Electronic Devices and Semiconductor Manufacturing Commons^™

Automation Programming For Uhv-Cvd Growth Of Group Iv Materials, William Hay

Electrical Engineering and Computer Science Undergraduate Honors Theses

The automation programming of a UHV-CVD reactor for group IV materials was performed. The reactor was programmed to perform all the necessary functions for a Germanium (Ge) growth with little response from the user. The overall goal was to fix an Argon purge program to clean out the process chamber of gases and create an Excel output program to ease any work on the user. There were also general fixes and address name changes that occurred throughout the program. Then, a one step and two step growth of a Ge material was formed in a UHV-CVD reaction for analysis. Germanium …

Defect Characterization Of Sic Schottky Barrier Diode Using Deep Level Transient Spectroscopy, Zachary I. Mccoy

Electrical Engineering and Computer Science Undergraduate Honors Theses

The aim of this project is to use deep level transient spectroscopy (DLTS) to energetically evaluate defects by using the carrier concentration dependence on temperature and where these carriers may experience deviation from standard predictions. These defects become apparent through multiple C-V measurements that are swept through a temperature range. By analyzing trends with respect to temperature, the defects can be energetically “located,” and thus identified. This identification can help streamline semiconductor material manufacturing/growth because DLTS identifies potential defect causes by providing data to characterize semiconductor mid-band defects. DLTS can assess nearly all parameters associated with traps/defects including density, thermal …

Investigation And Characterization Of Silicon Carbide Power Mosfets, Vincent Hassman

Electrical Engineering and Computer Science Undergraduate Honors Theses

As engineers constantly seek to make solar power systems smaller, cheaper, and more efficient, technological enhancements in the electronics that run them are required. One of the most fundamental electronic components of any solar system is the inverter, which takes DC current from the solar cell and turns it into AC current that is supported by the grid. This is done with metal oxide semiconductor field effect transistors (MOSFETs). Through more advanced MOSFET technology, inverters can switch at a higher frequency, increasing efficiency and reducing size and cost.

MOSFET performance can be enhanced by swapping the traditional silicon substrate with …

Characterization Of Highly Doped N-Type And P-Type Silicon Carbide Ohmic Contacts, Tanner Rice

Graduate Theses and Dissertations

Silicon Carbide (SiC) is a rather new material that possesses unparalleled properties when compared to Silicon. Due to its larger band gap alongside other thermal properties, SiC can survive in hotter, more radiation intensive environments, whether that be within the crust of the earth or in the reaches of space. As a desirable semiconductor for these applications, CMOS is an especially important device due to its low power consumption. However, creating a good contact between the metal and semiconductor optimally requires two different metals for the n -type and the p-type semiconductor. This greatly increases the processing time, as separate …

Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers

Physics Undergraduate Honors Theses

Terahertz (THz) photoconductive antennas (PCAs) using 40nm thin-film flakes of black phosphorus (BP) and hexagonal boron nitride (hBN) have been shown computationally to be capable of THz emission comparable to those based on GaAs [2]. In this paper, I briefly describe the scientific and practical interest in THz emissions and explain what warrants research into black phosphorus as a photoconductive semiconductor in THz devices. Furthermore, I outline the basic principle of how these antennas work and mention alternative designs produced by other researchers in the past. Finally, I summarize the fabrication process of these antennas, as well as the measurements …

The Wideband Tunability Of Double Gunn Diodes, Latarence Butts, Samir M. El-Ghazaly

Electrical Engineering Faculty Publications and Presentations

Gunn diodes use the Ridley–Watkins–Hilsum effect to generate low noise millimeter wave signals for communication and sensing applications. However, Monte Carlo calculations indicate that the velocity–field characteristics of compensated GaAs contain a second peak due to phonon scattering. A novel device that leverages this double Ridley–Watkins–Hilsum effect to achieve ultra-wideband tunability of low-noise millimeter waves is proposed in this article. The second region of negative differential mobility is gradually introduced in seven mobility profiles, which are each simulated in eight device lengths. It is found that a 2.5 μm Gunn diode with a compensation ratio of 0.6 operating at …

Experimental And Computational Analysis Of Broadband Thz Photoconductive Antennas, Zachary Uttley, Jose Santos Batista, Bilal Pirzada, Magda El-Shenawee

