of submonolayer amounts of atomic hydrogen which saturates dangling bonds. Mass transport of silicon occurs and structural models are proposed for the resultant mixed 2x2 and 2x3 surface.
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Lindsay, Robert. "Structure of adsorbates on silicon surfaces." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385261.
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Ramstad, Monte Jerome. "Instabilities of vicinal silicon (111) surfaces." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/42571.
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Harte, Sean Paul. "Surface EXAFS studies of chromium and titanium upon #alpha#-quartz (0001) surfaces." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263901.
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In this thesis two studies of reactive metal adsorption upon a low index single crystal silicon dioxide surface are presented in addition to a study of sulphur adsorption upon a low index single crystal nickel surface. Chromium growth upon the a-quartz Si02(0001) (J84xJ84) Rll 0 surface is studied at three coverages, 0.25±O.08 ML, 0.5±O.16 ML and 1.0±0.33 ML, using surface extended x-ray absorption fine structure (SEXAFS). SEXAFS measurements, from the chromium K-edge, recorded at both grazing and normal incidence show that chromium growth proceeds via the formation of mesoscopic particles with a body centred cubic (b.c.c.) like structure having an average nearest neighbour Cr-Cr distance of 2.36±O.03 A. This represents a contraction of 5.6 % from the bulk b.c.c. lattice spacing of 2.49 A. There is no evidence of a surface reaction between chromium and the surface oxygen. SEXAFS was used to study titanium reactional growth on a-quartz (0001) (J84xJ84) Rll 0 and (lx1). Three nominal coverages were studied, 0.25±O.08 ML, 0.5±O.16 ML and 1.0±O.33 ML. Both normal and grazing incidence SEXAFS data were recorded and show the formation of a spatially extensive region in which an interfacial reaction has occurred between surface oxygen and adsorbate titanium atoms. Coupled with this is the formation of subnanometre titanium clusters. The metal oxide has nearest neighbour Ti-O distances close to those of both the anatase and rutile forms of titania with the metallic titanium clusters having a Ti-Ti distance within experimental error that of bulk hexagonal close packed (h.c.p.) titanium, 2.89 A. A re-examination of the surface geometry of Ni(1l0)c(2x2)S using SEXAFS has been performed. Data out to an electron wavevector of 9 A-I are analysed with a new code to assess the influence of multiple scattering. The first shell S-Ni distance is determined to be 2.20±O.02 A with the next nearest neighbour distance being 2.29±O.02 A, giving a top-layer Ni expansion of 14±3% relative to the bulk. The influence of multiple scattering does not significantly alter these values from earlier studies.
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Hui, I. Pui, and 許貽培. "Positron re-emission from silicon carbide surfaces." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227387.
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Nolan, John William. "Contacting and imaging nanostructures on silicon surfaces." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275970.
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Luginbühl, Reto. "Photobonding of biomacromolecules to Silicon Nitride surfaces /." [S.l.] : [s.n.], 1997. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Lawing, Andrew S. (Andrew Scott). "Gas-phase cleaning of silicon wafer surfaces." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/38852.
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Burr, Tracey Alexandra 1967. "Electrical properties of silicon surfaces and interfaces." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9689.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.Includes bibliographical references (p. 159-168).
This work addresses two scientific challenges associated with diminishing device size. First, alternative surface passivation chemistries are investigated to meet the narrowing process tolerances for high quality silicon surfaces. Second, Si-based light emitting devices are studied to address a longer-term move towards photons instead of electrons for data transfer. A concerted effort is made to engineer environmentally benign solutions to these challenges. Highly effective Si( 100) surface passivation is achieved by immersing wafers in very dilute solutions of methanolic iodine. The electrical quality of Si surfaces is monitored in terms of surface recombination lifetime, employing radio frequency photo conductance decay (rfPCD) measurements. J/methanol treated surfaces are shown to have higher lifetimes and greater air stability than hydrogen terminated surfaces, while retaining comparable planarity and smoothness. Using XPS, UPS, and ATR-FTIR, the identity of the primary passivating surface species is ascertained to be a methoxysilane (Si-OCH3), and the most plausible passivation mechanism is deduced. Our results clearly illustrate the relationship between chemical passivation and electrical passivation. Thin films of visibly emitting silicon nanoparticles are fabricated using a pulsed laser ablation supersonic expansion technique. The electrical and electroluminescence characteristics of devices containing these films are shown to be controlled by carrier transport through the nanoparticulate silicon layer. A conduction mechanism encompassing both geometric and electronic effects most effectively relates the high resistivity with structural properties of the films. The observed temperature dependent PL, EL, and I-V characteristics of the devices are consistent with a model in which carrier transport is controlled by space-charge-limited currents or tunneling through potential barriers on a percolating lattice.
by Tracey Alexandra Burr.
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Gibbons, Brian J. Jr. "Electromigration induced step instabilities on silicon surfaces." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1143235175.
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Liu, Yong. "Desorption kinetics of surface species on Si(100)2X1 and Si(111)7X7 surfaces : theoretical and digital TPD studies." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239634.
