Nesse trabalho foram fabricados filmes finos de TiO2 por RF magnetron sputtering reativo sobre substrato de silício (1 0 0). A pressão parcial do oxigênio na câmara foi variada de 5 a 100% em relação ao argônio. Após a deposição os filmes foram submetidos a tratamento térmico em atmosfera de oxigênio. A estequiometria dos filmes e o perfil de profundidade foram obtidos por RBS. A estrutura cristalina foi obtida por XRD. As propriedades ópticas foram obtidas por interferometria e reflectância e as elétricas por meio das curvas C-V. Os valores de espessura dos filmes sem tratamento térmico aumentaram aproximadamente 41% com o aumento do oxigênio na câmara de deposição. Essa variação está ligada ao aumento da eficiência do sputtering do alvo. Os índices de refração dos filmes sem tratamento térmico se mantiveram dentro de um intervalo de aproximadamente 2,3 a 2,4. A diminuição do band gap com o tratamento térmico é consequência da mudança de fase cristalográfica de anatase para rutila. A estequiometria TiOx dos filmes antes do tratamento térmico apresentaram valores de x entre 2,0 e 2,4. A espessura em TFU dos filmes aumentou com o percentual de oxigênio na câmara. As amostras que receberam tratamento térmico apresentaram difusão de titânio na interface do substrato e incorporação de oxigênio no filme. Os valores da constante dielétrica aumentaram com o percentual de oxigênio na câmara, em contraposição com o efeito do tratamento térmico que diminuiu o valor. Todos os resultados observados são coerentes do ponto de vista da mudança de fase anatase rutila e aumento do percentual de oxigênio na câmara. / In this work thin films of TiO2 were produced by reactive RF magnetron sputtering on silicon substrate (1 0 0). The oxygen partial pressure in the chamber was varied from 5 to 100% in relation to argon. After deposition the films were submitted to thermal treatment under an oxygen atmosphere. The stoichiometry of the films and the depth profile were obtained by RBS. The crystal structure was obtained by XRD. Its optical properties were obtained by interferometry and reflectance and the electrical were obtained by means of the C-V curves. The thickness values of films without heat treatment increased approximately 41% with the increase of oxygen in the deposition chamber. This variation is linked to the increased sputtering efficiency of the target. The refractive indexes of films without heat treatment remained within a range of about 2.3 to 2.4. The decrease of the band gap with the heat treatment is a consequence of the change of crystallographic phase from anatase to rutile. The TiOx stoichiometry of the films before the heat treatment showed values of x between 2.0 and 2.4. The TFU thickness of the films increased with the percentage of oxygen in the chamber. The samples that received heat treatment shows diffusion of titanium at the interface of the substrate and incorporation of oxygen in the film. The values of the dielectric constant increased with the percentage of oxygen in the chamber, as opposed to the effect of the thermal treatment that decreased the value. All the results observed are consistent from the point of view of the anatase - rutile phase transition and the increase in the oxygen percentage in the chamber.

Global warming and developments of alternative energy technologies have become important issues nowadays. Subsequently, the concept of energy harvesting is rising because of its ability of transferring waste energy into usable energy. Thermoelectric devices play a role in this field since there is tremendous waste heat existing in our lives, such as heat from engines, generators, stoves, computers, etc. Thermoelectric devices can extract the waste heat and turn them into electricity. Moreover, the reverse thermoelectric phenomenon has the function of cooling which can be applied to refrigerator or heat dissipation for electronic devices. However, the energy conversion efficiency is still low comparing to other energy technologies. The efficiency is judged by thermoelectric figure of merit (ZT), defined by Seebeck coefficient, electrical conductivity and thermal conductivity. In order to improve ZT, thin film materials are good candidates because of their structural effects on altering ZT.    Ca3Co4O9 thin films grown by reactive radio frequency magnetron sputtering followed by post-annealing process is studied in this thesis. Structural properties of the films with the evolution of elemental ratio (Ca/Co) of calcium and cobalt have been investigated. For the investigations, three samples having elemental ratio 0.82, 0.72, and 0.66 for sample CCO1, CCO2 and COO3, respectively, have been prepared. Structural properties of the films have been investigated by X-ray diffraction (XRD) θ-2θ and pole figure analyses. Surface morphology of the films has been investigated by scanning electron microscopic (SEM) analyses. The highly oriented and phase pure epitaxial Ca3Co4O9 thin films were obtained in the end.   Mixing of ScN and CrN to obtain ScxCr1-xN solid solution thin films by DC magnetron sputtering is the other task in this thesis. Growth of ScN and CrN thin films were studied first in order to get the best mixed growth conditions. The phase shifts between ScN (111) and CrN (111) peaks were observed in mixed growth films by XRD θ-2θ measurements, indicating the formation of ScxCr1-xN. Surface morphology of the films were investigated by SEM. The (111)-oriented ScxCr1-xN thin films with decent surface smoothness grown by DC magnetron sputtering at 600 °C in pure nitrogen with bias were developed.

