Floating body effect in indium-gallium-zinc-oxide (IGZO) thin-film transistor (TFT).

In this paper, the floating body effect (FBE) in indium-gallium-zinc-oxide (IGZO) thin-film transistor (TFT) and the mechanism of device failure caused by that are reported for the first time. If the toggle AC pulses are applied to the gate and drain simultaneously for the switching operation, the drain current of IGZO TFT increases dramatically and cannot show the on/off switching characteristics. This phenomenon was not reported before, and our study reveals that the main cause is the formation of a conductive path between the source and drain: short failure. It is attributed in part to the donor creation at the drain region during the high voltage (Vhigh) condition and in part to the donor creation at the source region during the falling edge and low voltage (Vlow) conditions. Donor creation is attributed to the peroxide formation in the IGZO layer induced by the electrons under the high lateral field. Because the donor creation features positive charges, it lowers the threshold voltage of IGZO TFT. In detail, during the Vhigh condition, the donor creation is generated by accumulated electrons with a high lateral field at the drain region. On the other hand, the floating electrons remaining at the short falling edge (i.e., FBE of the IGZO TFT) are affected by the high lateral field at the source region during the Vlow condition. As a result, the donor creation is generated at the source region. Therefore, the short failure occurs because the donor creations are generated and expanded to channel from the drain and source region as the AC stress accumulates. In summary, the FBE in IGZO TFT is reported, and its effect on the electrical characteristics of IGZO TFT (i.e., the short failure) is rigorously analyzed for the first time.

Development of a chub mackerel with less-aggressive fry stage by genome editing of arginine vasotocin receptor V1a2.

Genome editing is a technology that can remarkably accelerate crop and animal breeding via artificial induction of desired traits with high accuracy. This study aimed to develop a chub mackerel variety with reduced aggression using an experimental system that enables efficient egg collection and genome editing. Sexual maturation and control of spawning season and time were technologically facilitated by controlling the photoperiod and water temperature of the rearing tank. In addition, appropriate low-temperature treatment conditions for delaying cleavage, shape of the glass capillary, and injection site were examined in detail in order to develop an efficient and robust microinjection system for the study. An arginine vasotocin receptor V1a2 (V1a2) knockout (KO) strain of chub mackerel was developed in order to reduce the frequency of cannibalistic behavior at the fry stage. Video data analysis using bioimage informatics quantified the frequency of aggressive behavior, indicating a significant 46% reduction (P = 0.0229) in the frequency of cannibalistic behavior than in wild type. Furthermore, in the V1a2 KO strain, the frequency of collisions with the wall and oxygen consumption also decreased. Overall, the manageable and calm phenotype reported here can potentially contribute to the development of a stable and sustainable marine product.

Recognition of Targets in SAR Images Based on a WVV Feature Using a Subset of Scattering Centers.

This paper proposes a robust method for feature-based matching with potential for application to synthetic aperture radar (SAR) automatic target recognition (ATR). The scarcity of measured SAR data available for training classification algorithms leads to the replacement of such data with synthetic data. As attributed scattering centers (ASCs) extracted from the SAR image reflect the electromagnetic phenomenon of the SAR target, this is effective for classifying targets when purely synthetic SAR images are used as the template. In the classification stage, following preparation of the extracted template ASC dataset, some of the template ASCs were subsampled by the amplitude and the neighbor matching algorithm to focus on the related points of the test ASCs. Then, the subset of ASCs were reconstructed to the world view vector feature set, considering the point similarity and structure similarity simultaneously. Finally, the matching scores between the two sets were calculated using weighted bipartite graph matching and then combined with several weights for overall similarity. Experiments on synthetic and measured paired labeled experiment datasets, which are publicly available, were conducted to verify the effectiveness and robustness of the proposed method. The proposed method can be used in practical SAR ATR systems trained using simulated images.

Demystifying uncertainty in PM10 susceptibility mapping using variable drop-off in extreme-gradient boosting (XGB) and random forest (RF) algorithms.

