Two-Dimensional electron gases at complex oxide interfaces
Susanne Stemmer, Professor, Materials Department, University of California Santa Barbara
Thursday, April 11, 11:15 AM – 12:15 AM
E001 Scott Laboratory, 201 West 19th Avenue
Light reception to follow
Abstract: Two-dimensional electron gases at interfaces between two insulating oxides have attracted significant attention because they can exhibit unique properties, such as strong electron correlations, superconductivity and magnetism. In this presentation, we will discuss an example for such an interface, between the strongly correlated Mott insulator GdTiO3 and the band insulator SrTiO3. A fixed polar charge exists at these interfaces because of a polar discontinuity at the interface. The interfacial charge can be compensated by a high-density, two-dimensional electron gas (2DEG). At GdTiO3/SrTiO3 interfaces grown by molecular beam epitaxy, this results in a high-density 2DEG, of approximately 1/2 electron per surface unit cell, or 3×1014 cm-2, for all GdTiO3/SrTiO3 heterostructures, independent of the individual layer thicknesses and growth sequences. We will present measurements of quantum oscillations that provide insights into the nature of a 2DEG derived from the Ti d-states. We will report on electron correlation effects, such as magnetism and mass enhancement, in extremely high carrier density SrTiO3 quantum wells that can be obtained using these interfaces. Finally, we discuss the potential of oxide heterostructures for future electronic devices. The work was done in collaboration with Pouya Moetakef, Clayton Jackson, Tyler Cain, Leon Balents, Jim Allen, Jimmy Williams and David Goldhaber-Gordon.
Speaker Bio: Susanne Stemmer is Professor of Materials at the University of California, Santa Barbara. She received her Diploma in Materials Science from the Friedrich-Alexander University Erlangen-Nürnberg (Germany) and did her doctoral work at the Max-Planck Institute for Metals Research in Stuttgart (Germany). She received her doctoral degree from the University of Stuttgart in 1995. Following several postdoctoral positions she held an Assistant Professor position in Materials Science at Rice University from 1999 to 2002. In 2002, she joined the University of California, Santa Barbara, where she was promoted to Full Professor in 2008. Her research interests are in transmission electron microscopy techniques, in particular, the development of scanning transmission electron microscopy as a quantitative tool in materials science, novel dielectrics, oxide thin film growth and correlations between microstructure and electronic, dielectric and transport properties of oxide heterostructures. She has authored or co-authored more than 150 publications. Honors include an NSF Career Award, Fellow of the American Ceramic Society and Fellow of the American Physical Society.
Dr. Dev Chidambaram is an Associate Professor of Chemical and Materials Engineering Department at the University of Nevada, Reno. Abstract and bio to be provided.
IMR Special Seminar
Tuning Ionic Carriers in Solid State Materials for Electrochemical Devices and New Memristive Data Storage and Logic Concepts: Let`s Design the Twists
Jennifer L.M. Rupp, Electrochemical Materials, ETH Zurich
Monday, December 8 – 10:30 – 11:30 AM
Smith Seminar Room, 1080 Physics Research Building, 191 West Woodruff Avenue
The next generation energy conversion and storage, information memories and new neuromorphic computer logic concepts rely largely on the mass and charge transport engineering of oxygen ionic transport in materials. Here, the tuning of the defect kinetics in the solid state material building blocks and their interfaces defines the performances such as the respective power output or memory operation voltage and switch speed. Through this presentation the electro-chemo-mechanics and lattice strain engineering is being discussed as a new route for tuning material and device properties in ionic conducting oxide film structures up to new device prototypes. We will discuss basic fundamentals of oxygen ionic transport under strain and exemplify the impact on novel electrochemical devices such as for energy conversion and storage: “Strained Membranes for Energy Conversion,” “All Solid State Li-Ceramic Batteries,” and for data storage and logics “Strained Memristor micro-Dots for Information Storage and Logics to replace Transistors.”
Born in Germany in 1980, Jennifer Rupp studied at the University of Vienna in Austria mineralogy and crystallography and received her PhD in material science at the ETH Zurich in Switzerland in the group of Prof. L.J. Gauckler. From 2007 until end of 2010 she was group leader and senior scientist in the same electroceramics group. During this period in Zurich, she worked on ionic transport-structure relations and crystallization kinetics for solid state ionic conductor thin films, micro-solid oxide fuel cells their microfabrication, electrochemistry and system aspects. In 2011 she was for a short period researcher at the National Institute of Materials Science (NIMS) in Tsukuba Japan working on oxide memristors for information storage, strain-charge transport interaction in mixed ionic electronic conductors and protonic fuel cells and materials. From spring 2011 to mid 2012 she joined the Massachusetts Institute of Technology (MIT) USA where she was affiliated and working in two groups, namely with Prof. H. Tuller in the Crystal Physics and Electroceramics laboratory (Dept. of Materials) on resistive memories and with Prof. B. Yildiz on the connection of DFT computation to experiments on strain-charge transport interaction in solid electrolytes at the Laboratory for Electrochemical Interfaces (Dept. of Nuclear Science).
