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1
Hadley, M. J. "Scanning tunnelling microscopy of Si(111), Pb-Si(111) and Si(113)." Thesis, University of York, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316178.
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Pettus, Kharissia A. "Abstraction on Si (111)-7x7 and Al(111) /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9974118.
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Nazir, Z. H. "Surface magnetism of Fe/Si(111) and Fe/Si(100)." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362272.
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Gregoratti, Luca. "Scanning photoemission microscopy of the silicide phases formed in Ni/Si(111) and Ni+Au/Si(111) systems." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401781.
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Mikhail, Hanna Degani. "Análise teórica da superfície Si(111)-(7x7)." Universidade Federal de Uberlândia, 2007. https://repositorio.ufu.br/handle/123456789/15681.
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In this work, wecarry out theoretical study of the silicon surface reconstruction (7x7)
grown in the [111] direction, denoted by Si(111) (7x7), using the Density Functional
Theory formalism, within the Local Density Approximation (LDA) for the exchange
correlation term. The interaction with the valence electrons and the core ion (nucleus
more core electrons) was described by norm conserving, non local pseudopotential
approach, compatible with the LDA. The one electron Kohn Sham equations was
solved self consistently, by expanding the one electron functions in terms of linear
combination of numerical atomic orbitals. All the calculations were realized using the
Siesta computational code.
Using the clean surface reconstruction model of Si(111) (7x7), propose by Takayanagi
et al.[1, 2], we modeled the surface as a slab, in which the (7x7) unitary cell
contained 200 Si atoms distributed in one adatom layer (Si atoms on the topmost layer)
and the other four layers, with 49 H atoms used for saturate the dangling bonds of the
most internal layer of the slab. The structural analysis of the Si(111) (7x7) reconstructed
surface and the electronic structure analysis showed a good agreement with both the
experimental and theoretical results disposable, reproducing correctly the band structure,
the surface levels and the metallic character of this surface. The obtained energy
per surface atom was 1,132 eV with respect to the bulk energy. It was performed the
study of the vacancy energy formation of adatoms on this surface. We find an average
value of 1,2 eV of a single vacancy formation of adatom the Si(111) (7x7) surface. The
analysis of the energy bands made possible to identify the electronic states due to the
adatoms dangling bonds.
As a first application of the obtained results to the Si(111) (7x7) clean surface, we
investigated the possible states of the physisorption of the chlorobenzene molecules
on specific sites on the Si(111) (7x7) surface. This study showed that chlorobenzene
molecules interact with the surface for distances around 3,0 Å from the adatoms. We
also inferred that the triangular faulted subunit sites are energetically most favorable
to the adsorption than the correspondent triangular unfaulted subunit sites.
We plotted the adsorption energy curve of the chlorobenzene on the corner adatom
at the triangular faulted unitary cell (7x7). The equilibrium distance and the adsorption
energy obtained was 3,005 Å and 0,161 eV, respectively. The magnitude of this
interaction corresponds to a physics adsorption of the chlorobenzene molecule on the
Si(111) (7x7) surface.Neste trabalho, realizamos o estudo teórico da reconstrução (7x7) da superfície de Silício crescida na direção [111], denotada por Si(111) (7x7), utilizando para isto o formalismo da Teoria do Funcional da Densidade, com a Aproximação da Densidade Local (LDA - LocalDensityApproximation) para o termo de troca correlação. A interação entre os elétrons de valência e o íon de caroço (núcleo mais os elétrons de caroço) foi descrita por meio da Teoria dos Pseudopotenciais não locais de norma conservada, compativel com a LDA. As equações de Kohn Sham de um elétron foram resolvidas autoconsistentemente, expandindo as funções de um elétronemtermos de combinação linear de orbitais atômico numéricos, com base double . Todos os cálculos foram realizados utilizando o código computacional Siesta. Utilizando o modelo de reconstrução da superfície livre de Si(111) (7x7), proposto por Takayanagi et al.[1, 2], modelamos a superfície como um slab, cuja célula unitária (7x7) contém 200 átomos de Si distribuidos em uma camada de adatoms (átomos de Si adsorvidos sobre a superfície propriamente dita) e quatro outras camadas, além dos 49 átomos de H usados para saturar as ligações pendentes da camada mais interna ao material. A análise estrutural da superfície reconstruída Si(111) (7x7) e a análise da estrutura eletrônica mostrou ótima concordância tanto com trabalhos experimentais quanto teóricos, reproduzindo corretamente a estrutura de bandas, os níveis de superfície e o caráter metálico desta superfície. A energia obtida em nosso cálculo por átomo da superfície, com relação à energia bulk, foi de 1,132 eV. Foi feito o estudo da energia de formação de vacâncias do tipo adatom. Encontramos um valor médio de 1,2 eV para a formação de uma única vacância do tipo adatom na superfície Si(111) (7x7). A análise da estrutura de bandas do sistema com vacância possibilitou identificar os estados eletrônicos devido às ligações pendentes dos adatoms. Como uma primeira aplicação dos resultados obtidos para a superfície livre de Si(111) (7x7), investigamos possíveis estados de fisiossorção de moléculas de clorobenzeno sobre sítios específicos sobre a superfície de Si(111) (7x7). Este estudo mostrou que as moléculas de clorobenzeno interagem com a superfície para distâncias de aproximadamente 3,0 Å dos adatoms. Também inferimos que sítios da subunidade triangular faulted são mais favoráveis à adsorção do que sítios correspondentes sobre a subunidade triangula unfaulted. Levantamos a curva da energia de adsorção do clorobenzeno sobre o adatom de canto da subunidade triangular faulted da célula unitária (7x7). A distância de equilíbrio e a energia de adsorção obtidas foram 3,005 Å e 0,161 eV, respectivamente. A ordem de grandeza desta interação corresponde a uma adsorção física da molécula de clorobenzeno sobre a superfície Si(111) (7x7).
Mestre em Física
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Mathieu, Gilles. "Étude des interfaces métal noble-semiconducteur : cu/si(111) et au/si(111) par différentes techniques d'analyse de surface." Aix-Marseille 2, 1987. http://www.theses.fr/1987AIX22072.
