Channel Region Research Articles

Influence of JFET Width on Short-Circuit Robustness of 1200 V SiC Power MOSFETs

This paper investigates and compares the static performance and short-circuit (SC) robustness of 1200 V SiC MOSFETs with varying JFET widths (WJFET = 2.0–5.0 μm). Short-circuit measurements as well as electrical-thermal simulations are used to identify thermal distribution and maximum electrical field, providing valuable insights into the design limits. The devices under test (DUTs) with narrow and wide WJFET exhibit different failure mechanisms under SC stress. After the short-circuit failure, interlayer dielectric (ILD) cracks are observed in DUTs with narrow JFET width (WJFET < 3 μm). In contrast, it is discovered that the burn mark is located in the channel region of the device with a wide JFET width. Moreover, the short-circuit withstand time (SCWT) of DUTs with narrow and wide WJFET exhibits varying trends under high temperature conditions (100 °C). These results can help verify the different failure mechanisms and determine an optimal JFET design to improve the trade-off between the static performance and SC ruggedness of the SiC MOSFETs.

Retracted: Study on Transmission Channel and Pollution Sources Region of O3 in Qingyuan City

Retracted: Study on Transmission Channel and Pollution Sources Region of O₃ in Qingyuan City

Emulation of neuro-mimetic dynamics via GaSb/Si heterojunction V-DGTFET leaky-integrate-fire silicon neuron

A leaky integrate and fire (LIF) neuron property is emulated using vertically developed double gate GaSb/Si tunnel field effect transistor (V-DGTFET). The suggested device can precisely replicate the neuronal dynamics after considering and proper validating the numerical simulations. Silvaco-TCAD tool is exploited for emulation of neuronal attributes and found in good agreement with earlier published research data. The article reports the membrane threshold voltage of 0.47 V which is 3.2x, 2.13x, 2.13x, 1.28x times less as compared to silicon nanowire, MOSFET, phase change device and Bulk FinFET neuron. The energy required for mimicking the neurons is computed as 0.748 aJ which is 1.2 × 109, 4 × 107, 4.68 × 107, 1.34 × 107, 7.59 × 106, 8.42 × 103, 4.30 × 103 3.34 × 105, 2.41 × 105, 1.52 × 106, 26.7,2, 3.88 × 103 times less compared to CMOS, phase change device, SOI CMOS, PCMO RRAM, SiNPN, Bulk FinFET, BTBT based PDSOI MOS, FBFET, LBIMOS, DGJLFET, Si NIPIN, DL-TFET, silicon nano wire respectively. The biasing at second gate is used to induce potential well at channel region to accumulate hole carriers produced due to impact ionization. The threshold current is achieved at 0.20 V drain voltage which is 15x, 14x, 10x, and 1.5x less as compared to FinFET, PD-SOI MOSFET, LBIMOS, and DLTFET respectively. Furthermore, calculated spiking frequency of V-DGTFET LIF neuron is 534 GHz. Thus, remarkable enhancement in frequency of operation and an ultra-low energy per spike makes this neuron device a potential solution for implementing the neuro-mimetic behaviour at large scale.

Two-dimensional analytical model for fully depleted SOI MOSFETs with vertical trapezoid doping including effects of the interface trapped charges

The two-dimensional (2D) potential distribution for vertical trapezoidal doping thin-body fully depleted (FD) silicon-on-insulator (SOI) devices is derived by adopting the evanescent mode analysis method, in which the 2D effects in gate oxide region, channel region and buried oxide region are taken into account. Moreover, the effects of interface trapped charge are considered. Using this potential model, the subthreshold performance of the device including subthreshold current, and subthreshold swing under various conditions have been studied. The result shows that the analytical model is good agreement with the simulated results. Therefore, it provides a feasible way of developing new 2D models for vertical trapezoidal doping thin-body FD SOI devices. Besides offering the physical insight into device physics, the analytical model provides the basic designing guidance for vertical trapezoidal doping thin-body FD SOI devices.

