Neste trabalho, foram caracterizados eletricamente capacitores MOS com alumina (Al2O3) e aluminato de háfnio (AlxHf1-xOy) como dielétricos de porta, além disso, estes filmes dielétricos foram caracterizados fisicamente. A alumina foi obtida da oxidação anódica de filmes de alumínio evaporados sobre p-Si (100) através de imersão em ácido nítrico por 4 ou 6 min, para diferentes etapas de limpeza finais do substrato: solução diluída de ácido fluorídrico (DHF) ou solução de peróxido sulfúrico (SPM). Análises de retroespalhamento de Rutherford (RBS), espectroscopia por dispersão em energia (EDS) e espectroscopia por dispersão de comprimento de onda (WDS) indicam a formação da alumina estequiométrica, sendo que a difração de raios-X (XRD), mostrou o caráter amorfo do dielétrico. Por intermédio de curvas capacitância x tensão (CV) foram obtidas a espessura equivalente ao óxido de silício (EOT2,8nm), a densidade de estados de interface (Dit1,4x1011ev-1cm-2) e a permissividade elétrica da alumina (high-k10,6). A admitância associada à corrente de fuga em capacitores MOS foi modelada através de emissão por Frenkel-Poole, tunelamento por Fowler-Nordheim e/ou corrente de fuga constante. Os aluminatos de háfnio (AlxHf1-xOy) foram obtidos sobre p-Si (100), através de deposição atômica por camadas (ALD) para diferentes proporções molares de háfnio (25, 50 ou 75%) e para diferentes tratamentos posteriores (1000ºC, 60s em N2 ou N2+O2 ou laser). A espessura e a rugosidade foram obtidas com a ajuda da técnica de reflectometria de raios-X (XRR). A proporção molar de háfnio adotada no processo de obtenção dos filmes foi confirmada através de análises RBS e WDS. Por XRD, foi verificado o caráter amorfo e a separação de fases nos aluminatos e, por espalhamento de raios-X em ângulo-rasante e pequena abertura (GISAXS), foram analisadas as novas fases formadas. Por fim, da análise CV, foram obtidos EOT9,54nm, resistência série (Rs68,3) e a permissividade elétrica para o aluminato de háfnio (high-k15,2). Finalmente, uma modelagem da admitância associada à corrente de fuga em função da frequência foi proposta para as estruturas MOS. / In this work, MOS capacitors were electrically characterized using alumina (Al2O3) and hafnium aluminate (AlxHf1-xOy) as gate dielectrics; also, the same dielectrics films were physically characterized. Anodic alumina was obtained from oxidation of evaporated aluminum films immersed in nitric acid for 4 or 6 min for different last step cleanings of the p-Si (100) substrates: diluted hydrofluoric acid (DHF) or sulfur peroxide mixture (SPM). Rutherford Backscattering (RBS), Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS) have shown the formation of stoichiometric alumina and the dielectric amorphous structure was revealed by X-Ray Diffraction (XRD). From Capacitance x Voltage curves (CV), it was obtained the equivalent oxide thickness (EOT2.8nm), interface trap density (Dit1.4x1011ev-1cm-2) and Al2O3 dielectric constant (high-k10.6). The admittance that represents the leakage process was modeled according to Frenkel-Poole emission, Fowler-Nordheim tunneling and/or constant leakage admittance. Hafnium aluminates (AlxHf1-xOy) were obtained on (100) silicon wafer surfaces by Atomic Layer Deposition (ALD) for different hafnium molar ratios (25, 50 or 75%) and for different treatments (1000ºC, 60s in N2 or N2+O2 or laser). Thickness and roughness were extracted from X-Ray Reflectometry (XRR) spectra. The hafnium molar ratios used in ALD process were confirmed by RBS and WDS. XRD analysis was used to establish the amorphous structure and phase separation in the aluminates after thermal treatments and Grazing-Incidence Small-Angle X-Ray Scattering (GISAXS) was used to analyze the new phases formed. From CV analysis, it was extracted EOT9.54nm, series resistance (Rs68.3) and dielectric constant from hafnium aluminate (high-k15.2). Finally, the admittance that represents the leakage was modeled in function of the frequency for the MOS structures.