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Etude experimentale par spectrometrie auger, diffraction d'electrons lents, spectrometrie de pertes d'energie d'electrons, photoemission directe et microscopie electronique en transmission. Analyse des proprietes electroniques pour le systeme cu/si dans le cas d'une monocouche deposee a chaud et a temperature ambiante. Etude de la microstructure de l'interface au/si (111) constituee par une matrice amorphe au/si contenant des microcristallites d'or pur. Caracterisation par microscopie par effet tunnel du systeme au/si (111)
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Wetzel, Patrick. "Etude de l'interface Cr/Si (111) par photoémission angulaire et diffraction d'électrons lents : épitaxie des siliciures Cr Si et Cr Si2 sur Si (111)." Mulhouse, 1988. http://www.theses.fr/1988MULH0077.
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Etude de la structure électronique et cristallographique de l'interface métal-semiconducteur Cr/Si (111). Deux paramètres gouvernent essentiellement cette structure : le recouvrement de Cr et la température de recuit. Un processus de réaction à l'interface et de diffusion des atomes Si à travers le film métallique est mis en évidence à température ambiante. L'interface formée à haute température (350°C < T < 450°C) est caractérisée par la croissance de siliciures (CrSi, CrSi2) polycristallins, pour des recouvrements supérieurs à 30 monocouches de Cr et de siliciures monocristallins épitaxiques pour des recouvrements inférieurs
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Spence, David John. "STM and MEIS studies of the Ag/Ge(111) and Pb/Si(111) systems." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286036.
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Reis, Roberto Moreno Souza dos. "Síntese de SiC por implantação iônica de carbono em SIMOX(111) e Si(111)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16135.
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SiC é um semicondutor promissor para dispositivos eletrônicos de alta-potência, alta-freqüência e alta temperatura e a síntese de uma camada epitaxial de SiC por implantação, na superfície do Si, pode ser uma via de integração com a tecnologia de Si. Implantação em alta temperatura (600°C) através de uma capa de SiO2, recozimento pós-implantação a 1250°C sob um ambiente de Ar (com 1% de O2) e ataque químico são a base da presente síntese. Implantações à energia de 40 keV foram executadas em substratos SIMOX(111) e Si(111), cobertos com uma capa de 100 nm de SiO2. Implantação em SIMOX foi o foco principal. Isto nos permitiu obter uma camada sintetizada de SiC separada do Si bulk e analisar as conseqüências estruturais. Neste caso, foi produzida a conversão da camada superior de 65 nm de Si superior da estrutura SIMOX em 30-45 nm de SiC. Implantações seqüenciais de C (passos de fluências de ~ 5 × 1016 C/cm2), seguidas por recozimento à 1250°C, permitiu estimar as fluências mínimas de C para atingir a estequiometria como 2,3 × 1017 C/cm2 e 2,8 × 1017 C/cm2, quando implantado em SIMOX e em Si, respectivamente. Espectrometria de Retroespalhamento de Rutherford (RBS) foi empregada para medir a evolução composicional da camada. Pela análise das implantações seqüenciais, foi possível compreender a redistribuição de carbono durante a implantação e recozimento. Uma estrutura de duas camadas é observada no SiC sintetizado separado do Si bulk, sendo a camada superficial mais rica em Si. Microscopia Eletrônica de Transmissão (TEM) mostrou que as camadas sintetizadas são sempre cúbicas e epitaxiais à estrutura original do Si. TEM também mostrou que as implantações diretas, até as fluências mínimas, resultam em uma melhor qualidade estrutural. Para uma fluência muito mais alta (4 × 1017 C/cm2), uma camada completamente estequiométrica é obtida, com redução na qualidade estrutural. Nossos resultados indicam que o excesso de carbono é o principal fator determinante da qualidade cristalina final do SiC sintetizado por feixe de íons, quando comparado ao stress, resultante de um casamento de redes forçado entre o substrato Si e o SiC sintetizado.SiC is a promising semiconductor for high-power, high-frequency and hightemperature electronic devices and the synthesis of an epitaxial layer of SiC by implantation, on the surface of Si, can be a route for integration with the Si technology. High temperature implantation (600oC) through a SiO2 cap, 1250oC post-implantation annealing under Ar ambient (with 1% of O2), and chemical etching are the base for the present synthesis. 40 keV carbon implantations were performed into SIMOX(111) and Si(111) substrates covered with a 100 nm SiO2 cap. Implantation into SIMOX was the main focus. It has allowed us to obtain a SiC synthesized layer separated from the bulk silicon and to analyze the structural consequences. In this case, it was performed the conversion of a 65 nm Si(111) overlayer of a SIMOX(111) into 30-45 nm SiC. Sequential C implantations (fluence steps of about 5 × 1016 C/cm2), followed by 1250oC annealing, has allowed to estimate the minimum C fluences to reach the stoichiometric composition as 2.3 × 1017 C/cm2 and 2.8 × 1017 C/cm2, when implanting into SIMOX and into Si, respectively. Rutherford Backscattering Spectrometry (RBS) was employed to measure layer composition evolution. By analyzing the sequential implantations it was possible to understand the carbon redistribution during implantation and annealing. A two-sublayers structure is observed in the synthesized SiC separated from the bulk Si, being the superficial one richer in Si. Transmission Electron Microscopy (TEM) has shown that the synthesized layers are always cubic and epitaxial to the original Si structure. TEM also show that single-step implantations, up to the minimum fluences, result in better structural quality. For a much higher C fluence (4 × 1017 C/cm2), a whole stoichiometric layer is obtained, with reduction of structural quality. Our results indicate that excess of carbon content is the major detrimental factor to determine the final crystalline quality in SiC ion beam synthesis, as compared to the stress, resulting from a forced lattice matching between the Si substrate and the synthesized SiC.
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Anderson, Sarah. "Second-harmonic generation as a probe of chemically modified Si(111) surfaces and the initial oxidation of hydrogen terminated Si(111)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59270.pdf.
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AMOKRANE, AMAL. "Etude des proprietes electroniques et structurales des interfaces gase/si(111) et inse/si(111) par la photoemission angulaire dans l'ultraviolet." Paris 6, 1998. http://www.theses.fr/1998PA066010.
