Brian A. Korgel
Semiconductor Nanowires
Department of Chemical Engineering,
Texas Materials Institute,
Center for Nano- and Molecular Science and Technology
The University of Texas at Austin
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.
Biography:
Brian A. Korgel is Associate Professor and Frank A. Liddell, Jr. Centennial Fellow in Chemical Engineering at the University of Texas at Austin. He received his BS (1991) and Ph.D. (1997) degrees in Chemical Engineering from UCLA and was a post-doctoral fellow in the Department of Chemistry at University College Dublin, Ireland until joining the faculty at UT Austin in July, 1998. His research is in the area of nanomaterials chemistry, developing new routes to nanocrystal and nanowire synthesis and assembly. At UT Austin, he serves as Associate Director of the Center for Nano- and Molecular Science and Technology (CNM) and founded and currently directs the Ph.D. Portfolio Program in Nanoscience and Nanotechnology. He has published over 95 peer-reviewed papers in journals such as Science, Physical Review Letters, the Journal of the American Chemical Society and Angewandte Chemie and holds 4 patents. He has been one of the top-20 most highly cited chemical engineers during the past five years, and his paper in Science on silicon nanowire synthesis is the second-highest cited paper written by a chemical engineer since 2000. He currently serves as Associate Editor for the Journal of Crystal Growth and is a member of the Editorial Advisory Board of the ACS journal, Chemistry of Materials. In 2002, he founded the company InnovaLight to develop silicon nanocrystal applications and served on their Board of Directors until this year.
