2009 Tutorials Session
Chair: Fred Walker, Yale University
Speaker 1: Daniel Worledge, IBM
“Magnetic Memory Applications”
Speaker 2: M. L. Lee from Yale
“Solar Cell Materials”
Speaker 3: Robert Wallace, University of Texas
“Challenges for High-K Dielectrics on High Mobility Channels”
Speaker 4: Dr. Ted Moise, Texas Instruments
"Ferroelectrics and Ferroelectric Devices"
D. C. Worledge
IBM Research Division, T. J. Watson Research Center
Abstract
MRAM uses magnetic layers to store information, and is poised to become an important player in the memory market with its unique combination of speed, nonvolatility, and endurance. This tutorial introduces the physics, materials, devices, and technology of MRAM. The tutorial does not assume any background in the field- topics are developed starting from basic principles. A broad perspective is given, covering the history of the field through areas of active research. Topics include Stoner-Wohlfarth MRAM, Toggle MRAM, and detailed coverage of Spin Torque MRAM.
Short Bio
Dr. Worledge received a BA with a double major in Physics and Applied Mathematics from UC Berkeley in 1995. He then received a PhD in Applied Physics from Stanford University in 2000, with a thesis on spin-polarized tunneling in oxide ferromagnets. After joining the IBM T. J. Watson Research Center as a Post-doc, he became a Research Staff Member in 2001, working on fast turn-around measurement methods for magnetic tunnel junctions. In 2003, Dr. Worledge became the manager of the MRAM Materials and Devices group. His current research interests include magnetic devices and their behavior at small dimensions.
Ted Moise, Ph.D.
Non-Volatile Memory Department Manager
Analog Technology Development
Texas Instruments
Short Bio
Ted Moise earned B.S. degrees in physics and engineering from Trinity College, Hartford, CT, in 1987 and his Ph.D. in electrical engineering from Yale University in 1992. While at Yale, he earned the Harding Bliss prize for excellence in engineering and applied science. Following graduation, Ted joined Texas Instruments where he was responsible for the development of high-performance III-V quantum-effect devices and circuits.
In 1997, Ted and his colleagues at TI started work on the development of embedded ferroelectric memory devices and circuits. This group demonstrated the first operation of low-voltage, high-density, embedded ferroelectric memory in 2002. In conjunction with Ramtron International Corporation, this group has also produced the first high-density (4Mb) ferroelectric memory products on an advanced (130nm) silicon technology node. Ted was presented with an outstanding achievement award at the 2008 ISIF conference for this work.
Ted is a distinguished member of TI's technical staff and is currently the non-volatile memory department manager within TI's Analog Technology Development organization. Ted has authored or co-authored over 60 papers, served as conference and session chair for several international technical conferences, presented numerous invited lectures, and holds more than 30 issued patents.
Robert M. Wallace
Materials Science and Engineering
University of Texas at Dallas
“Challenges for High-K Dielectrics on High Mobility Channels”
Abstract
Scaling integrated circuits beyond the 22 nm node has several challenges. The use of Si-based transistor devices results in performance concerns attributed to parasitic losses, which are worse as dimensional scaling continues. To address this challenge, channel materials with higher transconductance are being considered, including Ge and III-V semiconductors. For conventional MOS structures, the control of the channel/gate dielectric interface is crucial, and formidable challenges are encountered with these materials systems. This tutorial will examine the issues that must be addressed and recent progress in the field.
Short Bio
Robert M. Wallace received the Ph.D. (1988) in Physics at the University of Pittsburgh. He then was a postdoctoral research associate in the Department of Chemistry at the Pittsburgh Surface Science Center. In 1990, he joined Texas Instruments Central Research Laboratories as a Member of Technical Staff (MTS) in the Materials Characterization Branch of the Materials Science Laboratory, and was elected a Senior MTS in 1996 for his contributions. Dr. Wallace was then appointed in 1997 to manage the Advanced Technology branch that focused on advanced device concepts and the associated material integration issues, including high-k dielectrics.
In 2003, he joined the faculty in the Erik Jonson School of Engineering and Computer Science at the University of Texas at Dallas as a Professor of Electrical Engineering and Physics, and is the director of the Nanoelectronic Materials and the Clean Room Research Laboratories.
He has authored or co-authored over 140 publications in peer reviewed journals and proceedings, as well as 70 US and international patents. Among these, he is also a co-inventor of the Hf-based high-k gate dielectric materials used in transistor production by the semiconductor industry for the 45 nm node.
A review published in the Journal of Applied Physics on high-k gate dielectrics which he coauthored was recognized by the Semiconductor Research Corporation as one of the most influential research publications in the field with more than 2500 citations to date according to the Scopus database, and was selected in 2006 to be among the 45 top cited publications by the American Institute of Physics over the last 75 years.
He was named Fellow of the AVS (2007) and IEEE (2009) for his contributions to the field of high-k dielectrics. He is a member of the Applied Surface Science and the Electronic Materials and Processing divisions in the AVS, a member of the Electron Device Society in IEEE, and a member of the Materials Research Society and the Electrochemical Society.
Minjoo Larry Lee
Electrical Engineering
Yale University
“Solar Cells”
Abstract
Unlike traditional semiconductor products, solar cells are made from a surprisingly wide variety of compounds and alloys ranging from I-III-VI chalcopyrites to amorphous Si. The performance limits of solar cells are dictated both by intrinsic materials properties arising from the nature of their atomic bonds (e.g. indirect vs direct bandgap, absorption coefficient) and by extrinsic materials properties arising from their defects (e.g. minority carrier lifetime, surface recombination velocity). In this tutorial, I will first show a process by which limiting solar cell efficiencies for single junction cells can be estimated for a given spectrum and bandgap. The results of these computations closely match the Shockley-Queisser limits while placing greater emphasis on device physics and allowing extension to multi-junction cells. Next, I will discuss the main solar cell materials being developed today (CdTe, CIGS, III-V, crystalline-Si, and amorphous Si), giving some background on why each of these materials are of interest and the challenges each one presents. I will also show how the disparate properties of solar cell materials lead to widely varying solar cell designs and materials deposition techniques. Finally, I will conclude by discussing materials concepts and recent results on III-V lattice-mismatched, multi-junction solar cells. Such cells hold the record for solar cell efficiency (41.1%), and we will discuss pathways to achieving 50% efficiency and higher.
Short Bio
Minjoo Larry Lee received his Sc.B. with honors in materials science and engineering from Brown University, Providence, RI, in 1998 and his Ph.D. in electronic materials from the Massachusetts Institute of Technology (MIT), Cambridge, MA in 2003. From 2003 to 2006, he was a Postdoctoral Researcher with the Microsystems Technology Laboratory and the Department of Materials Science and Engineering at MIT. From 2006-2007, he was with the Center for Thermoelectrics Research at Research Triangle Institute in Durham, NC, and in 2008 he joined Yale University in New Haven, CT as an assistant professor of electrical engineering. He is the author or coauthor of over 60 technical papers and refereed conference proceedings and holds five patents. His primary research interests include lattice-mismatched heteroepitaxy of III-V and group-IV materials, self-assembled nanostructures, high- mobility transistors, and multi-junction solar cells. Dr. Lee is a member of the Minerals, Metals and Materials Society (TMS), the Materials Research Society (MRS), and the IEEE. In 2003, he won an MRS gold award for graduate student research, and in 2005, he was a recipient of the IEEE George E. Smith award.