Browsing by Author "Duque, C. A."

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Citation - WoS: 13
Citation - Scopus: 16
Effects of Surface Curvature and Electric Field on Electronic and Optical Properties of an Off-Center Hydrogenic Donor Impurity in 2D Nanostructures
(Springer Heidelberg, 2024) Chouef, S.; Mommadi, O.; Boussetta, R.; Hbibi, M.; El Moussaouy, A.; Sahin, M.; Duque, C. A.
In this study, we have explored how the curvature of a surface affects the electronic and optical properties of hydrogenic donor impurity within both flat and curved two-dimensional nanostructure, subject to an external electric field. In order to ascertain the energy states and their associated wave functions, we have numerically solved the Schrodinger equation using the effective mass approximation and finite difference method. Utilizing the resulting energy values and wave functions, we have computed binding energy, transition energy, curvature effect, optical absorption coefficient, and oscillator strength of an off-center hydrogenic impurity in a 2D quantum dot nanostructure. Furthermore, we have conducted a thorough analysis of how an electric field and geometrical confinement influence the spectrum of a confined electron-impurity. Our findings reveal that variations in radius and angle of curvature, applied electric field, and impurity position exert profound impacts on the electronic and optical properties of 2D-nanostructures.
Citation - WoS: 40
Citation - Scopus: 44
Optical Properties in a ZnS/CdS Core/Shell Spherical Quantum Dot: Electric and Magnetic Field and Donor Impurity Effects
(MDPI, 2023) Toscano-Negrette, Rafael G.; Leon-Gonzalez, Jose C.; Vinasco, Juan A.; Morales, A. L.; Koc, Fatih; Kavruk, Ahmet Emre; Duque, C. A.
A theoretical analysis of optical properties in a ZnS/CdS/ZnS core/shell/shell spherical quantum dot was carried out within the effective mass approximation. The corresponding Schrodinger equation was solved using the finite element method via the 2D axis-symmetric module of COMSOL-Multiphysics software. Calculations included variations of internal dot radius, the application of electric and magnetic fields (both oriented along z-direction), as well as the presence of on-center donor impurity. Reported optical properties are the absorption and relative refractive index change coefficients. These quantities are related to transitions between the ground and first excited states, with linearly polarized incident radiation along the z-axis. It is found that transition energy decreases with the growth of internal radius, thus causing the red-shift of resonant peaks. The same happens when the external magnetic field increases. When the strength of applied electric field is increased, the opposite effect is observed, since there is a blue-shift of resonances. However, dipole matrix moments decrease drastically with the increase of the electric field, leading to a reduction in amplitude of optical responses. At the moment impurity effects are activated, a decrease in the value of the energies is noted, significantly affecting the ground state, which is more evident for small internal radius. This is reflected in an increase in transition energies.