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1
GRAZIANETTI, CARLO. « Scanning tunneling microscopy investigation of III-V compound semiconductors and novel 2D nanolattices ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50028.
Texte intégralRésumé :
The research activity described in this thesis is mainly devoted to study the fundamental properties of alternate channel materials to bulk silicon. Indeed, there is consensus, in the scientific and industrial community, that silicon is approaching its ultimate scaling limit. Today, increasing the performance of integrated circuits by scaling silicon metal-oxide-semiconductor field effect transistor (MOSFET) is becoming more and more difficult and, therefore, a systematic survey of possible alternate solutions should be considered. This purpose is taken into account by exploring two paradigmatic candidates, namely, a promising III-V semiconductor, In0.53Ga0.47As(001), and a novel two-dimensional (2D) material, silicene, the silicon counterpart of graphene, which does not exist in nature. The former represents a mid-term option fully compatible with silicon-based processing, in a More Moore strategy, while the latter represents a completely different approach that can be envisioned for ultimate device downscaling either in a More Moore perspective or even further for More than Moore prospects. Such a systematic survey has to be carried out with probes which might consider the atomic properties, since the progressive shrinking of devices dimensions is pointing towards atomic-scale. In this framework, the choice of Scanning Tunneling Microscope (STM) represents a suitable probe which can address either the morphological properties or the electronic ones through Scanning Tunneling Spectroscopy (STS), which is the most powerful STM-related capability, since it allows for atomic-scale characterization of the local density of states (LDOS) of the sample. The local electronic properties of In0.53Ga0.47As are investigated at the interface with Al2O3. Two pristine surfaces, the As-rich (2x4) reconstruction and the group-III-rich (In/Ga) (4x2) reconstruction are scrutinized by STM. STS shows that for both n-type doped reconstructions the Fermi level is initially pinned near the valence band. However, upon in situ growth of the Al2O3 thin film by Molecular Beam Epitaxy (MBE), partial unpinning occurs, while post-deposition annealing restores the original pinned condition in a different extent depending on the surface reconstruction. This behavior is rationalized in terms of an interface dipole induced by positive charges in the as-grown oxide, which are suppressed upon annealing. Hence, this comparison shows that the (2x4) reconstruction is more favorable for application-oriented perspectives of In0.53Ga0.47As as an active channel in MOSFET devices. Despite the high expectations, graphene, the nowadays best-known 2D material, has severe limitations for logic electronics due to its gapless nature. These limitations could be possibly overcome by silicene (and germanene). Here, a thoroughly study about the formation by MBE of various 2D phases of silicon on the Ag(111) surface depending on coverage and substrate temperature is reported. The resulting scenario is depicted by several silicene phases showing different periodicities and orientations with respect to the silver substrate. These structural phases stem from the intrinsic flexibility of silicene originated by its buckled structure, in contrast to graphene. The periodically modulated LDOS of silicene superstructures evidenced by STS spectra could be ascribed to the symmetry breaking in the triangular sublattices originated by the presence of buckled honeycomb lattice. The instability of silicene upon air exposure leads to the necessary encapsulation which is provided by an aluminum-based capping layer. This configuration allows the transfer of the samples for ex situ Raman spectroscopy measurements. Both experimental and theoretical Raman spectra show the presence of E2g mode, namely G peak in graphene, which is the fingerprint of honeycomb lattice, and by other vibrational modes activated by the intrinsic disorder related to the buckling. Both theoretical models and experiments proved that silicene phases have different mixture of sp2-sp3 hybridization that means different bond lengths, bond angles, and buckling parameters. Moreover these phases of silicene exhibit different electronic properties, ranging from semiconducting to semi-metal character. The perspective of future high performance logics should probably experience an intermediate step at III-V compound semiconductors, but it is very likely to expect that 2D materials will remain a hot topic in future electronics.
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Barthélémy, Agnès. « Etude des super-reseaux fe (001)/cr (001) et fe (001)/ag (001) ». Paris 11, 1991. http://www.theses.fr/1991PA112032.
Texte intégralRésumé :
Cette these presente l'etude experimentale de super-reseaux magnetiques fe/cr et fe/ag elabores par epitaxie par jet moleculaire. Dans les super-reseaux fe/ag nous avons mis en evidence la presence d'une forte anisotropie d'interface qui aligne l'aimantation perpendiculairement au plan des couches pour des epaisseurs de fe inferieures a 10 a. Cette anisotropie varie peu avec la temperature. Nous avons egalement etudie sur ces super-reseaux, la thermodynamique des systemes bidimensionnels a partir de la variation en temperature de l'aimantation. Dans le cas des super-reseaux fe/cr, nous nous sommes tout d'abord interesses au phenomene de couplage d'echange antiferromagnetique qui aligne antiparallelement les aimantations de deux couches de fe voisines. Nous avons etudie ce couplage par des mesures d'aimantation, de couple magnetique et de diffraction de neutrons et nous avons determine sa variation en fonction de l'epaisseur de cr et de la temperature. Cette these regroupe egalement les resultats experimentaux obtenus sur la dependance en epaisseur, en nombre de couche et en temperature d'une propriete nouvelle qui resulte de la structure en super-reseau: la magnetoresistance geante. Ce travail experimental s'accompagne du developpement d'un modele theorique de la magnetoresistance geante. Ce modele est semi-classique, de type fuchs-sondheimer, et permet de bien mettre en evidence les parametres importants qui regissent ce phenomene
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Wang, Yuekun. « In0.53Ga0.47As-In0.52Al0.48As multiple quantum well THz photoconductive switches and In0.53Ga0.47As-AlAs asymmetric spacer layer tunnel (ASPAT) diodes for THz electronics ». Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/in053ga047asin052al048as-multiple-quantum-well-thz-photoconductive-switches-and-in053ga047asalas-asymmetric-spacer-layer-tunnel-aspat-diodes-for-thz-electronics(5fd73bd5-aef3-476b-be1b-7498da3f9627).html.
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This thesis is concerned with terahertz (THz) technology from both optical and electronic approaches. On the optical front, the investigation of optimised photoconductive switches included the characterisation, fabrication and testing of devices which can generate and detect THz radiation over the frequency range from DC to ~ 2.5 THz. These devices incorporated semiconductor photoconductors grown under low temperature (LT) Molecular Beam Epitaxy (MBE) conditions and using distributed Bragg reflectors (DBRs). The material properties were studied via numerous characterisation techniques which included Hall Effect and mid infrared reflections. Antenna structures were fabricated on the surface of the active layers and pulsed/continuous wave (CW) signal absorbed by these structures (under bias) generates photocurrent. With the help of the DBRs at certain wavelengths (800 nm and 1550 nm), the absorption coefficient at the corresponding illumination wavelength increased thus leading to significant increase of the THz output power while the materials kept the desirable photoconductive material properties such as high dark resistivity and high electron mobility. The inclusion of DBRs resulted in more than doubling of the THz peak signals across the entire operating frequency range and significant improvements in the relative THz power. For the THz electronic approach, a new type of InP-based Asymmetric Spacer Tunnel Diode (ASPAT), which can be used for high frequency detector, was studied. The asymmetric DC characteristics for this novel tunnel diode showed direct compatibility with high frequency zero-bias detector applications. The devices also showed an extreme thermal stability (less than 7.8% current change from 77 K to 400 K) as the main carrier transport mechanism of the ASPAT was tunnelling. Physical models for this ASPAT diode were developed for both DC (direct current) and AC (alternating current) simulations using the TCAD software tool SILVACO. The simulated DC results showed almost perfect matches with measurements across the entire temperature range from 77 K to 400 K. From RF (radio frequency) measurements, the intrinsic diode parameters were extracted and compared with measured data. The simulated zero biased detector circuits operating at 100 GHz and 240 GHz using the new InGaAs-AlAs ASPAT diode (4*4 micrometer square) showed comparable voltage sensitivities to state of the art Schottky barrier diodes (SBDs) detectors but with the added advantage of excellent thermal stability.
