Quantitative analysis of defect states in InGaZnO within 2 eV below the conduction band via photo-induced current transient spectroscopy.

This work investigates the function of the oxygen partial pressure in photo-induced current measurement of extended defect properties related to the distribution and quantity of defect states in electronic structures. The Fermi level was adjusted by applying a negative gate bias in the TFT structure, and the measurable range of activation energy was extended to < 2.0 eV.

Approaches for 3D Integration Using Plasma-Enhanced Atomic-Layer-Deposited Atomically-Ordered InGaZnO Transistors with Ultra-High Mobility.

As the scale-down and power-saving of silicon-based channel materials approach the limit, oxide semiconductors are being actively researched for applications in 3D back-end-of-line integration. For these applications, it is necessary to develop stable oxide semiconductors with electrical properties similar to those of Si. Herein, a single-crystal-like indium-gallium-zinc-oxide (IGZO) layer (referred to as a pseudo-single-crystal) is synthesized using plasma-enhanced atomic layer deposition and fabricated stable IGZO transistors with an ultra-high mobility of over 100 cm  Vs .

High Mobility IZTO Thin-Film Transistors Based on Spinel Phase Formation at Low Temperature through a Catalytic Chemical Reaction.

In this paper, In Zn Sn O (δ = 0.55) films with a single spinel phase are successfully grown at the low temperature of 300 °C through careful cation composition design and a catalytic chemical reaction. Thin-film transistors (TFTs) with amorphous In Zn Sn O (δ = 0.

Hydrogen-Doping-Enabled Boosting of the Carrier Mobility and Stability in Amorphous IGZTO Transistors.

This study investigated the effect of hydrogen (H) on the performance of amorphous In-Ga-Zn-Sn oxide (-InGaZnSnO) thin-film transistors (TFTs). Ample H in plasma-enhanced atomic layer deposition (PEALD)-derived SiO can diffuse into the underlying -IGZTO film during the postdeposition annealing (PDA) process, which affects the electrical properties of the resulting TFTs due to its donor behavior in the -IGZTO. The -InGaZnSnO TFTs at the PDA temperature of 400 °C exhibited a remarkably higher field-effect mobility (μ) of 85.

Tailored Self-Assembled Monolayer using Chemical Coupling for Indium-Gallium-Zinc Oxide Thin-Film Transistors: Multifunctional Copper Diffusion Barrier.

Controlling the contact properties of a copper (Cu) electrode is an important process for improving the performance of an amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) for high-speed applications, owing to the low resistance-capacitance product constant of Cu. One of the many challenges in Cu application to a-IGZO is inhibiting high diffusivity, which causes degradation in the performance of a-IGZO TFT by forming electron trap states. A self-assembled monolayer (SAM) can perfectly act as a Cu diffusion barrier (DB) and passivation layer that prevents moisture and oxygen, which can deteriorate the TFT on-off performance.

High-performance hysteresis-free perovskite transistors through anion engineering.

Despite the impressive development of metal halide perovskites in diverse optoelectronics, progress on high-performance transistors employing state-of-the-art perovskite channels has been limited due to ion migration and large organic spacer isolation. Herein, we report high-performance hysteresis-free p-channel perovskite thin-film transistors (TFTs) based on methylammonium tin iodide (MASnI) and rationalise the effects of halide (I/Br/Cl) anion engineering on film quality improvement and tin/iodine vacancy suppression, realising high hole mobilities of 20 cm V s, current on/off ratios exceeding 10, and threshold voltages of 0 V along with high operational stabilities and reproducibilities. We reveal ion migration has a negligible contribution to the hysteresis of Sn-based perovskite TFTs; instead, minority carrier trapping is the primary cause.

Development of Three-Stage Bioaerosol Sampler for Size-Selective Sampling.

In this study, a three-stage bio-aerosol sampler with a sampling flow rate of 170 L/min was designed and fabricated for sampling the bio-aerosols released during human breathing and coughing, and its performance was evaluated. The sampler was constructed using a cyclone separator with a cutoff size of 2.5 μm as a preseparator, a multinozzle virtual impactor with a cutoff size of 0.

Development of a high-volume ambient aerosol sampling inlet with an adjustable cutoff size and its performance evaluation using road dust.

Aerosol samplers are generally classified into particulate matter (PM or PM) and total suspended particle (TSP) samplers. As changing the cutoff size is cumbersome, it necessitates either replacing the particle size separator or adjusting the sampling flow rate. In this study, a novel high-volume aerosol-sampling inlet with an adjustable cutoff size was developed.

High-volume sampler for size-selective sampling of bioaerosols including viruses.

Owing to the recent global spread of the new coronavirus SARS-CoV-2, the development of technology to effectively detect viruses in crowded public places is urgently needed. In this study, a three-stage high-volume bioaerosol sampler was developed for the size-selective sampling of bioaerosols through the suction of air at a high flow rate of 1000 L/min. In stage 1, an omnidirectional inlet cyclone separator that can draw air from all directions was applied to collect bioaerosols larger than 10 μm in the collection fluid.

