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Revathi M.,Yadava College Govindarajan Campus | Yoo C.,Kyung Hee University | John Peter A.,Government Arts and Science College
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2010

Magneto-exciton bound donor is investigated theoretically in a GaN/Ga 1-xAlxN quantum dot within the framework of single band effective mass approximation and compared with the experimental results. Binding energies on excitons bound hydrogenic donors and the diamagnetic susceptibility are obtained as a function of dot radius and magnetic field. The valence-band anisotropy is included in our theoretical model using different hole masses in different spatial directions. Zeeman effect is calculated through the energy dependent effective mass. The dependence of donor bound exciton diamagnetic shift is found. The interband optical transition of GaN/Ga1-xAl xN dot is computed with various structural parameters in the influence of magnetic field. Our results show that (i) quantum size, the magnetic field and the interband optical transitions have a considerable influence on neutral donor exciton states, (ii) the diamagnetic susceptibility increases with the magnetic field and is not pronounced for smaller dot radii and (iii) the found diamagnetic shift is agreed with the other experimental investigator [Yoichi Yamada et al., 2000 [26]]. © 2010 Elsevier B.V. Source


Narayanan M.,Yadava College Govindarajan Campus | Peter A.J.,Government Arts and Science College
Journal of Computational and Theoretical Nanoscience | Year: 2013

Magnetic field induced binding energy, interband emission energy and the non-linear optical properties of exciton as functions of dot radius and magnetic field strength in an InSb/InGaxSb1-x quantum dot are investigated. Numerical calculations are carried out using single band effective mass approximation variationally to compute the exciton binding energy and optical properties are obtained using the compact density matrix approach. The dependence of the nonlinear optical processes on the dot sizes is investigated for various magnetic field strength. The linear, third order non-linear optical absorption coefficients, susceptibility values and the refractive index changes of magneto-exciton as a function of photon energy are obtained. It is found that magnetic field strength and the geometrical confinement have great influence on the optical properties of dots. Copyright © 2013 American Scientific Publishers. Source


Nalini P.,Yadava College Govindarajan Campus | Peter A.J.,Government Arts and Science College
Chinese Physics Letters | Year: 2011

Positively charged donor exciton binding energy is computed as a function of quantum-dot size within the single band effective mass approximation for different Mn contents in Cd 1-xin Mn xin Te/Cd 1-xout Mn xout Te. The exciton bound polaron is computed for 0 ≤ x ≤ 0.08, on the Mn mole fraction. We determine the energy gap using the mean field approximation and incorporate the exchange interaction between the carrier and the magnetic impurity. The interband emission energy is studied with the height and radius of the cylindrical quantum dot. Valence-band anisotropy is included in our theoretical model using different hole masses in different spatial directions. Spin polaronic shifts as functions of quantum-dot radius and Mn concentration are estimated using the mean field theory. It is found that (i) the energy gap depends on the Mn mole fraction, (ii) it increases linearly with an increase in Mn content, and (iii) the effect is more pronounced for a narrow dot, showing the quantum size effects. Our results are in good agreement with other recently published reports. © 2011 Chinese Physical Society and IOP Publishing Ltd. Source


Narayanan M.,Yadava College Govindarajan Campus | John Peter A.,Government Arts and Science College
Superlattices and Microstructures | Year: 2012

The effect of electric field on the binding energy, interband emission energy and the non-linear optical properties of exciton as a function of dot radius in an InSb/InGa xSb 1-x quantum dot are investigated. Numerical calculations are carried out using single band effective mass approximation variationally to compute the exciton binding energy and optical properties are obtained using the compact density matrix approach. The dependence of the nonlinear optical processes on the dot sizes is investigated for various electric field strength. The linear, third order non-linear optical absorption coefficients, susceptibility values and the refractive index changes of electric field induced exciton as a function of photon energy are obtained. It is found that electric field and the geometrical confinement have great influence on the optical properties of dots. © 2012 Elsevier Ltd. All rights reserved. Source


Narayanan M.,Yadava College Govindarajan Campus | John Peter A.,Kyung Hee University | Yoo C.K.,Kyung Hee University
Physica B: Condensed Matter | Year: 2012

Binding energy, interband emission energy and the non-linear optical properties of exciton in an InSb/InGa xSb 1-x quantum dot are computed as functions of dot radius and the Ga content. Optical properties are obtained using the compact density matrix approach. The dependence of non-linear optical processes on the dot sizes is investigated for different Ga concentrations. The linear, third order non-linear optical absorption coefficients, susceptibility values and the refractive index changes of the exciton are calculated for different concentrations of gallium content. It is found that gallium concentration has great influence on the optical properties of InSb/InGa xSb 1-x dots. © 2011 Elsevier B.V. All rights reserved. Source

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