Mobility and Current Boosting of In-Ga-Zn-O thin-film transistors with Metal Capping Layer Oxidation.

This study investigates the effect of an oxidized Ta capping layer on the boosting of field-effect mobility (µFE) of amorphous In-Ga-Zn-O (a-IGZO) Thin-film transistors (TFTs). The oxidation of Ta creates additional oxygen vacancies on the a-IGZO channel surface, leading to increased carrier density. We investigate the effect of increasing Ta coverage on threshold voltage (Vth), on-state current, µFE and gate bias stress stability of a-IGZO TFTs. A significant increase in µFE of over 8 fold, from 16 cm²/Vs to 140 cm²/Vs, was demonstrated with the Ta capping layer covering 90 % of the channel surface. By partial leaving the a-IGZO uncovered at the contact region, a potential barrier region was created, maintaining the low off-state current and keeping the threshold voltage near 0 V, while the capped region operated as a carrier-boosted region, enhancing channel conduction. The results reported in this study present a novel methodology for realizing high-performance oxide semiconductor devices. The demonstrated approach holds promise for a wide range of next-generation device applications, offering new avenues for advancement in metal oxide semiconductor TFTs. .

Improved high voltage operation of amorphous In-Ga-Zn-O thin film transistor by carrier density enhancement.

We report on improved high voltage operation of amorphous-In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) by increasing carrier density and distributing the high bias field over the length of the device which utilizes an off-set drain structure. By decreasing the O2partial pressure during sputter deposition of IGZO, the channel carrier density of the high voltage a-IGZO TFT (HiVIT) was increased to ∼1018cm-3. Which reduced channel resistance and therefore the voltage drop in the ungated offset region during the on-state. To further decrease the electric field in the offset region, we applied Ta capping and subsequent oxidation to locally increase the oxygen vacancy levels in the offset region thereby increasing local carrier density. The reduction of the drain field in the offset region from 1.90 Vµm-1to 1.46 Vµm-1at 200 V drain voltage, significantly improved the operational stability of the device by reducing high field degradation. At an extreme drain voltage of 500 V, the device showed an off-state current of ∼10-11A and on-state current of ∼1.59 mA demonstrating that with further enhancements the HiVIT may be applicable to thin-film form, low leakage, high voltage control applications.

The association between the restriction of daily life and depression during the COVID-19 pandemic in Korea: a nationwide based survey.

The coronavirus (COVID-19) pandemic has led to substantial daily life changes for people worldwide. We investigated the association between daily life restrictions and depression during the COVID-19 pandemic based on the Korea Community Health Survey. Daily life restrictions were evaluated using a questionnaire to population into three restriction categories: no/slightly, moderately, and severely. Depression was assessed by the Korean version of the Patient Health Questionnaire-9 (PHQ-9). Chi-square tests and Fisher's exact tests were used to compare the demographic characteristics of individuals with and without depression. Logistic regression was used to assess the association between the severity of daily life restrictions and the prevalence of depression. The prevalence of depression was 2.4% in the total population: 5.7% in the severely restricted group and 2.7% in the moderately restricted group. After adjusting for age, sex, educational level, income, marital status, and employment status, the severely restricted group was more likely to have depression than was the no change/slightly restricted group (OR = 2.40, 95% CI 2.16-2.67, p < 0.001). Employers with severely restricted daily life exhibited a higher OR for depression compared to the no/slightly restricted group (OR = 3.24, 95% CI 2.37-4.45, p < 0.001). It is necessary to consider the mental health of vulnerable affected by the COVID-19 pandemic.

Microelectronic current-sourcing device based on band-to-band tunneling current.

A new stable current-sourcing transistor is developed using the band-to-band tunneling phenomenon. A heterojunction between thin film WS2and heavily hole-doped bulk silicon converts a section of the WS2contacting the silicon into a hole-doped WS2inside the WS2channel, and band-to-band tunneling occurs between the electron-doped and hole-doped WS2. The output current is regulated by the tunneling barrier thickness. The thickness depends on the gate bias for device switching, but is less sensitive to the source bias, enabling stable output currents. The minimum line sensitivity is 2.6%, and the temperature coefficient is 1.4 × 103ppm°C-1. The device can be operated as a current sourcing device with an ultralow output current and power consumption.

An Ultralow Power Mixed Dimensional Heterojunction Transistor Based on the Charge Plasma pn Junction.

