Binding Energy Of Hydrogenic Impurity Research Articles

Ground and two low-lying excited states binding energy in (Al,Ga)N/AlN double quantum wells: temperature and electric field effects

ABSTRACT In this study, using a numerical method within the effective mass approximation, we theoretically investigated the effects of temperature and electric field on the binding energy of an on-centre hydrogenic impurity in (Al,Ga)N/AlN double quantum wells. For rectangular, parabolic, and triangular finite potential confinements, the ground and the two lowest excited states binding energies are investigated. Regardless of the shape, our findings show that the size, temperature, and applied electric field induce huge impacts on the binding energy. It reveals that the binding energy (1) is higher in rectangular shape than for other forms, (2) is reduced as the temperature and/or electric field are increased, and (3) is less sensitive to temperature and applied electric field in rectangular confinement compared to other profiles. The results we obtained are very consistent with the literature findings.

Hydrostatic pressure, temperature, and electric field effects on the hydrogenic impurity binding energy in a multilayered spherical quantum dot

Hydrostatic pressure, temperature, and electric field effects on the hydrogenic impurity binding energy in a multilayered spherical quantum dot

Electronic properties and hydrogenic impurity binding energy of a new variant quantum dot

In this work, we have studied the electronic states with and without a donor impurity positioned on the first rectangular-shaped surface ( θ = 0°) of the new variant quantum dot (VQD) of azimuthal angle θ , radius R , and height H . The VQD takes several forms depending on the value of the geometric angle θ , which it passes from zero to the limit of 360° to reach the cylindrical form. Within the framework of the effective mass approximation and the limit of the infinite potential, we have obtained the eigenvalues from the Schrödinger equation by using the finite difference method (FDM). The binding energy is calculated after fixing the donor impurity at the center and the eccentric positions of the surface. Indeed, the binding energy takes the clear maximums when the impurity moves vertically and horizontally over the surface. It is very sensitive to each value of the geometric angle, the position of the impurity, the radius, and the height. We think that this new work may reveal important practical interests and provide another way to adjust electronic transitions in optoelectronic devices . • Electronic states and hydrogenic impurity binding energy of a new variant quantum dot is studied. • The effective mass approximation, the infinite potential and the finite difference method are adopted. • The binding energy is obtained after fixing the donor impurity at the center and the eccentric positions of the surface. • The energies depend to the geometric angle, the position of the impurity, the radius, and the height.

Binding energy and photoionization cross section of hydrogenic impurities in elliptic cylindrical core/shell quantum dots under a non-axial electric field

In this study, a donor impurity confined in an elliptic cylindrical core/shell quantum dot (ECCSQD) under a non-axial electric field is studied by using a variational and perturbation approach. We have investigated the binding energy and corresponding photoionization cross section (PCS) variation with the core and shell sizes, ellipticity constant, impurity position under the non-axial electric field. The results show that the binding energy with elliptic cylinder shape is lower than that with cylinder shape. The influence of electric field in different directions on the binding energy with different impurity positions is completely different. Even though for the on-center impurity, the influence is also very different due to the elliptic cylinder shape. The PCS for the incident radiation propagates perpendicular or parallel to the axis of the ECCSQD are both considered. The results show that the PCS in both causes completely depends on the direction of non-axial electric field and impurity position. In addition, the elliptic cylinder shape also has a significant influence on the peak intensity and position of PCS. • The elliptic cylindrical QD and non-axial electric field are both considered. • Binding energy with elliptic cylinder is lower than that with cylinder. • The PCS for perpendicular or parallel to the axis of the QD are both considered. • The PCS in both causes completely depends on the direction of electric field. • QD shape has a significant influence on the peak intensity and position of PCS.

Effect of electric field on photoionisation cross-section of impurity in multilayered quantum dot

The electron - impurity binding energy and photoionization cross-section of hydrogenic impurity are studied in spherical multilayered quantum dot AlxGa1-xAs/GaAs/AlyGa1-yAs driven by external electric field. The problem is solved in the framework of the effective mass approximation and rectangular potential profiles for wells and barriers, using the method of wave function expansion over a complete set of functions obtained as exact solutions of Schrodinger equation in nanostructure without impurity and electric field.

Impact of QW coupling on the binding energy in InGaN/GaN under the effects of the size, the impurity and the internal composition

In the present paper, the binding energy of hydrogenic shallow-donor impurity in simple and double coupled quantum wells based on unstrained wurtzite (In,Ga)N/GaN is investigated. Considering the effective-mass and dielectric mismatches between the well and its surrounding matrix, the numerical calculations are performed within the framework of the parabolic band and the single band effective-mass approximations under the finite potential barrier using finite element method (FEM). According to our results, it appears that the main effect of the wells coupling is to enhance the binding energy. It is also obtained that the binding energy is strongly sensitive to the internal and external parameters and can be adjusted by the quantum well/barrier width, the impurity position and the internal Indium composition. Our results are in good agreement with the finding especially for those obtained by the variational approach.

