The future transistors.

The metal-oxide-semiconductor field-effect transistor (MOSFET), a core element of complementary metal-oxide-semiconductor (CMOS) technology, represents one of the most momentous inventions since the industrial revolution. Driven by the requirements for higher speed, energy efficiency and integration density of integrated-circuit products, in the past six decades the physical gate length of MOSFETs has been scaled to sub-20 nanometres. However, the downscaling of transistors while keeping the power consumption low is increasingly challenging, even for the state-of-the-art fin field-effect transistors. Here we present a comprehensive assessment of the existing and future CMOS technologies, and discuss the challenges and opportunities for the design of FETs with sub-10-nanometre gate length based on a hierarchical framework established for FET scaling. We focus our evaluation on identifying the most promising sub-10-nanometre-gate-length MOSFETs based on the knowledge derived from previous scaling efforts, as well as the research efforts needed to make the transistors relevant to future logic integrated-circuit products. We also detail our vision of beyond-MOSFET future transistors and potential innovation opportunities. We anticipate that innovations in transistor technologies will continue to have a central role in driving future materials, device physics and topology, heterogeneous vertical and lateral integration, and computing technologies.

Increasing the Energy Gap between Band-Edge and Trap States Slows Down Picosecond Carrier Trapping in Highly Luminescent InP/ZnSe/ZnS Quantum Dots.

Non-toxic InP-based nanocrystals have been developed for promising candidates for commercial optoelectronic applications and they still require further improvement on photophysical properties, compared to Cd-based quantum dots (QDs), for better device efficiency and long-term stability. It is, therefore, essential to understand the precise mechanism of carrier trapping even in the state-of-the-art InP-based QD with near-unity luminescence. Here, it is shown that using time-resolved spectroscopic measurements of systematically size-controlled InP/ZnSe/ZnS core/shell/shell QDs with the quantum yield close to one, carrier trapping decreases with increasing the energy difference between band-edge and trap states, indicating that the process follows the energy gap law, well known in molecular photochemistry for nonradiative internal conversion between two electronic states. Similar to the molecular view of the energy gap law, it is found that the energy gap between the band-edge and trap states is closely associated with ZnSe phonons that assist carrier trapping into defects in highly luminescent InP/ZnSe/ZnS QDs. These findings represent a striking departure from the generally accepted view of carrier trapping mechanism in QDs in the Marcus normal region, providing a step forward understanding how excitons in nanocrystals interact with traps, and offering valuable guidance for making highly efficient and stable InP-based QDs.

Symmetry Dictated Grain Boundary State in a Two-Dimensional Topological Insulator.

Grain boundaries (GBs) are ubiquitous in solids and have been of central importance in understanding the nature of polycrystals. In addition to their classical roles, topological insulators (TIs) offer a chance to realize GBs hosting distinct topological states that can be controlled by their crystal symmetries. However, such roles of crystalline symmetry in two-dimensional (2D) TIs have not been definitively measured yet. Here, we present the first direct evidence of a symmetry-enforced metallic state along a GB in 1T'-MoTe2, a prototypical 2D TI. Using scanning tunneling microscopy, we show a metallic state along a GB with nonsymmorphic lattice symmetry and its absence along another boundary with symmorphic symmetry. Our atomistic simulations demonstrate in-gap Weyl semimetallic states for the former, whereas they demonstrate gapped states for the latter, explaining our observation well. The observed metallic state, tightly linked to its crystal symmetry, can be used to create a stable conducting nanowire inside TIs.

Antioxidant and skin-whitening effects of aerial part of Euphorbia supina Raf. Extract.

BACKGROUND: Euphorbia supina (ES) has been widely used in folk medicine owing to its antibacterial, hemostatic, and anti-inflammatory properties. The aim of this study was to evaluate the antioxidant and skin-whitening effects of a 70% ethanol extract of ES. METHODS: The aerial parts of ES plant were extracted with 70% ethanol. The viability of B16F10 cells was evaluated by MTT assay to determine the non-toxic doses for further experiments. The tyrosinase and cellular tyrosinase activities were then measured using an enzyme-substrate assay. In addition, the expression of whitening-related proteins was measured using western blot. RESULTS: The antioxidant activity of the ES samples increased in a dose-dependent manner, as confirmed by their radical scavenging activities in the 2,2-diphenyl-1-1-picrylhydrazyl and 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) assays. The ES extract significantly reduced tyrosinase activity and melanin content in a dose-dependent manner. Furthermore, it decreased α-melanocyte stimulating hormone (MSH)-induced protein expression of tyrosinase and microphthalmia-associated transcription factor (MITF). CONCLUSIONS: Our results indicate that the ES extract attenuated α-MSH-stimulated melanin synthesis by modulating tyrosinase and MITF expression. Therefore, the ES extract could be a promising therapeutic agent to treat hyperpigmentation and as an ingredient for skin-whitening cosmetics.

