Tuesday, August 11, 2015, 2:00 pm — CFN, Bldg. 735, Conference Rm. A - 1st fl.
Center for Functional Nanomaterials Seminar Photoresponses in Vanadium Dioxide Nanowires Prof. Hanwei Gao Department of Physics, Florida State University Tuesday, August 11, 2015 2:00 p.m. Bldg. 735 â€" Conf. Rm. A, 1st floor Abstract: Vanadium dioxide (VO2) has drawn much attention for its unique metal-insulator transition near the room temperature. The high electrical resistivity below the transition temperature (about 64 °C) is a result of the strong electron-electron correlation. Such interactions can potentially lead to remarkable charge carrier multiplication under optical excitation, a process desirable for efficient optoelectronics and photovoltaics. However, because the resistivity is highly temperature-dependent, the observed light-induced conductivity in VO2 was often attributed to photothermal effects. By varying the chopping frequency of the optical illumination, we have distinguished the photothermal and photoconductive effects in VO2 nanowires. The frequency dependent measurements indicated that the relatively slow photothermal processes can be well suppressed with high chopping frequency, whereas the fast photo-excitation of charge carrier results in a frequency-independent photoconductivity in VO2. Resolving these coexisting processes paves the way for further studies of carrier dynamics under optical excitations in strong electron correlated materials. . Host: Mingzhao Liu Joann Tesoriero Center for Functional Nanomaterials P.O. Box 5000 Upton, NY 11973 Tel. (631) 344-7791 Tax: (631) 344-3093 Tesoriero@bnl.gov
Hosted by: Mingzhao Liu
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