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Heyd, Darrick Vaughn. « Photodissociation of methyl bromide adsorbed on LiF(001), NaCl(001), and MgO(001) ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0001/NQ27950.pdf.
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Charcape, Galo Emilio Sisniegas. « Crescimento de In0.52Al0.48As e In0.53Ga0.47As sobre InP por MBE ». Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14012009-094440/.
Texte intégralRésumé :
Neste trabalho a epitaxia por feixes moleculares (Molecular Beam Epitaxy: MBE) foi utilizada para crescer estruturas de gases bidimensionais a base de In0.53Ga0.47As/ In0.52Al0.48As sobre substrato de fosfeto de índio (InP) e analisar suas propriedades estruturais. elétricas e óticas através de técnicas de caracterização, tais como efeito Hall, fotoluminescência (FL). Shubnikov-de Haas (SdH) e microscopia eletrônica de varredura (MEV). A calibração dos parâmetros de crescimento tais como a taxa de crescimento e a composição das ligas In0.53Ga0.47As/ In0.52Al0.48As foi feita através da observação das oscilações da da difração de elétrons de alta energia observado em reflexão (Reflection High-Energy Electron Difraction : RHEED) A densidade de dopante tipo n (em nosso caso. 0 silício) foi determinada posteriormente através de medidas de efeito Hall usando a técnica de Van der Pauw. Os resultados da Fotoluminescência mostram uma transição doador-banda com largura a meia altura (Full Width at Half Maximum : FWHM) de aproximadamente 23 meV, para a liga de In0.52Al0.48As. A formação de gás bidimensional nestas mesmas amostras tem sido observado indiretamente pela ocorrência de oscilações SdH.In this work Molecular Beam Epitaxy (MBE) was used to growth bidimensional gas structures based on In0.53Ga0.47As/ In0.52Al0.48As on Indium Phosfate substrate (lnP) Structural. electrical and optical properties were analyzed by characterisation techniques such as Hall eflect, photoluminescence (PL), Shubnikov-de Haas (SdH) and Scanning Electron Microscope (SEM) Growth parameter calibration such as growth rate and alloy composition of In0.53Ga0.47As/ In0.52Al0.48As was determined through observation of Reflexion High-Energy Electron Diffraction (RHEED) oscillation. Density of type dopant (in our case silicon Si) was obtained by. Hall effect measurements using Van der Pauw geometry Photoluminescence results show donor to band transition with Full Width at Half Maxima (FHWM) of approximatly 23meV, for the In0.52Al0.48As alloy. Bidimensional gas formation was indirectly observed in these samples through SdH oscillations.
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Deutsch, Thierry. « Modélisation des multicouches métalliques Au(001)/Ni, Ag(001)/Ni et Au(001)/Co ». Grenoble INPG, 1995. http://www.theses.fr/1995INPG0096.
Texte intégralRésumé :
L'objet de cette these est la simulation des multicouches metalliques au(001)/ni, ag(001)/ni et au(001)/co elaborees par epitaxie par jets moleculaires. Les systemes etudies ont la particularite de presenter une grande difference de parametre de maille (de l'ordre de 16%). Un potentiel semi-empirique base sur la methode des liaisons fortes permet de modeliser les interactions atomiques entre l'au, l'ag, le ni et le co. Des simulations a o k (relaxation numerique) et a 300 k (dynamique moleculaire) ont mis en evidence une transition de structure du film de ni ou de co: pour une epaisseur de 5 monocouches d'une structure quadratique centree, le ni ou le co se transforme en une structure hexagonale. L'etude de la stabilite et des contraintes internes du film de ni sur un substrat au(001) est abordee. Une methode ab-initio (lmto) permet d'affiner nos resultats. La croissance de ces multicouches par dynamique moleculaire a mis en evidence un mecanisme d'echange entre les atomes deposes (ni ou co) et les atomes du substrat (au ou ag). Les energies d'activation de divers processus de diffusion sont en outre calculees. Ces resultats ont ete correles a d'autres methodes telles que le rheed, la diffraction de rayons x, l'exafs et la microscopie electronique a haute resolution
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Dooley, Roger Benesh Greg. « Surface magnetism of Ni(001), Co(001), and Fe(001) an embedding Green function approach / ». Waco, Tex. : Baylor University, 2007. http://hdl.handle.net/2104/5051.
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Ivashchenko, V., S. Veprek et V. Shevchenko. « Comparative first-principles molecular dynamics study of TiN(001)/SiN/TiN(001) and TiN(001)/SiC/TiN(001) interfaces in superhard nanocomposites ». Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20546.
Texte intégralRésumé :
Heterostructures TiN(001)/SiN/TiN(001) and TiN(001)/SiC/TiN(001), with one
monolayer (ML) of interfacial SiN and SiC, respectively, inserted between five monolayer
thick B1-TiN, were investigated using first-principles quantum molecular dynamics
(QMD) calculations. The temperature dependent QMD simulations at 300 K in
combination with subsequent variable-cell structural relaxation revealed that the
TiN(001)/SiN/TiN(001) interface exists as pseudomorphic B1-SiN layer only at 0 K,
and as a superposition of distorted octahedral SiN6 and tetrahedral SiN4 units aligned
along the (110) direction at a finite temperature. Thus, at 300 K, the interfacial layer is
not epitaxial. Instead it consists of aggregates of the B1-SiN-like and Si3N4-like distorted
clusters. However, in the the TiN(001)/SiC/TiN(001) heterostructures, the interfacial
layer remains epitaxial B1-SiC at 0 K as well as at 300 K, with only a small shift of
nitrogen atoms on both sides of the interface towards the silicon atoms. A comparison
with the results obtained by earlier "static" ab initio DFT calculations at 0 K shows the
great advantage of the QMD calculations that allow us to reveal structural reconstructions
caused by thermal activation.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20546
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Farmer, Corrie David. « Fabrication and evaluation of In0.52Al0.48As/In0.53Ga0.47As/InP quantum cascade laser ». Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/6883/.