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-03-16T13:43:10Z No. of bitstreams: 1 Gleiton Ariel Guedes Pires_.pdf: 999723 bytes, checksum: c4e2ac031c9624b170d72249a1b0512d (MD5) / Made available in DSpace on 2017-03-16T13:43:10Z (GMT). No. of bitstreams: 1 Gleiton Ariel Guedes Pires_.pdf: 999723 bytes, checksum: c4e2ac031c9624b170d72249a1b0512d (MD5) Previous issue date: 2016-10-25 / FINEP - Financiadora de Estudos e Projetos / itt Chip - Instituto Tecnológico de Semicondutores da Unisinos / O Brasil apresenta grande potencial de geração de energia solar fotovoltaica, em um contexto de crescente demanda de energia. Em vista disso, torna-se necessária a correta e eficaz caracterização elétrica dos módulos fotovoltaicos. Esta caracterização é importante tanto na determinação da curva I-V (corrente – tensão), quanto em outros parâmetros (produtividade fotovoltaica 𝑌�������𝑓�������, perdas de captura Lc e desempenho global PR) de estimativa de produtividade energética. Este trabalho descreve a metodologia utilizada para a caracterização de quatro tecnologias de módulos fotovoltaicos (monocristalino, policristalino, CIGS e silício amorfo) e uma análise de produtividade energética para a cidade Porto Alegre – RS. Para tanto, foi estipulado um gerador fotovoltaico de 1kW pico, considerando um sistema conectado à rede com Fator de Dimensionamento (FDI) igual a 1,0. Utilizando-se o software PVsyst, foram quantificadas as produtividades energéticas devido à inclinação de instalação e à variação azimutal. A análise dos resultados levou em conta três parâmetros: a produtividade dos módulos, as perdas de captura e o desempenho global do sistema PR. Foram analisadas diversas configurações de posicionamento e de inclinação de instalação dos módulos e, posteriormente, foi realizado um comparativo entre os resultados obtidos em relação à produtividade energética na posição de referência, que consiste em instalar os módulos para o norte geográfico com inclinação próxima à latitude do local. A pesquisa indica que os módulos monocristalino e policristalino apresentam bons desempenhos orientados entre leste e oeste com ângulos de inclinação de até 40°. Os módulos CIGS e a-Si apresentam bons índices desempenho orientados a norte e oeste com ângulos de inclinação de até 30°. / The fat the Brazil presents a major photovoltaic solar energy generation, allied to the increasing energy demand, it makes necessary the correct and efficient photovoltaic modules electric characterization. This characterization is important to the determination of the I-V curve (current-tension), as well as in other parameters (Yield Factor Yf, capture losses Lc and performance ratio PR) for the estimate energy productivity. This study describes the methodology utilized for the characterization of four photovoltaic modules technologies (monocrystalline, polycrystalline, CIGS and amorphous silicon) and an energy productivity analysis for the city of Porto Alegre – RS. For that, was stipulated a 1kW peak photovoltaic generator, considering a grid-connected system with a Sizing Factor (FDI) equal to 1,0. Using the PVsyst software, Power productivity was quantified due to the installation inclination and the azimuthal variation. The results analysis took in account three parameters: module productivity, capture losses, performance ratio of the system. Several positioning configurations and modules installation inclination were analyzed. Posteriorly, a comparison was made between the results gathered according to the power productivity in the reference position, which consists in installing the modules to the geographic north with inclination close to the local latitude. The research indicates that the monocrystalline e polycrystalline modules present good performance when oriented between east and west with inclination angles up to 40º. The CIGS and a-Si modules present good ratio when oriented north and west with inclination angles up to 30º

The development of new materials with novel properties plays an important role in improving our lives and welfare. Research in Nanotechnology can provide e.g. cheaper and smarter materials in applications such as energy storage and sensors. In order for this development to proceed, we need to be able to characterize the material properties at the nano-, and even the atomic scale. The ultimate goal is to be able to tailor them according to our needs. One of the great challenges concerning the characterization of nano-sized objects is how to achieve the physical contact to them. This thesis is focused on the contacting of nanoobjects with the aim of electrically characterizing them and subsequently understanding their electrical properties. The analyzed nanoobjects are carbon nanosheets, nanotetrapods, nanoparticles and molecular systems. Two contacting strategies were employed in this thesis. The first strategy involved the development of a focused ion beam (FIB) based nanocontact platform. The platform consists of gold nanoelectrodes, having nanogaps of 10-30 nm, on top of an insulating substrate. Gold nanoparticles, double-stranded DNA and