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CPM Seminar
Duncan Stewart HP Labs, Palo Alto It has been more than 25 years since Aviram and Ratner first proposed single molecule diodes, yet only recently have we been able to approach fabrication of devices that might display such single molecule properties. In the last five years published reports have claimed single-molecule rectification, negative-differential resistance and, most recently, transistor action. Hewlett-Packard Labs initiated a dedicated effort in molecular electronics three years ago. I will outline our work on architecture, defect tolerance and fabrication of nanowires by epitaxial growth, catalyzed CVD growth and imprint lithography as well as molecular efforts on ab initio modeling, monolayer film deposition and electrical device fabrication. I will also describe detailed electrical transport characterization of several planar electrode/Langmuir-Blodgett molecular monolayer/electrode systems that show generic classes of electrical switching and rectifying behaviour, independent of the molecular species. Investigations of Al/Ti, Pt/Ti and Pt/Pt devices show different generic behaviours and confirm the dominant role played by the poorly understood electrode/molecule interface. Indeed the difficulty of controlling this electrode/molecule contact has to date prevented any correlation between theory and single-molecule experiment. We have nonetheless used the monolayer switching characteristics to demonstrate memory and logic circuits, and have begun a systematic investigation of transport mechanisms in the simplest Pt/Pt electrode system.
Monday, March 4th 2002, 15:00 |