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Cette these concerne l'etude des proprietes electroniques et structurales aux interfaces d'heterostructures formees par depot epitaxial du semiconducteur lamellaire gase ou inse sur un substrat si(111)11-h. L'interface est atteinte par desorption thermique progressive sous ultravide des couches de lamellaire deposees. Les techniques employees sont la photoemission angulaire dans l'ultraviolet utilisant le rayonnement synchrotron et la diffraction d'electrons lents. L'etude des couches epitaxiees de gase et d'inse, de 5 a 30 nm d'epaisseur, avant leur desorption thermique, montre que celles-ci ont des proprietes electroniques essentiellement similaires a celles des materiaux massifs. La structure de bande experimentale des couches minces d'inse est trouvee semblable a celle calculee pour le polytype gamma du materiau massif. L'etude des heterostructures gase/si(111) et inse/si(111) au cours de leur erosion thermique montre que le traitement thermique provoque une rugosification importante de la surface. Pour le systeme gase/si(111), la decomposition des spectres de niveaux de coeur ga-3d et se-3d montre que : (i) a l'interface un transfert de charge se produit des liaisons ga-se du demi-feuillet contraint lie au substrat vers les atomes de si ; (ii) la contribution de feuillets gase contraints de meme parametre de maille que si, apparaissant avant que l'interface ne soit atteinte, fait intervenir un transfert de charge des atomes de ga vers les atomes de se. Pour le systeme inse/si(111), nous avons trouve que les liaisons in-in et in-se des feuillets inse contraints au parametre de maille de si, et les liaisons in-se a l'interface sont construites a partir d'etats plus profonds que dans le compose lamellaire inse. Lorsque le traitement thermique induit a l'interface une reconstruction si(111)55 specifique d'inse, les spectres de niveaux de coeur in-4d et se-3d montrent que les atomes d'in et de se ont plusieurs environnements chimiques.
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Layet, Jean-Marc. "Contribution à l'étude des excitations électroniques de surfaces et d'interfaces sur les systèmes Si(111)-7x7 et Ag/Si(111)-7x7." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375990425.
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Ladeveze, Marielle. "Le système Sb-Si sur Si(111) fortement désorienté : croissance, intéraction et dopage." Aix-Marseille 2, 1996. http://www.theses.fr/1996AIX22065.
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Cette etude met en evidence plusieurs aspects, jusqu'a nos jours non explores, de l'influence de la desorientation du substrat sur l'epitaxie par jets moleculaires silicium. L'orientation utilisee correspond a une surface de silicium (111) desorientee de 10 autour de la direction 1-10 vers la direction -1-12. Nous montrons d'abord comment une telle surface evolue pendant la croissance de silicium. Nous analysons ensuite l'interaction de l'antimoine (dopant du silicium) avec cette surface. Enfin, nous etudions le dopage de silicium par l'antimoine lors d'un codepot silicium-antimoine. La surface de silicium, initialement organisee suivant un arrangement regulier de marches de hauteur triatomique, devient rugueuse pendant la croissance. Cette rugosite peut s'expliquer par une frequence de vibration plus elevee pour les adatomes descendant les marches. Grace a des experiences de thermodesorption, menees par spectroscopie d'electrons auger et par spectrometrie de masse, couplees a des calculs de dynamique moleculaire, nous mettons en evidence des etats d'adsorption de l'antimoine differents sur les marches et sur les terrasses. Enfin, nous montrons que la presence de l'antimoine pendant la croissance modifie la morphologie de la surface desorientee. Quant au dopage, la difference d'incorporation entre une surface nominale et une surface desorientee que nous observons peut s'interpreter par la prise en compte simultanee des comportements de segregation et de desorption de l'antimoine a la surface de silicium en presence de marches
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Bonet, Christopher. "Study of rare earth metals on Si (111) and Ge (111) using LEED and KED." Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399784.
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Gorgoi, Mihaela. "Electronic Properties of Phthalocyanines Deposited on H-Si(111)." Doctoral thesis, Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200700213.
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Im Rahmen dieser Arbeit wurden vier Phthalocyanine untersucht: Metallfreies-Phthalocyanin (H2Pc), Kupferphthalocyanin (CuPc) und Fluor-substituiertes Phthalocyanin (F4CuPc und F16CuPc). Das Ziel dieser Arbeit ist die Charakterisierung der elektronischen und chemischen Eigenschaften der Grenzflächen zwischen diesen Molekülen und Silizium. Die Moleküle wurden durch organische Molekularstrahldeposition (OMBD) im Ultrahochvakuum auf wasserstoffpassivierte Si(111)-Substrate aufgedampft. Oberflächensensitive Messmethoden wie Photoemissionsspektroskopie (PES), Bremsstrahlung Isochromaten Spektroskopie (BIS oder IPES - Inverse Photoemissionsspektroskopie) und Spektroskopie der Röntgen-Absorptions-Feinstruktur (NEXAFS – Near Edge X-Ray Absorption Fine Structure) wurden zur Charakterisierung eingesetzt. Um eine Zuordnung der verschiedenen Komponenten in PES und IPES zu ermöglichen, wurden Methoden der Dichtefunktionaltheorie zur theoretischen Berechnung eingesetzt. Die Energieniveauanpassung an der Grenzfläche zwischen der organischen Schicht und der H-Si-Grenzfläche, sowie die Transportbandlücke von H2Pc, CuPc, F4CuPc und F16CuPc wurden mit Hilfe von PES und IPES bestimmt. Die NEXAFS-Messungen ermöglichten eine genaue Bestimmung der Molekülorientierung relativ zum Substrat. Die Auswertung der Daten zeigte unterschiedliche Molekülorientierungen in dünnen und dicken Filmen. Diese Änderungen wurden mit dem bandverbiegungsähnlichen Verlauf der HOMO-und LUMO-Positionen in Verbindung gebracht. Zusätzlich zu diesem Verhalten wiesen die Grenzflächen auch einen Grenzflächendipol auf, welcher durch die unterschiedlichen Austrittsarbeiten der Kontaktmaterialien hervorgerufen wird. Der Einfluss des Grads der Flouridierung wird durch eine ähnlichen Zunahme der Elektronenaffinität (EA), der Austrittsarbeit (WF) und der Ionisierungsenergie (IE) bestätigt. Die elektronischen Eigenschaften von Metall/organische-Schicht-Grenzflächen und von organischen Schichten unter Sauerstoffeinfluss wurden mit Hilfe von PES und IPES untersucht. Die Ag/Pc Grenzflächen zeigten eine Mischung aus HOMO-LUMO-Verschiebungen und Grenzflächendipolbildung. An den Ag/H2Pc- und Ag/F16CuPc- Grenzflächen