In the past several years, research in each of the wide‐band‐gap semiconductors, SiC, GaN, and ZnSe, has led to major advances which now make them viable for device applications. The merits of each contender for high‐temperature electronics and short‐wavelength optical applications are compared. The outstanding thermal and chemical stability of SiC and GaN should enable them to operate at high temperatures and in hostile environments, and also make them attractive for high‐power operation. The present advanced stage of development of SiC substrates and metal‐oxide‐semiconductor technology makes SiC the leading contender for high‐temperature and high‐power applications if ohmic contacts and interface‐state densities can be further improved. GaN, despite fundamentally superior electronic properties and better ohmic contact resistances, must overcome the lack of an ideal substrate material and a relatively advanced SiC infrastructure in order to compete in electronics applications. Prototype transistors have been fabricated from both SiC and GaN, and the microwave characteristics and high‐temperature performance of SiC transistors have been studied. For optical emitters and detectors, ZnSe, SiC, and GaN all have demonstrated operation in the green, blue, or ultraviolet (UV) spectra. Blue SiC light‐emitting diodes (LEDs) have been on the market for several years, joined recently by UV and blue GaN‐based LEDs. These products should find wide use in full color display and other technologies. Promising prototype UV photodetectors have been fabricated from both SiC and GaN. In laser development, ZnSe leads the way with more sophisticated designs having further improved performance being rapidly demonstrated. If the low damage threshold of ZnSe continues to limit practical laser applications, GaN appears poised to become the semiconductor of choice for short‐wavelength lasers in optical memory and other applications. For further development of these materials to be realized, doping densities (especially p type) and ohmic contact technologies have to be improved. Economies of scale need to be realized through the development of larger SiC substrates. Improved substrate materials, ideally GaN itself, need to be aggressively pursued to further develop the GaN‐based material system and enable the fabrication of lasers. ZnSe material quality is already outstanding and now researchers must focus their attention on addressing the short lifetimes of ZnSe‐based lasers to determine whether the material is sufficiently durable for practical laser applications. The problems related to these three wide‐band‐gap semiconductor systems have moved away from materials science toward the device arena, where their technological development can rapidly be brought to maturity.

Large‐band‐gap SiC, III‐V nitride, and II‐VI ZnSe‐based semiconductor device technologies

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

Photoelectrochemical (PEC) water splitting for hydrogen production is a promising technology that uses sunlight and water to produce renewable hydrogen with oxygen as a by-product. In the expanding field of PEC hydrogen production, the use of standardized screening methods and reporting has emerged as a necessity. This article is intended to provide guidance on key practices in characterization of PEC materials and proper reporting of efficiencies. Presented here are the definitions of various efficiency values that pertain to PEC, with an emphasis on the importance of solar-to-hydrogen efficiency, as well as a flow chart with standard procedures for PEC characterization techniques for planar photoelectrode materials (i.e., not suspensions of particles) with a focus on single band gap absorbers. These guidelines serve as a foundation and prelude to a much more complete and in-depth discussion of PEC techniques and procedures presented elsewhere.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400005653

Accelerating materials development for photoelectrochemical hydrogen production: Standards for methods, definitions, and reporting protocols

Photocatalytic approaches, that is the reaction of light-produced charge carriers at a semiconductor surface with their environment, currently attract an extremely wide scientific interest. This is to a large extent due to the high expectations: i) to convert sunlight directly into an energy carrier (H(2)), ii) to stimulate chemical synthetic reactions, or iii) to degrade unwanted environmental pollutants. Since the early reports in 1972, TiO(2) has been the most investigated photocatalytic material by far; this originates from its outstanding electronic properties that allow for a wide range of applications. Not only the material, but also its structure and morphology, can have a considerable influence on the photocatalytic performance of TiO(2). In recent years, particularly 1D (or pseudo 1D) structures such as nanowires and nanotubes have received great attention. The present Review focuses on TiO(2) nanotube arrays (and similar structures) that grow by self-organizing electrochemistry (highly aligned) from a Ti metal substrate. Herein, the growth, properties, and applications of these tubes are discussed, as well as ways and means to modify critical tube properties. Common strategies are addressed to improve the performance of photocatalysts such as doping or band-gap engineering, co-catalyst decoration, junction formation, or applying external bias. Finally, some unique applications of the ordered tube structures in various photocatalytic approaches are outlined.

