Tesis sobre el tema "Contact resistance"
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Jovell, Megias Ferran. "Contact resistance and electrostatics of 2DFETs". Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/664041.
Texto completoIn the last decade, the rise of graphene and other 2-dimensional materials revolutionized materials science. The new physics brought by these new materials opened up the possibilities of new devices with outstanding characteristics. In the field of radiofrequency electronics, some of these devices are predicted to bridge the terahertz gap in the frequency spectrum. In this thesis, several simulation techniques have been employed to study different devices with this long term goal in mind. In first place, a single-layer molybdenum disulfide (MoS$_2$) field effect transistor (FET) has been studied using the drift-diffusion model. To delve deeper into this, a MoS$_2$ $p-n$ junction has also been studied in this framework. Even though the drift-diffusion model is suited for bulk materials, a set of effective parameters was found. With it, it has been possible to reproduce the on-current of experimental data of the single-layer MoS$_2$ FET, but not the subthreshold swing. On the other hand, the MoS$_2$ $p-n$ junction yielded valuable results for the study of the depletion region. One of the hurdles that must be overcome in order to harness the possibilities of graphene and other 2D materials so that the performance of high frequency devices is not compromised is to achieve a low enough contact resistance (R$_c$) between the metal contact and the channel. In this thesis, an intermediate graphite layer between the metal contact and the graphene layer is proposed in order to achieve the 100 $\Omega\cdot\mu$m mark that is often quoted to be the upper limit for $R_c$ not to be the limiting factor. A graphite-graphene top contact structure is proposed and studied under ballistic transport by density functional theory (DFT) and Non-Equilibrium Green's Function Theory (NEGF) to calculate the contact resistance. In particular, several overlap amounts between graphene over the graphite bulk were studied. The results obtained are very promising for doped samples of graphene. To assess these results, a current path analysis was conducted using the eigenchannel formalism. This analysis showed that the transfer of electrons was done through the area of contact instead of an edge. It was concluded that graphite was a suitable buffer to reduce R$_c$ for metal-graphene contacts. Finally, in order to understand better some of the experimental results in the contact resistance of metal-graphene contacts, the objective was to generate realistic atomic configurations using Molecular Dynamics. For that, a first step is to parametrize the metal-carbon interactions. The bond order potential (BOP) force field was chosen for this as it is a force field that can accurately describe the metal-carbon covalent bond. The metal-metal bond is described using the embeded atom potential (EAM) and the carbon-carbon interaction, by the Tersoff force field. The BOP force field has a ten parameter set that describe the characteristics of the bond: equilibirum distance, bond energy, etc. Using Parallel Tempering Monte Carlo (PTMC) optimisation algorithm trained from first principles calculations of small metal particles on top of a graphene sheet, a set of parameters for the BOP force field was obtained for the Pd-C and Ni-C pairs.
Gibbins, Josh. "Thermal Contact Resistance of Polymer Interfaces". Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2856.
Texto completoThe experimental data was compared to the CMY plastic contact model, the Mikic elastic contact model and the SY elasto-plastic contact model to investigate the ability of such established thermal contact models to predict the thermal contact resistance at polymer interfaces. Based upon predictions made in regards to the mode of deformation of the asperities on the contacting surfaces the appropriate contact model showed good agreement with the experimental data for the stainless steel-stainless steel data set and the polycarbonate-stainless steel data sets. There was poor agreement between the all three contact models and the experimental data for the polycarbonate-polycarbonate data sets. It was determined that uncertainties in the proposed experimental method prevented an accurate measurement of the thermal contact resistance values for the polycarbonate-polycarbonate data sets.
The purpose of this investigation was to extend the use of established thermal contact models to polymer interfaces and to provide a comparison between the thermal contact resistance values of metal and polymer interfaces.
Thermal contact resistance for the polymer to metal interface was shown to be predicted by the Mikic elastic contact model in comparison to the metal to metal interface which was shown to be predicted by the CMY plastic contact model. The thermal contact resistance for a polymer interface was found to be on the same order as a metal interface.
Almeida, Lia Ramadoss Ramesh. "Experimental and theoretical investigation of contact resistance and reliability of lateral contact type ohmic MEMS relays". Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Theses/ALMEIDA_LIA_13.pdf.
Texto completoReshamwala, Chetak M. (Chetak Mahesh) 1979. "Contact resistance in RFID chip-antenna interfaces". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8193.
Texto completoIncludes bibliographical references (p. 21).
The purpose of this study was to determine a force-deflection relationship and a force-contact area relationship between a flat planar solid and a spherical solid in terms of material and surface properties of the two bodies. This relationship was determined and it was discovered that the force was directly proportional to both the deflection and contact area. This information is useful in the design and performance of RFID chips. The RFID chip-antenna interface is the area of greatest power loss in the system, and by determining a relationship to increase the contact area in that region, the power loss to the antenna can be reduced. Moreover, an analysis including asperities on the micro scale geometry of the solids was conducted. In the final approach to the problem, a random distribution of asperity types was analyzed. An expression was derived for the total force applied in terms of a given deflection and a range of asperity radii of curvature. A three-dimensional graph was created to show how each of these variables depends on the each other when asperities exist. This relationship is very significant, because it can be used to improve current RFID chip technology to achieve better performance. This expression can also be used to determine specifications in the manufacturing process to achieve a certain deflection or area of contact between the contacting bodies, thereby improving the current manufacturing process.
by Chetak M. Reshamwala.
