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Articles 31 - 45 of 45

Full-Text Articles in Other Electrical and Computer Engineering

Skin Effect Suppression In Infrared-Laser Irradiated Planar Multi-Walled Carbon Nanotube/Cu Conductors, Kamran Keramatnejad, Yang Gao, Yunshen Zhou, Hossein Rabiee Glogir, Mengmeng Wang, Yongfeng Lu Oct 2015

Skin Effect Suppression In Infrared-Laser Irradiated Planar Multi-Walled Carbon Nanotube/Cu Conductors, Kamran Keramatnejad, Yang Gao, Yunshen Zhou, Hossein Rabiee Glogir, Mengmeng Wang, Yongfeng Lu

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

Skin effect suppression in planar multi-walled carbon nanotube (MWCNT)/Copper (Cu) conductors was realized at the 0-10 MHz frequency range through infrared laser irradiation of MWCNTs, which were coated on the surface of the Cu substrate via the electrophoretic deposition (EPD) method. The effect of laser irradiation and its power density on electrical and structural properties of the MWCNT/Cu conductors was investigated using a wavelength-tunable CO2 laser and then comparing the performance of the samples prepared at different conditions with that of pristine Cu. The irradiation at λ=9.219 μm proved to be effective in selective delivery of energy towards depths close …


Bifacial Si Heterojunction-Perovskite Organic-Inorganic Tandem To Produce Highly Efficient (Η T * ~ 33%) Solar Cell, Reza Asadpour, Raghu Vamsi Krishna Chavali, Mohammad Ryyan Khan, Muhammad Ashraful Alam Jan 2015

Bifacial Si Heterojunction-Perovskite Organic-Inorganic Tandem To Produce Highly Efficient (Η T * ~ 33%) Solar Cell, Reza Asadpour, Raghu Vamsi Krishna Chavali, Mohammad Ryyan Khan, Muhammad Ashraful Alam

Department of Electrical and Computer Engineering Faculty Publications

As single junction photovoltaic (PV) technologies both Si heterojunction (HIT) and perovskite based solar cells promise high efficiencies at low cost. Intuitively a traditional tandem cell design with these cells connected in series is expected to improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics however we find that a traditional series connected tandem design suffers from low JSC due to band-gap mismatch and current matching constraints. Specifically a traditional tandem cell with state-of-the-art HIT ( η=24% ) and perovskite ( η=20% ) sub-cells provides only a modest tandem efficiency of ηT~ 25%. …


Ultraviolet Led Biofouling Mitigation, Andrew Lam Jun 2014

Ultraviolet Led Biofouling Mitigation, Andrew Lam

Computer Engineering

The goal is to determine if low-cost UV LEDs can mitigate marine biofouling on small glass or acrylic camera lenses. A microprocessor-controlled experimental setup to control the illumination of low-cost UV LEDs of various wavelength and packaging was fashioned. The system consists of a programmed microcontroller, a manufactured LED breakout interface, and a submergible UV LED array enclosed in a borosilicate glass tube. A preliminary qualitative assessment of four different UV LEDs was conducted during a three-week deployment of the experimental setup in the raw seawater system at the Cal Poly Center for Costal and Marine Sciences in Avila Beach, …


Mos Current Mode Logic (Mcml) Analysis For Quiet Digital Circuitry And Creation Of A Standard Cell Library For Reducing The Development Time Of Mixed Signal Chips, David Marusiak Jun 2014

Mos Current Mode Logic (Mcml) Analysis For Quiet Digital Circuitry And Creation Of A Standard Cell Library For Reducing The Development Time Of Mixed Signal Chips, David Marusiak

Master's Theses

Many modern digital systems use forms of CMOS logical implementation due to the straight forward design nature of CMOS logic and minimal device area since CMOS uses fewer transistors than other logic families. To achieve high-performance requirements in mixed-signal chip development and quiet, noiseless circuitry, this thesis provides an alternative toCMOSin the form of MOS Current Mode Logic (MCML). MCML dissipates constant current and does not produce noise during value changing in a circuit CMOS circuits do. CMOS logical networks switch during clock ticks and with every device switching, noise is created on the supply and ground to deal with …


Measurement And Modeling Of Humidity Sensors, Jingbo Tong Jan 2014

Measurement And Modeling Of Humidity Sensors, Jingbo Tong

Theses and Dissertations--Electrical and Computer Engineering

Humidity measurement has been increasingly important in many industries and process control applications. This thesis research focus mainly on humidity sensor calibration and characterization. The humidity sensor instrumentation is briefly described. The testing infrastructure was designed for sensor data acquisition, in order to compensate the humidity sensor’s temperature coefficient, temperature chambers using Peltier elements are used to achieve easy-controllable stable temperatures. The sensor characterization falls into a multivariate interpolation problem. Neuron networks is tried for non-linear data fitting, but in the circumstance of limited training data, an innovative algorithm was developed to utilize shape preserving polynomials in multiple planes in …


