Gate Bottom Research Articles

Poly(3-hexylthiophene)-Based Organic Thin-Film Transistors with Virgin Graphene Oxide as an Interfacial Layer.

We fabricated and characterized poly(3-hexylthiophene-2, 5-diyl) (P3HT)-based Organic thin-film transistors (OTFTs) containing an interfacial layer made from virgin Graphene Oxide (GO). Previously chemically modified GO and reduced GO (RGO) were used to modify OTFT interfaces. However, to our knowledge, there are no published reports where virgin GO was employed for this purpose. For the sake of comparison, OTFTs without modification were also manufactured. The structure of the devices was based on the Bottom Gate Bottom Contact (BGBC) OTFT. We show that the presence of the GO monolayer on the surface of the OTFT's SiO2 dielectric and Au electrode surface noticeably improves their performance. Namely, the drain current and the field-effect mobility of OTFTs are considerably increased by modifying the interfaces with the virgin GO deposition. It is suggested that the observed enhancement is connected to a decrease in the contact resistance of GO-covered Au electrodes and the particular structure of the P3HT layer on the dielectric surface. Namely, we found a specific morphology of the organic semiconductor P3HT layer, where larger interconnecting polymer grains are formed on the surface of the GO-modified SiO2. It is proposed that this specific morphology is formed due to the increased mobility of the P3HT segments near the solid boundary, which was confirmed via Differential Scanning Calorimetry measurements.

(Digital Presentation) Characterization and Compression Technology of Real 3D Corner Residue Between Dummy Gate and Formed Fin During an Advanced Inductive Coupled Plasma (ICP) Gate Etch Process in Advanced FinFET

3-Dimesional corner residue between Fin and gate bottom plays a key role in gate profile definition and device performance, while the characterization and compression remain challenging due to shortage of analysis technology and decreasing gate/Fin pitch. In this work, cross-section and planar TEM/STEM are adopted together to measure the real corner size. Gate profile loading along Fin is discussed based on the characterizations and further optimized by tuning processes. Several methods including sidewall passivation and ion bombardment modification has been introduced. An excellent FinFET performance is presented, together with a detailed mechanism.

Holding Force and Vertical Vibration of Emergency Gate in the Closing Process: Physical and Numerical Modelling

A two-dimensional unsteady fluid–structure interaction numerical model was established, based on the physical model test, to investigate the influence of vertical vibration on the holding force of an emergency gate in the closing process. Gate motion was controlled by the user-defined function in Fluent. Attention was paid to the relationship between the vertical vibration, hydrodynamic loads and flow discharge. The experiment results show that holding force has three typical forms in the closing process and it is related to the service gate height. The numerical model can reflect the gate vertical vibration and the gate-closing displacement in the form of steps. Gate vertical vibration in the closing process is a motion-induced vibration caused by gate active falling. Moreover, the transition from full-flow to open-flow behind the emergency gate has a great influence on the gate vertical vibration. With a small gate opening, gate vertical vibration makes the flow discharge fluctuation increase. Furthermore, flow discharge has an influence on the gate body loads, which is mainly concentrated in the upstream plate and gate bottom. Finally, the lift force coefficient at the gate bottom is different from the standard and is mainly controlled by the outflow boundary condition. The simulation result is in good agreement with the experiment and the relative error meets engineering requirements, suggesting that the numerical model can successfully simulate the gate fluid–structure interaction and reproduce the characteristics of physical quantities in the closing process.

An Analysis of Aluminium Oxide and Silicon Dioxide as a Dielectric on Nano Structured Bottom Gate Bottom Contact Organic Thin Film Transistor Based Sensor

A Nano-structuredflexible bottom gate bottom contact (BGBC) organic thin film transistor based pentacenesensor was utilisedto compare between the two frequently used dielectric material i.ealuminiumoxide (Al2O3) and silicon dioxide (SiO2). The organic sensor served as an excellent gas sensor which was visualised through the simulation result in the form of variation between itsmax. and min. drain current and Ion /Ioffratio. The Ion / Ioffratio in the case ofaluminiumoxidewas found to be greater as compared to silicon dioxide whereas the minimum drain current was greater in the case of silicon dioxide and vice versa for the maximum drain current. On comparing the sensitivity of the device, which is the ratio of difference between min. drain current in the presence of any toxic gas and min. drain current in the absence of air to the min. drain current in the absence of air with respect tothe twodifferent electrodes wasfound to be 0.0314 for aluminiumoxide and 0.02964 for silicon dioxide. Hence, aluminiumoxide taking upper hand in sensitivity