cadmium telluride nanotetrapods have been trapped in the gaps by using dielectrophoresis. In certain studies, the gold electrodes have also been coated with conducting or non-conducting molecules, prior to the trapping of gold nanoparticles, in order to form molecular junctions. These junctions were subsequently electrically characterized to evaluate the conduction properties of these molecular systems. For the purpose of better controlling the attachment of molecules to the nanoelectrodes, a novel route to synthesize alkanedithiol coated gold nanoparticles was developed. The second contacting strategy was based on the versatility of the FIB instrument as a platform for in-situ manipulation and electrical characterization of non-functionalized and functionalized carbon nanosheets, where it was found that the functionalized samples had an increased conductivity by more than one order of magnitude. Both contacting strategies proved to be valuable for building knowledge around contacting and electrical characterization of nanoobjects

Direct conversion of solar energy, which is the most powerful and unlimited one among the renewable energy sources / into the electrical energy by the photovoltaic devices, is a promising way of meeting the energy needs of future. Thin film semiconductor materials show great promise for the production of efficient, low-cost solar cell devices. Recently advanced research on thin film photovoltaics in all aspects, has attracted intense attention. Thin film semiconductors for the photovoltaic applications are deposited in large areas by different methods. In this study, deposition and characterization of CuIn1-x GaxSe2 ( CIGS ) semiconductor thin films by thermal evaporation and e-beam evaporation methods were investigated. Material properties and deposition parameters of the thin films are aimed to be optimized for solar cell applications. Structural properties of the deposited CIGS thin films were examined through X-ray diffraction and Energy Dispersive X-ray Analysis. The temperature dependent electrical conductivity, Hall effect and photoconductivity of these samples have been measured between 100 and 400 K. For the optical characterization of CIGS thin films, the transmission measurements have been carried out in the wavelength region of 325-900 nm. The changes in the structural, electrical and optical properties of samples through post-depositional annealing effect were also analyzed.

Single crystals of GaSe were grown from the melt using 3-zone vertical Bridgman-Stockbarger system. In order to determine the doping effect, nitrogen and silicon ions were implanted to the grown crystals. Surface morphology and stoichiometry were examined using scanning electron microscope equipped with EDAX and structure properties were examined by x-ray diffraction technique. It was observed that the resulting ingot was stoichiometric and the structure was hexagonal. To identify the effects of ion implantation on the physical properties of the samples depending on annealing / electrical conductivity, hall measurements, current-voltage characteristics, photoconductivity and photoluminescence measurements were carried out in the temperature range of 100-450 K. Also spectral transmission measurements were carried out for all the samples at room temperature. It was observed that both N- and Si- implantation followed by annealing process decreased the resisitivity values from 107 to 103 (&amp / #61527 / -cm). Temperature dependent conductivity measurements were analyzed to deduce the dominant transport mechanisms. The trap levels were also investigated by the space charge limited currents (SCLC) measurements. The temperature dependence of hole concentrations showed that as-grown, N- and Si-implanted samples behave as partially compensated p-type semiconductors. Using suitable statistical method, transport parameters such as acceptor level, donor and acceptor concentrations were extracted from the experimental data. Trapping centers and recombination mechanisms were determined from the temperature dependent photoconductivity measurements by investigating the relation between photocurrent and illumination intensity. N- and Si- implantation effects on GaSe were also examined by spectral photoconductivity and transmission measurements. And lastly, radiative recombination mechanisms in as-grown GaSe were investigated through photoluminescence (PL) measurements and the information related to the structural defects, the exciton levels and the structure of the forbidden gap were investigated.

