EMA 2013 Plenary Speakers
Don’t miss this year’s plenary speakers
Ramamoorthy Ramesh, Purnendu Chatterjee Chair Professor, Materials Science/Physics, University of California, Berkeley
Title: Pulsed Laser Deposition : God’s Gift to Complex Oxides Creating New States of Matter with Oxide Heteroepitaxy
Abstract: The advent of high temperature superconductivity in cuprates was a global trigger point for a comprehensive revisit to all transition metal oxides that exhibit a rich spectrum of functional responses, including magnetism, ferroelectricity, highly correlated electron behavior, superconductivity, etc. The basic materials physics of such materials provide the ideal playground for interdisciplinary scientific exploration. By far, one of the most important elements of this resurgence of worldwide interest in these materials has been, and continues to be, pulsed laser deposition (PLD). Since its introduction to the field of oxides by Venkatesan and co-workers at Bellcore/Rutgers, it has taken the world by storm. I have personally been one of the major beneficiaries of this explosion. Its relative simplicity and the ability to transfer the stoichiometry of complex oxides onto a substrate with unprecedented perfection has been one of they key reasons for the proliferation. The technique has evolved significantly since the early days in the late eighties; several surface tools have now become standard in PLD and I am sure they will continue to evolve even more. Over the past decade we have been exploring the science of complex oxide materials in thin film form by creating epitaxial heterostructures and nanostructures. Among the large number of materials systems, there exists a small set of materials that exhibit multiple order parameters; these are known as multiferroics. Our model multiferroic is BiFeO3, which has ferroelectric and antiferromagnetic order well above room temperature. We use a combination of laser MBE (UHV PLD with surface analysis) and chemical vapor deposition to create our model heterostructures. The physical properties are probed using a combination of piezoforce microscopy, conducting AFM, transmission electron microscopy, photoemission spectromicroscopy and optical techniques. In this talk, I will describe our progress to date on the exciting possibility of switching ferromagnetism with an electric field.
Biography: Ramesh graduated from the University of California, Berkeley with a PhD in 1987. Previously, he was Distinguished University Professor at the University of Maryland College Park. From 1989-1995, at Bellcore, he initiated research in several key areas of oxide electronics, including ferroelectric nonvolatile memories. His landmark contributions in ferroelectrics came through the recognition that conducting oxide electrodes are the solution to the problem of polarization fatigue, which for 30 years, remained an enigma and unsolved problem. His current research interests include thermoelectric and photovoltaic energy conversion in complex oxide heterostructures. He has published extensively on the synthesis and materials physics of complex oxide materials. He received the Humboldt Senior Scientist Prize and Fellowship to the American Physical Society (2001). In 2005, he was elected a Fellow of American Association for the Advancement of Science as well as the David Adler Lectureship of the American Physical Society. In 2007, he was awarded the Materials Research Society David Turnbull Lectureship Award, in 2009, he was elected Fellow of MRS and is the recipient of the 2010 APS McGroddy New Materials Prize. From December 2010 to August 2012 he served as the Founding Director of the SunShot Initiative at the U.S. Department of Energy, overseeing and coordinate the R&D activities of the U.S. Solar Program. In 2011, he was elected to the National Academy of Engineering.
Rainer Waser, director, Institute of Solid State Research (IFF) at the HGF Research Center, Jülich, Germany
Title: Complexity at Work – Nanoionic Memristive Switches
Abstract: A potential leap beyond the limits of Flash (with respect to write speed, write energies) and DRAM (with respect to scalability, retention times) emerges from nanoionic redox-based switching effects encountered in metal oxides (ReRAM). A range of systems exist in which highly complex ionic transport and redox reactions on the nanoscale provide the essential mechanisms for memristive switching. One class relies on mobile cations which are easily created by electrochemical oxidation of the corresponding electrode metal, transported in the insulating layer, and reduced at the inert counterelectrode (so-called electrochemical metallization memories, ECM, also called CBRAM). Another important class operates through the migration of anions, typically oxygen ions, towards the anode, and the reduction of the cation valences in the cation sublattice locally providing metallic or semiconducting phases (so-called valence change memories, VCM). The electrochemical nature of these memristive effects triggers a bipolar memory operation. In yet another class, the thermochemical effects dominate over the electrochemical effects in metal oxides (so-called thermochemical memories, TCM) which leads to a unipolar switching as known from the phase-change memories. In all systems, the defect structure turned out to be crucial for the switching process. The presentation will cover fundamental principles in terms of microscopic processes, switching kinetics and retention times, and device reliability of bipolar ReRAM variants. Passive memory arrays of ReRAM cells open up the paths towards ultradense and 3-D stackable memory and logic gate arrays. The selector issue of passive memories will be described, emphasizing complementary resistive switches as a potential solution. Despite exciting results obtained in recent years, several challenges have to be met before these physical effects can be turned into a reliable industrial technology.
Biography: Waser received his PhD in physical chemistry at the University of Darmstadt in 1984, and worked at the Philips Research Laboratory, Aachen, until he was appointed Professor at the faculty for Electrical Engineering and Information Technology of the RWTH Aachen University in 1992 and director of the Institute for Electronic Materials at the Forschungszentrum Jülich, in 1997. He is member of the Emerging Research Devices working group of the ITRS, and he has been collaborating with major semiconductor industries in Europe, the US, and the Far East. Since 2002, he has been the coordinator of the research program on nanoelectronic systems within the Germany national research centres in the Helmholtz Association. In 2007, he has been co-founder of the Jülich-Aachen Research Alliance, section Fundamentals of Future Information Technology (JARA-FIT). Together with Professor Wuttig, he heads a collaborative research center on resistively switching chalcogenides for future electronics (SFB 917) which comprises of 14 institutes within JARA-FIT and has been funded by the German national science foundation (DFG) since 2011.
Susan Trolier-McKinstry, Professor of Ceramic Science and Engineering Co-director Nanofabrication Facility, Pennsylvania State University
Title: Designing Piezoelectric Films for Microelectromechanical Systems (MEMS)
Abstract: Piezoelectric thin films are of increasing interest in low voltage microelectromechanical systems (MEMS) for sensing, actuation, and energy harvesting. They also serve as model systems to study fundamental behavior in piezoelectrics. Piezoelectric MEMS devices range over a wide range of length scales. On the extreme upper end are large area devices for applications such as adaptive optics. In this case, the piezoelectric film can be used to produce local deformation of a mirror surface, in order to correct figure errors associated with fabrication of the component or to correct for atmospheric distortion. For example, should a mission such as Gen-X be flown, it would require up to 10,000 m2 of actuatable optics in order to correct the figures of the nested hyperboloid reflecting segments. In this case, the “micro” in “microelectromechanical systems” is clearly a misnomer, although the fabrication techniques would involve conventional micromachining for patterning of the electrodes. Many Piezoelectric MEMS devices are fabricated at intermediate length scales (tens of microns to 1 cm). Here, examples will be given of piezoelectric energy harvesting devices. We have recently demonstrated improvements in the energy harvesting figure of merit for the piezoelectric layer by factors of 4 – 10. Finally, piezoelectric MEMS are also attracting attention at a substantially smaller size scale (tens of nm) as a potential replacement for CMOS electronics. Examples of the materials choice as well as specific devices at all three of these length scales will also be discussed.
Biography: Coming soon.