Inhibitory effects of Euphorbia supina on Propionibacterium acnes-induced skin inflammation in vitro and in vivo.

BACKGROUND: Euphorbia supina (ES) plant has been used as treatment for inflammatory conditions. The antibacterial effect and the anti-inflammatory mechanism of ES for Propionibacterium (P.) acnes-induced inflammation in THP-1 cells and acne animal model remain unclear. Therefore, the objective of the present study was to determine the antibacterial and anti-inflammatory activities of ES against P. acnes, the etiologic agent of skin inflammation. METHOD: The antibacterial activities of ES were tested with disc diffusion and broth dilution methods. Cytotoxicity of ES at different doses was evaluated by the MTT assay. THP-1 cells were stimulated by heat-killed P. acnes in the presence of ES. The pro-inflammatory cytokines and mRNA levels were measured by ELISA and real-time-PCR. MAPK expression was analyzed by Western blot. The living P. acnes was intradermally injected into the ear of BLBC/c mice. Subsequently, chemical composition of ES was analyzed by liquids chromatography-mass spectrometry (LC-MS). RESULT: ES had stronger antibacterial activity against P. acnes and inhibitory activity on lipase. ES had no significant cytotoxicity on THP-1 cells. ES suppressed the mRNA levels and production of IL-8, TNF-a, IL-1ß in vitro. ES inhibited the expression levels of pro-inflammatory cytokines and the MAPK signaling pathway. Ear thickness and inflammatory cells were markedly reduced by ES treatment. Protocatechuic acid, gallic acid, quercetin, and kaempferol were detected by LC-MS analysis in ES. CONCLUSIONS: Our results demonstrate antibacterial and anti-inflammatory activities of ES extract against P. acnes. It is suggested that ES extract might be used to treatment anti-inflammatory skin disease.

Visible Wavelength Color Filters Using Dielectric Subwavelength Gratings for Backside-Illuminated CMOS Image Sensor Technologies.

We report transmissive color filters based on subwavelength dielectric gratings that can replace conventional dye-based color filters used in backside-illuminated CMOS image sensor (BSI CIS) technologies. The filters are patterned in an 80 nm-thick poly silicon film on a 115 nm-thick SiO2 spacer layer. They are optimized for operating at the primary RGB colors, exhibit peak transmittance of 60-80%, and have an almost insensitive response over a ± 20° angular range. This technology enables shrinking of the pixel sizes down to near a micrometer.

KSHV-encoded viral interferon regulatory factor 4 (vIRF4) interacts with IRF7 and inhibits interferon alpha production.

Before an infection can be completely established, the host immediately turns on the innate immune system through activating the interferon (IFN)-mediated antiviral pathway. Kaposi's sarcoma-associated herpesvirus (KSHV) utilizes a unique antagonistic mechanism of type I IFN-mediated host antiviral immunity by incorporating four viral interferon regulatory factors (vIRF1-4). Herein, we characterized novel immune evasion strategies of vIRF4 to inhibit the IRF7-mediated IFN-α production. KSHV vIRF4 specifically interacts with IRF7, resulting in inhibition of IRF7 dimerization and ultimately suppresses IRF7-mediated activation of type I IFN. These results suggest that each of the KSHV vIRFs, including vIRF4, subvert IFN-mediated anti-viral response via different mechanisms. Therefore, it is indicated that KSHV vIRFs are indeed a crucial immunomodulatory component of their life cycles.

Slim coherent backlight unit for holographic display using full color holographic optical elements.

The coherent backlight unit (BLU) using a holographic optical element (HOE) for full-color flat-panel holographic display is proposed. The HOE BLU consists of two reflection type HOEs that change the optical beam path and shape by diffraction. The illumination area of backlight is 150 mm x 90 mm and the thickness is 10 mm, which is slim compared to other conventional coherent backlight units for holographic display systems. This backlight unit exhibits a total efficiency of 8.0% at red (660 nm), 7.7% at green (532 nm), and 3.2% at blue (460 nm) using optimized recording conditions for each wavelength. As a result, we could get a bright full color hologram image.

Anti-inflammatory effect of Euphorbia supina extract in dextran sulfate sodium-induced colitis mice.