wurde ein Ladungstransferkomplex gebildet. Auf der CuPc-Schicht physisorbiert das Ag lediglich und im Fall von F4CuPc wird Ladung zu Ag transferiert, wobei eine andauernde n-Typ-Dotierung an der Grenzfläche erzeugt wird. In Analogie zum Fall der Pc/H-Si Grenzfläche wiesen die Dipole, die hier gefunden wurden, eine lineare Abhängigkeit von EA, WF und IE auf und können durch die Differenz zwischen den Austrittsarbeiten vorausgesagt werden. Das Verhalten der dicken organischen Schichten unter Sauerstoffeinfluss kann in zwei Gruppen eingeteilt werden. Eine Gruppe, bestehend aus H2Pc und F4CuPc, wies nur schwache Wechselwirkung auf und der Sauerstoff physisorbiert auf der Pc-Schicht. Die beiden anderen Moleküle, CuPc und F16CuPc konnten einer Gruppe starker Wechselwirkung zugeordnet werden. CuPc bildet einen Ladungstransferkomplex mit Sauerstoff und auf F16CuPc wird eine polarisierte Schicht gebildetIn the context of this work four Phthalocyanine were studied: Metal-free Phthalocyanine (H2Pc), Copper Phthalocyanine (CuPc) and fluorine-substituted Phthalocyanine (F4CuPc and F16CuPc). The goal of this work is the electronic and chemical characteristics of the interfaces. The molecules were deposited by organic molecular beam deposition (OMBD) in the ultra high vacuum on hydrogen-passivated Si(111)-Substrate. Surface sensitive techniques such as photoemission spectroscopy (PES), bremsstrahlung isochromate spectroscopy (BIS or IPES - inverse photoemission spectroscopy) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) were used for characterisation. Theoretical computations by density functional theory methods were employed, in order to assign different components in PES and IPES. The energy level alignment at the organic/H-Si interface, as well as the transport gap of H2Pc, CuPc, F4CuPc and F16CuPc were determined by PES and IPES. The NEXAFS measurements determine the exact molecular orientation with respect to the substrate. The evaluation of the data showed different molecular orientation in the thin and thick films. This change was correlated with the band bending like behaviours that emerged at these interfaces. In addition to the band bending like behaviour, the interfaces show also an interface dipole which is driven by the work function difference between the contact materials. The influence of the degree of fluorination is confirmed in the similar increase of the EA, WF and IE. The electronic properties of metal/organic layer interfaces and of organic layer under oxygen influence were examined by PES and IPES. The Ag/Pc interfaces show a mixture of HOMO-LUMO shifts and interface dipole formation. A charge transfer complex is formed in the case of Ag/H2Pc and Ag/F16CuPc interfaces. Ag is physisorbed atop the CuPc. Charge transfers from F4CuPc to Ag creating a continuous n-type doping at the interface. Similar to the Pc/H-Si interfaces the interface dipoles found here show a linear dependence on the EA, WF and IE and can be predicted by the difference in the work functions. The data evaluation of oxygen exposed thick films determined two groups of behaviours. The weak interaction group is represented by H2Pc and F4CuPc, Pcs on which oxygen is physisorbed. The strong interaction group contains the other two molecules CuPc and F16CuPc. CuPc forms a charge transfer complex with oxygen and on top of F16CuPc a polarized layer is formed
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Laferrière, Marie. "Cinétique de la photodéposition d'alcènes sur le SI(111)." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6344.
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La surface du Si(111) est hydrogénée en utilisant une variante de la méthode RCA, suivi d'une immersion dans le NH 4 F 40%. Cette surface hydrogénée est caractérisée par spectroscopie infrarouge dans un arrangement géométrique de multiples réflexions internes. Le pic de réflectance des Si-H est mince et intense ce qui indique que la surface hydrogénée est homogène et atomiquement plate. En présence de 1-octène et de 1-hexadécène, une monocouche alkyle est formée par exposition à une radiation UV. Ces monocouches alkyles ont été caractérisées par spectroscopie infrarouge. L'intensité relative des bandes de réflectance des étirements symétriques et asymétriques des méthylènes est comparable aux valeurs publiées pour des chaînes de dimensions comparables. Les mesures d'absorbance dans la polarité s et p permettent de déterminer un angle d'inclinaison pour le 1-hexadécène adsorbé par rapport à la normale qui varie de 18° à 45°. La photodéposition de 1-hexadécène a été suivie par spectroscopie in-situ. Ces spectres présentent des bandes unipolaires et bipolaires. Une étude cinétique des spectres qui présentent des bandes unipolaires est faite pour déterminer un mécanisme d'adsorption. Les résultats suggèrent un processus d'adsorption qui serait compatible avec un processus radicalaire en chaîne.
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Kury, Peter. "Verspannungseffekte bei der Epitaxie organischer Halbleiter: Pentazen-Si(111)." Aachen Shaker, 2007. http://d-nb.info/988141477/04.
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Weeks, Ann Elizabeth. "Si(111) atom-optical mirrors for scanning helium microscopy." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611911.
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Metzler, Martin [Verfasser]. "Untersuchungen zur Metallabscheidung auf Si(111)-Elektroden / Martin Metzler." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2015. http://d-nb.info/1069161780/34.
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Srour, Waked. "Propriétés structurales et électroniques de Sn/Ge/Si(111), Sn/Si(111) : B et analogie entre intensités photoémise et diffractée en surfaces superpériodiques." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0209/document.
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Les propriétés physiques des systèmes dépendent fortement de la dimensionnalité. L'exaltation des corrélations électroniques, la séparation spin charge dans le liquide de Luttinger et les ondes de densité de charge en sont des exemples. Les surfaces semiconductrices avec une dimension réduite servent à étudier la corrélation électronique, elles sont favorables à présenter des transitions de Mott avec leurs états de surface peu dispersifs, ainsi que la manière de découpler les états électroniques de nanostructures du substrat dans la recherche de propriétés électroniques singulièresNot available
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Nguyen, Van H. "Epitaxial growth of relaxed Ge buffers on (111) and (110) Si substrates using RP-CVD." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/50222/.