Surface Buffer IGBT for High Total Performance

A new structure in trench-gate insulated gate bipolar transistor (IGBT) design is proposed and analyzed not only for power loss reduction but also for long-term stability and suppressing electromagnetic interference (EMI) noise using a device simulation. Although turn-off loss and ON-state voltage drop ${V}_{\text {ce(sat)}}$ are improved by injection enhancement (IE) effect, IE effect causes dynamic avalanche that limits turn-off loss reduction and degrades long-term stability by the charge trap at the trench gate oxide interface. In addition, hole current around the gate induces EMI noise due to the negative gate capacitance. This article shows that the proposed surface buffer (SB) IGBT suppresses dynamic avalanche and negative gate capacitance maintaining low power loss by covering the trench gate bottom and hole evacuation from the pMOS channel.

A statistical Model to simulate the Geometry of the Tunnel Gates Lips

The determination of the down pull force for the tunnel gates requires the estimation of the water pressure coefficient (KB), which is affected by the geometry of the gate lip and the water flow beneath the gate. The prediction of (KB) is depended upon the mean head pressure and the distribution of velocity along the bottom gate surface for each lip geometry. A statistical model is predicted to estimate the bottom water pressure coefficient (KB) of the down pull force for a tunnel gate lip.This model is developed from relevant experimental data obtained from hydraulic model tests conducted in laboratory for nine gate lip geometries with nine gate openings for each gate lip geometry to ensure the correctness of the model results by comparing them these data. The statistical model is verified with (SPSS) software for a good correlation coefficient equal to (0.95). The statistical model is applied to reveal the distribution of the (KB) values on the gate bottom surface along the gate lips with different openings ratios between (0.1-0.9) and is indicated the extensions with round edge of the inclined gates lips. From the distribution of the (KB) values indicate that these values are high and vary smoothly along the gate lip for openings ratio between (0.1-0.5), with complete attachment from the leading edge to the trailing edge of the gate bottom surface. For other gate openings (0.6-0.9), the flow is attached at the leading edge of gate bottom and then decreased toward the trailing edge of gate with smooth variation. While the inclined gate lips with extensions reveal that the values of (KB) are approximately constant and uniform which representing stability of gate along the bottom gate surface for openings ratio between (0.1-0.5), and for other gate openings ratio these values vary smoothly from the leading edge to the trailing edge of the bottom surface of gate. Also, the influence of rounded edge of gate lip with (r/d = 1) on the distribution of pressure head along the bottom surface of gate is investigated, where the values of the (KB) values are dropped and decreased toward the trailing edge of gate.

Tribological Performance of Gate Bottom Pivot Friction Pair QT600-3/40Cr and Its Wear Surface Power Spectral Density Characterization

Tribological Performance of Gate Bottom Pivot Friction Pair QT600-3/40Cr and Its Wear Surface Power Spectral Density Characterization

64‐4: Manufacturing and Encapsulation Process of Bottom Gate Bottom Contact Thin‐Film Transistors with a Printed Oxide Semiconductor

We present bottom gate bottom contact staggered oxide semiconductor TFTs, manufactured by using an ink‐jet printed metal oxide semi‐conductor material from the company Evonik. The printed TFTs with optimized process and adjusted channel geometry present high charge carrier mobility values between 10 and 15 cm2/Vs and on/off current‐ratios of more than 106 . The maximum temperature used is 300 °C, which makes the process compatible with the display manufacturing. To achieve a more stable electric behavior and better threshold voltage homogeneity, mainly in the case of positive gate bias stress, we used a solution processed encapsulation to shield the device from the atmospheric effects. The encapsulated TFTs show a considerable stability improvement and present hence an attractive technology alternative for active matrix processes.

