Brongersma, M. L. and Polman, A. and Min, K. S. and Boer, E. and Tambo, T. and Atwater, H. A. (1998) Tuning the emission wavelength of Si nanocrystals in SiO2 by oxidation. Applied Physics Letters, 72 (20). pp. 2577-2579. ISSN 0003-6951 http://resolver.caltech.edu/CaltechAUTHORS:BROapl98
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Si nanocrystals (diameter 2–5 nm) were formed by 35 keV Si + implantation at a fluence of 6 × 1016 Si/cm2 into a 100 nm thick thermally grown SiO2 film on Si (100), followed by thermal annealing at 1100 °C for 10 min. The nanocrystals show a broad photoluminescence spectrum, peaking at 880 nm, attributed to the recombination of quantum confined excitons. Rutherford backscattering spectrometry and transmission electron microscopy show that annealing these samples in flowing O2 at 1000 °C for times up to 30 min results in oxidation of the Si nanocrystals, first close to the SiO2 film surface and later at greater depths. Upon oxidation for 30 min the photoluminescence peak wavelength blueshifts by more than 200 nm. This blueshift is attributed to a quantum size effect in which a reduction of the average nanocrystal size leads to emission at shorter wavelengths. The room temperature luminescence lifetime measured at 700 nm increases from 12 µs for the unoxidized film to 43 µs for the film that was oxidized for 29 min.
|Additional Information:||©1998 American Institute of Physics. (Received 6 October 1997; accepted 17 March 1998) The work at FOM was financially supported by NWO, STW, and the SCOOP program of the European Union. Further support was obtained from the U.S. Department of Energy under Grant No. DE-FG03-89ER45395 and the NATO Ministry for Scientific Affairs.|
|Subject Keywords:||SILICON OXIDES; SILICON; OXIDATION; ION IMPLANTATION; PHOTOLUMINESCENCE; RECOMBINATION; RUTHERFORD SCATTERING; TRANSMISSION ELECTRON MICROSCOPY; silicon compounds; insulating thin films; nanostructured materials; annealing; Rutherford backscattering; excitons; spectral line shift; radiative lifetimes|
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|Deposited On:||05 Mar 2006|
|Last Modified:||26 Dec 2012 08:47|
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