Elmustapha Feddi

• Professor at Mohammed V University

We study electron scattering in graphene quantum dots (GQDs) under the combined influence of a magnetic field, an energy gap, and circularly polarized laser irradiation. Using the Floquet approach and the Dirac equation, we derive the energy spectrum solutions. The scattering coefficients are calculated explicitly by matching the eigenspinors at th...

Optimizing the parameters that control the InAsP/InP quantum well (QW) system is of utmost importance for this system to give the best yield. Beginning from QW energy levels and momentum matrix element calculation, this work studies linear, nonlinear absorption and refractive index change, second harmonic generation (SHG), and third-harmonic genera...

In this work, the patterns of changes in concentration, density of thermodynamic states, thermodynamic potential, entropy and heat capacity of electron gas under the influence of hydrostatic pressure and temperature were studied in nanowires in the form of a rectangular potential well, obtained on the basis of semiconductors with narrow bandgaps. T...

The bound-state solution of the radial Klein-Gordon equation has been obtained under the interaction of an exponential-type and Yukawa potential functions. The Greene-Aldrich approximation has been used to overcome the centrifugal barrier and enable the analytical solutions of the energy and wave functions in closed form. The momentum space wave fu...

In this theoretical study, we investigate optical properties of a hollow cylindrical quantum wire in the presence of a homogeneous magnetic field. The magnetic field is applied parallel to the axis of the quantum wire. The investigations were achieved by solving the Schrödinger equation within the effective mass approximation. The optical propertie...

In this research, the energy equation of the Schrodinger equation with the modified Scarf potential has been obtained using the supersymmetric WKB(SWKB) approach.ThePekeris approximation has been applied to enable the analytical solution. The energy equation was applied to determine the rovibrational states of two diatomic molecules such as O+ 2(X2...

In this research, electron energy levels were calculated analytically using Nelson’s formula, the shooting method, and Garrett’s formula for effective mass. These calculations were performed for a rectangular finite deep potential well, focusing on the InP/InAs/InP heterostructure, which is a narrow-bandgap semiconductor system. Our results demonst...

The main purpose of this work is studying the linear Susceptibility in the hybrid nanostructure that composed of a dual quantum dot (DQD) and metal nanoparticle (MNP) hybrid system under a standing-wave field. In our model, we used density matrix equations by taking into our account the interaction between excitons and surface plasmons. The propose...

The bound-state solution of the Klein-Gordon equation has been obtained under the interaction of an exponential-type and Yukawa potential functions. The Greene-Aldrich approximation has been used to overcome the centrifugal barrier and enable the analytical solutions of the energy and wave functions in closed form. The D-dimensional momentum space...

The thermodynamic and magnetic properties of quantum-dot structures subjected to an applied magnetic field were studied, including the longitudinal optical-phonon interaction and the Rashba spin-orbit effect. The Schrödinger equation was solved to determine the energy levels. The partition function was evaluated by summing the accessible energy lev...

In this theoretical investigation, we delve into the significant effects of donor impurity position within core/shell quantum dot structures: type I (CdTe/ZnS) and type II (CdTe/CdS). The donor impurity’s precise location within both the core and the shell regions is explored to unveil its profound influence on the electronic properties of these na...

Using first-principle calculations, we investigate the impact of strain on the electronic structures and effective masses of Janus WSTe and MoSTe monolayers. The calculations were performed using the QUANTUM-ESPRESSO package, employing the PBE and HSE06 functionals. Our results demonstrate that strain fundamentally changes the electronic structures...

In this study, the structural, electrical, and optical characteristics of the Stannite Cu2CoGeS4 (CCGS) are investigated using first-principle calculations. Band gap energy is determined using both the mBJ + U and HSE potentials. Both methods yield to similar results (1.73 eV and 1.78 eV for the first and second, respectively and 1.78 eV for the fi...

In this work, we present a theoretical study on the use of Cu2ZnSn(S,Se)4 quantum wells in Cu2ZnSnS4 solar cells to enhance device efficiency. The role of different well thickness, number, and S/(S + Se) composition values is evaluated. The physical mechanisms governing the optoelectronic parameters are analyzed. The behavior of solar cells based o...

In the current work, we study the intense laser pulse influences on the behaviors of the first excitonic transition in a core/shell quantum dot submitted to an electric field. Therefore, the exciton binding energy and the mean distance between the correlated electron–hole pair are discussed, considering the electric field and laser strength. Our ca...

