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Seminars
Semiconductor Nanowires
Professor Brian A. Korgel
Department of Chemical Engineering
Texas Materials Institute
Center for Nano- and Molecular Science & Technology
The University of Texas at Austin
When: Thursday, October 26, 2006
Time: 2:30 PM to 3:30 PM
Where: 1070 Duncall Hall
Abstract:
Two general solution-phase methods for promoting nanorod and nanowire synthesis in solution have been developed: (1) metal nanocrystal-seeded nanowire synthesis and (2) a general solution-phase method for inducing CdS, CdSe, and CdTe nanorod growth by sequential precursor injection. Metal nanocrystal-seeded nanowire growth can be carried out under high temperature conditions in supercritical fluids for silicon and germanium, or in conventional solvents using low melting point metals, like Bi to seed Group III-V nanowires, such as GaAs, GaP, InAs and InP. The effect of temperature and growth conditions on nanowire synthesis and crystallographic orientation of the nanowires will be discussed. In the case of method (2), the shape of Group II-VI nanocrystals, including CdS, CdSe and CdTe can be tuned from spheres to rods with aspect ratios up to 20 simply by sequentially injecting precursor solutions to promote epitaxial elongation of the wurtzite crystal structure in the [001] direction (i.e., along the c-axis). This sequential injection approach has been applied to form both Type I (Nested) and Type II (Offset) heterostructures of CdS/CdSe/CdS and CdTe/CdSe/CdTe nanorods. These two synthetic approaches provide general methods that enable the solution-based synthesis of Group IV, Group III-V and Group II-VI semiconductor nanorods and nanowires with high reaction yield.
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