Carbon nanotubes (CNTs) are amongst the most explored one-dimensional nanostructures and have attracted tremendous interest from fundamental science technological perspectives. Albeit topologically simple, they exhibit a rich variety of intriguing electronic properties, such as metallic semiconducting behaviour. Furthermore, these structures atomically precise, meaning that each carbon atom is still three-fold coordinated without any dangling bonds. CNTs been used in many laboratories to...

Quantization in the inversion layer and phase coherent transport are anticipated to have significant impact on device performance “ballistic” nanoscale transistors. While role of some quantum effects been analyzed qualitatively using simple one-dimensional ballistic models, two-dimensional (2D) mechanical simulation is important for quantitative results. In this paper, we present a framework 2D nanotransistor/metal oxide field effect transistor. This consists nonequilibrium Green’s function...

We use a simple picture based on the $\ensuremath{\pi}$ electron approximation to study band-gap variation of carbon nanotubes with uniaxial and torsional strain. find (i) that magnitude slope band gap versus strain has an almost universal behavior depends chiral angle, (ii) sign value $(n\ensuremath{-}m)\mathrm{mod}3,$ (iii) novel change in arising from quantum number corresponding minimum gap. Four orbital calculations are also presented show results valid.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We aim to provide engineers with an introduction the nonequilibrium Green's function (NEGF) approach, which is a powerful conceptual tool and practical analysis method treat nanoscale electronic devices quantum mechanical atomistic effects. first review basis for traditional, semiclassical description of carriers that has served device more than 50 years. then describe why this traditional...

Using a scattering theory approach we study the zero-frequency current fluctuations of normal terminals phase-coherent mesoscopic structure with superconducting region. We find that for devices where potential region is externally fixed (Fig. 1), expression simple generalization corresponding obtained in Buttiker [Phys Rev. B 46, 12 485 (1992)] purely systems. In contrast to systems, between two different contacts can be positive these devices. apply this formula derive shot noise (NS)...

Atomistic simulations using a combination of classical force field and density-functional theory (DFT) show that carbon atoms remain essentially sp(2) coordinated in either bent tubes or pushed by an atomically sharp atomic-force microscope (AFM) tip. Subsequent Green's-function-based transport calculations reveal for armchair there is no significant drop conductance, while zigzag the conductance can several orders magnitude AFM-pushed tubes. The effect be attributed to simple stretching...

We model the influence of scattering along channel and extension regions dual gate nanotransistors. It is found that reduction in drain current due to right half comparable left channel, when length length. This contrast a popular belief source end nanotransistor significantly more detrimental drive than elsewhere. As becomes much larger length, drain-end less near source-end channel. Finally, we show for nanotransistors, classical picture modeling as simple series resistances not valid.

We present the detailed treatment of dissipative quantum transport in carbon nanotube field-effect transistors (CNTFETs) using non-equilibrium Green's function formalism. The effect phonon scattering on device characteristics CNTFETs is explored extensive numerical simulation. Both intra-valley and inter-valley mediated by acoustic (AP), optical (OP), radial breathing mode (RBM) phonons are treated. Realistic dispersion calculations performed force-constant methods, electron-phonon coupling...

This work computationally investigates the electromechanical properties of hydrogen passivated silicon nanowires under uniaxial tensile strain. It has been observed that bandgap changes can be as large 60 and 100 meV per 1% axial strain for [100] [110] nanowires, respectively. rate change in is independent nanowire size depends only on growth direction. More importantly, nature reversibly from indirect to direct a function also larger diameter indirect-to-direct transition occurs at smaller...

Silicon nanowires can enhance broadband optical absorption and reduce radial carrier collection distances in solar cell devices. Arrays of disordered grown by vapor-liquid-solid method are attractive because they be on low-cost substrates such as glass large area compatible. Here, we experimentally demonstrate that an array silicon surrounded a thin transparent conductive oxide has both low diffuse specular reflection with total values < 4% over broad wavelength range 400 nm λ 650 nm. These...

Proton conduction is essential in biological systems. Oxidative phosphorylation mitochondria, proton pumping bacteriorhodopsin and uncoupling membrane potentials by the antibiotic Gramicidin are examples. In these systems, H+ hop along chains of hydrogen bonds between water molecules hydrophilic residues – wires. These wires also support transport OH− as holes. Discriminating has been elusive. Here, achieved polysaccharide- based devices. A H+- junction with rectifying behaviour H+-type...