The aim of this study is to examine the anti-inflammatory effect of Euphorbia supina (ES) ethanol extract in dextran sulfate sodium (DSS)-induced experimental colitis model. ES was per orally administered at different doses of 4 or 20 mg/kg body weight with 5% DSS in drinking water for 7 days. Twenty mg/kg of ES administration regulated body weight decrease, recovered colon length shortening, and increased disease activity index score and myeloperoxidase level in DSS-induced colitis. Histological features showed that 20 mg/kg of ES administration suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Furthermore, ES suppressed the expressions of COX-2, iNOS, NF-kB, IkBα, pIkBα in colon tissue. These findings demonstrated a possible effect of amelioration of ulcerative colitis and could be clinically applied.

Reconfigurable van der Waals Heterostructured Devices with Metal-Insulator Transition.

Atomically thin two-dimensional (2D) materials range from semimetallic graphene to insulating hexagonal boron nitride to semiconducting transition-metal dichalcogenides. Recently, metal-insulator-semiconductor field effect transistors built from these 2D elements were studied for flexible and transparent electronics. However, to induce ambipolar characteristics for alternative power-efficient circuitry, ion-gel gating is often employed for high capacitive coupling, limiting stable operation at ambient conditions. Here, we report reconfigurable MoTe2 optoelectronic transistors with all 2D components, where the device can be reconfigured by both drain and gate voltages. Eight different configurations for each fixed voltage are spatially resolved by scanning photocurrent microscopy. In addition, metal-insulator transitions are observed in both electron and hole carriers under 2 V due to strong Coulomb interaction in the system. Furthermore, the vertical tunneling photocurrent through multiple van der Waals layers between the gate and source contacts is measured. Our reconfigurable devices offer potential building blocks for system-on-a-chip optoelectronics.

Selective exfoliation of single-layer graphene from non-uniform graphene grown on Cu.

Graphene growth on a copper surface via metal-catalyzed chemical vapor deposition has several advantages in terms of providing high-quality graphene with the potential for scale-up, but the product is usually inhomogeneous due to the inability to control the graphene layer growth. The non-uniform regions strongly affect the reliability of the graphene in practical electronic applications. Herein, we report a novel graphene transfer method that allows for the selective exfoliation of single-layer graphene from non-uniform graphene grown on a Cu foil. Differences in the interlayer bonding energy are exploited to mechanically separate only the top single-layer graphene and transfer this to an arbitrary substrate. The dry-transferred single-layer grapheme showed electrical characteristics that were more uniform than those of graphene transferred using conventional wet-etching transfer steps.

Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

Graphene and thin-film semiconductor heterojunction transistors integrated on wafer scale for low-power electronics.

Graphene heterostructures in which graphene is combined with semiconductors or other layered 2D materials are of considerable interest, as a new class of electronic devices has been realized. Here we propose a technology platform based on graphene-thin-film-semiconductor-metal (GSM) junctions, which can be applied to large-scale and power-efficient electronics compatible with a variety of substrates. We demonstrate wafer-scale integration of vertical field-effect transistors (VFETs) based on graphene-In-Ga-Zn-O (IGZO)-metal asymmetric junctions on a transparent 150 × 150 mm(2) glass. In this system, a triangular energy barrier between the graphene and metal is designed by selecting a metal with a proper work function. We obtain a maximum current on/off ratio (Ion/Ioff) up to 10(6) with an average of 3010 over 2000 devices under ambient conditions. For low-power logic applications, an inverter that combines complementary n-type (IGZO) and p-type (Ge) devices is demonstrated to operate at a bias of only 0.5 V.

The effect of trapped charge on silicon nanowire pseudo-MOSFETs.

The effects of organic molecules grafted on top of silicon nanowires are modeled as the oxide trap charges (Qot) and interface trap charges (Qit). The device investigated here is a pseudo-MOSFET with a thick bottom oxide (200 nm) and only a thin native oxide (5 nm) on top. With Qot = -5.0 x 10(11) cm(-2) and the U-shaped distribution of interface trap density (Dit) as a function of trap energy (Et), the structures are reproduced through the conventional technology computer aided design (TCAD) simulation tool, and the channel is imaginarily divided into several sections (5 x 5 regions) to apply the localized traps. The electrical parameters are extracted from the each part to quantitatively compare their effectiveness. The local position of the grafted molecules, modeled by these charges, is shown to result in strong variations in the relative change in the threshold voltage and subthreshold swing. These variations are explained by the surface depletion and scattering near the edges of the etched device and the series resistance effect.

The effects of maternal-child nursing clinical practicum using virtual reality on nursing students' competencies: a systematic review.

