The defect corrections to the polarization and dielectric functions of conduction electrons in a quantum well are first calculated. Following this, we derive the first two moment equations from the semi-classical Boltzmann transport theory and apply them to explore defect effects on magneto-transport of electrons. In addition, we obtain analytically momentum-relaxation time and mobility tensor of electrons by using the defect-corrected polarization function. Based on quantum-statistical theory, we further investigate the defect capture and charging dynamics by employing a hydrogen-like quantum-mechanics model for point defects and going beyond a short-range δ-function for their probability functions. Finally, both the capture and relaxation rates, as well as the density for captured electrons, are studied as functions of temperature, subband-electron density and different types of defects, which can be utilized for quantifying burst noise in transistors and blinking noise in photo-detectors.
The valley-dependent skew scattering of conduction electrons by impurities in two-dimensional α-T3 materials is studied. The interplay of Lorentz and Berry forces, which act on mobile electrons in position and momentum spaces respectively, is quantified. Interactions of electrons with ionized impurities at two valleys are observed in different scattering directions. Both the zeroand first-order Boltzmann moment equations are used for calculating scattering-angle distributions of resulting skew currents, which are significantly enhanced by introducing microscopic inverse energy- and momentum-relaxation times to two moment equations.
The effects of lattice point defects on the absorption of incident photons in a single-quantum-well
system are investigated by using a quantum-statistical theory. Our self-consistent theoretical
model includes the defect-induced vertex correction to an unscreened dynamical polarization
function of doped electrons under the ladder approximation. Meanwhile, the intralayer dynamical
screening to the Coulomb interaction between charged point defects and conduction
electrons are also taken into account within the random-phase approximation. The numerical
results for nonlinear variations in absorption spectra by defects are demonstrated and analyzed
for various defect densities. The combination of the current theory with a space-weather forecast
model will enable novel designs of satellite onboard electronic and optoelectronic devices with
radiation-hardening protection and extended lifetimes. More specifically, this theory facilitates
a better characterization of photodetectors not only for high quantum efficiency and low dark
current density but also for radiation tolerance or mitigation of radiation damage.
We have formulated a theory for investigating the conditions which are required to achieve entangled states
of electrons on graphene and three-dimensional (3D) topological insulators (TIs). We consider the quantum
entanglement of spins by calculating the exchange energy. A gap is opened up at the Fermi level between the
valence and conduction bands in the absence of doping when graphene as well as 3D TIs are irradiated with
circularly-polarized light. This energy band gap is dependent on the intensity and frequency of the applied
electromagnetic field. The electron-photon coupling also gives rise to a unique energy dispersion of the dressed
states which is different from either graphene or the conventional two-dimensional electron gas (2DEG). In our
calculations, we obtained the dynamical polarization function for imaginary frequencies which is then employed to
determine the exchange energy. The polarization function is obtained with the use of both the energy eigenstates
and the overlap of pseudo-spin wave functions. We have concluded that while doping has a significant influence
on the exchange energy and consequently on the entanglement, the gap of the energy dispersions affects the
exchange slightly, which could be used as a good technique to tune and control entanglement for quantum
information purposes.
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