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Silaghi, Simona Dorina. "Optical Characterisation of DNA Bases on Silicon Surfaces." Doctoral thesis, Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200500776.
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Im Rahmen dieser Arbeit werden DNA-Basen-Moleküle (Thymin, Cytosin, Adenin und Guanin) auf H-passivierten Si(111)-Substraten mittels theoretischer Berechnungen und optischen Spektroskopien charakterisiert. Für ein einzelnes DNA-Basen-Molekül wurden quantenchemische Berechnungen von Elektronenübergängen und vibronischen Moden durchgeführt. Zusätzlich wurden die vibronischen Eigenschaften von Metall(Ag,In)/Cytosin-Komplexen sowie die Adsorption von einzelnen Cytosin-Molekülen auf H:Si(111)-Oberflächen studiert.
Die biomolekularen Schichten von DNA-Basen wurden durch organische Molekularstrahldeposition (OMBD) im Ultrahochvakuum auf flachen und vicinalen H:Si(111)-Oberflächen hergestellt. Die Morphologie, Struktur und Kristallinität von DNA-Basen-Schichten wurden mittels Rasterkraftmikroskopie (AFM), Röntgenbeugung (XRD) und Röntgenreflektometrie (XRR) charakterisiert. Die Vibrationseigenschaften von biomolekularen Schichten wurden experimentell durch Infrarotspektrokopie untersucht. Metall(Ag,In)/Cytosin/H:Si(111)-Heterostrukturen wurden mittels oberflächenverstärkter Ramanstreuung (SERS) charakterisiert. In dieser Arbeit wurden erstmals die optischen Konstanten und die dielektrischen Funktionen von dicken DNA-Basen-Schichten auf ebenen H:Si(111)-Oberflächen mittels spektroskopischer Ellipsometrie (SE) bestimmt. Ebenfalls zum ersten Mal wurden dünne biomolekulare Schichten auf vicinalen H:Si(111)-Oberflächen durch Reflektionsanisotropiespektroskopie (RAS) charakterisiert.
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Xie, Bo. "Supercritical Carbon Dioxide Processing of Silicon Wafer Surfaces." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1207%5F1%5Fm.pdf&type=application/pdf.
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Taylor, Michael Dennis Robert. "A study of nanoscale clusters on silicon surfaces." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288104.
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Nasir, Mazhar Ejaz. "Fabrication and spectroscopy of nanostructured surfaces on silicon." Thesis, University of Manchester, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677177.
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Willis, Mary L. "STM Studies of Oxygen Etching of Silicon Surfaces." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1008.
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This study uses atomic force microscopy (AFM) to investigate the oxygen etching behavior of the following silicon surface orientations: (001), (111), (113), (5 5 12) and (112). Most etching was performed at sample temperatures between 650 °C and 800 °C, at pressures of 3.3×10-7 and 1.5×10-7 Torr, and at an exposure of 200 L. Surface orientation strongly influences the morphology resulting from extended etching. The surface orientations that are stable against etching and remain flat include Si(001), Si(111), and Si(113). Such surfaces also include island structures, which result from etching around oxide-induced pinning sites. The density of these islands increases at lower temperatures and higher pressures. The surface orientations that are unstable against oxygen etching and facet to other orientations include Si(5 5 12) and Si(112). These surfaces form sawtooth facets that are primarily composed of more stable (111) and (113) planes. By controlling the temperature and exposure during oxygen etching, it is therefore possible to form a variety of surface morphologies.
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Butcher, Matthew James. "Adsorption and manipulation of doped fullerenes on silicon surfaces." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325717.
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Gold, Scott Alan. "Nitrogen incorporation in thin silicon oxide films for passivation of silicon solar cell surfaces." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/11101.
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Ngan, Mei Lun. "Photoluminescence excitation of porous silicon." HKBU Institutional Repository, 1998. http://repository.hkbu.edu.hk/etd_ra/139.
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Jiang, Guilin. "Characterization, Functionalization and Applications of Alkyl Monolayers on Silicon Surfaces." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1073.
