October 6, 2014
Speaker: Paul R. Berger, Professor, Department of Electrical and Computer Engineering/Department of Physics, Ohio State University
Quantum functional circuitry exploiting negative differential resistance (NDR) devices offers a paradigm shift in computational architectures for a multitude of circuitries (low-power embedded memory, mixed-signal and logic), that enables continued Si/SiGe scaling according to Moore’s Law. The advantage of quantum functional circuits is illustrated by the N-shaped electrical characteristics of two serially connected NDR devices which can be exploited to easily fashion two stable latching points. The requirement of an NDR device for these circuit topologies is room temperature NDR operation with a reasonably high peak-to-valley current ratio (PVCR) [≥ 3]. NDR-based circuitry facilitates simple circuit topologies to fashion latches etc., permitting tunnel diode/transistor circuits that require fewer devices, less chip area and reduced power consumption. Already, preliminary work has demonstrated tunnel diode static random access memory (TSRAM) that operates below 0.5 volts and only requires a 0.3 voltage swing! TSRAM is DRAM-like in its configuration and chip area footprint, but it is refresh-free, thus providing greater benefits beyond low-voltage operation. Multi-level logic circuits are also readily enabled, and provide further opportunities.
We will present results on room temperature NDR devices and circuits using a Si-based resonant interband tunnel diode (RITD) developed by this team is a that is a hybrid NDR device that uses quantum wells formed by delta-doping and appropriate band offsets to facilitate robust tunneling across a p-n junction. This will illustrate this pathway, and then this will be extended to conjugated polymer based devices that are in their initial investigations.
The polymer device to be presented leverages the unique flexible and solution-processable properties of conjugated polymer semiconductors. We will demonstrate robust room temperature negative differential resistance and logic circuit operations using polymer tunnel diodes (ITO/TiO2/MEH-PPV/Al), suitable for SmartCard topologies.
Paul R. Berger is a Professor in Electrical & Computer Engineering at Ohio State University and Physics (by Courtesy). He received the B.S.E. in engineering physics, and the M.S.E. and Ph.D. (1990) in electrical engineering, respectively, all from the University of Michigan, Ann Arbor. Currently, Dr. Berger is actively working on conjugated polymer-based optoelectronic and electronic devices; molecular electronics; Si/SiGe nanoelectronic devices and fabrication processes; Si-based resonant interband tunneling diodes and quantum functional circuitry; bioelectronics; and semiconductor materials, fabrication and growth.
Formerly, he worked at Bell Laboratories, Murray Hill, NJ (1990-’92) and taught at the University of Delaware in Electrical and Computer Engineering (1992-2000). In 1999, Prof. Berger took a sabbatical leave while working first at the Max-Planck Institute for Polymer Research, Mainz, Germany while supported by Prof. Dr. Gerhard Wegner and then moved on to Cambridge Display Technology, Ltd., Cambridge, United Kingdom working under Dr. Jeremy Burroughes. In 2008, Prof. Berger spent an extended sabbatical leave at IMEC (Interuniversity Microelectronics Center) in Leuven, Belgium while appointed as a Visiting Professor in the Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Belgium.
He has authored ~100 articles, 5 book sections and been issued 17 patents with 5 more pending from 50+ disclosures. Some notable recognitions for Dr. Berger were an NSF CAREER Award (1996), a DARPA ULTRA Sustained Excellence Award (1998), a Lumley Research Award (2006, 2011), and a Faculty Diversity Excellence Award (2009). In 2014, he was awarded the “Outstanding Engineering Educator”, representing the entire State of Ohio, by the Ohio Society of Professional Engineers. He has been on the Program and Advisory Committees of numerous conferences, including the IEDM, ISDRS meetings. He currently is the Chair of the Columbus IEEE EDS/Photonics Chapter and Faculty Advisor to Ohio State’s IEEE Student Chapters. He is a Fellow and Distinguished Lecturer of IEEE EDS and a Senior member of Optical Society of America.