Summer Research Projects in 2008:
Silicon based Nanoelectronics:
Title Characterization of novel silicon nanoelectronic devices Faculty Professor Sandip Tiwari (email) Dept. Electrical and Computer Engineering (group website) Project The student will perform measurements on a new type of complementary metal-oxide semiconductor field-effect transistor where a thin film of single crystal silicon has a gate on either side of the structure. This allows the threshold voltage of the device to be varied. It also allows the structure to operate as a memory when one of the gates is floating. Such devices have been fabricated in Cornell Nanoscale Facility and the student will write programs for time-domain, frequency-domain and static characterization, use these programs for characterization, and may do additional simulation and modeling in support of understanding the behavior of devices.
Title Characterization of Circuit Design Techniques for Reduced Process Variation Faculty Professor Alyssa Apsel (email) Dept. Electrical and Computer Engineering (group website) Project As feature sizes of microelectronic devices decrease into the nanometer regime, variations in device and circuit characteristics such as threshold voltage, current, transconductance, and output resistance make the design of matched, high yield circuits and systems increasingly difficult. By developing circuit design techniques that consider both the deterministic behavior of devices as well as their stochastic variations across process, designers can begin to reduce the impact of these variations on circuit yield. In our lab, we have developed a basic design methodology to enable such reduced variation design and are in the process of designing a class of circuits for this purpose. An undergraduate working on this project will experimentally measure device and circuit variations in scaled CMOS processes and use these results to both characterize the process and the improvements to the process due to the circuit design.
Title Flash Memory Device Optimization for Nonvolatile Computing Faculty Professor Edwin Kan (email) Dept. Electrical and Computer Engineering (group website) Project With the design variations in CMOS flash memory cells, nonvolatile computing can become realistic and even competitive for small systems operating on unstable power supply. Nonvolatile computing is defined as computing and communication that can restart correctly for any power supply interruption. The first step is to use flash memory cells in all pipeline and cache storage, and then the circuits will need to be delay insensitive. The project can work in two aspects: 1) measurement of low-voltage flash cells; 2) construction of SPICE models for circuit evaluation; 3) benchmark in small computing modules. Carbon based Nanoelectronics:
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Title Fabrication of Organic Electronic Devices Faculty Professor George G. Malliaras (email) Dept. Materials Science and Engineering (group website) Project The student will work with a graduate student on the fabrication of circuits from organic thin film transistors (OTFTs) and light emitting diodes (OLEDs) . He/she will learn how to deposit organic semiconductors, pattern them using a novel approach developed at Cornell, and study the performance of these devices. Background in Materials Science or Physics is required.
Title Growth and measurement of carbon nanotubes Faculty Professor Paul McEuen (email) Dept. Physics (group website) Project Nanometer-diameter cylinders of graphite, known as carbon nanotubes, are an exciting new class of nanoscale materials with remarkable physical and electronic properties. In this project, you will grow these nanotubes and subsequently measure their properties using electrical measurements and scanned probe microscopy. Scanned probe microscopy uses a tiny tip on the end of a cantilever to measure the characteristics of samples at the atomic or near-atomic scale. The tip will be used to perturb the local conducting properties of the tube or to measure the local voltage inside the tube. Experience will be gained in scanned probe microscopy, nanoelectronic devices, and materials growth.
Nanomagnetics:
Title Manipulating Nanomagnets with Spin-Polarized Currents Faculty Professor Daniel C. Ralph (email) Dept. Physics (group website) Project In the last five years, a new mechanism has been discovered to manipulate the orientation of the north and south poles of a small magnet, without using an applied magnetic field. Instead, a torque can be applied to the magnetic moment by a direct transfer of spin angular momentum from a spin-polarized current. This effect may have important applications, for instance, in making ultra-dense magnetic memories. Our group is conducting experiments to understand the microscopic mechanism behind this torque and the ways in which a magnet can move in response to the torque. The summer project would involve techniques related to the fabrication of nanometer-scale magnetic devices, high-speed measurements of magnetic dynamics, and possibly computer modeling to compare the results of theoretical models to the experimental data
Title Spin-dependent Transport Through Tunnel Barriers Faculty Professor Piet Brouwer (email) Dept. Physics (group website) Project This project is closely related to "Manipulating Nanomagnetswith Spin-Polarized Currents" (Prof. Ralph). It addresses the dynamicsof a thin nanomagnet in a magnetic multilayer, under the influence ofan electrical current. The current exerts a torque on the nanomagnetvia a mechanism known as "spin transfer". The spin transfer torque canbe large enough to reverse the magnet's magnetizationdirection. Theoretically, the spin transfer torque is well understoodfor multilayers in which the magnetic layers are separated by normalmetals. For practical applications, separation by tunnel barriers ismore relevant, however. The goal of this project is to improve thetheoretical understanding of the spin transfer torque between two ferromagnets separated by a tunnel barrier.