S.B.
Wilson, W. Everett Jackson Robert L. "Surface separation and contact resistance considering sinusoidal elastic-plastic multiscale rough surface contact". Auburn, Ala, 2008. http://hdl.handle.net/10415/1490.
Texto completoGill, Jennifer. "AN INVERSE ALGORITHM TO ESTIMATE THERMAL CONTACT RESISTANCE". Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2546.
Texto completoM.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
Taphouse, John Harold. "Thermal contact resistance in carbon nanotube forest interfaces". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54853.
Texto completoYang, Yulin. "Evaluation of rolling contact fatigue resistance for coated components". Thesis, University of Hull, 2003. http://hydra.hull.ac.uk/resources/hull:8534.
Texto completoSun, Ta-chien. "Fundamental study of contact resistance behavior in RSW aluminum". Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1069807481.
Texto completoTitle from first page of PDF file. Document formatted into pages; contains xxviii, 314 p.; also includes graphics (some col.) Includes bibliographical references (p. 303-314). Available online via OhioLINK's ETD Center
Li, Wei 1967. "Determination of the relationship between thermal contact resistance and contact pressure based on their distributions". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26402.
Texto completoIn the experiments described in this thesis, two thin-plate specimens of steel under plane-stress loading conditions generating contact pressure distributions of various profiles at the interface, were subjected to a thermal field. Temperature measurements served as reference for the finite element modelling which, through consecutive iterations, provided the values for the thermal contact resistance distributions. Combined mechanical contact pressure and thermal contact stress distributions were considered at the interface.
The function representing the relationship between thermal contact resistance and contact pressure for various distributions was defined using the least squares method. It was revealed that although this relationship can be expressed by the single function for the whole experimental range, the deviations experienced for different slopes and forms of distributions (convex and concave), particularly noticeable for steep slopes at high contact pressure levels, could indicate the effect of macro-constriction resistance, however small its values according to the theoretical calculations might be.
Hong, Fangjun. "Droplet spreading, substrate remelting and variable thermal contact resistance in microcasting /". View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20HONG.
Texto completoFrolish, Michael Fraser. "Design criteria for rolling contact fatigue resistance in back-up rolls". Thesis, University of Sheffield, 2002. http://etheses.whiterose.ac.uk/15083/.
Texto completoTanguturi, Sai Kishan. "Effect on Contact Resistance dueto Cross Connection of MC4 Compatible Connector". Thesis, Högskolan Dalarna, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-28838.
Texto completoEby, Anne Kathryn. "Factors affecting medical-surgical area nurses' compliance with contact precautions". Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/eby/EbyA1209.pdf.
Texto completoShi, Lei Photovoltaics & Renewable Energy Engineering Faculty of Engineering UNSW. "Contact resistance study on polycrystalline silicon thin-film solar cells on glass". Publisher:University of New South Wales. Photovoltaics & Renewable Energy Engineering, 2008. http://handle.unsw.edu.au/1959.4/41425.
Texto completoBahrami, Majid. "Modeling of Thermal Joint Resistance for Sphere-Flat Contacts in a Vacuum". Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/876.
Texto completoThompson, Mary Kathryn 1980. "A multi-scale iterative approach for finite element modeling of thermal contact resistance". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42069.
Texto completoThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
Surface topography has long been considered a key factor in the performance of many contact applications including thermal contact resistance. However, essentially all analytical and numerical models of thermal contact resistance and thermal contact conductance either neglect surface topography or make simplifications and assumptions about the nature of the surface. This work combines measured surface geometry with an iterative thermal/structural finite element model to more accurately predict microscopic and macroscopic thermal contact resistance. A commercial power electronics module which exhibits both macroscopic surface form and micro scale surface roughness is analyzed using three different macro scale surface models to verify the accuracy of the model and to demonstrate the impact of geometric surface assumptions. Finally, the factors influencing the thermal/structural behavior of bolted plates are examined and recommendations for reducing both contact resistance and the overall thermal resistance of bolted plate systems are presented.
by Mary Kathryn Thompson.
Ph.D.
Locker, Graham J. "Fretting corrosion of tin-plated separable connectors used in automotive applications". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/32165.
Texto completoYang, Jing 1988. "Grinding effects on surface integrity, flexural strength and contact damage resistance of coated hardmetals". Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/396135.