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The continued scaling of Si metal oxide semiconductor field effect transistor (MOSFET) devices to enhance performance is reaching its fundamental limits and the need for new device architecture and/or new materials is driving research and development within the semiconductor industry. Germanium, with its much higher intrinsic carrier mobilities, has a considerable advantage over Si as a channel material and its compatibility with current complementary metal oxide semiconductor (CMOS) technology makes it a very promising candidate. There is currently significant technological interest in the epitaxial growth of high quality relaxed Ge layers directly on Si substrates for potential applications including: high-mobility metal-oxide-semiconductor field-effect-transistors (MOSFETs), infrared photodetectors, solar cells and III-V integration. The crystallographic orientation of the substrate also influences the inversion layer mobility in transistors; compared to (100) orientation, Ge grown on (111) and (110) substrates can considerably enhance the carrier mobilities for electrons and holes. The 4.2% mismatch between Ge and Si is, however, a major drawback for the growth of high quality epitaxial layers, as 3-dimensional islanding, surface roughening and the generation of a high density of defects can occur which are all detrimental to performance of prospective devices. In particular, epitaxial growth on (110) and (111) surfaces is more susceptible to the formation of extended stacking faults as the gliding sequence of the dissociated 30° and 90° partial dislocations is reversed with respect to that for the (100) surface. This means that the concept of a thick graded buffer for gradual strain relaxation is not as easily applicable in the case of (111) and (110) substrates. In this work, we have investigated the growth of relaxed Ge films on (111) and (110) Si substrates by reduced-pressure chemical vapour deposition (RP-CVD) in an ASM Epsilon 2000 reactor using the high temperature/ low temperature growth technique, which comprises of a thin low temperature (LT) Ge seed, a thick high temperature (HT) Ge layer and subsequent in-situ high temperature H2 anneal. We will show how the growth conditions influence both the presence and nature of defects within the Ge layers, their surface morphology and also the state of relaxation using transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. Formation of islands in the 10 nm Ge seed layer has led to a significant enhancement in the quality of the buffer by providing a effective way to relax the layers, reducing the densities of stacking faults and threading dislocations by at least a decade compared to previous studies and also producing a smooth surface around 2 nm rms.
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Destefanis, Vincent. "Dépôt et gravure en phase vapeur d'hétérostructures Si/SiGe sur substrats (100), (110) et (111)." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0079.
Full textAbstract:
Le dépôt CVD de Si/SiGe et leur gravure sélective par HCl ont été étudiés sur substrats Si(100), (110) et (111). L’épitaxie de Si/SiGe a démontré de plus faibles vitesses de croissance du SiGe(110) ainsi que de plus faibles %Ge(110). L’intégration de couches (110) sur des substrats avec motifs a mené à la fabrication de dispositifs SOI Localisé (110) avec de forts gains de mobilités de trous. La croissance de substrats virtuels épais de SiGe a mené à des densités de défauts élevées sur (110) et (111). Les fortes valeurs de contraintes de couches de Si(110) contraintes en tension semblent toutefois prometteuses. L’épitaxie locale de Ge(110) relaxé dans des motifs a mis en évidence des défauts normaux à la surface (110). La gravure sélective HCl du SiGe par rapport au Si, étudiée à hautes pressions, a amélioré les vitesses et sélectivités de gravure sur (100). Ces résultats de gravure obtenus sur (100) contrastent avec les sélectivités de gravure médiocres mises en évidence sur (110)CVD deposition of Si/SiGe on (100), (110) and (111) substrates and their selective chemical vapour etch using HClhave been studied. The epitaxy of Si/SiGe has notably highlighted lower SiGe(110) growth rates and Ge(110) contents than on (100). Integration of (110) epitaxiallayers on patterned Si substrates has led to (110) Localized Silicon On Insulator devices with impressive hole mobility gains. Growth of thick, fully-relaxed SiGe virtual substrates has noticeably shown a high defectivity on (110) and (111). The high levels of strain obtained in (110) tensily strained Si layers seem however promising. The selective epitaxial growth of relaxed Ge(110) layers in narrow patterns has exhibited defects normal to the (110) surface and poor defect trapping. The HCI lateral selective etching of SiGe versus Si at high HCI pressure has improved (100) etch rates and selectivities. These technologically relevant (100) etching results contrast with the poor (110) etching selectivities obtained
23
Hortamani, Mahboubeh. "Theory of adsorption, diffusion and spinpolarization of Mn on Si(001) and Si(111) substrates." [S.l.] : [s.n.], 2006. http://www.diss.fu-berlin.de/2006/588/index.html.
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Kraus, Alexander. "Präparation und Charakterisierung von Nanostrukturen mittels Rastertunnelmikroskopie auf Si(111)." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965442101.
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Schillinger, Richard. "NMR-Experimente zur elektronischen Struktur der Si(111)-(7x7)-Oberfläche." [S.l. : s.n.], 2003. http://archiv.ub.uni-marburg.de/diss/z2003/0777/.
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Juteräng, David. "STM Study of PTCDA on Pb/Si(111) 1×1." Thesis, Karlstads universitet, Fakulteten för teknik- och naturvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-16179.
Full textAbstract:
The interaction and orbital energy levels of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) molecules on a Pb/Si(111) 1x1 substrate have been investigated. A Si(111) sample was annealed to form the 7x7 configuration. 1.5 monolayer of Pb was evaporated onto the surface, which was then annealed. 0.5 monolayer of PTCDA was applied to the substrate through molecular beam epitaxy (MBE). The surface configuration of the substrate was monitored step by step by low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Scanning tunneling spectroscopy (STS) was used to pinpoint the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the molecules. It was found that the PTCDA molecules formed a herringbone pattern on the substrate. The PTCDA electronic energy levels corresponding to the HOMO and the LUMO were obtained. From these values the energy gap between these orbitals, the molecular bandgap of PTCDA on Pb/Si(111) 1x1, was determined.
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Xu, Zhongjie, and 徐忠杰. "Molecular beam epitaxial growth of GaN on Si(111) substrate." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45866338.
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Cherepanov, Vasily. "Influence of material, surface reconstruction and strain on submonolayer growth at Si(111) and Ge(111) surfaces." kostenfrei, 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972087559.
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Ezzehar, Hafid. "Premières étapes de la chimisorption de l'hydrogène atomique sur les surfaces Pd(111) et Si(111) 7x7." Mulhouse, 1995. http://www.theses.fr/1995MULH0410.
