Category Archives: Events

Understanding the High-Frequency Behavior of Nanoscale Devices

DR. DIEGO KIENLE
UNIVERSITY OF BAYREUTH; BAYREUTH, GERMANY
MONDAY, APRIL 22
9:30 AM – 10:30 AM
STUDENT UNION – HATCH D

Talk Abstract:  At present there is a significant need to model and understand dynamic quantum transport in realistic nanoscale devices including non-idealities e.g. due to scattering to ultimately guide the development of novel quantum devices operating at terahertz frequencies, even exploiting plasmonic waves for THz sensing and emission.  In approaching this goal, in this talk I provide a broader introduction into the field of the modeling of nanoscale materials and devices. Particular attention is put on the transport problem under time-dependent biases and on the challenges to solve it as various physical aspects need to be simultaneously captured by a suitable model, some of which are 1) the handling the quantum mechanics of transport of open systems including the non-equilibrium physics under finite bias, 2) the complex dielectric environment typical for realistic devices, and 3) most importantly the self-consistent, dynamic coupling of the space-dependent AC charge and potential; the latter being essential to capture the plasmonic response of the system, in general.

Biographical Sketch:   Diego Kienle received his PhD from the Research Center Jülich and the University of Saarland, Germany, in theoretical physics. After postdoctoral appointments with the Electrical and Computer Engineering Department at Purdue University and the Material Science Department at Sandia National Laboratories in California, he is currently with the Institute of Theoretical Physics at the University of Bayreuth. His research interest are in the theory, modeling, and simulation of AC quantum electronic transport in nanoscale materials and devices with focus on the understanding of the quantum dynamic processes in low-dimensional materials and their potential application in solid-state based terahertz devices. His past research interest are in the theory and modeling of complex fluids by means of Brownian dynamics with focus on many-body hydrodynamic interaction effects in diluted polymer solutions.

Fascinating Applications of Metamaterials and Plasmonics: Cloaking, Sensing, Energy Harvesting and Wireless Communication

PAI-YEN CHEN
UNIVERSITY OF TEXAS – AUSTIN
THURSDAY, APRIL 18
9:30 AM – 10:30 AM
STUDENT UNION BUILDING – HATCH D

Talk Abstract: 
Metamaterials are artificial composite materials engineered to have novel electromagnetic properties, unavailable in nature and radically different from their constituent components. Plasmonics has further enriched and enhanced the field of metamaterials, opening new possibilities to manipulate and confine light at nanoscale dimensions, unthinkable only a few years ago. In my talk, I will describe my recent research efforts on plasmonic materials and metamaterials and their practical uses in energy harvesting, sensing, communication and wireless health systems based on novel electromagnetic phenomena and electronic physics in the spectral range from radio frequencies (RF) and microwaves, terahertz (THz) to visible light.

I will discuss theory and practice of how the plasmonic materials and metamaterials can ultimately manipulate the relevant electromagnetic constitutive parameters, including permittivity, permeability, nonlinear susceptibility and conductivity, to offer new promises in nanoscale nonlinear optics and information processing, highly-efficient solar and thermal energy harvesting and conversion systems, and metamaterial-based/-inspired cloaks and electrically-small antennas used for enhancing the sensitivity and signal-to-noise ratio in future RF wireless communication and sensor networks. As an extreme case of signal manipulation at the “atomic” scale, I will discuss how the gate-tunable surface plasmon polaritons in graphene nanodevices may enable the THz frequency-configurable antennas and beam-steerable phased arrays. I will conclude my talk discussing the integration of graphene-based THz frequency synthesizers, antennas and circuit components to realize “all-graphene” THz transceivers and sensors of great interest in data transformation, sensing, actuation and communications of nanosystem.