We analyze the impacts of electric field on Dzyaloshinskii-Moriya interaction, magnetocrystalline anisotropy, and intrinsic ferromagnetism recently discovered two-dimensional ferromagnetic chromium tri-iodide ($\mathrm{Cr}{\mathrm{I}}_{3}$) monolayer, by combining density functional theory Monte Carlo simulations. By taking advantage counterbalancing effects anisotropic symmetric exchange energy antisymmetric energy, it is shown that can be manipulated externally applied off-plane fields....

Abstract DNA is a promising molecule for applications in molecular electronics because of its unique electronic and self-assembly properties. Here we report that the conductance duplexes increases by approximately one order magnitude when conformation changed from B-form to A-form. This large increase fully reversible, controlling chemical environment, can be repeatedly switched between two values. The conformations displays weak length dependencies, as expected guanine-rich sequences, fit...

We study the conductance of carbon nanotube wires in presence disorder, limit phase coherent transport. For this purpose, we have developed a simple numerical procedure to compute transmission through nanotubes and related structures. Two models disorder are considered, weak uniform isolated strong scatterers. In case our simulations show that is not significantly affected by when Fermi energy close band center. Further, around center depends on diameter these zero bandgap wires. also find...

In this paper, we present a full 3-D real-space quantum-transport simulator based on the Green's function formalism developed to study nonperturbative effects in ballistic nanotransistors. The nonequilibrium Green (NEGF) equations effective mass approximation are discretized using control-volume approach and solved self-consistently with Poisson equation order obtain electron current densities. An efficient recursive algorithm is used avoid computation of matrix. This algorithm,...

The optical absorption in a nanowire heterostructure consisting of crystalline silicon core surrounded by conformal shell amorphous is studied. We show that they exhibit extremely high 95% at short wavelengths (λ < 550 nm) and concomitant very low down to less than 2% long > 780 nm). These results indicate our nanowires do not have optically active energy levels the band gap. edge arrays observed shift longer as function overall diameter. near-infrared array significantly better thin film...

Single-wall carbon nanotube (SWNT) bends, with diameters from \ensuremath{\sim}1.0 to 2.5 nm and bend angles 18\ifmmode^\circ\else\textdegree\fi{} 34\ifmmode^\circ\else\textdegree\fi{}, are observed in catalytic decomposition of hydrocarbons at 600--1200 \ifmmode^\circ\else\textdegree\fi{}C. An algorithm using molecular dynamics (MD) simulation techniques is developed model these structures that considered be SWNT junctions formed by topological defects (i.e., pentagon-heptagon pairs). The...

We computationally study the electrostatic potential profile and current carrying capacity of carbon nanotubes as a function length diameter. Our is based on solving non equilibrium Green's Poisson equations self-consistently, including effect electron-phonon scattering. A transition from ballistic to diffusive regime electron transport with increase applied bias manifested by qualitative changes in profiles, differential conductance electric field nanotube. In low limit, most voltage drop...

Recently, there have been a number of interesting experiments on the ac response mesoscopic systems. An important question in this context concerns characteristic frequency at which conductance deviates from dc value. Depending system under consideration, is determined by following three parameters: inverse average time an electron spends inside device, thermal frequency, and phase-breaking time. The theoretical work area has largely based scattering formulation, neglects processes. purpose...

We develop an approach to derive single-state tight-binding (SSTB) model for electron transport in the vicinity of valence-conduction bands $\text{poly}(G)\text{\ensuremath{-}}\text{poly}(C)$ and $\text{poly}(A)\text{\ensuremath{-}}\text{poly}(T)$ DNA. The SSTB parameters are derived from first principles used charge through finite length investigate rigor reducing full DNA Hamiltonian model. While transmission coefficient spectrum is preserved, its position shifts energy. Thymine poorly...

Utilizing sp3d5s* tight-binding band structure and wave functions for electrons holes we show that acoustic phonon limited hole mobility in [110] grown silicon nanowires (SiNWs) is greater than electron mobility. The room temperature acoustically the SiNWs considered can be as high 2500 cm2/V s, which nearly three times larger bulk It also shown exceed those of similar diameter [100] SiNWs, with 2 orders magnitude difference Since small have been seen to grow primarily along direction,...

Biological membrane channels mediate information exchange between cells and facilitate molecular recognition. While tuning the shape function of for precision sensing via de-novo routes is complex, an even more significant challenge interfacing with electronic devices signal readout, which results in low efficiency transfer - one major barriers to continued development high-performance bioelectronic devices. To this end, we integrate spanning DNA nanopores bioprotonic contacts create...