ECE Distinguished Lecture: ‘NEMO5, a Nanoelectronics Modeling Tool from Basic Physics to Real Devices and to Global Impact on nanoHUB.org’

photo of gerhard klimeck
The downscaling of electronic devices has reached the range where the number of atoms in critical dimensions is countable, geometries are formed in three dimensions and new materials are being introduced. Under these conditions one can argue that the overall geometry constitutes a new material that cannot be found as such in nature and the distinction between new device and new material are blurry. The interactions of electronic, photons, and lattice vibrations are now governed by these new material properties and longer-range interaction mechanisms such as strain and gate fields. The Nanoelectronic Modeling tool suite NEMO5 is aimed to comprehend the critical multi-scale, multi-physics phenomena and deliver results to engineers, scientists, and students through efficient computational approaches. NEMO5’s general software framework easily includes any kind of atomistic model and is, insofar, able to compute atomistic strain, electronics band structures, charge density, current and potential, Schrödinger eigenvalues and wave-functions, phonon spectra, and non-equilibrium Green functions (NEGF) transport for a large variety of semiconductor materials and the software is entirely parallelized. We believe that such modeling capability is not available in any other modeling tool at this time.

The work conducted in the group spans a wide range of devices and concepts from work with the leading semiconductor industries on technologies for the sub 10nm transistors, over optical devices to improve lighting, to foundational device physics for quantum computing in Silicon. This presentation overviews various aspects of NEMO5 capabilities and interactions with academia and industry.

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ECE grad student Harald Schafer part of award-winning team at the TMP’s New Venture Competition

nvc 2016 logo
Six student teams from UCSB take home more than $40,000 in cash prizes at the 17th New Venture Competition Finals, hosted by the Technology Management Program

ECE’s Schafer partnered with Kelsey Judd and Janek Metzner on team Vibe that won $15,000 for their wearable ultrasonic sensor device that translates information about the environment to a visually impaired user through unique vibration pattern that helps them navigate their surroundings.

Since the beginning of fall, NVC students worked with local entrepreneurs, business executives, and mentors to develop and refine their business ideas. The Finals were the biggest highlight of the New Venture Competition where each team pitches their business ideas to a panel of independent and highly respected judges for a chance to win cash prizes.

Winners of the 2016 New Venture Competition:

  • Grand Prize Award ($12,500): OSMO
  • 2nd Place Award($7,500): Vibe
  • 3rd Place Award ($2,500): EV Match
  • Honorable Mention Award (Sonos prize): Ingrain
  • Citrix Impact Award ($5,000): Vibe
  • Cliff Hannel Innovation Award ($5,000): Opal
  • Elings CNSI Award ($5,000): Ingrain
  • People’s Choice Award ($2,500): Dermachill
  • People’s Choice Award ($2,500): Vibe
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Millimeter and Terahertz Wave Wireless Communications powered by Light Engines

photo of Guillermo Carpintero Photonic Integrated Circuits (PICs) are key enablers for the development of “light engines”, photonic systems on a chip for specific functionalities in which photonics outperform electronics, keeping a chip form factor. Photonics-based technologies are leading the access to high frequency ranges, within the millimeter (30 to 300 GHz) and terahertz (300 GHz to 3 THz) bands. To date, multiple photonic techniques have been proposed for the generation of signals within these frequency bands with different performance in terms of the maximum frequency that can be generated, the frequency tuning range and the stability. An additional advantage of the use of photonics technologies is to enable the distribution of high-frequency RF signals over long distances using optical fibers, an extremely interesting feature that can ultimately allow for the convergence of wired (fiber-optic) and wireless communication networks, with a seamless integration in terms of data rates and modulation formats.

The presentation will cover different approaches using Photonic Integrated Circuits, with emphasis on either the full integration of all the transmitter components on a chip or the use of Generic Photonic Integration Technology Platforms, through Multi-Project Wafer runs. We will discuss the performance of different light engines which were designed to implement the most common signal generation techniques, optical heterodyne and mode-locked pulsed sources. Using these components we have achieved real-time error-free wireless data transmission of uncompressed HDTV signal over one meter. We will discuss a novel approach using a dual wavelength source for optical heterodyning based on hybrid integration of active InP elements and thermo-optically tunable polymer waveguide structures, having a tuning range over 20 nm, enabling the generation of signals from tenths of GHz up to several THz with MHz resolution.

