Recently, hafnia ferroelectrics with two spontaneous polarization states have attracted marked attention for non-volatile, super-steep switching devices, and neuromorphic application due to their ...fast switching, scalability, and CMOS compatibility. However, field cycling-induced instabilities are a serious obstacle in the practical application of various low-power electronic devices that require a settled characteristic of polarization hysteresis. In this work, a large reduction in the field cycling-induced instabilities and significantly improved ferroelectric properties were observed in a Hf
0.5
Zr
0.5
O
2
(HZO) thin film with a RuO
2
oxide electrode. The oxide electrode can supply additional oxygen to the HZO film, consequently minimizing the oxygen vacancies at the interface which is the origin of low reliability. From the material and electrical analysis results, we verified that HZO with the RuO
2
electrode has less non-ferroelectric dead layers and fewer oxygen vacancies at the interface, resulting in excellent switching properties and improved reliability. This result suggests a beneficial method to produce high-quality hafnia thin films free from interfacial defects and with stable field cycling electrical properties for actual applications.
Recently, hafnia ferroelectrics with two spontaneous polarization states have attracted marked attention for non-volatile, super-steep switching devices, and neuromorphic application due to their fast switching, scalability, and CMOS compatibility.
A predominant factor of the diffusion‐controlled kinetics of a solid‐state addition reaction using powder is the particle size of the reactants, into which the other chemical species are migrating. ...However, diffusion‐controlled kinetic equations are seldom satisfactorily applicable even when the effects of particle size are thoroughly accounted. One of the representative nongeometrical items affecting the solid‐state reaction process is the reactivity of solids (ROS), which has not been accounted in any of the established kinetic equations. Change in ROS is the consequence of the imperfections of the crystalline solids. In this study, we try to discuss the effects of ROS on the solid‐state reaction kinetics. A typical solid‐state addition reaction, formation of BaTiO3 from the equimolar mixture of TiO2 and BaCO3, was chosen as a model. For this reaction, the rate‐determining step is established to be the diffusion of Ba2+ ions into TiO2. Since the defect concentration is known to be higher at the near‐surface region, the local distribution of ROS that is discussed here is based on a simple core‐shell model of the host TiO2 particles with higher reactivity at the shell part. The ratio of the rate of diffusion within the shell part relative to that of the core (factor n), and the ratio of shell thickness, Rs, relative to the particle radius, Rp, (factor g) were chosen as main parameters to be iterated. By systematically varying these two factors, n and g, we succeeded in minimizing the fluctuation of apparent diffusion rate constant by the particle size. Despite the oversimplified model and lacking experimental evidences of the hypothetical parameters, the present proposal may pave the way to introduce ROS and its local distribution into the reaction kinetics. We also discussed the effects of second phases by comparing the same reaction process observed from the decomposition of the reactant and formation of the products.
Apparent rate of diffusion of Ba2+ into TiO2 particle is faster at the shell part due to higher lattice defect concentration than the core part.
Microplastic contamination in marine organisms is a growing environmental issue with implications for seafood safety. Among marine organisms, shellfish are considered to be an important route of ...human exposure to microplastics because they filter a large volume of seawater while feeding and, thus, accumulate microplastics from seawater; furthermore, they are consumed whole, without gut removal. In this study, a market survey was carried out to understand microplastic contamination in domestic bivalves sold in fishery markets in three major cities of South Korea. Four popular bivalve species, oyster (Crassostrea gigas), mussel (Mytilus edulis), Manila clam (Tapes philippinarum) and scallop (Patinopecten yessoensis), were selected as monitoring species, which together account for 79–84% of total shellfish consumption in Korea. The mean concentration of microplastics in these four species was 0.15 ± 0.20 n/g and 0.97 ± 0.74 n/individual. Fragments and particles smaller than 300 μm were dominant shape and size, accounting for 76% and 65% of total microplastics, respectively. Polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyester were the major polymer types. Interestingly, differing polymer compositions were observed according to the culture methods and habitat characteristics of each species. PS was found in high proportions in oysters and mussels cultured in the upper layer of the water column, while the proportions decreased and those of polyester increased in Manila clams and scallops that were cultured in intertidal sediments or the middle and bottom layers of the water column. The annual dietary intake of microplastics by the Korean population via shellfish consumption was estimated as 212 n/person·year. Our results suggested that microplastic pollution is widespread in commercial bivalves and we recommend a systematic and integrative market-basket survey to clarify the current status of human exposure to microplastics.
