excitonics seminar series
Semiconductor nanowires: from LEDs to Solar Cells
May 4 , 2010
Haus Room - 36-428
3:00 - 4:00pm
Nanostructured materials – including nanowires, nanotubes, and nanocrystals – have unique and size-tunable properties that depend on the precise arrangement of their atomic constituents. These nanomaterials offer solutions to some of the current challenges in science and engineering, and could potentially lead to improved understanding of the physical world and to discoveries of new phenomena. However, functionality of novel nanomaterials and their impact on society will be ultimately dictated by our understanding and ability to precisely control their structural properties, size uniformity, and dopant distribution at the atomic level.
In this talk, I will discuss the growth, doping, and applications of III-V nanowires and nanowire heterostructures using metalorganic chemical vapor deposition, as well as advanced electron microscopy techniques for direct correlation of structural and physical properties with high spatial resolution. We have demonstrated that the cathodoluminescence (CL) technique, coupled with scanning transmission electron microscopy (STEM), effectively bypasses the resolution limit of conventional far-field photoluminescence spectroscopy and allows direct structure-property correlation on the nanoscale. The CL-STEM optical studies of single nanowire heterostructures with spatial resolution of <20 nm will be discussed. Finally, applications of semiconductor nanowires for LED and solar cell applications will be described.
Silvija Gradečak is an Assistant Professor of Materials Science and Engineering at MIT. She received her Dipl. Ing. degree in Physics from University of Zagreb, Croatia, in 1999 and her PhD in Physics from EPFL, Switzerland, in 2003. Following two years of postdoctoral research at Harvard University with Prof. Charles Lieber, Gradečak joined the faculty at MIT in 2006. Prof. Gradečak’s group at MIT uses interdisciplinary approach to study semiconductor materials and low-dimensional systems. She held the Merton C. Flemings Career Development Chair and is a recipient of the NSF CAREER Award and 3M Innovation Award.