74 research outputs found
Electron surface scattering kernel for a plasma facing a semiconductor
Employing the invariant embedding principle for the electron backscattering
function, we present a strategy for constructing an electron surface scattering
kernel to be used in the boundary condition for the electron Boltzmann equation
of a plasma facing a semiconducting solid. It takes the microphysics
responsible for electron emission and backscattering from the interface into
account. To illustrate the approach, we consider silicon and germanium,
describing the interface potential by an image-step and impact ionization
across the energy gap as well as scattering on phonons and ion cores by a
randium-jellium model. The emission yields deduced from the kernel agree
sufficiently well with measured data, despite the simplicity of the model, to
support its use in the boundary condition of the plasma's electron Boltzmann
equation.Comment: 14 pages, 10 figure
About the quantum-kinetic derivation of boundary conditions for quasiparticle Boltzmann equations at interfaces
Quite a many electron transport problems in condensed matter physics are
analyzed with a quasiparticle Boltzmann equation. For sufficiently slowly
varying weak external potentials it can be derived from the basic equations of
quantum kinetics, provided quasiparticles can be defined and lead to a pole in
the quantum-mechanical propagators. The derivation breaks down, however, in the
vicinity of an interface which constitutes an abrupt strong perturbation of the
system. In this contribution we discuss in a tutorial manner a particular
technique to systematically derive, for a planar, nonideal interface, matching
conditions for the quasi-particle Boltzmann equation. The technique is based on
pseudizing the transport problem by two auxiliary interface-free systems and
matching Green functions at the interface. Provided quasiparticles exist in the
auxiliary systems, the framework can be put onto the semiclassical level and
the desired boundary conditions result. For ideal interfaces, the conditions
can be guessed from flux conservation, but for complex interfaces this is no
longer the case. The technique presented in this work is geared towards such
interfaces.Comment: accepted version with corrected typos in Eqs. (6), (30), (32), and
(40); 13 pages, 3 figure
Exciton formation in strongly correlated electron-hole systems near the semimetal-semiconductor transition
The region surrounding the excitonic insulator phase is a three-component
plasma composed of electrons, holes, and excitons. Due to the extended nature
of the excitons, their presence influences the surrounding electrons and holes.
We analyze this correlation. To this end, we calculate the density of bound
electrons, the density of electrons in the correlated state, the
momentum-resolved exciton density, and the momentum-resolved density of
electron-hole pairs that are correlated but unbound. We find qualitative
differences in the electron-hole correlations between the weak-coupling and the
strong-coupling regime.Comment: 10 pages, 5 figure
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