Engineering Commons^™

Modeling And Characterization Of P-Type Silicon Carbide Gate Turn Off Thyristors, Osama Shihadeh Saadeh

Graduate Theses and Dissertations

Silicon carbide (SiC) power semiconductor devices have emerged in the past decade as the most promising technology for next generation power electronic applications ranging for electric vehicles to grid-connected power routing and conversion interfaces. Several devices have been developed, and even some have been released commercially, including diodes, MOSFETs, JFETs, thyristors, gate turn-off thyristors, and IGBTs. The model development, characterization and experimental validation of SiC p-type Gate Turn-off Thyristors (GTO) is presented in this work. The GTO device in this work is being used as part of a SiC-based solid-state fault current limiter under development at the University of Arkansas' …

Development Of Spray Cooling For High Heat Flux Electronics, Jeremy Scott Junghans

Graduate Theses and Dissertations

The thermal demands of modern day electronic systems require innovative thermal solutions. Spray cooling has proven to be able to cool heat fluxes orders of magnitude higher than traditional cooling methodologies. This work includes a comparison of spray cooling to standard thermal management methodologies. Key system parameters and considerations are discussed. The properties of available packaging materials and their effect on the reliability of a spray cooled system are presented. Parameters such as fluid temperature, droplet size, fluid velocity and flow rate all directly impact performance and are detailed in this work. Finally, results from of a wide range of …

Modeling Of Sic P-Channel Insulated Gate Bipolar Transistors (Igbts), Mahmood Saadeh

Graduate Theses and Dissertations

A new physics-based IGBT compact model has been developed for circuit simulation of silicon (Si) or silicon carbide (SiC) devices. The model accurately predicts the steady-state output, transfer and switching characteristics of the IGBT under a variety of different conditions. This is the first IGBT model to predict the behavior of p-channel SiC IGBTs. Previous work on IGBT models has focused on Si n-channel IGBTs [1-3]. This unified model is not limited to SiC p-channel IGBTs; the user has the option to select between Si or SiC, and n-channel or p-channel, making it the first IGBT model that captures the …

Photodetectors And Photovoltaic Devices Based On Semiconductor Nanomaterials, Jiang Wu

Graduate Theses and Dissertations

Photodetectors based various nanostructures and plasmon enhanced solar cells are investigated in this dissertation. The motivation of the dissertation rise is driven by urgent need of both high efficiency photodetectors and solar cells.

First, quantum dot infrared photodetectors have been intensely investigated due to their promise in high performance photodetectors. However, the strain-driven growth of quantum dots has hindered the progress of quantum dot photodetectors. The presence of strain in the device presents complexity in designing as well as defects. Therefore, in this project, new designs of quantum dot photodetector structures are presented to improve the control over detection wavelength. …

Investigation Of A Floating Load Buck Dc-Dc Switching Converter, Hong Tan

Graduate Theses and Dissertations

A floating load buck DC-DC switching converter was analyzed, simulated, designed and prototyped. The floating load buck converter is first compared to the conventional buck converter. It was found that both the floating load buck converter and conventional buck converter exhibit similar conversion characteristics despite the differences in the placement of their output inductors. A floating load buck converter was designed to be used as a high-voltage off-line light-emitting diodes (LEDs) driver using a Texas Instruments' TPS92001 controller. Finally, the characteristics of this floating load buck converter LED driver were experimentally examined.

Design Of A Low Noise Amplifier For Wireless Sensor Networks, Ting Liu

Graduate Theses and Dissertations

CMOS technology becomes important in Radio Frequency (RF) communication systems which include both a receiver and a transmitter. In a high performance radio receiver, the Low Noise Amplifier (LNA) is the first circuit, and its noise performance dominates the entire receiver. Depending upon the system in which they are used, LNAs can be designed according to various topologies and structures. The LNA needs to have matched input impedance, and at the same time it should amplify the small amplitude input signal without adding too much noise and still have the minimal power consumption. It also needs a good interface with …

Design Of An 866 Mhz On-Chip Frequency Synthesizer, Phaniraj Joshi

Graduate Theses and Dissertations

There is a strong need for stable frequency references with large tuning ranges in today's communication systems. While the crystal oscillators assure good frequency stability, it is not possible to achieve a large frequency range by tuning the passive components attached to them. Frequency synthesizers are usually used for this purpose because of their ability to produce a variety of output frequencies. The Phase Locked Loop (PLL) based frequency synthesizer is the most preferred of all types of synthesizers available because of its additional features like programmability, low noise and low cost as well as high accuracy and stability. The …

Fabrication Of Composite Nanomaterials For Thin Film Amorphous Silicon Solar Cells, Benjamin Seth Newton

Graduate Theses and Dissertations

A material with the precise combination of amorphous silicon and polycrystalline silicon would be able to take advantage of the high absorption capabilities of amorphous silicon and the electron transport capabilities of polycrystalline silicon. Polycrystalline nanostructures in the form of wires can also take advantage of other properties of light absorption, trapping and scattering inherent in nanowire structures. These properties of high absorption and electron transport in one device would lead to advances in the search for highly efficient low cost solar cells and sensors. In this work a thin film material composed of an array of polycrystalline silicon nanostructures …

Fabrication Of Horizontal Silicon Nanowires Using A Thin Aluminum Film As A Catalyst, Khaja Hafeezuddin Mohammed

Graduate Theses and Dissertations

Silicon nanowires have been the topic of research in recent years for their significant attention from the electronics industry to grow even smaller electronic devices. The semiconductor industry is built on silicon. Silicon nanowires can be the building blocks for future nanoelectronic devices. Various techniques have also been reported in fabricating the silicon nanowires. But most of the techniques reported, grow vertical silicon nanowires. In the semiconductor industry, integrated circuits are designed and fabricated in a horizontal architecture i.e. the device layout is flat compared to the substrate. When vertical silicon nanowires are introduced in the semiconductor industry, a whole …

File System Simulation: Hierarchical Performance Measurement And Modeling, Hai Quang Nguyen

Graduate Theses and Dissertations

File systems are very important components in a computer system. File system simulation can help to predict the performance of new system designs. It offers the advantages of the flexibility of modeling and the cost and time savings of utilizing simulation instead of full implementation. Being able to predict end-to-end file system performance against a pre-defined workload can help system designers to make decisions that could affect their entire product line, involving several million dollars of investment. This dissertation presents detailed simulation-based performance models of the Linux ext3 file system and the PVFS parallel file system. The models are developed …