This talk focuses on two types of nanotechnology building blocks and their applications: III-V semiconductor nanotubes (SNTs) and nanowires (NWs).

SNT is an emerging field that has only caught limited attention, yet possesses the potential to provide a wide range of functionalities. It is formed by a combination of top-down and bottom-up approach through the self-rolling of strained thin films. This allows feasible large area assembly and integration with existing semiconductor technology, while maintaining the control of tube size and heterojunction formation in the tube wall. In the first part of the talk, I will discuss the formation mechanism, large area assembly and dispersion of InxGa1-xAs/GaAs SNTs, and optical characterization of quantum well structures embedded in the wall of the tubes.

Interest in semiconductor NWs have increased exponentially over the past several years because of their unique optical and electrical properties and the capability of producing high quality heterostructures with large lattice mismatch on the nanometer scale. Integration of semiconductor nanowire based devices has been problematic and usually requires the technologically disadvantageous (111) substrate for vertical nanowire devices or ex-situ assembly techniques to align planar nanowire devices. In the second part of the talk, I will present our discovery of a type of NWs that are nearly twin-defect free, high carrier mobility, self-aligned, and transfer-printable. Output and transfer characteristics of MESFET using such GaAs nanowire as the channel material will be analyzed.

Biography: Xiuling Li received her Ph.D. degree in Chemistry from the University of California at Los Angeles. She joined the faculty of the University of Illinois in 2007, after working at a startup company for six years. She is currently an assistant professor in the Department of Electrical and Computer Engineering, and an affiliate faculty member of the the Beckman Institute and the Department of Materials Science and Engineering. Her current research interests are in the area of nanostructured semiconductor materials and devices. She has recently won the NSF CAREER award.  Her group's work on the planar nanowires has won one of the best student paper awards at the 2008 IEEE LEOS annual meeting. The micro and nanotube work has been identified as an outstanding symposium paper presented at the 2008 MRS Fall meeting.  Xiuling Li, Univ. of Illinois-Website

Host:  Eric Garfunkel