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Computer Engineering – ECE 189A/B Capstone Project Presentation Day 2016

Computer Engineering – ECE 189A/B CAPSTONE PROJECT PRESENTATION DAY – JUNE 2 (THU) 2016

photo of students with project
During their senior year Computer Engineering students take either the CS 189 or ECE 189 Senior Computer Systems Project aka “Capstone” course. Every year at the end of the Spring quarter the ECE 189 final projects are presented at a full-day industry sponsored and judged event where student groups publicly present their projects and participate in an outdoor lunchtime project demonstration and poster session.

EVENT SCHEDULE OVERVIEW

  • Morning (9:00am-12:00pm) ESB 1001 – opening remarks & 4 project presentations
  • Lunch (12:00-1:00pm) ESB Courtyard – Project Posters & FREE Pizza
  • Afternoon (1:00-3:30pm) ESB 1001 – 4 project presentations
  • Best Project Award Presentation (3:30pm) ESB Courtyard Stairway

 

MORNING SESSION in ESB 1001 — 9:00am-12:00pm
9:00 am — Opening Remarks: Dr. John Johnson, Instructor
9:15 – ChessMate: an interactive, LED illuminated chess board that enhances player experience with various digital board augmentations
Team: Jeremiah Schultz, Philip Lo, Jason Dahn, Alex Babicz
9:45 – Soil Smart: a wireless sensor network that monitors and records soil conditions
Team: Jacob Adams, James Cornell, Jesus Vega, Peter Marcelo, Ricardo Morones
10:15 – OstraCam: an underwater machine vision platform that records bioluminescent plankton using cameras and external sensors w/ the goal to build a model of the individual emissions
Team: Bobby Heyer, Caio Motta, Eddie Franco, Jovan Hernandez, Molly Smith
11:00 – BULB by SONOS: a light bulb speaker that connects to any light bulb socket and is controlled via WiFi and reproduces audio in conjunction with lighting effects
Team: Nico Soberanes, Zaira Tomayeva, Jose Maun, Randy Picchini, Eric Jin

POSTERS & PIZZA LUNCH in the ESB Courtyard — 12:00-1:00pm

AFTERNOON SESSION in ESB 1001 — 1:00-3:30pm
1:00 – UCSB Hyperloop Drive: a communications, telemetry, and control unit for UCSB’s entry into SpaceX’s Hyperloop Pod Competition
Team: Celeste Bean, Connor Buckland, Benjamin Hartl, Cam McCarthy, Connor Mulcahey
1:45 – dVA: a software tool for analyzing and visualizing test data taken from semiconductor processes
Team: Sam Dowell, Blake Hall, Christopher Hindman
2:15 – Heart Buddy: a portable armband that provides help before or as soon as an accident occurs via sensors such as heart beat, body orientation, and acceleration
Team: Jairo Hernandez, Jose Reyes, Andrew Pagan, Andrew Villagomez
2:45 – D.A.T.A. (Dynamic Automated Tuning Air) Suspension System: an air suspension system designed to automatically facilitate smooth riding and prevent damage to the vehicle body
Team: Jonathan Rodriguez, Evan Hsiao, George Pina, Elton Wu

BEST PROJECT AWARDS in the ESB Courtyard Stairway — 3:30pm

 

photo of sponsor logos

 

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A Modular Approach to Analyzing Biological Networks

Biological networks are inherently very complex, consisting of several entities reacting in a nonlinear fashion. While there has been a lot of study into the behavior of these discrete biological entities, rarely can biological function be attributed to a single molecular species alone. Therefore, there is a need for the recognition of functional components in biological network organization. These components are discrete entities whose biological function is separable from that of other components.

In this work, we address the decomposition of biochemical networks into functional modules that preserve their dynamic properties upon interconnection with other modules, which permits the inference of network behavior from the properties of its constituent modules. The modular decomposition method developed here also has the property that any changes in the parameters of a chemical reaction only affect the dynamics of a single module. To illustrate our results, we define and analyze a few key biological modules that arise in gene regulation, enzymatic networks, and signaling pathways, and show how modular decomposition is useful to predict network properties.

We then use this modular decomposition method to analyze the p53 network, which plays a key role in tumor suppression in many organisms. We study the evolution of the p53 core regulation network and conduct a formal analysis of the different network configurations that emerge in the evolutionary path to complexity from putative primordial organisms to modern-day vertebrates. We develop an algorithm to solve the system of equations that describe the network behavior by interconnecting the network modules systematically, as these equations are typically difficult to solve using standard numerical solvers. In the process, we qualitatively compare the distinct bifurcation behaviors that each network can exhibit. We demonstrate how our novel model for the core regulation network matches experimentally observed phenomena in human cells, and contrast this with the plausible behaviors that ancestral organisms can admit. Specifically, we show that the complexity of the p53 network in humans and evolved vertebrates permits a wide range of behaviors that can bring about distinct cell fate decisions in response to DNA damage, but that this is not the case for primordial organisms.