This study investigates uncertainty in machine learning that can occur when there is significant variance in the prediction importance level of the independent variables, especially when the ROC fails to reflect the unbalanced effect of prediction variables. A variable drop-off loop function, based on the concept of early termination for reduction of model capacity, regularization, and generalization control, was tested. A susceptibility index for airborne particulate matter of less than 10 µm diameter (PM10) was modeled using monthly maximum values and spectral bands and indices from Landsat 8 imagery, and Open Street Maps were used to prepare a range of independent variables. Probability and classification index maps were prepared using extreme-gradient boosting (XGBOOST) and random forest (RF) algorithms. These were assessed against utility criteria such as a confusion matrix of overall accuracy, quantity of variables, processing delay, degree of overfitting, importance distribution, and area under the receiver operating characteristic curve (ROC).

Spatial identification and temporal prediction of air pollution sources using conditional bivariate probability function and time series signature.

Accurate identification of distant, large, and frequent sources of emission in cities is a complex procedure due to the presence of large-sized pollutants and the existence of many land use types. This study aims to simplify and optimize the visualization mechanism of long time-series of air pollution data, particularly for urban areas, which is naturally correlated in time and spatially complicated to analyze. Also, we elaborate different sources of pollution that were hitherto undetectable using ordinary plot models by leveraging recent advances in ensemble statistical approaches. The high performing conditional bivariate probability function (CBPF) and time-series signature were integrated within the R programming environment to facilitate the study's analysis. Hourly air pollution data for the period between 2007 to 2016 is collected using four air quality stations, (ca0016, ca0058, ca0054, and ca0025), situated in highly urbanized locations that are characterized by complex land use and high pollution emitting activities. A conditional bivariate probability function (CBPF) was used to analyze the data, utilizing pollutant concentration values such as Sulfur dioxide (SO2), Nitrogen oxides (NO2), Carbon monoxide (CO) and Particulate Matter (PM10) as a third variable plotted on the radial axis, with wind direction and wind speed variables. Generalized linear model (GLM) and sensitivity analysis are applied to verify and visualize the relationship between Air Pollution Index (API) of PM10 and other significant pollutants of GML outputs based on quantile values. To address potential future challenges, we forecast 3 months PM10 values using a Time Series Signature statistical algorithm with time functions and validated the outcome in the 4 stations. Analysis of results reveals that sources emitting PM10 have similar activities producing other pollutants (SO2, CO, and NO2). Therefore, these pollutants can be detected by cross selection between the pollution sources in the affected city. The directional results of CBPF plot indicate that ca0058 and ca0054 enable easier detection of pollutants' sources in comparison to ca0016 and ca0025 due to being located on the edge of industrial areas. This study's CBPF technique and time series signature analysis' outcomes are promising, successfully elaborating different sources of pollution that were hitherto undetectable using ordinary plot models and thus contribute to existing air quality assessment and enhancement mechanisms.

Production of a tributyltin-binding protein 2 knockout mutant strain of Japanese medaka, Oryzias latipes.

Tributyltin-binding proteins (TBT-bps), members of the lipocalin family, bind TBT in fish blood and are presumed to contribute to detoxification of TBT. Recent studies have shown that many fish species have TBT-bp genes, and that these genes are induced by stresses such as exposure to chemicals or fish pathogenic bacteria. However, the function of TBT-bps, and the mechanisms of their induction and detoxification activity are still unclear. Here, towards elucidating the functions of TBT-bp2, we produced a TBT-bp2 knockout (TBT-bp2-/-) strain of Japanese medaka, Oryzias latipes, by using the CRISPR/Cas9 system. Gene expression of the mutated TBT-bp2 was reduced, and the cDNA sequencing and predicted protein structure suggested possible loss of function. However, the fish could be grown under normal conditions. Exposure of the TBT-bp2-/- strain of medaka to various stresses in future experiments is expected to contribute to our understanding of this novel detoxification system in aquatic organisms.

Environment-Adaptable Photonic-Electronic-Coupled Neuromorphic Angular Visual System.

