scholarly journals Shallow Donor Impurity States with Excitonic Contribution in GaAs/AlGaAs and CdTe/CdSe Truncated Conical Quantum Dots under Applied Magnetic Field

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2832
Author(s):  
Lorenz Pulgar-Velásquez ◽  
José Sierra-Ortega ◽  
Juan A. Vinasco ◽  
David Laroze ◽  
Adrian Radu ◽  
...  

Using the effective mass approximation in a parabolic two-band model, we studied the effects of the geometrical parameters, on the electron and hole states, in two truncated conical quantum dots: (i) GaAs-(Ga,Al)As in the presence of a shallow donor impurity and under an applied magnetic field and (ii) CdSe–CdTe core–shell type-II quantum dot. For the first system, the impurity position and the applied magnetic field direction were chosen to preserve the system’s azimuthal symmetry. The finite element method obtains the solution of the Schrödinger equations for electron or hole with or without impurity with an adaptive discretization of a triangular mesh. The interaction of the electron and hole states is calculated in a first-order perturbative approximation. This study shows that the magnetic field and donor impurities are relevant factors in the optoelectronic properties of conical quantum dots. Additionally, for the CdSe–CdTe quantum dot, where, again, the axial symmetry is preserved, a switch between direct and indirect exciton is possible to be controlled through geometry.

2013 ◽  
Vol 483 ◽  
pp. 170-173
Author(s):  
An Mei Wang

A method is proposed to exactly diagonalize the Hamiltonian of a N-layer quantum dot containing a single electron in each dot in arbitrary magnetic fields. the energy spectra of the dot are calculated as a function of the applied magnetic field. We find disco-ntinuous ground-state energy transitions induced by an external magnetic field in the case of strong coupling. However, in the case of weak coupling, such a transition does not occur and the angular momentum remains zero.


2019 ◽  
Vol 33 (34) ◽  
pp. 1950422 ◽  
Author(s):  
Mohammad Elsaid ◽  
Mohamoud Ali ◽  
Ayham Shaer

We present a theoretical study to investigate the effect of donor impurity on the magnetization (M) and the magnetic susceptibility [Formula: see text] of single electron quantum dot (QD) with Gaussian confinement in the presence of a magnetic field. We solve the Hamiltonian of this system, including the spin, by using the exact diagonalization method. The ground state binding energy (BE) of an electron has been shown as a function of QD radius and confinement potential depth. The behaviors of the magnetization and the magnetic susceptibility of a QD have been studied as a function of temperature, confinement potential depth, quantum radius and magnetic field. We have shown the effect of donor impurity on the magnetization and magnetic susceptibility curves of Gaussian quantum dot (GQD).


2015 ◽  
Vol 29 (23) ◽  
pp. 1550127 ◽  
Author(s):  
R. Khordad

In this paper, the specific heat, entropy and magnetic susceptibility of an asymmetric GaAs quantum dot (QD) are studied under the influence of temperature and a tilted external magnetic field. We first calculate the analytical wave functions and energy levels using a transformation to simplify the Hamiltonian of the system. Then, we obtain the analytical expressions for specific heat, entropy and magnetic susceptibility as the function of temperature, magnetic field and its direction for various anisotropy of the system. According to the results obtained from the present work, we find that (i) the specific heat and entropy are decreased when the magnetic field increases. (ii) When anisotropy is increased, the specific heat and entropy decrease. (iii) At large magnetic fields, the anisotropy has not important effect on specific heat and entropy. In briefly, the magnetic field, magnetic field direction and anisotropy play important roles in the specific heat, entropy and magnetic susceptibility of an asymmetric QD.


1991 ◽  
Vol 58 (24) ◽  
pp. 2833-2835 ◽  
Author(s):  
H. Teshima ◽  
A. Oishi ◽  
H. Izumi ◽  
K. Ohata ◽  
T. Morishita ◽  
...  

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