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Öğe Effects of external fields and structural parameters on third harmonic generation of GaAs/AlGaAs Manning-like double quantum well structure(Springer Heidelberg, 2024) Tuzemen, A. TurkerIn this theoretical work, we investigate how external fields like as electric, magnetic, and intense laser fields, as well as structural factors, affect the third harmonic generation (THG) coefficient of an AlGaAs/GaAs Manning-like double quantum well heterostructure. To achieve our goals, we numerically solve the time-independent Schr & ouml;dinger equation using the diagonalization approach with the effective mass approximation and then derive the subband energy levels and corresponding wave functions of the structure. After that, we derive the mathematical expression of the THG coefficient by using the compact density matrix method. According to our results, the resonance peaks of the THG coefficient show shifting to the high-energy region with an increase in the field's magnitude in cases where external fields (electric, magnetic, and intense laser) are applied separately. At the same time, increasing the depth (width) of the quantum well structure causes the THG peaks to shift to the high (low) energy region. We believe that the findings from this search will have a substantial impact on existing experimental device designs and applications.Öğe Effects of hydrostatic pressure, temperature, and position-dependent mass on the nonlinear optical properties of triple delta-doped GaAs quantum well(Springer Heidelberg, 2024) Tuzemen, A. Turker; Al, E. B.; Sayrac, H.; Dakhlaoui, H.; Mora-Ramos, M. E.; Ungan, F.In this study, we thoroughly investigate the impacts of hydrostatic pressure, temperature, and position-dependent mass (PDM) on the nonlinear optical properties of asymmetric triple delta-doped GaAs quantum wells. Our analysis covers total optical absorption coefficients, relative refractive index changes, nonlinear optical rectification, second harmonic generation, and third harmonic generation. Initially, we employ PDM to solve the time-independent Schr & ouml;dinger equation using the diagonalization method under effective mass and parabolic band approaches, considering pressure and temperature dependencies. Utilizing the first four energy eigenvalues and eigenfunctions, we apply the compact density matrix method to compute the system's nonlinear optical properties numerically. The results indicate a shift in optical property peak positions toward lower (higher) energy spectra with increasing hydrostatic pressure (temperature). Furthermore, the influence of PDM shifts the system's optical properties toward the higher energy spectrum, resembling the effect of temperature. From an experimental and theoretical perspective, one of the topics that researchers work on most is GaAs-based delta-doped systems (delta-doped heterojunction bipolar transistors, delta-doped field effect transistors, delta-multiple independent gate field effect transistors, etc.). We believe these findings will provide valuable insights for the researchers involved in GaAs-based delta-doped optoelectronic device design.Öğe Investigation of Equilibration and Growth of Stepped Surfaces by Kinetic Monte Carlo in one Dimension(AMER INST PHYSICS, 2017) Turkan, A.; Esen, M.; Tuzemen, A. Turker; Ozdemir, M.; Akkus, B; Oktem, Y; Dogan, GS; Guzelcimen, FIn this study, the equilibration and in the case of a particle flux to the surface, the growth of a one dimensional semiconductor surface of "V" initial shape is investigated by kinetic Monte Carlo method. The initial surface is assumed to consist of atomic height steps separated by terraces. In Monte Carlo simulations, the following processes are considered: the diffusion of free particles on the surface, the attachment/detachment of particles to/from step edges from/to a terrace in front of a step or to a terrace above the step, In the simulations the Ehrlich-Schwoebel barrier is also taken into account. The equilibration of "V" initial shape at various temperatures is investigated, Moreover, the effect of particle bonding energy on the surface profile and on the evolution of the surface is also investigated. In the case of a particle flux to the surface, the surface profile and its growth kinetics are investigated at various temperatures and flux values.