جستجوی مقالات مرتبط با کلیدواژه « نانونوار » در نشریات گروه « فیزیک »

Arsenene is one of the members of a large group of two-dimensional structures that in the present project, we have investigated the single layer structure and its nanoribbons based on density functional theory. In this study, after calculating the single layer band structure, we discussed the effect of width on the band structure of nanoribbon from the angle of quantum limiting phenomenon. The results show the different effect of quantum limiting phenomenon on different points of each band in the band structure, which is the cause of indirect-direct gap transition due to the reduction of the width of armchair nanoribbon. Also, the electrical conductance properties of arsenene single layer have been obtained by calculating the mobility of load carriers and the effect of uniaxial strain of crystalline structure on them has been investigated. In order to investigate the mobility, crystalline structure defects have been neglected and only phonon dispersion is considered based on Takagi relationship. In this process, the focus is not on the quantitative accuracy of the obtained values for the mobility of load carriers and the existing anisotropy between mobility in the two directions of armchair and zigzag has been the focus of the discussion. The results of the calculations show a significant anisotropy of mobility in the two directions of armchair and zigzag and the effect of uniaxial strain of crystal structure on it. Also, a significant difference between the mobility of electrons and holes in the direction of armchair is one of the key results.

So far, most of researches and investigations have been based on absorption and surface plasmon waves propagation on graphene and its various realized patterns mounted over isotropic substrates. In this paper, at first the structure of graphene over hexagonal boron nitride, as an anisotropic substrate, its effective permittivity and reflection coefficient, and also, the possibility of their tuning through change in graphene Fermi level, is studied. Then, characteristics of surface plasmon waves propagation on graphene nano-ribbons mounted over uniaxial anisotropic substrate are investigated analytically and numerically. Employing such substrates can decrease propagation loss in comparison with other substrates dramatically. The results of this investigation can be utilized in analysis of absorbers and periodic arrays of graphene nano-ribbon over hexagonal boron nitride substrates.

In this paper, we study the electronic conductance of a nanoribbon with square lattice by using Green’s function theory within the tight-binding approach. For this purpose, we separate the conductance modes in the ideal parts by using a suitable unitary transformation in order to obtain the analytic formula for the corresponding self-energies. Then, we present a fast computer algorithm based on the Fisher-Lee formula for the calculation of the system conductance. The results show that the distribution of electrical impurities with different on-site energies leads to the different values of the system electronic conductance and it is generally decreasing.

The structural and electronic properties of the hydrogenated zigzag GaN nanoribbons with different widths 19.2, 24.85, 30.49 and 36.14 Å corresponding to numbers of the zigzag chain, 3, 5, 7, 9, have been studied. Density functional theory with full potential augmented plane wave approach and the generalized gradient approximation (GGA) are used for exchange-correlation functional. The curves of total and partial density of states and electronic density of the nanoribbons were drawn. These computations show that all of the nanoribbons have semiconducting behavior. Values of energy gap of the nanoribbons are 2.687 eV, 2.304 eV, 2.107 eV and 2.008 eV for the ribbons with 3, 5, 7 and 9 width, respectively. With increasing the width of the nanoribbons, the band gap is decreased. Also, these nanoribbons do not have magnetic property. In addition, in narrower ribbon, the partial density of states shows that the edge atoms have more constitution than that of inner atoms in density of states.