Removing the trace organic compounds using graphene oxide nanocomposite membrane cross-linked by melamine

In this study graphene oxide (GO) based active layer was formed on microfiltration substrate to prepared thin file composite forward osmosis (TFC-FO) membrane with high rejection to pesticides. The ideal GO-based membrane should have high stability, durability, and selectivity. To improve the stability of GO based TFC membrane in aqueous solution the GO nanosheets were cross-linked with melamine monomer. An anchoring carbon-nitrogen covalent bond between the GO nanosheets and melamine molecules is thought to supplement to form the nanocomposite structure. As a result of the configuration of melamine molecules within the channel region, a nanocomposite structure has been formed which provides an optimal condition for resisting the flow of hydrated salt ions but creating a pathway for water molecules to flow. According to the FO tests with different draw solutions against DI water feed, the prepared GOM membranes (GO based active layer crosslinked with melamine) showed best performance with trisodium citrate (TSC) draw solution. In the FO model, a water flux of 18.1 LMH was obtained using TSC, which was 970% higher than the NaCl, while the reverse solute diffusion was reduced by 1100%. The effect of GO thickness on FO performance was also studied, by changing GO solution volume during active layer coating (10, 15 and 20 mL GO solution with concentration of 0.1 mg/mL). Result showed that by increasing the GO thickness the water flux increased from 13.7 LMH in GOM.10 to 18.1 in GOM.15. In addition, the nanocomposite membrane shows high rejection against of both diazinon (99.4%) and atrazine (97.3%). In relation to these results, it can be concluded that GO-based membranes can provide clean water in the FO process as an alternative to polymer-based TFC membranes.

Genetic factors predisposing to arrhythmic events and QTc prolongation during follow-up in long QT patients with unaffected QTc at initial presentation: Swedish experience

Abstract Background Patients carrying genetic variants associated with long QT syndrome (LQTS) who initially present with normal QTc (concealed LQTS) is a large and growing group of patients. Long-term progression of QTc interval and risk factors associated with arrhythmic events in this patient group remain poorly described. Purpose 1) To assess the prevalence of concealed LQTS among patients with genetically verified LQTS; 2) To explore genetic factors associated with QTc prolongation and arrhythmic events in patients with concealed LQTS. Methods Adult LQTS patients (LQT1-3) from three cardiogenetic clinics in Sweden were included in a prospective register. Digital ECGs recorded for any reason both in-hospital and in outpatient settings, were retrieved from ECG archives. Concealed LQTS was defined as QTcB < 460 ms in men or <470 ms in women at initial presentation. The proportion of patients exhibiting QTcB above 480, 490 and 500 ms thresholds at any time during follow-up (FU) was assessed. Ventricular arrhythmias (VA) were defined as torsades de pointes, appropriate ICD shock, aborted cardiac arrest or sudden cardiac death. Cardiac events (CE) were defined as VA or syncope. The risk of CE and VA by the age of 60 years associated with LQTS genotype, KCNH2 pore region mutations and KCNQ1 membrane-spanning mutations was assessed using Kaplan Meier survival curve analysis and Cox regression analysis adjusted for sex, proband status and beta blocker use. Results 1). Out of 211 LQTS patients, 89 (42%) had concealed LQTS (52 (58%) women, 22 (25%) probands, 16 (18%) had CE by the time of diagnosis). Median age at diagnosis was 39 [IQR 22-55] years, age at the end of FU 47 [31-62] years. Concealed LQTS prevalence did not differ between genotypes: LQT1 – 59/141 (42%), LQT2 – 25/57 (44%), LQT3 – 5/13 (39%). 2). LQT1 patients were least and LQT3 patients were most prone to develop QTc prolongation during FU (Table). 3). VA were reported in 3 (3.5%) patients and in all cases preceded by syncope. None of the LQT1 patients experienced VA during FU. Both VA events among LQT2 patients were reported in carriers of KCNH2 pore region mutations (log rank p=0.023). 4). Patients with LQT2 were at higher risk to develop CE than LQT1 patients (HRadj=3.04 95%CI 1.22-7.55). Among LQT1 patients, carriers of mutations affecting membrane-spanning KCNQ1 channel region tended to have higher risk of CE (log rank p=0.018, HRadj=3.99 95%CI 0.80-19.89). Conclusions Concealed LQTS patients represent a significant proportion of the LQTS population and are similarly distributed between the most common LQTS genotypes. These patients have low risk of VA, which is confined to LQT3 patients and LQT2 patients carrying KCNH2 pore region mutations. Concealed LQT1 patients are at the lowest risk of CE and VA and have the lowest risk of experiencing QTc prolongation during FU. Carriers of mutations affecting KCNQ1 membrane-spanning region represent the high-risk LQT1 group with regard to CE.Concealed LQTS patients characteristicsRisk of VA in concealed LQTS by genotype

