Electronic Devices and Semiconductor Manufacturing Commons^™

Mass Reduction Patterning Of Silicon-On-Oxide-Based Micromirrors, Harris J. Hall, Andrew Green, Sarah Dooley, Jason D. Schmidt, Laverne A. Starman, Derrick Langley, Ronald A. Coutu Jr.

Faculty Publications

It has long been recognized in the design of micromirror-based optical systems that balancing static flatness of the mirror surface through structural design with the system’s mechanical dynamic response is challenging. Although a variety of mass reduction approaches have been presented in the literature to address this performance trade, there has been little quantifiable comparison reported. In this work, different mass reduction approaches, some unique to the work, are quantifiably compared with solid plate thinning in both curvature and mass using commercial finite element simulation of a specific square silicon-on-insulator–based micromirror geometry. Other important considerations for micromirror surfaces, including surface …

Improvements To Micro-Contact Performance And Reliability, Tod V. Laurvick

Theses and Dissertations

Microelectromechanical Systems (MEMS) based devices, and specifically microswitches, continue to offer many advantages over competing technologies. To realize the benefits of micro-switches, improvements must be made to address performance and reliability shortfalls which have long been an issue with this application. To improve the performance of these devices, the micro-contacts used in this technology must be understood to allow for design improvements, and offer a means for testing to validate this technology and determine when such improvements are ready for operational environments. To build devices which are more robust and capable of continued operation after billions of cycles requires that …

Investigation Of The Optical Properties Of Pbse/Pbx Nanocrystals For Photodetector Applications, Haley Ann Morris

Graduate Theses and Dissertations

Lead selenide and lead selenide/lead sulfide core/shell nanocrystals were investigated for use in near infrared photodetectors. A colloidal synthesis method was used for both the core and core/shell configurations. The lead sulfide shell was examined in order to mitigate oxidation of the nanoparticle surface. Absorbance and photoluminescence spectra were measured at room temperature and 77 K, respectively. Transmission electron microscopy images were also obtained to confirm crystallography and size. Bulk lead selenide was simulated in WIEN2k utilizing the linear-augmented plane wave method of solving density functional theory to better understand the electronic structure of PbSe. The crystal structure, electron density, …

Si-Based Germanium-Tin (Gesn) Emitters For Short-Wave Infrared Optoelectronics, Seyed Amir Ghetmiri

Graduate Theses and Dissertations

Conventional integrated electronics have reached a physical limit, and their efficiency has been influenced by the generated heat in the high-density electronic packages. Integrated photonic circuits based on the highly developed Si complementary-metal-oxide-semiconductor (CMOS) infrastructure was proposed as a viable solution; however, Si-based emitters are the most challenging component for the monolithic integrated photonic circuits. The indirect bandgap of silicon and germanium is a bottleneck for the further development of photonic and optoelectronic integrated circuits.

The Ge1-xSnx alloy, a group IV material system compatible with Si CMOS technology, was suggested as a desirable material that theoretically exhibits a direct bandgap …

Design, Fabrication And Measurement Of A Plasmonic Enhanced Terahertz Photoconductive Antenna, Nathan Matthias Burford

Graduate Theses and Dissertations

Generation of broadband terahertz (THz) pulses from ultrafast photoconductive antennas (PCAs) is an attractive method for THz spectroscopy and imaging. This provides a wide frequency bandwidth (0.1-4 THz) as well as the straightforward recovery of both the magnitude and phase of the transmitted and/or reflected signals. The achieved output THz power is low, approximately a few microwatts. This is due to the poor conversion of the femtosecond laser used as the optical pump to useable current inside the antenna semiconducting material. The majority of THz power comes from the photocarriers generated within ~ 100 nm distance from the antenna electrodes. …

Growth Of Gesn And Gepb Alloy Films Using Thermal Evaporator, Hakimah Alahmed

Graduate Theses and Dissertations

Silicon is the most important semiconductor material used in microelectronic devices. As the number of transistors keep doubling every 24 months (Moore’s law), transistors continue scaling down in size, electrical interconnect is reaching its limits to keep up with the scaling down rate in integrated circuits. These limitations are related to interconnect density and power consumption. Hence, replacing electrical interconnect with optical interconnect on the chip or between chips has the ability to overcome these limitations. However, silicon has poor light emitting efficiency, and other substitutes such as III-V materials are not suitable due to high cost, lattice mismatch, and …

