Graphene Nanostrips Research Articles

Dataset for Electronics and Plasmonics in Graphene, Silicene, and Germanene Nanostrips

Dataset for Electronics and Plasmonics in Graphene, Silicene, and Germanene Nanostrips

Influence of graphene nano-strips on the vibration of thermoelastic nanobeams

This research deals with the investigation of the vibrational behavior of thermoelastic homogeneous isotropic nanobeams, with particular emphasis on the application of non-Fourier heat conduction theory. The nanobeam is configured with one end having a graphene nano-strip connected to an electrical source supplying a low voltage current. To analyze this system, the Green-Naghdi type I and type III theorems are applied within the framework of simply supported boundary conditions while maintaining a fixed aspect ratio. The nanobeam is subjected to thermal loading due to the heat generated by the current flow through the graphene nano-strip. The governing equations are solved in the Laplace transform domain, and the inverse Laplace transform is computed numerically using Tzou's approximation method. Our results, as shown in the figures, reveal different scenarios characterized by varying electric voltage and electric resistance values for the nanographene strips. It is evident that these parameters exert a profound influence on the functional behavior of the nanobeam, thus providing a mechanism to regulate both its vibrational characteristics and temperature rise through judicious manipulation of the electrical voltage and resistance levels.

Modeling Plasmonics and Electronics in Semiconducting Graphene Nanostrips

In recent decades, both academia and industry have shown noteworthy interest in investigating the semiconducting properties of graphene. Nevertheless, the lack of a suitable bandgap in graphene has restricted its practical applications in the current semiconductor industry. To overcome this limitation, graphene micro/nano-strips have been actively explored. The focus of the present study centers on modeling the electronic and plasmonic characteristics of graphene strips with varying widths: 2.7, 100, 135 nm, and 4 m. This analysis is conducted at ultralow energies (0.3 eV, or ~73 THz). We employ conventional density functional computations to estimate the Fermi velocity of graphene, refining the results via the GW approximation. Utilizing the accurate Fermi velocity, we employ a semi-analytical model to explore the ground state and plasmon properties (frequency and dispersion) of these graphene strips. Notably, this approach effectively replicates the density of states observed in narrow experimental graphene nano-strips (2.7 nm) grown on Ge(001) and, similarly, reproduces the plasmon spectrum found in synthesized graphene microstrips (4 μm) on Si/SiO2. Interestingly, our study also offers insights into the potential application of this approach in comprehending the plasmon frequency and plasmon dispersion of graphene nano-strips (~135 nm) acquired through liquid-phase exfoliation. The outcomes of this investigation present compelling evidence that the properties of graphene-based strips can be customized to fulfill specific requirements and applications. These findings hold significant promise for advancing graphene-based technologies, bridging the gap between fundamental research and tangible applications. Doi: 10.28991/ESJ-2023-07-05-01 Full Text: PDF

Thermo-electrical influence of graphene nano-strip on viscothermoelastic nanobeam vibration based on Lord–Shulman model

Thermoelastic, homogeneous, and isotropic nanobeams have a significant analysis in this study that has been established within the context of the Lord–Shulman heat conduction equation. A graphene strip at the first end of the nanobeam acts as the basis for an application that includes an electrical current with a low voltage. The thermal effect of the electrical current has thermally loaded the nanobeam under constant side ratios and simply supported boundary conditions. The Laplace transform method was used to resolve the governing differential equations for the time variable. In the domain of the Laplace transform, the solutions were calculated. The numerical computation of the Laplace transform inversions was performed using Hoing’s approximation approach based on an iteration formula. Graphs illustrating various situations were used to demonstrate the numerical results for various electrical voltage and resistivity values for the graphene nano-strip. Nanobeam functions were found to be significantly influenced by electrical voltage and electrical resistance. Therefore, by varying the voltage and resistance applied to the nanobeam, vibration and temperature increments could be controlled.