Impact of Parametric Variation on the Characteristics and Performance of CNTFET Inverter

In this paper, a simple carbon nanotube field effect transistor (CNTFET)-based inverter has been simulated and the impacts of changing various design and process parameters on its characteristics and performance have been analysed using HSPICE. The 32 nm CNTFET model of Stanford University has been used here for the simulation of the inverter. The simulation results and the voltage transfer characteristics (VTC) curve of the inverter have been extracted for (i) different channel lengths, (ii) top gate di-electric material thickness (tox), (iii) pitch value (iv) the number of tubes in CNTFET channel region and (v) chirality of the CNT. It has been observed that the VTC curve changes significantly with different values of these parameters. Some important output parameters like maximum dc current, power, rise time, fall time, average propagation delay, etc. have been measured in each case. Changes in maximum power consumption value due to the change in different parameter values are observed through plotted graphs. Output dc current vs. input voltage graphs have been plotted for different chirality of the tubes, the number of the tubes, and pitch values between n-type CNTFET and p-type CNTFET of the inverter.

Effects of Joule heating and reaction mechanisms on couple stress fluid flow with peristalsis in the presence of a porous material through an inclined channel

Abstract The objective of this study is to assess the flow behavior of the peristalsis mechanism of a couple stress fluid in incorporating a porous material. In addition, reaction mechanism and Ohmic heating are also taken into consideration with slip boundary conditions. For the purposes of mathematical simulation, we assume a long-wavelength approximation, ignoring the wave number and taking a low Reynolds number into account. The obtained outcome is shown in a graphical manner and then analyzed. The results of this investigation reveal that when the Hartmann number improves, the pattern of velocity noticeably decelerates. The Lorentz forces have a retarding impact on the velocity of the fluid from a physical standpoint. As the couple stress variable rises, so does the velocity of the fluid. As the couple stress component increases, the skin friction coefficient increases in one region of the fluid channel and falls in another region, between x = 0.5 and x = 1. As the thermal slip variable rises, more heat is transferred through the surface to the fluid, resulting in a rise in the temperature profile. When the couple stress variable is raised, the Nusselt number rises, while the thermal radiation factor causes the Nusselt number to decline. The results showed a positive relationship between the Sherwood number and the reaction mechanism parameter. This study demonstrates the potential use of this research in the fields of a career in engineering, namely, in enhancing hydraulic systems, as well as in medicine, particularly in optimizing gastrointestinal processes. The process of dissection facilitates the unimpeded circulation of blood and lymph inside the vascular system of the body, enabling the delivery of oxygen to tissues and the elimination of waste materials.

Geometrically designed amorphous oxide semiconductor heterojunction thin-film transistors for enhanced electrical performance and stability

We report the geometrical design of indium-zinc-tin-oxide/zinc-tin-oxide (IZTO/TZO) heterojunction thin-film transistors (TFTs) to achieve high electrical performance and stability. The coverage ratio of the IZTO front-channel-layer (FCL) in the channel region was varied to investigate its impact on electrical properties such as field-effect mobility and bias stability. We observed that with a 90% coverage ratio of IZTO FCL, the mobility increased from 15.9 cm2 Vs−1 to 20.4 cm2 Vs−1, with a suppressed threshold voltage (V th) shift. The IZTO/ZTO TFTs exhibited improved positive gate-bias stability showing a V th shift of +2.46 V. The band bending occurring at the heterointerface is attributed to the enhanced electrical performance.