Full textAbstract:
Dans ce travail, nous avons considéré les premières étapes de la chimisorption de l'hydrogène sur les surfaces Pd(111) et Si(111) 7x7. Ces deux sujets demandent des approches théoriques très différentes. I) système H/Pd(111) : le système H/Pd(111) a été traité dans un modèle de liaisons fortes utilisant la méthode récursive et les déphasages complexes. Cette méthode permet d'obtenir des expressions self-consistantes pour les densités d'états locales et les énergies d'interaction entre impuretés. Dans ce cadre nous avons étudié le problème de l'impureté isolée d'hydrogène et celui des interactions multiatomiques entre impuretés qui nous ont permis de comprendre la surstructure observée à la surface lors de la chimisorption de l'hydrogène sur Pd(111) et de préciser la nature des sites occupés. II) système H/Si(111) 7x7 : ce système a été étudié dans le modèle DAS (Dimer adatom stacking fault) dans le cadre de l'extension cristalline de la méthode de Hückel étendue. Elle permet une bonne description de la structure électronique de la surface Si(111) 7x7 propre. Dans le cas où 19 liaisons pendantes des atomes de silicium à la surface sont saturées, nous avons reproduit les 2 pics observés en photoémission et proposé une interprétation des résultats expérimentaux. Le calcul des densités d'états et l'analyse des fonctions d'ondes ont permis de souligner le rôle fondamental de l'interaction hydrogène-adatomes dans la formation de ces 2 pics
30
Boutaoui, Noureddine. "Contribution à l'étude de l'adsorption d'un métal sur le silicium par microanalyse Auger : application à l'étude des couples Pd-Si(111) et Ag-Si(111)." Lyon 1, 1990. http://www.theses.fr/1990LYO10126.
Full textAbstract:
Dans ce travail, nous nous sommes attaches a etudier les interfaces pd/si (111) et ag/si (111) par microscopie electronique a balayage et microspectrometrie auger. Nos investigations ont conduit aux resultats suivants: 1) systeme pd/si (111): pour des recouvrements inferieurs a quelques monocouches 5mc, la phase pd#2si croit sur la surface si (111) par couches alternativement riches et pauvres en atomes de silicium, a temperature ambiante. Les traitements thermiques entre 200 et 400#oc provoquent une segregation du silicium sur cette phase; 2) systeme ag/si (111): pour des temperatures superieures a 200#oc, l'argent croit sur le silicium (111) selon le mode stranski-krastanov. L'epaisseur de la couche segregee a ete estimee, a 400#oc, a environ 2/3 mc. En ce qui concerne la migration superficielle de l'argent, nous avons etabli que pour des temperatures comprises entre 400 et 450#oc, la diffusion des adatomes semble s'effectuer sur la couche 2d. Dans le domaine des hautes temperatures (t450#oc), l'extension laterale de la couche (2d) est limitee par la description des adatomes. A plus basse temperature, l'extension de cette couche pourrait etre controlee par l'autodiffusion de surface des atomes d'argent sur les ilots 3d avec une energie d'activation de l'ordre de 2,4 ev/atome
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Hild, Rüdiger. "Sb und Bi als Surfactants auf Si(001) und in der Ge-Heteroepitaxie auf Si(111)." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983681325.
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Rausch, Tim. "High frequency Giant Magnetoresistance in evaporated Co/Cu multilayers deposited on Si(111) and Si(100)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0018/MQ52646.pdf.
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Satti, Didier. "Etude des interfaces Ta/Si (111) et Ta/Si (100) par différentes techniques d'analyse de surface." Aix-Marseille 2, 1989. http://www.theses.fr/1989AIX22043.
Full textAbstract:
Etude des proprietes structurales et electroniques des interfaces ta/si (111) et ta/si (100) elaborees sous ultra-vide. Ces systemes sont caracterises in situ par spectrometrie auger (aes), diffraction d'electrons lents (leed), spectroscopie de pertes d'energie d'electrons (eels), photoemission directe (ups), et ex situ par microscopie electronique a balayage
34
Guirleo, Guillaume. "Etude des propriétés électriques et optiques d'hétérostructures Si/CaF2 déposées sur des substrats de Si(111)." Phd thesis, Aix-Marseille 2, 2002. http://www.theses.fr/2002AIX22059.
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Gerrard, Alex. "Interactions of atomic oxygen with Pt(111) and nitrided Si(100)." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010104.
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Hugelmann, Martin. "Erzeugung und Charakterisierung metallischer Nanostrukturen auf n-Si(111):H-Einkristalloberflächen." Karlsruhe : Univ.-Verl, 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973495839.
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Dusciac, Dorin. "Couches organiques ultra minces greffées sur Si (111) pour la microélectronique." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00004637.
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L'usage des oxydes high-K comme diélectriques de grille dans les transistors MOSFET s'impose comme une étape obligatoire pour maintenir la croissance continue des performances électriques de ces composants électroniques. Malheureusement, le dépôt de ces oxydes sur silicium pose des problèmes sérieux (formation d'une couche intermédiaire de silice ou d'un siliciure métallique, mauvaise maîtrise de la qualité électronique de l'interface, mobilité des porteurs réduite, etc.). Une voie envisageable pour réaliser des interfaces Si/high-K de bonne qualité est l'utilisation d'une couche mince de « primaire » organique. Le greffage de chaînes organiques saturées par pontage Si-O-C (silicium-alcoxyle) a été exploré. La stabilité thermique des couches greffées a été étudiée par spectroscopie infrarouge. Il apparaît que la décomposition ne s'effectue pas par rupture de l'ancrage Si-O-C, mais par fragmentation de la chaîne. Ce processus a été modélisé qualitativement par une simulation numérique. Pour optimiser les couches organiques greffées, les efforts se sont orientés vers le greffage de chaînes fonctionnelles ultra-courtes et à terminaison hydrophile. Cependant, la terminaison fonctionnelle de ces chaînes peut interférer avec la réaction de greffage, soit en inhibant la réactivité de la terminaison à greffer, soit en induisant des réactions parasites. L'hydrolyse d'esters courts greffés, nécessaire pour obtenir des terminaisons hydrophiles, n'a pu être réalisée sans éviter l'hydrolyse de l'ancrage Si-O-C. Le dépôt de couches de HfO2 a été réalisé sur des couches organiques dont le greffage est bien maîtrisé. Les couches s'avèrent continues, bien qu'un peu plus rugueuses que sur substrat de silicium non greffé. L'infrarouge indique une décomposition partielle de la couche organique mais la surface du silicium apparaît largement préservée de l'oxydation. Ces résultats préliminaires semblent indiquer que la stabilité thermique de la couche organique ne constitue pas une barrière infranchissable et que l'approche considérée peut être viable. Mots-clés : couches organiques, oxydes high-K, greffage, spectroscopie infrarouge, stabilité thermique, hydrolyse
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Tanaka, Shigeyasu, Yoshio Honda, and Nobuhiko Sawaki. "Structural characterization of GaN laterally overgrown on a (111)Si substrate." American Institute of Physics, 2001. http://hdl.handle.net/2237/6985.
