Channel Radius Research Articles

Similarity principle based multi-physical parameter unification and comparison in salinity-gradient osmotic energy conversion

Nanofluidic osmotic energy conversion has the potential of directly converting renewable salinity-gradient energy into electricity. Existing research mainly focuses on the ion selectivity and robustness of nanoporous membranes. However, the multi-physical governing parameters of salinity-gradient osmotic energy conversion have never been unified and compared. In the current study, a similarity principle is constructed for ion selective transport in nanofluidic channel through dimensionless analysis, which lays a theoretical foundation for experimental design and data analysis to develop engineering correlations in osmotic energy conversion under a salinity-gradient. The derived dimensionless governing parameters are grouped into four categories with different physical meanings including ion driving source, ion selectivity, ion transport characteristics, and nanoporous membrane configuration. Particularly, a key dimensionless governing parameter named “IonS” is developed for ion selectivity of nanofluidic channel, indicating that the ion selectivity has a positive linear correlation with the nanochannel surface charge density and a negative linear correlation with ion concentration and nanofluidic channel radius. Considering the similarity phenomena in salinity-gradient osmotic energy conversion, future experimental burden is dramatically alleviated. In addition, a sensitivity analysis using Taguchi method is carried out to evaluate the dominance order of multi-physical parameters in salinity-gradient osmotic energy conversion. The ion concentration and nanofluidic channel radius are found to be dominant for maximum output power and energy conversion efficiency because of their significant influences on the thickness of electric double layer and its overlapping degree. The current dimensionless analysis based similarity principle and sensitivity analysis of multi-physical parameters offer an intrinsic insight for ion selective transport in nanofluidic channels, contributing to the development of salinity-gradient osmotic energy conversion for practical applications.

The propagation dynamics and stability of an intense laser beam in a radial power-law plasma channel

By containing ponderomotive self-channeling, the propagation behavior of an intense laser beam and the physical conditions are obtained theoretically in a radial power-law plasma channel. It is found that ponderomotive self-channeling results in the emergence of a solitary wave and catastrophic focusing, which apparently decreases the region for stable propagation in a parameter space of laser power and the ratio of the initial laser spot radius to the channel radius (RLC). Direct numerical simulation confirms the theory of constant propagation, periodic defocusing and focusing oscillations in the parameter space, and reveals a radial instability which prevents the formation of bright and dark solitary waves. The corresponding unstable critical curve is added in the parameter space numerically and the induced unstable region above the unstable critical curve covers that of catastrophic focusing, which shrinks the stable region for laser beams. For the expected constant propagation, the results reveal the need for a low RLC. Further study illustrates that the channel power-law exponent has an obvious effect on the final stable region and laser propagation, for example increasing this exponent can enlarge the stable region significantly, which is beneficial for guiding of the laser and increases the lowest RLC for constant propagation. Our results also show that the initial laser amplitude has an apparent influence on the propagation behavior.

Design of Swollen Lipidic Cubic Phase to Increase Transcutaneous Penetration of Biomacromolecules.

Lipidic cubic phase (LCP) is a self-assembled system composed of lipids with interpenetrated aqueous channels, and its potential in drug delivery systems has been investigated. Although LCP was shown to improve transcutaneous penetration of hydrophilic molecules of up to 1203 Da so far, the transcutaneous delivery of larger molecules such as proteins has not been achieved. This is likely because proteins are usually larger than the aqueous channels of LCP (∼37.2 Å in diameter), which limits the molecular diffusion in LCP. In this report, we overcome this issue by adding N-octyl-β-d-glucopyranoside to glyceryl monooleate-water-based LCP to give swollen LCP (SLCP), which has larger aqueous channel diameters (∼65.6 Å). First, we systemically evaluated the effect of swelling on drug diffusion in LCP/SLCP. The release kinetics of various peptides and proteins whose sizes ranged from 9.14 to 55.28 Å in diameter were evaluated, and the diffusion coefficients (D) were calculated by the Fickian diffusion model. As expected, all peptides and proteins diffused faster in SLCP than in LCP. A more detailed analysis revealed a negative linear relationship between log D and the ratio of the radius of gyration of the proteins to the aqueous channel radius, indicating that swelling of a cubic nanostructure is an effective strategy to enhance D. Next, the skin penetration of proteins encapsulated in LCP and SLCP was evaluated. The skin penetration of ovalbumin (42.9 kDa), for example, was enhanced by SLCP but not by LCP, and a positive correlation between D and the amount of skin penetration was found. Collectively, this study provides an effective measure for designing LCP systems that enhance transcutaneous penetration of biomacromolecules.