Made available in DSpace on 2014-12-17T14:07:10Z (GMT). No. of bitstreams: 1 IgorON_DISSERT.pdf: 2261728 bytes, checksum: ec2c0dd089b3f051427a0e42ea972424 (MD5) Previous issue date: 2011-12-09 / The technique of surface coating using magnetron sputtering is one of the most widely used in the surface engineering, for its versatility in obtaining different films as well as in the micro / nanometric thickness control. Among the various process parameters, those related to the active species of the plasma are of the most fundamental importance in the mechanism and kinetics of deposition. In order to identify the active species of the plasma, parameters such as gas flow, pressure and density of electric power were varied during titanium coating on glass substrate. By flowing argon gas of 10, 20, 30, 40 and 50 sccm (cubic centimeters per minute) for each gas flow a sequential scan of the electric current of 0.10, 0.20, 0.30, 0.40 , 0.50 A. The maximum value of 0.50 A was chosen based both on literature data and on limitations of the equipment. The monitoring of plasma species present during the deposition was carried out in situ by the technique of optical emission spectroscopy (OES) through the spectrometer Ocean Optics USB2000 Series. For this purpose, an apparatus was developed to adapt the OES inside the plasma reactor to stay positioned closest to the target. The radiations emitted by the species were detected by an optical fiber placed behind the glass substrate and their intensities as a function of wavelength were, displayed on a monitor screen. The acquisition time for each condition of the plain parameters was related to the minima of spectral lines intensities due to the film formed on the substrate. The intensities of different emission lines of argon and titanium were then analyzed as a function of time, to determine the active species and estimate the thickness of the deposited films. After the deposition, the coated glasses thin films were characterized by optical transmittance through an infrared laser. It was found that the thickness and deposition rate determined by in situ analysis were consistent with the results obtained by laser transmittance / t?cnica de revestimento superficial utilizando magnetron sputtering ? uma das mais utilizadas pela engenharia de superf?cie, pela sua versatilidade na obten??o de diferentes filmes bem como no controle micro/nanom?trico de sua espessura. Dentre os v?rios par?metros do processo, aqueles relacionados com as esp?cies ativas do plasma s?o de fundamental import?ncia no mecanismo e cin?tica da deposi??o. Com o objetivo de identificar as esp?cies ativas do plasma, par?metros como fluxo de g?s, press?o de trabalho e densidade de pot?ncia el?trica foram variados durante o revestimento de tit?nio em substrato de vidro. Foi utilizado arg?nio com fluxos de 10; 20; 30; 40 e 50 sccm (cent?metro c?bico por minuto) e para cada fluxo de g?s uma varredura sequencial da corrente el?trica de 0,10; 0,20; 0,30; 0,40; 0,50A (amp?res). O valor de m?ximo de 0,50A foi escolhido com base em dados da literatura e limita??es do equipamento. O monitoramento das esp?cies do plasma presentes durante a deposi??o foi realizado "in situ", pela t?cnica de espectroscopia de emiss?o ?ptica (EEO) atrav?s do espectr?metro USB2000 Series da Ocean Optics. Para isso um aparato foi desenvolvido para adaptar o EEO dentro do reator de plasma de maneira que ficasse posicionado o mais pr?ximo poss?vel do alvo. As radia??es emitidas pelas esp?cies foram detectadas atrav?s de uma fibra ?ptica colocada por tr?s do substrato de vidro e suas intensidades, em fun??o do comprimento de onda, foram exibidas na tela de um monitor. O tempo de aquisi??o para cada condi??o de par?metro do plasma foi aquele em que a intensidade espectral deca?a para zero, devido ao filme formado no substrato. As intensidades de diferentes linhas de emiss?o de arg?nio e de tit?nio foram ent?o analisadas em fun??o do tempo, para determinar as esp?cies ativas e estimar a espessura dos filmes depositados. Ap?s a deposi??o, os filmes finos que revestiram os vidros foram caracterizados por transmit?ncia optica, atrav?s de um laser no infravermelho. Verificou-se que os valores da espessura e da taxa de deposi??o s?o determinada pela an?lise "in situ", foram coerentes com os resultados obtidos atraves da transmit?ncia por laser

