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Size-dependent electron-hole exchange interaction in Si nanocrystals

Brongersma, M. L. and Kik, P. G. and Polman, A. and Min, K. S. and Atwater, Harry A. (2000) Size-dependent electron-hole exchange interaction in Si nanocrystals. Applied Physics Letters, 76 (3). pp. 351-353. ISSN 0003-6951. http://resolver.caltech.edu/CaltechAUTHORS:BROapl00

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Abstract

Silicon nanocrystals with diameters ranging from [approximate]2 to 5.5 nm were formed by Si ion implantation into SiO2 followed by annealing. After passivation with deuterium, the photoluminescence (PL) spectrum at 12 K peaks at 1.60 eV and has a full width at half maximum of 0.28 eV. The emission is attributed to the recombination of quantum-confined excitons in the nanocrystals. The temperature dependence of the PL intensity and decay rate at several energies between 1.4 and 1.9 eV was determined between 12 and 300 K. The temperature dependence of the radiative decay rate was determined, and is in good agreement with a model that takes into account the energy splitting between the excitonic singlet and triplet levels due to the electron-hole exchange interaction. The exchange energy splitting increases from 8.4 meV for large nanocrystals ([approximate]5.5 nm) to 16.5 meV for small nanocrystals ([approximate]2 nm). For all nanocrystal sizes, the radiative rate from the singlet state is 300–800 times larger than the radiative rate from the triplet state.


Item Type:Article
Additional Information:©2000 American Institute of Physics. (Received 4 February 1999; accepted 15 November 1999) This work is part of the research program of FOM and was supported by NWO, the Esprit program (SCOOP) of the European Union, and the National Science Foundation.
Subject Keywords:silicon; nanostructured materials; exchange interactions (electron); excitons; photoluminescence; elemental semiconductors; radiative lifetimes; size effect; electron-hole recombination; ion implantation; annealing; spectral line broadening; spectral line intensity; triplet state
Record Number:CaltechAUTHORS:BROapl00
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:BROapl00
Alternative URL:http://dx.doi.org/10.1063/1.125751
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2427
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:03 Apr 2006
Last Modified:26 Dec 2012 08:49

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