In this work, structural, electrical and optical characterization of as-grown, Ge-implanted, and annealed GaSe single crystals grown by using 3-zone vertical Bridgman-Stockbarger system, have been studied by carrying out X-ray Diffraction (XRD), electrical conductivity, Hall effect, photoconductivity, and spectral transmission measurements. The temperature dependent electrical conductivity of these samples have been measured between 100 and 400 K. As a result, it was observed that upon implanting GaSe with germanium following annealing process, the resistivity is reduced from 2.1x109 to 6.5x105 &amp / #937 / -cm. Also it was found that Ge-implantation followed by annealing at 500 oC increases the conductivity in exponential fashion. From the temperature dependent conductivities, the activation energies have been found to be 4, 34 and 314 meV for as-grown, 36 and 472 meV for as-implanted, and 39 and 647 meV for implanted and annealed at 500 oC GaSe single crystals. Using XRD measurements it was observed that there is an increase in peak intensities at specific annealing temperatures (300 and 500 C) and a decrease in higher annealing temperatures (700 C). Temperature dependent carrier concentration and Hall mobility measurement were performed in the temperature range of 230 - 410 and 100 - 400 K for as-grown and Ge-implanted and annealed GaSe samples, respectively. All of the samples in this study were found to be p-type with the help Hall measurements. In addition, the density of donor and acceptor atoms are found for each sample and results are compared with each other. In addition, using photoconductivity measurement the relation between photocurrent and illumination intensity and the character of photoconduction were determined. As a result it was found that while at specific temperature intervals impurity scatterings are dominant, in other intervals phonon scatterings start to dominate. Finally, in order to determine annealing dependent change of band gap of unimplanted and Ge-implanted GaSe samples at room temperature, the transmission measurement have been carried out as a optical characterization part of our study. As a consequence of this measurement it was observed that there is almost no considerable change in optical band gap of samples with increasing annealing temperatures for as-grown GaSe samples and a slight shift of optical band gap toward to high energy for Ge-implanted samples with annealing process.

In the present study, the effect of S and Se substitution on structural, electrical and optical properties of AgGa(Se2-xSx) thin films has been investigated. AgGa(Se0.5S0.5 )2 thin films were prepared by using the thermal evaporation method. X-ray diffraction (XRD) analysis has revealed that the transformation from amorphous to polycrystalline structure took place at about 450 oC. The detailed information about the stoichometry and the segregation mechanisms of the constituent elements in the structure has been obtained by performing both energy dispersive X-ray analysis (EDXA) and X-ray photoelectron spectroscopy (XPS) measurements. AgGaSe2 thin films were deposited by using both electron-beam (e-beam) and sputtering techniques. In e-beam evaporated thin films, the effect of annealing on the structural and morphological properties of the deposited films has been studied by means of XRD, XPS, scanning electron microscopy (SEM) and EDXA measurements. Structural analysis has shown that samples annealed between 300 and 600 oC were in polycrystalline structure with co-existance of Ag, Ga2Se3, GaSe, and AgGaSe2. The variation of surface morphology, chemical composition and bonding nature of constituent elements on post-annealing has been determined by EDXA and XPS analyses. AgGaSe2 thin films were also prepared by using sputtering technique. XRD measurements have shown that the mono-phase AgGaSe2 structure is formed at annealing temperature of 600 oC. The crystal-field and spin-orbit splitting levels were resolved. These levels around 2.03 and 2.30 eV were also detected from the photospectral response measurements. Thin films of Ag-Ga-S (AGS) compound were prepared by using AgGaS2 single crystalline powder and deposition of the excess silver (Ag) intralayer with double source thermal evaporation method. As a consequence of systematic optimization of thickness of Ag layer, Ag(Ga,S) with the stoichiometry of AgGa5S8 and AgGaS2 were obtained and systematic study to obtain structural, electrical and optical properties was carried out.

