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  • Küçük Resim Yok
    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.
  • Küçük Resim
    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.