Organic-catalysis-free and low-temperature synthesis of vertically aligned graphene nano-stripes for enhancing performance of LiFePO4-based Li-ion batteries

Practical and efficient integrations of graphene into real applications are identically important as their various superior properties. Among various graphene-related materials, vertical graphene stripes (VGSs, in nanoscale) are one kind of interconnected graphene sheet oriented perpendicularly to the growth substrate with 3-dimensional porous structures. Due to the high surface-to-volume ratio, VGSs could be an even better candidate than pure graphene when considering the physical mixing of graphene-related materials with other substances. In this study, we demonstrate an organic-catalysis-free and low-temperature approach (<300 °C) to efficiently grow VGSs without utilizing any environmentally harmful chemicals. The as-synthesized VGSs were comprehensively characterized by means of different microscopes, Raman spectra, X-ray diffractometers, and electrochemical tests. Compare with existing literature, a discrepancy in terms of growth mechanism was first discovered via time-independent Raman spectra, showing that the horizontal buffer layers are not necessary prior to the formation of VGSs. More importantly, the as-synthesized VGSs were introduced into the cathode of Li-ion batteries, and outstanding functionalities such as specific capacity and charge/discharge stabilities were found to even outperform carbon black (C65), the classic commercial conductive additive.

Dynamical controllable optical device designed by tunable graphene nanostructures in a PIT structure

Plasmonically induced transparency (PIT) is the classical counterpart of the Electromagnetically induced transparency (EIT) as a quantum nonlinear phenomenon that is achievable in metamaterial structures. In recent years, considerable research has been dedicated to metamaterials for the realization of PIT. Graphene metamaterials have drawn significant attention as a research area due to their unique characteristics, such as surface conductivity tunability by gate electrical biasing. Unlike the EIT effect, the PIT phenomenon is usually achieved between two resonators via near-field coupling without applying any pump. The distance between the two resonators is a vital parameter in PIT. The variation in the coupling strength requires physical parameter reformation of the PIT structure or material change. Here, two bright and dark resonators are utilized. By engineering the electrical field pattern of the bright resonance mode, the coupling strength dynamically changes. For this purpose, three graphene nanostrips as an adjustable quantum structure are used to form a bright resonator, and the quantum confinement of the carriers controls the coupling strength. In addition, the PIT quality factor is engineered from 33.87 for the quantum barrier case to 69.9 for the quantum-well case. Therefore, the coupling strength between the bright and dark resonators can be managed without any geometrical or material changes.

Thermo-electrical influence of graphene nano-strip on viscothermoelastic nanobeam vibration

In this article, Green-Naghdi type-II heat conduction law was used, and a new analysis of viscothermoelastic, homogeneous, and isotropic nanobeams has been developed. The first end of the beam is based on a graphene nanostrip connected to electricity with a low-voltage current. A thermal load has been applied to the nanobeam due to an electrical current causing a thermal effect. Under simply supported boundary conditions with a fixed aspect ratio, the Green-Naghdi theorem of Type-II has been applied. The Laplace transform domain has been used to calculate the solutions of governing equations. Hoing's approximation approach has been used to calculate the inverse Laplace transformation numerically. In this study, different values of electrical voltage and electrical resistance were used for different cases. Nanobeam functions were found to be significantly influenced by electrical voltage and electrical resistance. Thus, vibration and temperature increment could be controlled by varying electrical voltage and electrical resistance applied to the nanobeam.

Chiral Optical Properties of Möbius Graphene Nanostrips.

The advancement of optical technology demands the development of chiral nanostructures with a strong dissymmetry of optical response. Here, we comprehensively analyze the chiral optical properties of circular twisted graphene nanostrips, with a particular emphasis on the case of a Möbius graphene nanostrip. We use the method of coordinate transformation to analytically model the electronic structure and optical spectra of the nanostrips, while employing the cyclic boundary conditions to account for their topology. It is found that the dissymmetry factors of twisted graphene nanostrips can reach 0.01, exceeding the typical dissymmetry factors of small chiral molecules by 1-2 orders of magnitude. The results of this work thus demonstrate that twisted graphene nanostrips of Möbius and similar geometries are highly promising nanostructures for chiral optical applications.