Comprehensive Mapping And Benchmarking Of Esaki Diode Performance, David John Pawlik Aug 2013

Comprehensive Mapping And Benchmarking Of Esaki Diode Performance, David John Pawlik

Theses

The tunneling-FET (TFET) has been identified as a prospective MOSFET replacement technology with the potential to extend geometric and electrostatic scaling of digital integrated circuits. However, experimental demonstrations of the TFET have yet to reliably achieve drive currents necessary to power large scale integrated circuits. Consequentially, much effort has gone into optimizing the band-to-band tunneling (BTBT) efficiency of the TFET. In this work, the Esaki tunnel diode (ETD) is used as a short loop element to map and optimize BTBT performance for a large design space. The experimental results and tools developed for this work may be used to (1) …


Low-Power Self-Sustaining Schedule Display, Samuel (Sam) August Jun 2011

Low-Power Self-Sustaining Schedule Display, Samuel (Sam) August

Electrical Engineering

The completed project is an Amazon Kindle, powered by a USB solar charger, running a student designed program to display a weekly schedule for a faculty member.  The purpose of the project was to design a sustainable electronic schedule display for use outside a faculty office.  It was designed in the hopes that faculty members could more easily update their schedules, and possibly allow for students to schedule appointments.  The program was designed using Java and the solar-charger was designed using a solar cell, Schottky diode, and a USB to micro-B USB cable.


Maximum Current In Nitride-Based Heterostructure Field-Effect Transistors, A. Koudymov, H. Fatima, Grigory Simin, J. Yang, M. Asif Khan, A. Tarakji, X. Hu, M. S. Shur, R. Gaska Apr 2002

Maximum Current In Nitride-Based Heterostructure Field-Effect Transistors, A. Koudymov, H. Fatima, Grigory Simin, J. Yang, M. Asif Khan, A. Tarakji, X. Hu, M. S. Shur, R. Gaska

Faculty Publications

We present experimental and modeling results on the gate-length dependence of the maximum current that can be achieved in GaN-based heterostructurefield-effect transistors(HFETs) and metal–oxide–semiconductor HFETs (MOSHFETs). Our results show that the factor limiting the maximum current in the HFETs is the forward gate leakage current. In the MOSHFETs, the gate leakage current is suppressed and the overflow of the two dimensional electron gas into the AlGaN barrier region becomes the most important factor limiting the maximum current. Therefore, the maximum current is substantially higher in MOSHFETs than in HFETs. The measured maximum current increases with a decrease in the gate …


Si3N4/Algan/Gan-Metal-Insulator-Semiconductor Heterostructure Field-Effect Transistors, X. Hu, A. Koudymov, Grigory Simin, J. Yang, M. Asif Khan, A. Tarakji, M. S. Shur, R. Gaska Oct 2001

Si3N4/Algan/Gan-Metal-Insulator-Semiconductor Heterostructure Field-Effect Transistors, X. Hu, A. Koudymov, Grigory Simin, J. Yang, M. Asif Khan, A. Tarakji, M. S. Shur, R. Gaska

Faculty Publications

We report on a metal–insulator–semiconductor heterostructurefield-effect transistor (MISHFET) using Si3N4 film simultaneously for channel passivation and as a gate insulator. This design results in increased radio-frequency (rf) powers by reduction of the current collapse and it reduces the gate leakage currents by four orders of magnitude. A MISHFET room temperature gate current of about 90 pA/mm increases to only 1000 pA/mm at ambient temperature as high as 300 °C. Pulsed measurements show that unlike metal–oxide–semiconductor HFETs and regular HFETs, in a Si3N4 MISHFET, the gate voltage amplitude required for current collapse is much higher …


Mechanism Of Radio-Frequency Current Collapse In Gan-Algan Field-Effect Transistors, A. Tarakji, Grigory Simin, N. Ilinskaya, X. Hu, A. Kumar, A. Koudymov, J. Yang, M. Asif Khan, M. S. Shur, R. Gaska Apr 2001

Mechanism Of Radio-Frequency Current Collapse In Gan-Algan Field-Effect Transistors, A. Tarakji, Grigory Simin, N. Ilinskaya, X. Hu, A. Kumar, A. Koudymov, J. Yang, M. Asif Khan, M. S. Shur, R. Gaska

Faculty Publications

The mechanism of radio-frequency current collapse in GaN–AlGaN heterojunctionfield-effect transistors(HFETs) was investigated using a comparative study of HFET and metal–oxide–semiconductor HFET current–voltage (I–V) and transfer characteristics under dc and short-pulsed voltage biasing. Significant current collapse occurs when the gate voltage is pulsed, whereas under drain pulsing the I–V curves are close to those in steady-state conditions. Contrary to previous reports, we conclude that the transverse electric field across the wide-band-gap barrier layer separating the gate and the channel rather than the gate or surface leakage currents or high-field effects in the gate–drain spacing is responsible for the current collapse. We …