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Investigations were performed on the stability, mechanism of formation and an application of alkyl monolayers chemomechanically prepared on silicon surfaces. A new method of surface modification, laser-activation modification of surfaces (LAMS), and multivariate analyses of time-of-flight secondary ion mass spectrometry (ToF-SIMS) images of LAMS spots were also reported. X-ray photoelectron spectroscopy (XPS) and other data show that alkyl monolayers prepared by scribing silicon under 1-iodoalkanes and 1-alkenes were stable over extended periods of time to air, water, a boiling acid and Al Ka X-rays. The stability is attributed to direct Si-C bonding in the monolayers. The observation that the oxygen signals gradually increased and the iodine signals gradually decreased, with both finally reaching plateaus is attributed to the oxidation of exposed silicon by scribing, and the hydrolysis of Si-I bonds, respectively. In alkyl monolayers prepared with 1-alcohols, the carbon signals decreased about 50% after two 1-h immersions in a boiling acid, suggesting unstable Si-O bonding. In the analogous experiment of grinding silicon with alkyl halides, the expected free-radical combination and disproportionation byproducts were observed. This observation provides evidence for the mechanism previously proposed for alkyl monolayer formation on silicon by chemomechanically scribing. Miniaturized sample supports for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were made on hydrophobic silicon or glass surfaces by scribing. With these sample supports, improved MALDI-MS signal intensities and reproducibilities were achieved for a test peptide, as expected. A new and promising method for surface modification, LAMS, was developed. XPS and ToF-SIMS analyses show that both silicon and germanium were effectively modified by LAMS with even quite inert compounds. This technique was also used to make miniaturized MALDI-MS sample supports. Compared to scribing, LAMS is faster and can be more precisely controlled. Multivariate analyses, automated expert spectral image analysis (AXSIA) and principal component analysis (PCA), were used in interpreting ToF-SIMS images of silicon surfaces modified with 1-alkenes by LAMS. Both analyses show that modified and unmodified areas are chemically different.
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Pavlovic, Elisabeth. "Spatially Controlled Covalent Immobilization of Biomolecules on Silicon Surfaces." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3523.
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Römhildt, Lotta. "Biochemical functionalization of silicon dioxide surfaces for sensing applications." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-148666.
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The aim of this work was to functionalize silicon dioxide surfaces with biochemical molecules in such a way that biorecognition of target molecules in solution will be possible. By introducing a tool set of different molecules and characterization methods, a more universal approach towards various biosensor setups is presented. This includes on the one hand preparation of the biosensor surfaces to allow further molecule attachment via their reactive functional groups. Secondly, the selection of chemical molecules providing suitable counterparts for abundant functional groups of potential receptors is discussed. Two detection schemes are introduced – based on an antibody to detect the antibiotic amoxicillin and aptamers to detect thrombin. The antibody was implemented in an inverse competition assay to probe such small target molecules. Antibiotic residues are often present in wastewater. Aptamers, so-called artificial antibodies, were selected as they provide many advantages over antibodies. As a model system, two different thrombin binding aptamers were chosen which allowed to perform sandwich assays as well. The protein thrombin plays an important role in the blood coagulation cascade. To probe the individual modification steps, different techniques for analysis were applied. Surface micropatterning was introduced to improve recognition of modified areas and fluorescence-to-background ratios resulting in a thrombin detection limit down to 20 pM. One important goal was the integration in ion-sensitive field-effect transistor devices. Aptamers are small in size which might enable a higher sensitivity of these devices compared to the use of antibodies because of the Debye layer thickness. As a final step, first measurements towards silicon nanowire based field-effect transistor biosensors were carried out on devices with bottom-up and top-down fabricated nanowires using both proposed receptor-analyte combinations. The potential of these devices as portable sensors for real-time and label-free biosensing is demonstratedZiel dieser Arbeit war es Siliziumdioxidoberflächen so mit biochemischen Molekülen zu funktional- isieren, dass die biologisch spezifische Erkennung von Zielmolekülen in Lösung möglich wird. Hier wird eine Auswahl an geeigneten Molekülen und Charakterisierungsmethoden für einen vielseitigen Ansatz gezeigt, der auf verschiedene Biosensorsysteme anwendbar ist. Das beinhaltet zum Einen die Präparation der Biosensoroberflächen, so dass die Moleküle über reaktive funktionelle Gruppen angebunden werden können. Als zweites ist die Auswahl der chemischen Moleküle wichtig, da diese die passenden Gegenstücke zu potentiellen funktionellen Gruppen der Rezeptoren darstellen. Zwei verschiedene Detektionsvarianten werden eingeführt – Antikörper gegen das Antibiotikum Amoxicillin und Aptamere gegen Thrombin. Der Antikörper wurde in einen inversen Wettbewerbsassay integriert um einen solch kleinen Ana- lyten detektieren zu können. Rückstände von Antibiotika sind häufig in Abwässern zu finden. Ap- tamere, sogenannte künstliche Antikörper, weisen gegenüber Antikörpern viele Vorteile auf. Als ein Modellsystem wurden zwei unterschiedliche Thrombin bindende Aptamere verwendet, was auch die Durchführung von Sandwich Assays ermöglichte. Das Protein Thrombin spielt eine wichtige Rolle bei der Blutgerinnung. Um die einzelnen Modifikationsschritte zu untersuchen, wurden verschiedene Charakterisierungsmethoden angewendet. Die Mikrostrukturierung der Funktionalisierung erleichterte die Erkennung der modifizierten Flächen und verbesserte das Fluoreszenz-zu-Hintergrund Verhältnis. Das führte zu einer Detektionsgrenze von 20 pM für Thrombin. Ein wichtiges Ziel dieser Arbeit war die Integration der Funktionalisierung in einen ionen-sensitiven Feldeffekttransistor. Die kleinen Aptamere könnten dabei aufgrund der geringen Debye-Schichtdicke bei diesen Sensoren eine höhere Sensitivität als mit Antikörpern ermöglichen. Zuletzt wurden erste Messungen hin zu Silizium Nanodraht basierten Feldeffekttransistor Biosen- soren mit beiden untersuchten Rezeptor-Analyt-Kombinationen durchgeführt. Sowohl die Chips mit bottom-up als auch mit top-down gewachsenen Nanodrähten zeigen dabei ihr Potential als handliche Sensoren zur markerfreien Detektion in Echtzeit
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Upward, Martin David. "Fullerenes, transition metal clusters and organometallics on silicon surfaces." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267153.
