Binding Energy Of Donor Impurity Research Articles

Effect of interdiffusion on impurity states in quantum dots of spherical symmetry

The effect of interdiffusion of Al and Ga atoms on the binding energy of the hydrogen-like shallow donor impurity in spherically symmetric GaAs/Ga 1− x Al x As quantum dot is investigated. The dependence of the binding energy on the diffusion length, as well as on dot radius and impurity position are obtained. It is shown that the dependence of the binding energy on the diffusion length has non-monotonic behavior in both the cases of on- and off-center impurity and can be significantly different for varied values of the dot radius and the distance of impurity from the dot center.

Shallow Donor Impurity Binding Energy in a V-Shaped Quantum Well Under Intense Laser Field

Shallow Donor Impurity Binding Energy in a V-Shaped Quantum Well Under Intense Laser Field

Photoionization cross-section and binding energy of donor impurities in GaAs, Ge and Si quantum wires with infinite barriers

Within the effective-mass approximation, we have investigated the binding energies of donor impurities as a function of the wire dimensions and the photoionization cross-section for a hydrogenic donor impurity placed on the center of the quantum well-wire as a function of the normalized photon energy in the GaAs, Ge and Si quantum wires with infinite barriers. The calculations are performed by the variational method based on a two-parametric trial wave function. The results show that the impurity binding energy and the photoionization cross-section depend strongly on both wire dimensions and material parameters.

Bound polaron in a wurtzite nitride semiconductor ellipsoidal quantum dot

The binding energy of a hydrogenic donor impurity in weakly oblate ellipsoidal quantum dot is investigated with a variational method by taking the electron couples with both branches of the mixing properties of the LO and TO polarizations (LO-like and TO-like phonons) due to the anisotropic effect into account. The interaction between impurity and phonons has also been considered to obtain the binding energy of bound polaron. The numerical computation has been performed for wurtzite nitride semiconductor GaN. The results show that the binding energy of bound polaron is reduced by the phonons effect on the impurity states. It indicates that the contribution of LO-like phonon to the binding energy is dominant, and the anisotropic angle and ellipticity influence on the binding energy are small.

HYDROGENIC IMPURITY IN A QUANTUM WIRE: EFFECT OF DIFFERENT MASSES OF WIRE AND BARRIER

A variational calculation is given within the effective mass approximation of the binding energy of a hydrogenic donor impurity located on the axis of an infinitely long circular quantum well wire. A uniform magnetic field is applied along the axis of the wire. The different effective masses of the wire and the barrier are taken into consideration. This has not been done hitherto in the presence of the magnetic field. New analytical expressions for the electron energy levels and the binding energies of the hydrogenic impurity in the ground and the first four excited states have been derived. Moreover, the form of the binding energy reported in earlier works in the special case of zero magnetic field has been amended. A new form of the trial wavefunction has also been introduced. It has the advantage of satisfying the required boundary conditions in the case of different masses of the wire and barrier, and thus it resembles the exact solution in this respect. The new form of the trial wavefunction has been applied to the case of the ground state. It has improved the results of binding energy considerably as they tend to approach the exact solution from below.

Binding energies of donor impurities in modulation-doped [formula omitted] double quantum wells under an electric field

In this study, we have investigated theoretically the binding energies of shallow donor impurities in modulation-doped GaAs/Al 0.33Ga 0.67As double quantum wells (DQWs) under an electric field which is applied along the growth direction for different doping concentrations as a function of the impurity position. The electronic structure of modulation-doped DQWs under an electric field has been investigated by using a self-consistent calculation in the effective-mass approximation. The results obtained show that the carrier density and the depth of the quantum wells in semiconductors may be tuned by changing the doping concentration, the electric field and the structure parameters such as the well and barrier widths. This tunability gives a possibility of use in many electronic and optical devices.

