Orientador: Antonio Riul Júnior / Banca: Carlos José Leopoldo Constantino / Banca: Marcelo Nalin / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Utilizamos uma "língua eletrônica" a base de filmes ultrafinos de diferentes materiais, e medidas de espectroscopia de impedância, para analisar amostras de açúcar fornecidas pela Usina da Barra S/A, unidade UNIVALEM de valparaíso (SP). As características do açúcar na usina são geralmente determinadas pela cor ICUMSA (International Commission for Uniform Methods of Sugar Analysis) e teor de sacarose medido por luz polarizada. Nossa proposta é verificar se a "língua eletrônica" serve como ferramenta auxiliar na avaliação dos diferentes tipos de açúcar, e também açúcares similares, mas com diferentes cores IMCUSA. Ressaltamos que o fato do açúcar ser uma substância não eletrolítica dificulta grandemente esse tipo de avaliação em dispositivos semelhantes que usam outras técnicas de medidas, como potenciometria ou voltametria cíclica. Entretanto, as amostras na concentração 1mM (abaixo do limite de sensibilidade biológico = 10mM para o paladar doce) foram facilmente identificadas, conseguimos melhorar consideravelmente a resposta das medidas de impedância elétrica corrigindo o pH = 7 de todas as amostras. Verificamos através da técnica de Espectroscopia de Espalhamento Raman possíveis interações entre o filme e as soluções analisadas, obtendo resultados satisfatórios. / Abstract: An electronic tongue system based on ultra-thin films of different materials and impedance spectroscopy measurements was used in the assessment of sugar samples from Usina da Barra S/A, Univalem branch at Valparaíso (SP). Sugar characteristics in the plant station are generally made by ICUMSA (International Commission for Uniform Methods of Sugar Analysis) colour and sucrose content, measured by polarized light. We intend to check if the electronic tongue serves as an auxiliary tool in the evaluation of different samples and also sugars having similar ICUMSA colours. It is worth mentioning that sugar is a non-electrolyte substance, being quite difficult to be detected in similar devices using other techniques, such as potentiometry and cyclic voltammetry. However, samples at 1 mM (below the human threshold = 10mM for sweetnes) were easily distinguished. We could improve considerably the correlation of the samples at pH = 7. In addition, through raman spectroscopy we check possible interactions between films and analytes, with satisfactory results. / Mestre

Orientador: Jose Alexandre Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e Computação / Made available in DSpace on 2018-09-11T21:11:59Z (GMT). No. of bitstreams: 1 Miyoshi_Juliana_M.pdf: 3791020 bytes, checksum: 460cf8c5054332b38c548b87723e8179 (MD5) Previous issue date: 2008 / Resumo: Filmes isolantes com alta constante dielétrica (high k) para a próxima geração (tecnologia CMOS de 32 nm), tais como óxido de titânio (TiOx), oxinitreto de titânio (TiOxNy), oxinitreto de titânio alumínio (AlxTiwOyNz), nitreto de titânio alumínio (AlxTiwNz) e óxido de titânio alumínio (AlxTiwOy) foram obtidos por evaporação por feixe de elétrons de Ti ou TiAl, com adicional nitretação ou oxinitretação ou oxidação por plasma ECR (Electron Cyclotron Resonance) em substratos de Si. Os filmes foram caracterizados por elipsometria (espessura), espectroscopia de emissão do infravermelho (FTIR) (ligações químicas) e microscopia de força atômica (AFM) (rugosidade da superfície). Os plasmas ECR foram caracterizados por espectroscopia por emissão óptica (OES). Estes filmes foram usados como isolantes de porta em capacitores MOS, que foram fabricados com eletrodos de Al e TiAl. Estes capacitores foram utilizados para a obtenção das medidas de capacitância - tensão (C-V) e corrente - tensão (I-V). Um valor relativo para a constante dielétrica de 3,9 foi adotado para extrair o valor de EOT dos filmes, a partir das medidas C-V sob região de forte acumulação, resultando em valores entre 1,1 nm e 1,5 nm, e densidades de carga efetiva em torno de 1012 cm-2. Das medidas I-V, foram extraídas valores de correntes de fuga através do dielétrico de porta entre 0,02 mA e 20 mA. Os melhores resultados (com correntes de fuga menores que 4 mA e EOT menores que 1,5 nm) foram obtidos pelas estruturas MOS com dielétrico de porta de AlxTiwOy e AlxTiwOyNz. Devido