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Lee, Michael V. "Development of chemomechanical functionalization and nanografting on silicon surfaces /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2023.pdf.
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Lee, Michael Vernon. "Development of Chemomechanical Functionalization and Nanografting on Silicon Surfaces." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1435.
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Progress in chemomechanical functionalization was made by investigating the binding of molecules and surface coverage on the silicon surface, demonstrating functionalization of silicon with gases by chemomechanical means, analyzing atomic force microscopy probe tip wear in atomic force microscopy (AFM) chemomechanical nanografting, combining chemomechanical functionalization and nanografting to pattern silicon with an atomic force microscope, and extending chemomechanical nanografting to silicon dioxide. Molecular mechanics of alkenes and alkynes bound to Si(001)-2x1 as a model of chemomechanically functionalized surfaces indicated that complete coverage is energetically favorable and becomes more favorable for longer chain species. Scribing a silicon surface in the presence of ethylene and acetylene demonstrated chemomechanical functionalization with gaseous reagents, which simplifies sample cleanup and adds a range of reagents to those possible for chemomechanical functionalization. Thermal desorption spectroscopy was performed on chemomechanically functionalized samples and demonstrated the similarity in binding of molecules to the scribed silicon surface and to the common Si(001)-2x1 and Si(111)-7x7 surfaces. The wearing of atomic force microscope probe tips during chemomechanical functionalization was investigated by correlating change over time and force with widths of created lines to illustrate the detrimental effect of tip wear on mechanically-driven nanopatterning methods. In order to have a starting surface more stable than hydrogen-terminated silicon, silicon reacted with 1-octene was used as a starting surface for AFM chemomechanical functionalization, producing chemomechanical nanografting. Chemomechanical nanografting was then demonstrated on silicon dioxide using silane molecules; the initial passivating layer reduced the tip friction on the surface to allow only partial nanografting of the silane molecules. These studies broadened the scope and understanding of chemomechanical functionalization and nanografting.
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Han, Yong-Pil 1962. "HF vapor etching and cleaning of silicon wafer surfaces." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/32698.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1999.Includes bibliographical references.
The objectives of this project are to understand the reaction mechanisms for oxide etching by both HF/H2 0 and HF/alcohol processes and to develop a vapor phase HF cleaning process to remove metallic contamination and native oxide on a silicon surface. Although the HF vapor process has been studied intensively for past several decades, the commercial application has not been very successful due to the unknown nature of the process. This study, performed at MIT, has emphasized on finding possible applications to the semiconductor industry as a replacement to the aqueous phase cleaning processes. The ultimate purpose of this project is to demonstrate feasibility of the HF vapor process for a vacuum compatible and clustered cleaning process. In this study, the etching experiments were carried out in a stainless steel vacuum chamber connected to a vacuum wafer transfer system. Samples were introduced through a load lock chamber and transferred to the HF vapor reaction chamber. The base pressure of the system was maintained under 10-7 Torr. The system can handle sample sizes between 1 cm square and 10 cm diameter silicon wafers. The etching rates were measured by an in situ ellipsometer installed on the HF vapor reactor. Ellipsometric measurements suggest that oxide etching can occur without a condensed layer or with a condensed layer on the oxide surface. The etching rates of oxide in the condensed regime were very high (3,000-12,000 A/min) compared to the gas phase regime (0-300 A/min). The etching regime in which a condensed layer is formed is a function of not only the partial pressures of HF and H 20 in the feed gas, but also a function of the mass transport of the products from the sample in the gas phase. We have categorized two different etching regimes: the gas phase regime and the condensed phase regime. In the gas phase etching regime, reactant molecules are adsorbed on the oxide surface in sub-monolayer, monolayer, or multilayer films. In the multilayer adsorption regime, the etching rate is usually low (typically 0-400 A/min) and is linearly proportional to the partial pressure of HF and H20. The etching rate in this regime is greatly affected by the temperature of the substrate. The mass transfer rate limits the etch rate of oxide in the multilayer adsorption regime. In the submonolayer or monolayer adsorption regime the etching rate is described by Langmuir- Hinshelwood kinetics. The etching rate is governed by surface kinetics in this regime. Advantages of this etching regime are: 1) smoother etched surface, 2) low selectivity to TEOS, 3) haze-free etched surface, 4) no metal attack, 5) perfect removal of native oxide, and 6) vacuum compatible process. The HF vapor process in this regime is an ideal process for contact cleaning and polymer removal after metal or via etching. Electrostatic charge on the wafer surface affects the etching