Electrical Engineering Faculty Publications and Presentations

The work presents the fabrication and measurements of four LT-GaAs photoconductive terahertz (THz) antennas with different geometries of metallic electrodes. The goal is to analyze the overall bandwidth of the antennas through a comparison between the spectra of the generated photocurrent in the antenna gap, the radiated electric field THz pulse, and the S₁₁ parameter of the metallic electrodes. The photocurrent density and the S₁₁ parameters are computed using COMSOL multiphysics, while the generated THz pulse was experimentally measured using a time-domain spectroscopy system. The polarizations of the photoconductive antennas are experimentally measured, using x-cut quartz crystal halfwave …

Gate-Controlled Quantum Dots In Two-Dimensional Tungsten Diselenide And One-Dimensional Tellurium Nanowires, Shiva Davari Dolatabadi

Graduate Theses and Dissertations

This work focuses on the investigation of gate-defined quantum dots in two-dimensional transition metal dichalcogenide tungsten diselenide (WSe2) as a means to unravel mesoscopic physical phenomena such as valley-contrasting physics in WSe2 flakes and its potential application as qubit, as well as realizing gate-controlled quantum dots based on elementaltellurium nanostructures which may unlock the topological nature of the host material carriers such as Weyl states in tellurium nanowires.The fabrication and characterization of gate-defined hole quantum dots in monolayer and bilayer WSe2 are reported. The gate electrodes in the device design are located above and below the WSe2 nanoflakes to accumulate …

Reliability Enhancing Control Algorithms For Two-Stage Grid-Tied Inverters, Yuheng Wu

Graduate Theses and Dissertations

In the photovoltaic (PV) generation system, two types of grid-tied inverter systems are usually deployed: the single-stage grid-tied inverter system and the two-stage grid-tied inverter system. In the single-stage grid-tied inverter system, the input of the inverter is directly connected to the PV arrays, while an additional dc-dc stage is inserted between the PV arrays and the dc-ac inverter in the two-stage design. The additional dc-dc stage could provide a stable dc-link voltage to the inverter, which also enables new design possibilities, including the multi-MPPT operation and solar-plus-storage application. Thus, the two-stage grid-tied inverter has been widely used in the …

Improved Compact Modeling Of High Voltage Gallium Nitride High Electron Mobility Transistors, Md Maksudul Hossain

Graduate Theses and Dissertations

Since power converters shape a wide range of power electronic applications, the 'heart' of these conversions, such as solid-state switches, is crucial for achieving higher power density, lower loss, and higher efficiency operations. Although the limitations imposed by silicon-based power devices have been reduced by introducing novel devices such as IGBTs and super junction MOSFETs to allow for broader applications, solutions beyond silicon have presented a continuous challenge to the device engineers. Driving these converters at a higher switching frequency allows for higher power density. However, to support a higher frequency and operating temperature, superior materials, e.g., wide bandgap materials, …

Hybrid Multilevel Converters With Internal Cascaded/Paralleled Structures For Mv Electric Aircraft Applications, Fei Diao

Graduate Theses and Dissertations

Using on-board medium voltage (MV) dc distribution system has been a megatrend for next-generation electric aircraft systems due to its ability to enable a significant system mass reduction. In addition, it makes electric propulsion more feasible using MV power electronic converters. To develop high-performance high-density MV power converters, the emerging silicon carbide (SiC) devices are more attractive than their silicon (Si) counterparts, since the fast switch frequency brought by the SiC can effectively reduce the volume and weight of the filter components and thus increase the converter power density. From the converter topology perspective, with the MV dc distribution, the …

Etching Process Development For Sic Cmos, Weston Reed Renfrow

Graduate Theses and Dissertations

Silicon Carbide (SiC) is an exciting material that is growing in popularity for having qualities that make it a helpful semiconductor in extreme environments where silicon devices fail. The development of a SiC CMOS is in its infancy. There are many improvements that need to be made to develop this technology further. Photolithography is the most significant bottleneck in the etching process; it was studied and improved upon. Etching SiC can be a challenge with its reinforced crystal structure. Chlorine-based inductively coupled plasma (ICP) etching of intrinsic SiC and doped SiC, SiO2, and Silicon has been studied. A baseline chlorine …

