Guided-mode resonance pressure sensor based on a stretchable low-density polyethylene film.

In this study, we demonstrate a method to fabricate a guided-mode resonance (GMR) device on a flexible and transparent low-density polyethylene (LDPE) film and present the measurement results of this device as a pressure sensor. A simple thermal-nanoimprinting process was used to fabricate a grating structure on the LDPE film substrate. This very flexible film was attached to a glass plate using an adhesive and sacrificial layer for coating high-refractive-index titanic oxide on the grating surface to form the GMR device. The LDPE-GMR device was equipped with a gas chamber to act as a pressure sensor. When the pressure inside the chamber was increased, the grating period of the GMR sensor also increased, resulting in a shift in the resonance angle of the GMR device. Owing to the higher flexibility of the LDPE film, a better pressure detection sensitivity and resolution can be obtained. Using the transmitted-intensity detection approach, we show that the transmitted laser power changes proportionally with the pressure increase. The experimental results showed that the LDPE-GMR pressure sensor could achieve a sensitivity of 8.27 µW/mbar and a limit of detection of 0.012 mbar at a power meter noise of 0.1 µW.

Lattice-Matched AlInN/GaN/AlGaN/GaN Heterostructured-Double-Channel Metal-Oxide-Semiconductor High-Electron Mobility Transistors with Multiple-Mesa-Fin-Channel Array.

Multiple-mesa-fin-channel array patterned by a laser interference photolithography system and gallium oxide (Ga2O3) gate oxide layer deposited by a vapor cooling condensation system were employed in double-channel Al0.83In0.17N/GaN/Al0.18Ga0.82N/GaN heterostructured-metal-oxide-semiconductors (MOSHEMTs). The double-channel was constructed by the polarized Al0.18Ga0.82N/GaN channel 1 and band discontinued lattice-matched Al0.83In0.17N/GaN channel 2. Because of the superior gate control capability, the generally induced double-hump transconductance characteristics of double-channel MOSHEMTs were not obtained in the devices. The superior gate control capability was contributed by the side-wall electrical field modulation in the fin-channel. Owing to the high-insulating Ga2O3 gate oxide layer and the high-quality interface between the Ga2O3 and GaN layers, low noise power density of 8.7 × 10-14 Hz-1 and low Hooge's coefficient of 6.25 × 10-6 of flicker noise were obtained. Furthermore, the devices had a unit gain cutoff frequency of 6.5 GHz and a maximal oscillation frequency of 12.6 GHz.

Enhancement on the Surface Hydrophobicity and Oleophobicity of an Organosilicon Film by Conformity Deposition and Surface Fluorination Etching.

In this work, the surface morphology of a hydrophobic organosilicon film was modified as it was deposited onto a silver seed layer with nanoparticles. The surface hydrophobicity evaluated by the water contact angle was significantly increased from 100° to 128° originating from the surface of the organosilicon film becoming roughened, and was deeply relevant to the Ag seed layer conform deposition. In addition, the organosilicon film became surface oleophobic and the surface hydrophobicity was improved due to the formation of the inactive C-F chemical on the surface after the carbon tetrafluoride glow discharge etching. The surface hydrophobicity and oleophobicity of the organosilicon film could be further optimized with water and oleic contact angles of about 138° and 61°, respectively, after an adequate fluorination etching.

Effect of Silver Dopants on the ZnO Thin Films Prepared by a Radio Frequency Magnetron Co-Sputtering System.

Ag-ZnO co-sputtered films at various atomic ratios of Ag (Ag/(Ag + Zn) at.%) were prepared by a radio frequency magnetron cosputtering system, using the co-sputtered targets of Ag and ZnO. The activation of the Ag acceptors (AgZn) and the formation of the Ag aggregations (Ag°) in the ZnO matrix were investigated from XRD, Raman scattering, and XPS measurements. The Ag-ZnO co-sputtered film behaving like a p-type conduction was achievable after annealing at 350 °C under air ambient for 1 h.

Characterization of an Amorphous Titanium Oxide Film Deposited onto a Nano-Textured Fluorination Surface.

The photocatalytic activity of an amorphous titanium oxide (a-TiOx) film was modified using a two-step deposition. The fluorinated base layer with a nano-textured surface prepared by a selective fluorination etching process acted as growth seeds in the subsequent a-TiOx deposition. A nanorod-like microstructure was achievable from the resulting a-TiOx film due to the self-assembled deposition. Compared to the a-TiOx film directly deposited onto the untreated base layer, the rate constant of this fluorinate-free a-TiOx film surface for decomposing methylene blue (MB) solution that was employed to assess the film's photocatalytic activity was markedly increased from 0.0076 min-1 to 0.0267 min-1 as a mechanism for the marked increase in the specific surface area.

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO2 Nanocomposite Structure.

This study achieved a nanocomposite structure of nickel oxide (NiO)/titanium dioxide (TiO2) heterojunction on a TiO2 film surface. The photocatalytic activity of this structure evaluated by decomposing methylene blue (MB) solution was strongly correlated to the conductive behavior of the NiO film. A p-type NiO film of high concentration in contact with the native n-type TiO2 film, which resulted in a strong inner electrical field to effectively separate the photogenerated electron-hole pairs, exhibited a much better photocatalytic activity than the controlled TiO2 film. In addition, the photocatalytic activity of the NiO/TiO2 nanocomposite structure was enhanced as the thickness of the p-NiO film decreased, which was beneficial for the migration of the photogenerated carriers to the structural surface.

Origin of the Electroluminescence from Annealed-ZnO/GaN Heterojunction Light-Emitting Diodes.

This paper addressed the effect of post-annealed treatment on the electroluminescence (EL) of an n-ZnO/p-GaN heterojunction light-emitting diode (LED). The bluish light emitted from the 450 °C-annealed LED became reddish as the LED annealed at a temperature of 800 °C under vacuum atmosphere. The origins of the light emission for these LEDs annealed at various temperatures were studied using measurements of electrical property, photoluminescence, and Auger electron spectroscopy (AES) depth profiles. A blue-violet emission located at 430 nm was associated with intrinsic transitions between the bandgap of n-ZnO and p-GaN, the green-yellow emission at 550 nm mainly originating from the deep-level transitions of native defects in the n-ZnO and p-GaN surfaces, and the red emission at 610 nm emerging from the Ga-O interlayer due to interdiffusion at the n-ZnO/p-GaN interface. The above-mentioned emissions also supported the EL spectra of LEDs annealed at 700 °C under air, nitrogen, and oxygen atmospheres, respectively.