reaction significantly in the non-condensed regimes. A positively charged surface enhanced the etching reaction in the submonolayer and monolayer etching regimes. Direct ionization of HF on the oxide surface is responsible for the enhancement in this regime. A negatively charged surface mainly enhanced the etching in the multilayer regime. A thicker multilayer, induced by the formation of fluorosilicate, is responsible for the etching enhancement in this regime. We have demonstrated a successful removal of sodium from both oxide and silicon surfaces using HF/H2 0, HF/IPA, and HF/H20/SiF4 processes in reduced pressure operation. All experiments were performed in a vacuum environment and in-situ XPS was used to measure the surface concentration of sodium. The sodium contamination on oxide surface was successfully removed by both HF/H 20 and HF/IPA processes. The HF/H 20 process could not remove all of sodium contamination on a silicon surface. The addition of SiF4 in the HF/H 20 process greatly enhances the cleaning effect, reducing Na contamination below the detection limit of our XPS, even on a silicon surface. Based on our study, we have reported a true gas phase and vacuum compatible HF vapor process, operated in the monolayer adsorption regime at elevated temperature. A successful removal of RIE residue was performed with a combined cleaning procedure of HF vapor and ashing process. This combined process is a perfect dry cleaning process for contact cleaning method. This process sequence is ideal for a vacuum cluster configuration in which a single wafer is processed at a time and is not exposed in the ambient.
by Yong-Pil Han.
Ph.D.
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Abdualla, Mufida. "Sythesis and characterisation of ferrocenyl monolayers on silicon surfaces." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2445.
Full textAbstract:
A series of ferrocenyl monolayers on hydrogen-terminated Si(111) single crystal and porous silicon have been prepared and characterised by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Hydrosilylation modification of hydrogen-terminated Si(111) single crystal and porous silicon with vinylferrocene and ethynylferrocene was shown to produce three different silicon–carbon tethered ferrocenyl surfaces, Si-CH₂-CH₂-Fc, Si-CHCH-Fc, and Si-CC-Fc. Three different grafting procedures were used, a thermally activated method at 110 C in toluene using vinylferrocene produced the Si-CH₂-CH₂-Fc monolayer, EFc. Hydrosilylation at room temperature using ethynylferrocene in the minimum amount of dichloromethane produced the Si-CHCH-Fc surface, VFc. Finally, the reaction of n-butyllithium with ethynylferrocene via a nucleophilic substitution reaction (acetylide anion) at the silicon hydride electrode produced the Si-CC-Fc surface, EnFc. Transmission FTIR analysis confirmed that three different linkages were formed on porous silicon. Data recorded using cyclic voltammetry showed that ferrocenyl silicon monolayers were more stable in acetonitrile than aqueous electrolyte. The maximum surface coverage measured in acetonitrile was 1.3×10-¹º mol cm-₂ for the EFc surface, 2.7×10-11 mol cm-₂ for the VFc surface, and 5.4×10-¹¹ mol cm-₂ for the EnFc surface. However, reproducibility of the EFc, VFc and EnFc surfaces was not easy to control. In order to find a way to improve reproducibility, a series of 50:50 mixtures of vinylferrocene and simple alkenes were investigated. The alkenes used for this purpose were hexene (EFc/C₆), octene (EFc/C₈), decene (EFc/C₁₀), and undecene (EFc/C₁₁). AFM, XPS and CV were used to analyse these surfaces. Different surface coverages for 50:50 mol:mol in bulk solution of EFc/C₆, EFc/C₈, EFc/C₁₀, and EFc/C₁₁ were obtained from CV in aqueous and acetonitrile electrolytes. Higher coverage was observed in acetonitrile than water for all 50:50 mixed monolayers, and the EFc/C₈ surface was the more reproducible surface with a surface coverage of 4.0×10-¹¹mol cm-². Therefore, a range of more dilute EFc/C₈ surfaces, 20:80, 10:90 and 1:99 were prepared via reaction with a vinylferrocene/octene mixture and characterised using AFM, XPS and CV. The cyclic voltammograms of dilute mixed monolayers EFc/C₈ gave different surface coverages in acetonitrile electrolyte. The average observed were 3.03×10-¹¹ mol cm-², 1.84×10-¹² mol cm-² and 7.95×10-¹³ mol cm-² for 20:80, 10:90 and 1:99 EFc/C₈ surfaces respectively. The coverage of mixed EFc/C₈ monolayers determined via CV was found to depend on the mole fraction of vinylferrocene in the initial alkylation solution, and it is possible to control the separation of ferrocene units on the silicon surface by controlling the mole fraction. In addition, longer alkyl chain linkages between the ferrocene and silicon surface were investigated by two different approaches. In the first approach a ferrocenyl group with an extended tether was first synthesised, 1-(but-1-en-3-yne)ferrocene, and was then attached as a complete unit to the silicon surface using a one-step reaction to give the BuFc surface. In the second approach, the ferrocene monolayer was built up from the silicon surface in a two-step reaction procedure. In the first step, the silicon hydride surface was modified with 5-iodo-3-ethyl-2-ethynylthiophene to give the Tp surface. In the second step, the Tp surface was coupled to ethynylferrocene via the Sonogashira reaction to give the TpFc surface. In XPS a new Fe 2p peak and the concurrent disappearance of the I 3d peak was observed for the TpFc surface, which confirmed the replacement of the iodine by ethynylferrocene. The surface coverage obtained from CV for BuFc, (6.25×10-¹¹ mol cm-²), was higher than for TpFc surfaces, (7.2×10-1¹² mol cm-²). This