First-excited-state energy of hydrogenic impurity bound polaron in an anisotropic quantum dot in an electric field

The first-excited-state (ES) binding energy of hydrogenic impurity bound polaron in an anisotropic quantum dot (QD) is obtained by constructing a variational wavefunction under the action of a uniform external electric field. As for a comparison, the ground-state (GS) binding energy of the system is also included. We apply numerical calculations to KBr QD with stronger electron–phonon (E–P) interaction in which the new variational wavefunction is adopted. We analyzed specifically the effects of electric field and the effects of both the position of the impurity and confinement lengths in the xy-plane and the [Formula: see text] direction on the ground and the first-ES binding energies (BEs). The results show that the selected trial wavefunction in the ES is appropriate and effective for the current research system.

CdS/HgS Cylindrical Core/Shell: The simultaneous effect of the hydrostatic pressure and temperature on the diamagnetic susceptibility of hydrogenic donor impurity

One of the most important factors of controlling the properties of the above mentioned systems is hydrostatic pressure and temperature. The effect of the hydrostatic pressure and temperature on diamagnetic susceptibility and binding energy of a center hydrogenic donor impurity has been theoretically investigated in the framework of the effective mass approximation. We describe the quantum confinement by an infinite deep potential. The results for a cylindrical Inhomogeneous quantum dots made out of [CdS (Core) / HgS (Well) / CdS (Shell)] show that (i) when the hydrostatic pressure increase, the diamagnetic susceptibility decreases and the binding energy increases. (ii) The diamagnetic susceptibility increases with the temperature.

The External Electric and Magnetic Fields Effect on Binding Energy of Hydrogenic Donor Impurity in a InGaAsP/InP Core–Shell Quantum Dot

The External Electric and Magnetic Fields Effect on Binding Energy of Hydrogenic Donor Impurity in a InGaAsP/InP Core–Shell Quantum Dot

Pressure effect on the diamagnetic susceptibility of donor in HgS and GaAs cylindrical quantum dot

The binding energy and diamagnetic susceptibility of shallow hydrogenic impurity in cylindrical quantum dot is calculated using a variational approach within the effective mass approximation, as a function of dot size when the static pressure and the magnetic field are applied simultaneously. We describe the quantum confinement by an infinite deep potential; the numerical calculations are performed for HgS, which is a narrow gap, and GaAs, a large gap semiconductor. The results show that the diamagnetic susceptibility increases with the reduction in dot sizes and decreases when the hydrostatic pressure increases. We have shown that diamagnetic susceptibility strongly depends on size of the nanostructure and decreases with increasing size of the quantum dot and tends toward the limit of the bulk (−1, 1 a.u.) (increase in diamagnetic susceptibility in absolute value). We have found that the displacement of the impurity from the center of the quantum dot to the edge causes a decrease in the diamagnetic susceptibility. The absolute value of diamagnetic susceptibility of donors in GaAs is lower than in HgS.

The Binding Energy of Impurities in the Asymmetrical Semi-Exponential Quantum Wells

Within the framework of effective-mass and envelope wave function approach, using a variational method, we have investigated the binding energy of shallow-donor impurities in an asymmetrical semi-exponential quantum wells (ASEQW). The obtained numerical results show that the structure parameters (σ and, V0) lead to significant changes in the impurity binding energy. Furthermore, these results show that the hydrogenic donor impurity binding energy may be increased or decreased as a function of the impurity position in quantum well.

Role of a uniform magnetic field on the energy spectrum of a single donor in a core/shell spherical quantum dot

Using the variational approach within the framework of the effective-mass approximation (EMA), the binding energy of a centred hydrogenic donor impurity in a CdSe/ZnTe core/shell spherical quantum dot (CSSQD) in the presence of an external magnetic field was investigated. In this model, we have taken into account the effect of the radial dependence of the dielectric constant and of the electron effective mass. Our numerical results show a remarkable influence of the nanodot spatial parameters and of the external magnetic field strength on the shallow donor binding energy.

The impacts of electric and magnetic field on the binding energy of hydrogenic donor impurity in a InGaAsP/InP ring-shaped quantum well wire

The ground state binding energy of a hydrogenic donor impurity in a InGaAsP/InP ring-shaped quantum well wire is calculated via the plane wave basis method. It is shown that the donor binding energy is strongly dependent on the geometry, impurity position, axial electric field and transverse magnetic field. In particular, the impacts on the binding energy due to axial electric field and transverse magnetic field can mutually compensate.

