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In this work, the properties of the photonic bandgap (PBG) and Omni-directional photonic bandgap (Omni-PBG) of a quasi-one-dimensional photonic crystal (PC) are studied, in both TE and TM polarization modes. The PC is made of SiO2 and AlxGa1−xAs layers, alternatively, where x is the content of aluminum atoms in the GaAs slab. Using the transfer matrix method (TMM), the calculations are carried out within Maxwell's equation framework, to express the magnetic field of each medium in terms of electric. This model reduces the numerical calculation time and enables us to investigate the PBG and the Omni-PBG properties in the superlattices. We show that by varying the content and geometrical parameters, one can easily block the transmittance of the electromagnetic wave in the PC. The numerical results may be useful in designing of optical filtering nano-devices.

In this work, we present a detailed investigation of the influences of intrinsic spin-orbit coupling (ISOC) as well as Rashba spin-orbit coupling (RSOC) on the spin-resolved transport properties and net spin polarization of molybdenum disulfide (MoS2) nanoribbons including different configurations. For this reason, we generalize the tight-binding model by including the effects of the ISOC on all the atoms and a RSOC induced by a vertical electric field. The results predict a noticeable spin polarization in along to the field for the armchair MoS2 nanoribbon close to the Fermi level, which is originated mostly from edge states. Where as, the induced spin polarization in the zigzag MoS2 ribbons is much smaller than that of the considered armchair ones. Contrary to the RSOC, which it can not introduce significant spin polarization in the ZMoS2 the ribbon with width about 1–2 nm, the combination effect of an exchange field and Rashba spin-orbit interaction induces a spin-selective current especially close to the Fermi level. The numerical results may be useful to engineer and design magnetic-field-free spintronic devices based on the MoS2 nanoribbons.

In this work, we present a recursive Green’s function method to calculate electronic transport of armchair graphene nanoribbon (AGNR) and zigzag graphene nanoribbons (ZGNRs) quantum wires with randomly adsorption of monatomic gas molecules, which attached to two semi-infinite metallic leads. This model reduces numerical calculations time and enables us to use Green’s function method to investigate transport in a supperlattice device. The calculations based on the Landauer-type formula within the tight-binding approximation, which the recursive Green’s function method is used to solve inhomogeneous differential equations. The effects of monatomic gas molecules adsorption on electronic conductance properties are studied for various length and wide size of wire. Our numerical results show that the transport properties are strongly affected by the quantum interference effect, the lead interface geometry to the device and also adsorption of gas molecules on GNR sheets. By controlling the type of contact and wire geometry, this kind of system can explain the antiresonance states at the Fermi energy. The results can be used to control and engineer the graphene-based systems.

In this work, we study quantum transport properties of a defective graphene nanoribbon (DGNR) attached to two semi-infinite metallic armchair graphene nanoribbon (AGNR) leads. A line of defects is considered in the GNR device with different configurations, which affects on the energy spectrum of the system. The calculations are based on the tight-binding model and Green’s function method, in which localization length of the system is investigated, numerically. By controlling disorder concentration, the extended states can be separated from the localized states in the system. Our results may have important applications for building blocks in the nano-electronic devices based on GNRs.

In this work, we introduce a recursive Green’s function method for investigating electronic transport in a graphene nanoribbons (GNRs) quantum wire with armchair (AGNR) and zigzag (ZGNR) edges which attached to two semi-infinite square lattice leads. This model reduces numerical calculations time and enables us to use Green’s function method to investigate transport in a supperlattice device. Therefore, we consider AGNR and ZGNR devices attached to metallic semi-infinite square lattice leads, taking into account the effects of longitudinal and wide of the wire. Our calculations are based on the tight-binding model, which the recursive Green’s function method is used to solve inhomogeneous differential equations. We concentrate on the electrical conductance and current for various length and wide size of the wire. Our numerical results show that the transport properties are strongly affected by the quantum interference effect and the lead interface geometry to the device. By controlling the type of contact and wire geometry, this kind of system can explain the antiresonance states at the Fermi energy. Our results can serve as a base for developments in designing nano-electronic devices.