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Jeff is currently a Distinguished Member of Technical Staff at Sandia National Laboratories, and Chief Scientist of its Energy Frontier Research Center for Solid-State-Lighting Science. His work involves integrated science, technology and economic modeling in Solid-State Lighting and other areas. He is also exploring embedded-network models of the evolution of social knowledge – an emerging approach to the field of “evolutionary epistemology.”
During 2000-2001 Jeff served as vice-president of R&D at E2O
Communications, Inc., a U.S.-based pre-IPO fiber communications components
company. During 1993-2000, he served
as manager of various technical groups at Sandia National Laboratories in the
area of compound semiconductor materials and devices. In 1998, he took a sabbatical at the
SCIENCE OF SCIENCE AND COMPLEX ADAPTIVE SYSTEMS
(Sandia National Laboratories, Albuquerque, NM, June 5-7,2013; J.Y. Tsao, G. R. Emmanuel, T. Odumosu, A.R. Silva, V. Narayanamurti, G.J. Feist, G.W. Crabtree, C.M. Johnson, J.I. Lane, L. McNamara, S.T. Picraux, R.K. Sawyer, R.P. Schneider, C.D. Schunn and R. Sun; Science, Technology and Public Policy Program, Belfer Center for Science and International Affairs, Harvard Kennedy School, December, 2013.
The purpose of this Forum and Roundtable was to initiate a dialog between the two communities: distinguished practitioners of the art of research and experts in the emerging science of research. The Forum and Roundtable was held at Sandia National Laboratories with a dual focus: to identify science that can be applied to improving how research is done and to identify ways in which Sandia could apply such to its own processes.
Engineering the Ultimate Dynamical Social System: what we know and don’t know about how scientists do science
Talk given at Complex 2012 (Santa Fe, 2012) (SAND 2012-10354C).
In this talk, we discuss how the system of science is a complex adaptive system and how it might be analyzable within a framework of a co-evolving dual network of people and ideas.
(Curtis M. Johnson, George A. Backus, Theresa J. Brown, Richard Colbaugh, Katherine A. Jones, Jeffrey Y. Tsao) (SAND 2011-9347P and SAND 2012-3320) (October 2011)
In this white paper, we make a case for Sandia National Laboratories investments in complex adaptive systems science and technology (S&T) -- investments that could enable higher-value-added and more-robustly-engineered solutions to challenges of importance to Sandia’s national security mission and to the nation.
A Brief History of Sandia National Laboratories and the Department of Energy’s Office of Science: Interplay between Science, Technology, and Mission
(Jeff Tsao, Jerry Simmons, Sam Collis, Andy McIlroy, Sam Myers, Tom Picraux, Fred Vook) (SAND 2011-5462) (October 2011)
In this report, we review the history of Sandia’s fundamental science programs supported by the Office of Science. We present: (a) a technical and budgetary snapshot of Sandia’s current programs supported by the various sub-offices within DOE-SC; (b) statistics of highly-cited articles supported by DOE-SC; (c) four case studies (ion-solid interactions, combustion science, compound semiconductors, advanced computing) with an emphasis on mutually beneficial interactions between science, technology, and mission; and (d) appendices with key memos and reminiscences related to fundamental science at Sandia.
(Jeff Tsao) (SAND 2013-7804 P) (June 2011)
This presentation was given at a strategic planning discussion meeting at Sandia, and discusses bi-translational S&T, something that might be called a virtuous “Casimir’s Spiral,” in which science leads to new technology, while technology leads to new science.
Galileo’s Stream: A Framework for Understanding Knowledge Production (Jeff Tsao, Kevin Boyack, Mike Coltrin, Jessica Turnley, Wil Gauster) (SAND 2006-7622J) (Research Policy 37, 330-352) (March 2008)
This paper introduces a new framework for understanding knowledge production in which: knowledge is produced in stages (along a research to development continuum) and in three discrete categories (science and understanding, tools and technology, and societal use and behavior); and knowledge in the various stages and categories is produced both non-interactively and interactively.
Consumer Preferences and Funding Priorities in Scientific Research (Jeff Tsao) (Science and Public Policy 16, 294-298) (October 1989)
This paper discusses the possibilities for a de-centralized market-oriented system for funding scientific research, in which researchers receive a form of royalty for the use of their published papers.
