We investigate electron transport properties in a deformed (8, 0) silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two-probe molecular junction constructed from deformed nanotube. The results suggest significant reduction in threshold voltage in the case of both radially compressed and axially elongated (8, 0) SiCNTs, a large difference in current–voltage characteristics was observed. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show bandgap reduction in deformed nanotubes. Deformation introduces electronic states near the Fermi level, enhancing the conduction properties of (8, 0) SiCNT. The FMOs and the orbitals corresponding to peaks in 𝑇(𝐸) around Fermi level obviously has some major contributions from the deformed site. However, localization of the electronic state near the Fermi level is weak in (8, 0) SiCNT, possibly because of its large bandgap.

The effect of tailoring the graphene sheets used as channel in a graphene nanoribbon field effect transistor (GNRFET) was investigated. The study was performed using self-consistent solution of Poisson's and Schrodinger's equation in combination with non-equilibrium Green's function (NEGF) formalism. Graphene sheet channel was tailored into different shapes and found that with the introduction of edge roughness along the border of GNR sheet the bandgap of GNRFET channel increases. Tailoring the channel decreases mobility and transmission probability to a great extent and thus the performance of I–V characteristics of GNRFET degrades.

In this paper, device performance of graphene nanoribbon field effect transistor (GNRFET) with different doping concentrations in different parts of the channel is reported. The study is performed by using atomistic simulations based on self-consistent solution of Schrodinger’s and Poisson’s equation within the non-equilibrium Green’s function formalism. The transfer and output characteristics suggest that device performance with $n$-type doping in the channel is better with smaller supply voltage compared to higher supply voltage. On increasing the $n$-type doping concentration, we obtained better on-current and output characteristics in comparison with undoped and $p$-type doped channel GNRFET. Further, we introduced step-doping profile in the graphene nanoribbon (GNR) channel and found that the device gives better on-current and good saturation condition when compared to undoped or uniformly-doped channel.

Electronic and optical properties of pristine and metal-doped lithium niobate crystals are investigated by using first-principles DFT calculations. The results on optical properties suggest that there is a shift in the absorption edge towards visible region (red-shift) for metal-doped structures, in comparison with the pristine lithium niobite. A series of metals are used for doping and it is found that the absorption edge is shifted significantly to the visible region for the dopants; gold (Au), silver (Ag), aluminium (Al) and copper (Cu) due to surface plasma resonance. However, for other metal dopants like iron (Fe), manganese (Mn), molybdenum (Mo) and nickel (Ni), the absorption is slightly improved in the visible region and red-shift is observed. The bandgap of all the doped structures is found to be reduced, this might be proven advantageous for photovoltaic applications, which requires high optical absorption in the visible region. The dielectric constant and refractive index of the pristine and doped structures are also calculated and it is observed that the absorption trend is in accordance with dielectric constant. The optical absorption is enhanced in the visible region due to doping of selected metals (M = Au, Ag, Al, Cu, Fe, Mn, Mo and Ni) making M-lithium niobite a promising material for optoelectronic- and photonic-based applications.