Development of a reliable doping method for 2D materials is a key issue to adopt the materials in the future microelectronic circuits and to replace the silicon, keeping the Moore's law toward the sub-10 nm channel length. Especially hole doping is highly required, because most of the transition metal dichalcogenides (TMDC) among the 2D materials are electron-doped by sulfur vacancies in their atomic structures. Here, hole doping of a TMDC, tungsten disulfide (WS2 ) using the silicon substrate as the dopant medium is demonstrated. An ultralow-power current sourcing transistor or a gated WS2 pn diode is fabricated based on a charge plasma pn heterojunction formed between the WS2 thin-film and heavily doped bulk silicon. An ultralow switchable output current down to 0.01 nA µm-1 , an off-state current of ≈1 × 10-14 A µm-1 , a static power consumption range of 1 fW µm-1 -1 pW µm-1 , and an output current ratio of 103 at 0.1 V supply voltage are achieved. The charge plasma heterojunction allows a stable (less than 3% variation) output current regardless of the gate voltage once it is turned on.

Trends in Nursing Research on Life-Sustaining Treatment in South Korea after the Enforcement of the Act on Decisions on Life-Sustaining Treatment.

Purpose: This study investigated trends of nursing research on life-sustaining treatment in South Korea. Methods: The period for data search was set from January 2018 to December 2020. The major search terms used were advance directives and life-sustaining treatment. Of the 492 records identified in the initial search, 461 articles were excluded for various reasons. A total of 31 records were included in the final qualitative analysis. Results: Sixteen studies had nursing students as study subjects, while nine studies had nurses as study subjects. The majority of the studies employed cross-sectional descriptive surveys as their research design. The major themes that emerged from the studies were as follows attitudes toward withdrawal of life-sustaining treatment, knowledge of and attitudes toward advance directives, perceptions of a good death, and nurses' attitude toward life support care. Most of the studies reviewed concluded that attitudes toward withdrawal of life-sustaining treatment significantly impacted both knowledge of and attitudes toward advance directives and perceptions of a good death. Conclusion: To date, Korea still lacks extensive nursing research concerning life support care. Further research is needed to provide systematic education for nursing ethics and life support care, as well as the introduction of a specialist course. Furthermore, a multidisciplinary approach is necessary to provide diverse support systems and policy measures. In particular, since nurses are directly responsible for providing life support care, nurses' roles should be expanded in accordance with the Act on Decisions on Life-Sustaining Treatment.

Tactile Interaction Sensor with Millimeter Sensing Acuity.

In this article we report on a 3 × 3 mm tactile interaction sensor that is able to simultaneously detect pressure level, pressure distribution, and shear force direction. The sensor consists of multiple mechanical switches under a conducting diaphragm. An external stimulus is measured by the deflection of the diaphragm and the arrangement of mechanical switches, resulting in low noise, high reliability, and high uniformity. Our sensor is able to detect tactile forces as small as ~50 mgf along with the direction of the shear force. It also distinguishes whether there is a normal pressure during slip motion. We also succeed in detecting the contact shape and the contact motion, demonstrating potential applications in robotics and remote input interfaces. Since our sensor has a simple structure and its function depends only on sensor dimensions, not on an active sensing material, in comparison with previous tactile sensors, our sensor shows high uniformity and reliability for an array-type integration.

Integrated pharmaco-proteogenomics defines two subgroups in isocitrate dehydrogenase wild-type glioblastoma with prognostic and therapeutic opportunities.

The prognostic and therapeutic relevance of molecular subtypes for the most aggressive isocitrate dehydrogenase 1/2 (IDH) wild-type glioblastoma (GBM) is currently limited due to high molecular heterogeneity of the tumors that impedes patient stratification. Here, we describe a distinct binary classification of IDH wild-type GBM tumors derived from a quantitative proteomic analysis of 39 IDH wild-type GBMs as well as IDH mutant and low-grade glioma controls. Specifically, GBM proteomic cluster 1 (GPC1) tumors exhibit Warburg-like features, neural stem-cell markers, immune checkpoint ligands, and a poor prognostic biomarker, FKBP prolyl isomerase 9 (FKBP9). Meanwhile, GPC2 tumors show elevated oxidative phosphorylation-related proteins, differentiated oligodendrocyte and astrocyte markers, and a favorable prognostic biomarker, phosphoglycerate dehydrogenase (PHGDH). Integrating these proteomic features with the pharmacological profiles of matched patient-derived cells (PDCs) reveals that the mTORC1/2 dual inhibitor AZD2014 is cytotoxic to the poor prognostic PDCs. Our analyses will guide GBM prognosis and precision treatment strategies.