Texto completoEn este trabajo se estudia la influencia de la integridad superficial del sustrato sobre diferentes propiedades mecánicas (resistencia tanto a la rotura en flexión como al daño inducido por contacto) y tribológicas (resistencia al rayado así como el comportamiento bajo solicitaciones de indentación Brale) de una calidad fina de metal duro (WC-13% peso Co) recubierta con una capa de TiN. La investigación incluye la consideración de cuatro acabados superficiales: en condiciones de sinterizado (AS), rectificado (G), pulido (P), y rectificado más un tratamiento térmico de recocido (GTT). Los resultados indican que el rectificado induce alteraciones importantes en la integridad superficial: se incrementa la rugosidad y emerge una textura superficial; se evidencia la existencia de microfisuras, anisotrópicamente distribuidas a nivel subsuperficial; se introduce una deformación muy severa, lo cual da lugar a un refinamiento de la microestructura y transformación de fase en el ligante metálico; y finalmente, se inducen tensiones residuales compresivas elevadas. Estas tensiones se ven reducidas durante las etapas subsecuentes de pulverización por bombardeo iónico y deposición de la capa cerámica. Por su parte, las tensiones residuales referidas si son completamente eliminadas en las muestras GTT, aunque sin que el tratamiento posterior al rectificado induzca cambio alguno respecto al daño existente. Éste no es el caso para la fase metálica, donde el tratamiento de recocido conlleva la aparición de una inesperada microporosidad, recristalización microestructural a nivel subsuperficial y la reversión de la transformación de fase inducida durante el rectificado. La operación de rectificado resultó en un incremento significativo de la resistencia a flexión del metal duro. Este efecto positivo se perdió parcialmente al recubrir el material. Por el contrario, la deposición de la capa de TiN promovió un aumento de la resistencia mecánica para la condición GTT. Las variaciones en resistencia a rotura determinadas se explican considerando las tensiones residuales efectivas existentes en cada caso y la ubicación, en la superficie o por debajo de ella, de los defectos críticos responsables de la rotura del material. La carga crítica para la exposición del sustrato en el ensayo de rayado resultó ser Independiente del acabado superficial, para las muestras AS, G y P. Sn embargo, el daño irreversible inducido por el indentador bajo condiciones de contacto y deslizamiento simultáneo fue discreto y localizado para las muestras G, a diferencia de la exposición continua y más pronunciada del sustrato que se evidenció en las condiciones AS y P. Por su parte, las muestras GTT mostraron una carga crítica inferior y cambios relevantes en el mecanismo de fallo correspondiente. El ensayo de indentación Brale de metales duros recubiertos indicó una mayor fragilidad y una menor resistencia a la adhesión para la calidad con menor contenido de ligante metálico. En este marco experimental, y en comparación con el acabado de pulido, se evidenció que el rectificado del sustrato favorece la delaminación, pero también inhibe la aparición de fisuras radiales en metales duros recubiertos. La respuesta observada se analiza y explica sobre las bases de la interacción entre la deformación elasto-plástica impuesta durante la indentación y las alteraciones en integridad superficial resultantes del rectificado. El rectificado del sustrato, previo a la deposición de una capa cerámica, incrementa la resistencia al daño inducido bajo solicitaciones de contacto esférico. Esta influencia positiva se evidencia en términos no solo de la nucleación de fisuras sino también de la subsecuente propagación de ellas dentro del sustrato de metal duro. La principal razón de ello son las elevadas tensiones residuales de compresión introducidas en el proceso de rectificado. Esta afirmación se sustenta por la menor resistencia al daño por contacto que se determinó en las muestras GTT recubierta
Marinkovic, Marko [Verfasser]. "Contact resistance effects in thin film solar cells and thin film transistors / Marko Marinkovic". Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1037014243/34.
Texto completoYang, Jing. "Grinding effects on surface integrity, flexural strength and contact damage resistance of coated hardmetals". Doctoral thesis, Linköpings universitet, Nanostrukturerade material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-127341.
Texto completoLiang, Te-Hui. "A numerical study of the contact behaviors in resistance spot welding steel-based sheets /". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488195633520408.
Texto completoBeyer, Robert [Verfasser]. "A constitutive contact model for homogenized tread-road interaction in rolling resistance computations / Robert Beyer". Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1128663767/34.
Texto completoJedrzejczyk, Pawel. "Analyse et quantification de l'endurance de contact électrique sous sollicitations de fretting". Thesis, Ecully, Ecole centrale de Lyon, 2010. http://www.theses.fr/2010ECDL0016/document.
Texto completoThe degradation by fretting appears as a very troublesome process in many industrial systems (spatial, automotive, nuclear industry, railway systems etc. …). This wear process makes it necessary to repair or to replace the destroyed component. The process of degradation by fretting is associated with the micro-displacement between two surfaces in contact. This type of degradation is observed in all types of contacts subjected to the vibrations or thermal variations. The degradation by fretting in electrical contact is particularly dangerous. The wear of the contacting surfaces causes a significant increase of the electrical resistance of the contact and the decay of the functional properties of the connector. This situation concerns especially the low tension connectors very sensible to the fluctuations of the electrical resistance. In order to avoid this situation the automotive industry and its suppliers, the manufacturers of the electrical connectors, are looking for new materials and coatings.The objective of this thesis consists to develop the methodology of choice of the coating materials in order to optimise the lifetime of the electrical contact. The study focuses mainly on the influence of the mechanical conditions, the displacement amplitude in particular, on the performance of the electrical connector
Narayanaswamy, Anand Subramanian. "A Non-Contact Sensor Interface for High-Temperature, MEMS Capacitive Sensors". Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1275675071.