Numerical Modeling of Flow over an Ogee Crested Spillway under Radial Gate: VOF and MMF Model

The present research work shows the simulation of the gated flow over an ogee crested spillway for one of water reservoir. The average velocities and Froude Number analysis at various gate openings gives a better insight of flow behavior. Also, the simulations were carried out by changing the gate bottom shape. The STAR CCM+ CFD tool is used to solve the fluid flow performance. The flow parameters near the bottom of the gate have been studied with two types of fluid flow models i.e. Volume of Fluid (VOF) and Multi-Mixture Fluid Models. The use of Volume of Fluid (VOF) multiphase model together with RNG k-e turbulence for the simulation, gives the excellent agreement between the experimental and numerical data. The spillway performance of the gated flow at various gate openings resembles with the actual flow behavior. The applicability of the CFD model to simulate the gated flow over ogee crested spillway is reviewed. The computational model study showed that CFD can be useful in hydraulics structures for designing of various reservoirs. This numerical model gives significant advantage in practice, in terms of parametric studies

Effects of Gate Lip Orientation on Bottom Pressure Coefficient of Dam Tunnel Gate

Vertical-lift tunnel-type gates are subjected to hydrostatic and hydrodynamics forces created as a result of operation conditions of a wide range of partial openings, discharges and heads. Among these forces is the uplift hydrodynamic force resulting from the effects of flow issuing below the gate bottom. The evaluation of this force requires the determination of bottom pressure coefficient (Kb) which is based mainly upon the measurements of the jet flow velocity across the vena contracta, the pressure head distribution along and across the bottom gate surface and pressure head of flow just downstream the gate shaft. In the present research, a random hydraulic model was created to identify the effect of twelve gate lips orientation on the behavior of flow and consequently on the bottom pressure coefficient. The main conclusion is that the values of bottom pressure coefficient (Kb) are inversely proportional to gate opening ratios (Y/Y0) and range from high values with small gate openings ratios and low values for (Y/Y0 > 30%). The study finds that the bottom pressure coefficient (Kb) and the fluctuations flow pattern below the gate surface are influenced mainly by the gate geometry.

Investigation of the novel 4H[sbnd]SiC trench MOSFET with non-uniform doping floating islands

In this paper, a novel 4HSiC trench metal-oxide-semiconductor field-effect transistor (MOSFET) with non-uniform doping floating islands is proposed, using a Gaussian doping profile in the floating islands. The feature of the non-uniform doping floating island is that the doping concentration of upper part is higher than the lower part. The electric field between the floating island and drift region can be reduced by the decrease in the doping concentration of the lower part. At the same time, the high doping concentration for the upper part of the floating island is utilized, so that gate oxide layer at the sharp corner of the trench gate bottom cannot be broken down in advance. The simulation results indicate that the breakdown voltage of the novel structure can increase by 48%, compared with the structure with the uniform doping (6 × 1017 cm−3) floating island. Furthermore, the switching and gate charge characteristics of the UMOSFETs with uniform and Gaussian doping floating islands have been simulated using two simple switching circuits. The results indicate that changing the doping concentration of the floating islands has no negative effect on the switching characteristics.

Reducing cross-flow vibrations of underflow gates: Experiments and numerical studies

An experimental study is combined with numerical modelling to investigate new ways to reduce cross-flow vibrations of hydraulic gates with underflow. A rectangular gate section placed in a flume was given freedom to vibrate in the vertical direction. Horizontal slots in the gate bottom enabled leakage flow through the gate to enter the area directly under the gate which is known to play a key role in most excitation mechanisms.For submerged discharge conditions with small gate openings the vertical dynamic support force was measured in the reduced velocity range 1.5<Vr<10.5 for a gate with and without ventilation slots. The leakage flow significantly reduced vibrations. This attenuation was most profound in the high stiffness region at 2<Vr<3.5.Two-dimensional numerical simulations were performed with the Finite Element Method to assess local velocities and pressures for both gate types. A moving mesh covering both solid and fluid domain allowed free gate movement and two-way fluid–structure interactions. Modelling assumptions and observed numerical effects are discussed and quantified. The simulated added mass in still water is shown to be close to experimental values. The spring stiffness and mass factor were varied to achieve similar response frequencies at the same dry natural frequencies as in the experiment. Although it was not possible to reproduce the vibrations dominated by impinging leading edge vortices (ILEV) at relatively low Vr, the simulations at high Vr showed strong vibrations with movement-induced excitation (MIE). For the latter case, the simulated response reduction of the ventilated gate agrees with the experimental results. The numerical modelling results suggest that the leakage flow diminishes pressure fluctuations close to the trailing edge associated with entrainment from the wake into the recirculation zone directly under the gate that most likely cause the growing oscillations of the ordinary rectangular gate.