(Invited) Optimization of Highly Ordered Laser-Patterned Electrode (HOLE) Design for Achieving Enhanced Fast Charging Performance in Graphite Anodes with > 3mAh/cm2 loading

For widespread adoption of electric vehicles, we need Li-ion batteries (LIBs) that are both energy and power dense. In the state-of-art Li-ion batteries, there exists a tradeoff between the energy and power density. This tradeoff originates due to the electrode design used in conventional LIBs, where one needs to increase the loading of active material (either in terms of active material mass fraction or the electrode thickness) to achieve high energy density. However, such a design limits the mass transport of electrolyte, which leads to it poor performance at high-charging rates. It has been demonstrated that the rate performance of the energy dense electrodes can be improved by employing 3D architectures such as highly ordered laser-patterned electrode (HOLE),1 which alleviate the electrolyte mass transport limitations by providing rapid mass transport via laser ablated channels through the electrode thickness. In this study, we investigate how the geometric parameters of the HOLE design such as inter-channel spacing and channel radius affect the fast-charging performance of graphite anodes with > 3 mAh/cm2 loading and the HOLE architecture. We conduct this analysis using a fully parameterized continuum scale model based on the porous electrode theory. Our results show that for a constant volume retained (after the laser ablation), the smaller and closer channels exhibit better 4C charging performance than the channels that are larger and farther. The improved performance of a HOLE anode with smaller and closer channels is a result of the small value of the Damköhler number, Da, defined as the ratio between the characteristic diffusion time and reaction time, for the anode. Furthermore, we developed a semi-analytical framework to estimate Da for a given HOLE design, which includes the channel spacing, size, and arrangement. The results from the analysis match closely with the results from the 3D simulations. Thus, our framework can be used for optimization architectures similar to the HOLE architectures without the need of running computationally expensive 3D simulations. In addition to our simulation results, we will also discuss the automated process that was developed to parameterize our model.

Multi-objective constructal design for compound heat dissipation channels in a three-dimensional trapezoidal heat generation body

A three-dimensional compound heat dissipation channel model with both heat conduction and fluid channels in a trapezoidal heat generation body is established in this paper. Firstly, constructal design of the model is conducted by taking the composite function of maximum temperature difference and pumping power consumption as the optimization objective based on the weighted sum method. The optimization results with compound heat dissipation channel and pure fluid channel are compared. Secondly, the Pareto optimal set also obtained by the multi-objective optimization to satisfy different design requirements based on the NSGA-II algorithm. The results show that there exist the optimal fluid channel radius, ratio of trapezoidal height to total length and length ratio of elemental channels to make the composite function of the trapezoidal heat generation body approach its minimum. Compared with the initial design, the composite function is reduced by 25.7% after constructal optimization with three design variables. The result obtained by the weighted sum method is also located at the Pareto optimal set, which simultaneously verifies the results obtained by the weighted sum method and multi-objective optimization method. The optimization results may provide a new theoretical guideline for the designs of various electronic devices.