Rupp holds the non-tenure track Swiss National Science Foundation (SNF) professorship entitled “redox-based resistance switching memories” (2012-2016) at ETH, is a guest associate professor at Kyushu University Japan (2011-open) and the International Institute for Carbon-Neutral Energy Research (I2CNER) Japan (2013-open), is an elected member of the European Academy of Science for Chemistry (2012-2015) and on the editorial board of the Journal of Electroceramics, Springer.
Recently, she accepted the nomination and mandat by the Swiss Federal Department of Environment, Transport, Energy and Communication to serve as a member on the new Swiss Energy Technology-fund board on invitation by Federal Councillor Doris Leuthard starting in 2015.
Awards include the recent nomination as one of the top 40 international scientists under the age of 40 to speak at the World Economic Forum (WEF) in China on new innovative Materials and Devices for Global Energy Challenges in 2014, the Spark Award by ETH Zurich for the most innovative and economically important invention of the year for a new memristor information storage concept in 2014, Kepler award “new materials in energy technology” by the European Academy of Science, 1st prize Young Scientist Awards by the International Solid State Ionics Society, ETH Zurich`s Medal for PhD excellence, 1st prize Austrian Chemical Society award for her diploma thesis.
Her main research interests are on materials development and structure-transport relations for information memory storage, microsystems and new solid state energy conversion and storage systems. This includes new device design concepts and performance testing.
Antimonide Materials for Mid-Infrared Photonic Detectors and Focal Plane Arrays
Director, Center for High Technology Materials, Professor and Regents’ Lecturer, Department of Electrical and Computer Engineering, University of New Mexico
Infrared imaging (3-25mm) has been an important technological tool for the past sixty years since the first report of infrared detectors in 1950s. There has been a dramatic progress in the development of infrared antimonide based detectors and low power electronic devices in the past decade with new materials like InAsSb, InAs/GaSb superlattices and InAs/InAsSb superlattices demonstrating very good performance. One of the unique aspects of the 6.1A family of semiconductors (InAs, GaSb and AlSb) is the ability to engineer the bandstructure to obtain designer band-offsets. Our group (www.krishnairlab.com) has been involved with the vision of the 4th generation of infrared detectors and is one of two university laboratories in the country that can undertake “Design to Camera” research and realize focal plane arrays.
My talk will revolve around three research themes.
The first theme involves the fundamental investigation into the material science and device physics of the antimonide systems. I will describe some of the challenges in these systems including the identification of defects that limit the performance of the detector. The use of “unipolar barrier engineering” to realize high performance infrared detectors and focal plane arrays will be discussed.
The second theme will involve the vision of the 4th Gen infrared imaging systems. Using the concept of a bio-inspired infrared retina, I will make a case for an enhanced functionality in the pixel. The key idea is to engineer the pixel such that it not only has the ability to sense multimodal data such as color, polarization, dynamic range and phase but also the intelligence to transmit a reduced data set to the central processing unit. The design and demonstration of meta-infrared detectors will be discussed.
In the final theme, I will describe the role of infrared imaging in bio-medical diagnostics. In particular, I will highlight some work on using infrared imaging in the early detection of skin cancer and for detection of flow in cerebral shunts. Using dynamic thermal imaging on over 100 human subjects, a sensitivity >95% and specificity >83% has been demonstrated. Commercialization of this technology will also be discussed.
Sanjay Krishna is the Director of the Center for High Technology Materials and Professor and Regents Lecturer in the Department of Electrical and Computer Engineering at the University of New Mexico. Sanjay received his M.S. from IIT, Madras, MS in Electrical Engineering in 1999 and PhD in Applied Physics in 2001 from the University of Michigan. He joined UNM as a tenure track faculty member in 2001. He currently heads a group of 15 researchers involved with the development of next generation infrared imagers. Sanjay received the Gold Medal from IIT, Madras, Ralph Powe Junior Faculty Award, IEEE Outstanding Engineering Award, ECE Department Outstanding Researcher Award, School of Engineering Jr Faculty Teaching Excellence Award, NCMR-DIA Chief Scientist Award for Excellence, the NAMBE Young Investigator Award, IEEE-NTC, SPIE Early Career Achievement Award and the ISCS Young Scientist Award. He was also awarded the UNM Teacher of the Year and the UNM Regents Lecturer award. Sanjay has more than 200 peer-reviewed journal articles (h-index=42), two book chapters and seven issued patents. He is the co-founder and CTO of Skinfrared, a UNM start-up involved with the use of IR imaging for dual use applications including early detection of skin cancer. He is a Fellow of IEEE, OSA and SPIE.
