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Electron transport in nanoparticle single-electron transistors (SETs) is a fruitful method to explore a wide range of physical phenomena at the nanometer scale. In this thesis, we investigate electron transport in SETs incorporating various nanoparticles, including gold nanoparticles in both classical and quantum regimes and Pb nanoparticle in both superconducting and normal states. SETs have been successfully fabricated by incorporating individual gold nanoparticles into the gaps between two electrodes. Although single-electron tunneling behavior is prominent, quantized energy levels cannot be resolved in these SETs due to their relatively large particle sizes. A novel method has been developed to achieve SETs incorporating gold nanoparticles whose sizes are small enough to resolve discrete quantum energy levels. The devices consist of spontaneously-formed ultrasmall gold nanoparticles linked by alkanedithiols to gold electrodes. The devices reproducibly exhibit addition energies of a few hundred meV, which enables the observation of single electron tunneling at room temperature. At low temperatures, resonant tunneling through discrete energy levels in the Au nanoparticles is observed, which is accompanied by the excitations of molecular vibrations at large bias voltage. Having explored the SETs in normal state, we have extended the experiments to superconducting single-electron transistors (SSETs). We first fabricated and characterized Pb superconducting electrodes with nanometer-sized separation. Our observation clearly shows that conventional Barden-Cooper-Schrieffer theory remains valid to interpret the tunneling behavior between two nanometer-spaced Pb electrodes. Furthermore, by incorporating Pb nanoparticles between the two Pb electrodes, we have fabricated SSETs and investigated the transport properties of these devices. In the superconducting state, the conductance is suppressed by a combination of the single electron tunneling effect and the absence of density of states within the superconducting gap. In the suppression regime, the tunneling spectroscopy shows current features that arise from quasiparticle tunneling caused by singularity matching. At low temperature, the features can only be observed for odd charge states in SSETs. At high temperature, the odd-even parity effect is smeared out. Upon application of a magnetic field, the superconducting state is suppressed and single-electron tunneling behavior for normal metallic nanoparticles is recovered.

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Two MOS-Bipolar composite power semiconductor switching devices are proposed and experimentally demonstrated. These devices feature high voltage and high current capabilities, fast switching speeds, simple gate drive requirements, savings in chip area, reverse bias second breakdown ruggedness and large safe operating areas. Application characteristics of the devices for high frequency power inverter circuits are discussed. Monolithic integration of the two composite devices are also proposed. / Ph. D.

The objective of this thesis is to provide an initial demonstration of the feasibility of constructing highly transparent active electronic devices. Such a demonstration is successfully achieved in the fabrication of ZnO-based thin film transistors (TFTs) exhibiting transparency greater than ~90% in the visible portion of the electromagnetic spectrum and prototypical n-channel, enhancement mode TFT characteristics. Electrical characterization studies of these ZnO-based transparent TFTs and of CuYO��� / ZnO / ITO p-i-n heterojunction diodes serve to elucidate the mechanisms responsible for the behavior of these devices in particular, and of transparent electronic devices in general. Energy band analysis of the degenerate semiconductor / insulator heterojunction yields insight into the phenomenon of charge injection into an insulator, with important implications for the analysis of devices containing heterojunctions of this nature. Finally, a novel technique for simultaneously characterizing carrier injection into an insulator and interface channel formation, the capacitance-(voltage, frequency) [C-(V,f)] technique, is proposed and employed in the characterization of ZnO-based TFT structures. / Graduation date: 2003

Fabrication techniques and process integration considerations for amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) constitute the central theme of this dissertation. Within this theme three primary areas of focus are pursued. The first focus involves formulating a general framework for assessing passivation. Avoiding formation of an undesirable backside accumulation layer in an AOS bottom-gate TFT is accomplished by (i) choosing a passivation layer in which the charge neutrality level is aligned with (ideal case) or higher in energy than that of the semiconductor channel layer charge neutrality level, and (ii) depositing the passivation layer in such a manner that a negligible density of oxygen vacancies are present at the channel-passivation layer interface. Two AOS TFT passivation schemes are explored. Sputter-deposited zinc tin silicon oxide (ZTSO) appears promising for suppressing the effects of negative bias illumination stress (NBIS) with respect to ZTO and IGZO TFTs. Solution-deposited silicon dioxide is used as a barrier layer to subsequent PECVD silicon dioxide deposition, yielding ZTO TFT transfer curves showing that the dual-layer passivation process does not significantly alter ZTO TFT electrical characteristics. The second focus involves creating an adaptable back-end process compatible with flexible substrates. A detailed list of possible via formation techniques is presented with particular focus on non-traditional and adaptable techniques. Two of the discussed methods, "hydrophobic surface treatment" and "printed local insulator," are demonstrated and proven effective. The third focus is printing AOS TFT channel layers in order to create an adaptable and additive front-end integrated circuit fabrication scheme. Printed zinc indium aluminum oxide (ZIAO) and indium gallium zinc oxide (IGZO) channel layers are demonstrated using a SonoPlot piezoelectric printing system. Finally, challenges associated with printing electronic materials are discussed. Organic-based solutions are easier to print due to their ability to "stick" to the substrate and form well-defined patterns, but have poor electrical characteristics due to the weakness of organic bonds. Inorganic aqueous-based solutions demonstrate good electrical performance when deposited by spin coating, but are difficult to print because precise control of a substrate's hydrophillic/hydrophobic nature is required. However, precise control is difficult to achieve, since aqueous-based solutions either spread out or ball up on the substrate surface. Thickness control of any printed solution is always problematic due to surface wetting and the elliptical thickness profile of a dispensed solution. / Graduation date: 2013

This work investigates the effects of post-fabrication applied mechanical tensile strain on Silicon (Si) Bipolar Junction Transistor (BJT) and Silicon-Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) devices. Applied strain effects on MOSFET transistors are being heavily explored, both in academia and industry, as a possible alternative to dimensional scaling. This thesis focuses on how strain affects Si BJT and SiGe HBTs, where tensile strain is applied after the Integrated Circuit (IC) fabrication has been completed, using a unique mechanical method. The consequence of both biaxial and uniaxial strain application has been examined in this work. Chapter I gives a short introduction to the scope of this work, the motivation for conducting this research and the contributions of this experiment. Chapter II entails a brief discussion on Si bipolar and SiGe heterojunction bipolar device physics, which are key to the understanding of strain induced effects. Chapter III provides a thorough summary of the current state of research regarding applied strain, also known as Strain Engineering. It covers different types, orientations, and application techniques of strain. Chapter IV, highlights the details of this experiment, and also presents the measured results. It is observed that for this particular method of biaxial tensile strain application, the collector current (IC) and current gain degrades for both Si BJT and SiGe HBT. Base current (IB) decreases in Si BJT, though it increases for SiGe HBT after strain. Little or no change is noticed in the dynamic or ac small-signal characteristics like unity-gain cutoff frequency (fT) and base resistance (rBB) after strain. Uniaxially strained SiGe HBT samples showed similar results as the biaxial strain. This chapter also attempts to explain the origin of these strain induced changes. Chapter V, summarizes the finding of this experiment, and concludes the thesis with some future directions for this research.

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