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<p> The static electrical characteristics of dual-gate silicon n-channel insulated-gate field-effect trapsistors are investigated experimentally. A mathematical model based on theoretical expressions and containing twelve parameters adjusted for. best fit was developed. </p> <p> The mathematical model was used to calculate the low frequency conversion transconductance as a function of operating conditions. </p> / Thesis / Master of Engineering (MEngr)

The main objective of this work is to develop and optimize a process for the fabrication of basic semiconductor devices in silicon using the Modu-lab toolset in the MicrON 636 Whittemore cleanroom facility. This toolset is designed to work with four-inch silicon wafers, in a class 10000 cleanroom. Early work on this process produced functioning devices, with low yield and little to no process control. Three aspects of the process were therefore selected for optimization in this work. The oxidation of the surface of the silicon wafers could not be made to follow models proposed by and accepted in the literature. By carefully changing the airflow in the oxidation furnace module, the uniformity of the oxide layer and the agreement of the growth with models increases to acceptable levels. Also, the effects of redistribution of dopant species due to growth of the oxide layer and the subsequent thermal processing are examined qualitatively. Phosphorus diffusion in single-crystal silicon has a complex diffusion mechanism involving charged-vacancies, with concentration-dependent diffusion coefficients. It is therefore a complex mathematical problem to model the diffusion of phosphorus from a solid source within the crystal. An empirical model is proposed that accurately predicts the junction depth and sheet resistance of diffused phosphorus layers within the silicon wafer. Throughout the course of the process it is necessary to monitor the characteristics of the wafers to assure proper conditions. A semiconductor parameter analyzer has been created for this purpose. Our system uses a Keithley model 2400 source meter, Signatone probe station and four-point probe stage, and a PC to measure DC I-V electrical characteristics of materials and devices. The measurements of sheet resistance, as well as device characterization of resistors, p-n junction diodes, and nMOSFETs provides feedback about the accuracy of processing steps, as well as a pedagogical tool for illustrating semiconductor device physics and operation. / Master of Science

No / Nanotechnologies for intracellular delivery are of great value in clinical and biological research. Diamond nanoneedle arrays are a novel and attractive platform to facilitate drug delivery with minimal cytotoxicity. Using our technique, the cellular membranes can be temporarily disrupted for enhanced diffusion of drug molecules to cytoplasm. Herein we show that this technique is applicable to deliver different types of anticancer drugs into a variety of cell lines, although the membrane of each cell line possesses varied rigidity and hardness and each drug has its own unique properties and targets. When anticancer drugs and nanoneedle arrays are collaboratively used to treat cancer cells, the cell viability dramatically decreases by up to 40 % in comparison with the cells treated with drugs only. Attractively, therapeutic molecules can be efficiently delivered to drug-resistant cells with the aid of nanoneedle arrays. The combination of diamond nanoneedle arrays and anticancer drug cisplatin can decrease the viability of A549 cisplatin-resistant cells to about 60 %, while the cells only treated with the same concentration of drug are essentially not affected due to their drug resistance. These results indicate that dense nanoneedle arrays represent an effective approach to enhance the delivery of biological molecules to different types of cells. Such approach will certainly be beneficial to microbiological research and clinical applications in the future.

