Donor impurity related optical and electronic properties of cylindrical GaAs-AlxGa1−x As quantum dots under tilted electric and magnetic fields

Abstract

this article makes a theoretical study of the optical and electronic properties in cylindrical GaAs-Al x Ga 1−x As quantum dots in the presence of an arbitrarily located donor impurity and considering the simultaneous effects of tilted electric and magnetic fields. The studies are developed in the effective mass and parabolic band approximations. the solution of the Schrödinger equation is done through the finite element method considering tetrahedral meshes that can be adapted to regions where there are abrupt variations of the materials that make up the structure. Among the many results, reported for the first time in this article, we can mention: (i) the electronic spectrum, without and with shallow donor impurity, considering separate and combined effects of tilted electric and magnetic fields, (ii) the ground state binding energy as a function of the external electric and magnetic fields, their orientations concerning the axial axis of the quantum dot, and the impurity position, (iii) the squared reduced dipole matrix elements for impurity related inter-level optical transitions as a function of the tilted electric and magnetic fields and impurity position, and (iv) the optical absorption coefficient between the ground state and at least the first fifteen lowest excited states under tilted electric and magnetic fields and considering several impurity positions. From this study it can be concluded that the presence of tilted electric and magnetic fields and on-center or off-center shallow donor impurities, ostensibly enrich the optical and electronic properties of the system. It is observed that due to the rupture of the azimuthal symmetry of the cylindrical quantum dot, important modifications of the selection rules for inter-level transitions between states appear.

Binding Energy And Absorption of Donor Impurity In Spherical GaAs/AlxGa1-x As Quantum Dots With Konwent Potential

“…In the calculation of the Ω-and Γ-functions, according to Eqs. ( 14) and (15), it is evident that these are dominated by the behavior of the dipole matrix elements. Then, Fig.…”

“…For this reason, QDs are very important topics for researchers both theoretically and experimentally. As well as the geometric form and size of the confinement potential of QDs [4][5][6][7][8][9], the externally applied electric, magnetic and intense laser fields [10][11][12][13][14][15][16][17][18][19] affect the electronic properties, which influences the optical properties of QD. In devices based on QDs, the effects caused by impurities are also quite important and thus there are a lot of researches involving impurity-related studies with a special focus on QDs [20][21][22][23][24][25].…”

Shallow Donor Impurity States with Excitonic Contribution in GaAs/AlGaAs and CdTe/CdSe Truncated Conical Quantum Dots under Applied Magnetic Field

“…174 eV, and ε = 13 [46,57]. In this subsection, the impurity and static magnetic field effects on GaAs-Al 0.3 Ga 0.7 As truncated conical QD are explored.…”

First Study on the Electronic and Donor Atom Properties of the Ultra-Thin Nanoflakes Quantum Dots

“…In the past thirty years, scientists have paid considerable attention to the shape of the nanostructures, which is one of the most important factors to study the different properties of QD. In-depth researchers have been interested in spherical, cylindrical, and core/shell QD under external perturbation such as hydrostatic pressure, temperature, and electric and magnetic field [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. It is important to note that the optical properties associated with off-center hydrogenic impurity states confined in cylindrical QD with various electric and magnetic fields directions have been reported by Heyn and Duque [ 30 ].…”

“…In-depth researchers have been interested in spherical, cylindrical, and core/shell QD under external perturbation such as hydrostatic pressure, temperature, and electric and magnetic field [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. It is important to note that the optical properties associated with off-center hydrogenic impurity states confined in cylindrical QD with various electric and magnetic fields directions have been reported by Heyn and Duque [ 30 ]. In this report, the authors show that the contribution of an off-donor impurity leads to extremely complex energy spectra, reduced squared dipole matrix elements, and optical absorption coefficients.…”