Texte intégralRésumé :
InP-based quantum cascade (QC) lasers were fabricated following the design reported by Faist et al. with the initial aim of applying them in gas sensing applications. The lasers were characterised by our collaborators, Cockburn et al. Unfortunately, the performance of our QC lasers (QCLs) did not live up to expectations, and the gas sensing objectives became replaced with resolving the issues of their poor performance. This was achieved through a mixture of laser fabrication, characterisation, and optical and thermal waveguide modelling. The devices fabricated included mesa-etched QCLs, shallow-etched QCLs, and novel native-oxide defined QCLs.2D thermal modelling using a commercial finite element modelling package was carried out to solve the 2D non-linear thermal diffusion equation for all of the structures listed above, as well as for InP-clad and buried heterostructure configurations. The temperature elevations, distributions and heat flow vectors were calculated under high, but not unrealistic thermal power generation in the active waveguide core. The relative effectiveness at dissipating heat was judged using these results. The modelling indicated the presence of high temperatures and thermal gradients across the active waveguide core under continuous wave (CW) operation. The thermal resistance derived through the use of the thermal modelling agreed very well with that calculated by Faist et al. from experimental data. The optical modelling, which was instrumental in resolving the anomalous behaviour of our QC lasers, comprised of two parts. First, modelling of the dielectric permittivity gave values of n and a for InP, In0.52Al0.48As and In0.53Ga0.47As as a function of the free-carrier density and wavelength. The calculations were made using single and multiple-oscillator models with a free-carrier contribution in the form of a classical Drude expression. The dependencies of the electron mass and electron mobility on the free electron density were taken in the calculations. These values were used to perform 2D optical modelling of the waveguide using a commercial, fully vectorial waveguide mode solver. This yielded the effective index, confinement factor, facet reflectivity, waveguide loss and far-field distribution for each mode. These, in turn, were used to calculate the threshold gain for each mode. Perhaps the most important findings were the prediction of the existence of higher order transverse modes, that these modes can have low values of gth (comparable or better than that of the fundamental mode of the waveguide) and that the collection efficiency will vary dramatically from mode to mode. The modelling also indicated that the performance of the QCLs would suffer greatly with an increase in the InP substrate doping level, even just from 1x1018 cm-3 to 3x1018 cm-3.
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Aubel, Dominique. « Apport des techniques de photoémission à la connaissance des hétérostructures Ge/Si(001), Si/Ge(001), Si1-xGex/Si(001) et Si1-xGex/Ge(001) ». Mulhouse, 1995. http://www.theses.fr/1995MULH0412.
Texte intégralRésumé :
Les premières phases de la croissance à température ambiante (TA) et 400°C des deux hétérostructures Si/Ge(001) et Ge/Si(001) ont été étudiées par des techniques de surface comme la spectroscopie de photoélectrons X(XPS) et UV(UPS) et la diffraction d'électrons lents (LEED). Un effort particulier a été fait pour développer la dernière née des méthodes d'investigations structurales dérivée de l'XPS à savoir la diffraction de photoélectrons X(XPD). L'analyse fine de l'émergence des signatures XFD et la mesure des contrastes sur les pics de diffusion vers l'avant en fonction du recouvrement, apportent des renseignements précis concernant l'empilement des atomes dans les couches et donc les modes de croissance initiaux. En second lieu, nous avons élaboré par voie MBE des hétérostructures d'alliages Si1-xGex sur Si(001) pour x faible et Si1-xGex sur Ge(001) pour x fort. Ces couches ont été fabriquées à 400°C par co-évaporation et analysées in situ par XPS, UPS, LEED et par XPD, avant d'être analysées ex situ par XRD, RBS, Raman dans le cadre de différentes collaborations. La conjonction de ces caractérisations ex situ avec nos études de surface in situ, nous a permis de déterminer la qualité cristallographique, la composition en Ge et l'état de contrainte de ces alliages Si1-xGex. La terminaison de surface de ces alliages Si1-xGex a été sondée in situ par des expériences de nitruration initiale qui ont revélé une forte ségrégation du Ge à la surface de ceux-ci. En troisième lieu, des résultats exploratoires sont présentés sur la nitruration thermique des alliages Si1-xGex soulignant la sélectivité de nitruration thermique entre Si et Ge. Contrairement au processus thermique, la nitruration assistée par plasma permet d'obtenir une nitruration simultanée des deux éléments de l'alliage
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Zavaliche, Florin. « The metal-semiconductor interface Fe-Si(001) and Fe-InP(001) / ». [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965216217.
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Gastelois, Pedro Lana. « Propriedades estruturais e magnéticas de filmes ultrafinos de Fe/Rh(001), Ni/Rh(001) e Ni(Pd(001) e de camadas acopladas de CoO/Ni/Pd(001) ». CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2015. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=351.
Texte intégralRésumé :
NenhumaIn this work, the strong correlation between the structural and magnetic properties in systems of reduced dimensionality is explored. Particularly, the magnetic properties of epitaxially grown ultrathin films and coupled layers, as a function of their constitution, thickness, structure and temperature, are studied. The investigated systems illustrate that perpendicular magnetic anisotropy in thin films can be achieved via tetragonal distortion or perpendicular exchange coupling. Specifically, Fe films grown on Rh(001) are examined, with emphasis both on their spin reorientation transition and on a complex magnetic structure existing at the first Fe monolayer. Contrasted to Fe/Rh(001), Ni films grown on Rh(001) and on Pd(001) are studied, highlighting the reverse spin reorientation transition and the perpendicular magnetic anisotropy originating from the large tetragonally distorted structure created by epitaxy. Concurrently, the indication of induced moments in the Pd(001) substrate in this system is also considered. Additionally, Ni films grown on Pd(001) covered with CoO antiferromagnetic layers are explored, emphasizing the effect of exchange coupling on their magnetic perpendicular anisotropy. Finally, the system consisting of a CoO single layer grown directly on Pd(001) is investigated, highlighting the indication of a ferromagnet under-layer, induced in the Pd(001) substrate by the CoO antiferromagnetic layer.
Neste trabalho, a forte correlação entre a estrutura e as propriedades magnéticas de sistemas de dimensionalidade reduzida, é explorada. Em particular, as propriedades magnéticas de filmes e camadas acopladas epitaxiais, em função de sua constituição, espessura, estrutura e temperatura são investigadas. Os sistemas investigados exemplificam que a anisotropia magnética perpendicular em filmes finos pode ser alcançada via distorção tetragonal ou pelo acoplamento de troca perpendicular. Especificamente, filmes de Fe crescidos em Rh(001) são investigados com ênfase em sua transição de reorientação de spin e em uma estrutura magnética complexa presente na primeira monocamada de Fe. Em contraste com Fe/Rh(001), filmes de Ni crescidos em Rh(001) e em Pd(001) são estudados destacando-se a transição de reorientação de spin reversa e a anisotropia magnética perpendicular, com origem na estrutura tetragonal distorcida criada por epitaxia. Concorrentemente, a indicação de momentos magnéticos induzidos no substrato de Pd(001) nesse sistema também é considerada. Além disso, filmes de Ni crescidos em Pd(001), cobertos com camadas de CoO antiferromagnéticas, são exploradas dando ênfase no efeito de acoplamento de troca em sua anisotropia magnética perpendicular. Por fim, o sistema constituído de uma camada de CoO, crescida diretamente em Pd(001), é investigado, destacando-se a indicação de uma camada ferromagnética induzida no substrato de Pd(001) pela camada antiferromagnética de CoO.