Submitted by Ziani DE SOUZA SCHIABER (zianisouza@yahoo.com.br) on 2016-05-02T20:43:07Z No. of bitstreams: 1 Tese_Final_Ziani_Schiaber.pdf: 4224142 bytes, checksum: 63114f480403729da0d811c82872c3cc (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-04T19:24:06Z (GMT) No. of bitstreams: 1 schiaber_zs_dr_bauru.pdf: 4224142 bytes, checksum: 63114f480403729da0d811c82872c3cc (MD5) / Made available in DSpace on 2016-05-04T19:24:06Z (GMT). No. of bitstreams: 1 schiaber_zs_dr_bauru.pdf: 4224142 bytes, checksum: 63114f480403729da0d811c82872c3cc (MD5) Previous issue date: 2016-04-19 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Nanosestruturas de GaN destacam-se devido à baixa densidade de defeitos e consequentemente alta qualidade estrutural e óptica quando comparadas ao material em forma de filme. O entendimento dos mecanismos de formação de nanofios e nanocolunas de GaN por diferentes técnicas é fundamental do ponto de vista da ciência básica e também para o aprimoramento da fabricação de dispositivos eletrônicos e optoeletrônicos baseados nesse material. Neste trabalho discorre-se sobre a preparação e caracterização de nanofios e nanoestruturas de GaN pelas técnicas de epitaxia por magnetron sputtering e epitaxia por feixe molecular em diferentes tipos de substratos. Pela técnica de epitaxia por magnetron sputtering foram obtidos nanocristais e nanocolunas de GaN, além de uma região com camada compacta. Visando criar uma atmosfera propícia para o crescimento de nanoestruturas de GaN não coalescida, atmosfera de N2 puro e um anteparo, situado entre o alvo e o porta-substratos, foram utilizados. O anteparo causou diferença no fluxo incidente de gálio no substrato, ocasionando a formação de diferentes tipos de estruturas. A caracterização das amostras se deu principalmente através de medidas de microscopia eletrônica de varredura, difração de raios X e espectroscopia de fotoluminescência. As nanocolunas, de 220 nm de altura, foram formadas na região distante 2 mm do centro da sombra geométrica do orifício do anteparo e apresentaram orientação [001] perpendicular ao substrato, comumente encontrada em nanofios de GaN depositados por MBE. Em relação aos nanofios obtidos pela técnica de MBE, investigou-se a possibilidade de controlar a densidade de nanofios através de uma camada de Si sobre o GaN–Ga polar visando inibir a coalescência. Diferentes quantidades de Si foram depositadas e a densidade dos nanofios foi diferenciada significativamente. Os nanofios apresentaram densidade média de 108 nanofios/cm2 com 0,60 nm de espessura da camada de Si. Espessuras menores não resultaram no crescimento de nanofios, porém espessuras superiores causaram uma alta densidade de nanofios de 1010 nanofios/cm2 que permaneceu constante, independentemente do tempo de deposição. Medidas de polo por difração de raios X evidenciaram que os nanofios nuclearam-se orientados e em uma camada cristalina de Si ou SixNy. Experimentos de ataque químico com KOH indicaram a polaridade N para o nanofio e as medidas de difração por feixe convergente confirmaram a polaridade de N para o nanofio e Ga para a buffer layer. Os resultados obtidos neste trabalho permitiram um melhor entendimento da nucleação e dos mecanismos de formação de nanoestruturas de GaN, viabilizando maior controle das características dessas nanoestruturas produzidas. / GaN nanowires and nanocolumns stand out due to the low defect density and high structural and optical quality compared to the corresponding thin films. The understanding of the formation mechanism of the different GaN structures using different techniques is critical to improving the manufacture of the electronic and optoelectronic devices based on this material. This thesis focuses on the preparation and characterization of GaN nanowires and nanostructures. The molecular bem epitaxy (MBE) and magnetron sputtering epitaxy (MSE) were used and different substrates were tested. Concerning GaN nanocrystals and nanocolumns obtained by MSE, optimization of the deposition conditions was necessary in order to produce non-coalesced GaN nanostructures. The