a estes resultados, nMOSFETs com eletrodo de Al e dielétrico de porta de AlxTiwOyNz foram fabricados e caracterizados por curvas características I-V. Foram obtidas características elétricas do nMOSFET, tais como transcondutância de 380 µS e slope de 360 mV/dec. Estes resultados indicam que os filmes AlxTiwOy e AlxTiwOyNz são adequados para a próxima geração de dispositivos (MOS). / Abstract: High k insulators for the next generation (sub-32 nm CMOS (complementary metaloxide-semiconductor) technology), such as titanium oxide (TiOx), titanium oxynitride (TiOxNy), titanium-aluminum oxynitride (AlxTiwOyNz), titanium-aluminum nitride (AlxTiwNz) and titanium-aluminum oxide (AlxTiwOy), have been obtained by Ti or Ti/Al e-beam evaporation, with additional electron cyclotron resonance (ECR) plasma nitridation or oxynitridation or oxidation on Si substrates. The films were characterized by ellipsometry (thickness), Fourier Transformed Infra Red (FTIR) (chemical bonds) and Atomic Force Microscopy (AFM) (surface roughness). The ECR plasmas were characterized by optical emission spectroscopy (OES). These films have been used as gate insulators in MOS capacitors, which were fabricated with Al or TiAl gate electrodes. These capacitors were used to obtain capacitance-voltage (C-V) and current-voltage (I-V) measurements. A relative dielectric constant of 3.9 was adopted to extract the Equivalent Oxide Thickness (EOT) of films from C-V curves under strong accumulation condition, resulting in values between 1.1 and 1.5 nm, and the effective charge densities of about 1012 cm-2. From I-V measurements, gate leakage currents through these gate dielectrics between 0,02 mA and 20 mA were extracted. The best results (leakage current lower than 4 mA and EOT thinner than 1.5 nm) were obtained by MOS structures with gate dielectrics of AlxTiwOy and AlxTiwOyNz. Because of these results, nMOSFETs with Al gate electrode and AlxTiwOyNz gate dielectric were fabricated and characterized by I-V characteristic curves. nMOSFET electrical characteristics, such as transconductance of 380 µS and sub-threshold slope of 360 mV/dec, were obtained. These results indicate that the obtained AlxTiwOyNz and AlxTiwOy films are suitable gate insulators for the next generation (MOS) devices. / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-24Bitstream added on 2014-06-13T19:29:33Z : No. of bitstreams: 1 steluti_wmdmf_me_bauru_prot.pdf: 1404257 bytes, checksum: d4e77186a5e03cec102f5d2fa890c6a8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Utilizamos uma língua eletrônica a base de filmes ultrafinos de diferentes materiais, e medidas de espectroscopia de impedância, para analisar amostras de açúcar fornecidas pela Usina da Barra S/A, unidade UNIVALEM de valparaíso (SP). As características do açúcar na usina são geralmente determinadas pela cor ICUMSA (International Commission for Uniform Methods of Sugar Analysis) e teor de sacarose medido por luz polarizada. Nossa proposta é verificar se a língua eletrônica serve como ferramenta auxiliar na avaliação dos diferentes tipos de açúcar, e também açúcares similares, mas com diferentes cores IMCUSA. Ressaltamos que o fato do açúcar ser uma substância não eletrolítica dificulta grandemente esse tipo de avaliação em dispositivos semelhantes que usam outras técnicas de medidas, como potenciometria ou voltametria cíclica. Entretanto, as amostras na concentração 1mM (abaixo do limite de sensibilidade biológico = 10mM para o paladar doce) foram facilmente identificadas, conseguimos melhorar consideravelmente a resposta das medidas de impedância elétrica corrigindo o pH = 7 de todas as amostras. Verificamos através da técnica de Espectroscopia de Espalhamento Raman possíveis interações entre o filme e as soluções analisadas, obtendo resultados satisfatórios. / An electronic tongue system based on ultra-thin films of different materials and impedance spectroscopy measurements was used in the assessment of sugar samples from Usina da Barra S/A, Univalem branch at Valparaíso (SP). Sugar characteristics in the plant station are generally made by ICUMSA (International Commission for Uniform Methods of Sugar Analysis) colour and sucrose content, measured by polarized light. We intend to check if the electronic tongue serves as an auxiliary tool in the evaluation of different samples and also sugars having similar ICUMSA colours. It is worth mentioning that sugar is a non-electrolyte substance, being quite difficult to be detected in similar devices using other techniques, such as potentiometry and cyclic voltammetry. However, samples at 1 mM (below the human threshold = 10mM for sweetnes) were easily distinguished. We could improve considerably the correlation of the samples at pH = 7. In addition, through raman spectroscopy we check possible interactions between films and analytes, with satisfactory results.