Active Area Width and Topography Effects on Sub 45nm Poly Gate CD

Gate critical dimension (CD) is an important parameter in determining the CMOS device performance. During the process of aggressive feature size shrinking in 45nm node and beyond, aside from the recognized topographical impact on the wafer-to-wafer CD variation, the active area (AA) width has to be taken into consideration for the thorough analysis and the rigid control of within-wafer gate CD variation. Roughly 5%~8% within-wafer CD difference was observed on six gate structures (the same defined gate with different AA widths) right after the gate etch. Both topography wafer and blank wafer (deposited merely with gate oxide plus poly-Si) were utilized to identify the potential key contributors to such within-wafer CD variation. Results demonstrate that the shallow trench isolation (STI) step height, one of notorious topography factors, heavily relies on the local AA width. This leads to the instability of poly-Si film thickness, therefore resulting in the inconsistency of gate bottom profile. Despite, the optical proximity correction (OPC) based on the post-gate etch CD could be utilized to assuage the AA width related CD difference to some extent, the dependence of step height on AA width from the synergetic action of CMP and WET process should be solved for the fundamental solution to such within-wafer gate CD variation.

압축성형을 통한 블로우 성형품용 프리폼 성형기술 연구

Novel compression molding system for preform has been developed in this study. The preforms for injection blow molding and injection stretch blow molding are being manufactured by injection molding. However it contains gate mark that affects the bottom crack in the PET bottle. The compression molded preform does not contain gate mark, thus the appearance quality of bottle has been increased and the residual stress near gate(bottom of the bottle) has been reduced. The thickness distributions, haze, and transmittance are well accepted for the preform. Also, flow characteristics of the resin between a core and cavity could be analyzed through computer simulation.

Simulations of emission characteristics of a multigated single carbon nanotube field emitter

In this study, a two-dimensional, particle-in-cell computer simulation code MAGIC was used to investigate the field emission characteristics from a single closed-capped multiwalled carbon nanotube (MWCNT) in a particular quadruple-gated focusing configuration. Simulations have been done on a single MWCNT assuming it is a cylinder with an ellipsoidal cap of 40nm major radius and 10nm minor radius, 20nm in base diameter, and 0.2 or 0.3μm in height. Other simulation parameters in the base case are 0.1μm thickness for each gate, uniform gate hole radius of 0.45μm, and an anode-cathode distance of 20μm. A particular quadruple-gated focusing configuration has been investigated with individual gate bottom to cathode top distances of 1.1, 1.8, 2.9, and 3.9μm, respectively. For this particular quadruple-gated structure with a cathode voltage of 0V, 85V in voltage of the first gate, 224V in voltage of the second gate, 1320V in voltage of the third gate, 1331V in voltage of the fourth gate, and an anode voltage of 1331V, simulation result showed that a current-weighted beam spot radius on the anode plane can be reduced to 17.4nm for a MWCNT height of 200nm. The emission current, however, varies only slightly from 0.311to0.375pA, as the voltage on the third gate is changed from 200to1500V. The region in the vicinity of the second gate acts to focus the emitted electron beam, while that of the third gate acts to diverge the beam. It was also found that using a higher MWCNT would reduce the applied voltages, but the emitted electrons could not be as well focused as the case with shorter MWCNT. For a MWCNT height of 300nm at about 0.3pA emission current, the weighted beam radius is increased slightly to 28.8nm at the optimum focusing condition. For the MWCNT height of 300nm at a higher emission current about 3nA, the weighted beam radius was found to increase to 46.4nm at the optimum focusing condition. This study shows that it is possible to design a quadruple-gated MWCNT field emitter having few tens of nanometer focused beam size at picoampere to nanoampere emission current range and the designed field emitter is suitable for parallel electron-beam lithography applications.