best conditions were: pure N2 atmosphere, silicon substrate, and a perforated screen placed between the target and the substrate holder. The later produced differences on the Ga flow to the substrate, inducing the formation of different structures, depending on the position of growth spot. Samples were characterized using scanning electron microscopy, X-ray diffraction and photoluminescence spectroscopy. Nanocolumns were observed, mainly in sites corresponding to a disc of radius 2 mm from the geometric centre of the hole. The columns were oriented with the GaN [001] axis perpendicular to the Si (111) substrate surface, situation which is commonly found in GaN nanowires deposited by MBE. Regarding the nanowires prepared by MBE technique, in order to inhibit coalescence and to investigate the possibility of controlling the numerical density of nanowires, we have used Si cap layers on top of the Ga-polar GaN buffer layer. Different amounts of Si have been deposited, and the density of the nanowires was significantly modified. With Si layer thickness of 0.60 nm, the nanowires had an average density of 108 nanowires/cm2 . Lower thickness did not result in the growth of nanowires, but higher thickness caused a high density of nanowires of 1010 nanowires/cm2 which remained constant regardless of the deposition time. X-ray diffraction pole figures showed that the different nanowires grown up in oriented fashion in a crystalline layer of Si or SixNy. Etching with KOH indicated N polarity for the grown nanowires, in spite of the fact that they were grown using Ga polar GaN buffer layers. Measurements by convergent beam electron diffraction confirmed the N polarity to the nanowire and Ga polarity for the buffer layer. Aspects obtained in this study allowed a better understanding of nucleation and nanostructures formation mechanisms of GaN, enabling greater control of the characteristics of these nanostructures produced. / FAPESP: 2011/22664-2 / FAPESP: 2013/25625-3

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Agradecemos a compreensão on 2018-09-26T13:33:08Z (GMT) / Submitted by Lucas Jorge Affonço (lucas_jorgeaffonco@yahoo.com.br) on 2018-09-26T13:39:25Z No. of bitstreams: 1 Dissertação_POSMAT_LucasJorgeAffonco.pdf: 1731555 bytes, checksum: 7c7c9ba43b8b832af33307bef8e74d22 (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-09-26T17:02:25Z (GMT) No. of bitstreams: 1 affonço_lj_me_bauru.pdf: 1731555 bytes, checksum: 7c7c9ba43b8b832af33307bef8e74d22 (MD5) / Made available in DSpace on 2018-09-26T17:02:25Z (GMT). No. of bitstreams: 1 affonço_lj_me_bauru.pdf: 1731555 bytes, checksum: 7c7c9ba43b8b832af33307bef8e74d22 (MD5) Previous issue date: 2018-07-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O nitreto de titâno apresenta uma vasta gama de aplicações. Entre elas destacam-se as aplicações em recobrimento de superfícies que exploram características mecânicas tais como dureza e módulo de elasticidade do material para aplicações em biomateriais. Essas características e suas correlações com a microestrutura são investigadas, nesse trabalho, em função dos parâmetros de deposição de filmes de TiN. Os filmes foram depositados pela técnica de magnetron sputtering reativo em rádio frequência, sobre substratos de titânio, de sílica, de silício e de uma liga de titânio-nióbio. Nas deposições, foi utilizado um alvo de titânio puro e misturas gasosas de argônio e nitrogênio, com diferentes fluxos de nitrogênio. As potências empregadas foram de 240 W e 300 W, com diferentes tempos de deposição. Medidas de taxa de deposição e emissão óptica do plasma auxiliaram na escolha dos parâmetros de deposição. As análises das difrações de raios X mostraram que com o aumento do fluxo de nitrogênio os cristalitos tendem a apresentar uma orientação preferencial com os planos (200) do TiN paralelos à superfície do substrato, além de indicar a presença de strain nos filmes. Medidas de nanoindentação foram realizadas nas amostras, com o intuito de obter a dureza e o módulo de elasticidade dos filmes depositados com diferentes fluxos de nitrogênio. Buscando assim determinar a influência do fluxo sobre as propriedades mecânicas e a microestrutura dos filmes. Verificou-se que a dureza