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-29Bitstream added on 2014-06-13T18:50:35Z : No. of bitstreams: 1 garcia_mpb_me_bauru.pdf: 798270 bytes, checksum: 437454937b48d54f9757294afd0b12e5 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho pesquisamos variações das propriedades elétricas de filmes ultrafinos de diferentes materiais, utilizados como unidades sensoriais de uma língua eletrônica, simulando os resultados obtidos em diferentes paladares com um modelo de circuito elétrico equivalente, visando uma melhor compreensão do mecanismo de transdução envolvido. Foram utilizados filmes ultrafinos de quitosana, ftalocianina, polipirrol e perileno, que serviram de elementos transdutores do dispositivo, similar às papilas gustativas na língua humana, pois a diferença de resposta entre eles pode ser utilizada como uma impressão digital dos líquidos analisados. Esses materiais foram depositados sobre lâminas de quartzo e eletrodos interdigitados através das técnicas Langmuir-Blodgett (LB), automontagem e evaporação a vácuo. Inicialmente o trabalho foi na fabricação de filmes ultrafinos para familiarização das técnicas e equipamentos de medidas. Pôde-se verificar boa adesão dos materiais depositados sobre os eletrodos interdigitados mesmo após excessivas lavagens em água Milli-Q, permitindo sua reutilização na língua eletrônica. Os eletrodos cobertos com filmes ultrafinos foram imersos em soluções 1 mM e 1μM ácidas, salgadas, doces, amargas e umami utilizando medida de impedância elétria e um modelo de circuito elétrico equivalente já existente na literatura. Analisamos a sensibilidade de resposta a uma temperatura de aproximadamente '20 GRAUS', avaliando como os parâmetros envolvidos no circuito elétrico equivalente variam de acordo com o tipo de solução analisada, nas concentrações 1 mM e 1μM, e ainda como esses parâmetros são afetados em um mesmo material na presença de diferentes analitos. Os resultados obtidos foram também analisados pelo método estatístico de Análise de Componentes Principais (PCA, do inglês Principal Component Analysis) e Espectroscopia Raman. / In this work we study variations in the electrical properties of ultra-thin films of different materials, used as individual sensing units in an electronic tongue, simulating the results obtained in distinct tastants with an equivalent electric circuit, envisaging a better comprehension of the transducing mechanism involved. Ultra-thin films of chitosan, copper phtalocyanine, polypyrrole and perylene were used as transducers in the device, similar to the gustative papilae in the human tongue, as their electrical differences can be used as a fingerprint of the liquids analysed. The materials were deposited onto quartz plates and interdigitated electrodes through Langmuir-Blodgett (LB), layer-by-layer and vacuum evaporation techniques. Initially, we start the fabrication of the ultra-thin films to a better familiarization with equipments and tecniques. There was a good adhesion of the deposited films onto the interdigitated electrodes, even after excessive washings in Milli-Q water, allowing the re-use of the eletronic tongue system. The electrodes covered with ultra-thin films were have been soaked in 1mM and 1μM solutions of acidic, sweet, sour and bitter substances, using impedance spectroscopy as the measured technique and an equivalent circuit model already existent in the literature. The sensitivity of response at '20 GRAUS' was evaluated investigating seeking of how the involved parameters in the equivalent electric circuit varied according to the sort of solution analysed at mM and μM concentrations, and how they are affected by each material due to the presence of distinct analytes. The obtained results were also analysed by Principal Component Analysis and Raman Spectroscopy.

