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EE Research Opportunities

Research Opportunities in Electrical Engineering for Undergraduates

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Micro-fabricated Negative-index Metamaterial Lenses for Passive Near-horizon Beam-steering

chisum.jpgDescription: As the demand for mobile data continues to grow at exponential rates the wireless industry is looking toward the millimeter-wave regime (50-90 GHz) to access untapped spectrum (up to 20 GHz of contiguous spectrum) to meet this demand. One of the key challenges of millimeter-wave systems is the increased path loss (20log(f)) at high frequencies compared with current sub-6 GHz wireless networks. A proposed solution is to employ highgain antenna arrays which compensate for the path loss but have a corresponding narrow beamwidth. In order to maintain a wireless link with a mobile device beam-steering is employed. Traditional beam-steering uses active phased arrays which incur high cost and power dissipation. An alternative to active phased array beam-steering antennas is the passive Luneberg lens which boasts zero power dissipation, low-loss, and high gain. However, the Luneberg lens is a 3D (spherical) gradient index lens traditionally requiring elaborate machining of concentric shells of dielectric. Due to the difficulties of fabrication this lens has traditionally only been realized in bands below 20 GHz.

With such a structure we can vary the permittivity in a 2D plan (a wafer) and by stacking multiple wafers we can vary the permittivity throughout a 3D structure. So far our approach is able to achieve only “ordinary media” (εr>=1.0) which enforced certain limits on the maximum angle that a beam can be steered. In order to steer a beam to the horizon, permittivity must be allowed to exceed the ordinary limit. By integrating vertical metallization in the etched voids we can incorporate the so-called “thin-wire” metamaterial unit-cell into our structure and achieve εr<1.0 and even εr<0. This provides additional flexibility to achieve near-horizon beam-steering.

Working in NDnano’s state-of-the-art nanofabrication facility, and in conjunction with one or multiple graduate
students, the NURF student will perform design simulations, mask design, pattern generation, lithography,
etching, and measurement in support of three technical objectives for this project:

  1. In conjunction with the faculty advisor and graduate student mentor, develop the theory for the design of the negative permittivty unit cell
  2. Simulate the design in a full-wave electromagnetic solver (e.g., Ansys HFSS)
  3. Fabricate and measure the new negative (or reduced) permittivity unit cell in the clean

Not only will the work in this project complement ongoing research, it will provide an enabling technology for
many follow-on projects. A rising junior or senior with electrical engineering background is expected but qualified candidates from all levels will be considered. Given the nature of microfabrication tasks the undergraduate student will team with at least one graduate student to provide continuity and additional effort applied to the task.

Contact: Assistant Professor Jonathan Chisum, 226A Cushing Hall, (574) 631-3915 (jchisum@nd.edu)

Steep Slope Ferroelectric Transistors

datta imageTechnical Objectives: The recent experimental detection of negative differential capacitance in ferroelectric dielectrics [1] rekindles our hopes that the phenomenon can be harnessed to push transistor scaling and energy efficient nanoelectronics. The unstable negative capacitance of the ferroelectric has been predicted before [2, 3], but it’s direct measurement is elusive. However, one can stabilize the negative capacitance of ferroelectric by putting it in series with the positive channel capacitance of the transistor. Recently, in our group, we have develop a novel ferroelectric dielectric that is integrated directly within the gate stack of a Silicon transistor to form a ferroelectric field effect transistor. In this proposed REU project, the researchers will have an opportunity to characterize the Ferro FETs in detail and participate in developing device physics based simulation models of the resulting Ferro FETs.

Preferred Background: The REU student should have taken an undergraduate course in Semiconductor Device Physics or equivalent. Preference will be given to students who have some experience in electrical characterization of transistors, diodes, capacitors, inductors etc.

References
[1] Khan, A. I. et al. Nature Mater. 14, 182–186 (2015)
[2] Bratkovsky, A. M. & Levanyuk, A. P. Phys. Rev. B 63, 132103 (2001)
[3] Ershov, M. et al. IEEE Trans. Electron. Dev. 45, 2196–2206 (1998)

Contact: Professor Suman Datta, 271 Fitzpatrick Hall, 574 631-8835 (sdatta@nd.edu)
Department of Electrical Engineering

Phononic Nanoparticles for Low-Loss, Tunable Nanophotonics in the Mid- and Far-IR

hoffman imageTechnical Objectives: Phononic nanoparticles are a new class of optical materials with untapped potential for
realizing new mid- and far-infrared detection and sensing nanotechnologies that are functionally analogous to ultraviolet and near-infrared plasmonic nanotechnologies but with even greater sensitivity. Phononic nanotechnologies have potential application in analytical chemistry, biomedicine, environmental science, homeland security, astrophysics, and geology. However, basic scientific knowledge of the governing structure-property relationships for engineering the optical properties of phononic nanoparticles are not well understood or developed. Therefore, students on this project will investigate the optical properties of candidate phononic materials using both modeling and experimental characterization of synthesized nanoparticles. As such, this interdisciplinary research experience will cut across both materials science and optical science.

