In order to evaluate the feasibility of forming Pure Mg – Pure Mg and Mg Alloy – Mg Alloy joints using soldering and brazing, four filler metals (Sn, Sn-9Zn, Sn-9Zn+X wt%Mg and Mg:Zn:X(Sn-9Zn)) were used at peak heating temperatures of ~250°C, 350°C and 450°C. Differential Scanning Calorimetry (DSC) and microstructure characterization were used to evaluate the successful joints. When using Sn as a filler metal, a joint forms, at temperatures as low as 235°C, which consists of a Mg-Sn eutectic filler layer and a continuous Mg2Sn intermetallic layer at the filler metal/Mg interface. This joint microstructure persists up to peak temperatures of 350°C and 450°C. The main effect of increasing the peak temperature causes an increase in the thickness of the Mg2Sn layer. Joints formed using Sn-9Zn prealloyed filler metal, developed a filler metal composition according to a Sn rich Mg-Sn-Zn ternary microstructure. A continuous Mg2Sn layer still formed in the joint. Ternary phase diagram predictions support the development of a number of MgxZny intermetallic compounds. However, only isolated experimental evidence of Mg-Zn liquid formation was present at peak heating temperature of 350°C and no evidence of MgxZny intermetallic layers was observed for both base metal systems using Sn-9Zn filler metal at 250°C and 350°C. Upon further heating above 350°C, a Mg7Zn3 layer forms which eventually leads to a Mg-Zn eutectic liquid formation as 450°C is reached. Wide gap Transient Liquid Phase Bonding (TLPB) was carried out by adding Mg to Sn-9Zn filler metal. Decrease in liquid volume fraction during solidification was noted with increase in Mg wt% as well as an increase in heating temperatures. Complete consumption of the filler metal was observed at 30wt% Mg and 450°C. Microstructural events were noted to be similar to Mg-Mg couples using Sn-9Zn filler metal. Mg-Zn, 50:50 wt% filler metal was thus used to evaluate joints without Mg2Sn intermetallic formation. Mg-Zn binary liquid phase formation was found to correspond to 342°C upon initial heating and presence of solid Mg7Zn3 in microstructure was found in samples heated to 350°C. Increase in diffusional solidification of Zn into the unreacted Mg powder and Mg base metal was noticed upon further heating to 450°C. Significant influence on the microstructure was noticed with addition of prealloyed Sn-9Zn powder to Mg-Zn filler metal mixture. Sn-9Zn was observed to be consumed in solid state during initial heating while alloying and dissolution of Pure Mg particles was seen to be accelerated. All Pure Mg powder was consumed indicating a large volume fraction present at 450°C in the case of filler containing 10% Sn-9Zn. The primary cellular grains of (Mg) grow from the Mg base metal substrate and Mg7Zn3 solidifies in the intercellular region. In the original filler metal portion of the diffusion couple, a mixture of (Mg), Mg7Zn3 and eutectic appears with a more dispersed character indicative of an equiaxed growth process. Promising results from 45Mg:45Zn:10(Sn-9Zn) wt% and peak heating temperature of 450°C could form basis for future work which can eventually lead to a commercial application.

Electronic devices such as high power devices, microprocessors and memories in integrated circuit are primarily composed of metal-oxide-semiconductor field effect transistors (MOSFETs), due to the advantages of low cost, low power consumption and easy to scale down. However, the aggressively scaled conventional MOS devices have suffered remarkable short channel effects such as drain induced barrier lowering, punch-through, and direct-tunneling gate leakage. These problems not only lower the gate controllability but also increase the standby power consumption. Because the SiO2 dielectric and poly-gate are improper for CMOS application below 45 nm technology node due to the critical gate leakage current. Therefore, we investigate the electrical characteristics and physical mechanisms of MOSFETs with HfO2/TixN1-x gate stacks by using split C-V, pulsed Id-Vg, and charge-pumping techniques. The experimental results indicate that dynamic stress is more serious than static stress, and hot-carrier effect corresponding to different gate stress biases demonstrate distinct dominant degradation behaviors and the charge-trapping phenomenon. Furthermore, different concentration of titanium in TiN metal gate significantly affect device characteristics associated with the amount of nitrogen diffusion from the metal gate to high-k bulk and the SiO2/Si interface layer.

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The polydentate ligands containing both thiolato and phosphino groups have been used in catalysis and enzyme mimetic studies. We have synthesized two tetradentate thiophosphine ligands : tris(2-thiophenyl)- phosphine¡]H3L1¡^ and tris(3-trimethylsilyl-2-thiophenyl)phosphine (H3L3) and one tridentate thiophosphine ligand (bis(2-thiophenyl)- phenylphosphine¡]H2L2¡^. These ligands formed a series of germanium and tin metal complexes. We are thus exploring a range of syntheses of tin and germanium complexes. The ligand H3L1 react with SnCl4 to give trimeric tin units with bridging methoxyl group and oxo group. The ligand H2L2 react with SnCl4 or GeCl4 to give ML2 type complexes. H3L3 with germanium and tin metal complexes were synthesized and characterised by NMR spectra and mass spectra. We also obtained crystal structure of complexes GeCl(L3) and GeEt(L3). The structure was trigonal bipyramidal.