Orientador: Antonio Riul Júnior / Banca: Carlos José Leopoldo Constantino / Banca: Nilson Cristino da Cruz / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Neste trabalho pesquisamos variações das propriedades elétricas de filmes ultrafinos de diferentes materiais, utilizados como unidades sensoriais de uma "língua eletrônica", simulando os resultados obtidos em diferentes paladares com um modelo de circuito elétrico equivalente, visando uma melhor compreensão do mecanismo de transdução envolvido. Foram utilizados filmes ultrafinos de quitosana, ftalocianina, polipirrol e perileno, que serviram de elementos transdutores do dispositivo, similar às papilas gustativas na língua humana, pois a diferença de resposta entre eles pode ser utilizada como uma impressão digital dos líquidos analisados. Esses materiais foram depositados sobre lâminas de quartzo e eletrodos interdigitados através das técnicas Langmuir-Blodgett (LB), automontagem e evaporação a vácuo. Inicialmente o trabalho foi na fabricação de filmes ultrafinos para familiarização das técnicas e equipamentos de medidas. Pôde-se verificar boa adesão dos materiais depositados sobre os eletrodos interdigitados mesmo após excessivas lavagens em água Milli-Q, permitindo sua reutilização na "língua eletrônica". Os eletrodos cobertos com filmes ultrafinos foram imersos em soluções 1 mM e 1μM ácidas, salgadas, doces, amargas e umami utilizando medida de impedância elétria e um modelo de circuito elétrico equivalente já existente na literatura. Analisamos a sensibilidade de resposta a uma temperatura de aproximadamente '20 GRAUS', avaliando como os parâmetros envolvidos no circuito elétrico equivalente variam de acordo com o tipo de solução analisada, nas concentrações 1 mM e 1μM, e ainda como esses parâmetros são afetados em um mesmo material na presença de diferentes analitos. Os resultados obtidos foram também analisados pelo método estatístico de Análise de Componentes Principais (PCA, do inglês "Principal Component Analysis") e Espectroscopia Raman. / Abstract: In this work we study variations in the electrical properties of ultra-thin films of different materials, used as individual sensing units in an "electronic tongue", simulating the results obtained in distinct tastants with an equivalent electric circuit, envisaging a better comprehension of the transducing mechanism involved. Ultra-thin films of chitosan, copper phtalocyanine, polypyrrole and perylene were used as transducers in the device, similar to the gustative papilae in the human tongue, as their electrical differences can be used as a fingerprint of the liquids analysed. The materials were deposited onto quartz plates and interdigitated electrodes through Langmuir-Blodgett (LB), layer-by-layer and vacuum evaporation techniques. Initially, we start the fabrication of the ultra-thin films to a better familiarization with equipments and tecniques. There was a good adhesion of the deposited films onto the interdigitated electrodes, even after excessive washings in Milli-Q water, allowing the re-use of the "eletronic tongue" system. The electrodes covered with ultra-thin films were have been soaked in 1mM and 1μM solutions of acidic, sweet, sour and bitter substances, using impedance spectroscopy as the measured technique and an equivalent circuit model already existent in the literature. The sensitivity of response at '20 GRAUS' was evaluated investigating seeking of how the involved parameters in the equivalent electric circuit varied according to the sort of solution analysed at mM and μM concentrations, and how they are affected by each material due to the presence of distinct analytes. The obtained results were also analysed by Principal Component Analysis and Raman Spectroscopy. / Mestre

Orientador: Abner de Siervo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-16T08:29:21Z (GMT). No. of bitstreams: 1 Lussani_FernandoCesar1985-_M.pdf: 10633607 bytes, checksum: 81211aec04bbbd3665a1c673e003a714 (MD5) Previous issue date: 2010 / Resumo: Algumas evidências na literatura apontam para um possível ordenamento ferromagnético do Paládio. Na natureza, o Paládio é um metal de transição não ferromagnético. Filmes ultrafinos podem induzir ordenamento ferromagnético devido a diferenças nos parâmetros de rede entre o filme(Pd) e o substrato que o suporta. Neste trabalho, cresceram-se filmes ultrafinos de Paládio sobre o substrato de W(100). Para tanto, o substrato foi limpo por meio de tratamento térmico e bom- bardeamento de íons. Filmes de Paládio foram crescidos usando epitaxia por feixe atômico e obteve-se um filme com espessura de cinco monocamadas de Paládio. Esse filme foi caracterizado pelas técnicas de espectroscopia de fotoemissão e espalhamento de elétrons de baixa energia. Determinou-se a estrutura de superfície por meio da técnica de difração de fotoelétrons usando radiação síncroton (LNLS), oriunda da linha SXS, com energia do fóton de 1810 eV. Realizou-se o mesmo estudo para filmes de Paládio sobre substrato de Nb(100). Neste sistema, depositou-se Paládio sobre uma superfície reconstruída de NbO(3 x 1) - 2D. Caracterizou-se este filme e o arranjo estrutural foi obtido por meio da técnica de difração de fotoelétrons com fótons de raio-X AI Ka de energia 1486.6 eV. Em seguida calculamos, por meio da teoria do funcional da densidade, propriedades estruturais e eletrônicas do Páladio. A partir destes cálculos, os