Texto completoBarreto, Eduardo Xavier. "Design construtal de caminhos condutivos com geometrias em forma de "i" e "t" para resfriamento de corpos geradores de calor considerando a resistência térmica de contato". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/133124.
Texto completoThis work applies Constructal Design to investigate the heat transfer through high conductive pathways with defined geometries. The objective is to find the configuration which reduces the maximal excess of temperature considering the areas with high and low thermal conductivity are constants. Thus, the object studied here is a volume with a finite area and heat generation. The outside heat flux is conducted through a high thermal conductive pathway. Here, special attention is given to the thermal contact resistance between the high conductive pathway and the solid body, where a third material with a thermal resistance equivalent to the thermal contact resistance is inserted between them. A numerical treatment was given in order to solve the heat diffusive equation. It was used a numerical code based on finite elements and the toolbox – PDETool, Partial Differential Equations Tool, which is part of the MatLab® applicative. The numerical treatment was achieved considering "I" and "T" geometries for the high conductive pathways keeping the areas fraction constants and varying the lengths of both high conductive and the equivalent thermal contact layer materials. The optimization was performed considering the degrees of freedom of each geometry, where the optimized values for the ideal situation, i.e., perfect thermal contact were compared with the results considering the thermal contact resistance. The results indicate that the thermal contact resistance can increase the excess of temperature, as well as it has a significant effect on the optimal configurations when using perfect thermal contact or taking into account the thermal contact resistance for "I" and "T" shaped geometries.
Luo, Xinhang. "Few-Layer MoS2 Thin Films Grown by Chemical Vapor Deposition". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417656899.
Texto completoBourouga, Brahim. "Etude d'une methode de mesure instationnaire de resistance thermique de contact entre parois cylindriques concentriques minces". Nantes, 1986. http://www.theses.fr/1986NANT2063.
Texto completoWang, Feng. "Controlling the Hydrophilicity and Contact Resistance of Fuel Cell Bipolar Plate Surfaces Using Layered Nanoparticle Assembly". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1268081049.
Texto completoMisra, Prashant. "Simultaneous Studies Of Electrical Contact Resistance And Thermal Contact Conductance Across Metallic Contacts". Thesis, 2009. http://hdl.handle.net/2005/953.
Texto completoGonzalez, Castro Gabriela, Maksims Babenko, S. Bigot, John Sweeney, Hassan Ugail y Benjamin R. Whiteside. "Thermal contact resistance in micromoulding". 2011. http://hdl.handle.net/10454/5425.
Texto completoThis work outlines a novel approach for determining thermal contact resistance (TCR) in micromoulding. The proposed technique aims to produce TCR predictions with known confidence values and combines experimental evidence (temperature fields and contact angle measurements) with various mathematical modelling procedures (parametric representation of surfaces, finite element analysis and stochastic processes). Here, emphasis is made on the mathematical aspects of the project. In particular, we focus on the description of the parametric surface representation technique based on the use of partial differential equations, known as the PDE method, which will be responsible for characterizing and compressing micro features in either moulds or surface tools.
EPSRC
Oloumi, Arusha. "Cell-cell contact induced resistance to etoposide". Thesis, 2002. http://hdl.handle.net/2429/13531.
Texto completoLin, Ching-Ting y 林敬庭. "Improving Contact Resistance of Molybdenum Disulfide Transistor". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/58554630904620697412.
Texto completo國立交通大學
電子研究所
105
The atomic thickness of 2D materials effectively mitigates the short channel effect, and opens up new possibilities to scale device and extend the Moore’s law. Among 2D materials, transition metal dichalcogenides-MoS2 has attracted many attentions as the channel material of the transistor and prompted new developments of numerous electric and optical devices. However, large contact resistance limited the MoS2 transistor performance. We synthesize monolayer MoS2 on sapphire substrate by chemical vapor deposition method, and then transfer MoS2 film to HfO2 dielectric substrate. We carefully engineer the interface between source/drain (S/D) metal and MoS2 to find stable methods for reducing contact resistance. In this thesis, sulfur vacancies generated by H2 plasma treatment was found to result in band gap narrowing from optical analysis and VASP simulation. If only S/D region received the H2 plasma treatment, the band gap narrowing reduced the Schottky barrier between S/D metal and MoS2 and therefore reduced contact resistance. F- and Cl-based plasma treatment induced p-type doping in MoS2 transistors, and improved the p-type conduction of WSe2 transistors after the Cl2 plasma treatment. A SiO2 capping layer was utilized to suppress the potential damage of the device fabrication process on monolayer MoS2. Furthermore, the SiO2 capping layer influences the contact between S/D metal and MoS2 due to charge transfer. Replacing S/D metal from Mo to Pd, which has a higher work function and less interaction with MoS2, shows reduced contact resistance. Although the Schottky barrier is higher, a large band bending can be achieved by applying gate voltage. We attributed this to the less interaction between Pd and MoS2.
