BINDING ENERGY OF ACCEPTORS IN SEMIMAGNETIC QUANTUM DOTS

2006 ◽  
Vol 05 (01) ◽  
pp. 173-181 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Quantum Dots ◽  
Binding Energy ◽  
Bound States ◽  
Mean Field Theory ◽  
Mean Field ◽  
Binding Energies ◽  
Mass Approximation ◽  
Variational Calculations ◽  
Shallow Acceptors ◽  
Peak Value

The binding energies of shallow acceptors in Cd 1-x in Mn x in Te/ Cd 1-x out Mn x out Te quantum dots are calculated in the presence of external magnetic fields. Variational calculations are performed within effective mass approximation. The results show that the impurity binding energy (i) increases with the reduction in dot sizes, (ii) decreases with the magnetic field is increased for a given dot, and (iii) reaches a peak value as the dot radius decreases and then diminishes to a limiting value corresponding to the radius for which there are no bound states in the quantum dot. Spin polaronic shifts are estimated with the acceptor envelope function using a mean field theory. These results are compared with the existing literatures.

THE EFFECT OF POSITION DEPENDENT EFFECTIVE MASS OF HYDROGENIC IMPURITIES IN PARABOLIC GaAs/GaAlAs QUANTUM DOTS IN A STRONG MAGNETIC FIELD

2009 ◽  
Vol 23 (26) ◽  
pp. 5109-5118 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Binding Energy ◽  
Effective Mass ◽  
Bound States ◽  
Mass Approximation ◽  
Infinite Case ◽  
Dependent Mass ◽  
The Magnetic Field ◽  
Peak Value

The binding energy of shallow hydrogenic impurities in parabolic GaAs/GaAlAs quantum dots is calculated as a function of dot radius in the influence of magnetic field. The binding energy has been calculated following a variational procedure within the effective-mass approximation. Calculations are presented with constant effective-mass and position dependent effective masses. A finite confining potential well with depth is determined by the discontinuity of the band gap in the quantum dot and the cladding. The results show that the impurity binding energy (i) increases as the dot radius decreases for the infinite case, (ii) reaches a peak value around 1R* as the dot radius decreases and then diminishes to a limiting value corresponding to the radius for which there are no bound states in the well for the infinite case, and (iii) increases with the magnetic field. Also it is found that (i) the use of constant effective mass (0.067 m0) is justified for dot sizes ≥ a* where a* is the effective Bohr radius which is about 100 Å for GaAs , in the estimation of ionization energy and (ii) the binding energy shows complicated behavior when the position dependent mass is included for the dot size ≤ a*. These results are compared with the available existing literatures.

DONOR AND ACCEPTOR STATES IN GaAs-(Ga, Al)As QUANTUM DOTS: EFFECTS OF HYDROSTATIC PRESSURE AND AN INTENSE LASER

2010 ◽  
Vol 24 (29) ◽  
pp. 5761-5770 ◽  
Author(s):  
A. MIGUEZ ◽  
R. FRANCO ◽  
J. SILVA-VALENCIA
Keyword(s):  
Quantum Dots ◽  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Laser Field ◽  
Binding Energies ◽  
Field Amplitude ◽  
Pressure Effects ◽  
Intense Laser ◽  
Mass Approximation ◽  
Donor And Acceptor

We calculated the binding energies of shallow donors and acceptors in a spherical GaAs - Ga 1-x Al x As quantum dot under the combined effect of isotropic hydrostatic pressure and an intense laser. We used a variational approach within the effective mass approximation. The binding energy was computed as a function of hydrostatic pressure, dot sizes and laser field amplitude. The results showed that the impurity binding energy increases with pressure and decreases with the laser field amplitude when other parameters are fixed. We also found that the pressure effects are more dramatic for donor than acceptor impurities, especially for quantum dots with small radii.

EFFECT OF MAGNETIC FIELDS ON BINDING ENERGY OF IMPURITY STATES IN A SEMIMAGNETIC PARABOLIC QUANTUM DOT

2007 ◽  
Vol 21 (17) ◽  
pp. 3035-3044 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Magnetic Field ◽  
Binding Energy ◽  
Quantum Dot ◽  
Mean Field Theory ◽  
Mean Field ◽  
Realistic Model ◽  
Mass Approximation ◽  
Maximum Value ◽  
The Magnetic Field ◽  
Parabolic Quantum Dot