Study Of Thin Gan/Ingan/Gan Double Graded Structures For Future Photovoltaic Application, Mirsaeid Sarollahi

Graduate Theses and Dissertations

Indium gallium nitride (In_x Ga_(1-x) N) materials have displayed great potential for photovoltaic and optoelectronic devices due to their optical and electrical properties. Properties such as direct bandgap, strong bandgap absorption, thermal stability and high radiation resistance qualify them as great materials for photovoltaic devices. The tunable bandgap which absorbs the whole solar spectrum is the most significant feature which became attractive for scientists. The bandgap for these materials varies from 0.7 eV for InN to 3.4 eV for GaN covering from infrared to ultraviolet. In_x Ga_(1-x) N wurtzite crystal is grown on GaN buffer layer by Molecular Beam Epitaxy …

Design Of A Bandgap Voltage Reference, Nicolaus Vail

Electrical Engineering Undergraduate Honors Theses

This thesis details the design process of a bandgap voltage reference (BGR) integrated circuit in a 180 nm CMOS process. A BGR provides a constant DC voltage across a range of operating temperatures and supply voltages. By its nature, the circuit is intended as a reference, not to provide current, so the output would be connected to a very high impedance, such as the gate of a transistor. At 27°C, this design provides a 955 mV reference voltage given a nominal VDD of 3 V. From 20°C to 175°C, the output voltage has a variance of 7.2 mV (approximately 0.8%) …

Investigation Of Optical And Structural Properties Of Gesn Heterostructures, Oluwatobi Gabriel Olorunsola

Graduate Theses and Dissertations

Silicon (Si)-based optoelectronics have gained traction due to its primed versatility at developing light-based technologies. Si, however, features indirect bandgap characteristics and suffers relegated optical properties compared to its III-V counterparts. III-Vs have also been hybridized to Si platforms but the resulting technologies are expensive and incompatible with standard complementary-metal-oxide-semiconductor processes. Germanium (Ge), on the other hand, have been engineered to behave like direct bandgap material through tensile strain interventions but are well short of attaining extensive wavelength coverage. To create a competitive material that evades these challenges, transitional amounts of Sn can be incorporated into Ge matrix to form …

A Double-Sided Stack Low-Inductance Wire-Bondless Sic Power Module With A Ceramic Interposer, Si Huang

Graduate Theses and Dissertations

The objective of this dissertation research is to develop a novel three-dimensional (3-D) wire bondless power module package for silicon carbide (SiC) power devices to achieve a low parasitic inductance and an improved thermal performance. A half-bridge module consisting of 900-V SiC MOSFETs is realized to minimize stray parasitic inductance as well as to provide both vertical and horizontal cooling paths to maximize heat dissipation. The proposed 3-D power module package was designed, simulated, fabricated and tested. In this module, low temperature co-fired ceramic (LTCC) substrate with vias is utilized as an interposer of which both top and bottom sides …

Distributed Modeling Approach For Electrical And Thermal Analysis Of High-Frequency Transistors, Amirreza Ghadimi Avval

Graduate Theses and Dissertations

The research conducted in this dissertation is focused on developing modeling approaches for analyzing high-frequency transistors and present solutions for optimizing the device output power and gain. First, a literature review of different transistor types utilized in high-frequency regions is conducted and gallium nitride high electron mobility transistor is identified as the promising device for these bands. Different structural configurations and operating modes of these transistors are explained, and their applications are discussed. Equivalent circuit models and physics-based models are also introduced and their limitations for analyzing the small-signal and large-signal behavior of these devices are explained. Next, a model …

Direct Torque Control For Silicon Carbide Motor Drives, Mohammad Hazzaz Mahmud

Graduate Theses and Dissertations

Direct torque control (DTC) is an extensively used control method for motor drives due to its unique advantages, e.g., the fast dynamic response and the robustness against motor parameters variations, uncertainties, and external disturbances. Using higher switching frequency is generally required by DTC to reduce the torque ripples and decrease stator current total harmonic distortion (THD), which however can lower the drive efficiency. Through the use of the emerging silicon carbide (SiC) devices, which have lower switching losses compared to their silicon counterparts, it is feasible to achieve high efficiency and low torque ripple simultaneously for DTC drives.