Chen, Ming-Lei y 陳明磊. "The research of ohmic contact and specific contact resistance on p-GaN". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/05653274888356430456.
Texto completoChia-Chin, Chuang y 莊家慶. "Contact Temperature and Thermal Contact Resistance Based on a Fractal Surface Model". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/76841294677409212277.
Texto completo國立臺灣大學
機械工程學研究所
89
On the interface between two apparently conforming solids, only some asperities are really in contact. The real contact area is much less than the apparent contact area. Most of the heat or energy can only pass through these small contact areas. This distortion of the heat flow causes an increase in thermal resistance that is known as the thermal contact resistance. To date, the influence of surface roughness on the contact resistance and temperature has not been clearly identified. Existing theories on contact temperature and resistance have two major shortcomings: the first one is that they employed non-fractal surface models; the other one is that they neglected the effects of thermal deformation. Use of non-fractal models makes it difficult to unambiguously identify the parameters of surface models. Because of the neglect of thermal deformation, existing models can not simulate the directional effect of contact resistance. In this thesis, we study the thermal contact resistance by employing a fractal surface model and considering the effects of thermal deformation. First, we determine the relationship between the contact temperature, deformation and contact pressure of a single asperity. Then the force equilibrium and compatibility conditions are employed to find the contact force, the total heat passing through the interface, and the associated contact resistance. At last, we study quantitatively the effects of material properties, fractal dimensions, contact pressure, temperature and the direction of heat flow on the contact temperature and resistance.
Prasad, V. Siddeswara. "Studies On Electrical Contact Resistance And Coefficient Of Friction Across Sliding Electrical Contacts". Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1534.
Texto completoKao, Ming-Hong y 高銘鴻. "A Study on the Contact Resistance Reduction in Metal/n-type Germanium Contacts". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/58001522062615986997.
Texto completo國立交通大學
電子研究所
101
With the rapid progress of nano-fabrication technology, Si based MOSFETs have been successfully scaled down to 20 nm regime. However, the continued scaling will be a problem due to several physical and technical limitations, and the device performance may not be improved by further scaling down. Many methods have been purposed to solve this problem, because of the higher carrier mobilities and better process compatibility, Ge is considered a potential candidate to replace silicon as the next generation channel material. However, the contact resistance between metal and n-type Ge is very high due to the high Schottky barrier height. To implement high performance Ge NMOSFETs, reducing the contact resistance of metal/n-type Ge is critical. In this thesis, two different methods to reduce the contact resistance of metal/n-type Ge are investigated. One is inserted dielectric-inserted junction and the other is modified Schottky barrier junction. The former is to modulate the Schottky barrier height and the latter is to enhance the doping concentration at the metal/Ge interface. The dielectric insertion method has been reported in literature. Both Al2O3 and TiO2 have been used as the inserted dielectric layer. Because of the lower conduction band offset of TiO2 to Ge, it can not only reduce the Schottky barrier height but also achieve low tunneling resistance and high conduction current. However, the mechanism has not been well understood. In this thesis, we first observed that the Fermi level pinning effect is a very weak function of the TiO2 thickness so we infer that the Schottky barrier height reduction by the dielectric insertion is due to the change of the pinning position. The amount of fixed charges in the thin dielectric layer is extracted from a MIS structure and it is found that the small amount of fixed charges is not sufficient to produce such a pronounced voltage drop to modulate the Schottky barrier height. It is thus recommended that the mechanism of the dielectric insertion method mainly comes from interface dipoles. Besides, it is observed that after annealing at 300 °C for 30 minutes, the Schottky barrier height will increase. The increase of the Schottky barrier height increase with the increasing of the annealing temperature. According to the microstructural analysis, it is postulated that the crystallization of the dielectric layer after annealing is the main reason for the increase of Schottky barrier height. Due to the dielectric constant increase after crystallization, the capacitance of the dielectric capacitor increases and causes smaller voltage drop so that the Schottky barrier height increases. The thicker TiO2 dielectric layer has smaller capacitance, which might be the reason for the lower Schottky barrier height. In the modified Schottky barrier method, dopants are implanted into metal-germanide instead of Ge so that the number of defects formed in substrate could be negligible, which would mitigate the dopants diffusion caused by the interaction between defects and dopants. A thin and high doping concentration layer can be formed at the metal/semiconductor interface. Increasing the activation temperature will achieve higher doping concentration. But the allowed annealing temperature is limited by the poor thermal stability of NiGe films. To improve the thermal stability of NiGe films, a Si layer is inserted between Ni and Ge before annealing. The result shows that the thermal stability of NiGe film is improved by this Si-insertion layer from 500 °C to 550 °C. Using the Si-insertion technique, the activation temperature of MSB junctions can be raised to 550 °C so that the doping concentration is enhanced. Compared to the conventional junction with direct implantation into Ge, the junction depth is much shallower and the carrier concentration is much higher for the MSB junction which suggests that the MSB process is attractive for the short channel Ge MOSFETs. In summary, this thesis proposed the mechanism of the Schottky barrier height modulation by dielectric insertion. The thickness effect and annealing effect are also explained. A new method, modified Schottky barrier method, is propsed to reduce the contact resistance between metal and n-type Ge by forming a thin and high concentration layer at the metal/Ge interface. This method is very promising for short channel Ge NMOSFET.