Using a variational approach, the binding energy of shallow hydrogenic impurities in a semimagnetic parabolic quantum dot is calculated within the effective mass approximation. The binding energy is computed for Cd 1-x in Mn x in Te / Cd 1-x out Mn x out Te structures as a function of the dot size in an external magnetic field. The results show that the impurity binding energy (i) increases with the reduction in dot sizes (ii) decreases when the magnetic field is increased for a given dot and (iii) increases to a maximum value at 100 Å and then decreases as the size of the dot increases beyond 100 Å for a realistic model. Spin polaronic shifts are estimated using a mean field theory. These results are compared with the existing literatures.

scholarly journals np-Pair Correlations in the Isovector Pairing Model

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1405
Author(s):  
Feng Pan ◽  
Yingwen He ◽  
Lianrong Dai ◽  
Chong Qi ◽  
Jerry P. Draayer
Keyword(s):  
Binding Energy ◽  
Occupation Number ◽  
Mean Field ◽  
Energy Difference ◽  
Binding Energies ◽  
Pair Correlations ◽  
Isospin Symmetry Breaking ◽  
Pairing Model ◽  
Proton Pairing ◽  
Spin Basis

A diagonalization scheme for the shell model mean-field plus isovector pairing Hamiltonian in the O(5) tensor product basis of the quasi-spin SUΛ(2) ⊗ SUI(2) chain is proposed. The advantage of the diagonalization scheme lies in the fact that not only can the isospin-conserved, charge-independent isovector pairing interaction be analyzed, but also the isospin symmetry breaking cases. More importantly, the number operator of the np-pairs can be realized in this neutron and proton quasi-spin basis, with which the np-pair occupation number and its fluctuation at the J = 0+ ground state of the model can be evaluated. As examples of the application, binding energies and low-lying J = 0+ excited states of the even–even and odd–odd N∼Z ds-shell nuclei are fit in the model with the charge-independent approximation, from which the neutron–proton pairing contribution to the binding energy in the ds-shell nuclei is estimated. It is observed that the decrease in the double binding-energy difference for the odd–odd nuclei is mainly due to the symmetry energy and Wigner energy contribution to the binding energy that alter the pairing staggering patten. The np-pair amplitudes in the np-pair stripping or picking-up process of these N = Z nuclei are also calculated.

RELATIVISTIC MEAN FIELD THEORETICAL FOUNDATION OF THE DROPLET MODEL FOR NUCLEI

2002 ◽  
Vol 11 (01) ◽  
pp. 55-65 ◽  
Author(s):  
CHUN-YUAN GAO ◽  
QI-REN ZHANG
Keyword(s):  
Mass Formula ◽  
Energy Surface ◽  
Theoretical Foundation ◽  
Mean Field Theory ◽  
Mean Field ◽  
Binding Energies ◽  
Droplet Model ◽  
Relativistic Mean Field ◽  
Theoretical Foundations ◽  
Type Mass

The binding energies per-nucleon for 1654 nuclei, whose mass numbers range from 16 to 263 and charge numbers range from 8 to 106, are calculated by the relativistic mean field theory, with finite nucleon size effect being taken into account. The calculated energy surface goes through the middle of experimental points, and the root mean square deviation for the binding energies per-nucleon is 0.08163 MeV. The numerical results may be well simulated by a droplet model type mass formula. The droplet model is therefore put on the relativistic mean field theoretical foundations.

scholarly journals Nonlinear Optical Rectification of Tuned Quantum Dots Under the Action of a Vertical Magnetic Field

2021 ◽  
Author(s):  
Zhuang Zhao
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Nonlinear Optical ◽  
Blue Shift ◽  
High Energy ◽  
Optical Rectification ◽  
Mass Approximation ◽  
Structure Plane ◽  
Nonlinear Optical Rectification ◽  
Peak Value

Abstract The effects of tuned quantum dots (QD) on the optical rectification (OR) coefficient under the action of the external magnetic field, hydrostatic pressure, temperature and quantum dot radius is theoretically studied in detail. The tuned quantum dots are subjected to a uniform magnetic field perpendicular to the structure plane. Within the framework of effective mass approximation and parabolic approximation, the energy level and wave function are derived, and the nonlinear optical rectification coefficients are calculated by the compact density matrix method and iterative method. Numerical results show that under different constraint parameters, the resonance peak of the OR coefficient moves in the direction of high energy or low energy, that is, red shift or blue shift. At the same time, the peak value of the OR coefficient will increase or decrease with the change of the parameters.

scholarly journals Positive and Negative Donor Impurity in an InAs/AlAs Quantum Wire

