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    Electronic transmission and conductance oscillations in electrostatic multibarrier system based on graphene monolayer
    (Iop Publishing Ltd, 2023) Alsalmi, Omar H.; Dakhlaoui, Hassen; Belhadj, Walid; Ungan, Fatih
    The Landauer-Buttiker formalism and the transfer matrix method (TMM) were used to solve the Dirac equation to theoretically explore the transmission coefficient and the conductance of multibarrier graphene systems (MGS). We have addressed the impact of the number of barriers, angle of incidence, and the quantum size of different layers on the electronic properties. The obtained results show that the conductance and the transmission of the carriers can be readily modulated by increasing the number of barriers. It has been observed that an increase in the number of barriers doubles the number of resonant states which leads to the emergence of energetic minibands alternating with minigaps. Furthermore, we found that after doubling the quantum wells the number of resonant states and minigaps increase and their shapes become well defined. Moreover, we considered two cases of incidence (oblique and normal). In the normal incidence case, the structures were completely transparent for different sizes and incident energy values. However, for high angles of incidence, the transmission coefficient presented sharper resonant peaks separated by minigaps. Thereby, according to our theoretical investigations, such structures can be useful for modulating the electronic properties of devices based on electrostatic MGS.
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    Impacts of electric and magnetic fields on the optical and electronic characteristics of graphene- based multibarrier structure
    (Springer, 2023) Belhadj, Walid; Dakhlaoui, Hassen; Alsalmi, Omar H.; Ungan, Fatih
    The conductance and electronic transmission of Dirac electrons and holes across multibarrier Cantor-like graphene are investigated using on the transfer matrix method and Landauer-Buttiker formalism. Electric and magnetic fields are applied to the top of a monolayer graphene to generate multiple electromagnetic barriers separated by quantum wells. The impact of the magnetic and electric fields as well as the quantum size on the behavior of the transmission coefficient and conductance is discussed. The results indicate that the transmission coefficients exhibit oscillations indicating the existence of resonant states in miniband energies separated by minigap energies. This phenomenon known as the bifurcation process is more pronounced for a higher number of barriers. The behavior observed in the conductance variation reflects of the transmission coefficient especially for lower energies. Furthermore, the contour plot of the transmission coefficient shows the predominant impact of the incidence angle on the symmetry of the minigaps and minibands. These results are expected to be beneficial for experiments that improve the performance of new generations of devices based on multibarrier Cantor-like graphene systems.