The 2024 M-SHORE REU projects will address key societal needs that can be met by semiconductor materials and device innovation such as: photocatalysis for solar fuels and carbon sequestration needed to mitigate the effects of climate change; new materials and integration methods to achieve nanoscale control of electronic properties for the next generation of computational circuits and high-resolution sensors; and innovation in photonics circuits and efficient power conversion devices to reduce global energy consumption.
Thrust Area: Wide Bandgap Materials and Devices
Project 1. Synthesis and photocatalytic properties of GaN nanostructures for sustainable energy devices (Prof. Zetian Mi, Electrical Engineering and Computer Science)
Artificial photosynthesis, i.e. the chemical transformation of sunlight, water, and carbon dioxide into high energy-rich fuels, is one of the keys to a sustainable, carbon-free, storable, and renewable source of energy. Although significant progress has been made for decades, the development of low cost, efficient, long-term stable semiconductor photocatalysts and photoelectrodes has remained challenging for the large-scale practical application of this frontier technology. The goal of this project is to investigate the optical, electronic, and photocatalytic properties of group III-nitride semiconductor nanostructures for artificial photosynthesis. These studies will help pave the way for the low cost, distributed generation of clean chemicals and fuels utilizing two of the most abundant natural resources on earth – sunlight and water – while significantly reducing carbon dioxide emissions. The REU student will study the structural and optical characterization of these nanostructures using scanning electron microscopy, photoluminescence spectroscopy, and photocatalytic water splitting experiments. The experimental results will be analyzed and correlated with the epitaxial growth and photocatalytic experiments. Over the past decade, Mi’s group has developed some of the most efficient artificial photosynthesis systems capable of direct solar water splitting and hydrogen fuel production. With support of Mi’s team and the LNF staff, an REU student will be able to make significant contributions to this technologically important research field.
Project 2. Enhancing p-type Doping of GaN for Power Electronics (Prof. Rachel Goldman, Materials Science and Engineering)
Si-based electronics are limited in high power applications by a low breakdown voltage. Wide bandgap semiconductors, such as gallium nitride, can support larger electric fields and thus higher voltages, with lower conduction loss. However, construction of bipolar semiconductor devices requires effective p– and n-type doping, and GaN p-type doping at high concentrations remains elusive. This project seeks to address this key knowledge gap. Goldman’s lab uses molecular beam epitaxy (MBE) to grow GaN. While surfactants and co-dopants such as O and Si used in MBE can improve p-type doping, the concentration of substitutional Mg is often limited, leading to limited p-type doping efficiency. The REU student will contribute to a larger project in Goldman’s group that is developing novel approaches to enhance the p-type doping of GaN and related alloys. The project involves a combined computational-experimental approach consisting of focused-ion-beam (FIB) nano-implantation of Mg in GaN during MBE, followed by computational and experimental ion channeling studies of Mg incorporation. The REU student will participate in the development of a modified Mg-Ga alloy source for FIB nano-implantation. They will perform hands-on analysis, assembly and test of the source, and will learn to analyze the epitaxy results to assess success. For example, the student will have the chance to assist in performing ion channeling measurements of doping and point defects in GaN and related alloys, to determine the impact of the new Mg-Ga alloy source on p-type doping. Additionally, the REU student will be introduced to the methods of Monte Carlo-Molecular Dynamics simulations of doping and point defects in GaN and related alloys, which will be used to interpret and corroborate the experimental results. By working on a discrete part of a larger project, the REU student will make key contributions to the development of game-changing technologies for high power electronics.
Thrust Area: Complex Oxide Materials and Devices
Project 3. Thin film deposition of (MgCoNiCuZn)O based entropy-stabilized oxides with tunable conductivity (Prof. John Heron, Materials Science and Engineering)
Entropy-stabilized oxides are unique due to phase stability deriving from configurational disorder. The materialsdisplay exciting interplay between charge, structure, and spin derived from the underlying local disorder and leads to enhanced performance in ion transport, memristive behavior, and magnetic exchange bias. In this project, films of (MgCoNiCuZn)O and its compositional variants will be deposited on a variety of different substrates to investigate the roles of strain and chemistry on growth mode, structure, and transport characteristics. The student will get hands on thin film deposition experience and training in xray diffraction, atomic force microscopy, reflection high energy electron diffraction and quasi DC electrical characterization.
Project 4. Doping of germanium oxide semiconductors (Prof. Becky Peterson, Electrical Engineering and Computer Science)
Wide bandgap semiconductors such as GaN and SiC have been commercialized for diverse power electronics applications including power inverters in electrified vehicles and fast AC to DC charging. Current research explores ultra-wide bandgap (UWBG) semiconductors (~4.5eV+) to address even higher voltage, higher power future applications. Germanium dioxide, GeO2, has been theoretically predicted as a bi-polar dopable UWBG semiconductor. In this project, the REU student will work with a graduate student in Peterson’s group to use RF sputtering to deposit germanium dioxide films, pattern the layers, deposit metal contacts, and characterize the films electrical and material properties. The REU student will learn how to use numerous nanofabrication tools (no prior knowledge is assumed) and the project will contribute significantly to our fundamental understanding of UWBG materials for future high voltage and high power electronics.
Project 5. Solid-state electrochemical memory devices utilizing ions (Prof. Yiyang Li, Materials Science and Engineering)
Solid-state electronic devices function through the ability to control the motion of electrons and holes in solids. While these CMOS devices have been responsible to the exceptional performance of computers today, there are certain fundamental limitations of modern semiconductor technology. Solid-state ionic devices that utilize the motion of ions can overcome some of these limits by being analog, which is more efficient for artificial intelligence applications, and being more resilient to extreme environments like high temperatures, ionizing radiation, and electromagnetic interference. The Li+ group is developing solid-state devices that also utilize ions, particularly oxygen vacancies, to store and process information. Students will learn to fabricate and test these ionic memory devices, as well as characterize the materials that these devices utilize. This project is ideally suited to students with an interest in chemistry or materials science in addition to semiconductors.