Öğe Modeling and simulation of the influence of quantum dots density on solar cell properties(Springer Heidelberg, 2023) Jaouane, M.; Fakkahi, A.; Ed-Dahmouny, A.; El-Bakkari, K.; Tuzemen, A. Turker; Arraoui, R.; Sali, A.Based on the finite element method using the FEniCS computing platform and python programming, we solve the Schrodinger equation within the effective mass approximation. Its solution gives us the necessary energy for an electron to transit from an intermediate band to a conduction band, as well as the distribution of probability density within the system. In this work, we have investigated the efficiency of the InAs/GaAs pyramid quantum dot intermediate band solar cell (PQD-IBSC) as a function of the structure parameters and quantum dot density. The simulation results indicated the strong dependence of the efficiency of PQD-IBSC on the confinement effect, quantum dot number or quantum dot density and coupling strength. The conversion efficiency grows from 14.4587% to the optimal efficiency 17.8807%. Generally, the best efficiency is obtained for small barrier width, large quantum dot height and great quantum dot density.Öğe Nonlinear optical properties of GaAs/AlGaAs asymmetric triple quantum wells designed for quantum cascade lasers: Effect of externally applied electric and magnetic fields(Elsevier, 2024) Tuzemen, A. Turker; Dakhlaoui, H.; Mora-Ramos, M. E.; Al, E. B.; Ungan, F.We explore the impact of external fields on the absorption coefficients and relative refractive index changes in a quantum cascade laser profile-like heterostructure that consists of a triple asymmetric quantum well. Firstly, we solve numerically the time -independent Schro dinger equation by using the diagonalization method under the effective mass and parabolic band approaches, to obtain the energy levels and wavefunctions. Then, we evaluate the optical coefficients from the analytical expressions derived from the compact density matrix method. The obtained results put forth that the resonant peaks of optical coefficients shift to higher (lower) energies by increasing the value of the electric (magnetic) field. These results indicate that it would be possible to adjust the optical properties of these structures to the desired range with external fields. As a result, we hope that new optoelectronic devices based on asymmetric triple quantum wells can be developed using the features found here.Öğe Second harmonic generation in Harmonic-Gaussian asymmetric double quantum well: effect of magnetic and intense laser fields(Iop Publishing Ltd, 2024) Tuzemen, A. Turker; Demir, M.; Dakhlaoui, H.; Mora-Ramos, M. E.; Ungan, F.We have theoretically analyzed the effects of externally applied fields (magnetic and intense laser) as well as various structural parameters such as well width, barrier width, barrier height, and structural asymmetry on the second harmonic generation (SHG) coefficients of GaAs/Al0.3Ga0.7As Harmonic-Gaussian asymmetric double quantum wells (QW). The time-independent Schr & ouml;dinger equation was solved using the diagonalization method and effective mass approximation to obtain the energy eigenvalues and eigenfunctions of the structure. An expression derived within the compact density matrix approach has been used to evaluate the second harmonic generation (SHG) coefficient. Our numerical results indicate that increasing the magnitude of the magnetic (intense laser) field causes the peak positions of SHG to shift towards higher energy regions/blue (lower energy regions/red). On the other hand, as the structural parameters A 1 and A 2 ( k and z 0 ) increase, the peak positions of the SHG coefficients exhibit a shift towards higher energy regions/blue (lower energy regions/red). We expect that the results of our study will contribute to the development of new optoelectronic devices based on the Harmonic-Gaussian asymmetric double quantum well structure.Öğe Thermodynamic properties of a Gaussian quantum ring in the presence of a molecular ion(Springer Heidelberg, 2025) Sakiroglu, S.; Tuzemen, A. Turker; Turk, G. Eyceyurt; Sari, H.In this study, the findings of research conducted into the thermodynamic properties of a molecular complex ion in a 2D quantum ring characterized by Gaussian-type potentials are presented. The Schr & ouml;dinger equation for a singly ionized double donor complex was solved by a two-dimensional diagonalization method. The results obtained show that at the internuclear distance, where there is coupling between the Coulomb centers such that the electron is shared by both impurity atoms, the mean energy and entropy of the system are minimal. A further finding is that in the regime where the distance between impurity atoms is comparable to the inner radius of the quantum ring, the heat capacity of the system undergoes significant changes with temperature.
