Improved Performance and Bias Stability of Al2O3/IZO Thin-Film Transistors with Vertical Diffusion

Several studies on amorphous oxide semiconductor thin-film transistors (TFTs) applicable to next-generation display devices have been conducted. To improve the poor switching characteristics and gate bias stability of co-sputtered aluminum–indium–zinc oxide (AIZO) TFTs, we fabricate Al2O3/indium–zinc oxide (IZO) dual-active-layer TFTs. By varying the Al2O3 target power and oxygen partial pressure in the chamber during Al2O3 back-channel deposition, we optimize the electrical characteristics and gate bias stability of the Al2O3/IZO TFTs. The Al2O3/IZO TFTs, which are fabricated under 50 W Al2O3 target power and 13% oxygen partial pressure conditions, exhibit a high electron mobility of 23.34 cm2/V·s, a low threshold voltage of 0.96 V, an improved on–off current ratio of 6.8 × 107, and a subthreshold swing of 0.61 V/dec. Moreover, by increasing the oxygen partial pressure in the chamber, the positive and negative bias stress values improve to +0.32 V and −2.08 V, respectively. X-ray photoelectron spectroscopy is performed to reveal the cause of these improvements

Recent Advancements in Polysulfone Based Membranes for Fuel Cell (PEMFCs, DMFCs and AMFCs) Applications: A Critical Review

In recent years, ion electrolyte membranes (IEMs) preparation and properties have attracted fabulous attention in fuel cell usages owing to its high ionic conductivity and chemical resistance. Currently, perfluorinatedsulfonicacid (PFSA) membrane has been widely employed in the membrane industry in polymer electrolyte membrane fuel cells (PEMFCs); however, NafionTM suffers reduced proton conductivity at a higher temperature, requiring noble metal catalyst (Pt, Ru, and Pt-Ru), and catalyst poisoning by CO. Non-fluorinated polymers are a promising substitute. Polysulfone (PSU) is an aromatic polymer with excellent characteristics that have attracted membrane scientists in recent years. The present review provides an up-to-date development of PSU based electrolyte membranes and its composites for PEMFCs, alkaline membrane fuel cells (AMFCs), and direct methanol fuel cells (DMFCs) application. Various fillers encapsulated in the PEM/AEM moiety are appraised according to their preliminary characteristics and their plausible outcome on PEMFC/DMFC/AMFC. The key issues associated with enhancing the ionic conductivity and chemical stability have been elucidated as well. Furthermore, this review addresses the current tasks, and forthcoming directions are briefly summarized of PEM/AEMs for PEMFCs, DMFCs, AMFCs

Effects of Yttrium Doping on a-IGZO Thin Films for Use as a Channel Layer in Thin-Film Transistors

Amorphous In−Ga−Zn−O (a-IGZO) has been studied as a channel layer in thin-film transistors (TFTs). To improve the bias-induced instability of a-IGZO TFTs, we introduced yttrium with high bond enthalpy by magnetron co-sputtering system. The Y-doped a-IGZO (a-IGZO:Y) films show relatively lower carrier concentration and higher Hall mobility, which is due to the suppression of oxygen vacancies caused by Y doping. The a-IGZO:Y showed a relatively higher transmittance in the visible light region compared to non-doped IGZO, which could be due to the decrease of shallow defect levels caused by oxygen vacancy in the band gap. The a-IGZO without Y doping showed dramatic changes in electrical properties as times progressed (over 240 h); however, the a-IGZO:Y showed no significant changes. The a-IGZO:Y TFTs demonstrated a more stable driving mode as exhibited in the positive gate bias stress test even though the values of VTH and SS were slightly degraded

Performance Improvement of ZnSnO Thin-Film Transistors with Low-Temperature Self-Combustion Reaction

Conventional sol-gel solutions have received significant attention in thin-film transistor (TFT) manufacturing because of their advantages such as simple processing, large-scale applicability, and low cost. However, conventional sol-gel processed zinc tin oxide (ZTO) TFTs have a thermal limitation in that they require high annealing temperatures of more than 500 °C, which are incompatible with most flexible plastic substrates. In this study, to overcome the thermal limitation of conventional sol-gel processed ZTO TFTs, we demonstrated a ZTO TFT that was fabricated at low annealing temperatures of 350 °C using self-combustion. The optimized device exhibited satisfactory performance, with μsat of 4.72 cm2/V∙s, Vth of −1.28 V, SS of 0.86 V/decade, and ION/OFF of 1.70 × 106 at a low annealing temperature of 350 °C for one hour. To compare a conventional sol-gel processed ZTO TFT with the optimized device, thermogravimetric and differential thermal analyses (TG-DTA) and X-ray photoelectron spectroscopy (XPS) were implemented

Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively

Improved Sensitivity of α-Fe₂O₃ Nanoparticle-Decorated ZnO Nanowire Gas Sensor for CO

