scholarly journals Investigation of Light Absorption in a ZnS Quantum Dot

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Hojjatollah K. Salehani ◽  
Maedeh Zakeri
Keyword(s):  
Magnetic Field ◽  
Optical Absorption ◽  
Quantum Dot ◽  
Excited States ◽  
Light Absorption ◽  
Blue Shift ◽  
Optical Absorption Coefficient ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
The Magnetic Field

The light absorption of a ZnS quantum dot with a parabolic confinement potential is studied in this paper in the presence of magnetic field perpendicular to dot plane. The Schrodinger equation of a single electron is solved numerically, and energy spectra and wave functions are obtained. Then, the optical absorption coefficients in transition from ground state to different excited states are calculated. The effects the magnetic field and quantum dot width on the optical absorption are investigated. It is found that the optical absorption coefficient has a blue shift by increasing of magnetic field or confinement strength of quantum dot.

IMPURITY LEVELS IN A PARABOLIC QUANTUM DOT UNDER ACTION OF A STRONG MAGNETIC FIELD

2001 ◽  
Vol 15 (31) ◽  
pp. 4103-4110 ◽  
Author(s):  
E. M. KAZARYAN ◽  
L. S. PETROSYAN ◽  
H. A. SARKISYAN
Keyword(s):  
Magnetic Field ◽  
Energy Level ◽  
Quantum Dot ◽  
Excited States ◽  
Adiabatic Approximation ◽  
Impurity States ◽  
Parabolic Confinement ◽  
Analytical Expressions ◽  
Ground Energy ◽  
Parabolic Quantum Dot

The impurity states in quantum dot with parabolic confinement were studied in adiabatic approximation. The analytical expressions for the energy of ground and excited states were obtained. It was shown, that the influence of walls results in raising the ground energy level.

ABSORPTION OF A HYDROGENIC DONOR QUANTUM DOT WITH MAGNETIC FIELD

2010 ◽  
Vol 24 (07) ◽  
pp. 657-663 ◽  
Author(s):  
JINSHENG HUANG ◽  
JIANHUI YUAN
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Quantum Dot ◽  
Optical Absorption Coefficient ◽  
Hydrogenic Donor ◽  
The Matrix ◽  
Diagonalization Method ◽  
Linear Optical Properties ◽  
Matrix Diagonalization ◽  
The Magnetic Field

An investigation of the optical properties of a hydrogenic donor in a disc-like parabolic quantum dot with magnetic field has been performed by using the matrix diagonalization method. The optical absorption coefficient between the ground (L = 0) and the first excited state (L = -1) have been examined based on the computed energies and wavefunctions. We found that the linear optical properties of the hydrogenic donor in QDs are strongly affected by the confinement strength and the magnetic field strength.

scholarly journals Magnetocaloric Effect in Non-Interactive Electrons Systems: ``The Landau Problem'' and Its Extension to Quantum Dot

2018 ◽  
Author(s):  
Oscar A. Negrete ◽  
Francisco J. Peña ◽  
Juan M. Florez ◽  
Patricio Vargas
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Magnetocaloric Effect ◽  
Cyclotron Frequency ◽  
The Other ◽  
Optimal Region ◽  
Potential Trap ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
Strong Degeneration

In this work, we report the magnetocaloric effect (MCE) in two systems of non-interactive particles, the first corresponds to the Landau problem case and the second, the case of an electron in a quantum dot subjected to a parabolic confinement potential. In the first scenario, we realize that the effect is totally different from what happens when the degeneration of a single electron confined in a magnetic field is not taken into account. In particular, when the degeneracy of the system is negligible, the magnetocaloric effect cools the system, while in the other case, when the degeneracy is strong, the system heats up. For the second case, we study the competition between the characteristic frequency of the potential trap and the cyclotron frequency to find the optimal region that maximizes the ΔT of the magnetocaloric effect, and due to the strong degeneration of this problem, the results are in coherence with those obtained for the Landau problem. Finally, we consider the case of a transition from a normal MCE to an inverse one and back to normal as a function of temperature. This is due to the competition between the diamagnetic and paramagnetic response when the electron spin in the formulation is included.

