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| Multiphase Gallilum Nitride Nanowires and Nanocircuits | |
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| Description: | Nano 501 Tutorial
Virginia Ayres, Michigan State University ABSTRACT Catalyst-free vapor-solid nanowire growth, a newly described method for the production of nanowires compatible with a wide variety of semiconductor materials, has been used to produce novel multiphase zinc-blende/wurtzite gallium nitride nanowires. Orientation relation-ships within the multiphase nanowire were observed using high-resolution transmission electron microscopy of cross-sections created with focused ion beam techniques. A totally coherent interface be-tween the zinc blende and wurtzite phases, which is sustained over the entire length of the nanowire, is identified and discussed. Multiphase nanowire growth occurs at specific nanoscale nucleation sites on platelets of gallium nitride. Furnace growth temperature has been shown to exert a strong influence on nucleation site formation. The types of nanowires that form and the corresponding nanowire nucleation sites over the furnace growth temperature range 850-1000°C are discussed. Multiphase nanowires may have novel properties that augment and may be superior to single-phase nanowires in device applications. The electronic performance of the new multiphase nanowires in a NanoFET configuration is investigated using 2-point and 4-point probe current-voltage characterizations. The current-voltage characterizations were carried in a special nano-probing system, in which oxide sharpened ~30 nm radius tungsten nanoprobes were coupled to directly a nanowire while the experiments were directly visualized using a scanning electron microscope. All measurements showed high current densities. Evidence for single-phase current transport within the multiphase nanowire structure is discussed. Novel multiphase gallium nitride nanowires and nano-circuits may provide unique flexibility for photon and carrier confinement. *with collaborators: B.W. Jacobs, K. McElroy, M.A. Crimp, Michigan State University; J.B. Halpern, and M-Q. He, Howard University; H.C. Shaw, NASA Goddard Space Flight Center; M.P. Petkov, NASA Jet Propulsion Laboratory. BIO Virginia M. Ayres is an Associate Professor in the Department of Electrical & Computer Engineering, and heads the Electronic and Biological Nano-structures Laboratory (http://www.egr.msu.edu/ebnl) at Michigan State University. Her research interests include the reduced dimensionality-based electronic properties of nanotubes and nanowires. Dr. Ayres earned her Ph.D. and M.S. in Physics from Purdue University, and her B.A. in Physics and Biophysics from the Johns Hopkins University. She is the recipient of two NASA Faculty Fellowship Awards and of two international awards from the Japan Society for Promotion of Science and from Tokyo Institute of Technology for research and education in Japan. In 2006, she was honored with an Outstanding Alumnus Award from the Department of Physics at Purdue University. |
| When: |
Wednesday, January 16 2008, 2:30pm - 3:30pm |
| Where: | Purdue University, EE 317 |
| Submitted by: Alicia Goodman | |