A strategy for improving the sensitivity of a sensor for detecting CO and NH3 gases is presented herein. The gas sensor was fabricated from ZnO metal oxide semiconductor nanostructures grown via a vapor–liquid–solid process and decorated with α-Fe2O3 nanoparticles via a sol–gel process. The response was enhanced by the formation of an α-Fe2O3/ZnO n–n heterojunction and the growth of thinner wires. ZnO nanowires were grown on indium–tin–oxide glass electrodes using Sn as a catalyst for growth instead of Au. The structure and elemental composition were investigated using field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The gas sensing results indicate that the response value to 100 ppm CO was 18.8 at the optimum operating temperature of 300 °C

Fabrication of High-Performance Asymmetric Supercapacitor Consists of Nickel Oxide and Activated Carbon (NiO//AC)

Exploring faster, safer, and more efficient energy storage devices will motivate scientists to develop novel energy storage products with high performance. Herein, we report porous NiO nanoparticles have been prepared by a simple hydrothermal method with CTAB and laboratory tissue paper as a template followed by calcination at three different temperatures (300, 500, and 700 °C). The electrochemical characteristics of the prepared materials were examined in a three-electrode cell configuration using aqueous potassium hydroxide (2.0 M KOH) electrolyte. The NiO-300 electrode displayed the supreme capacitance of 568.7 F g−1 at 0.5 A g−1. The fascinating NiO morphology demonstrates a crucial part in offering simple ion transport, shortening electron, and ion passage channels and rich energetic spots for electrochemical reactions. Finally, the asymmetric supercapacitor (ASC), NiO//AC was constructed using positive and negative electrode materials of NiO-300 and activated carbon (AC), respectively. The assembled ASC displayed excellent supercapacitive performance with a high specific energy (52.4 Wh kg−1), specific power (800 W kg−1), and remarkable cycle life. After quick charging (25 s), such supercapacitors in the series will illuminate the light emitting diode for an extended time, suggesting improvements in energy storage, scalable integrated applications, and ensuring business efficacy. This work will lead to a new generation of high-performance ASCs to portable electronic displays and electric automobiles

Effects of Double Active Layer and Acetic Acid Stabilizer on the Electrical Properties of a Solution-Processed Zinc Tin Oxide Thin-Film Transistor

We investigated the effects of a double active layer (DAL) and acetic acid stabilizer on zinc tin oxide (ZTO) thin-film transistors (TFTs) fabricated using a solution process. The DAL was composed of two layers created by a ZTO solution doped with the same or different percentiles of an atomic Sn concentration (30 at.%, 60 at.%). The electrical performance of the ZTO TFTs significantly was improved after we added acetic acid (AA) instead of monoethanolamine (MEA). This was accomplished by applying a type 2 DAL (bottom layer: Sn 60 at.%, top layer: Sn 30 at.%, 60/30) instead of other types (30/30 or 60/60). It was demonstrated that AA plays a role in lowering the decomposition temperature, enhancing the metal-oxygen bridge, and decreasing hydroxyl groups in the film. In addition, the type 2 DAL structure (60/30) lowered the I-off of the ZTO TFT and controlled the carrier concentration in the channel. The best performances were obtained at a Sn concentration of 60 at.% in the bottom ZTO layer and 30 at.% in the top ZTO layer, with AA added as a stabilizer. The ZTO TFT exhibited an on/off ratio of 1.1 x 10(9), a saturation mobility of 5.04 cm(2)/V.s, a subthreshold slope of 0.11 V/decade, and a threshold voltage of 1.6 V

Fabrication of High-Performance Asymmetric Supercapacitor Consists of Nickel Oxide and Activated Carbon (NiO//AC)

Exploring faster, safer, and more efficient energy storage devices will motivate scientists to develop novel energy storage products with high performance. Herein, we report porous NiO nanoparticles have been prepared by a simple hydrothermal method with CTAB and laboratory tissue paper as a template followed by calcination at three different temperatures (300, 500, and 700 °C). The electrochemical characteristics of the prepared materials were examined in a three-electrode cell configuration using aqueous potassium hydroxide (2.0 M KOH) electrolyte. The NiO-300 electrode displayed the supreme capacitance of 568.7 F g−1 at 0.5 A g−1. The fascinating NiO morphology demonstrates a crucial part in offering simple ion transport, shortening electron, and ion passage channels and rich energetic spots for electrochemical reactions. Finally, the asymmetric supercapacitor (ASC), NiO//AC was constructed using positive and negative electrode materials of NiO-300 and activated carbon (AC), respectively. The assembled ASC displayed excellent supercapacitive performance with a high specific energy (52.4 Wh kg−1), specific power (800 W kg−1), and remarkable cycle life. After quick charging (25 s), such supercapacitors in the series will illuminate the light emitting diode for an extended time, suggesting improvements in energy storage, scalable integrated applications, and ensuring business efficacy. This work will lead to a new generation of high-performance ASCs to portable electronic displays and electric automobiles