Nms Sermathai Vasan College For Women

Madurai, India

Nms Sermathai Vasan College For Women

Madurai, India
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Christina Lily Jasmine P.,Nms Sermathai Vasan College For Women | John Peter A.,P.A. College | Lee C.W.,Kyung Hee University
Chemical Physics | Year: 2015

Electronic and optical properties of a hydrogenic donor impurity in a CdTe/Zn0.2Cd0.8Te/ZnTe core/shell/shell quantum dot are discussed taking into consideration of geometrical confinement effect. The confining potentials on both the sides of the barrier are different and a two parametrical potential of Smorodinsky-Winternitz is considered in this problem. The dielectric mismatch is included in the Hamiltonian. The position dependent effective mass is applied. The electronic properties are studied using variational method and the optical properties are investigated using the density matrix approach. The intersubband optical absorption, the oscillator strength and the radiative life time between ground and the excited states are studied based on the wave functions and the confined energies with and without the impurity with various dot radii. The results show that the absorption wavelength in type-II core and shell semiconducting nanomaterials can be tuned over a wider range of wavelengths by altering their size and the composition. © 2015 Elsevier B.V. All rights reserved.


Minimala N.S.,Nms Sermathai Vasan College For Women
Journal of Nano- and Electronic Physics | Year: 2012

Heavy hole exciton binding energies as functions of dot radius and the Mg alloy content in a ZnO/MgxZn1-xO quantum dot are investigated. The effects of strain, including the hydrostatic and the biaxial strain, and the internal electric field, due to spontaneous and piezoelectric polarization are taken into account. Numerical calculations are performed using variational procedure within the single band effective mass approximation. The nonlinear optical rectification is investigated for different dot radius and the values of Mg alloy content in a ZnO/MgxZn1-xO quantum dot taking into account the strain-induced piezoelectric effects. The results show that the resonant peak of the nonlinear optical rectification is blue shifted with the confinement effect and the Mg alloy content. © 2012 Sumy State University.


Minimala N.S.,Nms Sermathai Vasan College For Women | Lee C.W.,Kyung Hee University
Phase Transitions | Year: 2013

The effects of hydrostatic pressure on the exciton ground-state binding energy and the interband emission energy in a GaN/Alx Ga1- xN quantum dot are investigated. The effects of strain and the internal field due to spontaneous and piezo-electric polarizations are included in the Hamiltonian. Numerical calculations are performed using variational procedure within the framework of single-band effective-mass approximation. The dependence of non-linear optical processes on the dot sizes is brought out in the influence of pressure. Pressure-induced optical properties are obtained using the compact density matrix approach. The effects of hydrostatic pressure on the linear, third-order non-linear optical absorption coefficients and the refractive index changes of the exciton as a function of photon energy are calculated. Our results show that the effects of pressure and the geometrical confinement have great influence on the optical properties of GaN/Alx Ga1- xN dot. © 2013 Taylor and Francis Group, LLC.


Minimala N.S.,Nms Sermathai Vasan College For Women | Yoo C.K.,Kyung Hee University
Superlattices and Microstructures | Year: 2013

Effect of magnetic field on exciton binding energy is investigated in a strained wurtzite GaN/Al0.2Ga0.8N quantum dot in which the strong built-in electric field due to the spontaneous and piezoelectric polarizations is included. Numerical calculations are performed using variational procedure within the single band effective mass approximation by the magnetic field strength. The magnetic field induced interband emission energy of a strained GaN/AlGaN quantum dot is investigated with and without the effect of internal field. The exciton oscillator strength and the exciton lifetime for radiative recombination as a function of dot radius with the effect of magnetic field strength are computed. The total optical absorption coefficients and the changes of refractive index as a function of normalized photon energy in the presence of built-in internal field are analyzed in the presence of magnetic field. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and the magnetic field. The occurred blue shift of the resonant peak due to the magnetic field will give the information about the variation of two energy levels in the quantum dot. The optical absorption coefficients and the refractive index changes are strongly dependent on the incident optical intensity, the internal field and the magnetic field. © 2013 Elsevier Ltd. All rights reserved.


Minimala N.S.,Nms Sermathai Vasan College For Women | Lee C.W.,Kyung Hee University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2013

Electric field induced exciton binding energy as a function of dot radius in a ZnO/Zn1-xMgxO quantum dot is investigated. The interband emission as a function of dot radius is obtained in the presence of electric field strength. The Stark effect on the exciton as a function of the dot radius is discussed. The effects of strain, including the hydrostatic and the biaxial strain and the internal electric field, induced by spontaneous and piezoelectric polarization are taken into consideration in all the calculations. Numerical calculations are performed using variational procedure within the single band effective mass approximation. Some nonlinear optical properties are investigated for various electric field strengths in a ZnO/Zn 1-xMgxO quantum dot taking into account the strain-induced piezoelectric effects. Our results show that the nonlinear optical properties strongly depend on the effects of electric field strength and the geometrical confinement. © 2012 Elsevier B.V.

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