is could be due to a lower overall reaction yield being associated with each reaction in the two-step process. In order to investigate the utility of ferrocene modified silicon surfaces in applications such as charge storage and memory devices, the EFc surface was studied using electrochemical scanning tunnelling spectroscopy which showed enhanced tunnelling current response that is directly related to the presence of the redox active ferrocene unit. The rate of electron transfer from ferrocenyl-monolayers to n-Si(111) was measured for both pure and mixed monolayers using light step photoelectrochemical chronoamperometry (PC). The rate constant associated with ferrocene oxidation is weakly dependent on applied potential, and is independent of the type of linkage, and the length of the n-alkyl chains in the mixed monolayers. The photoelectrochemical experiment provides a simple means to detect the extent to which the monolayer discharges in the dark and therefore can be used to assess the feasibility of charge storage in these monolayers.
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Viswanathan, Kalpana. "Synthesis and Characterization of Novel Polymers for Functional and Stimuli Responsive Silicon Surfaces." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27052.
Full textAbstract:
The synthesis of a variety of novel functionalized polymers using living polymerization techniques to achieve functional and stimuli responsive coatings on silica surfaces are described. Since microscopic features on a surface influence the overall wetting properties of the surface, a systematic investigation of the influence of polymer architecture on the microscopic characteristics of the modified surfaces was studied using silane-functionalized linear and novel star-branched polystyrene (PS). Star-branched modifiers provide functional and relatively well-defined model systems for probing surface properties compared to ill-defined highly branched systems and synthetically challenging dendrimers. Using these simple star-shaped macromolecules it was shown that the topographies of the polymer-modified surfaces were indeed influenced by the polymer architecture. A model explaining the observed surface features was proposed.
A living polymerization strategy was also used to synthesize centrally functionalized amphiphilic triblock copolymers. The amphiphilic copolymers exhibited stimuli responsive changes in surface hydrophobicity. In spite of multiple solvent exposures, the copolymer films remained stable on the surface indicating that the observed changes in surface properties were due to selective solvent induced reversible rearrangement of the copolymer blocks. The chemical composition of the copolymers was tailored in order to tune the response time of the surface anchored polymer chains. Thus, the polymer coatings were used to reversibly change the surface polarities in an on-demand fashion and could find possible applications as smart adhesives, sensors and reusable membrane devices.
In contrast to the afore-mentioned covalent modification approach, which often leads to permanent modification of surfaces, renewable surfaces exhibiting â universalâ adhesion properties were also obtained through non-covalent modification. By employing hydrogen bonding interactions between DNA bases, surfaces functionalized with adenine groups were found to reversibly associate with thymine-functionalized polymers. This study describing the solvato-reversible polymer coating was the first demonstration on silica surfaces. A systematic investigation of the influence of surface concentration of the multiple hydrogen bonding groups and their structure on the extent of polymer recognition by the modified surfaces is also discussed.Ph. D.
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Prayongpan, Pornpimol. "Adsorption and reaction of amines on silicon and germanium surfaces/." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164538.
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Voelkmann, Carsten. "Five wave mixing investigation of electron dynamics at silicon surfaces." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=96279175X.
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Sharp, Peter. "Passivated silicon and diamond surfaces : mapping, modification and molecular adsorption." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604336.
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The contrasting surface chemistry of passivated and unpassivated Group IV elemental semiconductor surfaces fund amentally affects both their electronic properties and the binding of adsorbates. Partially passivated surfaces offer a way to explore these different environments simultaneously. Control of the surface properties by selective passivation also allows a route to direct the adsorption of atoms and molecules. Herein, we investigate and attempt to manipulate the properties of hydrogen-passivated silicon and diamond surfaces, and subsequently study their interaction with fullerenes. Hydrogen-passivated silicon surfaces have been studied extensively over the past few decades and it is possible to control the passivation of individual silicon atoms via STM hydrogen lithography. Despite this, hardly any work has been done using AFM and there have been no reports of for ce-meditated lithography. We have studied the H:Si(100)(2 x 1) surface with both STM and frequency modulated dynamic AFM. AFM images exhibit both conventional and inverted contrast imaging modes, which we explain in terms of the termination of the probe apex by comparing force spectra to DFT calculations. We also demonstrate hydrogen lithography via voltage pulsing using a Plus sensor.