Evaluation of Morphodynamic Controls on the Preservation of Fluvial Meander‐Belt Deposits

AbstractThe way river morphodynamics influence the preservation of point‐bar deposits at multiple scales is not fully understood. Employing time‐lapse trajectories of natural rivers, a numerical model is used here to simulate planform evolutions of meander‐belt reaches that embody different transformation behaviors and cutoff processes. Proxies for temporal durations are obtained considering the surface area over which a river migrated and channel migration rates that relate to average channel radius of curvature through constant, monotonic, and non‐monotonic relationships. The preservation of meander‐belt deposits over different timescales is assessed at three architectural hierarchies: (a) pairs and (b) sets of accretion packages, and (c) meander‐belts. Results confirm that sediment preservation decreases in a predictable way with the accumulation time; however, accretion rates decay with time in a way that does not follow the expected power‐law. This is interpreted to reflect the effect of the onset of geomorphic thresholds of channel transformation and cutoff.

Analysis of discharge channel characteristics based on three-phase flow dielectric characteristics in USV-MF assisted WEDM-LS

In this paper, considering the effects of the characteristics of the three-phase flow dielectric in the discharge gap flow field on the discharge channels in the ultrasonic vibration and magnetic field assisted low speed WEDM (USV-MF assisted WEDM-LS), the model of discharge channel including discharge position and size of discharge channel is established. Firstly, a mechanism of bubble-particle bridging breakdown was proposed under working condition of cutting workpieces with large thickness. Then a prediction model of the discharge point position in USV-MF assisted WEDM-LS under three-phase flow dielectric characteristics based on the breakdown mechanism was performed, and FEM software COMSOL was used to simulate and analyze this model. By comparing with the experimental results of discharge point position captured by high-speed camera, the accuracy of the prediction results of discharge point position in USV-MF assisted WEDM-LS was verified, it showed that the model can explain the dielectric breakdown more accurately. Next, the model of radius of discharge channel including magnetic field intensity, electric field intensity, medium pressure, and surface tension of discharge channel was established, and the influence of USV and MF on the size of discharge channel was analyzed theoretically. The radius of discharge channel in USV-MF assisted WEDM-LS was obtained by solving the partial differential equation in MATLAB. According to discharge point position and radius of the plasma discharge channel, surface morphology of workpiece was simulated by COMSOL. Finally, the experiment of photographing the discharge channel in USV-MF assisted WEDM-LS was carried out to verify the above model. It showed that the trend of the simulated results of discharge channel position is the same as that of the experimental results, and the error of peak height value between simulated and experimental results is within 6%.

Study of flow effects on temperature-controlled radiofrequency ablation using phantom experiments and forward simulations.

Blood flow is known to add variability to hepatic radiofrequency ablation (RFA) treatment outcomes. However, few studies exist on its impact on temperature-controlled RFA. Hence, we investigate large-scale blood flow effects on temperature-controlled RFA in flow channel experiments and numerical simulations. Ablation zones were induced in tissue-mimicking, thermochromic phantoms with a single flow channel, using an RF generator with temperature-controlled power delivery and a monopolar needle electrode. Channels were generated by molding the phantom around a removable rod. Channel radius and saline flow rate were varied to study the impact of flow on (i) the ablated cross-sectional area, (ii) the delivered generator power, and (iii) the occurrence of directional effects on the thermal lesion. Finite volume simulations reproducing the experimental geometry, flow conditions, and generator power input were conducted and compared to the experimental ablation outcomes. Vessels of different channel radii affected the ablation outcome in different ways. For mm, the ablated area decreased with increasing flow rate while the energy input was hardly affected. For mm and mm, the energy input increased toward larger flow rates; for these radii, the ablated area decreased and increased toward larger flow rates, respectively, while still being reduced overall as compared to the reference experiment without flow. Directional effects, that is, local shrinking of the lesion upstream of the needle and an extension thereof downstream, were observed only for the smallest radius. The simulations qualitatively confirmed these observations. As compared to performing the simulations without flow, including flow effects in the simulations reduced the mean absolute error between experimental and simulated ablated areas from 0.23 to 0.12. While the temperature control mechanism did not detect the heat sink effect in the case of the smallest channel radius, it counteracted the heat sink effect in the case of the larger channel radii with an increased energy input; this explains the increase in ablated area toward high flow rates (for mm). The experiments in a simple phantom setup, thus, contribute to a good understanding of the phenomenon and are suitable for model validation.

