The Dependence of Confinement Energy on the Size of Quantum Dots

H. I. Ikeri¹ , A. I. Onyia² , ³ , O. J. Vwavware⁴

Section:Research Paper, Product Type: Isroset-Journal
Vol.7 , Issue.2 , pp.27-30, Apr-2019

CrossRef-DOI:   https://doi.org/10.26438/ijsrpas/v7i2.2730

Online published on Apr 30, 2019

Copyright © H. I. Ikeri, A. I. Onyia, , O. J. Vwavware . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
 

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Abstract :
Theoretical study of the dependence of confinement energy on the size of Quantum dots (QDs) using quantum mechanical approach is presented. A simple model obtained for confinement energy is generally found to be in good agreement with the predicted inverse quadratic dependence on the dot size. Thus optical and electronic behavior of QDs can be engineered during manufacturing to meet specific applications. It is found that energy levels of the charge carriers within QDs are increased yielding to discrete energy states for electrons and holes. Therefore, QDs can emit and absorb light at specific wavelengths which are related to QD size. The plots for ground state confinement energy as a function of dots radius for CdSe, GaAs and ZnS QDs show monotonous decay curves. Thus as the dot radius increases, the ground state confinement energy decreases exponentially but never reaches zero. Thus, charge carriers in quantum dots possess non-zero minimum energy state in consistence with the infinite potential well. It can be observed that making the dot size large enough the effect of size on confinement energy is very small for different QDs. This is because as QDs grow larger their energy levels move closer and form a near continuum. In addition, among the QDs considered the degree of confinement on the CdSe and GaAs QDs strongly indicates that their optical wavelength can be extended to match the solar spectrum for multi-junction solar cells applications. This improves the solar to electricity conversion efficiency by harvesting multiple portions of solar spectrum.

Key-Words / Index Term :
Nanotechnology, Quantum Dot, Confinement, Confinement Energy, Potential well, Solar cell, and Quantum Mechanics

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