Jain, Rajiv. "ECR Studies Across Bare And Gold Coated Metal Contacts At Low Temperatures". Thesis, 2009. http://hdl.handle.net/2005/1036.
Texto completoLin, Chung-pao y 林忠寶. "Low specific contact resistance and high reflectivity of Pt/Ag contacts on p-GaN". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/73365001469281437989.
Texto completo國立中央大學
化學工程與材料工程研究所
96
The electrical and optical properties of metal scheme contacts on p-GaN were investigated widely. In this paper, firstly, we studied the transmittance of Pt ohmic layer on p-GaN. Then, the contact resistance and reflectivity of Pt / Ag was evaluated. Pt p-contact with two different thickness 5 and 10 nm were studied on p-GaN. Pt / p-GaN samples were annealed at N2 ambient for 5 minutes and annealing temperatures were 500℃~800℃. We find the specific contact resistance and transmittance of Pt raise with increasing annealing temperatures. After specific contact resistance and transmittance measurement, 150 nm Ag layer was deposited on the annealed Pt contact pads. Finally, the metal scheme of Pt/Ag/p-GaN was investigated by annealing together at at N2 ambient for 5 minutes and annealing temperature was 500℃. The lowest specific contact resistance of Pt / Ag we can get is about 4.5x10-3 Ω-cm2。 At 470 nm, the highest reflectivity of Pt / Ag is about 83%.
Jia-BinChen y 陳加彬. "A study of graphene to graphene contact resistance". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/n8kgrk.
Texto completoYa-PeiTseng y 曾雅珮. "Analysis of IC Socket Spring Pin Contact Resistance". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/96341549913303846524.
Texto completo國立成功大學
工程科學系專班
98
The manufacturing of an IC electronic device goes through various processes from wafer fabrication to assembly, experiencing different levels of tresses and risks. The final test validates the functionality of each DUT (Device Under Test) in the package form before its shipment. BGA sockets with spring pins acting as an interface between the load board and the DUT during testing are high-price consumables. The quality of sockets determines the yield of the IC testing. However, the performance of a socket decreases with the increasing number of touches and can cost a lot if it is replaced wrongly. Therefore, to get the balance between quality and cost of sockets, a counter embedded in the BGA socket is used to record the number of touches between the pins and solder balls in this study. Thus, wear of the four contact points of the spring pin to the solder ball can be monitored to see its effect on the contact resistance real time. The results show that there is variation in contact resistance even in new pins. Thus, the time of replacing individual pins due to wear varies. The increase in contact resistance is mainly caused by wear and arcing as the number of touches increase. On the other hand, the spring force of individual pins is not significantly affected by the number of touches; namely, the spring force is not a good indicator of pin wearing. A meter system is designed and deployed in this study to monitor the increase in contact resistance so that the socket quality can be assured. Keywords: Device testing, IC socket, Spring pin, Contact resistance
Zhan, Tian-Hao y 詹天皓. "Study on contact resistance of PtSi/poly-Si". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/76918280060200274511.
Texto completoYang, Wen-Lu y 楊文祿. "A study of contact resistance for VLSI metallization". Thesis, 1992. http://ndltd.ncl.edu.tw/handle/42104773117133745180.
Texto completoLin, Tsung-Hsin y 林宗信. "Contact Temperature and Thermal Contact Resistance Based on a Random Cantor Set Surface Model". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/10661054557548262413.
Texto completo國立臺灣大學
機械工程學研究所
96
This paper studies the contact temperature and thermal resistance at the interface of two solids. Two different cases are considered: (1) sliding contact with Coulomb friction and (2) static contact while the two surfaces have different temperatures. When two surfaces are in contact, the load-displacement relationship and the interfacial heat conduction depend on the surface topography as well as the material properties of the contact solids. Most surface models treat the rough surface as a collection of asperities with a fixed shape. The heights of the asperities are distributed stochastically. However, recent studies showed that conventional geometrical parameters used to characterize the shape of the asperities depend on the resolution of the roughness-measuring instrument. This result suggests the use of fractal geometry for the characterization of surface roughness. In this thesis, we construct a random fractal surface model based on the Cantor set. We study the situation where a random Cantor surface is in contact with a rigid insulated smooth surface. Given the probability density functions of the random fractal parameters, we derive the expectations and standard deviations of the applied load, contact temperature, and thermal resistance. Finally, the Monte-Carlo simulation is employed to verify the analytical results.