Nano-objects have unique properties due to their sizes, shapes and structure. When electronic properties of such nano-objects are used to build devices, the control of interfaces at atomic level is required. In this thesis, systems were built that can not only electrically characterize nano-objects, but also allow to analyze a large number of individual nano-objects statistically at the example of graphene and nanoparticle-molecule-nanoelectrode junctions. An in-situ electrical characterization system was developed for the analysis of free standing graphene sheets containing defects created by an acid treatment. The electrical characterization of several hundred sheets revealed that the resistance in acid treated graphene sheets decreased by 50 times as compared to pristine graphene and is explained by the presence of di-vacancy defects. However, the mechanism of defect insertion into graphene is different when graphene is bombarded with a focused ion beam and in this case, the resistance of graphene increases upon defect insertion. The defect insertion becomes even stronger at liquid N2 temperature. A molecular electronics platform with excellent junction properties was fabricated where nanoparticle-molecule chains bridge 15-30nm nanoelectrodes. This approach enabled a systematic evaluation of junctions that were assembled by functionalizing electrode surfaces with alkanethiols and biphenyldithiol. The variations in the molecular device resistance were several orders of magnitude and explained by variations in attachment geometries of molecules.  The spread of resistance values of different devices was drastically reduced by using a new functionalization technique that relies on coating of gold nanoparticles with trityl protected alkanedithiols, where the trityl group was removed after trapping of nanoparticles in the electrode gap. This establishment of a reproducible molecular electronics platform enabled the observation of vibrations of a few molecules by inelastic tunneling spectroscopy. Thus this system can be used extensively to characterize molecules as well as build devices based on molecules and nanoparticles.

Ce sujet de thèse a pour objectif principal la conception de protection contre les décharges électrostatiques (ESD) en technologie silicium avancée sur isolant film mince (FDSOI) avec la compatibilité substrat massif. Ceci suppose une caractérisation ESD des dispositifs élémentaires déjà existants et une conception complète de nouveaux dispositifs sur technologie FDSOI. Ces caractérisations se feront, soit en collaboration avec les équipes de caractérisation ESD présents à STMicroelectronics-Crolles, soit directement par le doctorant grâce au banc de test ESD présent dans le laboratoire pour les développements plus en amont si besoin. La caractérisation fine des mécanismes physiques et des performances des composants sera menée à IMEP qui dispose des équipements adéquats (bancs de mesures en basse et haute température, bruit, pompage de charge, etc) et d’une compétence scientifique incontournable. Il sera ensuite nécessaire d’effectuer des choix de stratégies de protection ESD en fonction des applications et des circuits visés par les équipes de STMicroelectronics. On gardera à l’esprit la notion de fiabilité dès la conception de la protection. Une des stratégies envisagée pour la réalisation de protections ESD compatibles avec des films ultra-minces est l’intégration de ces dispositifs sur substrats hybrides. En effet, il a été démontré chez STMicroelectronics en partenariat avec le LETI qu’il était possible de co-intégrer à partir d’un substrat SOI des dispositifs FDSOI ainsi que des dispositifs bulk. Ceci est rendu possible au moyen d’un réticule supplémentaire qui permet de venir retirer le film de silicium et l’oxyde enterré aux endroits voulus. Ainsi la protection ESD est similaire à celle réalisée sur silicium massif mais avec des implantations compatibles avec des dispositifs à film mince. Les dispositifs sont donc sensiblement différents de ceux réalisés sur bulk et nécessitent une caractérisation approfondie afin de les optimiser au mieux. Une approche ambitieuse vise à concevoir des composants SOI inédits, utilisables pour la protection ESD. Ce volet du travail sera en autre effectué sous la responsabilité de l’IMEP qui a récemment inventé et publié plusieurs types de transistors révolutionnaires : Z2-FET, TFET et BET-FET [12-14].Les études se feront sur des dispositifs silicium sur isolant issus des technologies de fabrication STMicroelectronics. Pour ce faire, il sera nécessaire d’appréhender les techniques de fabrication. Dans ce cadre, une simulation des processus de fabrication est envisagée sous la chaîne d’outil ISE-TCAD en C20nm et technologies futures. Tout d’abord ceci permettra d’embrasser l’ensemble des possibilités inhérentes à la création de nouveaux composants dans la technologie considérée et ensuite cette étude préliminaire fournira des structures de simulation pour les configurations ESD. Parallèlement, les