Racial/ethnic differences in correlates of psychological distress among five Asian-American subgroups and non-Hispanic Whites.

Objective: Despite their vastly different historical backgrounds, unique languages and variable pre- and post-immigration experiences, Asian-Americans are considered to share stressors surrounding immigration, but there is a gap in describing manifestations of possible mental distress. Thus, the purpose of this study was to explore and compare differences in factors associated with psychological distress among Asian subgroups including Chinese, Filipino, Vietnamese, Korean, Japanese, and non-Hispanic Whites. Design: Using a cross-sectional study design, California Health Interview Survey (CHIS) 2011/2012 data were analyzed. The sample consisted of 29,142 participants: 25,645 non-Hispanic Whites, 3497 non-Hispanic Asian-Americans, 1156 Chinese, 471 Filipinos, 864 Vietnamese, 704 Koreans, and 302 Japanese. Sociodemographic characteristics included gender, age group, marital status, education, poverty level, working status, health insurance, level of acculturation, social cohesion, neighborhood safety, and civic engagement. Physical health status included disability and chronic illness. Psychological distress was evaluated using the Kessler 6 (K6) scale. Results: Results showed that psychological distress levels ranged between 1.96 and 4.52 (p < .05) out of 24 and associated factors were significantly different among the five Asian subgroups and non-Hispanic Whites. Conclusions: The current study highlights the differences in characteristics of psychological distress among Asian subgroups. It underscores the significance of understanding individualized cultural and historical background in each Asian subgroup and subsequently developing and applying appropriate interventions for those groups. In addition, different influencing factors should be applied to assess and prioritize the needs of Asian subgroups to improve psychological distress. The study also warrants further investigation and careful description of each Asian subgroups.

Biomimetic Tactile Sensors with Bilayer Fingerprint Ridges Demonstrating Texture Recognition.

In this article, we report on a biomimetic tactile sensor that has a surface kinetic interface (SKIN) that imitates human epidermal fingerprint ridges and the epidermis. The SKIN is composed of a bilayer polymer structure with different elastic moduli. We improved the tactile sensitivity of the SKIN by using a hard epidermal fingerprint ridge and a soft epidermal board. We also evaluated the effectiveness of the SKIN layer in shear transfer characteristics while varying the elasticity and geometrical factors of the epidermal fingerprint ridges and the epidermal board. The biomimetic tactile sensor with the SKIN layer showed a detection capability for surface structures under 100 µm with only 20-µm height differences. Our sensor could distinguish various textures that can be easily accessed in everyday life, demonstrating that the sensor may be used for texture recognition in future artificial and robotic fingers.

Graphene surface contacts of tin disulfide transistors for switching performance improvement and contact resistance reduction.

We investigated the performance improvement of tin disulfide channel transistors by graphene contact configurations. From its two-dimensional nature, graphene can make electric contacts only at the outermost layers of the channel. For intralayer current flow, two graphene flakes are contacted at the channel's top or bottom layer. For interlayer current flow, one flake is contacted at the top and bottom of each layer. We compared the transistor performance in terms of current magnitude, mobility, and subthreshold swing between the configurations. From such observations, we deduced that device characteristics depend on resistivity or doping level of individual graphene flakes. We also found that interlayer flow excels in the on-current magnitude and the mobility, and that top-contact configuration excels in the subthreshold swing.

The effect of compositional engineering of imidazolium lead iodide on the resistive switching properties.

We report here resistive switching memory characteristics of imidazolium lead iodide depending on the molar ratio of PbI2 to imidazolium iodide (ImI), that is, PbI2 : ImI = 1 : 0, 1 : 0.5, 1 : 1, 1 : 2, 1 : 3 and 0 : 1. X-ray diffraction confirms that the stoichiometric composition results in a hexagonal structure of (Im)PbI3, showing a one-dimensional face-sharing [PbI3-] chain. Bipolar resistive switching characteristics are observed regardless of the mixing ratio, where the forming process is required prior to SET and RESET processes at around +0.2 V and -0.2 V, respectively. The ON/OFF ratio is increased from 106 to 109 as the ImI content is increased due to the increased HRS associated with the pronounced insulating characteristics by ImI, whereas, the stoichiometric (Im)PbI3 exhibits 5 times longer endurance (103) and an order of magnitude longer retention time (104 s) as compared to other compositions. Multilevel data storage capability is confirmed by changing the compliance current. The low resistance state (LRS) and the high resistance state (HRS) are associated with Ohmic conduction and Schottky conduction, respectively. Density functional theory (DFT) calculation reveals that the defect formation energy of iodine vacancy is estimated to be low indicating that (Im)PbI3 has a sufficient concentration of iodide vacancy for filament formation. Further energy barrier calculations show that iodide migration preferentially occurs along the 1-dimensional [234] crystallographic direction rather than the interlayer [130] direction. A good performance of the (Im)PbI3-based memristor is thus related to the low defect formation energy of iodide vacancy and the preferential growth of the filament along the 1-dimensional chain.

