Silicon germanium photo-blocking layers for a-IGZO based industrial display

Amorphous indium- gallium-zinc oxide (a-IGZO) has been intensively studied for the application to active matrix flat-panel display because of its superior electrical and optical properties. However, the characteristics of a-IGZO were found to be very sensitive to external circumstance such as light illumination, which dramatically degrades the device performance and stability practically required for display applications. Here, we suggest the use for silicon-germanium (Si-Ge) films grown plasmaenhanced chemical vapour deposition (PECVD) as photo-blocking layers in the a-IGZO thin film transistors (TFTs). The charge mobility and threshold voltage (V-th) of the TFTs depend on the thickness of the Si-Ge films and dielectric buffer layers (SiNX), which were carefully optimized to be similar to 200 nm and similar to 300 nm, respectively. As a result, even after 1,000 s illumination time, the V-th and electron mobility of the TFTs remain unchanged, which was enabled by the photo-blocking effect of the Si-Ge layers for a-IGZO films. Considering the simple fabrication process by PECVD with outstanding scalability, we expect that this method can be widely applied to TFT devices that are sensitive to light illumination.

Sustained Benefit of Alternate Behavioral Interventions to Improve Hypertension Control: A Randomized Clinical Trial

Little is known about the long-term effects of behavioral interventions to improve blood pressure (BP) control. We evaluated whether a telephone-delivered, behavioral stage-matched intervention (SMI), or a nontailored health education intervention (HEI) delivered for 6 months improves BP control (or lowers systolic BP) over 12 months, as well as its sustainability 6 months after intervention implementation ended, compared with usual care in participants with repeated uncontrolled BP at baseline. A 3-arm, randomized controlled trial was designed to evaluate the effectiveness of 2 interventions, each compared with a usual-care control group. Participants were 533 adults with persistent uncontrolled BP who were treated at 2 Veterans Affairs Medical Centers. The intervention was implemented for 6 months, followed by 6 months of observation. Compared with usual care, the odds of having BP under control over 12 months in SMI were 84% higher (odds ratio, 1.84 [95% CI, 1.28–2.67]; P=0.001), and 48% higher in HEI (odds ratio, 1.48 [95% CI, 1.02–2.14]; P=0.04).Over the 12 months, compared with usual care, systolic blood pressure was 2.80 mm Hg lower in SMI ([95% CI, 0.27 to 5.33]; P=0.03) while it was 2.58 mm Hg lower in HEI ([95% CI, −0.40 to 5.55]; P=0.09). From 6 to 12 months, SMI sustained improved BP control and lower systolic blood pressure, while HEI, which did not have significantly better BP control or lower systolic blood pressure at 6 months, appeared to improve BP control and lower systolic blood pressure. SMI and HEI are promising interventions that can be implemented in clinical practice to improve BP management

Threshold Voltage Drift in Te-Based Ovonic Threshold Switch Devices Under Various Operation Conditions

In this research, we investigate threshold voltage drift in a B-Te based OTS device under various operation conditions. To this aim, drift of threshold voltage after a switching process is examined. From the measurements, we find that the threshold voltage required to switch the device back after the first switching process decreases when the interval between the voltage pulsespplied for the switching is shorter than 10 mu s, and becomes drift-free afterward. This result implies that a certain amount of heat is generated during the first switch which results in higher local temperature that lowers the threshold voltage, and is dissipated completely after 10 mu s. A 3D finite element simulation is provided to demonstrate the thermal effect induced by the switching pulse. Our results demonstrate that the threshold voltage of the Te-based OTS device is affected by thermal effects during switching at short time scales, and thus indicate that the threshold voltage drift should be considered carefully in the fast device operation.11Nsciescopu

Large-scale transfer-free growth of thin graphite films at low temperature for solid diffusion barriers

Amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) have been under intense investigation as one of the promising candidates for active matrix flat-panel displays. However, solid diffusion of a-IGZO to other layers during TFT device fabrication highly degrades their electrical and optical properties. It is expected that the diffusion-impenetrable properties of graphitic materials can be utilized as diffusion barriers. A conventional transfer method and direct growth on TFTs with high temperature are limited due to wet transfer conditions and low T-g (similar to 540 degrees C) of the glass substrates, respectively. Here we report the large-scale transfer-free growth of thin graphite films at low temperature (similar to 350 degrees C) for solid diffusion barriers in the a-IGZO TFTs using plasma enhanced chemical vapor deposition (PECVD), which can be widely used to protect solid-diffusion for sustainable and scalable future industrial technology

High-Output and Bending-Tolerant Triboelectric Nanogenerator Based on an Interlocked Array of Surface-Functionalized Indium Tin Oxide Nanohelixes

We present a high-performance flexible tribo-electric nanogenerator (TENG) based on an interlocked array of surface-functionalized indium tin oxide (ITO) nanohelix (NH) structures. The structural properties of ITO NHs, including a high nanoscale roughness and unique spring-like geometry, provide a large surface area for an effective friction, enhanced tolerance to bending strain, and operational reliability. The TENG device with surface-functionalized ITO NHs exhibits a significantly enhanced (over 340 times) electrical output power compared to the TENG based on plane ITO. This is attributed to the effective generation of static charges on the large functionalized surface area as well as the efficient charge induction in the ITO electrodes with a unique geometry. We believe that our approach simultaneously overcomes the limitations of available dielectric materials and their low conductivity and reliability and thus can pave the way for the development of portable and wearable self-powered electronic devices.11Nsciescopu

A soft pressure sensor array based on a conducting nanomembrane

© 2021 by the authors. Licensee MDPI, Basel, Switzerland.Although skin-like pressure sensors exhibit high sensitivity with a high performance over a wide area, they have limitations owing to the critical issue of being linear only in a narrow strain range. Various strategies have been proposed to improve the performance of soft pressure sensors, but such a nonlinearity issue still exists and the sensors are only effective within a very narrow strain range. Herein, we fabricated a highly sensitive multi-channel pressure sensor array by using a simple thermal evaporation process of conducting nanomembranes onto a stretchable substrate. A rigid-island structure capable of dissipating accumulated strain energy induced by external mechanical stimuli was adopted for the sensor. The performance of the sensor was precisely controlled by optimizing the thickness of the stretchable substrate and the number of serpentines of an Au membrane. The fabricated sensor exhibited a sensitivity of 0.675 kPa−1 in the broad pressure range of 2.3–50 kPa with linearity (~0.990), and good stability (>300 Cycles). Finally, we successfully demonstrated a mapping of pressure distribution.11Nsciescopu

Tunable Two-Channel Magnetotransport in SrRuO3 Ultrathin Films Achieved by Controlling the Kinetics of Heterostructure Deposition

© 2021 Wiley-VCH GmbHIn the field of oxide heterostructure engineering, there are extensive efforts to couple the various functionalities of each material. The Berry curvature-driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to the electronic structures near the Fermi surface driven by extensive physical parameters such as spin–orbit coupling and inversion symmetry breaking. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies.” Here, a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers is developed. The kinetic process of pulsed laser deposition by varying the growth pressure during LaAlO3 layer deposition is systematically controlled. Furthermore, the effects of nanoscale inhomogeneity on the Berry curvature near the Fermi surface in SrRuO3 films are investigated. It is found that the high kinetic energy of the capping layer adatoms induces stoichiometric modification and nanoscale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer.11Nsciescopu