RIS-Aided Multiuser MIMO-OFDM With Linear Precoding and Iterative Detection: Analysis and Optimization

In this paper, we consider a reconfigurable intelligent surface (RIS) aided uplink multiuser multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) system, where the receiver is assumed to conduct low-complexity iterative detection. We aim to minimize the total transmit power by jointly designing the precoder of the transmitter and the passive beamforming of the RIS. This problem can be tackled from the perspective of information theory. But this information-theoretic approach may involve prohibitively high complexity since the number of rate constraints that specify the capacity region of the uplink multiuser channel is exponential in the number of users. To avoid this difficulty, we formulate the design problem of the iterative receiver under the constraints of a maximal iteration number and target bit error rates of users. To tackle this challenging problem, we propose a groupwise successive interference cancellation (SIC) optimization approach, where the signals of users are decoded and canceled in a group-by-group manner. We present a heuristic user grouping strategy, and resort to the alternating optimization technique to iteratively solve the precoding and passive beamforming sub-problems. Specifically, for the precoding sub-problem, we employ fractional programming to convert it to a convex problem; for the passive beamforming sub-problem, we adopt successive convex approximation to deal with the unit-modulus constraints of the RIS. We show that the proposed groupwise SIC approach has significant advantages in both performance and computational complexity, as compared with the counterpart approaches.

Enhancement of two-phase flow and mass transport by a two-dimensional flow channel with variable cross-sections in proton exchange membrane fuel cells

A novel two-dimensional flow channel (TDFCH) with variable cross-sections geometrically controlled by sinusoidal function is proposed for proton exchange membrane fuel cells (PEMFCs). Two-phase flow simulations and visualisation experiments are combined to reveal the mechanisms for improved water management and enhanced reactant transport. Results show that the centrifugal force generated by the vortex pushes the liquid water away from the central region of the flow channel, forming droplet and film flows to avoid blockage of the flow channel. The reactant gases accumulate on the windward side of the variable-diameter structures, leading to an increase of the local pressure and facilitating fuel diffusion into the porous electrode. The fluid inertia enhances mass transfer of reactants and removal of liquid water inside the porous electrode. The amplitude A of the flow channel based on sinusoidal curve plays a dominant role in improving the performance of the TDFCH. Under the same testing conditions, when amplitude A = 0.2 and period T = 2, the peak power density of the TDFCH-based cell reaches 517.9 mW cm−2, which is 26 % higher than the conventional straight flow channel. The newly designed TDFCH provides an efficient solution to realize performance improvement and long-term stable operation of PEMFCs.

Low working loss Si/4H–SiC heterojunction MOSFET with analysis of the gate-controlled tunneling effect

A silicon (Si)/silicon carbide (4H–SiC) heterojunction double-trench metal-oxide-semiconductor field effect transistor (MOSFET) (HDT-MOS) with the gate-controlled tunneling effect is proposed for the first time based on simulations. In this structure, the channel regions are made of Si to take advantage of its high channel mobility and carrier density. The voltage-withstanding region is made of 4H–SiC so that HDT-MOS has a high breakdown voltage (BV) similar to pure 4H–SiC double-trench MOSFETs (DT-MOSs). The gate-controlled tunneling effect indicates that the gate voltage (VG) has a remarkable influence on the tunneling current of the heterojunction. The accumulation layer formed with positive VG can reduce the width of the Si/SiC heterointerface barrier, similar to the heavily doped region in an Ohmic contact. This narrower barrier is easier for electrons to tunnel through, resulting in a lower heterointerface resistance. Thus, with similar BV (approximately 1770 ​V), the specific on-state resistance (RON-SP) of HDT-MOS is reduced by 0.77 ​mΩ‧cm2 compared with that of DT-MOS. The gate-to-drain charge (QGD) and switching loss of HDT-MOS are 52.14 ​% and 22.59 ​% lower than those of DT-MOS, respectively, due to the lower gate platform voltage (VGP) and the corresponding smaller variation (ΔVGP). The figure of merit (QGD ​× ​RON-SP) of HDT-MOS decreases by 61.25 ​%. Moreover, the heterointerface charges can reduce RON-SP of HDT-MOS due to trap-assisted tunneling while the heterointerface traps show the opposite effect. Therefore, the HDT-MOS structure can significantly reduce the working loss of SiC MOSFET, leading to a lower temperature rise when the devices are applied in the system.