Effect of interlayer spacing in layered perovskites on resistive switching memory.

We report here the effect of interlayer spacing in 2-dimensional (2D) perovskites of [C6H5(CH2)nNH3]2PbI4 (anilinium (An) for n = 0, benzylammonium (BzA) for n = 1 and phenylethylammonium (PEA) for n = 2) on resistive switching properties. X-ray diffraction (XRD) reveals that the interlayer spacing of layered PbI2 is increased from 6.98 Å to 13.29 Å for (An)2PbI4, 14.20 Å for (BzA)2PbI4 and 15.92 Å for (PEA)2PbI4, which leads to a monolayer of organic cations with stacked benzene rings between inorganic PbI42- layers. All the samples in the device structure of Ag/PMMA (polymethyl methacrylate)/perovskite/Pt show bipolar switching behavior, where the SET voltage is near +0.2 V and the RESET voltage is less than -0.5 V. The ratio of LRS (low resistance state) to HRS (high resistance state), also called the ON/OFF ratio, is increased from 106 to 108 as interlayer spacing is increased due to the gradual increase in resistance in the HRS. Endurance is slightly improved from 1.3 × 102 for An to 2.2 × 102 for PEA, whereas substantial improvement in retention is observed from 2 × 103 to 5.5 × 103. This indicates that the enhanced 2D structure is beneficial to the kinetics of forming and rupturing the conducting filaments. The ohmic-like conduction mechanism in the LRS and the hopping mechanism in the HRS are observed for all three samples. This work finds that the resistive switching properties and conduction mechanism in the HRS depend on interlayer spacing in 2D perovskites.

Highly Sensitive Tactile Shear Sensor Using Spatially Digitized Contact Electrodes.

In this article, we report on a highly sensitive tactile shear sensor that was able to detect minute levels of shear and surface slip. The sensor consists of a suspended elastomer diaphragm with a top ridge structure, a graphene layer underneath, and a bottom substrate with multiple spatially digitized contact electrodes. When shear is applied to the top ridge structure, it creates torque and deflects the elastomer downwards. Then, the graphene electrode makes contact with the bottom spatially digitized electrodes completing a circuit producing output currents depending on the number of electrodes making contact. The tactile shear sensor was able to detect shear forces as small as 6 µN, detect shear direction, and also distinguish surface friction and roughness differences of shearing objects. We also succeeded in detecting the contact slip motion of a single thread demonstrating possible applications in future robotic fingers and remote surgical tools.

Buckled carbon nanotube network thin-film fabricated using chemically swelled elastomer substrates.

We report on the fabrication of buckled carbon nanotube thin-film networks (CNTN) that increases in conductivity with applied tactile pressure. When tactile pressure was applied, the buckled nanotubes collapsed and increased in interconnected density and as a result increased the thin-film conductivity. Unlike conventional methods using mechanically expanded elastomers, we utilize chemically swollen elastomers as the expanded substrate to transfer the CNTN. As the chemical evaporates, it compresses the CNTN causing the thin-film to buckle. The CNTN compression can be controlled by using organic solvents with differing elastomer absorption rates. Our method requires no mechanical instruments and shows in-plane multi-axial uniform strain for the entire substrate surface. Since the buckling was controlled chemically, the buckled CNTN can be produced reliably, furthering the possibility of its application as the active sensing material for highly sensitive tactile pressure sensors.

Perovskite-related (CH3NH3)3Sb2Br9 for forming-free memristor and low-energy-consuming neuromorphic computing.