3717 テンタゲートにおける変動流量係数とその開度依存性(J13-3 流動励起振動3(直交流れによる振動等),J13 流体関連の騒音と振動)

The flow-induced coupled-mode self-excited vibration of huge Tainter gates were theoretically analyzed, and it was confirmed the validity by the model experiments. However, the experimental results have suggested that the instantaneous flow-rate coefficient does not correspond to 1:1 to vibration of a gate. Therefore, in order to clarify the characteristic of the instantaneous discharge flow from the gate bottom, we had many experiments. However, there was a problem on measurement accuracy in response to the influence of the contraction flow. This paper present the test results for variations in flow rate from the gate bottom. The instantaneous discharge velocity caused by the gate vibration was measured at the down-stream rather than the gate bottom, by LDV. The characteristics of instantaneous discharge flow were examined in detail, and the dependability of gate opening was also examined.

Criteria for Dynamic Flow Behavior below the Vibrating Sluice Gates

This paper describes the results of experimental investigation on flow behavior below vibrating sluice gate models considering different gate bottom thicknesses. The pressure and force acting on gate bottom during underflow weremeasured. Based on Eulernumber variation on gate bottom, a criteriahas beendeveloped in termsof upstream head, gate opening ratio and gate bottomthickness for identifying the three cases of flow behaviorbelow the gate as no-reattachment, stable reattachment and unstable reattachment'. Depending uponthe criteria, the pressure and force fluctuation data wereanalyzedin detailandthe analysis revealed that bothstableand unstable reattachmentgenerate self excitation of the gate and consequently increases hydrodynamic loading significantly.

Gate Vibrations due to Unstable Flow Separation

The unsteady load and vibration behavior of vertical‐lift gates was investigated for different gate‐bottom geometries and disharge conditions in an open channel and at a conduit inlet. In all cases, vibrations occurred in specific ranges of a dimensionless velocity parameter whenever the flow fluctuated between complete separation and reattachment at the gate bottom. The excitation mechanism was attributed to the combined effect of shear‐layer instabilities and motion‐induced vortices shed at the leading edge of the gate bottom. Many puzzling features of in‐flow and cross‐flow vibration of gates with flow underneath can thus be clarified. In addition, it is shown that the slope of the mean lift curve acting on the gate bottom provides an effective means of predicting with reasonable accuracy the critical range of gate openings with respect to potential gate vibration. The prediction method is illustrated in a practical case.

Distributions of Hydraulic Forces Acted on the Gate Bottom in Vibration

The distributions of hydraulic pressure acted on the gate bottom in vibration were measured and the damping coefficients of hydrodynamic forces were analysed for three typesof gates. The study involves forced oscillation tests and it is concluded that the flat bottom has two kinds of modes of negative damping caused by vortex in the lower range of reduced volocity (Vr) and by separated stream line in the higher range of Vr. The beveled edge (α=+15°) has the negative damping only in the higher range of Vr and another one (α=-15°) has none. Hydraulic discussions for these results were given.

Flow-induced self-excited in-flowvibrations of gate plates

In-flow, or streamwise, vibrations with a relatively high frequency may occur in gates whenthere is a small flow opening between the lower gate edge and the bottom of the channel. These in-flow vibrations have been investigated in a single oscillator-type model, consisting of a vertical, 20 mm thick, stiff gate plate with flow underneath. The test programme covered gate openings between 5 and 50 mm and the natural frequency of the model gate was varied between 5·4 and 86·3 Hz (in air). Numerous cases of in-flow vibrations were recorded with a lower gate edge of rectangular cross-section. The thickness of this gate edge was 20 mm and 10 mm successively. The vibrations appeared to occur in three distinct vibration domains, each characterized by a definite range of dimensionless reduced velocity numbers. Gate openings between 0·25 and 1·75 times the gate edge thickness appeared to be sensitive to in-flow vibrations. An explanation for the occurrence of in-flow vibrations was established on the basis of pressure and flow-velocity measurements: the flow underneath the gate detaches from the leading edge and forms a free shear layer. Due to the gate movement the free shear layer takes a wavy shape which results in local flow-velocity oscillations and pressure oscillations under the gate. The formed pressure “waves” propagate under the gate bottom and on passing the trailing edge they cause pressure oscillations on a small strip of the downstream face of the gate. The gate is excited by these pressure oscillations. Gate vibration and the generated pressure waves form a closed-loop feedback system, which means self-excitation. Depending on the number of pressure wavelengths, equivalent to the gate edge thickness, the gate vibrations could be classed in one of three vibration domains. It appeared that in-flow vibrations could be prevented by bevelling the upstream face or the downstream face of the gate edge.