The London, Paris and De Bilt sub‐daily pressure series

AbstractThe construction of sub‐daily pressure series is described for the cities of London (GB) and Paris (FR). The series extend back 1692 and 1748, respectively, and as such they represent two of the longest sub‐daily series of barometric pressure available. These series are updated from the previously documented London and Paris daily series and offer more homogeneous series, and in the case of the London series a more temporally complete sequence of data. A pairwise homogenization procedure has been applied to the two series alongside the long series of pressure that exists for De Bilt (NL). The De Bilt series has been available for some time in the International Surface Pressure Dataset (ISPD), but further quality control and homogeneity‐checking procedures have been applied to the data in this paper and therefore the three series are released together in this dataset. The series are of immediate interest for understanding changes to storm activity across the English Channel and North Atlantic region over an extended timeframe but may also be assimilated into reanalysis datasets such as the 20th‐century reanalysis.

Impact of P-type doping and channel length on the performance of 2D SiC MOSFET

The performance of monolayer two-dimensional SiC MOSFET with various concentration of p-type doping in source/drain region and various lengths of channel were investigated based on the density-functional theory method. All MOSFETs could realize dynamic turn-off. The maximum ON-state current were up to 1152.8 μA/μm and 1731.4 μA/μm for 4.1 nm and 5.1 nm SiC MOSFET with 5 × 1020 cm−2 doping concentration, respectively, which could satisfy the requirement of the high-performance devices outlined by ITRS for production year 2028. In addition, the various parameters (transmission spectra, the intrinsic gate capacitance and so on) of MOSFETs were studied. Moreover，the LDOS and spectral current under ON-state voltage were researched to further explore the physical mechanism of the MOSFETs. Furthermore, the study found that the current increased as the temperature increasing, the current value and the temperature difference between left and right electrode at the fixed bias voltage and gate voltage were not related.

Identification over quantum broadcast channels

Identification over quantum broadcast channels is considered. As opposed to the information transmission task, the decoder only identifies whether a message of his choosing was sent or not. This relaxation allows for a double-exponential code size. An achievable identification region is derived for a quantum broadcast channel, and a full characterization for the class of classical-quantum broadcast channels. The identification capacity region of the single-mode pure-loss bosonic broadcast channel is obtained as a consequence. Furthermore, the results are demonstrated for the quantum erasure broadcast channel, where our region is suboptimal, but improves on the best previously known bounds.

Germanium- and Silicon-Nanotransistor Designs by Electrical and Thermal Self-Consistent Analysis

This study evaluated nanometer gate length germanium (Ge) transistors, including the electrical and thermal components, and compared them with silicon (Si) transistors. Nanometer-scale Ge and Si junction-less field-effect transistors (JLFETs) were treated for both NFET and PFET devices under a transient response. Consequently, the electrical and thermal self-consistent simulations revealed that hole carrier transport is more challenging at the channel region for PFET, inhibiting process shrinking. Moreover, the results show that self-heating can reach a dangerous stature, particularly when the channel region is thick. This is because the operation of the nanometer-scale Ge and Si JLFETs depends on the quantum effect, which increases the band-gap energy. The suitable channel design for Ge and Si transistors is almost similar; a heavier doping concentration is favorable for Si transistors. The study concludes that optimizing the channel region to fit the band-gap energy is the most crucial aspect for designing transistors.