Influence of strain on hydrogenic impurity states in a GaN/Al x Ga1−x N quantum dot

Within the effective-mass approximation, we calculated the influence of strain on the binding energy of a hydrogenic donor impurity by a variational approach in a cylindrical wurtzite GaN/AlxGa1−xN strained quantum dot, including the strong builtin electric field effect due to the spontaneous and piezoelectric polarization. The results show that the binding energy of impurity decreases when the strain is considered. Then the built-in electric field becomes bigger with the Al content increasing and the binding energy of hydrogenic donor impurity decreases when the Al content is increasing. For dot height L < 2 nm, the change of the binding energy is very small with the Al content variety.

External electric field effect on the hydrogenic donor impurity in zinc-blende GaN/AlGaN cylindrical quantum dot

The binding energy of a hydrogenic donor impurity in a zinc-blende GaN/AlGaN cylindrical quantum dot (QD) is calculated in the framework of effective-mass envelope-function theory using the plane wave basis. It is shown that the donor binding energy is highly dependent on the impurity position and QD size. The external electric field induces an asymmetrical distribution of the donor binding energy with respect to the center of the QD. The maximum of the donor binding energy is shifted from the center of the QD. The degenerating energy levels for symmetrical positions with respect to the center of QD are also split. The splitting increases with the increase in QD height while the splitting increases up to a maximum and then decreases with the increase in QD radius. In the presence of the external electric field, the donor binding energy is insensitive to dot height when the impurity is located at the left side of the QD with large dot height. In addition, Stark shift dependence on hydrogenic impurity position is calculated.

Binding energy of donor impurities in double inverse parabolic quantum well under electric field

In this study, effects of the electric field applied along the growth direction on the binding energy of donor impurities in double inverse parabolic quantum well (DIPQW) with different well and barrier widths, as well as different Al concentrations in the center of the wells have been investigated. The Al concentration at the barriers was always x max=0.3. The calculations were performed within the effective mass approximation, using a variational method.

The hydrostatic pressure and temperature effects on donor impurities in GaAs/Ga 1 − xAl xAs double quantum well under the external fields

The combined effects of hydrostatic pressure and temperature on donor impurity binding energy in GaAs/Ga 0.7Al 0.3As double quantum well in the presence of the electric and magnetic fields which are applied along the growth direction have been studied by using a variational technique within the effective-mass approximation. The results show that an increment in temperature results in a decrement in donor impurity binding energy while an increment in the pressure for the same temperature enhances the binding energy and the pressure effects on donor binding energy are lower than those due to the magnetic field.

Effect of temperature on the binding energy of excited states in a ridge quantum wire

In this paper, we study the influence of temperature on the binding energy of a hydrogenic donor impurity in a ridge quantum wire using a variational procedure within the effective mass approximation. We calculate the binding energy of the donor impurity in its ground state and first few excited states in a V-groove GaAs / Ga 1 - x Al x As quantum wire for various impurity positions and different temperatures. We find that the temperature and impurity locations can have important effect in the binding energy of the donor impurity.

The electric field effect on binding energy of hydrogenic impurity in zinc-blende GaN/AlxGa1−xN spherical quantum dot

Within the framework of effective mass approximation, the binding energy of a hydrogenic donor impurity in zinc-blende GaN/AlxGa1−xN spherical quantum dot (QD) is investigated using the plane wave basis. The results show that the binding energy is highly dependent on impurity position, QD size, Al content and external field. The binding energy is largest when the donor impurity is located at the centre of the QD and the binding energy of impurity is degenerate for symmetrical positions with respect to the centre of QD without the external electric field. The maximum of the donor binding energy is shifted from the centre of QD and the degenerating energy levels for symmetrical positions with respect to the centre of QD are split in the presence of the external electric field. The binding energy is more sensitive to the external electric field for the larger QD and lower Al content. In addition, the Stark shift of the binding energy is also calculated.

Electric field effect in a GaAs/AlAs spherical quantum dot

Using a variational procedure within the effective-mass approximation we calculate the binding and normalized binding energy (NE bF) of a shallow donor impurity in a GaAs/AlAs spherical quantum dot, under the action of constant uniform electric field applied in the z-direction. A proper choice of the dot radius and electric field can largely change NE bF of a centre shallow impurity in the spherical quantum dot, which may be used to feel the small change in the dot radius.

