"Nonclassical tunneling and feedback-based devices for nanoelectronics" Alex Zaslavsky Friday September 19, 2014 3:30pm PHYS 203 Modern computing and, in fact, modern civilization is based on digital switching by complementary (CMOS) field effect transistors (FETs). There is a limit on how sharply the FET current can be turned off, due to thermionic injection over a voltage-controlled potential barrier. Sharper switching, which is necessary if silicon transistor downscaling is to proceed beyond the next decade, requires transistors based on alternative physical mechanisms, such as quantum mechanical tunneling or carrier injection with positive feedback. This seminar will discuss two types of nonclassical transistor-like devices: tunneling FETs (TFETs) and feedback FETs. In the TFET arena, which is currently attracting great industrial interest, we will discuss the improvement of the transistor characteristics via the use of hetero-nanowire bandgap engineering. We then discuss the proposed bipolar enhancement of the tunneling current in a monolithic silicon-compatible structure that in simulation yields the sharpest switching performance to date. In the feedback FET arena, we discuss the Z2-FET (for zero voltage and zero impact ionization) that produces very sharp switching with controlled hysteresis in the output characteristics and holds promise for very fast and compact semiconductor memory. While these alternative devices are promising, some of the basic underlying physics - e.g. interband tunneling in indirect semiconductors - is not sufficiently understood. Still, the unique characteristics deriving from quantum mechanical tunneling and feedback make such devices an interesting playground for innovative device research, as standard silicon technology heads towards the long-predicted end of the miniaturization. *In collaboration with: Son T. Le, Peng Zhang (Brown U.); Jing Wan, S. Cristoloveanu, C. Le Royer (Minatec, Grenoble); D. E. Perea, S. A. Dayeh, and S. T. Picraux (Los Alamos). Short bio: Alex Zaslavsky received his Ph.D. in electrical engineering from Princeton in 1991 and was a postdoctoral scientist at IBM Yorktown until 1993. In 1994 he joined Brown University, where he is now Professor of Engineering and Physics. He was a recipient of a Sloan Fellowship, an ONR Young Investigator award, an NSF Career award, and was a visiting senior chair of excellence at the Nanosciences Foundation of Grenoble in 2009-12. He has been an editor of the Solid State Electronics international journal since 2003. He has authored over 120 journal articles and book chapters, and co-edited eight books in the microelectronics field. Research interests include tunneling- and feedback-based semiconductor devices, ultrathin semiconductor-on-insulator structures and hetero-nanowires, amorphous-oxide-based devices, and error-immune probabilistic computing. -----------------------------------------------------------