Science / Technology - Colloquium
Monday, November 2, 2009
4:00 PM-5:00 PM
Olin Hall
223
The new "EXX" phenomena in macroscopic, microscopic and nanoscopic metal-semiconductor hybrid structures will be described. Here E = extraordinary and XX = magnetoresistance (EMR), piezoconductance (EPC), optoconductance (EOC), and electroconductance (EEC). This new class of phenomena is based on the control and dominance of the geometric contributions, e.g. sample shape, lead placement, the presence of inhomogenieties, etc., to the transport properties of a physical system in contrast to traditional transport phenomena which are dominated by the intrinsic properties, e.g. mobility, carrier density, band structure, etc. The underlying phyiscs of EXX phenomena will be elucidated with particular emphasis on the use of analytic and finite element analysis methods to quantitatively account for the observed EXX signal enhancement. Surprising new aspects of the mesoscopic physics of the nano-hybrid structures will be addressed. A recently discovered inverse EOC (I-EOC) effect in which, nanoscopic devices (dimensions < 500 nm) show a decrease in conductivity with increased illumination intensity with an I-EOC ~ 1000% and a specific detectivity as high as D* = 3.2_1011 cmHz/W in a 250 nm device will be reported. It will be shown that I-EOC can be attributed to optical switching induced by the transition from ballistic to diffusive transport. The use of individual EXX sensors and EXX nano arrays to study, with ultrahigh spatial and temporal resolution, biologically relevant properties of cells such as surface charge density measured with a fluid-gated EEC device will be described.
Cost: FREE
Sponsored by: WPI Physics Department, Dr. Erkan Tuzel
Suggested Audiences: College
E-mail:
tuzel@wpi.edu
Phone: 508-831-5391
Last Modified: September 22, 2009 at 3:21 PM
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