Three-photon excited band edge and trap emission of CdS semiconductor nanocrystals

J.W.M. Chon, M. Gu, Craig Bullen, P. Mulvaney

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We report on three-photon excited band edge and trap emission of CdS semiconductor nanocrystals. While the band edge emission intensity clearly shows a cubic dependence on excitation intensity, demonstrating three-photon absorption process, the trap emission does not exhibit such a cubic dependence. A simple theoretical model based on the assumption that there exist a limited number of trap states in nanocrystals shows good agreement with the experiment, suggesting that the number of trap states play an important role in their emission intensity dependence of multiphoton excitation. The three-photon absorption cross section of CdS nanocrystals is measured to be similar to10(-79) cm(6) s(2) photon(-2), which is three to four orders of magnitude higher than those of the previously reported common UV fluorescent dyes. (C) 2004 American Institute of Physics.
Original languageEnglish
Pages (from-to)4472-4474
JournalApplied Physics Letters
Issue number22
Publication statusPublished - 2004


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