Photo assisted acids dissolution of Si nanocrystals

ANYL 103

Jonghoon Choi, jongchoi@nist.gov, Department of Chemical and Biomolecular engineering, University of Maryland, College Park, MD 20742, Nam Sun Wang, nsw@eng.umd.edu, Department of Chemical Engineering, University of Maryland, College Park, 20742, and Vytautas Reipa, vytas@nist.gov, Biochemical Science Division, National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, MD 20899.
We demonstrate that the photo-assisted dissolution of Si nanocrystals with an HF/HNO3 acid mixture promotes the spectral blue shift of photoluminescence. Specifically, Si nanocrystals were first synthesized from the anodic etching of Si wafers and mechanical stripping of the porous surface layer from the etched wafers. The subsequent UV-assisted dissolution reaction generated samples that progressed with time from red, to orange, yellow, and green photoluminescence, which indicates a progressive shrinkage in the nanoparticle size. The resulting fluorescent Si nanocrystals during the dissolution process were characterized with photoluminescence spectroscopy, TEM, absorption spectroscopy, and time resolved fluorescence spectroscopy. Decay time measurements hinted that blue Si nanocrystals undergo a different fluorescence emission mechanism from those emitting at other visible wavelengths. Our Si nanocrystals possess high quantum efficiency (10-40%) and cover the entire visible spectrum. These unique properties make them an ideal fluorescent dye in biological applications.
 

General Papers
7:00 PM-9:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster

Division of Analytical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006