Vishwanath Prasad - US grants

A six-month program is planned for the summer faculty internship award in tribology. The major objective of the training/research program is to acquire in-depth knowledge of the experimental and computational research in tribology, particularly in the areas of fluid inertia and viscoelasticity, thermal effects, such as instability and property variation, thermal interaction between the fluid film and surrounding environment, and high-resolution computational techniques. The Institute for Wear Control and Tribology at Rensselaer Polytechnic Institute will act as the host institution for the training and research. A long-term computational and experimental research strategy will be developed for complex thermohydrodynamic problems of greater concern and immediate attention.

Research is in the area of materials engineering and manufacturing processes aimed at acquiring in-depth knowledge of basic physical phenomena in Czochralski (CZ) crystal growth equipment processes, major scientific and engineering considerations in computer-aided design and manufacturing of an automated "one button control" puller, cost consideration, and United States competitiveness in world market for CZ crystal puller. Preliminary research will be performed on continuously-charged Czochralski (CCZ) growth of silicon single crystals. The CCZ process is expected to produce crystals of uniform properties, better quality and lesser costs. The research on CCZ process will include theoretical work in order to make modifications in the conventional CZ crystal puller for experiments, and develop a basic understanding of flow and temperature fields in the melt. Experiments to obtain data on crucible size, melt height, power requirement, growth and feed rates, appropriate location for addition of silicon charge and several other parameters which help in developing a commercial unit will be investigated.

In this project, the P.I.'s will investigate numerical methods leading to development of improved global ocean models suitable for climate studies. Enhancements will be added to a primitive equation model and a filtered model (both developed by the P.I. and collaborators). Major focus will be on : 1. Domain decomposition strategies and boundary-fitted coordinates to add boundary layers with higher order physics; 2. Conservation properties of efficient finite difference schemes; 3. Composite overlapping grid techniques for embedding the mixed layer in the larger models; and 4. Comparison of the PE model with tropical Atlantic data.

9414606 Prasad High yield, high performance microelectronic devices require large diameter silicon (Si) wafers with a high degree of crystallographic perfection, uniform and low axial and radial resistivity gradients, low oxygen impurity and highly uniform electrical and mechanical properties. Many of the inhomogenities in crystals grown by the Czochralski (CZ) method (which is used to manufacture almost all Si crystals for microelectronics applications) can be attributed to the non-steady nature of the growth kinetics due primarily to the continuous change in melt height from start to finish. As the CZ process is scaled up to grow large diameter crystals, the forces which produce flow instabilities and oscillations become much stronger. To overcome many of the shortcomings of the conventional CZ process, a polysilicon pellets-feed continuous Czochralski (CCZ) growth process will be investigated. By reducing the melt height and keeping it fixed, this novel process can suppress many kinds of unsteady kinetics and inhomogenities. A comprehensive program of modeling, simulation, design and experiments will be performed to develop a commercially viable CCZ process. To simulate three- dimensional (3D) transport processes in an irregular domain with free and/or moving boundaries and interfaces, a high resolution computer model based on multizone adaptive grid generation and curvilinear finite volume discretization will be developed. It will then be possible to examine accurately the effects of melt flow recirculation and oscillations, heat transfer from the melt and crystal, crystal/melt interface shape and its dynamics, impurity transport, and pellets melting in a range of parameters suitable for industrial processes. Non-invasive visualization of temperature (using liquid crystals) and flow fields, digital image processing and heat transfer experiments in an apparatus simulating the CZ system to obtain basic information on the physics of the process will be investigated. Computer reconstruction of 3D images from two-dimensional horizontal and vertical pictures will be attempted. The results from numerical computations and laboratory experiments will help in designing the CCZ growth experiments which will be conduced in a commercial puller at an industrial research facility to determine the optimal process conditions. This project builds on prior research demonstrating the feasibility of continuous Czochralski growth of silicon single crystals using small pellets instead of melting a large block of silicon. Anticipated high probability of success is further demonstrated by the industrial partner's commitment to allocate a researcher to this project. Successful completion of this project will break down the current technological barrier limiting the size of silicon single crystal that can be manufactured and lays the foundation for converting the current batch process to truly continuous process with the potential to increase the yield as well as quality. Successful commercialization of this technology will enable the U.S. to maintain its competitive edge in this important electronics market.