resultados encontrados na determinação estrutural foram analisados. Calculou-se a densidade de estados para alguns modelos de empacotamento e discutiu-se sobre a existência ou não de ordenamento ferromagnético nesses sistemas / Abstract: Some evidence in the literature suggest a possible ferromagnetic ordering of the Palladium. In nature, the Palladium is a non-ferromagnetic metal transition. Ultra- thin films can induce ferromagnetic ordering due to differences in lattice parameters between the film(Palladium) and the substrate that supports it. In this work, it has been grown Palladium ultrathin films on the substrate W(100). First, The substrate was cleaned by heat treatment and ion bombardment. Palladium films were grown using atomic beam epitaxy and it was obtained a film with a thickness of tive monolayers of Palladium. This film was characterized by X- ray photoelectron spectroscopy and by low energy electron diffraction. The surface structure has been determined by X-ray photoelectron diffraction technique using synchrotron radiation (LNLS), from SXS line with the photon energy of 1810 eV. We performed the same study for Palladium films over Nb(100). In this system, Palladium monolayers were deposited on a reconstructed surface of NbO(3 x 1)- 2D. These films has been characterized and the structural arrangement was achieved through the technique of photoelectron diffraction with photons from a AI Ka source with energy of 1486.6 eV. Then, it was calculated by density functional theory, the electronic and structural properties of Palladium. From these calculations, the results found in structural determination were analyzed. It has been calculated the density of states for some models of packaging and it was argued about the existence of ferromagnetic ordering in these systems / Mestrado / Física da Matéria Condensada / Mestre em Física

The broad theme of the present research investigation is on the preparation and characterization of the ultra thin films. The emerging field of nano science and technology demands the realization of different materials in nanometer dimension and a comprehensive understanding of their novel properties. Especially, the properties of the semiconducting materials in the nano dimensions are quite different from their bulk phase. A phase transition from semimetalic to semiconducting nature occurs at a thickness < 5nm of Sb ultra thin films. These facts emphasize the need for preparing these materials as nano layers and studying their properties as a function their size. Among the various characterization methods available to study the structure and the interfaces, Raman spectroscopy has proved to be a useful technique. In addition to revealing the structural information, Raman spectroscopy can bring out the quantum size effects in the lattice vibrational spectra of lower dimensional solids, stress state of the film in the initial growth stages, chemical nature of materials etc. Raman spectroscopy studies on the quantum structure of Ge and Sb are limited. This is attributed to the two serious limitations of the conventional backscattering of Raman signal. 1. The back scattered Raman signal intensity from the ultra thin layer could be below the detection limit. 2. The lower penetration depth of the lasers could inhibit the information from the buried layers. These limitations could be overcome to a major extent by employing an optical interference technique called IERS. This is basically an anti-reflection structure consisting minimum of three layers. These three layers are essential for achieving the interference conditions. The thicknesses of each layer were calculated using a matrix method. IERS structure consists of 1. A reflecting layer at the bottom of the stack (Platinum or Aluminum) 2. The second layer which is grown above the reflecting layer is a transparent dielectric layer, which introduces the necessary phase shift and hence it is called phase layer.(SiO2 or CeO2) 3. The top ultra thin layer which is to be investigated (Ge or Sb), is grown over the dielectric film and it is the layer which absorbs the most of the incident exciting light and it is called the absorbing layer. In this trilayer structure the thickness of the phase layer and the absorbing layer are adjusted in such a way that the light reflected from the air-ultra thin layer interface and the dielectric-reflector interface are equal in amplitude but opposite in phase. This leads to the destructive interference and a perfect anti-reflection condition is achieved. This enhances the near surface local field and results in the enhanced Raman signal. Regarding the reflection layer, thermally evaporated Al films were used. But the surface studies revealed a large surface roughness of 2.7nm for area of 2 µm×2µm. Also Al is known to react with oxygen and formation of an oxide layer is favored. In an effort to overcome these problems, a platinum layer was chosen instead of Al as a reflecting layer. Dual ion beam sputter deposition was employed to prepare the platinum films and to study the surface property of the films prepared at different secondary ion current density. Thus the process parameters to get the Pt film with the required surface properties were optimized. To prepare the required phase layer, optical thin films of Ceria were used. The optical and structural property of ceria is found to be sensitive to the process