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•Microplastic (MP) contamination in bivalves purchased from markets was studied.•MP contamination was widespread in market bivalves.•Shape and polymer type of MP were influenced by farming method of each species.•The dietary intake of MP by the Korean population via shellfish was estimated.•Seafood consumption can be a route of MP exposure for humans.
Microplastic contamination in market bivalves from South Korea was investigated to understand human exposure to microplastics via seafood consumption.
We fabricated amorphous InGaZnO thin film transistors (a-IGZO TFTs) with aluminum oxide (Al
O
) as a gate insulator grown through atomic layer deposition (ALD) method at different deposition ...temperatures (
). The Al
O
gate insulator with a low
exhibited a high amount of hydrogen in the film, and the relationship between the hydrogen content and the electrical properties of the TFTs was investigated. The device with the Al
O
gate insulator having a high H content showed much better transfer parameters and reliabilities than the low H sample. This is attributed to the defect passivation effect of H in the active layer, which is diffused from the Al
O
layer. In addition, according to the post-annealing temperature (
), a-IGZO TFTs exhibited two unique changes of properties; the degradation in low
and the enhancement in high
, as explained in terms of H diffusion from the gate insulator to an active layer.
Bivalves are useful bioindicators of microplastic contamination in the marine environment for several reasons, such as extensive filter feeding activity, broad geographical distribution, and limited ...movement capability. This study conducted a nationwide monitoring of microplastic pollution along the Korean coasts using filter-feeding bivalves (including oyster, mussel, and Manila clam) as bioindicators to identify the national contamination level and characteristics of microplastics. Seawater sample was collected from the same sampling stations of oyster and mussel for comparison. Microplastics were widely distributed in both coastal bivalves and waters with mean concentrations of 0.33 ± 0.23 n/g (1.21 ± 0.68 n/individual) in oyster/mussel, 0.43 ± 0.32 n/g (2.19 ± 1.20 n/individual) in Manila clam, and 1400 ± 560 n/m3 in seawater. Despite the lack of significant relationship in the abundance of microplastics, their dominant features such as size, shape, color and polymer type were similar between bivalves and seawater. Fragments (69% for oyster/mussel, 72% for Manila clam, and 77% for seawater), particles smaller than 300 μm (96% for oyster/mussel, 83% for Manila clam, and 84% for seawater) and colorless (79% for oyster/mussel, 85% for Manila clam, 75% for seawater) were the dominant shape, size and color, respectively. The major polymer types were polypropylene, polyethylene, and polyester. The microplastic level in bivalves was relatively high in urbanized areas with a wide diversity of polymer types compared with those in non-urbanized areas, and the proportion of polystyrene in the Korean samples was abundant compared with other regions due to wide use of polystyrene products in Korea. Our result suggests that microplastic contamination is widespread in the Korean coastal environment, and bivalves can reflect the microplastic pollution characteristics of the surrounding waters where they live.
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•Microplastic (MP) was widespread in bivalves and seawater from the Korea coasts.•Size, shape, and polymer type were similar between bivalves and nearby seawater.•Bivalves from urbanized areas exhibited high abundance and diversity of MP.
A nationwide biomonitoring study was conducted to identify the national contamination level and characteristics of microplastics in Korea.
The “short‐circuit effect” in the fire‐through Ag metallization of crystalline Si (c‐Si) solar cells refers to the poor contact formation caused by an electrical short between the Ag gridline and ...underlying Si emitter during contact firing. This study employs two different Ag pastes containing PbO‐ and TeO2‐based glass frits to investigate the dependence of the short‐circuit effect on the length and pattern of the Ag finger lines. The results show that regardless of the employed glass frits, the short‐circuit effect is mitigated even near the short spot and gradually attenuated along the finger line away from the spot as the Ag finger line extends radially longer than the critical length (>35 mm). We demonstrate that this attenuation is independent of the finger line width and predominantly attributed to the ohmic drop of the electrode potential along the Si substrate. The results also show that, regardless of the glass frits, the contact quality is strongly correlated with the density of the Ag crystallites that are formed on the Si emitter surface. The 6‐in full‐cell tests indicate that the isolation of the short spots by segmenting the Ag finger lines does not necessarily result in the mitigation of the short‐circuit effect. We suggest that the reduction of Ag+ on the Si emitter surface should be the key process that must be controlled to achieve high‐quality contacts during contact firing, providing further insights into the electrochemical characteristics of contact firing reactions for the future development of Ag pastes.