Biographical Sketch:
Pai-Yen Chen is currently a PhD Candidate under the supervision of Prof. Andrea Alù in the Department of Electrical and Computer Engineering at The University of Texas at Austin. His scientific research is in multidisciplinary areas of physical and wave electronics in the spectral range from microwaves, terahertz (THz) to visible light. His doctoral work mainly focuses on metamaterials, nanomaterials and plasmonics, as well as their applications in wireless communications, radar and sensors, electronic warfare, thermal and solar energy harvesting and conversion, biological and medicine detection. Prior to joining UT Austin (2006-2009), he studied extensively vacuum nanoelectronics and semiconductor device modeling, parameter extraction, characterization and fabrication techniques at National Nano Device Laboratories (NDL), Taiwan. Mr. Chen has published approximately 35 papers in peer-reviewed journals (3 journal coverages), 28 conference proceedings, and 2 book chapters. He is a reviewer of over 10 scientific journals.

Pai-Yen Chen received his M.S. and B.S. degrees in Electro-optical Engineering and Mechanical Engineering from National Chiao Tung University, Taiwan, in 2000 and 2004, respectively. His honors and awards include the 2005 United Microelectronics Corp. (UMC) Scholarship, Chinese Phi Tau Phi Honorable Member (officially nominated in 2006), 2009 Taiwanese Ministry of Education Study Abroad Award, 3rd prize Student Contest Award in Metamaterials’2011, 3rd prize Student Contest Award in 2012 USNC-URSI National Radio Science Meeting, Finalist and Honorable Mention Student Contest Award in 2010 and 2011, 2013 IEEE Antennas and Propagation Symposium. In 2012, he received the Donald D. Harrington Dissertation Fellowship, which is the most prestigious fellowship to graduate students bestowed by the Harrington Society at University of Texas at Austin.

Metamaterial-Based Design: The Grand Unification Scheme for Electromagnetic, Acoustic and Hydrodynamic Applications

DR. YAROSLAV URZHUMOV
DUKE UNIVERSITY
MONDAY, APRIL 8
9:30 AM – 10:30 AM
STUDENT UNION BUILDING – HATCH D

Talk Abstract:  Artificially created media, or metamaterials, can derive their properties both from their material components and microscopic structure. Recent boom in semiconductor photonics, for example, has to do both with the emergence of novel nanotechnologies capable of sculpting the microstructure, and the dramatic increase in our computational capabilities that enabled the design of functional structures. The relationship between nanotechnology and computational design became truly synergistic when a powerful methodology, “transformation optics”, was added to our toolbox. Transformation optics complemented with tunable metamaterials promises ultimate control over the dynamics of electromagnetic fields, and paves the way towards devices that would seem impossible just a few decades ago. I will present our recent experimental results for several such devices: radio-frequency metamaterial superlenses for wireless power transfer and polymer-based, low-loss microwave invisibility cloaks. How to miniaturize transformation optical devices for higher-frequency applications, including THz and optical, and how to integrate them with the popular silicon-chip platform will be discussed.

Metamaterials are quickly expanding their influence on other fields, among which are acoustics, thermodynamics, solid state physics and hydrodynamics. Some of the fabrication techniques originally developed for microwave and optical metamaterials are beginning to impact these novel fields. Additive manufacturing, or “rapid prototyping”, is particularly cheap yet accurate enough to fabricate acoustic metamaterials for audible frequencies, where they show promise for acoustic cloaking and imaging. Theoretical challenges with porting transformation optics to the realms of elastodynamics and hydrodynamics are discussed, and interim solutions based on topology optimization are presented.

Biographical Sketch:  Yaroslav Urzhumov is an Assistant Research Professor of Electrical and Computer Engineering at Duke University, where he works since 2009. He received his Ph.D. in Physics from the University of Texas at Austin, where he defended his dissertation in the field of optical metamaterials under supervision of Prof. Gennady Shvets in 2007. Dr. Urzhumov’s scientific career started at the Institute of Theoretical and Experimental Physics in Moscow, Russia, where he worked in the group of Prof. Imshennik on problems of particle astrophysics and fusion plasmas. Between now and then, Dr. Urzhumov had also worked as an application engineer for COMSOL Inc., a multiphysics simulation software company. Urzhumov’s research interests include theoretical and applied aspects of metamaterials for optics and photonics, microwave and low-frequency electromagnetism, as well as acoustics and fluid dynamics. In 10 years, he has published over 60 scientific papers, including 40 refereed publications and book chapters, which were cited nearly 900 times with the ISI h-index of 14. His works on metamaterial applications such as optical cloaking, wireless power transfer and wake-free propulsion systems won the cover of Physical Review Letters, were highlighted by ScienceNOW and APS Physics Synopsis, and reported by mass media including MSNBC, Popular Science magazine and The Forbes business news.