2010 ◽  
Vol 2 (3) ◽  
pp. 433
Author(s):  
N. Arunachalam ◽  
A. J. Peter
Keyword(s):  
Binding Energy ◽  
Quantum Wire ◽  
Optical Transition ◽  
Binding Energies ◽  
Impurity Level ◽  
Wire Radius ◽  
Emission Energy ◽  
Interband Optical Transition ◽  
Mass Approximation ◽  
Charged Donor

Binding energies of positive and negative charged donor impurities in an InAs/AlAs cylindrical quantum wire are investigated. Numerical calculations are performed using the variational procedure within the single band effective mass approximation. We assume that the impurity is located at the axis of the wire. The interband optical transition with and without the exciton is computed as a function of wire radius. The valence-band anisotropy is included in our theoretical model by using different hole masses in different spatial directions. Neutral shallow donors comprise a positively charged donor and a single bound electron. It is observed that (i) negative trions have a higher binding energy than positive trions, (ii) the binding energy of the heavy-hole exciton is much larger than that of the light-hole exciton due to different hole mass values (iii) the exciton binding energy and the interband emission energy are both increased when the radius of the cylindrical quantum wire is decreased and (iv) the effect of exciton influences the interband emission energy. Our results are in good agreement with the recent published results. Keywords: Quantum wire; Impurity level; Binding energy; Excitons. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i3.4715                 J. Sci. Res. 2 (3), 433-441 (2010)  

OPTICAL INTERSUBBAND TRANSITIONS AND BINDING ENERGIES OF DONOR IMPURITIES IN Ga1-xInxNyAs1-y/GaAs/Al0.3Ga0.7As QUANTUM WELL UNDER THE ELECTRIC FIELD

2012 ◽  
Vol 26 (06) ◽  
pp. 1250013 ◽  
Author(s):  
F. UNGAN ◽  
U. YESILGUL ◽  
E. KASAPOGLU ◽  
H. SARI ◽  
I. SOKMEN
Keyword(s):  
Binding Energy ◽  
Optical Absorption ◽  
Electric Field ◽  
Quantum Well ◽  
Applied Electric Field ◽  
Shallow Donor ◽  
Binding Energies ◽  
Intersubband Transitions ◽  
Mass Approximation ◽  
Intersubband Optical Absorption

The effects of nitrogen and indium mole concentration on the intersubband optical absorption for (1–2) transition and the binding energy of the shallow-donor impurities in a Ga 1-x In x N y As 1-y/ GaAs / Al 0.3 Ga 0.7 As quantum well under the electric field is theoretically calculated within the framework of the effective-mass approximation. Results are obtained for several concentrations of nitrogen and indium, and the applied electric field. The numerical results show that the intersubband transitions and the impurity binding energy strongly depend on the nitrogen and indium concentrations.

TEST OF NL-RA1 RELATIVISTIC EFFECTIVE INTERACTION FOR THE STRUCTURE OF DEFORMED AND SUPERHEAVY NUCLEI

2012 ◽  
Vol 21 (06) ◽  
pp. 1250055 ◽  
Author(s):  
M. RASHDAN
Keyword(s):  
Effective Interaction ◽  
Mean Field Theory ◽  
Mean Field ◽  
Superheavy Element ◽  
Decay Chain ◽  
Alpha Decay ◽  
Binding Energies ◽  
Superheavy Nuclei ◽  
Relativistic Mean Field ◽  
Relative Errors

The NL-RA1 effective interaction of the relativistic mean field theory is employed to study the structure of deformed and superheavy nuclei, using an axially deformed harmonic oscillator basis. It is found that a fair agreement with the experimental data is obtained for the binding energies (BE), deformation parameters and charge radii. Comparison with NL-Z2, NLSH and NL3 interactions show that NL-Z2 gives good binding but larger radii, while NL-SH gives good radii but larger binding. The NL-RA1 interaction is also tested for the new deformed superheavy element with Z≥98. Excellent agreement with the experimental binding is obtained, where the relative error in BEs of Cf, Fm, No, Rf, Sg and Ea (Z = 110) isotopes are found to be of the order ~0.1%. The NL3 predicted larger binding and larger relative errors ~0.2–0.5%. Furthermore, the experimental Q-values of the alpha-decay of the superheavy elements 270110, 288114 and 292116 are satisfactory reproduced by NL-RA1 interaction, where the agreement is much better than that predicted by the phenomenological mass FRDM model. Furthermore, the alpha-decay chain of element 294118 are also better reproduced by NL-RA1 interaction.

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