Nanomaterials are at the forefront of the fast-paced development of nanotechnology. These materials are outstanding and indispensable in various human activities as long as their size-dependent characteristics. One of the most promising applications of nanomaterials is biomedical. This work reviews the hybrid quantum dot-metal nanoparticle applicat...

In quantum dots, where confinement is strong, interactions between charge carriers play an essential role in the performance of semiconductor materials for optical gain. Therefore, understanding this phenomenon is critical for achieving new devices with enhanced features. In this context, the current study examines the optical properties of an exci...

This study investigates the electronic properties of a single layer of the novel Janus material GeSnS2 using density functional theory. By utilizing the hybrid functional HSE06 in addition to the standard PBE approximation, the study aims to obtain accurate findings about how changes in strain and electric field affect the material's electronic pro...

This study investigates the effect of quantum size and an external magnetic field on the optoelectronic properties of a cylindrical AlxGa1−xAs/GaAs-based core/shell nanowire. We used the one-band effective mass model to describe the Hamiltonian of an interacting electron-donor impurity system and employed two numerical methods to calculate the grou...

We have investigated the effect of temperature and geometrical confinement on the behavior of spherical cavities with Yukawa potential presence inside the cavity within effective mass approximation. Using the Finite-element method, we have calculated the energy eigenvalue with the geometric and temperature effects into consideration with considerat...

Electron states in spheroid \(Si_{0.7}Ge_{0.3}\) quantum dots are investigated taking into account the presence of a donor impurity atom and a weak external electromagnetic laser field. The conduction band confining profile along the radial direction is modelled by a parameterized exponential potential. Based on the calculated inter-state transitio...

Semiconductor core/shell quantum dots represent a promising class of nanostructure that can provide new techniques of control for performing the electronic and optical properties. Through each combination formed by the core and the shell radii and the confinement effect, the trapped charge carries behave differently, which obviously has a direct ef...

The kesterite Cu2ZnGeS4 (CZGS) has recently gained significant interest in the scientific community. In this work, we investigated the thermodynamic and thermoelectric properties of CZGS by employing the first-principals calculation in association with the quasi-harmonic approximation, Boltzmann transport theory, deformation potential theory, and s...

Rashba effect may play an important role in the nonlinear optical properties of heterojunction quantum dots. In this work, we have theoretically examined the effects of Rashba spin-orbit interaction on an electron in a cylindrical core/shell quantum dot (CCSQD). The modifications of various properties of cylindrical core/shell quantum dot such as t...

We theoretically investigate the properties of exciton-polaron moving through a magnetic barrier in monolayers (1Ls) transition metal dichalcogenides (TMDs): MoS2, WS2, MoSe2, and WSe2. We find that the exciton-polaron has the highest ground state energy in WS2 and the lowest one in MoSe2. It is seen that the magnetic barrier stabilizes the exciton...

Photovoltaic cells, based on quantum dots implementation in the intrinsic region, are one of the most widely studied concepts nowadays to obtain a high solar conversion efficiency. The challenge in this third generation of solar cells is to find a good combination of materials that allows obtaining higher efficiency with low cost. In this study, we...

In this paper, first principle calculations of Cu2NiGeS4 (CNGS) are carried out to explore the structural, electronic and optical properties of kesterite compound. Both mBJ+U and HSE potentials are used to calculate the band gap energy. The first approach gives a value of 1.78 eV and the second one a value of 1.76 eV. Our numerical simulation shows...

Using real input parameters from our experimental results of ZnO:Al, ZnS, and CZTS thin films, a numerical simulation using SCAPS-1D (Solar Cells Capacitance Simulator one-dimensional) software has been performed to evaluate the solar cell characteristics by giving the variations of the short-circuit current density (Jsc), the open circuit voltage...

Antimony sulfide selenide (Sb2(S1-xSex)3) material has emerged as a potential candidate for solar cell fabrication. However, up-to-date, efficiencies of about 7% have been widely reported for solar cells based on this absorber material under a p–n junction. Further experimental and theoretical attempts are required to find the main limitations of t...

Magnetic and thermodynamic properties of two electron system confined in 2-D quantum structures submitted to an applied magnetic field are studied taking into account the spin–orbit and electron–phonon interactions. The confinement is considered as a harmonic potential and the electron–electron interaction is taken as coulombic. We have first solve...

Zirconia bulk is one of the most studied materials around the world due to different properties such as a high melting temperature, biocompatibility, and high thermal expansion, among many others. However, there is little experimental research about Zirconia nanowires and until now there are few theoretical papers on the subject. In this work, DFT c...