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Blomqvist, Peter. « Structural and Magnetic Properties of Fe/Co (001) and Fe/V (001) Superlattices ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5134-9/.
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Damm, Thorsten. « Sputterepitaxie von Eisenfilmen und Eisen-Silizium-Eisen-Dreilagenschichtsystemen auf GaAs(001) und MgO(001) ». [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971700044.
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Kutnyakhov, Dmytro [Verfasser]. « Imaging spin-filter efficiency of W(001) and Ir(001) single crystals / Dmytro Kutnyakhov ». Mainz : Universitätsbibliothek Mainz, 2014. http://d-nb.info/1064139167/34.
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Silva, Roberto Claudino da. « Geometria, Estabilidade e Estrutura Eletrônica das Superfícies GaAs(001) : Te e InAs(001) : Te ». Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-12062012-131546/.
Texte intégralRésumé :
Estudamos a adsorção de Te em superfícies de GaAs(001) e InAs(001) com periodicidades 1x1, 1x2, 2x1 e 2x2, para as concentrações de telúrio Tc= 0, 1/4, 1/2, 3/4 e 1. Realizamos cálculos dentro do formalismo do funcional da densidade empregando pseudopotenciais de norma conservada. Para a relaxação das estruturas empregamos a dinâmica molecular de Car e Parrinello. Nossos resultados apontam para uma redução na estabilidade das superfícies na proporçã em que aumenta a concentração de Te na uperfície. A cobertura de As (Tc = 0) é energeticamente mais favorável que as recobertas com qualquer concentração de Te, tanto na superfície de GaAs(001) quanto na de InAs(001). Observouse ainda nas superfícies com Tc = 0 Tc = 1, que a dimerização dos átomos de As e da ordem de 30% mais intensa que dos átomos e Te. Comparando as dimerizações do Te nas superfícies com concentrações Tc 1/2, observamos que elas são maiores sobre o InAs(001) (célula terminada em In) que sobre o GaAs(001) terminada em Ga). Outra tendência verificada e a \"flutuação\" do Te sobre as superfícies. Para uma mesma concentração verificamos a \"preferência de adsorção\" em sítios fora da cadeia de dímeros indicando uma adsorção monoatômica. Para concentração Tc = 1 na superfície GaAs(001):Te2x2 observamos duas geometrias possíveis: uma com cadeias de dímeros seguindo o modelo \"dimerrowmissing\" e outra com dois tipos de dímeros em posições alternadas ao longo da dir~ao (110). Analisando as energias de adsorção nas duas superfícies verificamos que a adsorção sobre o InAs é mais favorável que sobre o GAs. Analisamos ainda a estrutura eletrônica das superfícies em todas as reconstruções e concentrações consideradas e verificamos anda o caráter semicondutor das superfícies com concentração Tc = 1/2.We have carried out ab initio density functional calculations to investigate the adsorption of Te on GaAs(001) and lnAs(001) surfaces as a function of Te surface coverage: Tc = 0, 1/4, 1/2, 3/4, 1. In order to determine the equilibrium atomic positions, the geometry was relaxed according he calculated total energy and forces following the Car Parrinello approach for molecular dynamics. Our calculations indicate that a full monolayer of As (Tc = 0) is energetically more favourable than any of the studied coverage of Te (Tc = 1/4, 1/2, 3/4, 1), where the stability is educed with increasing Te coverage. The dimerization of surface As atoms is about 30% more intense than surface Te atoms. Comparing the Te dimerization on InAs(001), In terminated, and aAs(OOI), Ga terminated, we observed that the Te atoms dimerize more over lnAs than GaAs surface. Another observation is the tendency of the Te atoms to \'l1oat\" from the surface with increasing coverage. For the same concentrations of Te the atoms \"prefer\" to be adsorbed on the offchain sites indicating a monoatomic adsorption. The adsorption energy of Te on InAs(001) is more favorable than GaAs(001). We also determined the surface band structure for all reconstructions and Te concentrations, veryfying the semiconductor nature for Tc = 1/2.
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Pepper, David Jonathan. « Confidence in PISA : validating an international assessment of student self-efficacy in mathematics ». Thesis, King's College London (University of London), 2014. http://kclpure.kcl.ac.uk/portal/en/theses/confidence-in-pisa(96b21acf-cf79-471d-8f18-af97b5c1d5be).html.
Texte intégralRésumé :
Student participation and attainment in mathematics is an issue in education policies and practices for many countries. Some academics, teachers and policy makers claim that student attitudes in mathematics exercise a decisive causal influence on participation and attainment in mathematics. To ensure that education policies and practices are well-evidenced, it is important that assessments of these attitudes are sufficiently validated for such claims. The influential Organisation for Economic Co-operation and Development (OECD) Programme for International Student Assessment (PISA) includes assessments of student self-confidence in mathematics. This involves two sets of questionnaire items, with one set relating to self-efficacy and the other set relating to selfconcept. While the self-concept items refer to the mathematics domain as a whole, the self-efficacy items refer to individual mathematics tasks. Self-efficacy has been incorporated in models of self-regulated learning and, although one model indicates that self-efficacy may be significant for formative assessment, there is disagreement about relations between self-efficacy, participation and attainment. Although there have been several studies of mathematical self-efficacy, their assessments have generally lacked sufficient validations. The OECD validation of the PISA mathematical self-efficacy assessment itself lacks transparency and requires more evidence. The present study provides an independent validation of the assessment and uses mathematical self-concept as a point of comparison. The validation has a mixed methodology integrating evidence from the PISA 2003 data set and documentation for 41 countries with cognitive interviewing of students in England, Estonia, Hong Kong and the Netherlands. The validation identifies threats to validity that weaken extrapolation from the assessment to real-world situations, particularly in Hong Kong. These threats are traced to the formulation of the mathematics tasks in the self-efficacy items. The findings have implications for the interpretation and development of mathematical self-efficacy assessments as the basis for understanding relations with participation and attainment.
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Ovsyanko, Mikhail Mikhaylovich. « Ion sculpting of Cu(001) ». Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/51109.
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Saluru, Sarat K. « Projection of TaSiOx/In0.53Ga0.47As Tri-gate transistor performance for future Low-Power Electronic Applications ». Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78028.