The electrochemical nature of the contact firing reactions is studied by short‐circuiting the Ag fingers to the underlying Si emitter. The short‐circuit effect is gradually attenuated along the finger line away from the short‐spot owing to the ohmic drop of the electrode potential along the Si substrate. The contact quality is strongly correlated to the Ag crystallites formed on the emitter surface. The 6‐in full‐cell tests demonstrate that the segmentation of Ag fingers does not necessarily mitigate the short‐circuit effect.
Human activity is thought to affect the abundance and contamination characteristics of microplastics (MPs) in the environment, which may in turn affect aquatic species. However, few studies have ...examined the impact of coastal area use pattern on characteristics of MPs in coastal regions. In this study, we investigated MP contamination of abiotic matrices (seawater and sediment) and biotic matrices (bivalves and polychaetes) in three coastal regions characterized by different types of human activity, covering urban, aquafarm, and rural areas. MP abundance was higher in sediment from the urban site than in that from the rural site, but similar to that from the aquafarm site. In the abiotic matrices, different MP polymer compositions were observed among the three sites. Diverse polymers were found in marine matrices from the urban site, implying diverse MP sources in highly populated and industrialized areas. Polystyrene was more abundant in the aquafarm site, reflecting the wide use of expanded polystyrene aquaculture buoys. Polypropylene was more abundant at the rural site, probably due to the use of polypropylene ropes and nets in fishing activity. MP accumulation profiles in marine invertebrates showed trends similar to those exhibited by abiotic matrices, reflecting coastal area use patterns. These results indicate that marine MPs are generated from both land- and marine-based sources, and that the abiotic and biotic marine matrices reflect the MP characteristics.
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•Microplastic (MP) contamination was compared in urban, aquafarm, and rural areas.•MP shape, size, and polymer type were examined in various marine matrices.•Coastal area use pattern and MP contamination were found to be closely related.•Diverse polymers were found in marine matrices, creek, and road dust from urban.•Marine-based activities are important contributors to MP contamination.
The phase III AXEPT study showed the noninferiority of modified capecitabine plus irinotecan (mXELIRI) with or without bevacizumab relative to fluorouracil, leucovorin, and irinotecan (FOLFIRI) with ...or without bevacizumab as a second‐line treatment for metastatic colorectal cancer. We evaluated the associations between the UGT1A1 genotype linked to adverse events—caused by irinotecan—and the efficacy and safety of mXELIRI and FOLFIRI. The UGT1A1 genotype was prospectively determined and patients were categorized into three groups according to WT (*1/*1), single heterozygous (SH; *28/*1 or *6/*1), and double heterozygous or homozygous (DHH; *28/*28, *6/*6, or *28/*6). Overall survival (OS), progression‐free survival, response rate, and safety were assessed. The UGT1A1 genotype was available in all 650 randomized patients (WT, 309 47.5%; SH, 291 44.8%; DHH, 50 7.7%). The median OS was 15.9, 17.7, and 10.6 months in the WT, SH, and DHH groups, respectively, with an adjusted hazard ratio (HR) of 1.53 (95% confidence interval CI, 1.12‐2.09; P = .008) for DHH vs WT or SH. The median OS in the mXELIRI and FOLFIRI arms was 18.1 vs 14.3 months (HR 0.80; 95% CI, 0.62‐1.03) in the WT group, 16.3 vs 18.3 months (HR 1.04; 95% CI, 0.79‐1.36) in the SH group, and 13.0 vs 9.1 months (HR 0.71; 95% CI, 0.39‐1.31) in the DHH group, respectively. Modified capecitabine plus irinotecan with or without bevacizumab could be a standard second‐line chemotherapy in terms of efficacy and safety regardless of the UGT1A1 genotype.