Following the chronological stages of calculations imposed by the WIEN2K code, we have performed a series of density functional theory calculations, from which we were able to study the effect of strain on the kesterite structures for two quaternary semiconductor compounds Cu2ZnGeS4 and Cu2ZnGeSe4. Remarkable changes were found in the electronic an...

Tin sulfide (SnS) semiconductor has recently attracted a great deal of attention from the scientific community regarding its application in solar cells. However, SnS solar cell efficiencies are still limited to less than 5%. The incorporation of nanostructures into solar cells has been demonstrated to be a potential route to improve device performa...

This theoretical study is devoted to the effects of pressure and temperature on the optoelectronic properties assigned to the first lowest transition of the (D+,X) excitonic complex (exciton-ionized donor) inside a single AlAs/GaAs/AlAs spherical quantum dot. Calculations are performed within the effective mass approximation theory using the variat...

We have studied the parallel and perpendicular electric field effects on the system of SiGe prolate and oblate quantum dots numerically, taking into account the wetting layer and quantum dot size effects. Using the effective-mass approximation in the two bands model, we computationally calculated the extensive variation of dipole matrix (DM) elemen...

Solar cells that are based on the implementation of quantum dots in the intrinsic region, so-called intermediate band solar cells (IBSCs), are among the most widely used concepts nowadays for achieving high solar conversion efficiency. The principal characteristics of such solar cells relate to their ability to absorb low energy photons to excite e...

In this study, the intersubband optical absorption coefficients (OACs) in double-graded quantum wells (QWs) with constant effective mass and position-dependent effective mass (PDEM) are investigated for different applied magnetic field, respectively. The energy levels and the envelope wave functions of an electron confined in finite potential doubl...

Simultaneous effects of electric, magnetic, and non-resonant intense laser field on the nonlinear optical properties of a GaAs quantum well with an anharmonic confinement potential profile are theoretically investigated. Energy eigenvalues and eigenfunctions of the system are determined using the diagonalization method within the framework of the e...

In this work, the influence of biaxial strain on electronic, optical, and effective masses characteristics of Janus MSSe (M = Mo, W) have been investigated through first-principles calculations as implemented in WIEN2k package. From the obtained results, we remark that MoSSe and WSSe monolayers exhibit, respectively, a direct and indirect bandgap t...

New generation of solar cells based on the implementation of quantum dots in the intrinsic region has attracted much attention due to the fact to that it takes advantage of photons with energies lower than the band gap for achieving high solar conversion efficiency. However, there is still a need for optimizing many parameters related to the solar...

It is known that the lines of exciton (X) and exciton trapped by an ionized donor (D + , X) are often very close which makes very difficult their experimental identification. In order to facilitate their distinction in spherical quantum dots, we investigate the effect of an applied magnetic field studying the binding energy of the complex (D + , X)...

Semi oblate and semi prolate are among the most probable self-organized nanostructures shapes. The optoelectronic properties of such nanostructures are not just manipulated with the height and lateral size but also with the wetting layer element. The practical interest of derivatives of germanium and silicon has a great important role in optoelectr...

The electron energy spectrum of a core/shell spherical quantum dot made of zincblende GaN/InN compounds is investigated taking into account the presence of an off-center donor atom and the influence of band nonparabolicity. The interaction of both the charge carrier and the Coulombic core with longitudinal optical phonons is included through Frö hl...

Understanding the behavior of single dopant in semiconductors is a challenge to attain a high control on optoelectronic devices. Based on the fact that the external perturbations have an important impact on properties of doped nanocrystals, we have studied the simultaneous effects of phonons and conduction band non-parabolicity combined to dielectr...

In this work, we investigated the influence of the geometrical confinement effects on the fundamental thermal properties of rutile and anatase TiO2 for both cylindrical nanostructures (CNSs) and nanotubular structures (NTSs), respectively. Calculations of energy levels are developed in the framework of effective mass approximation by generalizing t...

In this work, we investigated the influence of the geometrical confinement effects on the fundamental thermal properties of rutile and anatase TiO 2 for both cylindrical nanostructures (CNSs) and nanotubular structures (NTSs), respectively. Calculations of energy levels are developed in the framework of effective mass approximation by generalizing...

In this work, we investigated the influence of the geometrical confinement effects on the fundamental thermal properties of rutile and anatase TiO2 for both cylindrical nanostructures (CNSs) and nanotubular structures (NTSs), respectively. Calculations of energy levels are developed in the framework of effective mass approximation by generalizing t...

