11 research outputs found
Analysis of the carrier transport in molecularly doped polymers using the multiple trapping model with the Gaussian trap distribution
AbstractWe have performed the comprehensive analysis of the time of flight curves using the multiple trapping model with the Gaussian trap distribution. Our analysis shows that flat plateaus on the computed curves are rare events. We have shown numerically that plateau formation for the non-equilibrium transport may be due to the presence of a thin defective (depletion) layer on the sample surface (two-layer model of a polymer film). Also, to describe the Poole–Frenkel effect, we have explicitly introduced an analogous field dependence for the frequency factor
Transition absorption as a mechanism of surface photoelectron emission from metals
Transition absorption of electromagnetic field energy by an electron passing
through a boundary between two media with different dielectric permittivities
is considered both classically and quantum mechanically. It is shown that
transition absorption can make a substantial contribution to the process of
electron photoemission from metals due to the surface photoelectric effect.Comment: 4 pages, 3 figure
Internal photoemission from plasmonic nanoparticles: comparison between surface and volume photoelectric effects
We study emission of photoelectrons from plasmonic nanoparticles into
surrounding matrix. We consider two mechanisms of the photoelectric effect from
nanoparticles - surface and volume ones, and use models of these two effects
which allow us to obtain analytical results for the photoelectron emission
rates from nanoparticle. Calculations have been done for the step potential at
surface of spherical nanoparticle, and the simple model for the hot electron
cooling have been used. We highlight the effect of the discontinuity of the
dielectric permittivity at the nanoparticle boundary in the surface mechanism,
which leads to substantial (by 5 times) increase of photoelectron emission rate
from nanoparticle compared to the case when such discontinuity is absent. For
plasmonic nanoparticle, a comparison of two mechanisms of the photoeffect was
done for the first time and showed that surface photoeffect, at least, does not
concede the volume one, which agrees with results for the flat metal surface
first formulated by Tamm and Schubin in their pioneering development of
quantum-mechanical theory of photoeffect in 1931. In accordance with our
calculations, this predominance of the surface effect is a result of effective
cooling of hot carriers, during their propagation from volume of the
nanoparticle to its surface in the scenario of the volume mechanism. Taking
into account both mechanisms is essential in development of devices based on
the photoelectric effect and in usage of hot electrons from plasmonic
nanoantenna.Comment: 13 pages, 10 figures, 61 reference
Bulk Photoemission from Plasmonic Nanoantennas of Different Shapes
We elaborate a semi-analytical model for calculation of the bulk internal emission of photoelectrons from metal nanoparticles into a semiconductor matrix. We introduce important effects in the model as the jump of the effective electron mass at the metal−semiconductor interface and cooling of the hot electrons because of electron−electron and electron−nanoparticle surface collisions in the metal. We study the interplay between the plasmonic electric dipole and quadrupole resonances and reveal the optimum parameters for different geometrical shapes of nanoparticles with respect to the photoemission cross section. We find that the absorption cross section well-predicts the optimum size of the dipolar nanoparticle. This opens the possibility for the fast optimization and design of the photoelectric devices