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Kury, Peter [Verfasser]. "Verspannungseffekte bei der Epitaxie organischer Halbleiter: Pentazen/Si(111) / Peter Kury." Aachen : Shaker, 2008. http://d-nb.info/1162790059/34.
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Dunn, Andrew William. "Adsorption and manipulation of Câ†6â†0 on Si(111)-7x7." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388246.
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Blab, Marcus [Verfasser]. "Ladungstransportmessungen an Si(111)-Oberflächen mit einem Multispitzen-Rastertunnelmikroskop / Marcus Blab." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2015. http://d-nb.info/1074566084/34.
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Bardhan, Abheek. "Integration of AlGaN with (111) Si Substrate by MOCVD." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4298.
Full textAbstract:
AlGaN is an important semiconductor material for electronic and optoelectronic applications.
The change in composition of AlGaN (AlN to GaN) provides a range of bandgaps extending
from 6.01 eV, far ultraviolet, to 3.4 eV. This higher bandgap results in a higher breakdown
voltage, than GaN one of the current materials of choice, in the devices made out of it.
Carrier transport is also less sensitive to temperature variation. Hence, AlGaN with high Al
fraction is a suitable candidate for power transistor technology. For optoelectronic
applications like UV-photodetectors and UV-emitters, the full range of AlGaN provides the
tunability in wavelength ranging from 206 nm (AlN) to 360 nm (GaN). As the solar spectrum
ranges from about 250 nm to 2500 nm, AlGaN with high Al fraction is useful for solar-blind
UV applications. AlGaN UV emitters on the other hand can be used in water purification.
Till date all these developments have been carried out by growing AlGaNs on expensive
substrates like SiC, sapphire or freestanding AlN. But the growth of AlGaN on Si (111)
substrates are desirable as opposed to commonly used substrates such as sapphire, SiC or AlN
owing to its higher thermal conductivity (except SiC), low cost and availability in large area.
Integration with Si opens up the possibility to integrate the multifarious applications of
AlGaN with the economic viability of Si (111) substrates. The present work focuses on the
integration of AlGaN on Si (111) substrates by MOCVD. The bounds placed on the
competing requirements composition, thickness, stress, defect density and surface roughness
due to the physico-chemical aspects of AlGaN growth have been identified. Using such
understanding an AlGaN/AlGaN high electron mobility transistor and a UV detector have
been demonstrated.
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許志榮. "Exchange-bias phase diagram of CoO/Co/Si(111) and magnetic properties of Co/Ag-Si √3×√3/Si(111)." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/14394464097149320427.
Full textAbstract:
碩士國立臺灣師範大學
物理學系
99
In this thesis, we focus on the physical properties of CoO/Co/Si(111) and Co/Ag-Si √3 × √3/Si(111) systems. For CoO/Co/Si(111) with CoO thickness between 5 and 15 monolayers (ML), a phase diagram of the exchange bias has been established by way of comparing the results of zero-field cooling and field cooling. For CoO thinner than 10 ML, enhanced coercivity is observed because of the existence of nano-sized CoO particles at the interface. For CoO thicker than 15 ML, non-zero exchange field is observed because the magnetic anisotropy is large enough. For a Co/Ag-Si √3 × √3/Si(111) system, Co overlayer has been deposited on the top of Ag-Si √3 × √3/Si(111) surface alloy. For Co thinner than 4.38 ML, no Kerr signal is detected in the longitudinal configuration. The easy axis of magnetization for Co/Ag-Si √3 × √3/Si(111) is in the surface plane. By extrapolating the data for Kerr signal versus the Co thickness, the zero intercept shows no magnetic dead layer. This shows that the Ag-Si √3 × √3/Si(111) surface alloy is efficient for preventing the silicide formation between the Co layer and the silicon substrate. From the cryogenic treatments of the specimens, the Curie temperature of 3.65 ML Co/Ag-Si √3 × √3/Si(111) is between 275 and 300 K. while that of 3.51 ML Co/Ag-Si √3 × √3/Si(111) is below 150 K. In addition, my designs and efforts on the movement and reestablishment of the ultrahigh vacuum system have been discussed.
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Lin, Ying-Chang, and 林楹璋. "Organic Functionalization on Si(111) surface." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/48288828985229407380.
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Zheng, Huang-Xian, and 鄭晃翔. "Scanning Tunneling Spectroscopy of Si Magic Cluster on Si(111) Surface." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/07166404773801604613.
Full textAbstract:
碩士國立臺灣大學
物理研究所
96
On Si (111) surface, there exists a special type of Si magic cluster which has a uniform size and high thermal stability. This kind of clusters has been found to play an important role in mass transport, electromigration, step fluctuations, epitaxial growth and phase transformation. We use scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) to measure the local density of state of Si magic clusters and find that their I-V curves are very different from that of 7×7 surface. In addition, we analyze the spectra of Si magic clusters and find that there exists an energy separation of about 1eV near the Fermi level. We also compare the spectra of Si magic clusters with that of 7×7, so we can interpret the image contrast between Si magic clusters and the 7×7 reconstruction at different tunneling polarities.
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Chen, Liang-Yu, and 陳亮宇. "Formation of Si island on the Si(111)-(7×7)surface." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/hq7858.
