E3S REU Participants and Projects: 2013
Undergraduate Researcher: Arunima Balan
Major: Chemistry and Physics
Home Institution: Massachusetts Institute of Technology
Research Project: GaN Schottky Diodes Leveraging High Workfunction Conductive Metal Oxides
Faculty Advisor: Prof. Ali Javey
Postdoc Mentor: Dr. Rehan Kapadia
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: N/type GaN was used to fabricate GaN/X, wProject poster X is a metal or metal oxide,
heterojunction diodes. Au, Ni, NiOx, and MoOx were the metals and metal oxides used in this study.
NiOx films were fabricated via thermal evaporation and then oxidized to change the film composition. The NiOx films were characterized via XPS and UV–VIS experiments.
The GaN/X devices showed a clear correspondence between p/type material workfunction and ON/OFF ratio. Furthermore, we show that MoOx, the highest workfunction material, results in the best ON/OFF ratio. This indicates that higher workfunction oxides are ideal candidates to use for Schottky diodes with n–type GaN.
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Undergraduate Researcher: Anthony Becerril
Major: Electrical Engineering
Home Institution: California State University, Long Beach
Research Project: Optimizing Thin Film Deposition for Terfenol-D Composition on a Silicon Substrate
Faculty Advisor: Prof. Jeffrey Bokor
Postdoc Mentor: Dr. Mark Nowakowski
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: With optimal sputtering deposition, Terfenol-D, a magnetostrictive material, and lead zirconate titanate (PZT), a piezoelectric material,
can form an energy-efficient, strain-coupled magnetoelectric device. The first step to achieving this is by thin film sputtering deposition of Terfenol-D onto Silicon.
Optimizing sputtering parameters will efficiently deposit Terfenol-D, retaining its original composition and magnetic properties. Composition is verified using
Electron Dispersive Spectroscopy (EDS) on a Scanning Electron Microscope (SEM).
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Undergraduate Researcher: Chanell Boyd
Major: Chemistry
Home Institution: Howard University
Faculty Advisor: Prof. Timothy M. Swager
Graduate Student Mentor: John Goods
Hosting Organization: Department of Chemistry, MIT
Undergraduate Researcher: Rene Brito
Major: Electrical Engineering
Home Institution: The University of Texas at El Paso
Research Project: Energy Analysis of Negative Capacitance
Faculty Advisor: Prof. Elad Alon
Graduate Student Mentor: Yue Lu
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: This project evaluates the potential energy costs of using a negative capacitance to reduce input capacitance of an optical receiver.
A circuit model for generating negative capacitance is analyzed, using small signal analysis, to determine the power consumption associated with each model.
The power consumption is compared with the improvement to optimum photon charge needed for the best energy efficiency of the circuit.
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Undergraduate Researcher: Neil Cammardella
Major: Electrical Engineering
Home Institution: University of South Florida
Research Project: Stress Gradient Analysis of Nano-Electro-Mechanical Relays
Faculty Advisor: Prof. Tsu-Jae King Liu
Postdoc Mentor: Dr. Louis Hutin
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: Nanoelectromechanical systems (NEMS) are being investigated as energy efficient alternatives to
CMOS logic switches. The air gap between source and drain electrodes in the off state prevents leakage currents and mechanical
operation makes possible a near-zero subthreshold swing. This project addresses the stress gradient in the moveable gate that
leads to undesirable out-of-plane bending. NEM relay devices were modeled using Coventor MEMS+ and simulated to sweep
design variables and assess their effect on out-of-plane bending and pull-in voltage.
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Undergraduate Researcher: Jorge Catalán
Major: Metallurgical and Materials Engineering
Home Institution: The University of Texas at El Paso
Research Project: Metal Oxide RRAM-based Artificial Synapse for Neuromorphic Computing System
Faculty Advisor: Prof. Tsu-Jae King Liu
Postdoc Mentor: Dr. Nuo Xu
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: Due to the synaptic features, (i.e. the gradual resistance value change versus applied bias magnitude or pulse width)
metal Oxide RRAM can be used as the building blocks of a neuromorphic computing network. By implementing the RRAM devices the visual
recognition and image processing performance of computers can be enhanced, yet, with largely reduced power consumption.
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Undergraduate Researcher: Jordan Goldstein
Major: Physics & Electrical Engineering
Home Institution: Massachusetts Institute of Technology
Research Project: InP-TiO2 Interfaces in NanoLEDs
Faculty Advisor: Prof. Ming C. Wu
Mentors: Michael Eggleston & Seth Fortuna
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: Optical antennae have shown promise in increasing the spontaneous emission rate (Rsp) of dyes and nanoscale semiconductor structures.
Project poster, we present time-resolved and time-averaged measurements of the fluorescence of InP thin films with and without a TiO2 coating. Using our results,
we calculate a surface recombination velocity of 13000 cm/s between InP and TiO2, and predict that a 300x Rsp speedup would be required to produce a
10 x 10 x 100 nm InP nanowire emitter with a quantum efficiency of 50%.
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Undergraduate Researcher: Matthew Hartley
Major: Electrical Engineering
Home Institution: University of Louisiana at Lafayette
Research Project: Investigation of Germanium-based Bipolar Junction Phototransistors
Faculty Advisor: Prof. Eli Yablonovitch
Graduate Student Mentor: Christopher Keraly
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: Replacing the electrical wires between transistors with optical interconnects can potentially lower energy consumption in chips.