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Ma, Yuan-Ron. "Adsorption and manipulation of Câ†6â†0 on silicon surfaces." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262962.
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Norga, Gerd Johan Maria. "Chemistry and physics of metallic contaminants on crystalline silicon surfaces." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10904.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996.Includes bibliographical references (leaves 202-210).
by Gerd Johan Maria Norga.
Sc.D.
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Barritt, Elizabeth. "The silver, copper and silicon (110) surfaces in ambient environments." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/12795/.
Full textAbstract:
The results presented in this thesis were part of a research programme that utilised the surface sensitive technique reflection anisotropy spectroscopy (RAS) to study the silver, copper and silicon (110) surfaces under ambient conditions. It has been shown that although the preparation of these surfaces can be less precise in ambient conditions, than when prepared in an ultra high vacuum (UHV) environment, the main features observed are similar. The features observed in the RA spectrum for the Si(110) surface in ambient conditions show good agreement with previous data performed in a UHV environment. The experiments performed using the Ag(110) surface show that when the Ag(110) crystal is heated to higher temperatures, when the oxide present will have dissociated off the surface, the ambient RA spectrum shows good agreement with experiments performed in UHV. However, the transition between surface states observed in UHV was not seen in the RA spectrum in ambient conditions. These experiments were performed using the Re(∆r/r) part of the RA spectra. However, to examine the surfaces further the Im(∆r/r) part of the RA spectra was also presented along with the azimuthal dependence of the RA spectrum. The Cu(110) surface was investigated under ambient conditions and electrochemically. It was found the surface is not stable in ambient conditions but can be stabilised electrochemically using HCl. The adsorption and desorption of Cl- was studied and the research focused on when the Cl- was desorbed from the surface leaving clean Cu(110). Under these conditions the transition between surface states at 2.10 eV in UHV was observed at a slightly higher energy of 2.20 eV in an electrochemical environment.
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Nielsen, Jon-Fredrik. "Energetically and kinetically driven step formation and evolution on Silicon surfaces /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486402957194989.
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Armstrong, Jeffrey Lee. "Reaction of carbonyl-and nitrogen-containing molecules on Si(100) and fluxless solder re-flow on polycrystalline Cu surfaces /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Song, Feng. "Water Droplet Movements on Methyl-terminated Organosilane Modified Silicon Wafer Surfaces." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1208379295.
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Chamberlain, Jeffrey P. "The adsorption of carbon monoxide on silicon and gallium arsenide surfaces." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/29799.
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Zhu, Qunzhi. "Modeling and Measurements of the Bidirectional Reflectance of Microrough Silicon Surfaces." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5062.
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Bidirectional reflectance is a fundamental radiative property of rough surfaces. Knowledge of the bidirectional reflectance is crucial to the emissivity modeling and heat transfer analysis. This thesis concentrates on the modeling and measurements of the bidirectional reflectance for microrough silicon surfaces and on the validity of a hybrid method in the modeling of the bidirectional reflectance for thin-film coated rough surfaces.
The surface topography and the bidirectional reflectance distribution function (BRDF) of the rough side of several silicon wafers have been extensively characterized using an atomic force microscope and a laser scatterometer, respectively. The slope distribution calculated from the surface topographic data deviates from the Gaussian distribution. Both nearly isotropic and strongly anisotropic features are observed in the two-dimensional (2-D) slope distributions and in the measured BRDF for more than one sample. The 2-D slope distribution is used in a geometric-optics based model to predict the BRDF, which agrees reasonably well with the measured values. The side peaks in the slope distribution and the subsidiary peaks in the BRDF for two anisotropic samples are attributed to the formation of {311} planes during chemical etching. The correlation between the 2-D slope distribution and the BRDF has been developed.
A boundary integral method is applied to simulate the bidirectional reflectance of thin-film coatings on rough substrates. The roughness of the substrate is one dimensional for simplification. The result is compared to that from a hybrid method which uses the geometric optics approximation to model the roughness effect and the thin-film optics to consider the interference due to the coating. The effects of the film thickness and the substrate roughness on the validity of the hybrid method have been investigated. The validity regime of the hybrid method is established for silicon dioxide films on silicon substrates in the visible wavelength range.
The proposed method to characterize the microfacet orientation and to predict the BRDF may be applied to other anisotropic or non-Gaussian rough surfaces. The measured BRDF may be used to model the apparent emissivity of silicon wafers to improve the temperature measurement accuracy in semiconductor manufacturing processes. The developed validity regime for the hybrid method can be beneficial to future research related to the modeling for thin-film coated rough surfaces.
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Maraghechi, Pouya, and University of Lethbridge Faculty of Arts and Science. "Dissociation of molecules on silicon surfaces studied by scanning tunneling microscopy." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/634.