Solid-State Lighting: An Energy Economics Perspective (Jeff Tsao, Harry Saunders, Randy Creighton, Mike Coltrin, Jerry Simmons) (SAND 2010-1559 J) (Journal of Physics D 43, 354001 (2010))
In this paper, we provide estimates of the potentially massive shifts due to solid-state lighting of (a) the consumption of light, (b) the human productivity and energy use associated with that consumption, and (c) the semiconductor chip area inventory and turnover required to support that consumption. For past behavior, we use recent studies of historical and contemporary consumption patterns analyzed within a simple energy-economics framework (a Cobb-Douglas production function and profit maximization). For extrapolations into the future, we use recent reviews of believed-achievable long-term performance targets for solid-state lighting. We also discuss ways in which the actual magnitudes could differ from the baseline magnitudes of these shifts. These include: changes in human societal demand for light; possible demand for features beyond lumens; and guidelines and regulations aimed at economizing on consumption of light and associated energy.
The World’s Appetite for Light: Empirical Data and Trends Spanning Three Centuries and Six Continents (Jeff Tsao, Paul Waide) (SAND 2008-4246J) (LEUKOS 6, 259-281) (Apr 2010)
In this paper, we collected and self-consistently analyzed data for per-capita consumption of artificial light, per-capita gross domestic product, and ownership cost of light. The data span a wide range (three centuries, six continents, five lighting technologies, and five orders of magnitude), and are consistent with a linear variation of per-capita consumption of light with the ratio between per-capita gross domestic product and ownership cost of light. No empirical evidence is found for a saturation in per-capita consumption of light, even in contemporary developed nations. Finally, we extrapolate to the world in 2005, and find that 0.72% ($437B/yr) of world gross domestic product and 6.5% (29.5 Quads/yr) of world primary energy was used to produce 130 Plmh/yr of artificial light.
The Rebound Effect: An Analysis of the Empirical Data for Lighting (Jeff Tsao, Paul Waide, Harry Saunders) (Dec 2008) (SAND 2008-7959C) with notes
This talk was given at
the 28th USAEE/IAEE North American Conference in
These viewgraphs are
based on a tutorial lecture given for a high school physics class at the
Basic Research Needs in Solid-State Lighting (Julie Phillips, Paul Burrows, Chairs) (October 2006)
This report is based on a U.S. Department of Energy Office of Basic Energy Science’s Workshop on Solid-State Lighting (SSL), May 22–24, 2006, chaired by Julie Phillips and Paul Burrows. It examines the gap separating current state-of-the-art SSL technology from an energy efficient, high-quality, and economical SSL technology suitable for general illumination; and identifies the most significant fundamental scientific challenges and research directions that would enable that gap to be bridged.
This white paper asks and answers a series of questions regarding the potential of the sun to supply energy to the world. The questions are drawn in large part from the U.S. Department of Energy Office of Basic Energy Science’s recent report on Basic Research Needs in Solar Energy Utilization. The answers are given in a format suitable for a lay technical audience, and are supplemented by detailed calculations and comprehensive references.
Basic Research Needs in Solar Energy Utilization (Nate Lewis, George Crabtree, Chairs) (October 2005)
This report is based on a U.S. Department of Energy Office of Basic Energy Science’s Workshop on Solar Energy Utilization, April 18–21, 2005, chaired by Nate Lewis and George Crabtree. It examines the challenges and opportunities for the development of solar energy as a competitive energy source and identifies the technical barriers to large-scale implementation of solar energy and the basic research directions showing promise to overcome them.
semiconductor materials and devices
This is a book started in
2002, worked on for about a year, then abandoned. Its intent was to have been to provide an integrated
guide to the science, technology and applications of the compound III-V
semiconductors. Its unique aspect was
to have been its emphasis and organization around an objective database (linked file is in procite
format) of the most highly-cited journal articles and
Optically-pumped long-wavelength vertical-cavity surface-emitting laser with high modulation bandwidth (MV Ramana Murty, D Xu, CC Lin, CL Shieh, JY Tsao, J Cheng, Appl Phys Lett 86, 061108, 2006)
Electrically pumped long-wavelength VCSEL with air gap DBR and methods of fabrication (CL Shieh, JY Tsao, US Patent 6,696,308, February 24 2004)
Segmented-mirror VCSEL (JY Tsao, CL Shieh, PD Dapkus, J Yang, US Patent 6,594,294, July 15 2003)
Semiconductor Epitaxy: Science, Technology and Applications 40MB (July-November 1998) (SAND 2007-1800P)
This series of twelve
lectures was given over four months at the
This book gathers together the basic materials science principles that apply to MBE, and treats in great depth its most important aspects. Throughout, it makes use of thermodynamic and statistical calculations based on intuitive and physically motivated semi-empirical models.
