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Proceedings Paper

Semiconductor nanoplatelets: a new colloidal system for low-threshold high-gain stimulated emission (Presentation Recording)
Author(s): Matthew A. Pelton; Chunxing She; Igor Fedin; Dmitriy Dolzhnikov; Sandrine Ithurria; Erfan Baghani; Stephen K. O'Leary; Arnaud Demortiere; Richard D. Schaller; Dmitri V. Talapin
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Paper Abstract

Quantum wells (QWs) are thin semiconductor layers than confine electrons and holes in one dimension. They are widely used for optoelectronic devices, particularly semiconductor lasers, but have so far been produced using expensive epitaxial crystal-growth techniques. This has motivated research into the use of colloidal semiconductor nanocrystals, which can be synthesized chemically at low cost, and can be processed in the solution phase. However, initial demonstrations of optical gain from colloidal nanocrystals involved high thresholds. Recently, colloidal synthesis methods have been developed for the production of thin, atomically flat semiconductor nanocrystals, known as nanoplatelets (NPLs). We investigated relaxation of high-energy carriers in colloidal CdSe NPLs, and found that the relaxation is characteristic of a QW system. Carrier cooling and relaxation on time scales from picoseconds to hundreds of picoseconds are dominated by Auger-type exciton-exciton interactions. The picosecond-scale cooling of hot carriers is much faster than the exciton recombination rate, as required for use of these NPLs as optical gain and lasing materials. We therefore investigated amplified spontaneous emission using close-packed films of NPLs. We observed thresholds that were more than 4 times lower than the best reported value for colloidal nanocrystals. Moreover, gain in these films is 4 times higher than gain reported for other colloidal nanocrystals, and saturates at pump fluences more than two orders of magnitude above the ASE threshold. We attribute this exceptional performance to large optical cross-sections, relatively slow Auger recombination rates, and narrow ensemble emission linewidths.

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9545, Nanophotonic Materials XII, 954503 (5 October 2015); doi: 10.1117/12.2186667
Show Author Affiliations
Matthew A. Pelton, Univ. of Maryland, Baltimore County (United States)
Argonne National Lab. (United States)
Chunxing She, The Univ. of Chicago (United States)
Igor Fedin, The Univ. of Chicago (United States)
Dmitriy Dolzhnikov, The Univ. of Chicago (United States)
Sandrine Ithurria, The Univ. of Chicago (United States)
Erfan Baghani, The Univ. of British Columbia (Canada)
Stephen K. O'Leary, The Univ. of British Columbia (Canada)
Arnaud Demortiere, Illinois Institute of Technology (United States)
Richard D. Schaller, Argonne National Lab. (United States)
Dmitri V. Talapin, The Univ. of Chicago (United States)
Argonne National Lab. (United States)

Published in SPIE Proceedings Vol. 9545:
Nanophotonic Materials XII
Stefano Cabrini; Gilles Lérondel; Adam M. Schwartzberg; Taleb Mokari, Editor(s)

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