9310649 Prasad The equipment will primarily be used for ongoing research on continuous Czochralski (CCZ) crystal growth of silicon single crystals and thin film formation for VLSI/ULSI circuit fabrication. In addition, they may also help in conducting research on liquid encapsulated Czochralski growth of indium phosphide single crystals and in basic melting/solidification research. Computational research and full scale experiments in an industrial crystal puller have demonstrated that the velocity and temperature fields of CCZ growth process are inherently three dimensional and oscillatory except under special circumstances. To understand the physical phenomena underlying the CCZ melt flow and melting of solid pellets when dropped in a rotating pool of melt, and to examine the effect of process parameters on growth conditions, three dimensional visualization and imaging of field variables is necessary. The proposed video photography and image processing equipment, with the help of appropriate software, can perform this task on existing SUN workstations. The video animation of growth processes produced from the computational results, can be used for a theoretical study of the effect of governing parameters as well as for designing new laboratory and industrial experiments. The expanded scope of this research will help in faster development of this CCZ technique for commercial applications. If the crystal growth process can be understood better, it may be possible to grow more perfect crystals at faster rates, resulting in better devices at lower cost.

9303007 Prasad This project is a multidisciplinary, university-industry AMPP collaborative research program to develop a molecular dynamics (MD) simulation tool which can be used to create and develop new thin film technologies, improve the old ones, and study the effect of process parameters on film structure and its mechanical and electrical properties. Essential features of this MD model are: a suitable potential function(s); efficient algorithms for force evaluation and sorting of neighbor atoms; higher-order, adaptive time-interval integration schemes; an appropriate temperature control algorithm and an improved method for calculations of local and average film stresses. It can simulate three-dimensional thin film depositions on plane substrates and in vias for metallization of passivation of devices. By allowing the periodic boundary conditions to vary, this model can demonstrate the effect of substrate conditions, e.g., external stresses and temperature. The effect of gas impurity and ion bombardment can be studied by varying the descriptions of the deposited atoms. A hybrid approach where a via solution is built from the results for plane surfaces and corners is also proposed. Two different strategies, use of a massive parallel computer, and distributed computing on a cluster of workstations will be developed for computations for a large number of particles. Predictions of the PI will be compared with the experimental data obtained from the IBM and AT&T research laboratories. With the help of this simulation code, a deposition process can be designed on a computer and a range of optimized conditions for the growth of thin films of uniform structure and consistent properties can be predicted. A suitable visualization software can display the evolution process on a monitor screen which can be video recorded for further analysis. This research will be a major step in the direction of using molecular dynamics theory for micro-and nano-technolo gy, an area of significant future growth. ***

9503988 Prasad The object of the proposed research is to develop a parallelized multizone adaptive scheme for accurate and efficient simulations of materials processes of industrial importance. The final software will be able to simulate three-dimensional transient processes involving diffusion and convection of heat, mass, and species, and radiation heat transfer together with melting/solidification, flows induced by buoyancy and capillary forces, and effects of electrical and magnetic fields. The use of a generalized governing equation will allow consideration of many different materials with various phases in a single computational domain. The numerical scheme will employ (a) the multizone adaptive grid generation (MAGG) technique for the discretization of physical domains of arbitrary shape, and (b) the curvilinear finite-volume(CFV) approach for the discretization of the govening partial differential equations and development of the finite difference equations. An efficient parallel algorithm suitable for multiphase systems will be developed based on the massively-parallel distributed-memory MIMD techniques and will take advantage of the physics of the problem to develop a domain-decomposition strategy. Load balance, communication, and migration of elements will be given special attention in the development. The immediate implementation of this model will be made to the CZ and CCZ growth of silicon single crystals (a project sponsored by NSF and Ferrofluidics Corporation) and one-step in-situ synthesis and high pressure MLEK growth of indium phosphide crystals (an AFOSR project). The proposed parallel computer model will be able to simulate many kinds of complex materials processes involving free and moving boundaries that are not possible by the present techniques.

Abstract Prasad, V. The award is to partially support a workshop on "Thermal Aspects of Manufacturing and Materials Processing." The objective of the workshop is to bring together a cross section of people knowledgeable in areas of emerging technology and researchers with a strong interest in thermal processing to exchange information and to explore common technical areas. The workshop is directed towards industrial and academic participation. It will take place over two days in conjunction with the 1998 International Mechanical Engineering Congress and Exposition (to be held at Anaheim, California) and will involve presentations of current state-of-the-art, future trends, and critical thermal issues made by representatives from industry and federal laboratories and subsequent discussion by all attendees. The topics range from chemical vapor deposition for electronics to property measurements for model reliability and includes ceramic, laser, plasma, polymer and thermal processing, MEMS, nanostructures, and in-situ measurements. A printed report will be prepared for dissemination to government agencies and industry and web based version will be prepared for electronic access by academics and others.

