Electronic Materials
Materials and processing for enabling microelectronic, optical, and electromechanical systems
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Nanomaterials (Graphene Nano-Platelets) as Multifunctional Modifiers for Polymers
Much excitement has been generated in recent times with the new research focus on materials and processes at the nanoscale. Polymers containing nanoscale additives and reinforcements (e.g. carbon nanotubes, nanoclays) have been shown to possess new, unique physical and chemical properties allowing them to be utilized in new applications such as interior and exterior accessories for automobiles, structural components for portable electronic devices and films. While a great deal of nanolevel research has focused on exfoliated clay platelets and carbon nanotubes, a natural nanostructured mineral, graphite, is known to consist of layers of carbon atoms (graphene sheets) assembled into a layered material. Graphite is one of the stiffest materials found abundantly in nature, and has excellent mechanical, electrical, thermal, lubrication and barrier properties.
This research project is directed at understanding the properties and processes of exfoliated graphite in order to create a new multifunctional additive for polymers. Research completed in the Drzal Group has already shown that with the appropriate surface treatment, graphene sheets can be exfoliated and dispersed in thermoset or thermoplastic polymers resulting in polymers with excellent stiffness, strength, toughness, electrical conductivity, thermal conductivity, and low coefficient of thermal expansion, electromagnetic shielding properties and high barrier properties as well. Current research is directed at the processing and properties of high performance polymers modified with multifunctional exfoliated graphite nanoplatelets for high capacity battery, high performance fuel cell and membrane applications.
Investigators (PI is linked): Lawrence T. Drzal
Categories: Nanomaterials, Electronic Materials
Optimal Microstructural Design Engineering of Diamond Films
Surface morphology and crystallographic texture is characterized for a set of diamond films that were deposited with different partial pressures of nitrogen and with different times of deposition. Textures varied from 110 type fiber texture for low nitrogen, and changed systematically to 100 type fiber texture with increasing nitrogen. The effect of deposition parameters on these physical conditions and the impact they have on mechanical properties is under investigation. Collaboration with V.M. Ayres, ECE Dept.
Investigators (PI is linked): Thomas R. Bieler
Categories: Electronic Materials
Nanostructured Bulk Thermoelectric Materials and Devices
Under support from the Office of Naval Research (ONR), we are developing lead telluride based thermoelectric materials into devices for electrical power generation from waste heat sources. The team includes researchers from Michigan State University (Hogan, Case, Schock, Mahanti), Northwestern University (Kanatzidis), and the University of Michigan (Uher).
Investigators (PI is linked): Tim Hogan
Categories: Electronic Materials, Energy Production
Lead-Free Electronic Solders for Severe Service Conditions
Electronic solder joints present in modern microelectronics encounter several severe simultaneous fields during service. Severe fluctuations in temperatures causing thermomechanical fatigue, high current density causing electromigration, and mechanical stresses, encountered during service significantly affect the reliability of the electronic interconnects. In addition to their individual influences, synergistic interactions between them play significant roles. In tin based electronics, whisker growth and tin-pest resulting from phase transformation are also becoming long-term reliability concerns. Current focus of the project is to develop a fundamental understanding of these issues by carrying out detailed studies on microstructural evolution and its influence on the life of the electronic solder joints. The main aim of the project is to develop suitable models for reliability predictions, and arrive at appropriate solutions to combat such problems.
Investigators (PI is linked): K.N. Subramanian
Categories: Electronic Materials, Advanced Metallic Systems
Microstructural Evolution from Ageing, Creep and Thermomechanical Fatigue in Lead Free Solders
Characterization and modeling of microstructural evolution due to thermomechanical fatigue in solder joints is investigated using several approaches. Currently we are using specially designed joints to facilitate observation and interrogation of the microstructure using scanning electron microscopy, orientation imaging microscopy (to map crystal orientations along with microstructure features) and nanoindentation. Recent reserach projects have included investigations into residual stress, stress relaxation, localized deformation during creep, and effects of reinforcements in composite solders manufactured by ex-situ and in-situ methods. This project is supported by a focused research group (Subramanian, Bieler, Lucas) grant from NSF (NSF-DMR-0081796), Visteon, and the Michigan State University Composite Materials and Research Center Current students: Honjoo Rhee (nano-indentation), Jong-Gi Lee (thermomechanical fatigue specimens), Adwait Telang (orientation imaging, reversed shear), Hairong Jaing (new) Students recently graduated: Sunlak Choi, Ph.D. (in-situ composite solder) Fu Guo, Ph.D. (ex-situ composite solder), Susheel Jadhav, M.S. (Stress-relaxation), Jeff McDougall (localized creep deformation)
Investigators (PI is linked): Thomas R. Bieler
Categories: Advanced Metallic Systems, Structural Materials, Electronic Materials
Engineering Surfaces and Interfaces
Self-assembly, microcontact printing, and layer-by-layer assembly techniques for surface tuning and patterning are utilized to develop new opto-electronic and bio applications. A variety of materials, such as organic and inorganic molecules, polymers, particles, and biomolecules including cells are used to prepare topologically and functionally structured surfaces for their desired purposes using novel self and directed assembly techniques.
