Simultaneous photocharging and luminescence intermittency in silicon nanocrystals

Rostron, R J, Chao, Yimin, Roberts, G and Horrocks, B R (2009) Simultaneous photocharging and luminescence intermittency in silicon nanocrystals. Journal of Physics: Condensed Matter, 21 (23). p. 235301. ISSN 1361-648X

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Abstract

Contemporaneous measurements of the time dependence of photoluminescence and concomitant electrical conduction in films of alkylated silicon nanocrystals (NCs) during and between periods of continuous-wave laser irradiation of arbitrary duration establish the role played by photoionization to a conducting state in the intermittent light emission from silicon nanocrystals. The luminescence and current generated by electron photoejection both decay to non-zero, steady-state values during irradiation with visible laser light at incident intensities in the range 0.25–0.30 ± 0.01 kW cm-2; on cessation of irradiation, the non-conducting photoluminescent state of the NCs is substantially regained. These observations are consistent with a model in which the decay of photoluminescence is ascribed to autoionization of the silicon NCs with a most probable lifetime Ta, depending on particle size, and recovery of luminescence to electron–hole recombination characterized by a most probable lifetime Teh. Values of Ta = 1.08 ± 0.03 s and Teh = 770 ± 300 s are extracted from nonlinear least-squares fitting to the time dependence of the photoluminescence intensity. The temporal behavior of the transient photocurrent is found to be quantitatively consistent with a one-dimensional model of diffusion of charge carriers between NCs. Integration of the time dependence of the photocurrent response coupled with an estimate of the volume irradiated with the laser light suggests ionization of one electron per NC during photon irradiation.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Rachel Smith
Date Deposited: 21 Mar 2011 12:27
Last Modified: 18 Sep 2018 15:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/26761
DOI: 10.1088/0953-8984/21/23/235301

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