Multifunctional Oxygen Scavenger Layer for High-Performance Oxide Thin-Film Transistors with Low-Temperature Processing.

In this study, the oxygen scavenger layer (OSL) is proposed as a back channel in the bilayer channel to enhance both the electrical characteristics and stability of an amorphous indium-gallium-zinc oxide thin-film transistor (a-IGZO TFT) and also to enable its fabrication at low temperature. The OSL is a hafnium (Hf)-doped a-IGZO channel layer deposited by radio-frequency magnetron cosputtering. Amorphous IGZO TFTs with the OSL, even if annealed at a low temperature (200 °C), exhibited improved electrical characteristics and stability under positive bias temperature stress (PBTS) compared to those without the OSL, specifically in terms of field-effect mobility (31.

Significance of Pairing In/Ga Precursor Structures on PEALD InGaO Thin-Film Transistor.

Atomic layer deposition (ALD) is a promising deposition method to precisely control the thickness and metal composition of oxide semiconductors, making them attractive materials for use in thin-film transistors because of their high mobility and stability. However, multicomponent deposition using ALD is difficult to control without understanding the growth mechanisms of the precursors and reactants. Thus, the adsorption and surface reactivity of various precursors must be investigated.

Botulinum Toxin A Ameliorates Neuroinflammation in the MPTP and 6-OHDA-Induced Parkinson's Disease Models.

Recently, increasing evidence suggests that neuroinflammation may be a critical factor in the development of Parkinson's disease (PD) in addition to the ratio of acetylcholine/dopamine because dopaminergic neurons are particularly vulnerable to inflammatory attack. In this study, we investigated whether botulinum neurotoxin A (BoNT-A) was effective for the treatment of PD through its anti-neuroinflammatory effects and the modulation of acetylcholine and dopamine release. We found that BoNT-A ameliorated MPTP and 6-OHDA-induced PD progression, reduced acetylcholine release, levels of IL-1β, IL-6 and TNF-α as well as GFAP expression, but enhanced dopamine release and tyrosine hydroxylase expression.

Boosting carrier mobility and stability in indium-zinc-tin oxide thin-film transistors through controlled crystallization.

We investigated the effect of film thickness (geometrical confinement) on the structural evolution of sputtered indium-zinc-tin oxide (IZTO) films as high mobility n-channel semiconducting layers during post-treatment at different annealing temperatures ranging from 350 to 700 °C. Different thicknesses result in IZTO films containing versatile phases, such as amorphous, low-, and high-crystalline structures even after annealing at 700 °C. A 19-nm-thick IZTO film clearly showed a phase transformation from initially amorphous to polycrystalline bixbyite structures, while the ultra-thin film (5 nm) still maintained an amorphous phase.

High Photosensitive Indium-Gallium-Zinc Oxide Thin-Film Phototransistor with a Selenium Capping Layer for Visible-Light Detection.

Visible light can be detected using an indium-gallium-zinc oxide (IGZO)-based phototransistor, with a selenium capping layer (SCL) that functions as a visible light absorption layer. Selenium (Se) exhibits photoconductive properties as its conductivity increases with illumination. We report an IGZO phototransistor with an SCL (SCL/IGZO phototransistor) that demonstrated optimal photoresponse characteristics when the SCL was 150 nm thick.

Design of InZnSnO Semiconductor Alloys Synthesized by Supercycle Atomic Layer Deposition and Their Rollable Applications.

Amorphous InGaZnO semiconductors have been rapidly developed as active charge-transport materials in thin film transistors (TFTs) because of their cost effectiveness, flexibility, and homogeneous characteristics for large-area applications. Recently, InZnSnO (IZTO) with superior mobility (higher than 20 cm V s) has been suggested as a promising oxide semiconductor material for high-resolution, large-area displays. However, the electrical and physical characteristics of IZTO have not been fully characterized.

Effect of Annealing Temperature on Morphology and Electrical Property of Hydrothermally-Grown ZnO Nanorods/-Si Heterojunction Diodes.

In this study, ZnO nanorods (NRs) were synthesized using the hydrothermal method, and the effects of annealing temperature (150 °C-600 °C) on morphology, crystallinity, defects states of the NRs, and electrical property of the -type ZnO NRs/-type Si heterojunction diodes were investigated. No appreciable changes in the morphology and crystal structure of the ZnO NRs were observed with increasing annealing temperature up to 450 °C. As the temperature increased to 600 °C, the average length and diameter of the NRs decreased due to the partial melting and sintering in the NRs.

Low-temperature synthesis of 2D MoS on a plastic substrate for a flexible gas sensor.