Nanoscale flow-induced nonlinear vibration of multilayer graphene based-resonators: Slip and transition flow regimes

This paper presents a nanoscale fluid-structure interaction (FSI) model for flow-induced nonlinear vibration of multilayer graphene based-resonators in the slip and transition regimes. Based on the multibeam interlayer shear model with von Kármán geometric nonlinearity and nonlocal modified couple stress theory, the size-dependent equations of motion are obtained for beam resonators laminated of NG-graphene layer and (NG−1) interlayer crosslinks. The small-scale effect on effective viscosity and slip boundary conditions of nanoscale flow is formulated by introducing the average velocity correction factor. For unbounded and bounded (by a rigid wall) nanoflows, the closed-form expressions of velocity correction factor in terms of Knudsen number, as a dimensionless discriminant parameter, are developed to correct the pressure distribution predicted by the potential theory. The present FSI model considers the size effects through the length scale parameter for microstructure local rotation, the nonlocal parameter for long-range interatomic interactions, and Knudsen number for slip condition of nanoscale flow. The Galerkin's method in conjunction with the multiple-scale perturbation technique is used to obtain closed-form solutions of frequency ratio and time-history response. The natural frequencies of cantilever multilayer graphene nanostrips are validated with the ones existing in the literature. Parametric studies are carried out to investigate the influences of small-scale, number of layers, interlayer shear modulus, and fluid characteristics on the linear and nonlinear natural frequencies. Findings show that the critical upstream speed for dynamic instability of the coupled system can change considerably by taking into account the size effects of nanoflow and nanostructures. Therefore, the classical FSI model is inadequate for analyzing nanoscale flow-induced vibration of nanoresonators. Also, it is seen that the effect of geometric nonlinearity becomes very significant for multilayer graphene beams with small interlayer shear modulus.

Single-Electron Transport and Detection of Graphene Quantum Dots

The integrated structure of graphene single-electron transistor and nanostrip electrometer was prepared using the semiconductor fabrication process. Through the electrical performance test of the large sample number, qualified devices were selected from low-yield samples, which exhibited an obvious Coulomb blockade effect. The results show that the device can deplete the electrons in the quantum dot structure at low temperatures, thus, accurately controlling the number of electrons captured by the quantum dot. At the same time, the nanostrip electrometer coupled with the quantum dot can be used to detect the quantum dot signal, that is, the change in the number of electrons in the quantum dot, because of its quantized conductivity characteristics.

The vibration of a thermoelastic nanobeam due to thermo-electrical effect of graphene nano-strip under Green-Naghdi type-II model

In this paper, a new analysis of thermoelastic, homogeneous, and isotropic nanobeams has been constructed in the context of the Green-Naghdi type-II heat conduction law. The first end of the nanobeam is based on a graphene strip, which contains an electrical current with a small voltage which is a novel application. Under simply supported boundary conditions with fixed side ratios, the nanobeam has been thermally loaded with a heat source due to the thermal effect of the electrical current. On the time variable, the Laplace transform technique was utilized to solve the governing differential equations. The solutions were computed in the Laplace transform’s domain. Tzou’s approximation technique based on an iteration formula was used to calculate the Laplace transform inversions numerically. The numerical findings for various values of the electrical voltage and electrical resistivity of the graphene nano-strip have been displayed using graphs illustrating distinct scenarios. All the nanobeam’s researched functionalities have been reported to be influenced by electrical voltage and electrical resistivity. The electrical voltage and resistivity of a graphene nano-strip might be utilized as a tuner to regulate the nanobeam's vibration and energy.

Plasmonic Fano-like resonance in double-stacked graphene nanostrip arrays

We studied the plasmonic response in graphene nanostructures consisting of double-stacked graphene nanostrip arrays with a dielectric spacer on a substrate. The finite-difference time-domain simulations show that the Fano-like resonance in the mid-IR region can be generated due to the plasmonic coupling between the upper- and lower-layer graphene nanostrips. The resonance spectrum can also be effectively controlled by adjusting the geometrical parameters of the graphene system, such as the central position of the graphene nanostrips and the coupling distance between the upper- and lower-layer graphene nanostrips. Moreover, it was found that Fano-like resonance relies on the Fermi level of graphene and polarization angle of incident light, and the spectral response can be well analyzed by using the coupled-mode theory. These results would offer a new pathway to manipulate mid-IR light at the nanoscale and realize ultrasmall graphene functional devices.

