International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Special Issue: 09 | Sep -2017
p-ISSN: 2395-0072
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One Day International Seminar on Materials Science & Technology (ISMST 2017) 4th August 2017 Organized by
Department of Physics, Mother Teresa Women’s University, Kodaikanal, Tamilnadu, India
Photo-ionization Cross-Section and Binding Energy of Exciton in a Parabolic Quantum Well P. Ravikashree1, A. Anitha2, M. Arulmozhi3 1,3Department
of Physics, Jayaraj Annapackiam College for Women (Autonomous) Periyakulam 625601, Theni District, Tamilnadu, India. 2Mother Teresa Women's University, Kodaikanal, Tamil Nadu, India. ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Parabolic quantum well has attracted
Meshad et al [2] have showed the binding energy of a neutral donor in GaAs-Alx Ga1-xAs parabolic quantum well is determined variationally, the changes in the binding energy of donors are calculated, for different well sizes and depths. Wang et al [3] have calculated the ground and first excitedstate binding energies of a hydrogenic donor in a rectangular quantum dot (RQD) in the presence of electric field. M. Arulmozhi [4] have calculated donor binding energies in nano-quantum wells with parabolic confinement and the result shows that binding energy of donor increases when the external pressure increases and the binding energy decreases when the temperature increases.
considerable attention of the researchers because of its applications such as speed circuits, optical devices etc. Binding energies of ground and excited states of heavy hole exciton and light hole exciton in a parabolic quantum well composed of GaAs/Ga1-xAlxAs with potential profile proportional to have been calculated as a function of wellwidth (L) and Al concentration (x). The photo-ionization cross-section of exciton has been calculated as the function of photon energy and wellwidth (L) by variational method. The results show that the binding energy decreases with increased wellwidth of the quantum well but increases with Al concentration. The photo-ionization cross-section decreases with increased photon energy but increases as wellwidth increases. The photo-ionization cross section is a useful tool to detect positions of charge carriers inside the quantum structures.
E.C.Niculescu [5] have calculated the effective mass approximation for the states of single and double donors in a finite parabolic quantum well is presented. The validity of the infinite-parabolic-well approximation is also discussed. Alvarado-Reyes et al [6] have investigated the binding energy of impurity as a function of the impurity position and wellwidth within the effective mass approximation using a variational approach. The results show that an inverse parabolic quantum well turns into a parabolic quantum well with the effect of the magnetic field. El-Meshand et al [7] have calculated the binding energy of an exciton bound to the quantum well structure is then determined using a standard variational technique. Arulmozhi et al [8] have calculated the binding energy of near triangular quantum well (NTQW) in magnetic field and also calculated the binding energy of exciton in ZnSe/Zn1-xMgxSe quantum well with Poschl-teller Potential [9].
Key Words: Exciton, Binding energy, Photo-ionization crosssection, Parabolic quantum well
1. INTRODUCTION There has been tremendous interest in the study of structural, electronic and optical properties of low dimensional structures during past few years due to its potential applications in opto-electronic device fabrication. It is possible to fabricate the nanostructures such as quantum wells, quantum wires and quantum dots with various potential profiles like Rectangular, Triangular, Near Triangular and surface using the advanced epitaxial growth techniques such as molecular beam epitaxy (MBE) and metal organic chemical vapour deposition (MOCVD).
El-Meshad et.al [10] have solved variationally the binding energy of a neutral donor in GaAsAl x/Ga1-xAs parabolic quantum well, the changes in the binding energy of donors are calculated for different well sizes and depths. El-said et.al [11] have calculated the photo-ionization cross-section on photon energy for shallow donors in a finite barrier GaAs/Ga1-xAsAlx quantum wells as the binding energy as a function of well width. One of important approximations have been made in this work is to take the second subband states as the final state in the photo-ionization process, because the photo-ionization cross-section approximations
The Quantum wells with parabolic profile (Parabolic quantum well - PQW) have been studied by several researchers. Yuan Lihua et al have studied the binding energies of the ground state and excited state of a hydrogenic donor in the ZnO parabolic quantum well [1].
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