To overcome …

Use Of The Igbt Module In The Active Region To Design A High Current Active Filter, Jorge F. Galarraga

Graduate Theses and Dissertations

Particle accelerators require high-precision magnetic fields on the order or 100ppm or less. This implies that the precision of the associated electrical current in the electromagnet that generates these fields should be smaller than 100ppm. However, conventional switching power supplies cannot offer this precision due to the frequency limitation of the switches. This research considers the use of power electronics devices operating in a linear as an alternative solution to meet the requirements of particle accelerator electromagnets.

This thesis presents the study of an insulated-gate bipolar transistor (IGBT) driver using a new control method that linearizes the IGBT’s collector-emitter voltage …

Design And Validation Of A High-Power, High Density All Silicon Carbide Three-Level Inverter, Zhongjing Wang

Graduate Theses and Dissertations

Transportation electrification is clearly the road toward the future. Compared to internal combustion engine, the electrified vehicle has less carbon-dioxide emission, less maintenance costs and less operation costs. It also offers higher efficiency and safety margin. More importantly, it relieves human’s dependence on conventional fossil energy. In the electrification progress, the revolution of electric traction drive systems is one of the most important milestone. The traction system should keep high efficiency to avoid performance reduction. Moreover, the motor drive should be designed within limited space without sacrificing output power rating. Based on the road map from US Drive Electrical and …

Malicious Hardware & Its Effects On Industry, Gustavo Perez

Computer Science and Computer Engineering Undergraduate Honors Theses

In recent years advancements have been made in computer hardware security to circumnavigate the threat of malicious hardware. Threats come in several forms during the development and overall life cycle of computer hardware and I aim to highlight those key points. I will illustrate the various ways in which attackers exploit flaws in a chip design, or how malicious parties take advantage of the many steps required to design and fabricate hardware. Due to these exploits, the industry and consumers have suffered damages in the form of financial loss, physical harm, breaches of personal data, and a multitude of other …

Design And Fabrication Of A Microstrip Bandpass Filter In Ltcc, Allison Rucker

Electrical Engineering Undergraduate Honors Theses

The goal of the project was to design and fabricate a bandpass filter with a center frequency of 25GHz with a 2GHz bandwidth. The first step was to do the calculation to design a bandpass filter to meet these specifications along with the properties of the Dupont^TM GreenTape^TM 9K7. HFSS was then used to verify the results from the initial calculations. There was a significant error between the two results, so more tweaking was done to the calculations to get a better center frequency. After a final design was decided, the fabrication process started. Low-Temperature Co-Fired Ceramics (LLTC) …

Transimpedance Amplification Of Optocoupler Output For High Temperature Applications, Kara Maurer

Electrical Engineering Undergraduate Honors Theses

When looking to the future of electronics, one characteristic is becoming more lucrative: high temperature capabilities. With the goals of not only becoming more efficient electronically, spatially, and cost-wise, adapting electronics for a high temperature environment can potentially be a route to all three of these goals. Not only does it take away the need for a cooling method, but it can also increase the longevity of a product which can make it even more cost effective. In an effort to contribute to the push for high temperature electronics, the University of Arkansas is developing a high temperature power module …

Optoelectronic Valley-Spin Qubits With Ambipolar Quantum Dots, Jeremy Tull

Electrical Engineering Undergraduate Honors Theses

The current limitations of qubit-based processors are caused by imperfections in quantum gates, leading to a lack of gate fidelity. Gate fidelity can be refined by extending the coherence of qubits and reducing logic operation speed. A potential solution is to develop a hybrid qubit that has the coherence of electrically-controlled quantum dots and the gate speed of their optically-controlled counterparts. Quantum bits that utilize ultrafast optical gating to perform gate operations require precise control of the gating pulse duration. Optical dispersion can cause adverse effects pulse duration, such as pulse broadening, so dispersion-compensation techniques must be employed; by properly …

Effect Of Silicon Carbide On Electric Drivetrains Of Heavy-Duty Vehicles, Haley Solera