Optical Kerr effect field measurements and ad hoc engineering model comparisons.

Optical Kerr effects induced by the propagation of high peak-power laser beams through real atmospheres have been a topic of interest to the nonlinear optics community for several decades. This paper proposes a new analytical model for predicting the filamentation/light channel onset distance in real atmospheres based on modulation instability model considerations. The normalized intensity increases exponentially as the beam propagates through the medium. It is hypothesized that this growth can be modeled as a weighted ratio of the Gaussian beam diameter at range to the lateral coherence radius and can be used to set the power ratio for an absorbing, turbulent, nonlinear media to estimate the beam collapse distance. Comparison of onset distance predictions with those found from computer simulation and deduced from field experiments will be presented. In addition, this model will be used with an analytical approach to quantify the expected radius of light channels resulting from self-focusing both with and without the production of a plasma filament. Finally, this paper will describe a set of 1.5-micron, variable focal length USPL field experiments. Comparisons of theoretical radius calculations to measurements from field experiments will be presented.

Numerical analysis of plasma and shock wave characteristics of the discharge in liquid

Based on conservation equation of energy, channel characteristics of the cylindrical geometry of the plasma were described under different conductivity models. The variation of the channel radius, temperature, resistance, current and dissipated energy with time is obtained. The variation of shock wave pressure at a certain distance from the center of the discharge gap is also given. The results are compared with those calculated based on the spherical geometry of the plasma channel. The purpose of this paper is to provide a reference for further study of physical and chemical characteristics and shock wave characteristics of the discharge in liquid. The results show that there is significant difference in the channel pressure and radius when the plasma channel is respectively regarded as a sphere and a cylinder, but there is little difference in other physical properties. When the physical characteristics except the shock wave characteristic are described by using three conductivity models, the change trend is almost the same, while the shock wave characteristic is described more accurately by using the conductivity model σ2. By comparing the changes of electrical parameters and pressure parameters, the applicability of the model can be selected according to the experimental data or specific research problems, which also provides a reference for further study of the physicochemical characteristics and shock wave characteristics of discharge plasma in liquid.

Shadow poles in the alternative parametrization of R -matrix theory

Nuclear data libraries (ENDF, JEFF, JENDL, CENDL, etc.) document our phenomenological knowledge of nuclear cross sections as interpreted by R-matrix theory. The R-matrix scattering model can parameterize the energy dependence of the scattering matrix in different ways. This article establishes new results on three such sets of parameters: the Wigner-Eisenbud, the Brune, and the Siegert-Humblet parameters. We show how the latter two arise from invariance to the arbitrary boundary condition, and how they can trade-off more complex parameters for a simpler energy dependence parameterization: the scattering matrix pole expansion of Humblet and Rosenfeld. We establish that the scattering matrix's invariance to channel radius sets a partial differential equation on the widths of the Kapur-Peierls operator, which enables us to derive an explicit transformation of the Siegert-Humblet radioactive residue widths under a change of channel radius. Considering the continuation of the scattering matrix to complex wavenumbers, several new results are established. We unveil there exist more Brune parameters than previously thought, depending on the way the scattering matrix is continued to complex energies. This points to a broader conundrum in the field: how to analytically continue the scattering matrix while closing sub-threshold channels. We argue that, contrary to the Lane and Thomas legacy of force-closing sub-threshold channels which introduces spurious poles, analytic continuation is the physically correct way of defining the scattering matrix for complex wave numbers. To back this claim we establish thee results: analytic continuation cancels spurious poles, enforces the generalized unitarity conditions of Eden and Taylor, and closes massive particle channels below threshold by both quantum tunneling and from the definition of the cross section as the ratio of probability currents.