 

Emerging Low-Temperature Semiconductor Materials and Devices

DR. KURTIS CANTLEY

UNIVERSITY OF TEXAS – DALLAS
TUESDAY, APRIL 2
9:30 AM – 10:30 AM
STUDENT UNION BUILDING – HATCH D

Talk Abstract:  Low-temperature semiconductor materials and devices provide an excellent platform for applications in the areas of biomedical systems and alternative computation. This work focuses on the use of nano-crystalline silicon (nc-Si) thin-film transistors (TFTs) for circuits fabricated on flexible polymer substrates at temperatures less than 250 °C. Simulation and fabrication of resistance change memories based on nc-Si or HfO2 are also described. Together, these devices enable the creation of neural networks with associative learning, adaptation, and pattern recognition capabilities. Incorporation of such circuits in a back-end-of-line CMOS process is envisioned to augment or complement the digital core by providing efficient processing of complex environmental information. They can also be integrated with various types of sensor arrays for biomedical, military, and consumer electronics.

Biographical Sketch:  Kurtis D. Cantley received the BSEE degree with Honors in 2005 from Washington State University during which time he participated in the National Security Internship Program at Pacific Northwest National Laboratory. He obtained the MSEE degree from Purdue University in 2007 where his research involved simulation of III-V materials in nanoscale transistors. Work toward his PhD in electrical engineering began at the University of Texas at Dallas in 2007 with funding from the National Defense Science and Engineering Graduate (NDSEG) Fellowship. Dr. Cantley completed his PhD in 2011 and has since worked as a postdoctoral research associate in the Department of Materials Science and Engineering at UTD researching artificial neural networks, biological and chemical sensors, and devices for large-area radiation detection.

Extending the Battery-Powered Operating Time of a Wireless Environmental Monitoring System

Ross Butler’s Dissertation Proposal Defense

October 19, 2012
2:00pm – 4:00pm
MEC 106

Advisor:

Dr. Sin Ming Loo

Committee:

Dr. Jennifer Smith

Dr. Vishal Saxena

 

ABSTRACT:

Advances in low-power microelectronics and sensor technologies have enabled the creation of sophisticated environmental monitoring systems capable of operating on battery power. Independence from a power outlet connection opens up many new potential applications, but limited battery life still imposes significant restrictions on a monitoring system’s capabilities and the number of systems that can be economically deployed and maintained. These restrictions have motivated much research into reducing monitoring system energy usage, increasing battery capacity, and harnessing alternative energy sources.  While most of the research focuses on new system design, there is a need for techniques to extend the battery-powered operating time of existing environmental monitoring systems without compromising their sensor data quality.
This thesis explores and develops methods for extending the operating time of an existing air-quality monitoring system. The system contains seven environmental sensors that create a substantial energy demand and make long-term battery operation challenging. The resulting hardware and firmware modifications doubled the system’s battery-powered operating time without significantly reducing its environmental measurement data quality. The addition of an external battery sized to match the system’s form factor increased operating time well past the goal for the intended application. Although the modifications and results presented in this thesis are specific to one environmental monitoring system, the same techniques could be applied to other monitoring systems and to embedded systems in general.

Seeking Cleaner Air – Accessible Air Quality Monitoring and Event Diagnosis

Jim Hall’s Dissertation Proposal Defense

September 6, 2012
9:00am – 11:00am
MEC 301

Advisor:

Dr. Sin Ming Loo

Committee:

Dr. Jim Browning

Dr. Dale Stephenson

Dr. Vishal Saxena

 

ABSTRACT:

Airborne particulate matter has been shown to be associated with morbidity and mortality, and can have an impact on sensitive materials and processes. Understanding the levels and movements of particulate matter in an enclosed space can lead to a reduction in the negative consequences of poor air quality. Furthermore, a system of environmental sensors including particulate matter, selected gases, and other atmospheric factors can be used to provide a real-time assessment of air quality. This assessment can be used to assist in the diagnosis of the source of particulate matter. This dissertation proposal will result in the creation of a framework for the monitoring and diagnosis of air quality events that will assist in the move towards cleaner air. To achieve this goal, a low-cost optical particle counter is created for incorporation into a wireless sensor network (WSN), including the exploration of novel methods for improving the quality of such a sensor. A WSN is developed using the aforementioned sensors, along with a system for data collection and visualization. Finally, a distributed event detection and classification framework is formulated to allow the coupling of human feedback into the system. The prototype system will be tested in real-world environments such as office and residential settings. The results of this work may be leveraged into multiple applications that assist in the diagnosis and treatment of air quality issues that have tangible impact on health and material quality.

Conduction Mechanisms of Ion-conduction, Bridging Memory Devices (CBRAM/PMC/ECM)

Kyle Campbell’s Thesis Defense

May 11, 2012
2:00pm
MEC 309

Committee: Kris Campbell (Advisor), Jim Browning, Vishal Saxena

Abstract:
Electron storage memory devices are approaching the minimum dimensions that are physically possible due to the onward march of Moore’s law. To continue to enable the increased memory densities needed for today’s applications, especially low power, size constrained mobile devices, new memory solutions are needed.  Several candidates are     emerging in this space.  Metal ion-conducting memory devices are being investigated due to excellent scalability, speed and low power.  These devices are part of a memory class called  resistive memory. In the literature they are referred to as CBRAM (conductive bridge random access memory), PMC (programmable metallization cell), ECM (electrochemical    metallization cell), and Atomic Switch. This work seeks to understand the conduction mechanisms that are occurring in switching devices comprised of W/Ge2Se3/Ag, bottom to top, called Ag-only throughout, and in switching devices comprised of W/Ge2Se3/SnSe/Ag/W, bottom to top, called Ag+SnSe throughout. Additionally, the conduction mechanisms in the Ge2Se3memory layer are investigated using devices comprised of W/Ge2Se3/W.  The experimental method used to analyze the devices was DC voltage sweep across multiple temperatures over the range of 300K to 10K.

Dynamic Modeling of Single-Phase Induction Motor Loads

Danyal Mohammadi’s Thesis Defense

April 23, 2012
3:00pm
MEC 301

Committee: Dr. Said-Ahmed Zaid (Advisor), Dr. Jim Browning, Dr. John Chiasson

Abstract:
Single-phase induction machines are found in various appliances such as refrigerators, washing machines, driers, air conditioners and fans. Large concentrations of single-phase induction motor loads such as air conditioners and other motor-compressor loads can adversely impact the dynamic performance of a power system. An understanding of the dynamics of this type of induction machine will definitely improve the current state-of-the art in running power system dynamic studies. In this thesis, a novel approach of modeling a single-phase induction machine is developed that gives credence to the well-know double revolving-field theory. Using standard averaging techniques, a seventh-order augmented  dynamic model is derived using forward- and backward-rotating components. The double-frequency terms causing torque and speed pulsations in the original model can be recovered as a  byproduct of the theory. It is proved that two three-phase induction machines with their stator windings connected in series but with opposite phase sequence have the same dynamical behavior as the averaged single-phase induction machine model. The dynamic and steady-state performance of the single-phase machine is investigated using the new averaged model and compared with the exact model.

Methods and Considerations for Testing Resistive Memories

Adam Johnson’s Thesis Defense

April 10, 2012
3:00pm
MEC 309

Committee: R. Jacob Baker (Advisor), Kristy A. Campbell, Wan Kuang

Abstract:
Resistive random access memory (RRAM) has been the topic of many research papers in   recent years, as companies begin to look for non-volatile alternatives to NAND Flash. The standard testing methodologies for single devices do not work for most of the RRAM technologies, so new methods must be developed. Parasitic capacitance will destroy the device under test without current compliance circuitry.  A test structure with the capability to apply current compliance in either direction was designed, simulated, and tested with electrical results. Pulses greater than 4.0 V were delivered with 100uA current compliance. Parasitic capacitance was kept below 50fF.

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