Strategies And Techniques For Fabricating Mems Bistable Thermal Actuators., Dilan Ratnayake

Electronic Theses and Dissertations

Bistable elements are beginning to appear in the field of MEMS as they allow engineers to design sensors and actuators which require no electrical power and possess mechanical memory. This research focuses on the development of novel strategies and techniques for fabricating MEMS bistable structures to serve as no electrical power thermal actuators. Two parallel strategies were explored for the design and fabrication of the critical bistable element. Both strategies involved an extensive material study on candidate thin film materials to determine their temperature coefficient of expansion and as-deposited internal stress properties. Materials investigated included titanium tungsten, Invar, silicon nitride …

Measurement And Analysis Of Iii-V & Ii-Vi Infrared Detectors: Radiometric, Noise Spectrum, And Radiation Tolerance Performance, Vincent M. Cowan

Nanoscience and Microsystems ETDs

Infrared (IR) hybrid detector arrays and discrete detectors operated in the space environment may be subjected to a variety of sources of natural radiation while in orbit. This means IR detectors intended for applications such as space-based intelligence, surveillance, and reconnaissance (ISR) or space-situational awareness (SSA) must not only have high performance (high quantum efficiency, h and low dark-current density, J_D, and preferably minimal 1/f noise content), but also their radiation tolerance or ability to withstand the effects of the radiation they would expect to encounter in space must be characterized and well understood. As the effects of …

"Feasibility Of Efficient Photovoltaics In Eastern Kentucky" / "Developing A 3-D Printed Solar Vehicle With Computational Fluid Dynamics (Cfd) Simulator", Adam N. Stanley, Matthew R. Hezseltine

Posters-at-the-Capitol

Abstract 1

Feasibility of Efficient Photovoltaics in Eastern Kentucky

Photovoltaics (PV-also called solar photovoltaic devices) are used to harness the power of the sun via the electronic process that occurs within semiconductor cells. The solar energy is absorbed by the cells, which causes the electrons to break away from their atoms, allowing them to flow within the material to produce electricity. This electricity will become the renewable energy for Kentucky, as the generation of coal will but come to a stop within the near future. Like Denmark who is running on 100% renewable generation we must stride to become fully …

High Power Optically Pumped Semiconductor Lasers For Sodium Guidestar Applications, Shawn W. Hackett

Optical Science and Engineering ETDs

Optically pumped semiconductor lasers (OPSLs) are shown to provide a much more compact and less expensive source for illumination of the sodium layer of the mesosphere for use as a sodium laser guidestar via single and two photon excitation schemes. This represents a revolution in laser guidestar technology as the cost, size, and power requirements for a laser guidestar system are shown to have been decreased by an order of magnitude with guidestar performance shown to be similar to previous sources. Sodium laser guidestar sources for broadband simultaneous illumination of multiple lines are developed and simulated. Simulations are then compared …

Pattern Reconfigurable Back-To-Back Microstrip Patch Antenna, Kansheng Yang, Xiulong Bao, Patrick Mcevoy, Max Ammann

Articles

A back-to- back microstrip patch antenna with a switchable pattern is proposed for WLAN applications. The patch elements, printed on FR-4 substrates with a common ground plane, are switched with a single-pole double-throw PIN diode circuit. Switching the feed selects either of two identical radiation patterns in the opposing hemispheres for spatial diversity that would benefit a distributed network.

Inquiry Of Graphene Electronic Fabrication, John Rausch Greene

Master's Theses

Graphene electronics represent a developing field where many material properties and devices characteristics are still unknown. Researching several possible fabrication processes creates a fabrication process using resources found at Cal Poly a local industry sponsor. The project attempts to produce a graphene network in the shape of a fractal Sierpinski carpet. The fractal geometry proves that PDMS microfluidic channels produce the fine feature dimensions desired during graphene oxide deposit. Thermal reduction then reduces the graphene oxide into a purified state of graphene. Issues arise during thermal reduction because of excessive oxygen content in the furnace. The excess oxygen results in …

Thermal Management Using Mems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. Walton, Laverne A. Starman