(Mary Crawford, Jon Wierer, Art Fischer, George Wang, Dan Koleske, Ganesh Subramania, Mike Coltrin, Jeff Tsao) Chapter to be published in D.L. Andrews, Ed., “Photonics Volume 3: Photonics Technology and Instrumentation” (Wiley, 2013)
Solid-state lighting has made tremendous progress over the past decade, with the potential to make much more progress over the coming decade. In this chapter, we review the current status of solid-state lighting relative to its ultimate potential to be “smart” and ultra-efficient. Smart, ultra-efficient solid-state lighting would enable both very high “effective” efficiencies (as defined in subsection 2.3), as well as potentially large increases in human productivity. To achieve ultra-efficiency, phosphors must eventually give way to multi-color semiconductor electroluminescence; we review some of the technological challenges associated with such electroluminescence at the semiconductor level. To achieve smartness, additional characteristics such as the ability to control light flux and spectra in time and space will be important; we review some of the technological challenges associated with achieving these characteristics at the lamp level, as well as some of the potential future system applications that such smartness might enable.
(Jon Wierer, Jeff Tsao, Dmitry Sizov) Laser & Photonics Reviews (August, 2013).
Solid-state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light-emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state-of-the-art input-power-density-dependent power conversion efficiencies; potential improvements both in their peak power-conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.
(Sasha Neumann, Jon Wierer, Wendy Davis, Yoshi Ohno, Steve Brueck, Jeff Tsao) Optics Express 19, A982-990 (2011) SAND2011-2743J.
Solid-state lighting is currently based on light-emitting diodes (LEDs) and phosphors. Solid-state lighting based on lasers would offer significant advantages including high potential efficiencies at high current densities. Light emitted from lasers, however, has a much narrower spectral linewidth than light emitted from LEDs or phosphors. Therefore it is a common belief that white light produced by a set of lasers of different colors would not be of high enough quality for general illumination. We tested this belief experimentally, and found the opposite to be true. This result paves the way for the use of lasers in solid-state lighting.
Solid-state lighting: ‘The case’ 10 years after and future prospects (Roland Haitz, Jeff Tsao) Physica Status Solidi A 208, 17-29 (2011).
Ten years ago, a white paper titled “The Case for a National Research Program on Semiconductor Lighting” outlined the promise and potential of semiconductor light-emitting diodes (LEDs) for general illumination. Since then, investments in the now-renamed field of solid-state lighting (SSL) have accelerated and considerable progress has been made, not always in the directions envisioned at the time. In this paper, two of the original four authors comment on the white paper’s hits and misses, while making the original white paper available archivally as supplemental online material. Finally, we make new predictions for the coming 10-20 years.
Solid-State Lighting: An Integrated Human Factors, Technology and Economic Perspective (Jeff Tsao, Mike Coltrin, Mary Crawford, Jerry Simmons) (July 2010) (SAND 2009-5551J) (Proceedings of the IEEE 98, 1162-1179)
In this article, we present a high-level overview of solid-state lighting, with an emphasis on white lighting suitable for general illumination. We characterize in detail solid-state lighting’s past and potential-future evolution using various performance and cost metrics, with special attention paid to inter-relationships between these metrics imposed by human factors, technology and economic considerations.
This talk was given at the International Conference on Metal-organic Vapor Phase Epitaxy (ICMOVPE) May 24 2010 in Lake Tahoe, NV.
The Next Semiconductor Revolution: This Time It’s Lighting! (Jeff Tsao) (Mar 2010) (SAND 2010-1957P) and video
This tutorial talk for students and the general public was given at the Albuquerque Academy March 31 2010 in Albuquerque NM.
(Lighting and) Solid-State Lighting: Science, Technology, Economic Perspectives (Jeff Tsao) (Jan 2010) (SAND 2010-1090C) and video
This talk was given at Photonics West Jan 26 2010 in San Francisco, CA.
Research challenges to ultra-efficient inorganic solid-state lighting (Julie Phillips, Mike Coltrin, Mary Craford, Art Fischer, Mike Krames, Regina Mueller-Mach, Gerd Mueller, Yoshi Ohno, Lauren Rohwer, Jerry Simmons, Jeff Tsao) (SAND 2007-5470J) and figures (Laser and Photonics Reviews 1, 307-333 (November 2007)
This review article discusses approaches to inorganic solid-state lighting that could conceivably achieve ultra-high (70% or greater) efficiency, and the significant research questions and challenges that would need to be addressed if one or more of these approaches were to be realized.
recursive process for mapping and clustering technology literatures: case
study in solid-state lighting (
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