The influence of sputtering pressure on the structural and electrical properties of In–Ga–Zn–O (IGZO) thin films deposited by high-power pulsed magnetron sputtering (HPPMS) was systematically investigated. By controlling the deposition pressure between 0.65 and 3.0 Pa, the plasma characteristics during HPPMS deposition were significantly modified. Optical emission spectroscopy revealed that lower pressures increased the relative contribution of emissions from ionized species, suggesting enhanced plasma activity during film growth. Despite substrate temperatures remaining below 70 °C throughout deposition, X-ray diffraction analysis showed the emergence of structurally ordered and partially crystallized IGZO phases within an optimized pressure region around 1.5 Pa. X-ray photoelectron spectroscopy further demonstrated that the optimized growth condition promoted metal-oxygen bonding while reducing the higher-binding-energy O 1s component associated with oxygen-deficient bonding environments. Following post-deposition annealing, IGZO thin-film transistors fabricated from films deposited at 1.5 Pa exhibited the smallest subthreshold swing among all investigated conditions. These improvements are associated with enhanced structural ordering and reduced defect density resulting from pressure-controlled film growth. The present results demonstrate that sputtering pressure plays a critical role in governing the structural evolution of IGZO thin films during HPPMS deposition and provide further insight into pressure-controlled growth behavior under low-temperature deposition conditions.
Hybrid metal–polymer structures combining titanium alloys and Polyether Ether Ketone (PEEK) have attracted increasing attention for biomedical implants because they can reduce stress shielding while maintaining sufficient mechanical strength. Direct bonding of Ti-6Al-4 V (Ti-64) titanium alloy to PEEK was successfully demonstrated via hot pressing following pre-treatment using a non-thermal atmospheric pressure RF plasma jet. This study investigated the surface modifications on both materials and their influence on joint strength, aiming to establish a viable method for hybrid biomedical implants. Plasma treatment applied solely to the Ti-64 side led to TiO2 and Al2O3 oxide layer formation but resulted in negligible bond strength (≈0.8 MPa). Conversely, plasma treatment on the PEEK side resulted in a significant enhancement, and the tensile shear strength reached a maximum of 11.2 MPa. This strength was high enough for failure to occur within the PEEK bulk itself. Surface analysis confirmed that the enhancement was primarily chemical. While the Ti-64 surface roughness (Ra) remained nearly constant, XPS analysis revealed that the plasma jet introduced new oxygen-containing functional groups (O-C=O) onto the PEEK surface. The resulting bond strength showed a strong correlation with the density of these polar groups. The bonding mechanism is considered to be consistent with hydrogen bonding and other secondary interactions between the oxygen-containing functional groups introduced on PEEK and the oxide sites on the Ti-64 surface. This method offers excellent strength and maintains sufficient biocompatibility, validating its application potential in hybrid implant technologies. Unlike commercially pure titanium (TP340), Ti-64 contains alloying elements such as vanadium, whose oxidation behavior and surface segregation characteristics significantly affect the chemistry of the passive oxide layer. In this study, particular attention is given to the role of vanadium oxides in modifying interfacial interactions, which has not been systematically analyzed in previous TP340/PEEK systems.
Spatial distributions of minority carrier lifetimes ( tau(minority)) in nanowire-based GaN and InGaN/GaN multiple quantum shells grown on a GaN template were investigated using macroarea time-resolved photoluminescence and spatio-time-resolved cathodoluminescence (STRCL) measurements. The tau(minority )value of the GaN nanowires (approximately 101 ps) was uniformly distributed along the nanowire altitude and was longer than that of the GaN template (approximately 24 ps), reflecting the dislocation-free nature of nanowire structures. The tau(minority )value of the InGaN wells grown under optimized conditions was also uniform along the height (approximately 86 ps). However, the value was more than one order of magnitude shorter than that of the planar c-plane single quantum well and several times shorter than that of the planar m-plane multiple quantum wells. Single tau(minority )components observed for both GaN nanowires and InGaN wells, consistently confirmed by both macroarea time-resolved photoluminescence and STRCL measurements, indicated that spatial variations of N(MGRC )within individual nanowires or across the chip were likely negligible and that surface recombination effects were insignificant. Based on the quantified tau(minority), the concentrations of potentially dominant midgap recombination centers (MGRCs) in the GaN nanowires, which are likely divacancies comprising a Ga vacancy (V-Ga) and a N vacancy (V-N) [VGaVN] and/or carbon impurities resulting from extremely low V/III ratios, are estimated to be in the first half of 10(16) cm(-3). The MGRC concentration in the InGaN wells was estimated to be several times higher than that in the planar m-plane multiple quantum wells. Reducing the MGRC concentrations is essential for achieving highly luminescent InGaN/GaN multiple quantum shells.
Aim Traditional Japanese (Kampo) medicines containing ephedra (KE) are prescribed for cold during pregnancy; however, detailed safety information on their use in pregnant women is lacking. This study aimed to clarify the association between prescription of KE during the first trimester of pregnancy and major congenital malformations (MCMs) in newborns.Methods Data from a large Japanese administrative claims database were analyzed: we included records of pregnant women who continued to be covered in the same health insurance society from 3 months before pregnancy until delivery, who gave birth between 2010 and 2019; the selected records included data relating to the infants until first year from birth. Pregnant women who were prescribed acetaminophen, commonly used to treat colds, in the first trimester of pregnancy and their infants were treated as the controls in our analysis.Results Of 75,398 infants, 4607 (6.1%) were diagnosed with MCMs within the first year of birth. Among the 7820 infants whose mothers were prescribed acetaminophen, 497 (6.4%) had MCMs. Of the 4772 infants were born to women prescribed KE, among whom 327 (6.9%) had MCMs. adjusting for covariates with propensity score overlap weights identified no significant difference in MCM risk between the two types of prescriptions (overlap-weighted odds ratio 1.077, 95% confidence interval 0.932-1.245).Conclusion The results of this study indicated that the risk of MCMs did not differ between women prescribed KE and those prescribed acetaminophen in the first trimester of pregnancy.
Plasma-grown carbon nanostructures exhibit diverse morphologies depending on plasma conditions. We investigate the transition from vertically aligned carbon nanowalls (CNWs) to branched CNWs and isotropic porous three-dimensional graphene using inductively coupled plasma chemical vapor deposition. The effects of argon flow rate, hydrogen addition, and total pressure were systematically examined. Hydrogen-added, argon-lean conditions stabilized vertical CNWs, whereas an increase in argon contribution and/or pressure promoted branching and isotropic structures. Image-based analysis of cross-sectional scanning electron microscopy images enabled quantitative evaluation of structural anisotropy and revealed a continuous transition governed by gas composition and total pressure.