Effect of the charges of impurity on the absorption of quantum dot with magnetic field

2018 ◽  
Vol 32 (16) ◽  
pp. 1850202
Author(s):  
Jinsheng Huang ◽  
Gengxin Chen
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
State Energy ◽  
Optical Absorption Coefficient ◽  
Hydrogenic Impurity ◽  
The Matrix ◽  
Diagonalization Method ◽  
Matrix Diagonalization ◽  
The Magnetic Field ◽  
Parabolic Quantum Dot

An investigation of the effect of charges of impurity on the optical properties of a hydrogenic impurity in a disk parabolic quantum dot under magnetic field has been performed by using the matrix diagonalization method. The ground state energy level becomes lower as the charges of impurity increase. The optical absorption coefficient strongly reduces with increasing charges of impurity and is strongly affected by the confinement strength, the magnetic field strength, and density of electron.

scholarly journals Effect of confinement potential shape on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot at finite temperature

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
K. Luhluh Jahan ◽  
Bahadir Boyacioglu ◽  
Ashok Chatterjee
Keyword(s):  
Magnetic Field ◽  
Heat Capacity ◽  
Quantum Dot ◽  
Transport Properties ◽  
Average Energy ◽  
Persistent Current ◽  
Confinement Potential ◽  
Potential Shape ◽  
Gaas Quantum Dot ◽  
The Magnetic Field

Abstract The effect of the shape of the confinement potential on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot is studied using the power-exponential potential model with steepness parameter p. The average energy, heat capacity, magnetic susceptibility and persistent current are calculated using the canonical ensemble approach at low temperature. It is shown that for soft confinement, the average energy depends strongly on p while it is almost independent of p for hard confinement. The heat capacity is found to be independent of the shape and depth of the confinement potential at low temperatures and for the magnetic field considered. It is shown that the system undergoes a paramagnetic-diamagnetic transition at a critical value of the magnetic field. It is furthermore shown that for low values of the potential depth, the system is always diamagnetic irrespective of the shape of the potential if the magnetic field exceeds a certain value. For a range of the magnetic field, there exists a window of p values in which a re-entrant behavior into the diamagnetic phase can occur. Finally, it is shown that the persistent current in the present quantum dot is diamagnetic in nature and its magnitude increases with the depth of the dot potential but is independent of p for the parameters considered.

Effect of temperature on magnetic susceptibility and thermodynamic properties of an asymmetric quantum dot in tilted magnetic field

2015 ◽  
Vol 29 (23) ◽  
pp. 1550127 ◽  
Author(s):  
R. Khordad
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Quantum Dot ◽  
Specific Heat ◽  
Energy Levels ◽  
Effect Of Temperature ◽  
Magnetic Field Direction ◽  
Asymmetric Quantum ◽  
Gaas Quantum Dot ◽  
The Magnetic Field

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.

INTERSUBBAND OPTICAL ABSORPTION COEFFICIENTS AND REFRACTIVE INDEX CHANGES OF AN ELLIPSOIDAL FINITE POTENTIAL QUANTUM DOT

2010 ◽  
Vol 19 (01) ◽  
pp. 131-143 ◽  
Author(s):  
G. REZAEI ◽  
M. R. K. VAHDANI ◽  
M. BARATI
Keyword(s):  
Refractive Index ◽  
Light Intensity ◽  
Optical Absorption ◽  
Quantum Dot ◽  
Absorption Coefficient ◽  
Optical Absorption Coefficient ◽  
Matrix Formalism ◽  
Ellipsoidal Quantum Dot ◽  
Index Changes ◽  
Intersubband Optical Absorption

Intersubband optical absorption coefficient and refractive index changes of a weakly prolate ellipsoidal quantum dot, using the compact-density matrix formalism and iterative method, are investigated. In this regard, the linear and nonlinear intersubband optical absorption coefficient and refractive index changes of a GaAs / Al x Ga 1-x As ellipsoidal quantum dot, as functions of the dot radius, ellipticity constant, stoichiometric ratio and incident light intensity are calculated. The results indicate that absorption coefficient and refractive index changes strongly depend on the light intensity, size and geometry of the dot and structure parameters such as aluminium concentration in GaAs / Al x Ga 1-x As structures.

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