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III-V-on-silicon Photonic Integrated Circuits for Optical Communication and Sensing

Gunther Roelkens In this talk I will present the research carried out in the Photonics Research Group of Ghent University / imec on silicon photonic integrated circuits (PICs) for optical communication and sensing. This includes all-silicon PICs comprising high speed optical modulators and photodetectors based on the integrtion of Ge, the integration of III-V sources through die-to-wafer bonding and hetero-epitaxial growth addressing a broad wavelength range from 850 nm to 2.5 um, and the co-integration with electronic integrated circuits for advanced silicon photonic transceivers.

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Researchers Yon Visell and Katja Seltmann co-anchor “Unknown Territories” on the UCSB radio station

photo of seltmann and visell
CCBER’s Seltmann and ECE’s Visell tap current scientific literature for their weekly cultural arts program on KCSB radio

UC Santa Barbara entomologist Katja Seltmann has an alter ego. She goes by the name Irene Moon, and she came into being decades ago when Seltmann first started creating science-inspired performance art and DJing on the radio as an undergraduate student at the University of Georgia.

Seltmann — or, rather, her Moon persona — is still riding the airwaves, joined by her partner, Yon Visell. Together they co-anchor “Unknown Territories,” an hour long program with the topic of all things science.

With diverse science backgrounds (Seltmann is the Katherine Esau Director of UCSB’s Cheadle Center for Biodiversity and Ecological Restoration (CCBER) and Visell is an assistant professor in the campus’s Department of Electrical and Computer Engineering, Department of Mechanical Engineering and Media Arts and Technology Graduate Program), the pair brings an unusual bent to their weekly radio show, which airs Tuesdays at 9 a.m.

“We both love radio as a medium for expressing ideas and for education, and it’s really fun to do,” Seltmann said. “This show has been great for us because one of the things about being a researcher is that you have to keep up with the literature. Each week, we read a variety of journals, including Science, Nature and the Proceedings of the National Academy of Sciences, to choose our topics. We also check social media to see what’s hot and what people are talking about.”

The couple’s broad range of expertise — biology, physics, engineering and cognitive sciences — informs the program’s content, which focuses on topical discussions aimed at communicating ideas about science through entertaining yet critical discourse.

According to Seltmann, “Unknown Territories” fills a critical niche. “We strive to promote science communications as well as to develop a larger dialogue with the community about scientific issues,” she noted. “And because KCSB is a public radio station that streams on the Internet, that community is not just Santa Barbara. There is a connection to the larger world. We feel strongly that everyone in society should be empowered to learn, evaluate and participate in science.”

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Novel mid-infrared materials and devices on InP: from metamorphic lasers to self-assembled nanocomposites

Laser diodes (LDs) emitting in the mid-infrared (mid-IR) spectral region (λ= 2 – 3 μm) are important for applications including molecular spectroscopy and gas detection. Quantum cascade lasers on InP have reached λ=3.0 μm continuous wave (CW) lasing at room temperature (RT), while type-I InAs quantum well (QW) LDs have reached λ= 2.4 μm. However, due to extremely high strain in the active regions for both technologies, demonstration of CW RT lasing at 2.4 – 3.0 μm remains difficult for InP-based lasers. A metamorphic InAsxP1-x graded buffer on InP can perform multiple functions in addressing this challenge, as it not only increases the critical thickness of InAs QWs to enable longer wavelength emission, but also functions as graded-index bottom cladding for optical confinement. We demonstrate room-temperature metamorphic type-I QW LDs on InP that take advantage of such multi-functional metamorphic buffers to achieve lasing at λ= 2.76 μm. The metamorphic LDs were grown on n-InP (001) substrates by solid source molecular beam epitaxy (MBE). We fabricated and tested 10 µm ridge-waveguide LDs, observing pulsed mode lasing up to 300 K at λ = 2.76 μm. The threshold current density at 77 K was 200 A/cm2 and increased to 14 kA/cm2 at 300 K.