Significant Capacitance Enhancement via In Situ Exfoliation of Quasi-One-Dimensional Graphene Nanostripes in Supercapacitor Electrodes

Graphene has received much attention as a supercapacitor electrode material due to its chemical inertness in preventing reaction with electrolytes and the large surface area due to its two-dimensional nature. However, when graphene sheets are processed into electrodes, they tend to stack together and form a turbostratic graphite material with a much reduced surface area relative to the total surface area of individual graphene sheets. Separately, electrochemical exfoliation of graphite is one method of producing single-layer graphene, which is often used to produce graphene for supercapacitor electrodes, although such exfoliated graphene still leads to reduced surface areas due to stacking during electrode fabrication. To utilize the large surface area of graphene, graphene must be exfoliated in situ within a supercapacitor device after the device fabrication. However, graphitic electrodes are typically destroyed upon exfoliation, which is largely due to the loss of electrical connectivity among small exfoliated graphene flakes. Here, we report successful in situ exfoliation of graphene nanostripes, a type of quasi-one-dimensional graphene nanomaterial with large length-to-width aspect ratios, as the anode material in supercapacitors. We find that the in situ exfoliation leads to over 400% enhancement in capacitance as the result of retaining the electrical connectivity among exfoliated quasi-one-dimensional graphene nanostripes in addition to increasing the total surface area, paving ways to fully realizing the benefit of graphene electrodes in supercapacitor applications.

Tunable electromagnetically induced transparency based on graphene metamaterials

In this paper we propose a graphene-based metasurface structure that can exhibit tunable electromagnetically-induced-transparency-like (EIT) spectral response at mid-infrared frequencies. The metasurface structure is composed of two subwavelength mono-layer graphene nano-disks coupled with a mono-layer graphene nano-strip. We show that the coupling of the nano-disks' dipole resonance with the quadrupole resonance of the nano-strip can create two split resonances with a transparency window in between at any desired center frequency within a wide frequency range. We show that such an EIT-like response can also be dynamically shifted in frequency by adjusting the Fermi-level of the graphene through external voltage control, which provides convenient post-fabrication tunability. In addition, the performance of such a metastructure for sensing the refractive index of the surrounding medium is analyzed. The simulation results show that its sensitivity can reach 3016.7 nm/(RIU) with a FOM exceeding 12.0. Lastly, we present an analysis of the slow light characteristics of the proposed device, where the group index can reach as large as 200. Our design provides a new miniaturized sensing platform that can facilitate the development of biochemical molecules testing, etc.

Gold-patched graphene nano-stripes for high-responsivity and ultrafast photodetection from the visible to infrared regime

Graphene is a very attractive material for broadband photodetection in hyperspectral imaging and sensing systems. However, its potential use has been hindered by tradeoffs between the responsivity, bandwidth, and operation speed of existing graphene photodetectors. Here, we present engineered photoconductive nanostructures based on gold-patched graphene nano-stripes, which enable simultaneous broadband and ultrafast photodetection with high responsivity. These nanostructures merge the advantages of broadband optical absorption, ultrafast photocarrier transport, and carrier multiplication within graphene nano-stripes with the ultrafast transport of photocarriers to gold patches before recombination. Through this approach, high-responsivity operation is realized without the use of bandwidth-limiting and speed-limiting quantum dots, defect states, or tunneling barriers. We demonstrate high-responsivity photodetection from the visible to infrared regime (0.6 A/W at 0.8 μm and 11.5 A/W at 20 μm), with operation speeds exceeding 50 GHz. Our results demonstrate improvement of the response times by more than seven orders of magnitude and an increase in bandwidths of one order of magnitude compared to those of higher-responsivity graphene photodetectors based on quantum dots and tunneling barriers.