Full textAbstract:
Dissociation of trichloroethylene (TCE) molecules on the Si(111)-7x7 and the Si(100)-2x1 surfaces was studied using STM. Though molecular adsorption may also be observed on the Si(111)-7x7 surface, dissociation is the dominant process. From the STM images acquired, products of dissociation were identified, namely chlorine atoms and dichlorovinyl groups. Dissociation of chlorine from the TCE molecule was confirmed by studying not just appearance in STM images but also from studies of tip-induced diffusion. Different binding configurations were proposed for the vinyl group on the Si (111)-7x7 and the Si(100)-2x1 surfaces. Site preference for each product of dissociation is reported on the Si(111)-7x7 surface. Dissociation of molecules such as ammonia, dimethylamine and methyl chloride on the Si(111)-7x7 and Si(100)-2x1 surfaces is reviewed. The field emission process is explained in detail. The usefulness of making field emission measurements is in evaluating the sharpness of STM tips.xviii, 175 leaves : ill. (some col.) ; 29 cm
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Keshavarzi, Shervin [Verfasser], Holger [Akademischer Betreuer] Reinecke, and Ulrich [Akademischer Betreuer] Mescheder. "Silicon needle-like surfaces for room temperature si-si bonding applications." Freiburg : Universität, 2019. http://d-nb.info/1202010865/34.
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Burkinshaw, Michael Stephen. "The lubrication of aluminium-silicon surfaces with a novel antiwear additive." Thesis, University of Leeds, 2010. http://etheses.whiterose.ac.uk/21110/.
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Even though research into aluminium-silicon alloys is becoming increasingly fashionable, very little is known regarding the tribochemistry of these substrates when lubricated with conventional engine oil additives, especially when compared against ferrous surfaces. In this thesis, many advancements and thus contributions have been made in the field of aluminium-silicon lubrication. Firstly, using a Cameron Plint TE77 tribometer, the tribological performance of overbased calcium sulfonate, zinc dialkyldithiophosphate and an organic antiwear additive on aluminium-silicon surfaces were evaluated. Secondly, contact conditions on silicon grains within the AI-Si alloy were replicated using a silicon crystal substrate, as the silicon regions were vital in the effective lubrication of the aluminium-silicon alloy. Simulation was validated through tribological testing. Thirdly, the role of the aluminium matrix under boundary lubricated wear was evaluated using a replicate aluminium alloy. Tribofilm formation and morphology on the three substrates was analysed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Tribofilms were generated on silicon surfaces more effectively than on the aluminium alloy. Wear levels were lower on the non-conductive substrate compared to the aluminium substrate. The mechanical properties of tribofilms on silicon crystal surfaces were analysed using AFM and nanoindentation, and related to observed wear levels. Fourier transform infrared (FTIR) and secondary ion mass spectrometry (SIMS) determined the tribochemistry of generated tribofilms on all three tribosystems to be very similar to those on ferrous substrates. The addition of the organic antiwear additive to lubricants containing detergent, ZOOP or a combination of the two, consistently improved film formation and wear levels in the three tribosystems. The mechanisms by which this occurred were identified using labelling techniques. This research has provided great insight into the effective lubrication of aluminium-silicon substrates, with the results compiled to provide a definitive mechanism by which the boundary lubrication of aluminium-silicon alloys occurs.
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Iyer, Nandini 1974. "Material transfer associated with the contact between polymer and silicon surfaces." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/51564.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (leaves 126-129).
Material transfer due to the contact of surfaces is encountered in a wide variety of engineering applications. One of these is the backside contamination of silicon wafers due to contact with polymer vacuum chucks during spin coating. The present research investigates material transfer associated with this contact. The contact between the silicon wafer and the vacuum chuck was idealized as pin-on-flat interaction and an experimental apparatus was fabricated based on this model. Material transfer from a variety of solid polymers (UHMWPE, Teflon, KEL-F, PMMA, PEEK, and Nylon 66) was studied and characterized by Scanning Electron Microscopy, Atomic Force Microscopy, Optical Microscopy and computer image analysis. This was augmented with studies of material transfer from polymeric films (Polyethylene, Teflon, and Kapton) and ceramics (quartz, sapphire and ruby). The variables of interest for the material transfer phenomenon were identified using analysis of elastic contacts (Hertzian) and adhesion. Experimental results suggest that the material transfer was affected by the contact area that forms between the polymer and the silicon substrate and by the contact pressure at the surface asperities. At low loads, contact area and pressure decreases causing less transfer. There is a linear relationship between the total particle area and the Hertzian contact area. For elastic contacts, the effect of surface roughness is not pronounced. Friction and surface energy also appear to be weak variables in the material transfer phenomenon. The Young's moduli of the polymers also affect material transfer. The number of particles transferred and the total particle area decreased with an increase in Young's modulus. No material transfer was observed with Kapton, quartz, sapphire and ruby. Material transfer was also inhibited with the use of a small amount of lubricant.
by Nandini Iyer.
S.M.
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Nielsen, Jon F. "Energetically and Kinetically Driven Step Formation and Evolution on Silicon Surfaces." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu998579834.
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