nas amostras depositadas a 10 sccm foi a maior, variando de 10 a 18 GPa de acordo com a profundidade de penetração, sendo essa amostra a que apresentou maior textura de orientação favorecendo os planos (200). O módulo de elasticidade foi maior para a amostra de 8 sccm, em torno de 140 GPa, sendo essa a amostra que apresentou maior strain compressivo. Verificou-se que a técnica de sputtering reativo é versátil para o crescimento dos filmes de nitreto de titânio, e que o fluxo de nitrogênio usado nas deposições é um parâmetro de grande impacto nas características mecânicas e estruturais dos filmes obtidos. / The titanium nitride (TiN) has mechanical properties that are useful in a wide range of applications. In special, it is being investigated to improve the surfaces of bone implants. The mechanical properties of TiN films deposited by reactive magnetron sputtering and their correlations with microstructure will be investigated in this dissertation as a function of the deposition parameters. The films were deposited in titanium, silica, silicon and titanium-niobium substrates. A pure titanium target and a mix of argon and nitrogen gases were used in the depositions. The influence of the variation of the reactive gas fluxes on the mechanical properties and in the microstructure of the films were investigated, for applied powers of 240 W and 300 W at 13.6 MHz. Deposition rate and plasma optical emission measurements helped to control the deposition parameters. X ray diffraction analysis show that all films present compressive strain and, at high nitrogen fluxes, a preferred crystallite orientation of planes (200) parallel to the substrate surface occurs. Nanoidentation measurements were performed, for different nitrogen fluxes, to obtain the hardness and elastic modulus of TiN films. The hardness of films deposited at 10 sccm, varied between 10 and 18 GPa, as a function of the penetration depth, and is higher than the observed in other samples. These films also showed the higher (200) plane texture. The elastic modulus is higher on films deposited at 8 sccm N2 flow (around 140 GPa). These films also showed the higher compressive strain. It was checked that the reactive sputtering is a resourceful technique for titanium nitride deposition, and nitrogen flux present a high impact in the structure and mechanical properties of the deposited films.

Nesse trabalho foram fabricados filmes finos de TiO2 por RF magnetron sputtering reativo sobre substrato de silício (1 0 0). A pressão parcial do oxigênio na câmara foi variada de 5 a 100% em relação ao argônio. Após a deposição os filmes foram submetidos a tratamento térmico em atmosfera de oxigênio. A estequiometria dos filmes e o perfil de profundidade foram obtidos por RBS. A estrutura cristalina foi obtida por XRD. As propriedades ópticas foram obtidas por interferometria e reflectância e as elétricas por meio das curvas C-V. Os valores de espessura dos filmes sem tratamento térmico aumentaram aproximadamente 41% com o aumento do oxigênio na câmara de deposição. Essa variação está ligada ao aumento da eficiência do sputtering do alvo. Os índices de refração dos filmes sem tratamento térmico se mantiveram dentro de um intervalo de aproximadamente 2,3 a 2,4. A diminuição do band gap com o tratamento térmico é consequência da mudança de fase cristalográfica de anatase para rutila. A estequiometria TiOx dos filmes antes do tratamento térmico apresentaram valores de x entre 2,0 e 2,4. A espessura em TFU dos filmes aumentou com o percentual de oxigênio na câmara. As amostras que receberam tratamento térmico apresentaram difusão de titânio na interface do substrato e incorporação de oxigênio no filme. Os valores da constante dielétrica aumentaram com o percentual de oxigênio na câmara, em contraposição com o efeito do tratamento térmico que diminuiu o valor. Todos os resultados observados são coerentes do ponto de vista da mudança de fase anatase rutila e aumento do percentual de oxigênio na câmara. / In this work thin films of TiO2 were produced by reactive RF magnetron sputtering on silicon substrate (1 0 0). The oxygen partial pressure in the chamber was varied from 5 to 100% in relation to argon. After deposition the films were