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Öğe Computation of the near-infrared electro-absorption in GeSn/ SiGeSn step quantum wells(Academic Press Ltd- Elsevier Science Ltd, 2024) Yahyaoui, N.; Jellouli, E.; Başer, Pınar; Zeiri, N.; Said, M.; Murshed, Mohammad N.In this study, we propose a theoretical simulation of the type-I step quantum well obtained from GeSn/SiGeSn to scan a wide range of telecommunication wavelengths and obtain near-infrared optical modulators. At T = 300 K, the band discontinuities and energy gap between stretched Ge1_xSnx and relaxed Si0.1Ge0.9_ySny due to the acquisition of the heterostructure were calculated. Then, optimization of this heterostructure based on (Si) GeSn was performed using the solid theory model to balance out the composition y of Si0.1Ge0.9-ySny relaxed and thickness of Ge0.91Sn0.09 QWs. The eigenenergies and their related wavefunctions are computed by solving the Schrodinger equation using the finite difference method under the framework of the effective mass approximation. Depending on the y concentration, the energy levels of the electron and the heavy hole, the change of transition energies and oscillator strength were examined for different well widths. Additionally, the absorption coefficient with y concentration and structure parameters were examined. From the findings obtained, it was determined that this material group is very important to obtain high efficiency from electro-absorption modulators covering the 1.55 mu m wavelength range.Öğe Machine learning algorithms for predicting the photoionization cross section of CdS/ZnSe core/shell spherical quantum dots surrounded by dielectric matrices(Elsevier B.V., 2025) Cherni, A.; Zeiri, N.; Yahyaoui, N.; Baser, P.; Said, M.; Saadaoui, S.; Murshed, Mohammad N.In this study, we explore the prediction of the photoionization cross section (PCS) of CdS/ZnSe core/shell spherical quantum dots (CSQD) surrounded by different dielectric matrices. The quantum dot systems, embedded in polyvinyl alcohol (PVA), polyvinyl chloride (PVC), and silicon dioxide (SiO2) matrices, were modeled under varying core-shell dimensions and dielectric environments. Our findings show that the resonant peak of the PCS experience a redshift with improvement in their amplitude in the case of the PVA matrix, while in the case of the PVC and SiO2 the magnitude of the PCS is reduced and their resonant peak suffers a blueshift. Three different machine learning algorithms were used to estimate the photoionization cross-section, namely Artificial Neural Networks (ANN), Decision Trees (DT), and Random Forest Regressors (RFR). Among these, Random Forest Regression proved to be the most successful algorithm, particularly for the SiO2 matrix, achieving exceptional performance with the coefficient of determination R2 = 0.999 Mean Squared Error MSE=10-4 and the Root Mean Squared Error RMSE=0.0077. While DT exhibited lower MSE, MAE, and RMSE than ANN in the SiO2 matrix, ANN showed potential in capturing more complex nonlinear relationships. These results demonstrate the superior predictive capabilities of RFR and highlight the applicability of machine learning in modeling quantum dot systems. This work offers valuable insights into the optimization of optoelectronic device design through accurate and efficient computational methods. © 2025 The Author(s)Öğe Retraction notice to “The combined effects of electric field and embedded dielectric matrix on the electronic and optical properties in Ge/SiGe core/shell quantum dots and its SiGe/Ge inverted structure” [Physics Letters A (2024) 129760] (Physics Letters A (2024) 523, (S0375960124004547), (10.1016/j.physleta.2024.129760))(Elsevier B.V., 2025) Hammouda, K.; Yahyaoui, N.; Zeiri, N.; Baser, P.; Duque, C.A.; Murshed, Mohammad N.; Said, M.This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of the Editor. Post-publication, it came to the attention of the journal that the authors did not obtain the necessary approval from the journal editor for the addition of a new author and a change to the author order, which is contrary to the journal policy on changes to authorship. In addition, the newly added author (Dr. C.A. Duque) had been suggested as a reviewer by the authors at the submission stage. The editor reached out to the authors for an explanation to the above points, but they failed to provide a satisfactory explanation. Overall, the editor believes that adding a new author at the revision stage without obtaining the necessary approval from the journal editor is contrary to the journal policies and decided to retract the paper. © 2025 Elsevier B.V.Öğe The combined effects of electric field and embedded dielectric matrix on the electronic and optical properties in Ge/SiGe core/shell quantum dots and its SiGe/Ge inverted structure(Elsevier, 2024) Hammouda, K.; Yahyaoui, N.; Zeiri, N.; Başer, Pınar; Duque, C. A.; Murshed, Mohammad N.; Said, M.In this study, the binding energy (BE) and photoionization cross-section (PICS) coefficients in a Ge/Si0.15Ge 0.85 core/shell quantum dots (CSQDs) and in its inverted structure Si0.15Ge0.85 / Ge (ICSQDs) are studied. The influence of the hydrogenic impurity and capped matrix are taken into account. The electronic states and their related eigenfunctions are computed by solving the three-dimensional Schrodinger equation under the framework of the effective mass approximation (E.M.A) using the variational dimensional. The influence of the core radius and electric field strength on the BE and PICS are investigated. The numerical results reveal that the optoelectronic properties are considerably affected by the electric field strength (EF), immersed oxide matrix (OM) and geometric parameter. The obtained results prove that the PICS magnitude increases as the core radius increases and its resonant peak moves towards the lower energies for Ge/Si0.15Ge0.85 CSQDs structure, and increases as the core radius decreases and its resonant peak experiences a blue shift with increasing core radius for Si0.15Ge 0.85/ Ge ICSQDs. Moreover, with the effects of the surrounding oxide matrix and electric field strength, the PICS magnitude is improved and their resonant peak suffers a redshift.Öğe Theoretical investigation of optoelectronic properties in PbS/CdS core/shell spherical quantum dots under the effect of the electric field intensity, hydrogenic impurity and geometric parameters(Springer, 2024) Jellouli, E.; Zeiri, N.; Başer, Pınar; Yahyaoui, N.; Ed-Dahmouny, A.; Murshed, Mohammad N.; Said, M.In this paper, we theoretically investigated the combined effects of the external electric field (EF) strength and the geometric parameters on the linear, nonlinear and total dielectric functions as well as the effective dielectric function (DF) coefficients of PbS/CdS spherical core/shell quantum dots (CSQD) in the presence of the hydrogenic impurity located at the center. The subband energy eigenvalues and their corresponding wave functions are obtained by solving the time-independent Schr & ouml;dinger equation and using the variational method (VM) in the framework of the effective mass approximation (EMA). The linear, nonlinear and total DF as well as the effective DF were discussed and evaluated under the influence of EF intensity, geometric parameters, the change of the number of quantum dots (QDs) per unit volume and optical intensity I based on the compact density matrix (CDM) approach. The obtained results show that the height peaks of the linear, nonlinear and Total DF as well as the effective DF coefficients increase and their resonant peak moves towards lower energies as the EF and geometric factors increase in both cases with and without considering the hydrogenic impurity effect. Furthermore, our findings show that the impact of optical intensity and the number of QDs per unit volume does not change the resonance peaks of imaginary parts of DF and effective DF but decreases their magnitudes. As a result, we believe that numerical results will present important developments and provide great contributions in designing new optoelectronic devices related to CSQD hetero-nanostructure.