Comparison of external electric and magnetic fields effect on binding energy of hydrogenic donor impurity in different shaped quantum wells

The effects of external electric and magnetic fields on the ground state binding energy of hydrogenic donor impurity are compared in square, V-shaped, and parabolic quantum wells. With the effective-mass envelope-function approximation theory, the ground state binding energies of hydrogenic donor impurity in InGaAsP/InP QWs are calculated through the plane wave basis method. The results indicate that as the quantum well width increases, the binding energy changes most fast in SQW. When the well width is fixed, the binding energy is the largest in VQW for the donor impurity located near the center of QWs. For the smaller and larger well width, the electric field effect on binding energy is the most significant in VQW and SQW, respectively. The magnetic field effect on binding energy is the most significant in VQW. The combined effects of electric and magnetic fields on the binding energy of hydrogenic donor impurity are qualitative consistent in different shaped QWs.

The Effect of Hermanson’s Spatial Dielectric Function on the Density of Impurity States in a Gallium Arsenide Quantum Dot of Rectangular Cross-Section

We have carried out a theoretical study of the effect of Hermanson’s spatial dielectric function on the density of impurity states (DOIS) for a shallow hydrogenic donor impurity located in the center of a Gallium Arsenide (GaAs) Quantum Well Dot (QWD) of rectangular cross-section. The density of impurity states (DOIS) of an unscreened (hydrogenic) donor impurity was calculated and compared with that of the screened (non-hydrogenic) donor impurity for the same system. Our calculations were carried out using a trial wave function within the effective mass approximation. Our calculations have been carried out with finite barriers. In this study, we first calculated the ground state binding energies of both hydrogenic and non-hydrogenic donor impurity for different dot sizes. The donor binding energies in the two regimes are then used to compute the DOIS. The results show that for both hydrogenic and non-hydrogenic donor impurities, the DOIS sharply rises to a peak, and then decreases almost exponentially with increase in binding energy. The results also show that the DOIS obtained for the non-hydrogenic donor impurities is markedly enhanced over that for purely hydrogenic donor impurities in which a dielectric constant is employed in the potential. In fact, the enhanced DOIS is observed throughout the range of values for binding energy considered. To a good extend there is good agreement between our results and those reported in the literature. It is therefore, important that the effect of the spatial dielectric function should be considered when designing optoelectronic devices.

Perturbation method for calculating impurity binding energy in an inhomogeneous cylindrical quantum dot with dielectric mismatch

In the present paper, we have studied the binding energy of the shallow donor hydrogenic impurity, which is confined in an inhomogeneous cylindrical quantum dot (CQD) of $$\hbox {GaAs-Al}_{x}\hbox {Ga}_{1-x}\hbox {As}$$ . Perturbation method is used to calculate the binding energy within the framework of effective mass approximation and taking into account the effect of dielectric mismatch between the dot and the barrier material. The ground-state binding energy of the donor is computed as a function of dot size for finite confinement. The result shows that the ground-state binding energy decreases with the increase in dot size. The result is compared with infinite dielectric mismatch as a limiting case. The binding energy of the hydrogenic impurity is maximum for an on-axis donor impurity.

The hydrostatic pressure and temperature effects on hydrogenic impurity binding energies in lattice matched InP/In0.53Ga0.47As/InP square quantum well

The on-center shallow-donor impurity binding energy in lattice matched InP/In0.53Ga0.47As square quantum well structure have been theoretically investigated using effective mass and variational techniques. The effects of hydrostatic pressure, temperature and well width has been calculated and the results are discussed.

Electric field effect on lowest excited-state binding energy of hydrogenic impurity in (In,Ga)N parabolic wire

Externally applied electric field and effective radius effects are investigated on the lowest excitedstate shallow-donor binding energy in (In,Ga)N-GaN parabolic wire within the framework of single band effective-mass approximation. The calculations are performed using the finite-difference method within the quasi-one-dimensional effective potential model. Our results reveal that: (i) the probability density is the largest on a circularity whose radius is the effective radius, (ii) the lowest excited-state binding energy is the largest for impurity located on this circularity while it starts to decrease when the impurity is away from the circularity and (iii) the binding energy is strongly-dependent on the complex interplay of spatial confinement, coulomb interaction and applied electric field.

The hydrostatic pressure and temperature effects on hydrogenic impurity binding energies in GaAs/InxGa1-xAs/GaAs square quantum well

We have calculated the ground state binding energy using variational methods and the effective mass approximation for the hydrogenic impurity in square quantum well structure made up of GaAs/InGaAs/GaAs epilayers under the action of hydrostatic pressure and temperature for different well widths and barrier heights. The effects of the variation of hydrostatic pressure and temperature can be summarized as follows; impurity binding energy is a negligibly decreasing function of temperature for fixed pressure and is an increasing function of pressure for fixed temperature.

The Binding Energy and Magnetic Susceptibility of an Off-Centre D0 Donor in the Presence of a Magnetic Field in a GaAs Quantum Dot with Gaussian Confinement: An Improved Treatment.

The binding energy and susceptibility of an off-centre neutral hydrogenic donor impurity (D0) trapped in a three-dimensional Gaussian quantum dot in the presence of an applied magnetic field are obtained by a variational method with an improved wave function. The results are obtained as a function of the quantum dot size, position of the impurity and the confinement strength.