Capecitabine plus irinotecan (XELIRI) with or without bevacizumab is noninferior to fluorouracil, leucovorin, and irinotecan (FOLFIRI) with or without bevacizumab in terms of overall survival, regardless of UGT1A1 genotype. Additionally, modified XELIRI with or without bevacizumab showed a favorable tolerability profile that was comparable to that of FOLFIRI with or without bevacizumab among all UGT1A1 genotypes.
Electrical and reliability characteristics of hafnia ferroelectric capacitor are influenced by a capping electrode layer which controls the type of stress and the amount of oxygen vacancy inside ...hafnia. Here, we present the impact of metal nitride and metal oxide electrode on the ferroelectricity of a Hf 0.5 Zr 0.5 O 2 (HZO) capacitor. For comparison, we employed two different top electrodes (RuO 2 and TiN) with hafnia ferroelectric layer, forming RuO 2 /HZO/TiN and TiN/HZO/TiN capacitors. The RuO 2 top electrode provides additional oxygen to the HZO film, lowering the amount of oxygen vacancies in the film. From material analysis, we found that the top RuO 2 /HZO interface exhibits less oxygen vacancy in comparison to the top TiN/HZO interface. In addition, for RuO 2 /HZO/TiN, due to different thermal expansion coefficient between top and bottom electrodes, the HZO film experiences significant tensile stress, resulting in the high o-phase formation and remnant polarization (<inline-formula> <tex-math notation="LaTeX">\sim 20~\mu \text{C} </tex-math></inline-formula>/cm 2 ) as compared with that of TiN/HZO/TiN capacitor (<inline-formula> <tex-math notation="LaTeX">\sim 13~\mu \text{C} </tex-math></inline-formula>/cm 2 ). This article suggests an efficient solution to reduce the interfacial defects and oxygen vacancies as well as to enhance o-phase formation and ferroelectricity.
Oxide thin-film transistors (TFTs) with high mobility that exceed 100 cm2/<inline-formula> <tex-math notation="LaTeX">\text{V}\cdot \text{s} </tex-math></inline-formula> and appropriate turn-on ...voltage (<inline-formula> <tex-math notation="LaTeX">{V}_{\text {on}}{)} </tex-math></inline-formula> are necessary to drive next-generation displays and memory devices. However, a trade-off relationship exists between mobility and <inline-formula> <tex-math notation="LaTeX">{V}_{\text {on}} </tex-math></inline-formula>, making it difficult to achieve both in the same oxide TFT. In this letter, we propose a buffer layer engineered trench-TFT (T-TFT) as a solution to this trade-off problem. Planar-TFT (P-TFT) with an Al2O3 buffer layer exhibits a high current level; however, its <inline-formula> <tex-math notation="LaTeX">{V}_{\text {on}} </tex-math></inline-formula> value is unsuitable. In contrast, P-TFT with an SiO2 buffer demonstrates a <inline-formula> <tex-math notation="LaTeX">{V}_{\text {on}} </tex-math></inline-formula> close to zero, although its mobility remains below 100 cm2/<inline-formula> <tex-math notation="LaTeX">\text{V}\cdot \text{s} </tex-math></inline-formula>. The T-TFT, which incorporates both Al2O3 and SiO2 buffer layers, shows a high mobility of 129 cm2/<inline-formula> <tex-math notation="LaTeX">\text{V}\cdot \text{s} </tex-math></inline-formula> and a suitable <inline-formula> <tex-math notation="LaTeX">{V}_{\text {on}} </tex-math></inline-formula> of −0.4 V, selectively utilizing the advantages of P-TFTs. Based on electrical measurements and material analyses, the active layer on each buffer layer performs a distinct role in the T-TFT; the active layer on SiO2 serves as the "<inline-formula> <tex-math notation="LaTeX">{V}_{\text {on}} </tex-math></inline-formula> determiner," owing to its low oxygen vacancy, whereas the active layer on Al2O3 enhances the mobility, through reduced electron trap sites and a smooth surface.
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