submitted to thermal treatment under an oxygen atmosphere. The stoichiometry of the films and the depth profile were obtained by RBS. The crystal structure was obtained by XRD. Its optical properties were obtained by interferometry and reflectance and the electrical were obtained by means of the C-V curves. The thickness values of films without heat treatment increased approximately 41% with the increase of oxygen in the deposition chamber. This variation is linked to the increased sputtering efficiency of the target. The refractive indexes of films without heat treatment remained within a range of about 2.3 to 2.4. The decrease of the band gap with the heat treatment is a consequence of the change of crystallographic phase from anatase to rutile. The TiOx stoichiometry of the films before the heat treatment showed values of x between 2.0 and 2.4. The TFU thickness of the films increased with the percentage of oxygen in the chamber. The samples that received heat treatment shows diffusion of titanium at the interface of the substrate and incorporation of oxygen in the film. The values of the dielectric constant increased with the percentage of oxygen in the chamber, as opposed to the effect of the thermal treatment that decreased the value. All the results observed are consistent from the point of view of the anatase - rutile phase transition and the increase in the oxygen percentage in the chamber.

Solid lubricant coatings with controlled microstructures are good candidates in providing lubricity in moving mechanical assembly applications, such as orthopedics and bearing steels. Nanocrystalline ZnO coatings with a layered wurtzite crystal structure have the potential to function as a lubricious material by its defective structure which is controlled by sputter deposition. The interrelationships between sputtered ZnO, its nanocrystalline structure and its lubricity will be discussed in this thesis. The nanocrystalline ZnO coatings were deposited on silicon substrates and Ti alloys by RF magnetron sputtering with different substrate adhesion layers, direct current biases, and temperatures. X-ray diffraction identified that the ZnO (0002) preferred orientation was necessary to achieve low sliding friction and wear along with substrate biasing. In addition, other analyses such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were utilized to study the solid lubrication mechanisms responsible for low friction and wear.

Neste trabalho foram realizadas algumas deposições de filmes de Nitreto de Titânio sobre substrato de aço inoxidável. Foi utilizado o processo conhecido como triodo magnetron sputtering. Os parâmetros de deposição foram mantidos entre as deposições, exceto pela voltagem de bias no substrato, que foi variada de uma deposição para outra. Medições in-situ das tensões residuais no filme depositado foram realizadas. As medições foram feitas através do método da curvatura do substrato, utilizando-se um sensor capacitivo posicionado dentro da câmara de deposição. Embora o dispositivo não tenha sido capaz de quantificar os valores de tensão, foi possível identificar a natureza das mesmas, indicando se elas são de caráter trativo ou compressivo. Comprovou-se a possibilidade do uso de sistemas capacitivos para medições em sputtering. Observou-se que os filmes depositados apresentaram tensões de caráter trativo durante as deposições. / In this work, a series of depositions of titanium nitride thin films was conducted in a triode unbalanced magnetron sputtering chamber. Similar parameters were selected during each deposition, except for the substrate bias voltage, which was different for every deposition. An in-situ measurement of film residual stresses was carried out as the depositions proceeded. This measurement was based on substrate curvature, which was assessed by a home-built capacitive sensor positioned inside the sputtering chamber. Although the measurement device was not able to quantify the stress values, it was possible to identify if they were tensile or compressive. It was proved the possibility of using capacitive measurement devices in sputtering processes. It was possible to observe that the films underwent tensile stresses during the deposition.