Hou, Kai-hsiang y 侯凱翔. "Low contact resistance current collectors for lithium ion batteries". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/29zd9t.
Texto completo逢甲大學
材料科學所
100
Current collectors with low contact resistance for lithium ion batteries have been investigated in this thesis. Four types of current collectors, including AISI 304 stainless steel and three types of carbon coated stainless steels, were used for LiMn2O4/LiFePO4 electrodes to perform the capacity under C-rate charge-discharge. The carbon films were deposited on AISI 304 stainless steel by chemical vapor deposition (CVD). The types of carbon films were controlled by concentration of carbon source with C2H2/H2 ratio of 0.15, 0.45 and 1.4, respectively, and CVD reaction temperature of 810 oC. The three types of carbon coating are carbon filament (CF), carbon sphere (CS), and carbon transition (CT, a transition type in-between carbon filament and sphere), respectively, based on those surface morphologies. CT-typed current collector unequivocally demonstrate a remarkable improvement on capacity under all current rates particularly at high C-rate(10C). The CS and CT composed of continuous carbon layers are found to greatly reduce the contact resistance between the electrode layer and the current collector. We also found that the ohmic drop decreases at high rate resulting from carbon layer coating. The overall charge-transfer resistance can be reduced by carbon-coated current collector according the results of Nyquist plots. Therefore, the power performance of Li-ion batteries is enhanced by ~55%.
Khatiwada, Mahesh y 馬哈仕. "Investigation of Thermal Interface Materials to reduce contact resistance". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/esexh4.
Texto completo國立交通大學
機械工程系所
107
Advancement of the modern generation for fast, reliable and small computing devices has led to development of high power density per unit area. Most of this heat is to be dissipated using the various heat sinks. The unevenness or roughness of these surfaces offer the resistance to the flow of heat from the heat source to heat sink. This resistance on the contact due the roughness of the surface known as Thermal Contact Resistance (TCR) has to be minimized for effective heat transfer from heat source to heat sink. Using Thermal Interface Material (TIM) between the contact surfaces has been the effective way to reduce the thermal contact resistance. Decrease of surface roughness significantly reduces the contact resistance. Moreover, study on effect of pressure and surface temperature on TCR was performed. It clearly indicates increase of pressure and temperature decreases TCR. The decrement depends on the TIM used. TCR variation on Thermal cycling loading also depends on the Tim used. Similarly study of variation of power supply has effect on the TCR if the TIM melts on the maximum power. An attempt has been made to address the problem of oozing out when TIM that melts is used.
TUNG, LIN CHIEN y 林建通. "Experimental Study on Thermal Contact Resistance and Contact Pressure of Aluminum Blocks and Aluminum Honeycombs". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/75726918967179720914.
Texto completo大葉大學
機械工程學系碩士班
91
This thesis is divided into two parts: the first part is “Research on Thermal Contact Resistance and Interfacial Pressure of Aluminum Blocks”, and the second part is “Research on Thermal Contact Resistance and Interfacial Pressure of Aluminum Honeycombs”. The first part of this thesis was an experimental study of thermal contact resistance conducted with metallic contacts across bolted joints. Three types of interfaces were considered, including Al/Al, Cu/Al, and SS/Al contacts. The aluminum sample has a square cross section (63.5 mm × 63.5 mm) and a height of 50 mm. The bolt patterns included 4 and 8 bolt configurations. The bolt shaft diameter was 8 mm. The contact pressure of bolted interfaces was measured by the pressure-measuring film through an image processing technique. Results indicate that the contact pressure increases with the torque applied on bolts. The contact pressure also increases with either an increase in the number of bolts, or a decrease in the surface roughness of contacting surfaces. The thermal contact resistance of bolted junctions depends strongly on the interfacial contact pressure. Correlation of interfacial pressure was developed in terms of the torque and bolt-joined parameters. Contact resistance correlation was expressed as a function of the contact pressure, surface roughness, and material properties. Both correlations were in reasonable agreement with the experimental data obtained in this study. The second part of this thesis was to study experimentally the thermal contact resistance and interfacial pressure of aluminum honeycombs. The honeycomb used in this study was made of Al3104-H19. The cell diameters of honeycombs were 6.3 and 12.7 mm. Temperature measurement shows that the temperature drop across the honeycomb sample is lower for the honeycomb with a smaller cell diameter. In order to further investigate the influence of sample heights on contact resistance, the honeycomb samples with two different heights were adopted. Results indicate that the total thermal conductance is higher for samples with a smaller cell diameter. The increase of the number of bolts leads to an increase of the total conductance. The contact resistance between aluminum honeycomb and aluminum alloy sample is about 7% of the total resistance. In addition, the contact resistance of honeycombs with a cell diameter of 6.3 mm decreased with the increasing torque. However, for the honeycombs with a cell diameter of 12.7 mm, the torque and the bolt pattern produce nearly no influence on the thermal contact resistance. The contact resistance is almost independent of the honeycomb height, but the total resistance decreases with increasing the height of samples.