Environment-adaptable photonic-electronic-coupled devices can help overcome major challenges related to the extraction of highly specific angular information, such as human visual perception. However, a true implementation of such a device has rarely been investigated thus far. Herein, we provide an approach and demonstrate a proof-of-concept solid-state semiconductor-based highly transparent, optical-electrical-coupled, self-adaptive angular visual perception system that can fulfill the versatile criteria of the human vision system. Specifically, all of the primitive functions of visual perception, such as broad angular sensing, processing, and manifold memory storage, are demonstrated and comodulated using optical and electric pulses. This development represents an essential step forward in the fabrication of an environment-adaptable artificial angular perception framework with deep implications in the fields of optoelectronics, artificial eyes, and memory storage applications.

Analysis of Current Variation with Work Function Variation in L-Shaped Tunnel-Field Effect Transistor.

In this paper, an investigation is performed to analyze the L-shaped tunnel field-effect transistor (TFET) depending on a gate work function variation (WFV) with help of technology computer-aided design (TCAD) simulation. Depending on the gate voltage, the three variations occur in transfer curves. The first one is the on-state current (ION) variation, the second one is the hump current (IHUMP) variation, and the last one is ambipolar current (IAMB) variation. According to the simulation results, the ION variation is sensitive depending on the size of the tunneling region and could be reduced by increasing the tunneling region. However, the IHUMP and IAMB variations are relatively irrelevant to the size of the tunneling region. In order to analyze the cause of this difference, we investigated the band-to-band tunneling (BTBT) rate according to WFV cases. The results show that when ION is formed in L-shaped TFET, the BTBT rate relies on the WFV in the whole region of the gate because the tunnel barrier is formed in the entire area where the source and the gate meet. On the other hand, when the IHUMP and IAMB are formed in L-shaped TFET, the BTBT rate relies on the WFV in the edge of the gate.

Surrounding Channel Nanowire Tunnel Field-Effect Transistor with Dual Gate to Reduce a Hump Phenomenon.

The tunnel field-effect transistor (TFET) with surrounding channel nanowire (SCNW) structure promises better performance than the conventional planar TFET in terms of subthreshold swing (SS) and on-current (ION). In spite of the advantages of SCNW TFET, there are some technical issues in the aspects of a hump phenomenon in subthreshold region and a high ambipolar current (IAMB) in off-state. In order to overcome these issues, a novel dual-gate SCNW TFET (DG-SCNW TFET) with differential gate work functions (WFs) and a gate-drain underlap is proposed and studied by using technology computer-aided design (TCAD) simulation. In addition, a hetero-junction with SiGe source is applied to improve the device performance. Finally, it is confirmed that the optimized DG-SCNW TFET shows the remarkable performance comparing with the control device.

I-Shaped SiGe Fin Tunnel Field-Effect Transistor with High ION/IOFF Ratio.

In this paper, we propose an I-shaped SiGe fin tunnel field-effect transistor (TFET) and use technology computer aided design (TCAD) simulations to verify the validity. Compared to conventional Fin TFET on the same footprint, a 27% increase in the effective channel width can be obtained with the proposed TFET. The proposed Fin TFET was confirmed to have 300% boosted on-current (I on), 25% reduced subthreshold swing (SS), and 52% lower off-current (I off) than conventional Fin TFET through TCAD simulation results. These performance improvements are attributed to increased effective channel width and enhanced gate controllability of the I-shaped fin structure. Furthermore, the fabrication process of forming an I-shaped SiGe fin is also presented using the SiGe wet etch. By optimizing the Ge condensation process, an I-shaped SiGe fin with a Ge ratio greater than 50% can be obtained.

Analysis of Channel Area Fluctuation Effects of Gate-All-Around Tunnel Field-Effect Transistor.

