Effect of deuterium substitution for hydrogen in surface functionalisation of hydrophilic nanosilicon particles on their spectral and dynamic propertiesстатья
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Дата последнего поиска статьи во внешних источниках: 5 декабря 2014 г.
Аннотация:Broadband femtosecond spectroscopy has been used to
study two types of hydrophilic silicon nanoparticles: (1) photoluminescent,
passivated with deuterium and oxidised in fully deuterated
dimethyl sulphoxide, and (2) nonluminescent (control samples having
a similar crystalline core), passivated with hydrogen and oxidised
in dimethyl sulphoxide. We have found significant differences
in ultrafast spectral – temporal induced absorption dynamics
between the two types of nanoparticles in the energy range corresponding
to their calculated band gap. The observed distinction is
due to the considerably higher oxidation rate of silicon on the surface
of the deuterated samples in comparison with the undeuterated
ones and with the associated increase in the number of photoluminescence
centres on the surface of the nanoparticles. In the samples
containing self-trapped exciton (STE) energy states responsible for
the photoluminescence in the red spectral region, carrier capture at
these levels and carrier relaxation to the ground state have characteristic
times in the femtosecond range. In the samples free of STE
states, excited carriers relax to the conduction band bottom in a
characteristic time of several picoseconds.