Scattering matrix pole expansions for complex wave numbers inR-matrix theory

In this follow-up article to [Shadow poles in the alternative parametrization of R-matrix theory, Ducru (2020)], we establish new results on scattering matrix pole expansions for complex wavenumbers in R-matrix theory. In the past, two branches of theoretical formalisms emerged to describe the scattering matrix in nuclear physics: R-matrix theory, and pole expansions. The two have been quite isolated from one another. Recently, our study of Brune's alternative parametrization of R-matrix theory has shown the need to extend the scattering matrix (and the underlying R-matrix operators) to complex wavenumbers. Two competing ways of doing so have emerged from a historical ambiguity in the definitions of the shift $\boldsymbol{S}$ and penetration $\boldsymbol{P}$ functions: the legacy Lane \& Thomas "force closure" approach, versus analytic continuation (which is the standard in mathematical physics). The R-matrix community has not yet come to a consensus as to which to adopt for evaluations in standard nuclear data libraries, such as ENDF. In this article, we argue in favor of analytic continuation of R-matrix operators. We bridge R-matrix theory with the Humblet-Rosenfeld pole expansions, and unveil new properties of the Siegert-Humblet radioactive poles and widths, including their invariance properties to changes in channel radii $a_c$. We then show that analytic continuation of R-matrix operators preserves important physical and mathematical properties of the scattering matrix -- cancelling spurious poles and guaranteeing generalized unitarity -- while still being able to close channels below thresholds.

Analytical Current–Voltage Modeling and Analysis of the MFIS Gate-All-Around Transistor Featuring Negative-Capacitance

Recently, in accordance with the demand for development of low-power semiconductor devices, a negative capacitance field-effect-transistor (NC-FET) that integrates ferroelectric material into a gate stack and utilizes negative capacitive behavior has been widely investigated. Furthermore, gate-all-around (GAA) architecture to reduce short-channel effect is expected to be applied after Fin-FET technology. In this work, we proposed a compact model describing current–voltage (I–V) relationships of an NC GAA-FET with interface trap effects for the first time, which is a simplified model by taking proper approximation in each operating region. This is a surface potential-based compact model, which is suitable for evaluating the I–V characteristics for each operating region. It was validated that the proposed model shows good agreement with the results of implicit numerical calculations. In addition, by using the proposed model, we explored the electrical properties of the NC GAA-FET by varying the basic design parameters such as ferroelectric thickness (tfe), intermediate insulator thickness (tox), silicon channel radius (R), and interface trap densities (Net).

Molecular dynamics simulations reveal statistics and microscopic mechanisms of water permeation in membrane-embedded artificial water channel nanoconstructs.

Understanding water transport mechanisms at the nanoscale level remains a challenge for theoretical chemical physics. Major advances in chemical synthesis have allowed us to discover new artificial water channels, rivaling with or even surpassing water conductance and selectivity of natural protein channels. In order to interpret experimental features and understand microscopic determinants for performance improvements, numerical approaches based on all-atom molecular dynamics simulations and enhanced sampling methods have been proposed. In this study, we quantify the influence of microscopic observables, such as channel radius and hydrogen bond connectivity, and of meso-scale features, such as the size of self-assembly blocks, on the permeation rate of a self-assembled nanocrystal-like artificial water channel. Although the absolute permeation rate extrapolated from these simulations is overestimated by one order of magnitude compared to the experimental measurement, the detailed analysis of several observed conductive patterns in large assemblies opens new pathways to scalable membranes with enhanced water conductance for the future design.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ПЫЛЕВОЗДУШНЫХ ТЕЧЕНИЙ ВБЛИЗИ МЕСТНОГО ВЕНТИЛЯЦИОННОГО ОТСОСА ОТ СВЕРЛИЛЬНОГО ОБОРУДОВАНИЯ

