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Organizations & People
Pure Appl. Chem. Vol.
72, Nos. 1-2, pp. 245-255, 2000
Special Topic Issue on the Theme of
Effect of atmospheric oxidation on the electronic and photoluminescence
properties of silicon nanocrystal
I. N. Germanenko, M. Dongol, Y. B. Pithawalla, M. Samy El-Shall*,
and J. A. Carlisle
*Department of Chemistry and 2 Department of Physics,
Virginia Commonwealth University, Richmond, Virginia 23284 USA
Abstract: Web-like aggregates of coalesced Si nanocrystals produced
by a laser vaporization-controlled condensation technique show luminescence
properties that are similar to those of porous Si. The results are consistent
with a quantum confinement mechanism as the source of the red photoluminescence
(PL) in this system. The oxidized Si nanoparticles do not exhibit the
red PL that is characteristic of the surface-oxidized Si nanocrystals.
The nanoparticles are allowed to oxidize slowly, and the PL is measured
as a function of the exposure time in air. A significant blue shift
in the red PL peak is observed as a result of the slow oxidation process.
The dependence of quantum size effects on the bonding structure is established
by correlating the PL data with the photon-yield electronic structure
measurements made at the Advanced Light Source. The results indicate
that as the nanoparticles oxidize, the radius of the crystalline core
decreases in size, which gives rise to a larger bandgap and consequently
to the observed blue-shift in the PL band. The correlation between the
PL, SXF, and NEXAFS results provides further support for the quantum
confinement mechanism as the origin of the visible PL in Si nanocrystals.
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