Title Magnetic Materials at the Nanoscale: Studying and Developing New Spintronic Devices for High Performance Information Technologies Faculty Professor Robert Buhrman (email) Dept. Applied & Engineering Physics (group website) Project The strong spin-dependent electron transport properties of thin film magnetic multilayer systems offer the prospect of new types of high performance magnetic memory devices, sensors and other types of new nanoscale spintronic devices for signal processing whose functionality depends on the spin of the electron as well as its charge. To understand the physics underlying these properties and to develop them for possible applications will require extensive efforts to manipulate and characterize the properties of magnetic materials with nanoscale dimensions. This project will be concerned with using sophisticated thin film techniques to produce ultra-thin multilayer films with desired magnetic properties and with characterizing these materials by state-of-the-art tools and through extensive electronic transport measurements. Nanophotonics:
Title Quantum confinement of electrons in lead-salt nanocrystals Faculty Professor Frank W. Wise (email) Dept. Applied and Engineering Physics (group website) Project In lead-salt (PbS, PbSe, PbTe) nanocrystals, electrons are squeezed into a much smaller volume than they would occupy in nature. This drastically alters the electronic energy levels, and therefore the electronic and optical properties of the material. For example, the color of the material can be changed from black to red by changing only the size of the nanocrystal, not its composition. We study the fundamental physics of these nanocrystals, and also assess their potential utility as materials that could be used as light emitters in future optical integrated circuits. An undergraduate working on this project will learn how to synthesize semiconductor nanocrystals, use optical techniques and instrumentation to determine their electronic states and optical properties.
Title Light Propagation in Photonic Crystal Fibers Faculty Professor Alexander Gaeta (email) Dept. Applied & Engineering Physics (group website) Project Photonic crystal fibers are optical waveguides with cross-sections consisting of a periodic air-glass lattices. Such fibers can have exotic optical properties such as extended guidance of light in a gas or in a sub-wavelength region which allows for light-matter interactions not possible with any other system. The student on this project will investigate various properties of photonic crystal fibers including the propagation of high-power femtosecond laser pulses through these waveguides.
Title Optical modulator on-chip Faculty Professor Michal Lipson (email) Dept. Electrical and Computer Engineering (group website) Project The student will work on the design, fabrication and characterization of compact ring resonator based optical modulators and switches. He/she will learn how to setup chip-level optical waveguide experiments and learn the basics of fabricating monolithic optoelectronic integrated circuits (OEICs). The student is expected to know basic optical physics.
Nanocharacterization and Nanoprocessing:
Title Rare-earth (Eu or Er) Doped GaN Nanoparticles for Applications in Waveguides or LEDs Faculty Professor Michael Spencer (email) Dept. Electrical and Computer Engineering (group website) Project Wide bandgap semiconductor GaN is an efficient and robust host for rare earth-based photoemission at visible or infrared wavelengths. For example, Eu and Er doped GaN powders have been fabricated in our lab which have red and green luminescence respectively. We have shown recently that the rare-earth doped GaN powders (nanoparticles) can be deposited by a solution method which allows a high coverage of the substrate and thus is promising for applications in solid-state lighting devices. The student will have an opportunity to work from the materials preparation to device fabrication and thus have a good understanding of both.
Title Organic Transistors Faculty Professor John A. Marohn (email) Dept. Chemistry and Chemical Biology (group website) Project This project is a part of an ongoing effort to study charge motion in organic semiconducting films. Transistors will be prepared using different organic molecules, and using different surface treatments. The molecules will be deposited onto the transistor substrates by either spin casting or vacuum evaporation. The electrical characteristics of the organic transistors will be analyzed to uncover evidence of charge trapping and to quantify charge mobility. If time permits, the REU will collaborate with a graduate student to analyze an organic transistor by electric force microscopy.
Title Study of Quantum Structures with Atomic Resolution Electron Microscopy and Spectroscopy Faculty Prof. David Muller (email) and (group website) and Prof John Silcox (email) and (group website) Dept. Applied and Engineering Physics Project Explore the physical and electronic structure of natural and engineered nanostructures using an atomic-resolution electron microscope. Projects can range from instrument design and construction to the investigation of new nanomaterials, depending on the students interests.
Title Chemical Control of Nanomechanical Strength Faculty Prof. Melissa Hines (email) and (group website) Dept. Chemistry and Chemical Biology Project If someone told you they had a wax that would make your car stronger and more resistant to dents and dings, would you buy it? Probably not, as common sense tells you that a layer of wax won't have any affect on a steel panel. Unfortunately, common sense doesn't work at the nanoscale, and we have recently shown that a single molecular layer of "wax" can improve the strength of nanomechanical silicon beams. What is the origin of this unusual chemical effect? Can we increase the strength even further, perhaps reaching the theoretically predicted strength, which is only limited by the Si-Si bond strength? In this project, a summer student will work with an interactive and interdisciplinary group to to study the effects of surface chemistry on nanomechanical strength. The student will use synthetic chemistry to functionalize nanoscale silicon beams, infrared spectroscopy to analyze the chemical state of the surface, atomic force microscopy to test materials strength, and computational analysis to extract fracture strengths. The student will work in a team environment with another undergraduate student and a graduate student or two. Prior experience in chemistry and chemical safety is desirable.