A significant amount of dust is released during the drilling process. It negatively affects the cleanliness and ecology of the surrounding space, as well as human health. The design of a local extraction nozzle is proposed for dedusting the process of drilling concrete with standard drills. A computer model of the dust-air flow in the developed nozzle is created in the software package SolidWorks Flow Simulation. The dynamics of dust particles formed during drilling is numerically studied. The behavior of dust particles of different sizes is considered. It is proposed to use the value of the maximum diameter of dust particles completely captured by the suction channel as a criterion for the efficiency of dust particle capture. Three variants of the drilling plane arrangement are considered: floor, ceiling and vertical wall. The dependences of the maximum diameter of dust particles on the intake air flow rate, the distance of the extraction channel on the side surface of the nozzle to the place of its abutment to the drilling plane, and the radius of the suction channel are determined. The results obtained can be used to design and improve systems for capturing dust pollution generated during drilling. The formulated further directions of research are useful for researchers engaged in identifying the processes of capturing dust particles from mobile technological equipment.

Performance evaluation of junctionless double surrounding gate In0.53Ga0.47As nanotube MOSFET using dual material gate engineering

In this paper, the authors present the studies made on drain current (ID) for 5 nm gate length Dual Material (DM) Double Surrounding Gate (DSG) inversion mode (IM) and junctionless (JL) In0.53Ga0.47As nanotube (NT) MOSFET and Silvaco ATLAS 3D TCAD based simulation results are reported. In these studies, the authors have made use of the Non-Equilibrium Green’s Function (NEGF) approach and the self-consistent solution of Poisson’s equation with Schrodinger’s equation. In the case of inversion mode nanotube MOSFET, the channel region is lightly doped. The effect of Dual Material Gate Engineering for In0.53Ga0.47As Nano Tube channel radius 1.5 nm with gate oxide (Al2O3) thickness (0.8 nm) on ID, has also been studied. Further, a comparison of results has been done between IM DM DSG and JL DM DSG NT MOSFET. In the case of JL MOSFET, doping concentrations are optimized for two approaches (i) to get the same ION current as IM device and (ii) to get the same threshold voltage (VTH) as IM device. This results in 10 and 102 times smaller IOFF in matching ION and VTH optimized devices respectively as compared to IM device. It was found that DM Gate Engineering reduces drain induced barrier lowering (DIBL) in IM and JL devices. JL device is found to have much smaller DIBL ~ 21.10 mV/V, almost an ideal SS ~ 60 mV/dec, and a higher ION/IOFF ratio ~ 2.85 × 108 as compared to the results available for CGAA devices in the literature.

Effect of cavity parameters on the propagation of shock wave generated by underwater pulsed discharge

In order to optimize the shock wave generated by underwater pulsed discharge, the relationship between cavity parameters and shock wave propagation is further studied by three-dimensional numerical simulation. According to the sound pressure field distribution obtained by the simulation, the reflection of the shock wave by the reactor wall can be clearly observed. The reflected pressure wave will reach its maximum value and then gradually attenuate. The study also found that when the deposition energy is constant, when the initial radius of the arc channel increases from 0.1 mm to 2.5 mm, the maximum amplitude of the shock wave will increase from 0.22 × 105 Pa to 1.70 × 105 Pa. When the initial radius of the arc channel is constant, as the deposition energy increases, the time to radiate the shock wave becomes earlier, and the maximum amplitude of the shock wave will increase. This means that a higher pressure can be generated by increasing the input of the deposition energy. When the deposition energy is constant, a higher-pressure level can be obtained by increasing the initial radius of the channel. The excitation frequency also affects the shock wave amplitude. Higher excitation frequency can obtain higher pressure amplitude. These methods will increase the efficiency of underwater pulse discharge treatment of bacteria.