Effect Of Gate Leakage Current On Noise Properties Of Algan/Gan Field Effect Transistors, S. L. Rumyantsev, N. Pala, M. S. Shur, R. Gaska, M. E. Levinshtein, M. Asif Khan, Grigory Simin, X. Hu, J. Yang Dec 2000

Effect Of Gate Leakage Current On Noise Properties Of Algan/Gan Field Effect Transistors, S. L. Rumyantsev, N. Pala, M. S. Shur, R. Gaska, M. E. Levinshtein, M. Asif Khan, Grigory Simin, X. Hu, J. Yang

Faculty Publications

The effect of the gate leakage current fluctuations on noiseproperties of AlGaN/GaN heterostructurefield effect transistors(HFETs) has been studied in conventional HFET structures and in AlGaN/GaN metal-oxide-semiconductorheterostructurefield effect transistors (MOS-HFETs). The comparison of the noiseproperties of conventional AlGaN/GaN HFETs and AlGaN/GaN MOS-HFETs fabricated on the same wafer, allowed us to estimate the contribution of the gate currentnoise to the HFET’s output noise. The effect of the gate current fluctuations on output noiseproperties of HFETs depends on the level of noise in the AlGaN/GaN HFETs. For the transistors with a relatively high magnitude of the Hooge parameter α∼10−3, even a …


Algan/Gan Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors On Sic Substrates, M. Asif Khan, X. Hu, A. Tarakji, Grigory Simin, J. Yang, R. Gaska, M. S. Shur Aug 2000

Algan/Gan Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors On Sic Substrates, M. Asif Khan, X. Hu, A. Tarakji, Grigory Simin, J. Yang, R. Gaska, M. S. Shur

Faculty Publications

We report on AlGaN/GaN metal–oxide–semiconductor heterostructurefield-effect transistors (MOS-HFETs) grown over insulating 4H–SiC substrates. We demonstrate that the dc and microwave performance of the MOS-HFETs is superior to that of conventional AlGaN/GaN HFETs, which points to the high quality of SiO2/AlGaNheterointerface. The MOS-HFETs could operate at positive gate biases as high as +10 V that doubles the channel current as compared to conventional AlGaN/GaN HFETs of a similar design. The gate leakage current was more than six orders of magnitude smaller than that for the conventional AlGaN/GaN HFETs. The MOS-HFETs exhibited stable operation at elevated temperatures up to 300 …


Deriving Of Single Intensive Picosecond Optical Pulses From A High-Power Gain-Switched Laser Diode By Spectral Filtering, S. N. Vainshtein, Grigory Simin, J. T. Kostamovaara Oct 1998

Deriving Of Single Intensive Picosecond Optical Pulses From A High-Power Gain-Switched Laser Diode By Spectral Filtering, S. N. Vainshtein, Grigory Simin, J. T. Kostamovaara

Faculty Publications

Single 25 ps/16 W optical pulses were achieved by spectral filtering from a multiheterostructure gain-switched laser diode with its quasisteady-state modes suppressed by a factor of 103 as compared with the peak power. A significant transient spectrum broadening makes this possible provided that a very high dI/dt rate of the pumping current pulse is used. A simple numerical model is suggested which describes adequately both the spectral and transient features of the observed phenomenon. It follows from the model that single picosecond optical pulses can be obtained from any type of high power semiconductor laser.


A Stochastic Model For Crystal-Amorphous Transition In Low Temperature Molecular Beam Epitaxial Si(111), R. Venkatasubramanian, Suresh Gorantla, S. Muthuvenkatraman, Donald L. Dorsey Dec 1996

A Stochastic Model For Crystal-Amorphous Transition In Low Temperature Molecular Beam Epitaxial Si(111), R. Venkatasubramanian, Suresh Gorantla, S. Muthuvenkatraman, Donald L. Dorsey

Electrical & Computer Engineering Faculty Research

Molecular beam epitaxial Si (111) grown below a certain temperature result in amorphous structure due to the limited surface mobility of atoms in finding correct epitaxial sites. In spite of many experimental and theoretical studies, the mechanism of crystal‐amorphous transition and its dynamics related to the growth conditions are not well understood. In this article, we present a theoretical model based on the formation of stacking fault like defects as a precursor to the amorphous transition of the layer. The model is simulated based on a stochastic model approach and the results are compared to that of experiments for temperatures …


A Study Of The Plating Prohibitive Properties Of Various Separators, Bruno J. Pozorski May 1931

A Study Of The Plating Prohibitive Properties Of Various Separators, Bruno J. Pozorski

Bachelors’ Theses

The problem of this thesis is to study the plating prohibitive properties of the various materials commonly used in the manufacturing of separators, and to indicate which material would be most serviceable and feasible in a separator. At one time positives and negatives were kept not more than 0.25 inches apart, with the idea of reducing the intervening layers of electrolyte, and, therefore, the internal resistance of the cell, as much as possible. It was, however, found that the output could actually be increased by putting the plates at greater distances, the fact being that the larger bulk of solution …