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 Schrödinger 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.

Within the framework of effective mass theory, we investigate the effects of spin–orbit interaction (SOI) and Zeeman splitting on the electronic properties of an electron confined in GaAs single quantum rings. Energies and envelope wavefunctions in the system are determined by solving the Schrödinger equation via the finite element method. First, we consider an inversely quadratic model potential to describe electron confining profiles in a single quantum ring. The study also analyzes the influence of applied electric and magnetic fields. Solutions for eigenstates are then used to evaluate the linear inter-state light absorption coefficient through the corresponding resonant transition energies and electric dipole matrix moment elements, assuming circular polarization for the incident radiation. Results show that both SOI effects and Zeeman splitting reduce the absorption intensity for the considered transitions compared to the case when these interactions are absent. In addition, the magnitude and position of the resonant peaks have non-monotonic behavior with external magnetic fields. Secondly, we investigate the electronic and optical properties of the electron confined in the quantum ring with a topological defect in the structure; the results show that the crossings in the energy curves as a function of the magnetic field are eliminated, and, therefore, an improvement in transition energies occurs. In addition, the dipole matrix moments present a non-oscillatory behavior compared to the case when a topological defect is not considered.

A theoretical analysis was conducted to examine the electronic and optical properties of a confined electron and a hole in a type-II core-shell spherical quantum dot composed of CdSe/ZnTe and ZnTe/CdSe. The Schrödinger equation for the electron and the hole was numerically solved using COMSOL-Multiphysics software in the 2D axisymmetric module, which employs the finite element method under the effective mass approximation. A Fortran code was utilized to calculate excitonic energy, specifically designed to solve the Coulomb integral. The calculations encompassed variations in the inner radius ($R_1$), as well as variations in the electric ($F_z$) and magnetic (B) fields along the z-axis. The absorption coefficients were determined for transitions between the hole and electron ground states, considering z-polarized incident radiation. Including a magnetic field increases the transition energy, consequently causing the absorption peaks to shift toward the blue region of the spectrum. On the other hand, the electric field decreased the overlap of the electron and hole wavefunctions. As a result, the amplitude of the absorption peaks decreased with an increase in the electric field.

We investigated the impact of a non-resonant intense laser, structural defects, and magnetic fields on the electronic and optical properties of a simple GaAs quantum ring under the inverse quadratic Hellmann potential, using the effective mass and parabolic band approximations. We obtained the energies and wavefunctions by solving the 2D Schrodinger’s equation using the finite-element numerical technique to analyze this. We considered circular polarization to calculate the dipole matrix elements, which were influenced by the laser field and structural defects in the system. This enabled us to study the linear absorption coefficients. Our results demonstrated that the presence of a laser field and a structural defect disrupt the axial symmetry of the problem. When only the non-resonant laser was present, a pattern of excited states appeared in pairs, which oscillated with the magnetic field. However, the amplitude of the oscillation decreased as the magnetic field strength increased, and these oscillations disappeared when the structural defect was introduced. It was also noted that the intensity and position of the linear optical absorption peaks exhibited a non-monotonic behavior with the magnetic field in the absence of a structural defect. However, this behavior changed when the structural defect was present, depending on the type of polarization (right or left circular). Finally, a clear improvement in the absorption peaks with an increase in the laser parameter is reported.

Taking into consideration the research that has been conducted on the optical and electrical properties of molecular systems, especially the good thermoelectric energy conversion at a nanometric scale that such systems have presented, here we present a new alternative by using a particular diphenyl-ether molecule as a functional device. Such a molecular system is modeled as a planar segment coupled to two electrodes in the first-neighbor approximation within a tight-binding Hamiltonian. We study the electrical and thermal properties of diphenyl-ether molecules such as the electric current, electrical and thermal conductance, Seebeck coefficient, and figure of merit, in the strong and weak coupling regimes, considering different structural configurations and variations with temperature. Our results could be valuable for laboratory applications and/or verification since we characterize the diphenyl-ether molecule as a semiconductor device for different structural models.