The adhesion durability of coatings and encapsulant materials utilized in electronic packaging is vital for device reliability in the microelectronics industry. Due to adverse operating conditions such as high moisture and high temperature environments, the adhesion between an adhesive and its substrate is typically compromised. This thesis addresses the advantages of employing plasma pretreatments and surface derivatization using silane coupling agents as surface modification techniques in an effort to enhance the adhesive bonding of epoxy to SiC coated Si wafers (SiC/Si). Durability was evaluated by immersing coated-Si samples in aqueous solutions at elevated temperature (60°C) to simulate prolonged severe operating conditions. Three surface modification approaches for the SiC/Si substrate to be discussed include: 1) a silane coupling agent treatment, which involves a reaction of either 3-aminopropyltriethoxysilane (APS) or 3-glycidoxypropyltrimethoxysilane (GPS) with the substrate, 2) an oxygen plasma pretreatment followed by a silane treatment, and 3) a water/oxygen plasma pretreatment followed by a silane treatment. Samples were immersed in aqueous solutions at various pH at 60°C for extended periods of time. Adhesion durability of treated epoxy/SiC/Si systems was qualitatively evaluated by visual inspection for debonding, and quantitatively evaluated using a probe test to evaluate the critical strain energy release rate G_c. Additionally, X-ray photoelectron spectroscopy (XPS) surface characterization was carried out following the surface treatments and again after complete failure in the durability tests. The durability tests illustrated that surface treatments involving an oxygen plasma pretreatment prior to silane derivatization resulted in significant improvement in adhesive performance. Furthermore, the results of XPS analysis suggested that the improved bonding was due to cleaning of the substrate surface, promotion of silane adsorption and the formation of a thicker oxide layer. The effectiveness of the surface modification methods in relationship to surface chemistry and adhesion for the epoxy/SiC/Si system is reported and discussed in this work. / Master of Science

Silicon nitride (Si3N4) is a potentially good ceramic material for industrial heat exchangers. However, at elevated temperatures and in coal combustion atmospheres its lifetime is severely reduced by oxidation. To increase its corrosion resistance, the formation of a protective oxidation barrier layer was promoted by the deposition of oxide thin films. Homogeneous and crack-free oxide coatings of calcium magnesium zirconium phosphate (CMZP) and magnesium doped aluminum titanate (Mg-doped Al2TiO5) were successfully deposited on Si3N4 using the sol-gel and dip-coating technique. Coated and uncoated samples were then exposed to a sodium containing atmosphere at 1000*C for 360 hours to simulate typical industrial environment conditions. Structural post-exposure analyses based on weight loss measurements and mechanical tests indicated better corrosion resistance and strength retention for CMZP coated Si3N4 compared to as received and Mg-doped Al2TiO5 coated Si3N4. This difference was attributed to the protective nature of the corrosion layer, which in the case of CMZP, significantly impeded the inward diffusion of oxygen to the Si3N4 surface. / Master of Science