This major research instrumentation (MRI) grant provides funding for setting up a state-of-the-art, integrated crystal growth and wafer manufacture research facility at the State University of New York at Stony Brook, which will comprise crystal growth, substrate manufacturing, material characterization, thermo-optical measurements and process modeling laboratories. The major instrumentation to be acquired through this grant includes: the next generation high pressure Czochralski crystal growth system with provisions for in-situ synthesis of compound materials as well as an applied magnetic field; a multizone modified Bridgman furnace with advanced instrumentation; an inner diameter wafering saw; a chemo-mechanical polishing apparatus; and a 2-axis/3-axis x-ray characterization instrument. They will add to the university's existing facilities for experiments, process modeling and virtual prototyping. These facilities will help to broaden the talent base available to address specific problems in the field of crystal growth and wafer manufacturing, and provide access to highly specialized and costly facilities that would be otherwise unavailable. The MRI grant will help in further expanding the university's research efforts in both basic and applied sciences, provide a focus to attract more industrial participation, and help in developing a better academic and research environment in this field. With the support of MRI funds, Stony Brook will be able to establish an integrated experimental and theoretical, industry/university/federal laboratory research program for semiconductor processing at the pre-device level that is non-existent in the country. It will allow validation of numerical models that cannot be accomplished without conducting carefully-designed experiments for a wide range of parameters, feasibility study of new concepts, design verification, and test of model-based feed-forward control algorithms. It will also serve as a clinic to which industry can visit for intellectual support, theoretical modeling and experimental testing. Research on both elemental and compound materials will be pursued with results directly applicable to electronics, opto-electronics, laser-based devices, photovoltaics, sensors and micro-electromechanical systems (MEMS).

The grant will partically support attendence of U.S. scientists at the Fourth ISHMT-ASME Heat and Mass Transfer Conference in Pune, India in January 2000. The American attendees will contribute as panelists
discussing research and educational programs, participate in special workshops which will be held in conjunction with the conference, and present state- of- the- art reviews. The conference will provide a forum for the synthesis of the knowledge base that has been developed and in isolating key issues to be addressed in future research. In the field of thermal science and technologies, India is one of the leading Asian countries and research performed by its scientists is of particular relevance to the developing nations and of interest to the global community. The conference will include workshops held off side on industrial research emerging thermal technologies solidification, computational fluid mechanics, and materials processing and manufacturing. Participation is expected to be of the order of 400, with 40 US and 50 European attendees.

ABSTRACT


Proposal Number: CTS 9910538
Principal Investigator: V. Prasad

This grant will support participation by US scientists, faculty, and graduate students at the Third International Workshop on Modeling in Crystal Growth.
The intent of the funding is to expand the research base and student participation.
The previous two workshops were held in Germany and Belgium and with the increased emphasis on crystal growth it is appropriate that a workshop be held in the United States. The workshop will cover a broad range of topics related to mathematical modeling and numerical analysis of the growth of single crystals and crystalline layers. It will focus on physical phenomena taking place at the macro-, meso-, and micro-scale, global modeling of the processes, model-based design of experiments, and the use of the models for prototyping and control. Speakers, who do not normally work in crystal growth but whose expertise will assist in understanding the growth process, will give presentations in the areas of thermal manufacturing, computational material processing, process optimization, virtual reality, and control. An abstract proceeding and a volume containing peer reviewed papers will be published.

CTS-0079494
Jon P. Longtin
State University of New York Stony Brook
MRI: Development of a Coherent Gradient-Sensing Tomographic Interferometer:
Application to 3D Transient Temperature, Concentration, and Refractive Index Meas-urement

Abstract

This project combines a novel interferometric measurement technique, Coherent Gradient-Sensing Interferometry (CGI), with multi-view tomography to develop a powerful new tool for transient, three-dimensional (3D) measurement of temperature, concentration, or density in fluid systems. The unique advantages of CGI over traditional interferometric techniques include: (1) complete insensitivity to vibration, (2) no reference-beam requirement, (3) continuously variable sensitivity, and (4) lower cost, and (5) more reliable operation. These features make a CGI-based instrument particularly well suited for portable and commercial applications. This novel instrument consists of a CGI interferometer capable of rotating around a transparent test cell to capture interferometric images at different angles, which are then used to compute transient, 3-D profiles of thermophysical properties such as temperature, concentration, or density for the fluid-thermal system in the test cell.

