Electronic band structure of GaAs/AlxGa1−xAs superlattice in an intense laser field

ABSTRACT: We perform theoretical calculations for the band structure of semiconductor superlattice under intense high-frequency laser field. In the frame of the non-perturbative approach, the laser effects are included via laser-dressed potential. Results reveal that an intense laser field creates an additional geometric confinement on the electronic states. Numerical results show that when tuning the strength of the laser field significant changes come in the electronic energy levels and density of states

The effect of magnetic field on the impurity binding energy of shallow donor impurities in a Ga1−xInxNyAs1−y/GaAs quantum well

ABSTRACT: Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga1−xInxNyAs1−y/GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations

Linear and nonlinear optical absorption coefficients and refractive index changes in Morse quantum wells under electric field

In this paper, we investigate theoretically the effects of electric field on the linear and nonlinear optical properties of Morse quantum wells considering a two-level system. The effective mass approximation and the envelope function approach are used to calculate the energy levels and wave functions. The analytical expressions of the optical properties are obtained by using the compact density-matrix approach. The linear and third-order nonlinear optical absorption coefficients and the refractive index changes are investigated as a function of the incident photon energy for several configurations of the structural parameter and the applied electric field. Numerical results, presented for a typical GaAs/AlGaAs quantum well, reveal that the electric field has a significant effect on the optical characteristics of these structures and intersubband transitions can be modified by tuning the structural range parameter of the potential

Electric-field-induced Nonlinear Optical Rectification, Second- and Third-harmonic Generation in Asymmetrical Quantum Well

The effects of a static electric field on the nonlinear optical rectification, second- and third-harmonic generation in a quantum well described by Morse potential are theoretically investigated. Analytical expressions for the optical coefficients due to intersubband optical transitions with an applied electric field are extracted from the compact-density matrix approach and iterative scheme. Numerical results presented for a typical GaAs quantum well reveal the feasibility of control of optical transitions between the size-quantized subbands. In addition, we have to emphasize the fact that the optical response of the system is remarkably sensitive to the electric field and structural range parameter

Colle-Salvetti-type local density functional for the exchange-correlation energy in two dimensions

We derive an approximate local density functional for the exchange-correlation energy to be used in density-functional calculations of two-dimensional systems. In the derivation we employ the Colle-Salvetti wave function within the scheme of Salvetti and Montagnani [Phys. Rev. A 63, 052109 (2001)] to satisfy the sum rule for the exchange-correlation hole. We apply the functional to the two-dimensional homogeneous electron gas as well as to a set of quantum dots and find a very good agreement with exact reference data

Laser-induced nonlinear optical rectification in a two-dimensional quantum pseudodot system

In this work, the effects of intense laser field on the nonlinear optical rectification in a two-dimensional quantum pseudodot system subjected to an uniform external magnetic field have been investigated theoretically. The non-resonant monochromatic intense laser field with circular polarization has been taken into account within the framework of high-frequency Floquet theory. Analytical expression for the coefficient of nonlinear optical rectification is deduced by using the compact-density matrix approach and iterative method. Numerical results show that the nonlinear optical rectification coefficient depends strongly on the magnitude of magnetic field, the chemical potential and zero point of the pseudoharmonic potential. Moreover, we have demonstrated that the strength of intense laser field alters the structure of confinement potential and affects remarkably the nonlinear optical rectification coefficients

Shape effects on the ground-state energy of a three-electron quantum dot

In this work we will theoretically study the ground-state electronic structure of three-electron polygonal quantum dots by means of the configuration interaction method. Transition from a weakly correlated regime to a strongly correlated regime is investigated for quantum dots with hexagonal, square, and triangular geometries. Our numerical results reveal that the ground-state spin and the charge density distribution of the system are sensitive to the shape of the quantum dot

Electron transport in electrically biased inverse parabolic double-barrier structure

A theoretical study of resonant tunneling is carried out for an inverse parabolic double-barrier structure subjected to an external electric field. Tunneling transmission coefficient and density of states are analyzed by using the non-equilibrium Green's function approach based on the finite difference method. It is found that the resonant peak of the transmission coefficient, being unity for a symmetrical case, reduces under the applied electric field and depends strongly on the variation of the structure parameters

Effects of a scattering center on the ground-state energy of quantum-dot lithium

In this paper, the effects of a repulsive scattering center on the ground-state energy and spin properties of a three-electron parabolic quantum dot are investigated theoretically by means of configuration interaction method. Phase transition from a weakly correlated regime to a strongly correlated regime is examined from several strengths and positions of Gaussian impurity. Numerical results reveal that the transition from spin-1/2 to spin-3/2 state depends strongly on the location of the impurity which accordingly states the controllability of the spin polarization. Moreover, broken circular symmetry results in more pronounced electronic charge localization

Spin texturing in quantum wires with Rashba and Dresselhaus spin-orbit interactions and in-plane magnetic field

In this work, we investigate the effects of interplay of spin-orbit interaction and in-plane magnetic fields on the electronic structure and spin texturing of parabolically confined quantum wire. Numerical results reveal that the competing effects between Rashba and Dresselhaus spin-orbit interactions and the external magnetic field lead to a complicated energy spectrum. We find that the spin texturing owing to the coupling between subbands can be modified by the strength of spin-orbit couplings as well as the magnitude and the orientation angle of the external magnetic field