Effects of Microstructure on Water Removal in the U-Shaped Region of PEMFC Serpentine Flow Channel

Effects of Microstructure on Water Removal in the U-Shaped Region of PEMFC Serpentine Flow Channel

Evaluation of Anisotropic Biaxial Stress in Extremely-Thin Body (100) Silicon-Germanium-on-Insulator p-Type Metal-Oxide-Semiconductor Field-Effect-Transistor by Oil-Immersion Raman Spectroscopy

We evaluated the anisotropic biaxial strain in the channel region of extremely-thin body silicon-germanium-on-insulator p-MOSFETs by oil-immersion Raman spectroscopy. Oil-immersion Raman spectroscopy can measure the transverse optical (TO) phonon mode which cannot be detected by conventional Raman spectroscopy under the backscattering configuration for (001) substrate. Therefore, we can calculate the anisotropic biaxial stress in the SiGe channel region and investigate the channel width dependence of stress. From the Raman spectra obtained in the polarization configurations of longitudinal optical (LO)-active and TO-active, we confirmed that compressive stress is induced in the SiGe channel region. In addition, we observed that the strain state of the SiGe channel region becomes quasi-uniaxial strain by narrowing the channel width.

Study of Navigable Flow Conditions in the Intermediate Channel of Decentralized Cascade Locks

In this study, the effects of the different conveyance modes of the intermediate channel in decentralized cascade locks on navigation flow conditions were investigated. A new hybrid numerical simulation method was established to evaluate navigable flow conditions in intermediate channels at different water conveyance modes. This hybrid numerical simulation method was reliably compared by physical modeling tests. We used the 33.73 m class high-head intermediate channel filled with water as a study case. The study used the maximum water surface slope and maximum flow velocity as evaluation indexes for navigable flow conditions. The results showed that the navigable flow conditions of the centralized water conveyance mode were worse compared to the decentralized water conveyance mode in the intermediate channel. Especially in the upstream region of the intermediate channel with a centralized outflow, the navigable flow conditions were exceptionally harsh. We recommend the decentralized outflow mode in the high-head intermediate channel. This study provides an effective numerical simulation method for optimizing the water conveyance mode of the high-head intermediate channel of decentralized cascade locks and saving project investment.

Biotemplated precise assembly approach toward ultra-scaled high-performance electronics.

Structural DNA nanotechnology can be programmed into complex designer structures with molecular precision for directing a wide range of inorganic and biological materials. However, the use of DNA-templated approaches for the fabrication and performance requirements of ultra-scaled semiconductor electronics is limited by its assembly disorder and destructive interface composition. In this protocol, using carbon nanotubes (CNTs) as model semiconductors, we provide a stepwise process to build ultra-scaled, high-performance field-effect transistors (FETs) from micron-scale three-dimensional DNA templates. We apply the approach to assemble CNT arrays with uniform pitches scaled between 24.1 and 10.4 nm with yields of more than 95%, which exceeds the resolution limits of conventional lithography. To achieve highly clean CNT interfaces, we detail a rinsing-after-fixing step to remove residual DNA template and salt contaminations present around the contact and the channel regions, without modifying the alignment of the CNT arrays. The DNA-templated CNT FETs display both high on-state current (4-15 μA per CNT) and small subthreshold swing (60-100 mV per decade), which are superior to previous examples of biotemplated electronics and match the performance metrics of high-performance, silicon-based electronics. The scalable assembly of defect-free three-dimensional DNA templates requires 1 week and the CNT arrays can be synthesized within half a day. The interface engineering requires 1-2 d, while the fabrication of high-performance FET and logic gate circuits requires 2-4 d. The structural and performance characterizations of molecular-precise DNA self-assembly and high-performance electronics requires 1-2 d. The protocol is suited for users with expertise in DNA nanotechnology and semiconductor electronics.