Author: Yongseok Jun
Publisher:
ISBN:
Category :
Languages : en
Pages : 336

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Author: Yongseok Jun
Publisher:
ISBN:
Category :
Languages : en
Pages : 306

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Author: Ronald Louis Cicero
Publisher:
ISBN:
Category :
Languages : en
Pages : 240

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Author: Michel Rosso.
Publisher:
ISBN: 9789085853794
Category :
Languages : en
Pages : 221

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Author: Austin Woohyuk Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 164

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Book Description
Microwave radiation was utilized as a tool to modify surface properties of silicon oxides. Covalent surface modification of silicon oxides has been widely pursued in the areas of material science, electronics, microfluidics, biology, and separation science. Chemical surface modifications are often achieved through the formation of organic monolayers, often referred to as self-assembled monolayers (SAMs). While these organic monolayers have been proposed as an effective surface modification strategy, the defects in these organic monolayers compromise the effectiveness on their ability to alter surface properties. For example, in the case of passivation of microscale electronic devices, the surfaces that are not covered by the organic monolayers are susceptible to environmental stress or corrosion, which can cause detrimental failures of the devices. Traditional methods of formation of monolayers often cause many defects including formation of multilayers or micelles, physically adsorbed organic film, and/or voids. In this thesis, microwave radiation is utilized as a tool to accelerate the formation of uniform monolayers. In particular, the formation of silane based monolayers and alcohol based monolayers on silicon oxide surfaces have been extensively studied. Microwave heating, unlike the traditional heating methods, delivers the thermal energy to the substrate surfaces. It can effectively accelerate the formation of both silane and alcohol based monolayers. Alcohol based reagents, in particular, is proposed as an alternative building blocks for their widespread availability and minimal reactivity with moisture. Tuning of surface chemistry of silicon oxides have been achieved with alcohol based regents with different functional groups. Furthermore, the formation of mixed monolayers has been proposed as means of controlling oleophobicity of the silicon oxide surfaces. Finally, the film thickness of the alcohol based monolayers has been characterized with angle-resolved X-ray photoelectron spectroscopy (ARXPS). The film thickness can be precisely tuned by choosing the alcohol based reactants with particular lengths of alkyl chains. A variety of surface chemistry can be designed towards many practical applications requiring surface functionalized silicon oxides using the research presented herein.

Author: Ryan Charles Major
Publisher:
ISBN:
Category :
Languages : en
Pages : 308

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Author: Abraham Vega Zendejas
Publisher:
ISBN:
Category : Atomic layer deposition
Languages : en
Pages : 186

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Silicon remains the most important material for a host of applications including electronics, sensors, and even energy. Consequently, the modification of its surfaces and the ability to integrate other materials by thin film deposition are important. This proposal addresses two specific issues to help control these important processes. The first is the grafting of organic molecules and the subsequent use of these self-assembled monolayers to attempt to obtain shallow doping in silicon. This constitutes a novel approach that needs to be demonstrated and tested. The second is the deposition (or growth) of molybdenum nitride and molybdenum oxide films and the understanding of the mechanism behind that growth. There appears to be an urgent need in the industrial community for such films, given the versatility and the wide range of applications this compounds can provide. This work addresses the growth and characterization of these films, working closely with precursor providers to achieve this goal.

Author: Louis C. P. M. de Smet
Publisher:
ISBN: 9789085043676
Category :
Languages : en
Pages : 174

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Author: Jing Zhao
Publisher:
ISBN: 9780355734959
Category :
Languages : en
Pages : 116