External Electric Field Effect on Hydrogenic Donor Impurity in Zinc-Blende InGaN Quantum Dot

The binding energy of a hydrogenic donor impurity in zinc-blende (ZB) InGaN quantum dot (QD) is calculated in the framework of effective-mass envelope-function theory using the plane wave basis. It is shown that the donor binding energy is highly dependent on the impurity position, QD size and the external electric field. The symmetry of the electron probability distribution is broken and the maximum of the donor binding energy is shifted from the centre of QD in the presence of the external electric field. The degenerating energy levels for symmetrical positions with respect to the centre of QD are split. The splitting increases with the increase of QD height while the splitting increases up to a maximum value and then decreases with the increase of QD radius.

EFFECTS OF MAGNETIC AND ELECTRIC FIELDS ON THE HYDROGENIC IMPURITY IN AN ELLIPSOIDAL PARABOLIC QUANTUM DOT

The binding energy of a hydrogen-like impurity in an ellipsoidal parabolic quantum dot under the magnetic and electric fields have been discussed by using the effective mass approximation and the variational method. We have calculated the effects of the magnetic and electric fields on the binding energy of donor impurities in the quantum dots with different confinement potentials. We conclude that the structural confinement is very effective, and especially in the weak confinement potential case the magnetic field dependence of the donor binding energy is more pronounced.

Hydrogenic impurity states in wurtzite GaN/AlGaN coupled quantum dots

The ground-state binding energy of a hydrogenic donor impurity in wurtzite (WZ) GaN/AlGaN coupled quantum dots (QDs) is calculated by means of a variational method, considering the strong built-in electric fields caused by the piezoelectricity and spontaneous polarizations. The strong built-in electric fields induce an asymmetrical distribution of the ground-state binding energy with respect to the center of the coupled QDs. If the impurity is located at the low dot, the ground-state binding energy is insensitive to the interdot barrier width of WZ GaN/AlGaN coupled QDs.

Binding energy and photoionization cross section of hydrogen-like donor impurity in quantum well-wire in electric and magnetic fields

The effect of uniform electric and magnetic fields on binding energy and photoionization cross-section of an off-axis hydrogen-like donor impurity in a QWW, approximated by a cylindrical well of finite depth, is investigated within the framework of variational approach. The dependencies of the binding energy and photoionization cross-section on electric field strength, magnetic field induction, wire radius and impurity position are obtained. The cases when the polarization vector of incident radiation is parallel and perpendicular to the wire axis are both discussed.

Binding energy of a hydrogen-like donor impurity in a quantum well-wire in magnetic and electric fields

The effect of a longitudinal magnetic and a transverse electric fields on the binding energy of a hydrogen-like donor impurity is studied for a semiconductor quantum well-wire approximated by a cylindrical well of finite depth. It is shown that the magnetic and electric fields as well as the impurity distance from the wire axis are the effective tools for the influence on the binding energy.

Phonons effects on the binding energy of a hydrogenic impurity in a superlattice GaAs-Ga1-xAlxAs

The Electron-Longitudinal Optical (LO) Phonon effects on the binding energy of shallow donor impurity in a superlattice GaAs-Ga1-xAlxAs are investigated. The calculations are made using the effective mass approximation within the variational approach for a superlattice potential described by the Kroning-Penney model. Our results are obtained as a function of parameters which characterize the superlattice and the position of the impurity center. The present results could be useful in understanding the spatial distribution of the donor center in the superlattice.

Binding energy and photoionization cross-section of a hydrogen-like donor impurity in a quantum well-wire in a magnetic field

The effect of a uniform longitudinal magnetic field on the binding energy and photoionization cross-section of a hydrogen-like donor impurity is studied for a semiconductor quantum well-wire approximated by a cylindrical well of finite depth. The selection rules and analytical expressions for the photoionization cross-section are obtained depending on the magnetic field induction, impurity position, and light wave polarization.