PURPOSE: This study aimed to investigate the effects of virtual reality used in maternal-child nursing clinical practicums on nursing students' competencies through a systematic review. METHODS: The inclusion criteria were peer-reviewed papers in English or Korean presenting analytic studies of maternal-child nursing practicums using virtual reality. An electronic literature search of the Cochrane Library, CINAHL, EMBASE, ERIC, PubMed, and Research Information Sharing System databases was performed using combinations of the keywords "nursing student," "virtual reality," "augmented reality," "mixed reality," and "virtual simulation" from February 4 to 15, 2022. Quality appraisal was performed using the RoB 2 and ROBINS-I tools for randomized controlled trials (RCTs) and non-RCTs, respectively. RESULTS: Of the seven articles identified, the RCT study (n=1) was deemed to have a high risk of bias, with some items indeterminable due to a lack of reported details. Most of the non-RCT studies (n=6) had a moderate or serious risk of bias related to selection and measurement issues. Clinical education using virtual reality had positive effects on knowledge, skills, satisfaction, self-efficacy, and needs improvement; however, it did not affect critical thinking or self-directed learning. CONCLUSION: This study demonstrated that using virtual reality for maternal-child nursing clinical practicums had educational effects on a variety of students' competencies. Considering the challenges of providing direct care in clinical practicums, virtual reality can be a viable tool that supplements maternal-child nursing experience. Greater rigor and fuller reporting of study details are required for future research.

Actuating compact wearable augmented reality devices by multifunctional artificial muscle.

An artificial muscle actuator resolves practical engineering problems in compact wearable devices, which are limited to conventional actuators such as electromagnetic actuators. Abstracting the fundamental advantages of an artificial muscle actuator provides a small-scale, high-power actuating system with a sensing capability for developing varifocal augmented reality glasses and naturally fit haptic gloves. Here, we design a shape memory alloy-based lightweight and high-power artificial muscle actuator, the so-called compliant amplified shape memory alloy actuator. Despite its light weight (0.22 g), the actuator has a high power density of 1.7 kW/kg, an actuation strain of 300% under 80 g of external payload. We show how the actuator enables image depth control and an immersive tactile response in the form of augmented reality glasses and two-way communication haptic gloves whose thin form factor and high power density can hardly be achieved by conventional actuators.

Fabrication of nanometer-scale carbon nanotube field-effect transistors on flexible and transparent substrate.

We have successfully fabricated nanometer-scale carbon nanotube field effect transistors (CNT FETs) on a flexible and transparent substrate by electron-beam lithography. The measured current-voltage data show good hole conduction FET characteristics, and the on/off ratio of the current is more than 10(2). The conductance (as well as current) systematically decreases with the increase of the strain, suggesting that the bending of the substrate still affects the deformation condition of the short channel CNT FETs.

Silver Nanowire Network Hybridized with Silver Nanoparticle-Anchored Ruthenium Oxide Nanosheets for Foldable Transparent Conductive Electrodes.

Facile strategies in flexible transparent conductive electrode materials that can sustain their electrical conductivities under 1 mm-scale radius of curvature are required for wider applications such as foldable devices. We propose a rational design as well as a fabrication process for a silver nanowire-based transparent conductive electrode with low sheet resistance and high transmittance even after prolonged cyclic bending. The electrode is fabricated on a poly(ethylene terephthalate) film through the hybridization of silver nanowires with silver nanoparticles-anchored RuO2 nanosheets. This hybridization significantly improves the performance of the silver nanowire network under severe bending strain and creates an electrically percolative structure between silver nanowires and RuO2 nanosheets in the presence of anchored silver nanoparticles on the surface of RuO2 nanosheets. The resistance change of this hybrid transparent conductive electrode is 8.8% after 200,000 bending cycles at a curvature radius of 1 mm, making it feasible for use in foldable devices.

All-solid-state spatial light modulator with independent phase and amplitude control for three-dimensional LiDAR applications.

Spatial light modulators are essential optical elements in applications that require the ability to regulate the amplitude, phase and polarization of light, such as digital holography, optical communications and biomedical imaging. With the push towards miniaturization of optical components, static metasurfaces are used as competent alternatives. These evolved to active metasurfaces in which light-wavefront manipulation can be done in a time-dependent fashion. The active metasurfaces reported so far, however, still show incomplete phase modulation (below 360°). Here we present an all-solid-state, electrically tunable and reflective metasurface array that can generate a specific phase or a continuous sweep between 0 and 360° at an estimated rate of 5.4 MHz while independently adjusting the amplitude. The metasurface features 550 individually addressable nanoresonators in a 250 × 250 µm2 area with no micromechanical elements or liquid crystals. A key feature of our design is the presence of two independent control parameters (top and bottom gate voltages) in each nanoresonator, which are used to adjust the real and imaginary parts of the reflection coefficient independently. To demonstrate this array's use in light detection and ranging, we performed a three-dimensional depth scan of an emulated street scene that consisted of a model car and a human figure up to a distance of 4.7 m.