Contacts: Professor Anthony Hoffman, 226B Cushing Hall, 574 631-4103 (ajhoffman@nd.edu)
Department of Electrical Engineering

Professor Ryan K. Roeder, 148 Multidisciplinary Research Building, 574 631-7003 (rroeder@nd.edu
)
Department of Aerospace and Mechanical Engineering

Noise Measurements in Nanoscale Single-Electron Devices

orlov imageDescription: Single electron tunneling transistors (SET) are quantum mechanical devices that are capable of detecting a tiny displacement of charge (much less than one electron!) in a nearby nanostructure coupled to it. But this unique capability of SET sensing device is limited by noise. Noise is a fascinating phenomenon where physical system exhibits random fluctuation of its parameters which in case of sensors like SET ultimately limits its ability to act as a detector. By carefully designing parameters of the SETs one can improve their immunity to by orders of magnitude. But what are the underlying physical mechanism that lead to a drastic differences in performance, like shown in the figure below? Projects in the group of Professor Alexei Orlov study the connections between SET fabrication steps and resulting device performance and explore the limits imposed by various sources of noise on the performance of the SET devices. The projects will include building circuits (amplifiers and filters) for noise measurements at different temperatures (from room temperature, 300K down to a very low, 0.3K) as well as the actual measurements of SETs and data analysis. A student involved in these projects will gain experience in hardware design and implementations, device measurement and
data analysis techniques, and some programming.

Student Involvement: Students will work on the experimental measurements, data analysis, construction of circuits, and writing control programs.

Preferred Disciplines: Physics, Electrical Engineering, and Computer Science students are preferred. Some knowledge of programming, data analysis and soldering is helpful.

Contacts: Research Professor Alexei Orlov, 227 Stinson Remick Hall, 574 631-8079 (aorlov@nd.edu)
Department of Electrical Engineering

Automated Testing of Tunnel Field-effect Transistors

Description: The student will work with graduate students and post docs to advance the development of
tunnel field effect transistors (TFET). These transistors are more energy efficient than the Si MOSFET. The student will use a Cascade autoprober which allows step and repeat probing of devices on chip, and learn an integrated measurement software called Wavevue for control and analysis of the data. The goal of the project is to develop automated measurement routines and methods to extract key performance measures for the transistors, and then generate automated reports that students can use to document progress.

The expected and/or anticipated involvement of the REU student in the research. The student will learn transistor testing, measurement automation, and data analysis to understand the physics of TFETs.

Preferred discipline(s), expertise, lab skills, etc. Ability to learn software, an interest in semiconductor devices, an interest in automated currentvoltage and capacitance-voltage testing, ability to solve problems
Optional information such as limitations on schedule, preferred universities, etc. none

Contacts: Professor Alan Seabaugh, 230A Cushing Hall, 574 631-4473 (aseabaug@nd.edu)
Department of Electrical Engineering

Energy Recovery for Ultra-low Energy Computation

snider imageDescription: Anyone who owns a laptop knows that power dissipation and the associated heat are a problem for the microelectronics industry. As electronic devices scale down in size, they use less power (and hence energy), but is there a lower limit to the energy that must be dissipated by each device? Recent experimental measurements have demonstrated our ability to measure energy dissipation in the range of a ~15 yJ (1 yJ is
10-24 J), and we are building CMOS circuits to operate in this range. Projects in the group of Professor Gregory Snider will explore the limits of ultra-low power computing, and designing, building and measuring circuits that test these limits, and clock circuits that can recycle the energy used in computation. The projects will include building circuits and amplifiers for energy measurements of the CMOS circuits as well as the actual measurements. The project will also include the design of the next generation of the adiabatic circuits. A student involved in these projects will gain experience in programming, CMOS design, and device measurement techniques.

Student Involvement: Students will work on the construction of circuits, writing control programs, and making measurements.

Preferred Disciplines: Electrical Engineering, Physics, and Computer Science students are preferred. Some knowledge of programming and soldering is helpful.

Contacts: Professor Gregory Snider, 275 Fitzpatrick Hall, 574 631-4148 (gsnider@nd.edu)
Department of Electrical Engineering