Appelbaum Lab
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Ian Appelbaum obtained his B.S. summa cum laude in Physics and Mathematics at Rensselaer Polytechnic Institute (RPI) in December 1997, and Ph.D. in Physics at the Massachusetts Institute of Technology (MIT) in June 2003. After spending one year as a postdoctoral fellow at Harvard University, he is currently an Assistant Professor of Electrical Engineering at the University of Delaware.
For several years while an undergraduate, Dr. Appelbaum worked with Prof. Ivar Giaever (Nobel laureate, 1973) at RPI. In 1996, he interned at the Los Alamos National Laboratory on quantum optics including photon state entanglement and interaction-free measurement with Paul Kwiat (now professor of Physics at U. Illinois Urbana-Champaign). In 1997, he was appointed a Summer Scholar in the CMSE/MPC program at MIT working for John Joannopoulos on simulation of near-field measurement of photonic crystal modes and was also selected for and attended the Hertz foundation-sponsored Summer Institutes in Applied Science at Lawrence Livermore National Laboratory.
As an MIT graduate student, Dr. Appelbaum conceived, developed, and experimentally demonstrated a mechanism for hot electron injection luminescence in scanning probe microscopy on buried-heterostructure light-emitting devices. This comprised of design, fabrication, and measurement of solid-state tunnel junction devices from bare semiconductor epilayers of either polarity. He also applied this luminescence mechanism to hot-electron-mediated direct optical up-conversion. Furthermore, he developed computational schemes to model hot electron transport in nanoscale semiconductor heterostructures via ballistic electron emission spectroscopy.
As a postdoctoral fellow at Harvard University under (Dean of Engineering) Prof. Venkatesh Narayanamurti, Dr. Appelbaum began work in metal/semiconductor device spintronics. He predicted and experimentally discovered the vertical hot-electron spin-valve photodiode effect which was featured on the cover of Applied Physics Letters (Nov. 3 '03), co-invented the Avalanche Spin-Valve Transistor (featured in AIP Physics News Update) and invented the Luminescent Spin Valve Transistor, a device for direct conversion of magnetic to optical information. The latter invention, an extension of his PhD work on hot electron luminescence, is the subject of an issued US patent.
More recently as a faculty member at U. Delaware, Prof. Appelbaum's group has developed novel hot electron techniques for both injection and detection of spins in semiconductors. Most notably, his group was the first to overcome significant electronic structure and materials challenges to demonstrate spin transport in Silicon, resulting in a publication in Nature. This has attracted much attention in the popular media, including Scientific American, New Scientist, MIT Technology Review, and many others. His group then showed how this device design could be used as a spin field-effect transistor both theoretically (featured on the Applied Physics Letters cover Jun 25 '07) and experimentally. His most recent accomplishment is measurement of spin transport through an entire 350-micron-thick Silicon wafer, allowing spin lifetime measurement of over 500ns at 60K, two orders of magnitude higher than any other bulk material. Ancillary methods developed for this purpose include UHV metal-film full-wafer-bonding, and the demonstration of spontaneous cohesion using single monolayer coverage of evaporated metal. Additionally, his group invented the spin-valve photo-transistor, the subject of an Applied Physics Letters cover (Jan 29 '07). His current research interests include spintronics (on which he teaches a joint undergraduate/graduate course at UD), semiconductor device carrier transport, optical up-conversion, vacuum wafer-bonding, and applications of tunneling microscopy to local hot-electron injection in metal/semiconductor devices.
Dr. Appelbaum is the author or co-author of over 30 peer-reviewed journal papers, and recipient of the National Science Foundation CAREER award (2008). He has served as a reviewer for Physical Review Letters, Physical Review B, Applied Physics Letters, etc., and a proposal reviewer for Research Corporation, the National Science Foundation, and US Department of Energy Office of Basic Energy Sciences. He has given numerous invited colloquia/seminars/symposia and is a member of Materials Research Society and a life member of the American Physical Society. He was recently chosen to be UD's 2008 Outstanding Junior Faculty Member for the College of Engineering.