The efficient synthesis of two-dimensional molybdenum disulfide (2D MoS2) at low temperatures is essential for use in flexible devices. In this study, 2D MoS2 was grown directly at a low temperature of 200 °C on both hard (SiO2) and soft substrates (polyimide (PI)) using chemical vapor deposition (CVD) with Mo(CO)6 and H2S. We investigated the effect of the growth temperature and Mo concentration on the layered growth by Raman spectroscopy and microscopy.

Photothermally Activated Nanocrystalline Oxynitride with Superior Performance in Flexible Field-Effect Transistors.

Photochemical reactions in inorganic films, which can be promoted by the addition of thermal energy, enable significant changes in the properties of films. Metaphase films depend significantly on introducing external energy, even at low temperatures. We performed thermal-induced, deep ultraviolet-based, thermal-photochemical activation of metaphase ZnON films at low temperature, and we observed peculiar variations in the nanostructures with phase transformation and densification.

Synergistic effect of Indium and Gallium co-doping on growth behavior and physical properties of hydrothermally grown ZnO nanorods.

We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In) and smaller (Ga) than the host Zn cations.

Effect of AlO Deposition on Performance of Top-Gated Monolayer MoS-Based Field Effect Transistor.

Deposition of high-k dielectrics on two-dimensional MoS is an important process for successful application of the transition-metal dichalcogenides in electronic devices. Here, we show the effect of HO reactant exposure on monolayer (1L) MoS during atomic layer deposition (ALD) of AlO. The results showed that the ALD-AlO caused degradation of the performance of 1L MoS field effect transistors (FETs) owing to the formation of Mo-O bonding and trapping of HO molecules at the AlO/MoS interface.

Facet-controlled anatase TiO2 nanoparticles through various fluorine sources for superior photocatalytic activity.

Reactive surface-exposed anatase TiO2 (a-TiO2) is highly desirable for applications requiring superior photocatalytic activity. In order to obtain a favorable surface, morphology control of the a-TiO2 using capping agents has been widely investigated. Herein, we systematically study the effects of different F sources (HF, TiF4, and NH4F) as the capping agent on the morphology control and photocatalytic activities of a-TiO2 in a hydrothermal process.

Hydrothermally Grown In-doped ZnO Nanorods on p-GaN Films for Color-tunable Heterojunction Light-emitting-diodes.

The incorporation of doping elements in ZnO nanostructures plays an important role in adjusting the optical and electrical properties in optoelectronic devices. In the present study, we fabricated 1-D ZnO nanorods (NRs) doped with different In contents (0% ~ 5%) on p-GaN films using a facile hydrothermal method, and investigated the effect of the In doping on the morphology and electronic structure of the NRs and the electrical and optical performances of the n-ZnO NRs/p-GaN heterojunction light emitting diodes (LEDs). As the In content increased, the size (diameter and length) of the NRs increased, and the electrical performance of the LEDs improved.

Surface-Tunable Bioluminescence Resonance Energy Transfer via Geometry-Controlled ZnO Nanorod Coordination.

The use of ZnO nanorods (NRs) as an effective coordinator and biosensing platform to create bioluminescence resonance energy transfer (BRET) is reported. Herein, a hydrothermal approach is applied to obtain morphologically controlled ZnO NRs, which are directly bound to luciferase (Luc) and carboxy-modified quantum dot (QD) acting as a donor-acceptor pair for BRET. BRET efficiency varies significantly with the geometry of ZnO NRs, which modulates the coordination between hexahistidine-tagged Luc (Luc-His6 ) and QD, owing to the combined effect of the total surface area consisting of (001) and (100) planes and their surface polarities.

Growth behavior and electrical performance of Ga-doped ZnO nanorod/p-Si heterojunction diodes prepared using a hydrothermal method.

The incorporation of foreign elements into ZnO nanostructures is of significant interest for tuning the structure and optical and electrical properties in nanoscale optoelectronic devices. In this study, Ga-doped 1-D ZnO nanorods were synthesized using a hydrothermal route, in which the doping content of Ga was varied from 0% to 10%. The pn heterojunction diodes based on the n-type Ga-doped ZnO nanorod/p-type Si substrates were constructed, and the effect of the Ga doping on the morphology, chemical bonding structure, and optical properties of the ZnO nanorods was systematically investigated as well as the diode performance.

Fabrication of solution-processed InSnZnO/ZrO2 thin film transistors.

We fabricated InSnZnO (ITZO) thin-film transistors (TFTs) with a high-permittivity (K) ZrO2 gate insulator using a solution process and explored the microstructure and electrical properties. ZrO2 and ITZO (In:Sn:Zn = 2:1:1) precursor solutions were deposited using consecutive spin-coating and drying steps on highly doped p-type Si substrate, followed by annealing at 700 degrees C in ambient air. The ITZO/ZrO2 TFT device showed n-channel depletion mode characteristics, and it possessed a high saturation mobility of approximately 9.