RESUMEN
Single-wall carbon nanotubes (SWCNT), which consist of a two-dimensional hexagonal lattice of carbon atoms, possess unique mechanical, electrical, optical and thermal properties. SWCNT can be synthesized in diverse chiral indexes to determine certain attributes. This work theoretically investigates electron transport in different directions along SWCNT. The electron studied in this research transfers from the quantum dot that can possibly move to the right or left direction in SWCNT with different valley-dependent probability. These results show that valley polarized current is present. The valley current in the right and left directions has a composition of valley degrees of freedom where its components (K and K') are not identical. Such a result can be traced theoretically by certain effects. That firstly is the curvature effect on SWCNT in which the hopping integral between [Formula: see text] electrons from the flat graphene is altered, and another is curvature-inducing [Formula: see text] mixture. Due to these effects, the band structure of SWCNT is asymmetric in certain chiral indexes leading to the asymmetry of valley electron transport. Our results exhibit that the zigzag chiral indexes is the only type making electron transport symmetrical that is different to the result from the other chiral index types which are the armchair and chiral. This work also illustrates the characteristic of the electron wave function propagating from the initial point to the tip of the tube over time, and the current density of the probability in specific times. Additionally, our research simulates the result from the dipole interaction between the electron in QD and the tube that impacts the lifetime of the electron being in QD. The simulation portrays that more dipole interaction encourages the electron transfer to the tube, thereby shortening the lifetime. We as well suggest the reversed electron transfer from the tube to QD that the time duration of such transfer is much less than the opposite transfer owing to the different orbital of the electron's states. Valley polarized current in SWCNTs may also be used in the development of energy storage devices such as batteries and supercapacitors. The performance and effectiveness of nanoscale devices, including transistors, solar cells, artificial antennas, quantum computers, and nano electronic circuits, must be improved in order to achieve a variety of benefits.
RESUMEN
Quantum dot (QD) gas sensors are one of the most useful nanotechnologies applied to protect people from unnecessary harm. This work theoretically explores the mechanism in QD gas sensors in order to advance the prudent design of relevant products. The theoretical model employed in this research is similar to the process in plants' photosynthesis, referred to as charge separation of light harvesting. In this work, we investigate the details of energy transport in QD gas sensors carried by electrons from the circuit. We demonstrate theoretically how the effects of temperature and gas detection affect electron transport. To analyze thoroughly, the potential energy referred to as the Schotthy barrier perturbed by gasses is considered. Moreover, the energy transfer efficiency (ETE) of QD gas sensors for oxidizing or reducing gas is shown in the simulation. The results imply that the electron transport between QDs (raising the current and lessening the current) depends on a parameter corresponding with the Schotthy barrier. In regard to thermal energy portrayed by phonon baths, a higher temperature shortens the time duration of energy transport in QDs, hence raising energy transfer efficiency and energy current. Our model can be applied to further QD gas sensors' design and manufacture.
RESUMEN
In our work, we investigate characteristics of conductivity for single-walled carbon nanotubes caused by spin-orbit interaction. In the case study of chirality indexes, we especially research on the three types of single-walled carbon nanotubes which are the zigzag, the chiral, and the armchair. The mathematical analysis employed for our works is the Green-Kubo Method. For the theoretical results of our work, we discover that the chirality of single-walled carbon nanotubes impacts the interaction leading to the spin polarization of conductivity. We acknowledge such asymmetry characteristics by calculating the longitudinal current-current correlation function difference between a positive and negative wave vector in which there is the typical chiral-dependent. We also find out that the temperature and the frequency of electrons affect the function producing the different characteristics of the conductivity. From particular simulations, we obtain that the correlation decrease when the temperature increase for a low frequency of electrons. For high frequency, the correlation is nonmonotonic temperature dependence. The results of the phenomena investigated from our study express different degrees of spin polarization in each chiral of single-walled carbon nanotube and significant effects on temperature-dependent charge transport according to carrier backscattering. By chiral-induced spin selectivity that produces different spin polarization, our work could be applied for intriguing optimization charge transport.
RESUMEN
We illustrate Kerr and Faraday rotation in the strained-graphene by applying the second quantization method as an alternative approach. We consider the right- and left-going photon fields coupling with strained graphene. In other words, we have a new stationary state solution describing this phenomenon. A single-photon polarization in the provided state is considered in cases of a non-magnetic field, and uniform strained graphene. We show that the optical l properties of Faraday rotation, reflectance, and transmittance depend on the spinor phase and the energy level of an electron in strained graphene. These values can be controlled by variation of a strain parameter and strain types. Then, it is possible to have an alternative measurement of the pseudo-spin state and electronic structure in the 2-D layer by observing the optical properties of the single-photon in the provided state.
RESUMEN
We investigate that effect of the curvature on induced hybridization and modification of emission profiles for each chiral's index single-wall carbon nanotubes (SWCNTs). According to the Schwinger two particle pair state method, we provide an analytical expression by calculating polar of spot intensity as a function of the polar angle. The emission profiles for indirect transition have an asymmetric shape as a function of the electron wave vector of the axis direction kt and depend on the chiral index. Here we show polarization-dependent, given analytically by expanding the matrix element into the scalar product of the light polarization vector and the dipole vector. These scalar products having a maximum value depend on the summation of phase factors of spinors of electrons in the conduction band Φc and valence band Φv. In the case of direct transition, dipole vector tube axis is maximum at the phase summation of Φc and Φv is 0 or 2π. In contrast, the maximum dipole vector circumference is obtained at the phase summation of π for the case of indirect transition. We can predict a strong emission peak and emission profiles which can be used to identify optical transitions in an individual SWCNT with different chiral indices experimentally.