Abstract A thin film deposition system using ultrasonic atomization is designed and constructed. Solution containing precursors is transported by carrying gas to the heated substrate where deposition is accomplished by pyrolysis. Tests including series of varying flow rate of carrying gas and varying substrate temperature were carried out with solutions of SnCl4 precursor in C2H5OH solvent and N2 as carrying gas. Also, TaCl5 was used as dopant to improved the electrical conductivity. The effects of doping in crystallinity, surface morphology, optical transmittance and electrical conductivity of the deposited thin films were examined and the optimal percentage of doping for electrical conductivity and optical transmittance was found. XRD reveals that the thin film was amorphous when the deposition temperature was below 350¢J. Polycrystalline thin films with grains size of 30~50nm were obtained with deposition temperature of 400~500¢J and N2 flow rate of 2.5 ~10 l/min. SEM examination reveals that porosity increases with increasing deposition temperature and N2 flow rate, which consequently reduces the electron mobility, as seen in Hall measurement. No discernible difference was observed between the morphology of the doped and undoped thin films. As shown in the UV-Visible spectra representative transmittance of all films at 550nm radiation ranges between 70% and 82%. No discernible effect was observed for Ta-doping. Hall measurement reveals that Ta-doping increases the electron mobility and carrier concentration by several times and one order of magnitude, respectively. The minimum resistivity is 1.2*10-1 £[- cm occurring at 4 at% Ta doping.

Current requirements of nonvolatile memory (NVM) are the high density cells, low-power consumption, high-speed operation and good reliability for the scaling down devices. However, all of the charges stored in the floating gate will leak into the substrate if the tunnel oxide has a leakage path in the conventional NVMs. Therefore, the tunnel oxide thickness is difficult to scale down in terms of charge retention and endurance. The nanocrystal nonvolatile memories are one of promising substitution, because the discrete storage nodes as the charge storage media have been effectively improve data retention under endurance test for the scaling down device. Many methods have been developed recently for the formation of nanocrystals. Generally, most methods need thermal treatment with high temperature and long duration. This procedure will influence thermal budget and throughput in current manufacture technology of semiconductor industry. And supercritical carbon dioxide (SCCO2) has been researched to the passivation of dielectric and reducing the activation energy. The research estimates SCCO2 is potential to form nanocrystals for these reason. This research is to discuss the feasibility of fabricating nanocrystal NVMs device with low temperature SCCO2. The low melting point metal material Sn is used for the attempts. In order to check if Sn can be used for fabricating nanocrystal NVMs device, the research selects the conventional thermal annealing method first. It uses rapid thermal annealing to improve the crystalline of nanocrystals and reliability of the memory device. Compare to different Sn containment or chemistry and different process, analyze the electric characteristics and materials chemistry. At last, select the Sn and SiO2 co-sputtering film to try the SCCO2 process and analyze these characteristics as well. Due to the novel technology, many physical mechanism and improvement of properties will be discuss following.

This dissertation has focused on the study of the ITO/organic heterojunction and the chemistries therein, it proposes appropriate strategies that enhance the interfacial physical and electronic properties for charge injection with application to organic thin-layer devices. We focused on four major aspects of this work: i) To characterize the ITO surface and chemistries that may be pertinent to interaction with adjacent organic layers in a device configuration. This developed a working model of surface and provided a foundation for modification strategies. Characterization of the electronic properties of the surface indicate less than 5% of the geometrical surface is responsible for the bulk of current flow while the rest is electrically inactive. ii) To determine the extent to which these chemistries are variable and propose circumstances where compositional changes can occur. It is shown that the surface chemistry of ITO is heterogeneous and possible very dynamic with respect to the surrounding environment. iii) To propose a strategy for modification of the interface. Modification of ITO surfaces by small molecules containing carboxylic acid functionalities is investigated. Enhancements in the electron transfer rate coefficient were realized after modification of the ITO electrode. The enhancements are found to stem from a light etching mechanism. Additionally, an elecro-catalytic effect was observed with some of the modifiers. iv) Apply these modifications to organic light emitting diodes (OLEDs) and organic photovoltaic devices (OPVs). Enhancements seen in solution electrochemical experiments are indicative of the enhancements seen for solid state devices. Modifications resulted in substantially lower leakage currents (3 orders of magnitude in some cases) as well as nearly doubling the efficiency.An additional chapter describes the creation and characterization of electrochemically grown polymer nano-structures based on blazed angle diffraction gratings. The discussion details the micro-contact printing process and the electro-catalytic growth of the conductive polymers PANI and PEDOT to form diffraction grating structures in their own right. The resulting diffraction efficiency of these structures is shown to be sensitive to environmental conditions outlining possible uses as chemical sensors. This is demonstrated by utilizing these structures as working pH and potentiometric sensors based on the changing diffraction efficiency.

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