Plasmonic Fano spectral response from graphene metasurfaces in the MIR region

We present a controlled Fano resonance in the mid-infrared (MIR) region from a kind of plasmonic metasurface consisting of a single-atom-thick surface layer with a periodic pattern of graphene nanostrip pairs on a dielectric substrate. Both the numerical and theoretical results indicate that the Fano resonance spectrum can be flexibly tailored through adjusting the geometrical parameters, such as the asymmetric distance and coupling gap between each pair of graphene nanostrips. Particularly, we achieve the dynamic tunability of the plasmonic Fano resonance spectrum by controlling the polarization of incident light and the Fermi level of graphene. The theoretical calculations agree well with the numerical simulations. These results could find significant applications in nanoscale light control and functional devices operating in the MIR region.

High-yield single-step catalytic growth of graphene nanostripes by plasma enhanced chemical vapor deposition

We report a single-step growth process of graphene nanostripes (GNSPs) by adding certain substituted aromatics (e.g., 1,2-dichlorobenzene) as precursors during the plasma enhanced chemical vapor deposition (PECVD). Without any active heating and by using low plasma power (≤60 W), we are able to grow GNSPs vertically with high yields up to (13 ± 4) g/m2 in 20 min. These GNSPs exhibit high aspect ratios (from 10:1 to >∼130:1) and typical widths from tens to hundreds of nanometers on various transition-metal substrates. The morphology, electronic properties and yields of the GNSPs can be controlled by the growth parameters (e.g., the species of seeding molecules, compositions and flow rates of the gases introduced into the plasma, plasma power, and the growth time). Studies of the Raman spectra, scanning electron microscopy images, ultraviolet photoelectron spectroscopy, transmission electron microscopy images, energy-dispersive x-ray spectroscopy and electrical conductivity of these GNSPs as functions of the growth parameters confirm high-quality GNSPs with electrical mobility ∼104 cm2/V-s. These results together with residual gas analyzer spectra and optical emission spectroscopy taken during PECVD growth suggest the important roles of both substituted aromatics and hydrogen plasma in the rapid vertical growth of GNSPs with large aspect ratios.

Tunable plasmon-induced transparency based on graphene nanoring coupling with graphene nanostrips

We numerically and theoretically demonstrate a plasmon-induced transparency (PIT) at the mid-infrared region with finite-difference time-domain method. The system consists of an optically bright dipole mode and a dark quadrupole mode, which are supported by the graphene nanoring and graphene nanostrips, respectively. The coupling between the two modes introduces transparency window and large group delays. The pronounced PIT resonance can be easily modified by adjusting the geometric parameters and the Fermi level of graphene nanostructure. Our results suggest that the demonstrated PIT effect may be applicated in the slow-light device, active plasmonic switching, and optical sensing.

Dynamically-Tunable Terahertz Band-Stop Filter Based on Multilayer Graphene Metamaterial

In this paper, a dynamically-tunable band-stop filter based on periodically patterned graphene nanostrip and nanodisk in THz wavelength is proposed and numerically investigated at room temperature. The properties of proposed structure are calculated by using the finite-difference time-domain method. The patterned graphenes are excited by the incident light which leads to absorb two different ranges of spectral wavelength. The simulated results show that a wide free spectral range can be achieved by using multilayer graphene. More importantly, it is found that the transmission dips can be dynamically controlled by adjusting the gate voltage. Moreover, the transmission dips change with graphene mobility which corresponds to graphene intrinsic loss. Finally, the proposed metamaterial structure may be used for many applications such as tunable sensors, active plasmonic switches, and slow light devices.

Analysis the effect of the third clutch immediate neighborhood (3NN) and inequality of bond length on the performance of edge of a tunnel field-effect transistors based on graphene Nano Strip

Analysis the effect of the third clutch immediate neighborhood (3NN) and inequality of bond length on the performance of edge of a tunnel field-effect transistors based on graphene Nano Strip