Texte intégralRésumé :
The aggressive scaling of silicon (Si) based complementary metal-oxide-semiconductor (CMOS) transistor over the past 50 years has resulted in an exponential increase in device density, which consequentially has increased computation power rapidly. This has pronounced the necessity to scale the device's supply voltage (VDD) in to order to maintain low-power device operation. However, the scaling of VDD can degrade drive current significantly due to the low carrier mobility of Si. To overcome the key challenges of dimensional and voltage scaling required for low-power electronic operation without degradation of device characteristics, the adoption of alternate channel materials with low bandgap with superior transport properties will play a crucial role to improve the computation ability of the standard integrated circuit (IC). The requirement of high-mobility channel materials allows the industry to harness the potential of III-V semiconductors and germanium. However, the adoption of such high mobility materials as bulk substrates remains cost-prohibitive even today. Hence, another key challenge lies in the heterogeneous integration of epitaxial high-mobility channel materials on the established cost-effective Si platform. Furthermore, dimensional scaling of the device has led to a change in architecture from the conventional planar MOSFET to be modified to a 3-D Tri-gate architecture which provides fully depleted characteristics by increasing the inversion layer area and hence, providing superior electrostatic control of the device channel to address short channel effects such as subthreshold slope (SS) and drain induced barrier lowering (DIBL). The Tri-gate configuration provides a steeper SS effectively reducing leakage current (IOFF), thereby decreasing dynamic power consumption and increasing device performance. Recently, Tantalum silicate (TaSiOx) a high-k dielectric has been shown to exhibit superior interfacial quality on multiple III-V materials. However, there is still ambiguity as to the potential of short-channel devices incorporating alternate channel (III-V) materials which is the basis of this research, to demonstrate the feasibility of future high-mobility n-channel InGaAs material integration on Si for high- speed, low-power, high performance CMOS logic applications.Master of Science
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Ravlić, Robert. « Magnetische Studien der Cr(001)-Oberfläche und des Fe-Cr(001)-Systems mittels spinpolarisierter Rastertunnelspektroskopie ». [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968651593.
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Hu, Wei. « Monte Carlo simulations of the CO¦2/NaCI(001) and CH¦3Br/LiF(001) systems ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq25989.pdf.
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Bochi, Gabriel 1969. « Magnetic anisotropy in epitaxial Ni/Cu (001) thin films and Cu/Ni/Cu (001) sandwiches ». Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11514.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.Vita.
Includes bibliographical references (leaves 156-161).
by Gabriel Bochi.
Ph.D.
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Corbett, Joseph P. Corbett. « Spin Structures of the L10-MnGa(001) and α-Cr(001) Surfaces ». Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou15156693279871.
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Berdot, Thibaut. « Mouvement du spin de l’électron dans les systèmes Fe/Ag(001) et MgO/Fe(001) ». Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/BERDOT_Thibaut_2011.pdf.
Texte intégralRésumé :
Ce travail apporte une contribution à l'étude du mouvement du spin en géométrie de réflexion sur des systèmes ferromagnétiques. Une corrélation entre la relaxation et les propriétés de réflexion dépendantes en spin est montrée. Tout d'abord, le système Fe/Ag(OOI) a été étudié. Le résultat prédominant mis en évidence est l'obtention d'un angle de précession de 180°, soit la valeur maximale qu'il est possible de détecter. Cette précession de spin géante a été attribuée à la relaxation du paramètre de maille durant la croissance. Nos calculs ab initio confirment cette hypothèse. La deuxième partie de cette thèse correspond à l'étude du système MgO/Fe(OOI). Une très forte sensibilité des angles du mouvement du spin à l'épaisseur de MgO est observée pour certaines énergies. Ainsi, à 7eV, 0,15 MC de MgO sont suffisantes pour réduire la valeur de l'angle de précession de moitié. Les expériences par effet Kerr magneto-optique n'ont montré aucune modification significative de l'aimantation de Fe durant le dépôt de MgO. Cependant, certaines études expérimentales montrent que le dépôt de MgO induit une relaxation hors-plan de la couche de Fe en surface. La relaxation serait de 10% pour une épaisseur de 35 MC et pourrait induire une modification importante de la structure de bandes. Les calculs ab initio réalisés sur la base de cette hypothèse présentent un accord qualitatif avec les résultats expérimentaux et confirment l'importance de l'interface du système MgO/Fe(OOI) pour les propriétés de réflexion dépendantes en spinIn this work, we carried out spin-polarized electron reflection experiments. The infuence of the relaxation on the spin-dependant refleetion properties is shawn. First of ail, Fe/Ag(OOI) system has been studied. A precession angle of 180° has been obtained. This corresponds to the largest value that is possible to detect. We think that this effect can be explained by the relaxation of the lartice parameter during the growth. Ab initio calculations confirm this hypothesis. The second part of this work has been dedicated to the study of MgOlFe(OO1) system. A strong sensitivity of the spin motion angles ta the MgO thickness is shawn. According to Magneto-Optic Kerr effect experiments, this phenomenon cannot be explained by a modification of the Fe magnetization during the growth of MgO. However, other experimental studies demonstrate that MgO induces an out of-plane relaxation of the Fe surface layer. This relaxation could be of 10% for an MgO thickness of 0,35 ML and would induce strong changes of the electronic band structure. The qualitative agreement of our ab initia calculations with the ex peri- mental data suggests strongly that this effect is responsible for the variation of the spin motion angles and confirm that the MgOlFe(OO1) interface is important regarding the spin-dependant reflection properties
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THORPE, STEPHEN DENNY. « Dilute magnetic semiconductors : the role of Mn in GaMnAs(001) and Mn/GaAs(001) surfaces ». Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1214.
Texte intégralRésumé :
The study of interfaces between magnetic materials and semiconductors is fundamental for the development of spintronics devices as spin injection blocks. For this reason the growth of Mn-based magnetic alloys on III-V semiconductors, in particular on GaAs is an interesting topic both from theoretical and technological point of views [1]. Moreover, the investigation of the GaMnAs(001) and the Mn/GaAs(001) surfaces is essential to understand the growth process of GaMnAs itself, a prototypical diluted magnetic semiconductor. In fact, the mechanism of interstitial Mn sites defects formation is not well understood as well as the structure of the GaMnAs(001)(1×2) surface; furthermore the Mn adsorption site could play a fundamental role [2]. As a last point it has been experimentally demonstrated that Mn acts as surfactant in the growth process of InAs quantum dots on GaAs [3].
In this thesis the growth and the characterization of the GaMnAs(001) and the Mn/GaAs(001) surfaces are reported. In the first case a Molecular Beam Epitaxy (MBE) growth of GaMnAs(001) with a subsequent in situ characterization by Reflectivity Anisotropy Spectroscopy (RAS), Electron Energy Loss Spectroscopy (EELS) and Scanning Tunneling Microscopy (STM) are presented. In the second case, starting from GaAs(001) grown by MBE, the surface was investigated after Mn deposition and subsequent low temperature annealing by in situ STM, X-ray Photoelectron Spectroscopy (XPS) and Photoelectron Diffraction (PED). The aim of this work is to understand the structure of 1×2 reconstruction of GaMnAs and to understand the mechanism of the Mn-As interaction and the behavior of Mn deposited on the GaAs(001) surface.
The GaMnAs(001) surface reveals some electronic structures very similar to GaAs(001)c(4×4) [4] with an additional optical feature around 2eV attributed to the p-d hybridization between Mn (d) and As (p) [5], moreover the overall RAS spectra is very similar to GaAs(001)(1×2) surface [6] and to theoretical ab initio GaAs(001) ones [7] suggesting the presence of symmetric dimers in the GaMnAs(001) surface with a possible Mn adsorption site under the As-As dimers [8].