Faculty Publications

This paper examines a passive cooling technique using microelectromechanical systems (MEMS) for localized thermal management of electronic devices. The prototype was designed using analytic equations, simulated using finite element methods (FEM), and fabricated using the commercial PolyMUMPs™ process. The system consisted of an electronic device simulator (EDS) and MEMS bimorph cantilever beams (MBCB) array with beams lengths of 200, 250, and 300 μm that were tested to characterize deflection and thermal behavior. The specific beam lengths were chosen to actuate in response to heating associated with the EDS (i.e. the longest beams actuated first corresponding to the hottest portion of …

Direct Bandgap Cross-Over Point Of Ge1-YSnY Grown On Si Estimated Through Temperature-Dependent Photoluminescence Studies, Thomas R. Harris, Mee-Yi Ryu, Yung Kee Yeo, Buguo Wang, C. L. Senaratne

Faculty Publications

Epitaxial Ge_1-ySn_y (y = 0%–7.5%) alloys grown on either Si or Ge-buffered Si substrates by chemical vapor deposition were studied as a function of Sn content using temperature-dependent photoluminescence (PL). PL emission peaks from both the direct bandgap (Γ-valley) and the indirect bandgap (L-valley) to the valence band (denoted by E_D and EID, respectively) were clearly observed at 125 and 175 K for most Ge_1-ySn_y samples studied. At 300 K, however, all of the samples exhibited dominant E_D emission with either very weak or no measureable E_ID emission. At 10 K, …

Atomistic Configuration Interaction Simulation Tool For Semiconductor Based Quantum Computing Devices, Jingbo Wu, Archana Tankasala, Jim Fonseca, Rajib Rahman, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

Solid-state devices are promising candidates for quantum computing applications due to obvious advantages in compatibility with semiconductor fabrication technologies and the extremely long coherent times of electron and nuclear spins in these devices. In such devices, electron interactions are crucial for single and two qubit gate operations. Thus it is essential to evaluate these electron-electron interactions accurately for precise qubit control. It is shown that Atomistic Configuration Interaction can be used to accurately determine electron-electron interactions in realistic semiconductor quantum computing devices. In this work, an online simulation tool on Atomistic Configuration Interaction has been implemented and published on nanoHUB.org, …

Large Scale Monolithic Solar Panel Simulation - A Study On Partial Shading Degradation, Suhas V. Baddela, Xingshu Sun, Muhammad A. Alam

The Summer Undergraduate Research Fellowship (SURF) Symposium

Shadow-induced degradation is a major concern for both power output and long-term reliability in solar cells. Apart from the obvious fact that shading reduces the amount of solar irradiance available to solar panels, it may lead to formation of hot spots, where solar cells are forced to reverse breakdown with localized heating, and potentially, permanent damage. To get a better understanding of shadow-induced degradation, we develop an electro-thermal coupled simulator that can self-consistently solve the electrical and thermal distributions of solar panel under arbitrary shading conditions. The simulation framework consists of two part: a) compact models that can describe the …

Compact Modeling Of Sic Insulated Gate Bipolar Transistors, Sonia Perez

Graduate Theses and Dissertations

This thesis presents a unified (n-channel and p-channel) silicon/silicon carbide Insulated Gate Bipolar Transistor (IGBT) compact model in both MAST and Verilog-A formats. Initially, the existing MAST model mobility equations were updated using recently referenced silicon carbide (SiC) data. The updated MAST model was then verified for each device tested. Specifically, the updated MAST model was verified for the following IGBT devices and operation temperatures: n-channel silicon at 25 ˚C and at 125 ˚C; n-channel SiC at 25 ˚C and at 175 ˚C; and p-channel SiC at 150 ˚C and at 250 ˚C. Verification was performed through capacitance, DC output …

Modeling And Simulation Of 1700 V 8 A Genesic Superjunction Transistor, Staci E. Brooks

Graduate Theses and Dissertations

The first-ever 1.7kV 8A SiC physics-based compact SPICE model is developed for behavior prediction, modeling and simulation of the GeneSiC “Super” Junction Transistor. The model implements Gummel-Poon based equations and adds a quasi-saturation collector series resistance representation from a 1.2 kV, 6 A SiC bipolar junction transistor model developed in Hangzhou, China. The model has been validated with the GA08JT17-247 device data representing both static and dynamic characteristics from GeneSiC. Parameter extraction was performed in IC-CAP and results include plots showing output characteristics, capacitance versus voltage (C-V), and switching characteristics for 25 °C, 125 °C, and 175 °C temperatures.