In this manuscript, channel area fluctuation (CAF) effects on turn-on voltage (Von) and subthreshold swing (SS) in gate-all-around (GAA) nanowire (NW) tunnel field-effect transistor (TFET) with multi-bridge-channel (MBC) have been investigated for the first time. These variations occur because oblique etching slope makes various elliptical-shaped channels in MBC-TFET. Since TFET is promising candidates to succeed metal-oxide-semiconductor FETs (MOSFET), these variation effects have been compared to MOSFET. Furthermore, Ge homojunction TFET, one of the solutions to increase on-state current in TFET and improve SS also has been simulated using technology computer-aided design (TCAD) simulation. The results would be worth reference for future study about GAA NW TFETs.

Investigation on Ambipolar Current Suppression Using a Stacked Gate in an L-shaped Tunnel Field-Effect Transistor.

L-shaped tunnel field-effect transistor (TFET) provides higher on-current than a conventional TFET through band-to-band tunneling in the vertical direction of the channel. However, L-shaped TFET is disadvantageous for low-power applications because of increased off-current due to the large ambipolar current. In this paper, a stacked gate L-shaped TFET is proposed for suppression of ambipolar current. Stacked gates can be easily implemented using the structural features of L-shaped TFET, and on- and off-current can be controlled separately by using different gates located near the source and the drain, respectively. As a result, the suppression of ambipolarity is observed with respect to work function difference between two gates by simulation of the band-to-band tunneling generation. Furthermore, the proposed device suppresses ambipolar current better than existing ambipolar current suppression methods. In particular, low drain resistance is achieved as there is no need to reduce drain doping, which leads to a 7% enhanced on-current. Finally, we present the fabrication method for a stacked gate L-shaped TFET.

F-Shaped Tunnel Field-Effect Transistor (TFET) for the Low-Power Application.

In this report, a novel tunnel field-effect transistor (TFET) named 'F-shaped TFET' has been proposed and its electrical characteristics are analyzed and optimized by using a computer-aided design simulation. It features ultra-thin and a highly doped source surrounded by lightly doped regions. As a result, it is compared to an L-shaped TFET, which is a motivation of this work, the F-shaped TFET can lower turn-on voltage (VON) maintaining high on-state current (ION) and low subthreshold swing (SS) with the help of electric field crowding effects. The optimized F-shaped TFET shows 0.4 V lower VON than the L-shaped TFET with the same design parameter. In addition, it shows 4.8 times higher ION and 7 mV/dec smaller average SS with the same VON as that for L-shaped TFET.

Gel Polymer Electrolytes Based on Polymerizable Lithium Salt and Poly(ethylene glycol) for Lithium Battery Applications.

Here, a polymerizable lithium salt, lithium (trifluoromethanesulfonyl)(vinylsulfonyl)imide, was synthesized and used to prepare cross-linked gel polymer electrolyte systems with poly(ethylene glycol) methyl ether methacrylate as an ion-conducting moiety, poly(ethylene glycol) dimethacrylate as a cross-linker, and propylene carbonate as a liquid electrolyte without adding any conventional inorganic lithium salt. The gel polymer electrolytes prepared in this study exhibited a reasonably high ionic conductivity (6.7 × 10-4 S cm-1 at 25 °C and 1.8 × 10-3 S cm-1 at 60 °C) and lithium-ion transference number (0.52), and the lithium battery prepared using the gel polymer electrolyte showed a stable cycling performance over 50 cycles.

Nonvolatile Memory (NVM) Operation of Tunnel Field-Effect Transistor (TFET) Using Ferroelectric HfO2 Sidewall.

In this paper, we propose a new type of nonvolatile memory (NVM) device based on a tunnel field-effect transistor (TFETs) with Ferroelectric HfO2 sidewall. By simply utilizing the ferroelectricity of orthorhombic HfO2 and conventional sidewall spacer technique, TFET can operate as a NVM device. The polarized charges in the ferroelectric HfO2 spacer induced by program/erase pulse modulate the tunneling barrier between the source and channel; thus, change the threshold voltage (Vt) of TFET. The proposed NVM TFET has lower subthreshold swing (SS) and higher on/off ratio than conventional NVM TFETs while maintaining equivalent program/erase efficiency. Further-more, we also investigate the optimal HfO2 sidewall formation conditions to achieve higher NVM performances.