In the Mn/GaAs(001), after Mn deposition, LEED and RHEED patterns show that the c(4×4) reconstruction is destroyed and a faint (1×2) periodicity takes over, emerging more clearly, after the thermal treatment [9]. XPS measurements of As 3d and Mn 2p core levels before and after annealing demonstrate that the high reactivity of Mn with the surface As atoms is responsible for the surface disorder after Mn deposition. The sample annealing induces a rearrangement of the surface atoms. STM images demonstrate that the ordering of the surface responsible for the (1×2) periodicity, observed by LEED and RHEED, is characterized by structures compatible with the presence of As dimers.
[1] M. Ramsteiner, et al. Phys Rev. B 66 (2002) 081304(R).
[2] S.C. Erwin, A.C. Petukhov Phys Rev. Lett. 89 (2002) 227201.
[3] S.P. Guo, et al. J. Crystal Growth 208 (2000) 799.
[4] F. Arciprete, et al. Phys. Rev. B 68 (2003) 25328.
[5] J. Okabayashi, et al Phys. Rev. B 59, R2486 (1999)-R2489.
[6] M. J. Begarney, et al. Phys. Rev. B 62 (2000) 8092.
[7] C. Hogan, E. Placidi and R. Del Sole Phys. Rev. B 71 (2005) 041308(R).
[8] S. D. Thorpe, et al. to be published.
[9] S. D. Thorpe, et al. Superlattices and Microstructures 46, (2009) 258-265.
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Meyer, zu Heringdorf Frank-Joachim. « Goldinduzierte Nanostrukturierung vicinaler Si(001)-Oberflächen ». [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=957616368.
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Kutzer, Martin. « Oberflächenmodifikation von Si(001) mittels Se ». Master's thesis, Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200501676.
Texte intégralRésumé :
Im Rahmen dieser Diplomarbeit wurden Si(001)-Oberflächen mit Selen modifiziert und anschließend charakterisiert.
Die Herstellung der Selenpassivierungsschichten wurde in einer MBE-Anlage durchgeführt. Die Charakterisierung erfolgte durch RHEED-, LEED- und RBS-Untersuchungen.
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Braunschweig, Björn. « In-situ-Untersuchungen zur molekularen Struktur von Festkörper, Elektrolyt-Grenzflächen Platin und {[alpha]-Al2O3 (001) [Alpha-Al2O3 (001)] ». Clausthal-Zellerfeld Papierflieger, 2009. http://d-nb.info/995160821/04.
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Shaltaf, Riad. « Adsorption And Growth On Si(001) Surface ». Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604904/index.pdf.
Texte intégralRésumé :
The (001) surface of silicon has been the topic of our study in
this thesis. The clean surface, an-adatom or submonolayer
adsorption on the surface, the monolayer adsorption and its
stability conditions as well as growth simulation on the surface
were investigated using the state of the art techniques.
We have used ab initio density functional calculations
based on norm-conserving pseudopotentials to investigate the Mg adsorption on the Si(001) surface for 1/4, 1/2 and 1 monolayer (ML) coverages. For both 1/4 and 1/2 ML coverages it has been found that the most favorable site for the Mg adsorption is the cave site between two dimer rows consistent with recent experiments. For the 1 ML coverage (2 Mg atoms per 2X1 unit cell) we have found that the most preferable configuration is when both Mg atoms on 2X1 reconstruction occupy the two shallow sites. We have found that the minimum energy configurations for 1/4 ML coverage is a 2X2 reconstruction while for the 1/2 and 1 ML coverages they are 2X1.
Same method was also used to investigate the surface stress and energetics of the clean-, Sb-adsorbed-, and
Sb-interdiffused-Si(001) surface. It is found that interdiffusion
of Sb into deeper layers of Si(001) leads to a more isotropic
surface stress but corresponds to a higher total energy
configuration. As a result of competition between stress relief
and energy gain, the surface with all the Sb atoms adsorbed on top of Si(001) surface layer is predicted to have a less ordered geometry and roughness in z-direction. We have repeated the similar calculations on the Ge(001) surface for comparison.
Finally using empirical molecular dynamics method, we have
investigated the crystalline growth of silicon on Si(001) as a
function of substrate temperature and incident particle energy.
Our results show that the increase of substrate temperature
enhances the crystallinity in the film grown on the Si(001)
surface, on the other hand, the crystalline growth can be enhanced at low temperature by using higher incidence energy.
30
Shen, Xiu-Li. « Chemical beam epitaxial growth of (001) ZnS ». Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/18896.
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Roberts, Nuala. « Reconstructions on the (001) surface of silicon ». Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304390.
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Williams, Richard Spencer. « M.B.E. growth on GaAs (001) patterned substrates ». Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401946.
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Griese, Sabine. « Andreas Gardt, Mireille Schnyder u. Jürgen Wolf (Hrsg.) : Buchkultur und Wissensvermittlung in Mittelalter und Früher Neuzeit. Berlin u. Boston, 2011 (Rezension) ». De Gruyter, 2015. https://ul.qucosa.de/id/qucosa%3A23259.
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Jenkins, Charlotte. « Automatic classification and metadata generation for world-wide web resources ». Thesis, University of Wolverhampton, 2002. http://hdl.handle.net/2436/89094.
Texte intégralRésumé :
The aims of this project are to investigate the possibility and potential of automatically classifying Web documents according to a traditional library classification scheme and to investigate the extent to which automatic classification can be used in automatic metadata generation on the web. The Wolverhampton Web Library (WWLib) is a search engine that classifies UK Web pages according to Dewey Decimal Classification (DDC). This search engine is introduced as an example application that would benefit from an automatic classification component such as that described in the thesis. Different approaches to information resource discovery and resource description on the Web are reviewed, as are traditional Information Retrieval (IR) techniques relevant to resource discovery on the Web. The design, implementation and evaluation of an automatic classifier, that classifies Web pages according to DDC, is documented. The evaluation shows that automatic classification is possible and could be used to improve the performance of a search engine. This classifier is then extended to perform automatic metadata generation using the Resource Description Framework (RDF) and Dublin Core. A proposed RDF data model, schema and automatically generated RDF syntax are documented. Automatically generated RDF metadata describing a range of automatically classified documents is shown. The research shows that automatic classification is possible and could potentially be used to enable context sensitive browsing in automated web search engines. The classifications could also be used in generating context sensitive metadata tailored specifically for the search engine domain.
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Georgala, Kleanthi [Verfasser]. « Time-efficient link discovery for data-driven applications / Kleanthi Georgala ». Paderborn : Universitätsbibliothek, 2021. http://d-nb.info/1241667500/34.
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Горідько, Руслана Володимирівна. « Оцінка інвестиційних ризиків і методи їх врахування в інвестиційній діяльності ». Thesis, Національний авіаційний університет, 2006. http://er.nau.edu.ua/handle/NAU/10557.
Texte intégralRésumé :
Горідько Р.В. Оцінка інвестиційних ризиків і методи їх врахування в інвестиційній діяльності / Матеріали міжнародної науково - практичної конференції "Сучасні проблеми економічної безпеки в ринкових умовах":. - К.: НАУ, 2006. - С. 35-37Основна мета інвестиційної діяльності господарюючих суб’єктів полягає в збільшенні доходу від інвестиційної діяльності при мінімальному рівні ризику інвестиційних вкладень.