Ce travail porte sur la préparation de couches minces et sur des dispositifs flexibles à base de CoSb₃ performant et à faible coût par pulvérisation cathodique pour des applications thermoélectriques. Dans un premier temps, La pulvérisation cathodique et la co-pulvérisation ainsi que le procédé de traitement thermique ont été étudiés et optimisés pour améliorer la microstructure et surtout les propriétés thermoélectriques de couches minces. Ces deux techniques de dépôt ont donné un facteur de puissance respectivement de 1,47 × 10-4 Wm-1K-2 et de 0,98 × 10-4 Wm-1K-2. Deuxièmement, Ag et Ti ont été utilisés pour doper les couches minces de CoSb3 via un dépôt par pulvérisation magnétron. La microstructure, la morphologie, la composition et les propriétés thermoélectriques des couches minces de CoSb3 dopés ou co-dopeés sont fortement dépendantes de la teneur de dopage. Une amélioration simultanée du coefficient de Seebeck et de la conductivité électrique grâce au dopage par Ag, a été obtenue, indiquant que Ag est un dopant efficace avec un facteur de puissance maximal de 2,97 × 10-4 Wm-1K-2, plusieurs fois celui de l'échantillon non dopé. Des résultats similaires peuvent être obtenus pour des couches minces dopées au Ti, avec une amélioration simultanée du coefficient de Seebeck et de la conductivité électrique. En particulier, la conductivité thermique de la couche mince a été considérablement réduite en contrôlant soigneusement la nanostructure et la teneur en dopage Ti par optimisation du procédé de dépôt, ce qui a entraîné une augmentation de la figure de mérite ZT de 0,15 à 0,90. Troisièmement, des études détaillées sur des couches minces de CoSb₃ co-dopées Ag/(Sn, Ti ou In) ont été réalisées. L'influence de la nature et de la concentration du co-dopant sur les propriétés des couches minces de CoSb₃ a été étudiée. Le coefficient de Seebeck et la conductivité électrique de toutes les couches minces co-dopées sont simultanément augmentés par rapport à la couche mince non dopée. Le facteur de puissance a été ainsi nettement augmentée et une valeur d'environ 0,32 mWm-1K-2 a été obtenue pour des couches minces co-dopées Ag/Sn. Le facteur de puissance maximal pour des couches co-dopées Ag/Ti et Ag/In est également proche d cette valeur. De plus, une faible conductivité thermique a aussi été obtenue pour ces couches co-dopées, en particulier avec le co-dopage Ag/In, conduisant à une valeur ZT beaucoup plus élevée que les autres couches minces. Enfin, un dispositif à base de nano-couches de CoSb₃ a été fabriqué et une structure des électrodes en multicouche a été mise au point afin d'améliorer la stabilité thermique du dispositif à l'air. Une tension de sortie supérieure à 90 mV et une densité de puissance élevée de 0,46 mWcm-2 peuvent être obtenues à partir du dispositif fabriqué. De plus, ce dispositif a également été testé en tant que capteur thermique et il présente une réponse rapide, avec un temps de réaction de quelques centaines de millisecondes avec une grande stabilité. Il a été également démontré la possibilité d'obtenir une tension de sortie relativement élevée d'environ 7 V avec une intensité de courant d'environ 0,35 mA grâce à ces dispositifs thermoélectriques à couches minces. Ces résultats permettent d'envisager des applications réelles, notamment pour alimenter des équipements électroniques/électriques portatifs. / This work was focused on the preparation of low-cost and high performance CoSb₃ thin films by magnetron sputtering deposition, and on the preparation of efficient flexible thin film devices based on CoSb₃ thin films for thermoelectric application. Firstly, two methods, co-sputtering and single target sputtering, for preparing CoSb₃ thin films by using magnetron sputtering deposition were studied and the heat-treatment process was optimized for the improvement of the micro-structure and thermoelectric properties of the films. Thin films prepared by co-sputtering method or using a single alloy target deposition method have a maximum power factor value of 1.47 × 10-4 Wm-1K-2 and 0.98 × 10-4 Wm-1K-2 respectively. Secondly, Ag and Ti were used for doping the CoSb₃ thin films via magnetron sputtering deposition. The microstructure, morphology, composition, and thermoelectric properties of the single doped CoSb₃ films are found to strongly dependent on the doping content. The results demonstrate a simultaneous improvement of the Seebeck coefficient and the electrical