Semiconductor nanostructures produced by wet chemical synthesis are extremely heterogeneous, which makes single particle techniques a useful way to interrogate their properties. In this talk the ultrafast dynamics of single CdTe nanowires will be presented. These experiments were performed by transient absorption microscopy. The wires have lengths of several microns and lateral dimensions on the order of 30 nm. The transient absorption traces show very fast decays, which are assigned to charge carrier trapping into surface defects. The time constants vary for different wires due to differences in the energetics and/or density of surface trap sites. Measurements performed at the bandedge compared to the near-IR give slightly different time constants, implying that the dynamics for electron and hole trapping are different. The rate of charge carrier trapping was observed to slow down at high carrier densities, which was attributed to trap-state filling. Modulations due to the fundamental and first overtone of the acoustic breathing mode were also observed in the transient absorption traces. The quality factors for these modes were similar to those measured for metal nanostructures, and indicate a complex interaction with the environment.References: Shun S. Lo, Todd Major, Nattasamon Petchsang, Libai Huang, Masaru Kuno and Gregory V. Hartland, �Charge Carrier Trapping and Acoustic Phonon Modes in Single CdTe Nanowires�, ACS Nano, 2012 , 6, 5274�5282.Shun Shang Lo, Todd A. Major, Mary Sajini Devadas, and Gregory V. Hartland, �Optical Detection of Single Nano-objects by Transient Absorption Microscopy�, Analyst, 2013  , 138, 25-31.

Ultrafast studies of charge carrier trapping in single semiconductor nanowires

246th National Meeting (2013)

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