|Posted on October 20, 2015 at 3:00 PM|
Semiconducting quantum dots (QDs) can be found in a wide range of commercial applications, including optoelectronic, thermoelectric, and energy generation technologies. The electrical conductivity of QDs can be improved by adding other elements that can provide extra electrons (doping) - however, locating where these extra electrons physically locate within QDs is difficult to do at the nanoscale.
Ms. Jenna Walrath is a doctoral student in the research group led by Rachel Goldman, a professor of Material Science and Engineering. Goldman is an associate director of applied physics, and the education director for the Center for Photonic and Multiscale Nanomaterials at the University of Michigan, Ann Arbor. They recently demonstrated that such measurements might be possible. In an article published in Applied Physics Letters on May 11th, 2015, they used scanning thermoelectric microscopy to measure the thermoelectric voltage between the tip of of the microscope and a QD. Since thermoelectric voltage is correlated with the number of extra electrons, it allowed them to find those extra electrons. Such a measurement is unprecedented, and can be applied for other nanostructures, such as quantum wells and nanowires.
Prof. Goldman is a fellow of the American Vacuum Society and American Physical Society. She currently serves as an associate editor for the Journal of Electronic Materials and as a member of the editorial board for MRS News. Ms. Jenna Walrath is a PhD Candidate in Physics at the University of Michigan; she was awarded a prestigious NSF graduate research fellowship in 2013.
- Written by Eugene Choi, Edited by Paulette Clancy
(Photo credit: Provided by and used with permission from Jenna Walrath).