The dense attachment of silver nanoparticles (AgNPs) on indium tin oxide (ITO) surfaces was successfully synthesized and developed using a refined seed-mediated growth approach (RSMG). AgNPs/ITO film prepared was investigated using several methods such as UV-visible spectroscopy, field emission scanning electron microscope, optical absorption, elec...

We provide a comprehensive computational investigation concerning the effects of confinement and temperature on the thermodynamic properties of cylindrical core/shell quantum dots with a large band offset. This model can also be applied to hollow cylindrical quantum dots or nanofibers. Within the framework of the effective mass approximation, we so...

In this paper, we report a recent theoretical study of the calculation of the binding energy and photoionization cross section of a single dopant in a spherical hollow or core/shell quantum dot taking into account the interaction of the electron with longitudinal optical phonons. Using Frolich approach and Lee-low Pines transformation, we determine...

The states of a single dopant centre in zinc-blende GaN-based conical quantum dots with spherical cap are theoretically investigated by analytically solving the corresponding effective mass equation taking advantage of the localisation of the ionised impurity at the cone apex. Nonlinear optical response is analysed through the calculation of the co...

In present work, we theoretically study both the linear and the nonlinear absorption coefficient and refractive index related to the 1s-1p transition of a donor impurity in an AlAs/GaAs cylindrical core-shell quantum dot. Computations were carried out within the effective mass approximation employing a variational approach. It has been observed tha...

The problem of exciton states in spherical semiconductor quantum dots is revisited, employing Q1 the finite element method to numerically solve the system of differential equations for the center of mass and relative motion of the interacting electron-hole pair. This process is performed within the effective mass and parabolic bands approximations....

In this work, we investigate the influence of the internal electric field induced by the polarization inside the active region of the p-i-n photodiode on the characteristics of InN/InxGa1-xN quantum dots intermediate band solar cell. Considering the conduction and valence band offsets, the electron and hole energy levels have been determined by sol...

The properties of the conduction band energy states of an electron interacting with a donor impurity center in spherical sector-shaped GaAs-Al0.3Ga0.7As quantum dots are theoretically investigated. The study is performed within the framework of the effective mass approximation through the numerical solution of the 3D Schrödinger equation for the en...

The polaronic effect on the linear, third-order nonlinear and total optical absorption coefficients have been calculated in the case of GaAs/AlAs core/shell quantum dot, with the impurity is positioned at the central radial position of the GaAs shell. The calculations are realized in the framework of the effective mass approximation and the numeric...

The Schrödinger equation in the effective mass approximation is commonly used to calculate the electronic states confined in low-dimensional semiconductor structures. Three-dimensional calculations are unavoidable in the general case of asymmetrical quantum structures and the solutions are not analytical, thus demanding resource-consuming numerical...

In this paper, we propose the modeling of the two-dimensional electron gas (2DEG) density in InGaN/GaN hetero-interface based high electron mobility transistors (HEMT). The Schrodinger-Poisson equations, as well as the polarization-induced charges, have been utilized. The temperature effect on the effective mass, band gap energy, dielectric constan...

In this paper, we explore the optical properties of AlGaAs/GaAs semi-parabolic quantum well (QW) under different temperature, hydrostatic pressure and applied magnetic field. We calculate the nonlinear optical absorption coefficients and the refractive index changes (RICs) with the compact density-matrix approach and iterative method. Then, within...

Electronic and optical properties of phosphorene quantum dots functionalized with an organic molecule, por-phyrin, are investigated using density functional theory with two different van der Waals functionals. The electronic structure of this complex is obtained and with this information, the real and imaginary parts of the dielec-tric function are...

In the present work, the linear and nonlinear optical absorption coefficients (OACs) and third harmonic generation (THG) in AlGaAs/GaAs single and double triangular quantum wells (TQWs) have been studied, emphasizing on the influence of position dependent effective mass (PDEM) and the shapes of confined potential. We calculate the OACs and THG with...

We theoretically study the combined effect of Al-concentration, hydrostatic pressure, and temperature on the magneto-optical absorption properties of a semi-parabolic quantum well (SPQW) by investigating the magneto-optical absorption coefficient (MOAC) and the full-width at half-maximum (FWHM). The expression of MOAC is expressed by the second-ord...

In the present work, we investigate the electronic and optical properties of few-layer MS 2 (M = Mo, W) and their van der Waals heterostructure MoS 2 /WS 2 using density functional theory. Our calculated results demonstrate that the energy gap of the MS 2 depends tightly on the number of layers. Besides, maximum absorption of the few-layer MS 2 occ...