Tunnel Field Effect Transistor with Ferroelectric Gate Insulator.

Ferroelectric tunnel field effect transistor (Fe-TFET) having improved DC performance in comparison to the conventional TFET (c-TFET) is proposed and investigated through the technology computer-aided design (TCAD) simulation. By inserting ferroelectric material into the gate insulator of TFET, enhanced on-current (Ion) is obtained. It is attributed to the polarization characteristic of the ferroelectric materials which brings the capacitance boosting effect. Through the TCAD simulation, the characteristics of the ferroelectric material for the optimal performance conditions are also studied.

Transient Analysis of Tunnel Field-Effect Transistor with Raised Drain.

This paper investigates the electrical performance of a proposed tunnel field-effect transistor (TFET) via transient analysis. The proposed TFET has three features: a SiGe channel, a fin structure, and an elevated drain. As the SiGe channel and fin structure make a small tunnel resistance, the ONstate current can be increased. In addition, an elevated drain can suppress an ambipolar current (IAMB). The transient characteristics should be confirmed in terms of inverter switching for the high applicability of the proposed device to the logical circuit. The analysis is verified through technology computer-aided design (TCAD) simulations calibrated with rigorously fabricated devices. Based on the simulation results, we conclude that the proposed TFET shows better ON/OFF transient characteristics when compared to conventional TFETs and the small gate-to-drain capacitance (CGD) can improve the transient characteristics in TFET.

Design Optimization of Double-Gate Isosceles Trapezoid Tunnel Field-Effect Transistor (DGIT-TFET).

Recently, tunnel field-effect transistors (TFETs) have been regarded as next-generation ultra-low-power semi-conductor devices. To commercialize the TFETs, however, it is necessary to improve an on-state current caused by tunnel-junction resistance and to suppress a leakage current from ambipolar current (IAMB). In this paper, we suggest a novel TFET which features double gate, vertical, and trapezoid isosceles channel structure to solve the above-mentioned technical issues. The device design is optimized by examining its electrical characteristics with the help of technology computer-aided design (TCAD) simulation. As a result, double-gate isosceles trapezoid (DGIT) TFET shows a much better performance than the conventional TFET in terms of ON-state current (ION), IAMB, and gate-to-drain capacitance (CGD). It is confirmed that an inverter composed of DGIT-TFETs can operate with less than 1 ns intrinsic delay time and negligible voltage overshoot.

Pulp-dentin regeneration: current approaches and challenges.

Regenerative endodontic procedures for immature permanent teeth with apical periodontitis confer biological advantages such as tooth homeostasis, enhanced immune defense system, and a functional pulp-dentin complex, in addition to clinical advantages such as the facilitation of root development. Currently, this procedure is recognized as a paradigm shift from restoration using materials to regenerate pulp-dentin tissues. Many studies have been conducted with regard to stem/progenitor cells, scaffolds, and biomolecules, associated with pulp tissue engineering. However, preclinical and clinical studies have evidently revealed several drawbacks in the current clinical approach to revascularization that may lead to unfavorable outcomes. Therefore, our review examines the challenges encountered under clinical conditions and summarizes current research findings in an attempt to provide direction for transition from basic research to clinical practice.

High On-Current Ge-Channel Heterojunction Tunnel Field-Effect Transistor Using Direct Band-to-Band Tunneling.

The main challenge for tunnel field-effect transistors (TFETs) is achieving high on-current (Ion) and low subthreshold swing (SS) with reasonable ambipolar characteristics. In order to address these challenges, Ge-channel heterostructure TFET with Si source and drain region is proposed, and its electrical characteristics are compared to other TFET structures. From two-dimensional (2-D) device simulation results, it is confirmed that the Si/Ge heterostructure source junction improves Ion and SS characteristics by using the direct band-to-band tunneling current. Furthermore, the proposed structure shows suppressed ambipolar behavior since the Ge/Si heterostructure is used at the drain junction.