parameters. Hence a new deposition technique for preparing the CeO2 thin films was adopted. This technique is called Dual ion beam Sputter Deposition (DIBSD). This technique involves, two ion sources (Kaufman type). One source is used to sputter the target, which is called the primary ion source and the other one is used to assist the growing film, which is called the secondary ion source. Both argon and oxygen were fed into the secondary ion source and oxygen ions in the mixture of the gases (Ar +O2) react with the growing film and the oxygen stoichiometry in the film is maintained. Also the secondary ion bombardment of the growing film helps in the densification and it leads to the increase in the refractive index of the ceria films. The films were found to grow with a preferential orientation along (111) direction. The optical properties of the films were studied by using the transmission spectra of the films from the spectrophotometer. Powder X-Ray diffraction, and Raman spectroscopy, were employed to study the structural properties. Atomic Force Microscopy was used to examine the surface topography and to estimate the surface statistics. A stress free ceria film with a high refractive index of 2.36 at 600nm was prepared for a secondary ion beam current density of 150µA/cm2 and a beam energy of 150 eV. Raman spectra and X-ray diffraction data of these films have revealed the formation of point defects in these films as a function of secondary ion current density. Germanium (Ge) ultra thin layers were prepared by using Ion Beam Sputter Deposition (IBSD) as this technique has a good control over the rate of deposition apart from various other advantages. The Ge ultra thin films were prepared on the multilayer stacks with Al or Pt as a reflecting layer. The germanium films were prepared for the various thicknesses ranging from 1-10 nm. These films were prepared on the multilayer stack of reflecting layer and phase layer. The films were prepared for the different substrate temperatures from 40 °C to 300 °C. The films thus prepared have been analyzed by Interference Enhanced Raman Spectroscopy (IERS) for the structural and quantum size effects, by RBS for the thickness and to study interface diffusion, and Atomic Force Microscopy (AFM) for the analysis of nano structure of the grown films and also for the surface statistics. The thickness of the Ge films was found to be same as that had been calculated from the rate of deposition of the films. The films showed increase in the grain sizes with increase in the thickness of the films. The nanostructure of the films from AFM images confirms this observation. IERS of the films shows the transition from the compressive to stress free nature of the film for the nominal thickness of 1 & 2 nm. The quantum size effects of the films show the asymmetric broadening and peak shift and these observations were studied using the spatial correlation model. The TEM studies on the samples with Pt as a reflecting layer show influence of the underlying layer of CeO2 by the formation Moiré fringes. Antimony (Sb) films were prepared for the different thicknesses (3-10nm) and at different substrate temperatures (40 °C - 200 °C) on the Pt/CeO2 multilayer stacks as the absorbing layer. IERS studies on the films were performed and the results are as follows. Sb films show crystallization with increase in thickness from 3nm to 4nm. The films show amorphous to crystalline transition for the substrate temperature of 200 °C. Quantum size effects on the samples due to the phonon confinement were analyzed by the spatial correlation model. The atomic force microscopic measurements for the nanostructural information on the samples showed that the grain sizes of the films increase with increase in the thickness. Also the surface morphology shows a definite change in the features for the transition of amorphous to crystallization phase. Chapter 1 introduces the importance of Ge and Sb in the present day technologies. The current state of research on these two materials has been discussed. The importance of ceria and Pt films has been highlighted in the context of IERS and for the applications elsewhere. The advantages and disadvantages of ion beam sputter deposition have been described. The importance of Raman spectroscopy as a characterization tool for the nano structures has been shown in this chapter along with an introduction on Raman spectroscopy. Also, the importance of the other complimentary characterization techniques has been discussed. Chapter 2 presents the experimental details used to deposit and characterize the thin films. Details of IBSD and DIBSD processes are given. The characterization pertaining to structural, surface, optical and compositional properties are dealt in detail. Method to compute the optical constants of a transparent film is also given. Chapter 3 presents the properties of reflecting layers. Structural, surface and the compositional (presence of Ar ion) properties of the DIBSD platinum thin films are presented. Chapter 4 presents the optical, structural and surface properties of DIBSD ceria thin films as a function of process parameters. Chapter 5 deals with the growth and Raman analysis of ultra thin Ge films with Al and Pt as reflecting layers. Chapter 6 deals with the growth and Raman analysis of ultra thin Sb films. Chapter 7 gives the summary of the thesis and the future scope of the work.