We investigate the combined effects of hydrostatic pressure, Al-concentration, temperature, and well-width parameter on the magneto-optical absorption properties (MOAPs)of a hyperbolic-type quantum well (HTQW). The results covered all possible processes: both phonon absorption and emission as well as both one- and two-photon. Our results show that...

This work is based on a recent theoretical study of how the hydrostatic pressure and core/shell sizes affect the optical properties associated with the transition from the ground state to first excited state (1s–1p), of an exciton confined in spherical core/shell quantum dots (SCSQDs). We have computed under an effective mass framework, linear, thi...

We report a theoretical investigation of the photovoltaic conversion efficiency of solar cells based on the introduction of In Ga N InN / x x 1 quantum dot supracrystals arrayed in the i-region of a p i n photodiode. The position and width of intermediate bands induced by the discrete quantized energy levels of electrons and holes originating from...

The influences of hydrostatic pressure combined to the size effect on the behavior of the exciton in 2D GaN/AlN quantum ultra‐thin disk, on the binding energy and optical absorption coefficient are investigated. Our approach is performed in the framework of effective mass theory and by using a variational method with a robust trial wave function an...

The impact ionization in semiconductor materials is a process that produces multiple charge carrier pairs from a single excitation. This mechanism constitutes a possible road to increase the efficiency of the p-n and p-i-n solar cells junctions. Our study considers the structure of InN/InGaN quantum dot solar cell in the calculation. In this work,...

The features of the electron energy spectrum in eccentric two-dimensional GaAs-AlGaAs quantum rings of circular shape are theoretically investigated taking into account the effect of externally applied magnetic and intense laser fields. Analytical expressions for the laser-dressed confining potential in this kind of quantum ring geometry are report...

Monoclinic VO 2 is a known polymorph of vanadium dioxide that has received much attention due to its oxidative capabilities, geometric configuration, and promising applications in functional windows. VO 2 can usually be obtained through a hydrothermal method under high pressure. In this work we report a synthesis of VO 2 doped with Manganese using...

In this paper, we investigate the effect of conduction band non-parabolicity (NPBE) on the third harmonic generation(THG), the linear and nonlinear intersub-band optical absorption coefficients (OACs) related with electronic states of double semi-V-shaped GaAs/Ga1−xAlxAs quantum wells(QWs) by using the compact-density-matrix approach. Simultaneousl...

The pressure and temperature effects on the optical responses involving the \(1s-1p\) intersubband transition of an exciton in a spherical quantum dot are investigated. Calculations are performed in the framework of the effective mass approximation and the energies are obtained by using a Ritz variational method. Our approach is based on the Hyller...

This paper reports a recent study on the polarizability and the photoionization cross section (PCS) of a hydrogenic impurity confined in a spherical A l A s / G a A s core/shell quantum dot under external electric field and hydrostatic pressure. In the framework of effective mass theory, a variational approach is used to determine the polarizabilit...

The effect of an applied external electric field on the binding energy of a donor impurity confined in a core/shell quantum dot is investigated taking into account the polarisation, self-polarisation contributions and the core/shell sizes. Calculations are performed in the framework of the effective mass approximation and using the Ritz's variation...

This paper reports the numerical investigation of the quantum confinement effects on excitons in a Si cylindrical core/shell quantum dots. Using the effective-mass approximation and considering a variational technique, we have calculated the exciton ground state binding energy as functions of the shell size in order to study the behavior of the con...

The electronic states in GaAs-AlxGa1-xAs elliptically-shaped quantum rings are theoretically investigated through the numerical solution of the effective mass band equation via the finite element method. The results are obtained for different sizes and geometries, including the possibility of a number of hill-shaped deformations that play the role...

In this paper, we present a theoretical investigation on the polaronic, impurity position and quantum confinement effects on the ground state binding energy of single dopant confined in cubic GaN/InN core/shell quantum dots. Within the framework of the effective mass and non-parabolic approaches, the Schrödinger equation is numerically solved by us...

In this work, we consider the effect of biaxial ɛb and uniaxial ɛac∕zz strains on electronic properties and optical parameters of monolayer SnS using first-principles calculations. Our calculations show that the monolayer SnS is a semiconductor with an indirect energy gap of 1.63 eV at the equilibrium state. While an effect of tensile strains on ba...

Graphene-based van der Waals heterostructures by stacking graphene on other two-dimensional materials have recently attracted much attention due to their extraordinary properties and greatly extend the applications of the parent materials. By means of the density functional theory from first-principles calculations, in this work, the electronic pro...