In the second part of my talk, we present self-assembled growth of highly tensile-strained Ge nanostructures, coherently embedded in an InAlAs matrix (i.e. Ge/InAlAs nanocomposite) by using spontaneous phase separation. Ge is a very intriguing material for strain engineered nanocomposites, because strain can dramatically enhance its electrical and optical properties. Here, I employ spontaneous
phase separation during MBE growth as a fundamentally
new approach to forming highly tensile-strained Ge/InAlAs nanocomposite. Transmission electron microscopy reveals a high density of single-crystalline Ge nanostructures coherently embedded in InAlAs without extended defects, and Raman spectroscopy reveals a 3.8% biaxial tensile strain in the Ge nanostructures. I demonstrate that the strain in the Ge nanostructures can be tuned to 5.3% by altering the lattice constant of the matrix material, illustrating the versatility of epitaxial nanocomposites for strain engineering and the largest biaxial tension realized in Ge to date; the cross-over from indirect to direct is predicted at ~2% biaxial tension. Photoluminescence and electroluminescence results are then discussed to illustrate the potential for realizing devices based on this novel nanocomposite material.

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Transparent Conducting Oxide Clad Limited Area Epitaxy Semipolar III-nitride Laser Diodes

photo of Anisa MyzaferiBasal plane III-nitride laser diodes have been commercialized for wide ranging technologies, including pico projectors for solid state RGB displays, optical data storage and automotive headlights. Active research is focused in solid state lighting and visible light communications. Despite widespread commercialization, c-plane devices are affected by the inherent spontaneous and piezoelectric polarizations of the basal plane. These polarization effects are significantly reduced in semipolar planes of GaN, creating a vast design space for III-nitride optoelectronic devices.

III-nitride semipolar laser design and performance are considerably affected by the material composition and growth conditions of the cladding layers. The bottom cladding design is limited by stress relaxation of ternary alloys while the top cladding is limited by the growth time and temperature of the p-type (Al,In,Ga)N layers. These design limitations have been independently addressed by using limited area epitaxy (LAE) to enable n-AlGaN bottom cladding layers and by using thin p-GaN and transparent conducting oxide (TCO) top cladding layers.

In this work, we investigate a new laser design that simultaneously incorporates LAE-enabled n-AlGaN bottom cladding and thin p-GaN and TCO top cladding layers in (202 ̅1) III-nitride laser structures. We evaluate the performance of two different TCOs as the top cladding layer: indium-tin-oxide (ITO) and zinc oxide (ZnO). Thorough optical modeling of the LAE-TCO laser design will be discussed for various Al compositions in the LAE-enabled n-AlGaN bottom cladding and varying p-GaN thicknesses in the top cladding. The LAE-TCO laser design was first demonstrated using ITO as the top cladding layer, with pulsed lasing achieved at 446 nm with a threshold current density of 8.5 kA/cm2 and a threshold voltage of 8.4 V. Insights from the optical modeling in conjunction with improvements in the LAE-TCO laser fabrication process led to the demonstration of the LAE-TCO design using ZnO as the top cladding layer, with pulsed lasing achieved at 445 nm with a threshold current density of 5.6 kA/cm2 and a threshold voltage of 6.7 V. This notable improvement in threshold current density and voltage led to the first continuous wave (CW) operation of blue (202 ̅1) LAE-ZnO laser structures.

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The Origin of 1/f Noise, Maybe

The origin of 1/f noise (sometimes referred to as flicker or pink noise) in semiconductor devices has not been convincingly explained since it was first reported by Schokly in 1918. This paper presents a possible explanation namely that the noise arises due to turbulence in the flow of the electron (or hole) fluid/gas in the sample. Turbulence in fluid or gas flow arises naturally from the convective forces imposed by a fluid¹s viscosity. Historically, transport in semiconductor materials has been modelled using linear equations of drift and diffusion that do not exhibit turbulence. Transport of gases and fluids in the discipline of hydrodynamics also uses the equations of drift and diffusion, but in addition includes the Navier-Stokes equation to describe flows that are turbulent. The Navier-Stokes equation naturally produces turbulence as the Reynold¹s number exceeds a certain range. For a uniform flow the critical Reynolds number is large several thousand. However, for narrow jets impinging upon a reservoir, the Reynolds number may be more than two orders of magnitude smaller. Scattering of electron flow by phonons, impurities, and other carriers may precipitate turbulent flow to arise at low values of the Reynolds number in semiconductors. In this paper we report on Navier-Stokes simulations of the spectral properties of turbulent flows showing that they are consistent with a 1/f spectrum. We also report on a series of measurements of photodiodes as a function of illumination intensity to observe how the 1/f properties vary with current so that in the future we can compare that variation to our simulations.

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