IMR Distinguished Lecture Series presents
21.25% World Efficiency Record with Multi-Crystalline p-type Silicon Solar Cells: Closing the Gap with n-type Mono
Vice President, Chief Scientist and Vice-Chair of State Key Laboratory, Trina Solar
Friday, June 17, 10:00 AM
E525 Scott Laboratory, 201 West 19th Avenue, Reception to follow
Multicrystalline Silicon technologies represents more than 65% of 2015 global shipments. Over the last two years, the best p-type multicrystalline silicon solar cells developed by Trina Solar have reached new efficiency records, up to 20.86% in 2014 and 21.25% in 2015. These achievements result from improvements of all aspects of the solar cell fabrication: contamination control, development of high-performance multi-crystalline silicon wafers, cell design and process optimization. Analysis show that efficiencies above 22% are possible with p-type multicrystalline and could be reached in the next few years.
Pierre J. Verlinden is Vice-President and Chief Scientist at Trina Solar, the world’s largest PV manufacturer. He is also Vice-Chair of the State Key Laboratory of PV Science and Technology. Dr. Verlinden has been working in the field of photovoltaics for more than 35 years and has published over 170 technical papers and contributed to a number of books. Before joining Trina Solar, Dr. Verlinden served as Chief Scientist or head of R&D department in several other PV companies in USA and Australia, including SunPower, Origin Energy, Amrock and Solar Systems.
Energy and Environment Discovery Themes Seminar
Ardeshir Contractor, Founder and CEO, Kiran Energy
Factors Influencing Product Innovation in Solar Energy Markets
Tuesday, February 7, 2017
2:00 – 3:30 PM
Mason Hall, 2nd Floor Rotunda, 250 West Woodruff Avenue, Columbus, Ohio 43210
Reception immediately following program
Registration: Discovery Themes Survey RSVP
Co-sponsored by the Materials and Manufacturing for Sustainability Discovery Theme focus area, Institute for Materials Research and Fisher College of Business
In 2010, Ardeshir Contractor raised $80M from three US private equity investors and a joint venture with First Solar to build Kiran Energy – a solar energy utility at the forefront of India’s solar energy market. In its journey, the company examined and deployed multiple innovative products seeking higher performance with leap-frog cost economics and also set early benchmarks in non-recourse project financing.
This talk will focus on both product innovation in solar energy and innovation in sustainability financing. The size of the solar energy market is significant – nearing an annual investment in solar energy new power plants of $250B. Solar modules, inverters, monitoring systems, and storage comprise most of this number. The addressable market for the introduction of new solar technology or product innovation is very large and allows for immense scalability. The solar market is truly global both in terms of markets and suppliers.
Product innovation in solar energy
The seminar will include a review of effective product introductions, many of which exhibit similar characteristics of product astuteness and a drive to forward-looking performance and commercial targets. Not all successes have been smooth, some of the leaders have had setbacks including unforeseen technical issues. The large amounts of investment required for manufacturing and selling implied a constant requirement to maintain the path and story of strong financial returns. Blending aggressive technology and commercial innovation appears to have worked. It is useful to examine how such dual innovation is embedded in a product offering.
Innovation in sustainability financing
Solar energy components and systems are expected to function for 20-30 years and the overlay of bankability and financing are critical especially for innovative technology. The long-term nature of the finance and returns – coupled with the very scale of the explosive investment needs – has required the development of new financial market products and market sources. Very quickly the sustainable financing story has evolved from government and agency support to mainline financial markets. However, analytical processes and the banking institutions are still retooling for this. In addition, an asset that functions over such a long term would require financial evaluation and analysis methods that align with its characteristics. The approach is to describe these efforts, the evolution of sustainable financing and what it implies to product innovation.
Ardeshir Contractor chairs India’s solar energy task force at the Federation of Indian Chambers of Commerce and partners with the government in developing policy, standards, and technological opportunity for Indian manufacture in solar. He is also an adjunct Research Associate with Edhec Infrastructure Institute, Singapore, investigating long term asset finance principles. In December 2015, he addressed the United Nations at the Paris Climate Change Conference (COP21), and he was deeply involved with the UN Environment Programme’s Enquiry on the design of a global sustainable financial system. Mr. Contractor has served on the boards of Nature India, Government Committees, and Clean Energy Ministerial. He received his Masters in Mechanical Engineering from The Ohio State University, was the recipient of the 2015 College of Engineering’s Distinguished Alumni Award, and is currently an Executive in Residence with the Institute for Materials Research.
Ohio State’s materials research engine and the Discovery Themes program it drives are helping to position Ohio State as a model 21st-century land-grant university focused on interdisciplinary collaboration and innovation. The depth and breadth of our faculty, the ingenuity of our students and the global reach of our partners is at the heart of Discovery at Ohio State.