Investigators (PI is linked): Ilsoon Lee
http://www.egr.msu.edu/~leeil/ilsoon_research.html#Ilsoon%20Lee%
Categories: Nanomaterials, Biomaterials, Electronic Materials, Polymer Composites, Structural Materials, Polymer Science and Engineering, Colloid and Interface Science, Biotechnology
Development of Nanostructured Lead-free Solder
In order to improve the service performance of lead-free electronic solders a sub-micron size inert and stable reinforcement, that bonds extremely well and be present in grain boundary regions of the solder matrix without any agglomeration during processing or coarsening during additional exposure to service environments, is essential. Unluckily, traditionally evaluated approaches utilizing ceramic, metallic and IMC particulate reinforcements or alloying methodologies do not satisfy all these requirements. POSS-silanols containing one to three (Si-OH) groups consist of inert strongly bonded cage structure made of Si-O with surface active groups. As a consequence, the negatively charged -OH surface active groups present in POSS may strongly bond with the metallic matrix, hopefully to the grain boundary regions of the solder. The negatively charged surface active groups present on the surface of POSS should also prevent flocculation of these reinforcements during processing. Since bonding between Si and O is very strong, they will not dissociate in service environments. This will alleviate any coarsening problems that may be encountered during service.
Investigators (PI is linked): Andre Y. Lee
Categories: Nanomaterials, Electronic Materials, Advanced Metallic Systems
Radiation Effects on the Structure and Electronic Properties of Carbon Nanotubes
Traditional Si based electrons are susceptible to rapid degradation in space radiation environments, limiting their application in satellite and space exploration systems. Currently, carbon nanotubes are being developed for nanoscale electronic circuits. In this program, we are studying the stability of carbon nanotubes and nanotubes/metal contacts when exposed to high energy radiation. These structures are being irradiated with high energy (12,000 MeV) 86Kr ions, which simulate space radiation environments, in the National Superconducting Cyclotron Laboratory at Michigan State University. The irradiated structures are being characterized using high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) in order to determine the structural and electronic degradation as a function of exposure.
Investigators (PI is linked): Martin A. Crimp
Categories: Advanced Metallic Systems, Electronic Materials
Growth and Characterization of Rare-Earth Silicide Nanowires and Nanostructures
Self-assembled nanowires are potential structures for interconnects in nanoscale electronic applications. In this study, GdSi2, DySi2, and ScDy2 nanostructures are being grown on Si(100) substrates by evaporation/self assembly. Bulk coverages ranging from 0.3 to 3.0 monolayers of silicide result in a variety of morphologies and crystal structures. Large aspect ratio nanowires grow have been found to grow in <110>Si directions. Larger rectangular 3-D islands are also observed. The relationships between substrates, growth conditions, and nanostructure morphology and crystal structure are being characterized using scanning tunneling microscopy and advanced transmission electron microscopy techniques including HRTEM, convergent beam electron diffraction, and EELS.
Investigators (PI is linked): Martin A. Crimp
Categories: Advanced Metallic Systems, Electronic Materials
New Materials for Thermoelectric Energy Conversion
A critically important and developing area in materials science is the discovery of new thermoelectric materials with enhanced efficiency. These materials are capable of converting heat (such as that from an active source like the sun, or waste heat from an industrial process) to electricity; their use can offer an increase in energy efficiency for industrial processes as well as provide additional sources of useful electrical energy. Current research is focused on filled skutterudite compounds, unusual intermetallic semiconductors, and nanoscale lead telluride-based thermoelectrics.
Investigators (PI is linked): Donald Morelli
Categories: Electronic Materials