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Silicon and metal surfaces modified with organic molecule precursors are of great importance to the semiconductor and electronics industries. However, it is always a challenge to choose the most efficient precursors for forming a monolayer with surfaces and to investigate the chemical changes on surfaces by controlling critical conditions, such as surface temperature. In order to obtain a better understanding of the reactions between organic molecules and surfaces, we combined experimental results including infrared spectroscopy (IR), temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and microscopic studies together with density functional theory (DFT) studies. For silicon surface studies, we focused on determining the reaction step that plays the key role in halide precursors sticking probabilities and the influence of temperature on the formed monolayer. For metal surface studies, we focused on the etching method to control the layer thickness of thin metal films. ☐ During the process of achieving a halide-terminated Si (100) surface in ultrahigh vacuum (UHV), we compared the sticking probabilities of ethyl-chloride and ethyl-iodide reacting with a clean Si (100) surface using TPD and DFT studies. It has been demonstrated that the weakly bound precursor states of ethyl-halide on surfaces determines the sticking probabilities during adsorption. At the same time, we applied multivariate curve resolution (MCR), a mathematical method to simplify interpreting the complex TPD spectra resulting from the low sticking probability of ethyl-chloride adsorbing on silicon surfaces. ☐ In addition to halide-terminated Si (100) surfaces, amine-terminated Si (100) surfaces are reactive and potential for further modification. We studied the adsorption of triethylenediamine (TEDA) on a clean Si (100) surface as well as the adsorbents while varying temperature. The experimental techniques including IR, TPD, XPS and angular dependent near-edge X-Ray adsorption fine structure (NEXAFS) were supplemented by DFT calculations. We concluded that the adsorption process can be controlled by temperature: a datively bonded TEDA-Si-Si complex forms on the surface at room temperature as well as at cryogenic temperature with low exposure; heating above 400 K leads to C-N dissociation and ultimately the formation of surface nitride and carbide species. ☐ A thermal dry etching process of cobalt thin films was investigated using 1, 1, 1, 5, 5, 5 -hexafluoro-2, 4-pentanedione (hfacH). The chemical species resulting from thermal treatment were studied by IR, TPD, and XPS. The topography and morphology of the surfaces were investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results indicated that the etching of cobalt can occur Hhfac, but not with halogens.

Author: Yekaterina Leonidovna Lyubarskaya
Publisher:
ISBN:
Category :
Languages : en
Pages : 178

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"The research presented in this dissertation focuses on the study of self-assembled monolayers (SAMs) in the modification of surface properties of different substrates for various applications. Self-assembled monolayers are organic molecules that can be deposited on a variety of surfaces, such as those of metals, metal-oxides, and semiconductors. Formation of SAMs on any inorganic material provides a ubiquitous way to impart desirable chemical and physical properties of organic and biological molecules to the inorganic substrate. It has been demonstrated that single molecules and their self-assembled monolayers can significantly alter the physical and electronic properties of inorganic conductors; moreover, studies have shown that the performance of many electrical devices can be transformed by modifying inorganic electrodes with organic SAMs. This is especially important for the development of next generation of ultra-compact electronic devices, in which the ability to control the interfacial charge-transport with a single monolayer of organic molecules would be ideal. We have developed different organic electronic architectures as test beds for studying the effect of monolayer properties, such as structural and geometrical parameters, on their electronic properties. By using a typical organic electronic device as a sensitive test platform, slight changes in a monolayer property, such as length, have been detected by studying the current- voltage characteristics (JV) of organic diodes functionalized with self-assembled monolayers (SAMs) of varying alkyl chain-length. Next, we describe the application of SAMs based on n-octylphosphonic acid (C8PA) and 1H,1H,2H,2H-perfluorooctanephosphonic acid (PFOPA) as anode buffer layers in C60-based organic photovoltaic (OPV) devices. We used the OPV platform to compare stabilities of organic monolayers exposed to ambient conditions with SAMs positioned inside working OPV devices. We found that the stabilities are different, suggesting the degradation mechanisms are distinct. The degradation of the OPV efficiency with respect to air exposure was significantly reduced with the perfluorinated PFOPA compared to the aliphatic C8PA. We attributed the OPV degradation to moisture diffusion from the top aluminum electrode and we discuss that the lowering of the anode work function is the result of hydrolysis of the SAM buffer layer. Next, we demonstrated the dependence of molecular electronic properties on the functional group substitution and that the changes in these properties can be measured using the organic light-emitting (OLED) platform. Specifically, we compared bilayered organic monomolecular systems immobilized on an inorganic electrode as the charge-injecting components of the organic light emitting diodes (OLEDs). Our bilayered interfaces comprise ordered inert primary and functional reactive layers, and they differ in only one parameter: the molecular structure of the terminal functional group. We demonstrate that we can visualize the differences in the charge transfer dynamics of two bilayered systems via patterned electroluminescence. In addition, we describe a new protocol for the preparation of shape-controlled multicomponent particles comprising metallic (Au and Ti), magnetic (Ni), and oxide (SiO2, TiO2) layers. First, we discuss the application and attractiveness of the colloidal structures, Janus Particles (JPs), that possess two different surfaces, varying either in polarity, hydrophilicity, etc. Next, we present our method for specifically controlling the composition, shape, and size of the micro-JPs. We demonstrate how this protocol permits fabrication of non-symmetrical particles by orthogonally functionalizing their opposite sides using well-established organosilanes and thiol chemistries (based on SAMs). We propose that these colloids may be used as convenient materials for studying non-symmetrical self-assembly at the meso- and micro-scales, due to their unique geometries and surface chemistries"--Pages viii-x.