Full textAbstract:
碩士國立中正大學
物理系研究所
107
We heated the surface of Si(111) to 1250C and then thermally annealing to room temperature to obtain a complete clean Si(111)-(7×7) reconstruction surface. We further vaporize the germanium with different coverage on the substrate, and heat the germanium substrate with different heating time or different temperatures to control the structure of the crystal layer. We used the Scanning Tunneling Microscope (STM) to observe the behavior and the crystal growth structure of the atoms on the surface, and further analyze the difference behavior of the crystal atoms in the large terrace or step. In our experiments, we have observed some results that have not been discussed in the literature, including a close-arranged or rectangular-arranged germanium atomic structure, and the evaporation of germanium on the germanium substrate to produce irregular defects after heating.The results are quite different with homoepitaxy’s expected results. According to the simple crystal growth nucleation theory, as the heating time increases and the heating temperature increases, the small islands will aggregate with each other to form a large island. We also observed this phenomenon in the experiment; but if the heating temperature is not enough, no matter how long the heating is.The island structure is unaffected. In addition, we have observed that the islands of germanium atoms that are closer to the steps on the small terrace will gradually disappear even at lower temperatures. When we heating the surface to 700C, the islands on the large and small terrace almost disappear, and the structure of the steps changes from a regular straight line to an irregular structure. Ｋeyword:STM, silicon, cluster size
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吳璧如. "Adsorptions of hydrogen on Si(111)(1x1)." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/91680382756798731802.
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Po-Chun, Kuo, and 郭博駿. "Platinum Formation on Si(111)-7x7 Surface." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/4z2e4r.
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碩士國立中興大學
物理學系所
103
The Formation of metal silicide has attracted much attention because of its low resistivity and ohmic contact in semiconductor devices. As semiconductor device get smaller, the size effect becomes more and more important. The effect of size variation in nanoscale has also led to various physical in materials. In this work, the effect of deposited time on the structure and electronic property of platinum atoms deposited on silicon (111) surface are investigated by thermal evaporation .UHV-STM was used to check the surface morphology, the results show that the platinum atoms is self-assembled as a atomic chain with irregular arrangement the results show that on the surface. In the following, the sample was annealed at high temperature, low evaporation amount of the sample rearrange to the irregular atomic long-chain structure with [1 ̅1 ̅2] direction, and which the high amount of sample deposition will form a large island structure covers the surface. We infer that the difference between the two results, is caused by different deposited amount, the attraction between the platinum atoms and the substrate surface are affected. Finally, by use STS measurements, measuring the dI / dV curve, and to explore the relationship between the energy gap and the surface structure. The original 7 × 7 reconstructed surface energy gap of 1.17eV, disorder region is 0.97eV, and long chain structure significantly improves band gap becomes 1.68eV, and a large island structure is reduced to 1.04eV.
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Chen, Cing-Hong, and 陳慶紘. "Tantalum silicides on the Si(111) surface." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/caas9r.
Full textAbstract:
碩士國立清華大學
物理系
105
In the past, the research of ion beam sputtering (IBS) emphasized on how the incidence angle, ion energy and the flux of ion beam change the patterns formed on the sputtered substrates. The influence of metal impurities produced in the IBS process was usually ignored. In recent years, due to the metal co-deposition, the metal impurities has been evaluated as a key role in the formation of nano-patterns on the substrate surfaces. Therefore, it attracted the interest of many researchers. IBS has the advantage to carry out the deposition of metals of high-melting points which cannot be achieved easily by thermal evaporation in the past. In this research co-deposition of tantalum by IBS on the Si(111) surface to form tantalum silicides is our subject. The IBS conditions in our experiments are: a 2-keV Ar+ ion beam strikes the Si(111) surface at an incidence angle 30o to the surface normal. A tantalum sheet is positioned perpendicularly to the Si(111) substrate. When ISB is performed, both Ta sheet and Si(111) substrate are sputtered. The temperature of Si(111) substrate is kept at room temperature and 1000 K when IBS is carrying out. We observe the sputtered surface with STM at the distances of 0.9 mm, 1.2 mm, 1.5 mm, 1.8 mm and 2.1 mm from Ta sheet after sputtering followed by a post-annealing. Our goal is to investigate the structures and distributions of all possible surface features formed in the sputtering-annealing process. After post-annealing at 1293 K, we found two structures for 2D islands, both have metallic ehavior under STM imaging.The first one is √3×√3 structure with domains distributed on island surface.The second one is a honeycomb structure with interatomic separation 0.31 nm and covers the entire island surface without domain. So far we do not know its structure.In the experiment of IBS on hot Si(111) substrate at 1000 K, we found a semiconductor-like 2D island which has a √7×√7 structure.The 3D islands grow bigger irreversibly upon annealing. According to Si-Ta phase diagrams, the structure of 3D islands should be TaSi2. In our experiment, we try to find out the changes of 2D and 3D islands formed after the co-deposition of Ta on the Si(111) surface at different positions and Si substrate temperatures. We found three structures for 2D island and we conclude that the structure of 3D island is TaSi2. However, our conclusions of the structures for 2D islands are short of the reconfirmation of theoretical work. With the theoretical results, the structures of 2D islands can be determined correctly.
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Chou, Che-Fu, and 周哲甫. "Formation of PtSi on Si(111) surface." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/47226826742890167532.
Full textAbstract:
碩士國立中興大學
物理學系所
98
The reconstruction of platinum adsorption on Si (111)-7x7 r surface were studied by using ultra high vacuum scanning tunneling microscope (UHV-STM). There are three kinds of island structures on Si(111)-7x7 surface. They are single island on terrace , island with hole structure on terrace and the island along at steps. The island at the different position on Si(111)-7x7 is the same structure. The island structure is Pt siliside island (6.28x6.28) . At the different bias, the island structures image by using STM like different structures. Actually, they are the same structure. We can mark the corner hole position of Si (111)-7x7, the blue point, and then extend to the island structures to calculate the island structures ,finally we can sure they are the same island structure and have the same lattice constant. The reason for form the island structure is the Si atoms diffusion from the Si(111)-7x7 surface and Pt atoms interaction. The Si atoms diffusion from the Si(111)-7x7 surface because we anneal let sample at the high temperature break the band ,so that the Si atoms diffusion .We compare with order metals , Au and Cu ,they all have the same inference. On the disorder area，we can deposit Pt and anneal to form the island structure . And we calculate the island structure on the disorder area by the Si (111)-7x7 lattice constant, they have the same lattice constant. We conclusion so reached the same reason from the Si atom diffuse form the surface, Si atoms diffusion from the Si(111)-7x7 surface because we anneal let sample at the high temperature break the band .