conductivity through Ag doping, indicating that Ag is an efficient dopant for CoSb₃ thin film. Maximal power factor value of 2.97×10-4 Wm-1K-2 has been obtained after Ag doping, which is several times of the value for the un-doped sample. Similar results have been obtained from the single Ti doped CoSb₃ thin films. Interestingly, the thermal conductivity of the film has also been dramatically reduced by carefully controlling the nano-structure and Ti doping content, resulting in an enhanced ZT value from 0.15 to 0.90. Thirdly, detailed studies on magnetron sputtering deposition Ag/(Sn, Ti or In) co-doped CoSb3 thin films have been performed. The influence of the co-doped element type and content on the properties of CoSb₃ thin films has been demonstrated. The Seebeck coefficient and the electrical conductivity of all the co-doped thin films have been simultaneously increased comparing to the un-doped thin film, leading to distinctly enhanced power factor. A maximum power factor value of about 0.32 mWm-1K-2 can be obtained from Ag/Sn co-doped thin film, and similar results have been obtained also from Ag/Ti and Ag/In co-doped films. Additionally, lower thermal conductivity has been obtained from the co-doped thin films, especially with the Ag/In co-doping, leading to much higher room temperature ZT value for the co-doped films, compared to the un-doped or Ag-doped thin films. Lastly, CoSb₃ based nano thin film device has been fabricated and a multilayer structure of the electrodes was used in order to improve the thermal stability of the device in air. A relatively high output voltage of above 90 mV and a high power density of 0.46 mWcm-2 can be obtained with this device. Moreover, this device has also been tested as thermal sensor and it exhibits a fast responsivity, with a reaction time of a few hundreds of millisecond, as well as a high stability. It has also been demonstrated the possibility of obtaining relatively high output voltage of about 7 V at a current intensity of about 0.35 mA by connecting several thin film thermoelectric devices. These results are highly encouraging for achieving practical applications such as power supply for portable electronic devices and sensor.

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Zr-Hf-N and Zr-Hf thin films were deposited by reactive magnetron sputtering in order to verify the influence of small hafnium contents that are present as contaminants on zirconium deposition targets. For this purpose different hafnium contents in the films were intentionally added by varying the deposition power. The samples were characterized by X-ray diffraction (XRD), dispersive energy X-ray spectroscopy (EDS), Rutherford backscattering spectroscopy (RBS) and nanohardness analyzes. The ZrHfN thin films were deposited and had a concentration of at% Hf of 0.49; 0.56; 0.80; 1.87 and 2.70. The deposited Zr-Hf alloys exhibited hafnium contents at up to 1.21%; 1.24; 4.35; 7.94 and 11.49. The crystalline phase obtained for the nitride films had a cubic face centered structure (FCC) and was not modified by the increase in hafnium content. The alloys presented amorphous with some crystalline regions of hexagonal structure. The hardness values ranged from 21.4 to 25.1 GPa for nitrides and from 6.1 to 8.4 GPa for zirconium alloys. / Filmes finos de Zr-Hf-N e Zr-Hf foram depositados por magnetron sputtering reativo com o intuito de verificar a influência de pequenos teores de háfnio que estão presentes como contaminantes nos alvos de deposição de zircônio. Para isto foram adicionados intencionalmente diferentes teores de háfnio nos filmes através da variação da potência de deposição. As amostras foram caracterizadas por difração de raios-X (DRX), espectroscopia de raios-Xpor energia dispersiva (EDS), espectroscopia por retroespalhamento Rutherford (RBS) e análises de nanodureza. Os filmes finos de ZrHfN foram depositados e apresentaram concentração em at.% de Hf de 0,49; 0,56; 0,80; 1,87 e 2,70. As ligas Zr-Hf depositadas apresentaram teores de háfnio em at.% de 1,21; 1,24; 4,35; 7,94 e 11,49. A fase cristalina obtida para os filmes os nitretos tinha estrutura cúbica de face centrada (CFC) e não foi modificada pelo aumento do teor de háfnio. As ligas se apresentaram amorfas com algumas regiões cristalinas de estrutura hexagonal. Os valores de dureza variaram de 21,4 a 25,1 GPa para os nitretos e de 6,1 a 8,4 GPa para as ligas de zircônio. / São Cristóvão, SE