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Proceedings Paper

Investigation of ultrafast carrier dynamics in ZnO rods using two-photon emission and second harmonic generation microscopy
Author(s): Ralph L. House; Brian P. Mehl; Chuan Zhang; Justin R. Kirschbrown; Scott C. Barnes; John M. Papanikolas
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Paper Abstract

The demand for novel optoelectronic and photonic technologies has fueled an intense research effort to synthesize and characterize nanostructured semiconductor materials with unique properties that lend themselves to technological innovation. Zinc Oxide has emerged as an attractive candidate for a variety of applications, due in part to a large second order nonlinear susceptibility, its wide band-gap and large exciton binding energy. We have used time-resolved nonlinear two-photon emission and second harmonic generation microscopy to characterize the optical properties and excited state dynamics of individual rods. Ultrafast emission microscopy is used to follow the trapping dynamics of photoexcited charge carriers. Our results show a time-dependent red-shift in the trap emission band that is interpreted as arising from carrier percolation through trap states. In a second series of experiments, second harmonic generation (SHG) microscopy illustrates the connection between the optical mode structure of the object and its nonlinear mixing efficiency. Images show a periodic modulation in the SHG efficiency that is symmetrically situated relative to the rod midpoint. This phenomenon arises when the fundamental optical field couples into standing wave resonator modes of the structure and is a direct manifestation of the tapered shape of the rod.

Paper Details

Date Published: 21 August 2009
PDF: 11 pages
Proc. SPIE 7396, Physical Chemistry of Interfaces and Nanomaterials VIII, 73960G (21 August 2009); doi: 10.1117/12.826064
Show Author Affiliations
Ralph L. House, The Univ. of North Carolina at Chapel Hill (United States)
Brian P. Mehl, The Univ. of North Carolina at Chapel Hill (United States)
Chuan Zhang, The Univ. of North Carolina at Chapel Hill (United States)
Justin R. Kirschbrown, The Univ. of North Carolina at Chapel Hill (United States)
Scott C. Barnes, The Univ. of North Carolina at Chapel Hill (United States)
John M. Papanikolas, The Univ. of North Carolina at Chapel Hill (United States)


Published in SPIE Proceedings Vol. 7396:
Physical Chemistry of Interfaces and Nanomaterials VIII
Oliver L. A. Monti; Oleg V. Prezhdo, Editor(s)

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