Active Charge Balancing For Cardiac Stimulation, Maci Miri

Electrical Engineering

Worldwide, there are about 3 million people who have pacemakers, with 10,000 new implantations of ICD’s each month. [heart.org] Due to the gravity and importance of the function that ICD’s provide, these devices must be extremely reliable and highly effective. However, because of the high tolerances of IC manufacturing, stimulation circuits for pacemakers may be slightly unmatched and over time, may have a net DC charge applied to the tissues in the heart. Extra charge pumped into body tissues is dangerous for the patient’s health; the pH of the tissue can be raised and corrosion of the stimulating electrodes may …

Smart Gate Driver Design For Silicon (Si) Igbts And Silicon-Carbide (Sic) Mosfets, Abdulaziz Alghanem

Electrical Engineering Undergraduate Honors Theses

The design of an efficient and smart gate driver for a Si IGBT and SiC MOSFET is addressed in thesis. First, the main IGBT parameters are evaluated thoroughly in order to understand their effects in the design of the gate driver. All known consequences of previously designed gate drivers are studied in order to achieve an optimum gate driver. As a result of this assessment, the designer is able to determine whether adding or removing components from the gate driver circuit are beneficial or not. Then, exhaustive research is done to identify suitable integrated circuits to use for the power …

Numerical And Analytical Modeling To Determine Performance Trade-Offs In Hydrogel-Based Ph Sensors, Piyush Dak, Muhammad Ashraful Alam

Birck and NCN Publications

Hydrogel based pH sensors are promising candidates for implantable sensors due to their low-cost and biocompatibility. Despite their commercial potential and numerous theoretical/experimental reports, the trade-offs between different performance parameters are not well understood, and explicitly stated. In this work, we develop a numerical and analytical framework to show that there is a fundamental trade-off between the performance parameters i.e. sensitivity/dynamic range vs. response-time/response-asymmetry in hydrogel sensors under constrained swelling conditions. Specifically, we consider the effect of the gel parameters, such as the ionizable group density ( N_f) and its dissociation constant ( K_a), on the …

Growth, Characterization And Simulation Of Tungsten Selenide Thin Films For Photovoltaic Applications, Qinglei Ma

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

An excellent candidate for an earth abundant absorber material is tungsten selenide (WSe₂) which can be directly grown as a p-type semiconductor with a band gap value that matches well the solar spectrum. Although several fabrication methods were reported, further improvement is highly needed to make high quality WSe₂ films. In addition, the numerical modelling of WSe₂ solar devices is highly desired to assess the overall utility of the material. In this work, the growth and characterization of tungsten selenide thin films are investigated, as well simulations of homo- and hetero-junction devices. In the first part, …

Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell

Electronic Theses and Dissertations

Photoelectrochemical water splitting has been identified as a promising route for achieving sustainable energy future. However, semiconductor materials with the appropriate optical, electrical and electrochemical properties have yet to be discovered. In search of an appropriate semiconductor to fill this gap, GaSbP, a semiconductor never tested for PEC performance is proposed here and investigated. Density functional theory (DFT+U) techniques were utilized to predict band gap and band edge energetics for GaSbP alloys with low amount of antimony. The overall objective of this dissertation is to understand the suitability of GaSb_xP_1-x alloys for photoelectrochemical water splitting application. Specifically, …

Characterization For The Development Of The Hybrid Multi-Junction Silicon Germanium Solar Cell, Jimmy J. Lohrman

Theses and Dissertations

Based on the previous development of the hybrid multi-junction silicon (HMJ-Si) solar cell, this work characterized the preceding design for the development of the hybrid multi-junction silicon germanium (HMJ-SiGe) solar cell. Seven focus areas were investigated: diffraction pattern generation, photon propagation, silicon diffusion processing, ohmic contacts, the distributed Bragg reflector (DBR), the Fresnel zone plate (FZP), and the germanium/germanium telluride (Ge/GeTe) pn-junction Diffraction patterns were theoretically examined, and contact grating design characterization for reflectance and transmittance properties was modeled using rigorous coupled wave analysis. An improved silicon diffusion process follower was developed, and theoretical study and experimental assessment were accomplished …

