13-19 June 2015
University of Alberta
America/Edmonton timezone
Welcome to the 2015 CAP Congress! / Bienvenue au congrès de l'ACP 2015!

Ultrafast All-Optical Switching in Semiconductor Nanoparticles

17 Jun 2015, 19:06
2m
CCIS Ground Floor PCL lounge (University of Alberta)

CCIS Ground Floor PCL lounge

University of Alberta

Poster (Student, In Competition) / Affiche (Étudiant(e), inscrit à la compétition) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM) DCMMP Poster Session with beer / Session d'affiches, avec bière DPMCM

Speaker

Jeff Krupa (University of British Columbia)

Description

Ultrafast all-optical switching offers great benefit to communication technologies, as all-optical logic operations can be performed at tremendous (terabit-per-second) data rates. Semiconductors are an obvious choice to perform such switching, given their strong optical nonlinearity, but standard bulk semiconductors suffer from relatively slow recombination—often with nanosecond or microsecond charge-carrier lifetimes. These are unfavorable material characteristics aspects for ultrafast all-optical switching, as the slow recovery impedes the ultimate data rate. To address the demands of ultrafast all-optical switching, the work put forward here investigates semiconductor nanoparticles as a material for ultrafast photoexcitation and recombination. Composite materials comprised of semiconductor nanoparticles in a polymer host are fabricated and investigated. Semiconductor nanoparticles of Si and SiC are employed, with average particle diameters of 20 nm and 50 nm, respectively. An ultrafast pulsed laser system, with 100 fs optical pulses, is used to carry out pump-probe spectroscopy on these materials. For Si, it is found that the photoexcited charge-carriers undergo recombination with a lifetime of 12 ps (being on the order of one thousand times shorter than the 20 ns bulk lifetime). For SiC, it is found that the photoexcited charge-carriers undergo recombination with a lifetime of 2.5 ps (being on the order of one million times shorter than the 22 µs bulk lifetime). A theoretical model is developed to interpret the experimental findings. The model characterizes the ultrafast charge-carrier dynamics within the nanoparticles according to diffusion and recombination processes. It is found that the increased surface-to-volume ratio of the nanoparticles promotes surface recombination, over a picosecond timescale, and this leads to the observed short charge-carrier lifetimes. The enhanced recovery times seen in these materials can be beneficial for future implementations of ultrafast all-optical switching.

Primary author

Jeff Krupa (University of British Columbia)

Co-authors

Mr Brandon Born (University of British Columbia) Mr Christopher M. Collier (University of British Columbia) Dr Jonathan F. Holzman (University of British Columbia) Mr Simon Geoffrey-Gagnon (University of British Columbia)

Presentation Materials

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