Organic-inorganic halide perovskite materials exhibit excellent memristive properties, such as a high on/off ratio and low switching voltage. However, most studies have focused on Pb-based perovskites. Here, we report on the resistive switching and neuromorphic computing properties of Pb-free perovskite-related MA3Sb2Br9 (MA = CH3NH3). The Ag/PMMA/MA3Sb2Br9/ITO devices show forming-free characteristics due to a self-formed conducting filament induced by metallic Sb present in the as-prepared MA3Sb2Br9 layer. An MA3Sb2Br9-based memristor exhibits a reliable on/off ratio (∼102), an endurance of 300 cycles, a retention time of ∼104 s and multilevel storage characteristics. Furthermore, synaptic characteristics, such as short-term potentiation, short-term depression and long-term potentiation, are revealed along with a low energy-consumption of 117.9 fJ µm-2, which indicates that MA3Sb2Br9 is a promising material for neuromorphic computing.

Racial and Ethnic Differences in Mental Health among Asian Americans and Non-Hispanic Whites: Based on California Health Interview Survey.

While Asians are becoming the largest ethnic group in the United States, studies have focused on Asians as a single population. The purpose of this study was to explore the racial and ethnic mental health differences between non-Hispanic Whites and Asians, with an emphasis on understudied subgroups, from the California Health Interview Survey 2011/2012. In this dataset Asians had significantly lower adjusted odds ratios for both mental distress and serious mental illness. However, when Asians were divided into subgroups and compared to Whites, Vietnamese and Japanese subgroups were significantly lower than Whites for mental distress while Koreans were significantly higher. Vietnamese and Chinese were found to have significantly less serious mental illness than Whites in the subgroup analyses. Our results underscore the importance of recognizing that Asian subgroups should not be overlooked, and all Asians should not automatically be treated as a homogenous group.

The association between work-life balance and health status among Korean workers.

BACKGROUND: Although the relationship between work-life balance (WLB) and health is well known, it has been poorly studied in Korea. OBJECTIVE: This study investigated factors related to WLB for Korean workers, including working time features and the relationships between WLB and health outcomes. METHODS: Data were obtained from the third Korean Working Conditions Survey, which examined a representative working population. This study investigated general characteristics, working time characteristics, work related health, and WLB. A multivariate logistic regression was used to test the associations between WLB and health outcome variables, including general health status, mental health, work-related risks to health and safety, sickness absenteeism, presenteeism, musculoskeletal disease, headache/eyestrain, and fatigue. RESULTS: General characteristics including gender, age, working sector, occupation, and employment type were found to be related to WLB. Moreover, working time characteristics were found to be strongly related to WLB. In addition, WLB was significantly related to various health outcomes. CONCLUSIONS: Our findings indicate that WLB is strongly related to health outcomes among Korean workers. The results suggest that there is a need for interventions that focus on implementing working time strategies for better health.

Health Inequalities Among Korean Employees.

BACKGROUND: Social status might be a determinant of occupational health inequalities. This study analyzed the effects of social status on both work environments and health outcomes. METHODS: The study sample consisted of 27,598 wage employees aged 15 years and older from among the Korean Working Condition Survey participants in 2011. Work environments included atypical work, physical risks, ergonomic risks, work demands, work autonomy, social supports, and job rewards. Health outcomes comprised general health, health and safety at risk because of work, the World Health Organization-5 Well-being Index, work-related musculoskeletal disease, and work-related injury. Multivariable logistic-regression models were used to identify the associations between social status and work environments and health outcomes. RESULTS: Employees in the demographically vulnerable group had lower occupational status compared with their counterparts. Low social status was largely related to adverse work environments. Especially, precarious employment and manual labor occupation were associated with both adverse work environments and poor health outcomes. CONCLUSION: Precarious and manual workers should take precedence in occupational health equity policies and interventions. Their cumulative vulnerability, which is connected to demographics, occupational status, adverse work environments, or poor health outcomes, can be improved through a multilevel approach such as labor market, organizations, and individual goals.

A Portable Stiffness Measurement System.

A new stiffness measurement method is proposed that utilizes the lateral deformation profile of an object under indentation. The system consists of a force measurement module between a pair of equidistant touch sensing modules. Unique feature of the method is that by adjusting the touch module separation, indenter protrusion, and spring constant of the force sensing module, one can choose a desired sensing range for the force module. This feature helps to enhance the stiffness differentiation between objects of similar hardness and avoids measurement saturation. We devised a portable measurement system based on the method, and tested its performance with several materials including polymer foams and human skin.