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Ultrafast optical microscopy on single semiconductor nanowires
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Paper Abstract

Ultrafast optical microscopy (UOM) combines a typical optical microscope and femtosecond (fs) lasers that produce high intensity, ultrashort pulses at high repetition rates over a broad wavelength range. This enables us new types of imaging modalities, including scanning optical pump-probe microscopy, which varies the pump and probe positions relatively on the sample and ultrafast optical wide field microscopy, which is capable of rapidly acquiring wide field images at different time delays, that is measurable nearly any sample in a non-contact manner with high spatial and temporal resolution simultaneously. We directly tracked carriers in space and time throughout a NW by varying the focused position of a strong optical “pump” pulse along the Si core-shell nanowires (NWs) axis while probing the resulting changes in carrier density with a weaker “probe” pulse at one end of the NW. The resulting time-dependent dynamics reveals the influence of oxide layer encapsulation on surface state passivation in core-shell NWs, as well as the presence of strong acoustic phonon oscillations, observed here for the first time in single NWs. Time-resolved wide field images of the photoinduced changes in transmission for a patterned semiconductor thin film and a single silicon nanowire after optical excitation are also captured in real time using a two dimensional smart pixel array detector. Our experiments enable us to extract several fundamental parameters in these samples, including the diffusion current, surface recombination velocity, diffusion coefficients, and diffusion velocities, without the influence of contacts.

Paper Details

Date Published: 7 March 2014
PDF: 6 pages
Proc. SPIE 8984, Ultrafast Phenomena and Nanophotonics XVIII, 89840U (7 March 2014); doi: 10.1117/12.2035332
Show Author Affiliations
Minah Seo, Los Alamos National Lab. (United States)
Korea Institute of Science and Technology (Korea, Republic of)
Jinkyoung Yoo, Los Alamos National Lab. (United States)
Shadi A. Dayeh, Los Alamos National Lab. (United States)
Samuel T. Picraux, Los Alamos National Lab. (United States)
Antoinette J. Taylor, Los Alamos National Lab. (United States)
Rohit P. Prasankumar, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 8984:
Ultrafast Phenomena and Nanophotonics XVIII
Markus Betz; Abdulhakem Y. Elezzabi; Jin-Joo Song; Kong-Thon Tsen, Editor(s)

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