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Schneider, Ulrich Johannes. « Anmerkungen zur Geschichte der Gelehrsamkeit ». Akad.-Verl, 2007. https://ul.qucosa.de/id/qucosa%3A13173.
Texte intégralRésumé :
Die Erinnerungskultur schlägt um in Erinnerungskult. wenn das, was über alle Konstruktionsabsicht hinaus sich zum Wissensschatz angehäuft hat, als geplantes Produkt von Strategien, Methoden und Techniken erscheint: Unsere eigene Meisterschaft wird in die Vergangenheit projiziert. Indem wir die Gelehrten des 17. und 18. Jahrhunderts zu unseren Kollegen machen und sie in ehemaliger Lebendigkeit auferstehen lassen, unterlaufen wir das Vergessen, das sie ereilt hat, und erhoffen ein ähnliches Schicksal für uns selbst. Aber ist die Gelehrtengeschichte heute nicht im gleichen Maße Rettung eines Vergessenen wie Nachahmung desselben?
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Günther, Robert, Martin Abbrent, Thomas Schnicke et Jan Bumberger. « Vom Sensor zum Forschungsdatensatz : Automatisierte Datenflüsse am UFZ ». Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, 2019. https://slub.qucosa.de/id/qucosa%3A39015.
Texte intégralRésumé :
Hintergrund:
Am Helmholtz-Zentrum für Umweltforschung - UFZ arbeiten Forschende an Fragestellungen, die sich u.a. mit den aktuellen Veränderungen des Klimas und dessen Auswirkungen auf die Landnutzung beschäftigen. Dazu werden an verschiedenen Orten eine Vielzahl unterschiedlichster Umweltparameter mit Sensoren erfasst. Diese Daten werden kontinuierlich erhoben, um die Veränderungen möglichst in Echtzeit zu beobachten (Monitoring). Teilweise kommen pro Beobachtungsort mehrere Hunderte solcher Sensoren zum Einsatz. Die dafür eingesetzten Sensoren erfassen z.B. Bodenfeuchte, Niederschlagsmenge, Strahlungen und andere abiotische Kenngrößen. Damit die Daten (nach)nutzbar sind, müssen sie so aufbereitet und beschrieben werden, dass sie für nachfolgende Prozesse maschinen-lesbar bearbeitet werden können und in einer Form vorliegen, die eine Veröffentlichung nach den FAIR-Prinzipien ermöglicht.
Herausforderung:
Die erhobenen Messdaten müssen nicht nur gesichert werden, sondern auch auf Plausibilität geprüft, prozessiert und mit hinreichender Detailtiefe beschrieben werden, damit sie nachfolgend den Forschenden für die Beantwortung ihrer Forschungsfragen als Grundlage zur Verfügung stehen. Eine Herausforderung dabei ist, dass die Daten kontinuierlich als Datenstrom anfallen. Folglich müssen Prozesse wie die strukturierte Ablage, die Anreicherung mit Metadaten sowie Prüfung auf Fehlmessungen (sog. Qualitätssicherung) automatisiert werden. Aufgrund der Heterogenität der Sensoren (unterschiedliche Hersteller stellen Daten in unterschiedlichen Formaten zur Verfügung) muss bei diesen Prozessen auch eine Formatumwandlung erfolgen. Darüber hinaus sind je nach Messgröße und -verfahren verschiedene Methoden zur Plausibiläts- und Qualitätsprüfung anzuwenden.
Lösungsansatz:
Das Research Data Management Team des UFZ hat gemeinsam mit der IT-Abteilung einen Daten-Workflow entwickelt, der die unterschiedlichen Daten automatisch zusammenführt, sichert und nach einem vordefinierten Schema mit Metadaten anreichert.
Der Einsatz des Workflows wird exemplarisch anhand von aktuellen Forschungsprojekten vorgestellt und die darin enthaltenen Schritte detailliert beschrieben, wobei auch auf die technische Umsetzung eingegangen wird. Insbesondere werden die Komponenten zur Datenstrukturierung und semiautomatischen Qualitätssicherung vorgestellt, bei denen auch Methoden des Machine Mearning zum Einsatz kommen. Innerhalb des Workflows können die prozessierten Daten nach verschieden Verfahren aggregiert und weiterverarbeitet werden. Das geschieht u.a. über definierte Schnittstellen zu internen und externen Services (z.B. durch Bereitstellung als Sensor Observation Service (SOS) oder mittels einer API).
Fazit:
Die im Rahmen des hier vorgestellten Workflows entwickelten Prozesse und Komponenten zum automatisierten Management von Forschungsdaten bilden eine wichtige Grundlage für das Forschungsdatenmanagement am UFZ. Durch die modulare Ausgestaltung können die Komponenten an den Bedarf der Forschenden angepasst werden und sind auch für Szenarien geeignet, in denen die Messdaten nicht als Datenstrom anfallen.
Mit diesem Workflow ist die Voraussetzung geschaffen, die am UFZ erhobene Daten auch als Linked Data der wissenschaftlichen Community und anderen Stakeholdern zur Verfügung zu stellen.
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von, der Dunk Andreas. « Datenmanagementplan – Fluch oder Segen ? » SLUB Dresden, 2019. https://slub.qucosa.de/id/qucosa%3A70592.
Texte intégralRésumé :
Der Datenmanagementplan (DMP) ist die derzeit vielleicht bekannteste Manifestation des Forschungsdatenmanagements – von manchen als Segen begrüßt und von anderen als unnötige Mehrbelastung geschmäht. Der Vortrag geht kurz darauf ein, was ein DMP ist. Vor allem aber werden wir uns ansehen, wie ein DMP Forschenden die Arbeit erleichtern, die Qualität der Forschung erhöhen und das Risiko von reputationsschädigenden Datenpannen verringern kann – und warum die EU bei ihren Forschungsprojektanträgen deshalb die Erstellung eines DMP einfordert. An einigen praktischen Beispielen werden wir nachvollziehen, welche teils gravierenden Datenpannen durch einen DMP abgewendet werden können. Dazu geben wir Tipps, auf welche Intention die Fragen eines DMP, beispielsweise von der EU, abzielen. Durch den ganzen Vortrag wird sich die These ziehen, dass mehr Forschende in ihren Projekten mit einem DMP arbeiten sollten – und zwar nicht OBWOHL, sondern WEIL ihr Arbeitsalltag sich mit immer mehr administrativen Aufgaben zu füllen scheint.
Der Beitrag zur Datenmanagementplanung greift die Themen aus den vorangegangenen Präsentationen auf und schlägt die Brücke zur nachfolgenden Poster-Session und den Diskussionen an den Thementischen des World-Cafés. Als „Anschauungsobjekt“ dient dabei der Datenmanagementplan (DMP).
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Lupina, Grzegorz. « Praseodymium silicate high-k dielectrics on Si(001) ». [S.l.] : [s.n.], 2006. http://se6.kobv.de:8000/btu/volltexte/2007/42.
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Newell, David T. « The surface structure and reconstruction of SrTiO3 (001) ». Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491541.