Thrust Area: Nanotechnology for Devices
Project 6. Structural color based on aerogel & nanoparticles (Prof. L. Jay Guo, Electrical Engineering and Computer Science)
Localized surface plasmon resonance occurs from the interaction between light and metals nanoparticle and can be used to generate strong plasmonic colors. The oscillation of surface electrons resonate at a frequency affected by the optical properties of the medium. This project will explore one medium of particular interest, silicon dioxide (SiO2) aerogel, having a refractive index close to that of air. However, processing SiO2 aerogel at ambient pressures remains a challenge due to the brittle nature of the SiO2 framework. The REU student will be involved in our effort of developing a solution-processable, ambiently dried thin-film aerogel as a potential method for enhancing the plasmonic color of metal nanoparticles. Working on this project with the mentor will provide the student with opportunity to gain experience with solution processing methods such as spin coating and dip coating; metrological skills such as scanning electron microscopy and ellipsometry; wet chemistry skills for SiO2 aerogel and gold nanoparticle synthesis; and experience working in both a clean room facility and a wet chemistry laboratory.
Project 7. High-resolution temperature sensors and calorimetry (Prof. Pramod Reddy, Mechanical Engineering)
Energy dissipation and conversion play a central role in many devices. The design and fabrication of these energy conversion devices, as well as many fundamental scientific investigations, such as those in high-energy physics, requires high-resolution temperature and calorimetry sensing. In this project, the REU student will explore and understand the principles of high-resolution calorimetric and thermometry techniques that are central to quantifying energy conversion processes. Specifically, the REU student will participate in the nanofabrication of calorimetric scanning probes with integrated thermal sensors that enable measurements of temperature fields with single digit nanometer resolution. As part of this experience, with support of graduate student mentors, the REU student will employ calorimetric scanning probes to visualize heat dissipation in functional electronic devices with nanometer resolution and relate it to the band structure of the devices. Contributing to these studies will provide students with a more detailed understanding of the microscopic processes (e.g. electron-phonon interactions, phonon scattering at interfaces, Peltier cooling at interfaces, to name a few) that influence device performance and device characteristics. Further, these state-of-the-art experiments will provide critical information to help scientists design future devices with more efficient performance. Finally, the REU student will also learn the principles of ultra-sensitive electronic measurements and gain experience in bandwidth-narrowing techniques such as phase-lock loop detection that can be widely used in their future careers.
Project 8. Electrical Packaging for Silicon Nitride Quantum Chips (Prof. Zheshen Zhang, Electrical Engineering and Computer Science)
Silicon nitride photonic chips have demonstrated significant applications in the field of quantum information processing. The essential functionalities of system-level stabilization and modulation play a pivotal role in advancing Silicon Nitride quantum chips towards practical implementations in quantum technology. This project aims to develop advanced electrical packaging and control techniques, establishing interfaces between Silicon Nitride quantum chips and standard electrical components. These interfaces will be utilized for the stabilization and modulation of various photonic quantum components. The REU student engaged in this project will have the opportunity to acquire advanced nanofabrication skills, including photolithography, e-beam evaporation, lift-off processing, and wire bonding. Additionally, they will gain proficiency in testing Silicon Nitride quantum chips and developing control codes using programming languages such as Python and LabView. This research experience will provide a comprehensive understanding of state-of-the-art quantum technology and hands-on expertise in the fabrication and control of quantum components.
Project 9. Fabrication and Characterization of Large-Area Atomically Thin Semiconductors (Prof. Parag Deotare, Electrical Engineering and Computer Science)
The recent emergence of low dimensional quantum materials has provided an excellent platform to investigate various fundamental quantum excitations. In some materials such as monolayers of Transition Metal Dichalcogenides (TMDs), the Coulombic attraction between 2D electrons and holes binds to form hydrogen-like quasiparticles known as excitons. The strong binding energy in TMDs provide a unique platform for next-generation room temperature excitonic devices serving various applications from communication to sensing. The project will involve developing a new technique to create clean, and large-area TMD monolayers from bulk crystals. Traditional mechanical exfoliation techniques can leave polydimethylsiloxane (PDMS) residues on the TMD material surface, which significantly compromises the excitonic properties. The aim is to use noble metals such as gold for exfoliation that can utilize the chemical affinity of chalcogen atoms to create a stronger interaction between the TMD material and gold surface, thus enabling the exfoliation of clean two-dimensional TMD layers. Some of the fabrication tasks will include sample preparation, deposition of metal films under high vacuum, metrology of the film, etching and mechanical exfoliation. Characterization tasks may involve the use of SEM, AFM or optical spectroscopy.
Project 10. Fabrication and integration of memristor devices for event-camera integration (Prof. Wei Lu, Electrical Engineering and Computer Science)
Memristor devices are two-terminal electronic devices whose internal state reflects the input history. In prior studies we have used memristors with short-term memory effects to perform object classification, speech recognition, and time-series prediction. These devices allow on-sensor, real time processing of temporal signals such as those produced by event-based cameras. Combined with convolutional neural network (CNN) blocks that can process spatial information, the resulting network can be used to efficiently process tasks neuromorphic object classification, scene/object detection with high speed and ultra-low latency. The REU student will work with the PhD student mentor on the device fabrication, thin film growth, photolithography, deposition, as well as device characterization including DC and pulse testing. Device modeling and neural network implementation and characterization will also be performed.