A high gain, low capacitance optical detector is needed to drive the transistors in this optical system. Germanium bipolar phototransistors are a
promising candidate for these highly sensitive detectors in the infrared region. We are performing a 2D simulation of a purely germanium phototransistor
using the Sentaurus TCAD software from Synopsis. Using the Poisson/Drift-Diffusion solver built into the program, we modeled the optical and electrical behavior of the device.
The simulated results will help us design the phototransistor and understand how the device operates. A good match between the computer-generated results and the physical ones
will provide valuable insight into the design parameters. The results will pave the way towards smaller and more complex germanium-based phototransistors that
will meet the necessary requirements to be integrated into an optical interconnect system.
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Undergraduate Researcher: Satcher Hsieh
Major: Physics & Electrical Engineering
Home Institution: Washington University at St. Louis
Research Project: Modification of a Scanning Tunneling Microscope for Measurement of Ballistic Electron Emission Microscopy
Faculty Advisor: Prof. Jeffrey Bokor
Postdoc Mentor: Dr. Jeongmin Hong
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: Ballistic electron emission microscopy (BEEM) is a spatially resolved metrological tool most commonly used for subsurface
interface structures at the nanometer scale. We modify a scanning tunneling microscope (STM) to perform BEEM measurement via design and fabrication
of a novel sample stage. Furthermore, we design and fabricate an external magnetic field source that encapsulates the sample stage, setting the
foundation for future measurement of ballistic electron magnetic microscopy (BEMM). Instrumentation of the device and characterization of a sample with an ohmic interface,
Ni-Si, are implemented and discussed.
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Undergraduate Researcher: Janice Lin
Major: Chemistry
Home Institution: University of Maryland, College Park
Research Project: Growing Molybdenum Disulfide Monolayers by Sublimation
Faculty Advisor: Prof. Ali Javey
Postdoc Mentor: Dr. Rehan Kapadia
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: Transition metal dichalcogenides (TMDCs) are promising two-dimensional materials with properties
ideal for nanoelectronics and optoelectronics. TMDCs such as molybdenum disulfide (MoS2),
with a direct bandgap, can be used to fabricate devices with higher switching rates while simultaneously
scaling down transistors to the nanometer. Using closed space sublimation, we attempt to develop a controlled growth of
continuous films of one-atom thick molybdenum disulfide using direct evaporation of MoS2. The mechanism of growth of
these monolayers was observed as time, temperature, and pressure were changed for optimal growth.
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Undergraduate Researcher: Nathan Martin
Major: Materials Science and Engineering
Home Institution: University of Connecticut
|Faculty Advisor: Prof. Eugene A. Fitzgerald
Graduate Student Mentor: Ryan Iutzi
Hosting Organization: Department of Materials Science and Engineering, MIT
Undergraduate Researcher: Chelsea McConnell
Major: Chemical Engineering
Home Institution: Oregon State University
Faculty Advisor: Prof. Timothy M. Swager
Post Doc Student Mentor: Dr. Ellen Sletten
Hosting Organization: Department of Chemistry, MIT
Undergraduate Researcher: Joeson Wong
Major: Electrical Engineering
Home Institution: University of Michigan
Research Project: Achieving Global Optimization of Sub-Wavelength Thick Solar Cell Surface Texturing through Inverse Design
Faculty Advisor: Prof. Eli Yablonovitch
Graduate Student Mentors: Vidya Ganapati & Chi-Sing Ho
Hosting Organization: Electrical Engineering and Computer Sciences Department, UC Berkeley
Project Abstract: The Yablonovitch group has created a computationally efficient inverse design algorithm that maximizes a figure of merit, F(E, H, ω),
through successive iterations in the geometries of a system subject to the constraints of Maxwell’s equations. However, it appears that the final solution
computed by the inverse design algorithm may converge to a different local maxima for different initial conditions in the geometry. The surface texture of a
sub-wavelength solar cell presents an interesting system to test the inverse design algorithm more concretely. The surface texture is represented by a
truncated Fourier series, wProject poster the degrees of freedom is reduced to 2 in order to do a parameter sweep of the Fourier coefficients. A broad range of optima is found.
In addition, it appears that the location of the global optima occurs near punchthrough. Lastly, we find that MATLAB’s fminimax optimization converged to a
local maxima for a particular initial condition, showing that it is a local optimization routine. Thus, in order to achieve the global optimum,
a new optimization routine must be developed. Project poster
Undergraduate Researcher: Victoria Xu
Major: Physics
Home Institution: University of California, Santa Barbara
Research Project: Microwave Directional Coupler for Quantum Measurement
Faculty Advisor: Prof. Irfan Siddiqi
Graduate Student Mentor: Chris Macklin
Hosting Organization: Department of Physics, UC Berkeley
Project Abstract: We present the design, analysis, and measured S-Parameters of a 20 dB microwave directional coupler. The design parameters
were chosen to couple energy from a strong drive tone towards a parametric amplifier, which will
amplify the small signal containing the quantum mechanical information. With this application motivating
our design work, we show the results of our efforts to engineer a directional coupler in grounded coplanar waveguide
geometry. Current work is underway for on-chip integration of the successful design engineered from this
endeavor.
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