Measurement of three-dimensional, time-varying profiles of temperature, concentration, and density is critical for the understanding and optimization of many engineering, biological, and geophysical thermal-fluid systems. Examples include advanced materials processing; natural and forced convection, and surface-tension-driven heat transfer; mass transfer, and species pro-duction; and biological and bio-engineering phenomena. Such measurements are needed to vali-date computer simulations of such situations. The successful development of the CGI Tomo-graphic Interferometer provides, for the first time, direct, transient, 3-D measurement capabilities for transport phenomena in fluid-thermal systems. Some immediate applications of the instru-ment will include measuring temperature and concentration during simulated crystal growth, measuring temperatures during laser-induced surface-tension-driven flows, monitoring tracer concentrations in flow through mechanical heart valves, measuring temperature and concentra-tion during melting and solidification, and assessing 3D crack structures in transparent solids. A prototype instrument is also being developed that will be portable and available for other labo-ratories and local companies for evaluation and application. Furthermore, the instrument devel-opment itself is an excellent vehicle for training students in optical systems and image process-ing.

International research interaction and exchange of ideas, particularly in the field of emerging technologies, is in the best interest of United States. Several NSF-sponsored workshops have concluded that thermal issues play an important role in many of the critical areas. NSF support is requested to partially support a team of US young scientists to visit India in January 2002 to participate in the Fifth ISHMT-ASME Heat and Mass Transfer Conference (Calcutta), jointly sponsored by the Indian Society of Heat and Mass Transfer and the American Society of Mechanical Engineers. The US scientists will also visit several premier institutions including the recently-established Indian Institute of Technology, Guwahati, and Bangladesh. It will help in developing new ties with Bangladesh Society of Mechanical Engineers. A diversified group of US researchers including graduate students, post-doctoral fellows, and non-tenured faculty, will be partially supported from this grant, with special preference to under-represented groups. The visit will expand research interactions between the US and Indian scientists, build new contacts, improve our understanding of thermal science research and education in South Asia, and provide our young scientists with global perspectives of heat and mass transfer research.

0227869
Prasad

This award is to the Florida International University to support the activity described below for 24 months. The proposal was submitted in response to the Partnerships for Innovation Program Solicitation (NSF 02060).

Partners
The partners include Florida International University (Lead Institution), Baptist Health Systems of South Florida, Beckman Coulter, Inc, Bioheart, Inc, Boston Scientific Corporation, Cardis (Johnson & Johnson), IDEXX Laboratories, Inc, Medtronic Peripheral Vascular, Miami Cardiac and Vascular Institute, Miami Children's Hospital, Mt. Sinai Medical Center, Scion Cardio Vascular, Scion International, Inc, Syntheon, LLC, and The beacon Council.

The program establishes a permanent infrastructure for entrepreneurial and technology transfer activity at Florida International University with a focus on the biomedical industry. The infrastructure provides a venue for faculty and students to engage industry to transfer their developmental projects to commercialization. The region has a balanced mixture of large and small entrepreneurial corporations in the medical device and pharmaceutical industries that rank in the top 13 in the nation. In addition to commercialization of the research and development output of the university, an activity that will create economic wealth and new jobs, the activities supported by this award will educate students in biomedical engineering for the workforce for the regional industry.

The biomedical industry is growing very rapidly with large investments of venture capital. South Florida has established this industry as a top priority for economic growth. The goal of this proposal is to provide the workforce to enable the industry to grow in the region. The creation of new jobs will have a significant impact on the region. Florida International University currently ranks in the top 20 in graduation of Hispanic and African American engineers in the nation. In addition, the population of the region is high in underrepresented groups. Hence, the award broadens the participation of underrepresented groups in the technological and economic enterprise of the region.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

This award supports the renovation and modernization of approximately 2,900 square feet of space within the University of North Texas' (UNT) Center for Advanced Research and Technology (CART), located in the university's Discovery Park (about 4.5 miles north of the main campus). As part of CART, UNT will create a modern, model facility, called the UNT Nanofabrication Analysis and Research Facility (NARF), which is to be an open-access "one-stop-shop" for advanced device fabrication and analysis across multiple length and time scales. The renovations will consolidate currently spatially distributed, advanced characterization and analysis instruments; upgrade the space to include high speed cyber connectivity permitting remote access and control of these instruments; and integrate this space with a clean room and technology incubator.