Orientadores: Richard Landers, Abner de Siervo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin. / Made available in DSpace on 2018-08-12T18:57:37Z (GMT). No. of bitstreams: 1 Carazzolle_MarceloFalsarella_M.pdf: 9436583 bytes, checksum: 076451d27442a919e962e5f6cf59ba6a (MD5) Previous issue date: 2005 / Resumo: Neste trabalho foi estudado o crescimento de filmes ultra-finos de Sb sobre Ni(111) e In sobre Ni(111), no regime de frações de monocamadas, com o interesse no entendimento da estrutura cristalográfica e eletrônica destas ligas de superfície. Os filmes foram preparadas em ambiente de UHV e caracterizados do ponto de vista da estrutura eletrônica através da técnica experimental de espectroscopia de elétrons (XPS) e cálculos de teoria do funcional da densidade (DFT). Na determinação da estrutura cristalográfica das ligas de superfície foram utilizados LEED-qualitativo e PED (difração de fotoelétrons) e DFT. Os filmes de Sb sobre Ni(111) formaram uma liga substitucional de superfície ordenada na estrutura (Ö 3 x Ö 3) R30 °, seguindo o empacotamento fcc do substrato. Os filmes de In sobre Ni(111) formaram duas fases ordenadas, 2 x 2 e (Ö 3 x Ö 3) R30 ° e , coexistindo na superfície em forma de domínios, ambas as fases formaram ligas substitucionais seguindo o empacotamento fcc do substrato. A estrutura eletrônica do filmes foram estudadas por XPS e interpretadas com a ajuda das simulações de DFT. Em ambos os filmes não houve tranferência de cargas entre os átomos, mas tivemos evidências de uma redistribuição de cargas intra-atômica nos átomos do substrato. / Abstract: In this thesis we present a studied the growth of the ultra-thin films of Sb on Ni(111) and In on Ni(111), in the sub-monolayer regime. The main interest was on the understanding of the crystallography and electronic structure theses surface alloys. The films were grown under UHV conditions and characterized as to their electronic structure by X-ray Photoelectron Spectroscopy (XPS) and simulated theoretically by density functional theory (DFT). To determine the crystallography structure, LEED and photoelectron diffraction (PED) was used. The Sb on Ni(111) films after annealing stabilized as a substitution surface alloy in the ( Ö 3 x Ö 3 ) R 30 ° structure following the fcc substrate. The In on Ni(111) films formed two ordered phases 2x2 and (Ö 3 x Ö 3) R30 ° coexisting on the surface, both the phases formed substitution alloys following the fcc substrate. The electronic structure of both the films didn¿t show evidence of charge transfer between the atoms, but of a possible charge redistribution between the states of the Ni atoms in contact with the evaporated film. / Mestrado / Superfícies e Interfaces ; Peliculas e Filamentos / Mestre em Física

Modification of the properties of solid state structures, used for gas sensing is important task in making detection and measurement systems of volatile chemical compounds. These properties depend on material, inner structure and interaction with gas atmosphere. In hybrid materials (solid-biomolecular) biochemical recognition plays important role in gas sensing mechanism. In this work the methodologies of the SPM was applied for characterization of the local point and local area properties in the gas sensitive MO films with the nanoscaled thickness that can be used for nanosystems and hybrid materials in novel types of chemical detectors. In this dissertation morphology and physical properties of metal oxide films with thickness from a few to about 50 nm was investigated and described a relationship between the gas response and film thickness. It was experimentally shown that effects of external influence on the properties of the surface nanostructures can be described by the specific characteristics of the scanning probe spectroscopy displaying the dependences of the probe contact electric current on both the probe potential and the probe pressing force. An original method based on the SPM probe controlled electrical current was proposed for the formation of nanosystems with various electrical properties on the surfaces of thin MO films. / Kryptingas kietojo kūno darinių, naudojamų išorinio dujų poveikio