Probing Charge Dynamics in Nano-materials with Nano-tools

Date: 
Friday, January 24, 2014 - 3:00pm
Location: 
McDonnell Douglas Engineering Auditorium

ChEMS Seminar

Dr. Tamar Mentzel
Postdoctoral Research Fellow, Department of Physics
University of California, Berkeley


By manipulating matter at the nanoscale, we can make new materials (nano-materials) tailored to have desired—and even unconventional--properties, and new measurement tools (nano-tools) with higher sensitivity and precision than any macroscopic tool.  In the first portion of my talk, I will discuss one of the simplest examples of a nanomaterial, a lattice of nanocrystals.  One challenge in creating nanocrystal solids with desirable properties is to assemble the nanocrystals with sufficient order. For example, until recently, the electronic properties of nanocrystals were dominated by disorder, and their assembly was not controlled adequately for them to be components of nanoscale circuits.  I will discuss a novel technique, based on e-beam lithography, for assembling nanocrystal solids with sufficient precision and order to be integrated into nanoscale electronic and optoelectronic devices. Eliminating structural defects in nanocrystals is an essential step toward realizing and exploiting their predicted unconventional charge and spin transport properties, which are key for application in quantum computing and spintronics.  In the second portion of my talk, I will present a novel nano-tool for measuring charge in nanoscale structures.  Measuring electrical properties of nanoscale devices is often complicated by the small contact area between the device and the measurement electrodes: The contacts can be unstable or add series resistance.  Our nanoscale charge sensor eliminates contact effects.  The nanoscale sensor enables a highly sensitive measurement that can detect the motion of a single charge.  In turn, that makes it possible to measure electrical conductances as small as 10^-20 Siemens by applying only one volt bias. This is approximately six orders of magnitude more precise than state-of-the-art current-based measurements permit.
 

Bio: Tamar Mentzel is UC Berkeley Chancellor’s Postdoctoral Research Fellow in the Department of Physics. Her research focuses on nanostructured semiconductor materials. She holds patents for optoelectronic devices made of semiconductor nanocrystals and for a technique for measuring electrical conductance in extremely resistive materials. She made the first electrically conductive, nanopatterned films of semiconductor nanocrystals.  She received her BS from Yale University and her PhD from Harvard University and was a postdoc at MIT.