Texte intégralRésumé :
SrTi03 is a metal oxide with a perovskite structure which can support numerous surface reconstructions. On its (001) surface more than 7 reconstructions have been reported previously and substantiated with atomic scale imaging. These reconstructions include surface structures with periodicities of (2 xl), (2 x 2), c(4 X 4), c(4 X 2), c(6 X 2), (J5 x J5) - R26.6° and (V13 x V13) - R37.7°. Each of these reconstructions can be produced in a controlled and repeatable manner simply by changing the time, temperature, and environment in which the sample is annealed. This thesis provides the most comprehensive study of the SrTi03(00l) surface to date and provides STM imaging and chemical characterisation for the majority of the surface reconstructions which have been reported, as well as the conditions required to generate each of the structures. In addition to this work, data is shown for new surface reconstructions which have not been previously reported and include structures with periodicities of (1 xl), (4 X 4), (4V2 x V2) - R45°, and c(4V2 x 2V2) - R45° It was found that upon annealing SrTi03(001) samples at increasingly higher temperatures, the first structures to form are reconstructions which have a Ti02 double layer termination. These structures have periodicities of (2 xl), c(4 x 4) and (2 x 2) and are stable at temperatures up to 950°C. Annealing SrTi03(001) samples above 950°C results in the formation of a Ti-rich adlayer with a c(4 x 4) periodicity. This c(4 x 4) ordered surface exists up to temperatures of 1250 °c and its structure is different to that of the Ti02 double layer which forms at lower temperatures. Above anneal temperatures of 1250 °c, reduction of the sample can pass a critcal stage where the SrTi03 perovskite structure is no longer stable. Phase separation occurs giving rise to TiO islands and a surface Sr adlayer with (J5 x J5) - R26.6° periodicity. Re-annealing (J5 x J5) - R26.6° reconstructed samples below the critical temperature causes the Sradlayer to oxidise becoming a SrO-(l x 1) terminated surface. For Nb doped SrTi03(001) - (J5 x J5) - R26.6° and (1 x 1) reconstructed samples, the clectonic effect of dopants can be seen in STM images as bright four point clusters. These bright clusters arise from the perturbation of surface Sr atoms due to charge transfer from Nb atoms to Ti atoms in the atomic layer immediately beneath the Sr adlayer. For SrTi03(001) samples doped with La, the dopant atoms substitute with Sr atoms and are incorporated into the surface adlayer. This incorporation of La frustrates the formation of the (J5 x J5) - R26.6° reconstruction and leads to line structures arising on the surface which are aligned with the direction of the (J5 x J5) - R26.6° structure. SrTi03 samples annealed in highly reducing conditions, achieved by annealing in low pressures of H2 gas, formed surfaces terminated by a c(4 x 2) structure. SrTi03(001) samples pre-annealed in flowing oxygen produced structures with periodicities of (4V2 x V2) - R45°, (2 x 2), (4 X 4), and c(4V2 x 2V2) - R45°. Chemical characterisation of the reconstructions observed on the surface of SrTi03 samples indicated that samples annealed under reducing conditions had surfaces that were Ti enriched, whilst samples annealed under oxidising conditions had surfaces that were Sr enriched. The experimental work undertaken would suggest that the driving force for the reconstruction of the SrTi03 surface is the amount of oxygen that is in the surface region.
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Mastin, Mark R. Benesh Gregory Allen. « An SEGF study of the Rh(001) surface ». Waco, Tex. : Baylor University, 2007. http://hdl.handle.net/2104/5076.
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Barnes, Gareth William. « Solid source MBE growth of InAs / InP(001) ». Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409582.
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Ringham, Benjamin David. « Ab-initio studies of SrTiO3(001) surface reconstructions ». Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/9844.
Texte intégralRésumé :
A number of SrTiO3(001) surface reconstructions have been studied using Plato, Package for Linear Combinations of Atomic Type Orbitals, a first principles density functional theory approach. Energy calculations have been performed for each surface reconstruction, and phase diagrams produced for a range of temperatures and pressures.
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Olavarría, Contreras Ignacio José. « Nucleación de cobre por electrodeposición sobre TIO2 [001] ». Tesis, Universidad de Chile, 2013. http://repositorio.uchile.cl/handle/2250/114079.
Texte intégralRésumé :
Magíster en Ciencias, Mención FísicaEste trabajo analiza el problema de la nucleación de cobre en el proceso de electrodepo- sición, la formación de estructuras bi y tridimensionales en la superficie de un sustrato, de manera de determinar las características del sustrato que promueven o impiden la formación de dichas estructuras. Para lograr estos objetivos se hace uso de microscopia de puntas de prueba, análisis de XPS y mediciones cronoamperométricas. Los datos se contrastan con las teorías de nucleación mediada por difusión para procesos electroquímicos. Los sustratos utilizados fueron TiO2 en su fase rutilo y dirección (001) y grafito pirolítico altamente orientado (HOPG)en dirección (0001), debido a que son sustratos planos que debie- ran permitir un buen control de los defectos superficiales, que son los principales candidatos como centros de nucleación. Gran parte del trabajo constó en la preparación y caracteriza- ción del TiO2 ya que, al ser un aislador, debió ser dopado para permitir la electrodeposición, pero a raíz de este tratamiento se evidenció una nutrida cantidad de defectos superficiales, tanto topográficos como electrónicos (estos últimos denominados puntos activos") que no se encuentran bien documentados en la literatura. Es de particular interés sobre el campo de la electrodeposición el efecto de los defectos electrónicos en la distribución de núcleos, ya que estos pueden afectar la forma en la que se distribuye el campo eléctrico y por tanto la manera en que aparecen los núcleos. Los resultados muestran una disminución de los puntos activos"luego de una electrode- posición temprana, mientras por AFM se observa la aparición de núcleos puntiagudos y una considerable disminución de la rugosidad superficial con respecto al sustrato antes del recu- brimiento. Sin embargo las curvas electroquímicas no tienen una interpretación directa en términos de las teorías disponibles para nucleación en sistemas electroquímicos.
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Leandri, Christel. « Adsorption du silicium sur l'argent (001) et (110) ». Aix-Marseille 2, 2004. http://www.theses.fr/2004AIX22042.
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Marešová, Eva. « Stabilita a řiditelnost experimentálního letounu VUT 001 Marabu ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228431.
Texte intégralRésumé :
This diploma thesis deals with a stability and manoeuvrability of experimental aircraft VUT 001 MARABU. It contains calculation of aerodynamic stability derivations and other data necessary for evaluation of static and dynamic stability. Assessment of convenient autopilot.
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Cho, Taeseung. « A rhetorical analysis of Ezekiel 37:1-14 defining the function of ruah / ». Dallas, Tex. : Dallas Theological Seminary, 2008. http://dx.doi.org/10.2986/tren.001-1200.
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Crisostomo, Christain A. « Deity portrayals and basis for discord in biblical and Mesopotamian communal laments ». Dallas, Tex. : Dallas Theological Seminary, 2008. http://dx.doi.org/10.2986/tren.001-1219.
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Kelly, Michael G. « 1 Corinthians 9:22 "all things to all men" analysis and implications for the southern Baptist Convention / ». Dallas, Tex. : Dallas Theological Seminary, 2008. http://dx.doi.org/10.2986/tren.001-1209.
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