Finally, we also propose and demonstrate an integrated Mach-Zehnder optical diplexer (IMZOD) for possible use in an integrated silicon optical amplifier. The diplexer is based on two rnultimode interferometers (MMIs) and a Mach-Zehnder interferometer (MZI), and has potential use in an integrated silicon waveguide optical amplifier, to combine or separate the pump signal (1440nm) and probe signal (1556nm) for monolithic implementation of a silicon Raman amplifier. / Helium ion implantation can not only reduce the free-carrier loss, but can also enhance the detection responsivity of below-bandgap wavelengths (1440 1590 nm). We propose and demonstrate an in-line channel power monitor (ICPM) based on helium ion implanted silicon waveguides. The implanted waveguide can detect light at 1440 1590 nm which are normally not detectable by silicon. We study the enhanced photoresponse of helium ion implanted waveguide samples which were annealed at different temperatures and for different durations. / Recently there has been much interest in silicon optical amplifiers and lasers relying on stimulated Raman scattering (SRS), which, despite the much shorter waveguide lengths possible in silicon compared with silica optical fiber, can still provide large optical gain because of the large Raman coefficient of silicon and small mode field areas. However, two-photon absorption (TPA) generated free-carrier absorption (FCA) loss can exceed the Raman gain. In this thesis, experiments and theoretical model will he discussed and analyzed, showing that helium ion implantation can successfully reduce the optical losses due to free-carriers and allow net gain to be attained by continuous-wave (CW)-pumped SRS without requiring external bias to remove the photo-generated free carriers. The theoretical study of dynamics of free carrier lifetime of the silicon waveguides will be described. The effective nonlinear length of the silicon waveguides is defined and studied. The theoretical and experimental studies of the enhanced spectral broaden induced by self-phase-modulation (SPM) are carried out in helium on implanted silicon waveguides. / Silicon-on-insulator (SOI) wafers are an attractive platform for the fabrication of planar lightwave circuits (PLCs) because they offer the potential for low-cost fabrication using mature complementary metal--organic--semiconductor (CMOS) compatible processes developed in the microelectronics industry. At the wavelengths of interest for telecommunications, SOI waveguides can have low optical losses (0.1dB/cm). Besides, the strong optical confinement offered by the high index contrast between silicon (Si) (n=3.45) and silicon dioxide (SiO2) (n=1.45) makes it possible to scale photonic devices to sub-micron level. In addition, the high optical intensity arising from the strong optical confinement inside the waveguide makes it possible to observe nonlinear optical effects, such as Raman and Kerr effects, in chip-scale devices. / We then make use of the ICPM to perform a system application, called optical-burst-and-transient-equalizer (OBTE). The OBTE may provide a compact and low-cost solution to compensate gain-transient, gain-spectrum-tilt and to equalize the upstream packet amplitude in erbium doped fiber amplifier (EDFA) amplified hybrid dense-wavelength-division-multiplexed (DWDM) and time-division-multiplexed (TDM) passive-optical-networks (PONs). The OBTE may be monolithically integrated on SOI platform and is potentially low cost and compact. The OBTE can compensate complicated gain slope shape, which may be generated in cascaded EDFAs or deliberate channel add/drop, based on individual channel equalization. 15-dB receiver sensitivity improvement at 10 Gbit/s bit-error-rate (BER) measurements of 10-9 was achieved by the compensation. / Liu, Yang. / "August 2007." / Adviser: Hon Ki Tsang. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1212. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Cette thèse est consacrée au silicium polymorphe hydrogéné (pm-Si:H). Elle porte tout d'abord sur une étude du pm-Si :H puis sur une étude des cellules photovoltaïques fabriquées à partir de ce matériau. Le pm-Si:H est formé de couches minces nanostructurées et peut être déposé par PECVD conventionnelle. Les effets des différents paramètres de dépôt (mélanges gazeux, pression, puissance RF, température du substrat) sur les propriétés du matériau ont été étudiés pour optimiser sa qualité. La caractérisation des couches a été un enjeu primordial. Pour cela, nous avons choisi de combiner une palette très large de méthodes de caractérisation (ellipsomètrie spectroscopique, exodiffusion d'hydrogène, SIMS, FTIR, AFM, etc...). A cause de la contribution des nanoparticules de silicium dans le plasma, la nature du dépôt du pm-Si:H montre la différence contrairement au a-Si:H pour lequel le dépôt se fait par le biais de radicaux ionisés. L'étude des conditions du procédé nous a conduit à fabriquer des cellules solaires d'un rendement initial de 9.22 % avec un facteur de forme élevé (74.1), mais aussi de démontrer des effets de vieillissement inhabituels, tels que i) une dégradation initiale rapide, ii) une dégradation irréversible, et iii) de grands changements structuraux macroscopiques. Nous avons découvert que le principal problème se situe entre le substrat et la couche mince de silicium. L'hydrogène moléculaire diffuse et s'accumule à l'interface entre le substrat et la couche mince, ce qui introduit un délaminage local qui a pour conséquence une dégradation initiale rapide des performances des cellules. Nous avons trouvé que sous éclairement une structure PIN facilite l'accumulation d'hydrogène et le délaminage à l'interface entre le substrat et la couche dopée p. Cependant, l'utilisation d'une structure NIP empêche l'accumulation d'hydrogène et le délaminage. Cela nous a permis de fabriquer des cellules solaires pm-Si:H de structure NIP d'un rendement stable de 8.43 %, mais aussi de démontrer une degradation minimale (10 %) après un vieillissement de 500 heures.