Electrical Engineering Undergraduate Honors Theses

The application of electro-mechanical motors in rigorous, high-temperature systems is constantly adapting to suit the growing needs of developers in the automotive, construction, and aerospace industries. With improved efficiency, torque, and environmental impact over conventional internal combustion engines, electric drive trains pose more than ample incentive for manufacturers to invest considerable resources toward the design of newer, better methods of electric propulsion. This paper discusses the motives behind the electrification of heavy-duty vehicles, the state-of-the-art technology currently available on the market, and the novel application of silicon carbide to electric drive trains as a means of increasing their heat tolerance, …

Si-Based Germanium Tin Photodetectors For Infrared Imaging And High-Speed Detection, Huong Tran

Graduate Theses and Dissertations

Infrared (IR) radiation spans the wavelengths of the windows: (1) near-IR region ranging from 0.8 to 1.0 μm, (2) shortwave IR (SWIR) ranging from 1.0 to 3.0 μm, (3) mid-wave IR (MWIR) region covering from 3.0 to 5.0 μm, (4) longwave IR (LWIR) spanning from 8.0 to 12.0 μm, and (5) very longwave IR extending beyond 12.0 μm. The MWIR and LWIR regions are important for night vision in the military, and since the atmosphere does not absorb at these wavelengths, they are also used for free-space communications and astronomy. Automotive and defect detection in the food industry and electronic …

Analysis Of Photodetector Based On Zinc Oxide And Cesium Lead Bromide Heterostructure With Interdigital Metallization, Tanveer Ahmed Siddique

Graduate Theses and Dissertations

In this thesis, photodetector based on the zinc oxide and cesium lead bromide hetero structure were fabricated and characterized. Zinc oxide (ZnO) nanoparticles were synthesized using solution processing and cesium lead bromide (CsPbBr3) thin film was synthesized using two step deposition method. Three phonon modes were obtained by the Raman spectroscopy of ZnO nanoparticles. X-ray diffraction spectra of ZnO exhibits five exciton peaks which denotes that the synthesized ZnO structure was of good crystallinity with wurtzite hexagonal phase. The absorbance spectrum of ZnO shows the bandgap (Eg) in the order of 3.5 eV that aligns with reported results. The photoluminescence …

An Accurate And Efficient Electro-Thermal Compact Model Of Sic Power Mosfet Including Third Quadrant Behavior, Arman Ur Rashid

Graduate Theses and Dissertations

Due to narrower bandgap and lower critical electric field, silicon (Si) power devices have reached their limit in terms of the maximum blocking voltage capability. Exploiting this limitation, wide bandgap devices, namely silicon carbide (SiC) and gallium nitride (GaN) devices, are increasingly encroaching on the lucrative power electronics market. Unlike GaN, SiC devices can exploit most of the established fabrication techniques of Si power devices. Having substrate of the same material, vertical device structures with higher breakdown capabilities are feasible in SiC, unlike their GaN counterpart. Also, the excellent thermal conductivity of SiC, compared to GaN and Si, let SiC …

Performance And Economics Of Solar Inverters And Module Level Power Electronics In A 1 Mw Photovoltaic System, Maxwell Criswell

Biological and Agricultural Engineering Undergraduate Honors Theses

Photovoltaic solar panels convert sunlight to electricity in the form of direct current; therefore, a necessary component of every photovoltaic system is an inverter to convert the electricity to usable alternating current. There are various commercially available inverter technologies manufactured today such as microinverters, string inverters, and central inverters, as well as module level power electronic devices such as DC optimizers that are capable of improving system performance in string and central inverter systems. This thesis compares the performance and economics of five different inverter and module level power electronic systems through model simulation using Helioscope software. The five alternatives …

Design, Fabrication, And Reliability Effects Of Additively Manufactured First Level Compliant Interconnects For Microelectronics Application, Tumininu David Olatunji

Graduate Theses and Dissertations

Semiconductor packaging and development is greatly dependent on the magnitude of interconnect and on-chip stress that ultimately limits the reliability of electronic components. Thermomechanical related strains occur because of the coefficient of thermal expansion mismatch from different conjoined materials being assembled to manufacture a device. To curb the effect of thermal expansion mismatch between conjoined parts, studies have been done in integrating compliant structures between dies, solder balls, and substrates. Initial studies have enabled the design and manufacturing of these structures using a photolithography approach which involves a high number of fabrication steps depending on the complexity of the structures …