detekcijai, savybių keitimas yra vienas iš aktualiausių uždavinių, sprendžiamų kuriant lakiųjų cheminių junginių poveikio atpažinimo ir matavimo sistemas. Šias savybes lemia darinių medžiaga, jų struktūra bei sąveikos su dujine aplinka ypatumai, kurie hibridiniuose dariniuose iš kietojo kūno ir biomolekulių gali būti lemiami dar ir biocheminiu atpažinimu. Šiame darbe tiriami dujoms jautrūs hibridiniai dariniai ir nanosistemos, integruotos metalo oksido plėvelėse, Skenuojančio zondo mikroskopijos (SZM) metodais. Disertacijoje susieti itin plonų (<30-50 nm) SnOx sluoksnių varžos atsako į dujas bei elektrinių savybių ypatumai su sluoksnių morfologija, priklausančia nuo auginimo sąlygų ir trukmės. Eksperimentiškai įrodyta, jog SZM lokalinių srovių tyrimai, priklausomai nuo matavimo parametrų, leidžia atskirai aprašyti technologiškai keičiamas dujoms jautrių darinių charakteristikas ir tik nanosistemose vykstančius procesus, kurie, kai kuriais atvejais, gali būti stebimi ir tipiškuose dujoms jautrių darinių taikymuose. Sukurtas originalus metodas, tinkantis nanostruktūroms metalo oksidų paviršiuje formuoti bei tų struktūrų elektrinėms savybėms keisti. Skirtingai nuo literatūroje žinomo paviršiaus nanooksidinimo, pritaikyto formuoti cheminiam poveikiui atsparias dangas, mūsų metodas leidžia formuoti įvairaus elektrinio laidumo nanostruktūras metalo oksidų paviršiuje.

Kryptingas kietojo kūno darinių, naudojamų išorinio dujų poveikio detekcijai, savybių keitimas yra vienas iš aktualiausių uždavinių, sprendžiamų kuriant lakiųjų cheminių junginių poveikio atpažinimo ir matavimo sistemas. Šias savybes lemia darinių medžiaga, jų struktūra bei sąveikos su dujine aplinka ypatumai, kurie hibridiniuose dariniuose iš kietojo kūno ir biomolekulių gali būti lemiami dar ir biocheminiu atpažinimu. Šiame darbe tiriami dujoms jautrūs hibridiniai dariniai ir nanosistemos, integruotos metalo oksido plėvelėse, Skenuojančio zondo mikroskopijos (SZM) metodais. Disertacijoje susieti itin plonų (< 30-50 nm) SnOx sluoksnių varžos atsako į dujas bei elektrinių savybių ypatumai su sluoksnių morfologija, priklausančia nuo auginimo sąlygų ir trukmės. Eksperimentiškai įrodyta, jog SZM lokalinių srovių tyrimai, priklausomai nuo matavimo parametrų, leidžia atskirai aprašyti technologiškai keičiamas dujoms jautrių darinių charakteristikas ir tik nanosistemose vykstančius procesus, kurie, kai kuriais atvejais, gali būti stebimi ir tipiškuose dujoms jautrių darinių taikymuose. Sukurtas originalus metodas, tinkantis nanostruktūroms metalo oksidų paviršiuje formuoti bei tų struktūrų elektrinėms savybėms keisti. Skirtingai nuo literatūroje žinomo paviršiaus nanooksidinimo, pritaikyto formuoti cheminiam poveikiui atsparias dangas, mūsų metodas leidžia formuoti įvairaus elektrinio laidumo nanostruktūras metalo oksidų paviršiuje. / Modification of the properties of solid state structures, used for gas sensing is important task in making detection and measurement systems of volatile chemical compounds. These properties depend on material, inner structure and interaction with gas atmosphere. In hybrid materials (solid-biomolecular) biochemical recognition plays important role in gas sensing mechanism. In this work the methodologies of the SPM was applied for characterization of the local point and local area properties in the gas sensitive MO films with the nanoscaled thickness that can be used for nanosystems and hybrid materials in novel types of chemical detectors. In this dissertation morphology and physical properties of metal oxide films with thickness from a few to about 50 nm was investigated and described a relationship between the gas response and film thickness. It was experimentally shown that effects of external influence on the properties of the surface nanostructures can be described by the specific characteristics of the scanning probe spectroscopy displaying the dependences of the probe contact electric current on both the probe potential and the probe pressing force. An original method based on the SPM probe controlled electrical current was proposed for the formation of nanosystems with various electrical properties on the surfaces of thin MO films.