outils TCAD de simulation physique du semi-conducteur à gap indirect type silicium seront mis à profit pour étudier plus précisément le comportement du composant élémentaire de protection ESD. Ces éléments peuvent être par exemple de type : diode, ggNMOS, Tr BIMOS, SCR ou SCR, T2, Beta-matrice, PPP… La synergie avec l’IMEP est essentielle pour l’identification et l’analyse des mécanismes physiques gouvernant le fonctionnement des dispositifs. Notamment, l’objectif principal est d’intégrer la protection ESD dans son application finale et d’évaluer son efficacité et son dimensionnement par l’intermédiaire de paramètres géométriques par exemple. Il sera également possible de réaliser des simulations mixtes afin de mieux tenir compte des effets 3D de la structure (effet de coins, dépolarisation de substrat) et de connaître l’influence des circuits de déclenchement associés à cette protection. L’optimisation de l’implantation de la protection ESD sera alors envisageable au regard des résultats de simulation. On se place ici dans le cadre d’une démarche de Co-Design de protection ESD. / "The thesis main objective is the design of protection againstelectrostatic discharge (ESD), for deep submicron (DSM)state-of-the-art fully depleted silicon-on-insulator technology (FDSOI).This requires the ESD characterization of existing elementary devicesand design of new FDSOI devices. The detailed characterization of thephysical mechanisms and device performance will be conducted at IMEPwhich has adequate facilities and scientific competence in this field.It will then be necessary to make choices for ESD protectionstrategies based on circuit applications by STMicroelectronics. Anambitious approach aims to develop novel SOI components used for ESDprotection. This part of the work will be performed under theresponsibility of IMEP as it has has recently invented and publishedseveral types of revolutionary transistors Z 2-FET, TFET andBET-FET. It will be necessary to understand the fabrication processtechnology of STMicroelectronics. In this framework, 3D simulation ofthe technology will be performed on TCAD software for 28nm FDSOI andfuture technologies. Physical simulation, with TCAD tools of thesemiconductor will be used to study more precisely the behavior of theelementary devices of ESD protection. Collaboration with the IMEP isessential for the identification and analysis of the physicalmechanisms governing device operation.In particular, the main objective is to integrate ESD protection andevaluate its effectiveness and design. It will also be possible toperform mixed-mode simulation to better analyse the effects of the 3Dstructure (corner effects, depolarization of substrate) and evaluatethe influence of trigger circuits associated with this protection.Optimizing the implementation of ESD protection will then be possible.Having studied from a theoretical point of view and numericalsimulation, ESD protection cells and trigger circuits associated withthe ESD protection strategy, qualification on silicon will be applied.This will be done by a test vehicle in the chosen SOI technology, andelectrical characterization of the structures and protection networkswill follow. Finally, the ESD performance will be analyzed to provideoptimization of the design and the choice of ESD protection strategybased on targeted applications."

abstract: Amorphous oxide semiconductors are promising new materials for various optoelectronic applications. In this study, improved electrical and optical properties upon thermal and microwave processing of mixed-oxide semiconductors are reported. First, arsenic-doped silicon was used as a model system to understand susceptor-assisted microwave annealing. Mixed oxide semiconductor films of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) were deposited by room-temperature RF sputtering on flexible polymer substrates. Thermal annealing in different environments - air, vacuum and oxygen was done. Electrical and optical characterization was carried out before and after annealing. The degree of reversal in the degradation in electrical properties of the thin films upon annealing in oxygen was assessed by subjecting samples to subsequent vacuum anneals. To further increase the conductivity of the IGZO films, Ag layers of various thicknesses were embedded between two IGZO layers. Optical performance of the multilayer structures was improved by susceptor-assisted microwave annealing and furnace-annealing in oxygen environment without compromising on their electrical conductivity. The post-processing of the films in different environments was used to develop an understanding of mechanisms of carrier generation, transport and optical absorption. This study establishes IGZO as a viable transparent conductor, which can be deposited at room-temperature and processed by thermal and microwave annealing to improve electrical and optical performance for applications in flexible electronics and optoelectronics. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2011