Optically Stimulated Luminescence From Ag-Doped Lithium Tetraborate (Li2b4o7), Ember S. Maniego

Theses and Dissertations

Silver-doped lithium tetraborate (Li₂B₄O₇) crystals emit optically stimulated luminescence (OSL) in response to stimulating light around 400 nm. Photoluminescence, optical absorption, and electron paramagnetic resonance (EPR) were used to identify the defects in the crystal that cause this OSL. Lithium tetraborate crystals have Ag⁺ ions at Li⁺ sites and at interstitial sites. Upon ionization at room temperature via x rays, electron-hole pairs are generated. The electrons are trapped at Ag⁺ occupying interstitial sites, while the holes are trapped at Ag⁺ at lithium sites. The trapped electron centers become Ag^{0 …}

Neutron Radiation Effects On Ge And Gesn Semiconductors, Christopher T. O'Daniel

Theses and Dissertations

Two different semiconductor materials received neutron radiation for assessment of radiation damage. The two materials are undoped bulk Ge and epitaxial Ge_0.991Sn_0.009, which is doped heavily with phosphorous. At room temperature, the Ge sample has direct and indirect bandgaps at 0.78 eV and 0.66 eV, respectively. The Ge_0.991Sn_0.009 sample has direct and indirect bandgaps at 0.72 eV and 0.63 eV, respectively. Two samples of each material were exposed to research reactor neutrons, delivering a 1 MeV equivalent neutron fluence of 2.52 × 10¹⁵ n/cm². In order to assess the radiation …

Amorphous Silicon Solar Vivaldi Antenna, Oisin O'Conchubhair, Kansheng Yang, Patrick Mcevoy, Max Ammann

Articles

An ultra-wideband solar Vivaldi antenna is proposed. Cut from amorphous silicon cells, it maintains a peak power at 4.25 V which overcomes a need for lossy power management components. The wireless communications device can yield solar energy or function as a rectenna for dual-source energy harvesting. The solar Vivaldi performs with 0.5 - 2.8 dBi gain from 0.95 - 2.45 GHz and in rectenna mode, it covers three bands for wireless energy scavenging.

Out-Of-Loop Compensation Method For Op-Amps Driving Heavy Capacitive Loads, Shubham Gandhi

Master's Theses

It is well known that real op-amps do not share most of the desirable characteristics of an ideal one, particularly those of gain and output impedance. When presented with a capacitive load, such as a MOSFET or ADC, feedback in an op-amp circuit can quickly become unstable. This thesis studies and characterizes an op-amp’s output impedance and how its interaction with this type of load creates a parasitic pole which leads to instability. Applying ideas from feedback control theory, a model for studying the problem is developed from which a generalized method for compensating the undesirable circumstance is formulated.

Even …

Electron Beam Induced Deposition Of Highly Conductive Copper Nanowires From Bulk Liquids, Amjad M. Syam

Theses and Dissertations--Electrical and Computer Engineering

Electron-beam induced deposition (EBID) is a position-controlled technique that can directly fabricate nanometer-sized structures in functional materials. In the standard process, a gaseous precursor delivers the desired substance to the substrate for deposition. However, the material purity from these precursors is typically poor, which often negatively affects the functional properties of the deposit. Recently, bulk liquid precursors have been investigated as promising reactants for high purity deposition without the need for post-processing. In this work, EBID from bulk liquids is shown to yield highly conductive nanowire deposits. Aqueous solutions containing copper sulfate (CuSO₄) and sulfuric acid (H_{2 …}

Ultra–Low Power Straintronic Nanomagnetic Computing With Saw Waves: An Experimental Study Of Saw Induced Magnetization Switching And Properties Of Magnetic Nanostructures, Vimal G. Sampath

Theses and Dissertations

A recent International Technology Roadmap for Semiconductors (ITRS) report (2.0, 2015 edition) has shown that Moore’s law is unlikely to hold beyond 2028. There is a need for alternate devices to replace CMOS based devices, if further miniaturization and high energy efficiency is desired. The goal of this dissertation is to experimentally demonstrate the feasibility of nanomagnetic memory and logic devices that can be clocked with acoustic waves in an extremely energy efficient manner. While clocking nanomagnetic logic by stressing the magnetostrictive layer of a multiferroic logic element with with an electric field applied across the piezoelectric layer is known …