Intellectual Merit: NARF will use "open system design" architecture to maximize collaboration and shared use of equipment, "integration for fabrication" to maximize entrepreneurial activities characterized by co-location of a clean room and technology incubator, and a "community/school-friendly" setting, where researchers share results and explain their work in real-time or via distance to visitors. The facility will host a unique trio of tools consisting of a dual-beam focused ion beam instrument, a high resolution transmission electron microscope, and a local electrode atom probe, capable of true atomic scale analysis of the structure and chemistry of materials, as well as many other advanced instruments, into direct proximity of one another. NARF will foster fundamental research involving nanoscale characterization and analysis applied to a wide variety of materials systems and devices, and will allow for the first time at UNT, true 3D characterization of the nanoscale structure and composition of specific components and failure sites in semiconductor devices, as well as interfaces in hybrid materials for aerospace, biomedical, and energy-related applications.

Broader Impacts: One of the primary impacts enabled by NARF will be the research training of graduate and undergraduate students, as well as post-docs and external researchers from industry, in the use of sophisticated characterization and analysis equipment. NARF will provide researchers a range of different equipment under one roof and allow them to appreciate the novel research possibilities afforded by these various techniques. Such an impact is not possible if the equipment is isolated and located at geographically scattered locations across the campus, as it is currently.

This Partnerships for Innovation (PFI) project from University of North Texas will create an innovative partnership among farmers, academic researchers, and industrial scientists and engineers to develop kenaf (a plant in the hibiscus family, related to okra and cotton)-based biomaterials for sustainable structured insulated panels for the built environment, especially in zero (net) energy applications. Kenaf is selected because of its ability to grow in arid conditions, where alternative plantings cannot be considered. From an engineering standpoint, it represents a domestic resource that has the same strength to weight ratio as glass fiber. Natural fibers in their as-harvested state have a porous structure that is often destroyed by the industrial processing through alkali treatment. Approaches based on placing the freshly harvested crop in river or pond water are not effective on a large scale. An alternative approach using bacteria based on selectivity for kenaf will be utilized through an academic-farmer partnership. The goal will be to develop technologically viable reinforcements that retain their natural features while reducing the environmental footprint associated with their processing.

The broader impacts from this research arise from the interdisciplinary partnership at all levels of the PFI. A successful effort could yield positive economic, environmental, and energy savings for both residential and commercial buildings, while meeting or exceeding the industrial standards. The platform of new multifunctional materials also has potential applications for commercially viable sustainable building products in many sectors (e.g., aerospace, packaging, and transportation). Efforts to integrate fiber process modifications will translate to job creation in rural segments with value-added markets improving the investment returns. The work is inherently interdisciplinary-- incorporating a variety of areas of engineering (biochemical, green, mechanical, and structural) and life cycle analysis--and through small-group interactive processes, promotes the direct involvement of graduate students early in the innovation value chain. Innovative academic-industrial research activities will be integrated with socially responsible entrepreneurship training, where doctoral students in each department will work together as an interdisciplinary Venture team, merging business and engineering innovation with sustainability concepts.

Partners at the inception of the project include the Knowledge-Enhance Partnership (KEP) unit, consisting of the University of North Texas, two small businesses: InnoVida Southeast (Miami, FL) and Ladonia Market Center (Ladonia, TX); and a federal agency: Agricultural Research Service, USDA (Lane, OK). In addition, there is another academic partner: Florida International University (Miami, FL).

Fluids under supercritical conditions, where distinct liquid and gas phases no longer exist, are good candidates for enhanced thermal transport and effective thermal control and management. Supercritical heat exchangers are promising solutions for direct solar energy conversion, power generation, thermal management of space systems, to name a few. However, research on supercritical heat transfer has been limited because of the lack of understanding of anomalous behaviors, characterized by large variations in thermophysical properties in a region around the critical point, and the associated thermal oscillations and fluctuations. This EAGER project will develop experimental capabilities to measure supercritical properties in the anomalous region to improve the fundamental understanding of supercritical fluids and their performance in heat transfer applications.<br/><br/>This EAGER project seeks to explore: (i) the use of anomalous behavior to achieve enhanced heat transfer, (ii) thermal management and control using a small variation in supercritical pressure, and (iii) change in critical temperature of supercritical fluid mixture to tune the temperature at which the heat dissipates. The project tasks are to obtain experimental data on critical properties for mixtures of CO2 with Ar and R134a and conduct natural convection experiments to demonstrate the effect of temperature and pressure in the anomalous region. If successful, this EAGER project could build the foundation of using supercritical fluid mixtures for heat dissipation at extreme temperatures and enable applications in solar thermal and power generation systems.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.