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R. G. Herb Condensed Matter Seminar
Quantum Effects in Transport Through Semiconductor Nanocrystals and Their Ensembles
Date: Monday, August 26th
Time: 10:00 am
Place: 5280 Chamberlin
Speaker: Omri Wolf, Racah Institute of Physics, The Hebrew University of Jerusalem
Abstract: Semiconductor nanocrystals (NCs) are very promising for use in electronic and opto-electronic applications. This arises from quantum confinement effects that give an additional parameter for tuning their electrical transport and optical properties. In order to use this "knob" effectively, extensive studies must be carried out both on single particles and on their ensembles.

I will present several experiments aimed at revealing quantum effects via transport measurements through several types of NCs. First, I will show that colloidal CdSe and CdS nanorods can be used as single electron charge sensors due to induced current switching. Second, I will demonstrate that surface recombination has a profound, size-dependent, effect on the photo-transport through Si-NCs ensembles. Finally, I will present a systematic scanning tunneling spectroscopy study of size and surface-chemistry effects on the electronic level structure of Si-NCs. The tunneling spectra clearly exhibit the quantum confinement effect even in (surface-ligand dependent) cases where these are not manifested in the optical spectra. In addition, the spectra show a p-type surface doping effect in nitrogen terminated Si-NCs.
Host: Eriksson
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