Lin, Tai-Ming y 林泰名. "Development of Ohmic Contacts with Low Surface Roughness and Low Contact Resistance on AlGaN/GaN HEMTs". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/08365759460063234980.
Texto completo國立交通大學
材料科學與工程學系
101
The characteristics of Ohmic contacts on GaN high electron mobility transistors (HEMTs) have profound influence to the DC and RF performance. The most critical issue for Ohmic contacts on GaN HEMTs is the roughness of the surface morphology caused by interdiffusion of metals under high temperature annealing. The rough surface morphology will cause difficulty in E-beam lithography aligner and potential degradation in device performance and reliability. In this study, I optimized the surface morphology of the Ohmic contact on GaN HEMTs with improved barrier layer thickness. The Ti/Al/Ti/Ni/Au (20/120/40/60/50 nm) metal scheme shows a low specific contact resistivity (ρc) of 3.9x10-6Ωcm2 and a smooth surface morphology of 27.6nm root mean square roughness (Rrms) after annealed at 870℃for 35 seconds. This metal scheme is then analyzed by transmission electron microscope (TEM) and X-ray diffractormeter (XRD) to figure out the formation mechanism of it. According to the analytic results, formation of large flat AlNi grains that lay on the TiN stripe rather than surrounded by Al-Au might be the reason for improved surface morphology. With moderate Ti and Ni barrier layer thickness, the formation of Al-based intermetallics could be confined. Moreover, the second Ti layer would form thick TiN above AlGaN that might facilitate the tunneling mechanism of Ohmic contact. Finally, the optimized Ohmic contact was applied to make the HEMT devices, and the DC characteristics are as shown below: VDmax about 490mA/mm at Vg =0V, peak gm about 170mS/mm and VBR larger than 100V.
Shih, Che-Ju y 施哲儒. "A Study on the Nickel Germanide Contacted N+-P Germanium Shallow Junction and Contact Resistance". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75953686017457551375.
Texto completo國立交通大學
電子工程學系 電子研究所
102
In the past several decades, the research on Si-based devices progresses very fast. Furthermore, the Si-based MOSFETs have been successfully scaled down to 20 nm regime. However, scaling down the devices becomes more and more difficult and reaches the physics limits soon. Therefore, developing another ways to promote the device performance is necessary. Using new semiconducting materials is a way to improve performance. Because germanium has higher mobility and process compatibility for MOSFET fabrication process, germanium is considered to replace Si as the channel material in the future. Nevertheless, the n-type dopant diffusion in germanium is fast so that it is not easy to form shallow n+/p junction, and the high Schottky barrier height at the metal/n-Ge interface causes a high contact resistance due to the Fermi level pinning near the Ge valance band at the interface between metal and germanium. Therefore, the thesis would focus on the forming of shallow n+/p-Ge junction and low resistance metal/n-Ge contact. Because NiGe has the lowest resistivity and low temperature formation, NiGe is selected as the contact metal. The implantation before germanide (IBG) process means ion implantation is performed before germanide formation, and the implantation after germanide (IAG) process means ion implantation is performed after germanide formation. For the IBG junctions fabricated on heavily-doped substrate, very poor junction characteristic is observed by high dose phosphorous ion implantation due to the fast diffusion of Ni by virtue of defects which are generated by ion implantation. Fluorine ion implantation before NiGe formation could effectively suppress Ni diffusion and reduce the leakage current. Moreover, better junction characteristic can be obtained by low dose ion implantation due to the less defects resulting in less Ni diffusion. However, fluorine implantation before NiGe formation would enhance the Ni diffusion to degrade junction characteristic because the fluorine ion implantation induces extra defects. Next, on the lightly-doped substrate, good junction characteristic is more easily to be obtained than on heavily-doped substrate because the deeper junction depth on lightly-doped substrate so that the Ni diffusion would not destroy the junctions. In particular, after NiGe formation, the forward current obviously increases owing to the dopant segregation at the NiGe/Ge interface. Furthermore, either phosphorous or arsenic n+/p junction would have the dopant segregation effect. The arsenic n+/p junctions have relatively low activation concentration inferred by the I-V characteristic. Finally, because the IAG junctions have poor junction characteristic due to the segregated n+ layer is too thin to maintain good n-p junction and the Ni fast diffusion induces large leakage current, the IBG+IAG process is proposed. The IBG+IAG junction could achieve shallow junction depth and raise the forward current at the same time. Furthermore, the measured contact resistance of the IBG junction is about 2x10-5 -cm2 and the lowest contact resistance of IBG+IAG junction is 2x10-6 -cm2.Therefore, this thesis has formed a junction with shallower junction depth, lower leakage current, and lower contact resistance in comparison with previous studies. This achievement is expected to improve the performance of Ge nMOSFETs.
黃惟孝. "Measurement and failure analysis of wafer probe testing contact resistance". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/09657629533550316724.
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