Effect of 3 nm gate length scaling in junctionless double surrounding gate SiNT MOSFET by using triple material gate engineering

In this work, drain current ID for 3 nm gate length of triple material (TM) double surrounding gate (DSG) inversion mode (IM) and junctionless (JL) Si nanotube (SiNT) MOSFET has been studied and simulation results are reported using Silvaco ATLAS 3D TCAD. In this device we consider the Non Equilibrium Green’s Function (NEGF) approach and self-consistent solution of Poisson’s equation with Schrodinger’s equation. The channel region is lightly doped in case of IM SiNT MOSFET. The effect of TM Gate Engineering for SiNT channel radius 1.5 nm and gate oxide (SiO2) thickness of 0.8 nm on ID, has been studied. Also comparison of results has been done between IM TM DSG and JL TM DSG SiNT. For a reasonable comparison between Junctionless and Inversion Mode SiNT, in Junctionless SiNT, doping concentration is optimized for two concerns (i) to get the same threshold voltage (VTH) as IM SiNT and (ii) to get the same ION current as IM SiNT MOSFET. This results in 103 times smaller IOFF in both matching VTH and ION optimized device as compared to IM SiNT MOSFET. It was found that TM Gate Engineering reduces drain induced barrier lowering (DIBL) in JL SiNT. JL SiNT MOSFET has a smaller DIBL ~ 61.02 mV/V, almost an ideal SS ~ 60 mV/dec and higher ION/IOFF ratio ~ 2.63 × 109 as compared to available CGAA literature device results.

Simulation analysis of mixing quality in T-junction micromixer with bend mixing channel

In this paper, an analysis of the mixing quality of micromixers with bend curvature is proposed by Computational fluid dynamics simulation. Species transport phenomena are described by a set of conservation equations that is the Continuity equation, Navier-Stokes equation, and Convection-Diffusion equation. Reynolds number is taken in the range of 30 to 500. Firstly the mixing quality of T-junction straight and T-junction with bend curvature are compared. At a higher Reynolds number, microchannel T junction with bend curvature gives higher mixing quality (approx. Mi=46%). The results show that as the Reynolds number increases, the mixing index value, as well as pressure drop value also increases. Further, the effect of bend’s curvature is studied for better mixing quality. For this goal, three bend curvatures of the different radius of 1 mm, 2 mm, and 3 mm but with equal lengths were simulated. The results show that as the channel radius increases, mixing quality increases.

Performance Evaluation of Inversion Mode and Junctionless Dual-Material Double-Surrounding Gate Si Nanotube MOSFET for 5-nm Gate Length

In this work, drain current ID for 5-nm gate length with dual-material (DM) double-surrounding gate (DSG) inversion mode (IM) and junctionless (JL) silicon nanotube (SiNT) MOSFET have been studied and simulation results are reported using Silvaco ATLAS 3D TCAD. For this work, we used the non-equilibrium Green's function (NEGF) approach and self-consistent solution of Poisson's equation with Schrodinger's equation. The conduction band splitting into multiple sub-bands has been considered and there is no doping in channel in case of IM SiNT MOSFET. The effect of DM gate engineering for SiNT channel radius 1.5 nm with 0.8-nm gate oxide (SiO2) thickness on ID has been studied. A comparison of results has been done between IM DM DSG and JL DM DSG CGAA SiNT. In case of JL, doping concentration is optimized for two concerns: (i) to get the same IOn current as IM device and (ii) to get the same threshold voltage VTh as IM. This has resulted in 102 and 103 times smaller IOff in matching IOn and VTh optimized device, respectively, as compared to IM. It is found that DM gate engineering reduces drain-induced barrier lowering (DIBL) for both IM and JL SiNT MOSFET. In this work, JL have much smaller DIBL ~15 mV/V, almost an ideal SS ~60 mV/dec, and higher IOn/IOff ratio ~2.18·108 as compared to available CGAA literature results. Keywords: inversion mode, junctionless, DM DSG, Si nanotube MOSFET, NEGF, ID, SS, DIBL.