Hydrogenic Impurity in Ridge Quantum Wire

The binding energies as well as wave functions of hydrogenic impurities located in V-groove GaAs/Al x Ga 1−x As quantum wires are calculated for different positions of the impurity inside the wires. The variational method is used and the carrier ground states are analytically calculated by an effective potential scheme together with a suitable coordinate transformation that allows the decoupling of the two-dimensional Schrodinger equation. The results are in good agreement with experimental points and other previous investigations

Hydrogenic donor impurity in a cubic quantum dot: effect of position-dependent effective mass

In this paper, we intend to study the effect of variable mass on the binding energy. In this regard, we apply an analytic expression for position-dependent effective mass in a cubic quantum dot. Then, we obtain the binding energies of a shallow donor in the quantum dot of GaAs/AlxGa1−xAs using a variational procedure within the effective mass approximation. Calculations are presented with a constant effective mass and position-dependent effective mass. It is found that (i) the binding energy decreases as the dot length increases in both the cases of constant and variable masses, (ii) an increase of binding energy is observed when the spatially varying mass is included, and (v) the binding energy shows complicated behavior when the position-dependent mass is included for the small dot size L ≤ 130 Å

Diamagnetic susceptibility of hydrogenic donor impurity in a V-groove GaAs/Ga

In this work, the diamagnetic susceptibility and the binding energy of a hydrogenic donor impurity both in the parabolic and non-parabolic conduction band models have been calculated within the effective mass approximation for a V-groove GaAs/Ga1-xAlxAs quantum wire. According to the results obtained from the present work reveals that (i) the value of diamagnetic susceptibility due to the non-parabolicity effect is higher than that of parabolicity effect; (ii) the values of diamagnetic susceptibility and binding energy due to the non-parabolicity effect is not appreciable at low Al mole fractions; (iii) the diamagnetic susceptibility approaches to the bulk value both in L $\rightarrow$ 0 or L $\rightarrow$ ∞; (iv) the effect of non-parabolocity is not appreciable in the binding energy and energy dependent effective mass, for energies lower than 50 MeV

Simultaneous effects of pressure, temperature, and external magnetic field on absorption threshold frequency of tuned quantum dot/ring systems:an analytical study

In the present study, a tuned quantum dot/ring system under the simultaneous effects of temperature, pressure, and an external magnetic field is investigated. The energy eigenvalues and wave functions are analytically derived using the Laplace transform. Then, an analytical expression for the interband light absorption coefficient is derived. Also, we obtain an analytical expression for the absorption threshold frequency (ATF) of the system. It is observed that (i) the ATF decreases when the pressure rises; (ii) the ATF increases with an increase in the magnetic field and with increasing temperature; and (iii) we can optimize the ATF by varying the pressure, temperature, and magnetic field

Simultaneous effects of pressure, temperature, and external magnetic field on absorption threshold frequency of tuned quantum dot/ring systems:an analytical study

In the present study, a tuned quantum dot/ring system under the simultaneous effects of temperature, pressure, and an external magnetic field is investigated. The energy eigenvalues and wave functions are analytically derived using the Laplace transform. Then, an analytical expression for the interband light absorption coefficient is derived. Also, we obtain an analytical expression for the absorption threshold frequency (ATF) of the system. It is observed that (i) the ATF decreases when the pressure rises; (ii) the ATF increases with an increase in the magnetic field and with increasing temperature; and (iii) we can optimize the ATF by varying the pressure, temperature, and magnetic field

Analytical study of absorption threshold frequency of tuned quantum dot/ring system

In the present work, a tuned quantum dot/ring system under an external magnetic field is studied. Analytical methods are used to derive the wave functions and energy eigenvalues. The interband light absorption coefficient is then calculated analytically. Additionally, an analytical relationship is derived for the absorption threshold frequency (ATF) of the system. It is observed using those analytical formulas that: i) The ATF behaves differently for large and small magnetic fields. ii) The ATF increases as the magnetic field is increased and decreases as system size is increased. iii) The ATF can be increased by enhancing the repulsive potential of the system. Our results show that the model can be transformed into either a 2D quantum disk or ring, offering the possibility of using our findings about the absorption coefficient and ATF in photodetectors based on 2D quantum dots

The structural and thermodynamical properties of binary ellipsoidal fluid mixture Gay-Berne interaction

In this paper, a uniform classical fluid mixture comprising ellipsoidal molecules is studied. This mixture is composed of two types of ellipsoidal molecules interacting through the Gay-Berne potential with different sizes at temperature T. For this system, the Ornstein-Zernike equation using the Percus-Yevick closure relation is solved. Then the direct correlation function, pair correlation function and the pressure of the fluid at temperature T are calculated. The obtained results are in agreement with the previous theories and the results of molecular dynamic computer simulation

Pure iron nanoparticles prepared by electric arc discharge method in ethylene glycol

Pure iron nanoparticles (NPs) are fabricated using a simple and low-cost electric arc-discharge method in ethylene glycol (EG). The effect of different arc discharge currents (10, 20 and 30 A) on the size and optical absorption of the NPs is studied. Dynamic light scattering (DLS) and UV-visible spectroscopy data indicate that at the arc current of 10 A, the size of the particles is about 103 nm, and it can raise the arc current leading to larger NPs. UV-visible spectroscopy data show that the solvent gets more and more transparent with time, an effect which, sonication, proves that is related to agglomeration of the NPs. The evidence of pure Fe NPs is investigated by means of X-ray diffraction (XRD) measurement the average size of which is about 14 nm using Scherrer’s relation. Magnetization measurements of the samples are carried out by alternating gradient force magnetometer (AGFM). These results have shown that the arc discharge method is an effective method for preparing magnetic fluids in one step and EG is the effective medium for caring Fe NPs against oxidation. Therefore, the method can pave the way for the synthesis of other NPs such as Fe, Fe-Co, Fe-Pt and iron oxide