A Review of Photocatalysis using Self-organized TiO2 Nanotubes and Other Ordered Oxide Nanostructures

▪ Abstract The formation of switchable holographic gratings from polymer-dispersed liquid crystals (H-PDLCs) allows for the development of switchable transmissive and reflective diffractive optics. These structures are created by the coherent interference of laser radiation within a syrup containing photoreactive monomer, initiator, and liquid crystal. Local differences in photopolymerization rates induce phase separation of discrete LC domains to occur periodically commensurate with the period of the interference pattern. These spatially periodic gratings of nano-scale sized LC domains can be formed on grating length scales ranging from 100 nm to microns depending on the optics of fabrication. True Bragg gratings are formed with spacings typically less than 1 μm. Owing to the refractive profile generated by this periodic two-phase structure, diffraction of light occurs. Electrical switching of the average director orientation within the LC domains results in a modulation of diffracted radiation. This tec...

Holographic Polymer-Dispersed Liquid Crystals (H-PDLCs)1

Doping of nitrogen acceptors into ZnSe using a radical beam during MBE growth

Hydrogen gas generation from a counterelectrode was clearly observed for the first time using light-illuminated n-type GaN as a working photoelectrode in an electrolyte. The application of extra bias to a working electrode was required to obtain a sufficient volume of generated gas. The reactions at the GaN photoelectrode were both GaN decomposition and water oxidization, simultaneously.

https://iopscience.iop.org/article/10.1143/JJAP.44.L543/pdf

Hydrogen Gas Generation by Splitting Aqueous Water Using n-Type GaN Photoelectrode with Anodic Oxidation

In a liquid crystal display device in which a plurality of liquid crystal layers are stacked on a substrate, a method for bonding a film for sealing liquid crystal to supporting members is improved and the fabrication cost is thereby reduced, in order to provide a reflective type liquid crystal display device that achieves a bright display image and causes no parallax problem, and to provide a reducing method of the device. The liquid crystal display device comprises a substrate, a resin film, a multiplicity of columnar supporting members, an adhesive layer, and a liquid crystal layer. The substrate comprises a pixel electrode and a driving element connected to the pixel electrode, both formed on the upper surface of the substrate. The resin film comprises a common electrode provided on the upper surface of the film, and is disposed upwardly with respect to the substrate. The supporting members are provided on the substrate so as to support the resin film. The adhesive layer is provided between each of the supporting members and the resin film so as to bond the resin film to each of the supporting members. The liquid crystal layer is produced by filling liquid crystal between the substrate and the resin film. The adhesive layer is composed of a thermoplastic material, and characterized in that a bonding state of the resin film and the supporting members is realized by making the adhesive layer have a thermoplastic characteristic.

Liquid crystal display device and method of manufacturing the same

PROBLEM TO BE SOLVED: To obtain a frontlight type illuminator suppressing deterioration of display contrast, a touch panel with illumination and a reflective liquid crystal display device incorporating them. SOLUTION: A frontlight type illuminator 100, which is arranged on the front side of a liquid crystal display device 200, is equipped with a light guide plate 1, a plurality of light emitting layers 5 which is provided on one plane, placed opposite to the other plane confronted with the liquid crystal display device 200, of the light guide plate 1 and emits a light to illuminate the liquid crystal display device 200 when illuminated with a light, a lightproof layer 6 which is provided so as to cover the front surface of the light emitting layers 5 and shade a light outgoing toward the front surface side of the light emitting layers 5 and a line light source 2 which is provided on an end face of the light transmission plate 1 and irradiates light to excite the light emitting layers 5 and make them emit a light. Thereby it is possible to uniformly illuminate even a large area liquid crystal display device with fine display contrast or the like.

Illuminator, touch panel with illumination and reflective liquid crystal display device

This study has investigated the effects of the material systems involved in the fabrication processes on the polarization behavior of a volume holographic grating. The diffraction efficiency of the gratings fabricated using prepolymer/liquid crystal mixtures shows strong dependence on the polarization of incoming light. Depending on the materials used in the formation of a grating, the diffraction properties are such that either p- or s-polarized light is strongly diffracted while the light with the other polarization is very weakly diffracted. The magnitude of the dependence on the polarization is greatly affected by the type of monomers, liquid crystals and substrates. The comparison of various types of monomers added to the base prepolymer mixtures, two distinctly different types of liquid crystals and glass slides and indium-tin oxide (ITO) coated glass as substrates was carried out using polyester-based and urethane-based oligomers.

Effects of Material Systems on the Polarization Behavior of Holographic Polymer Dispersed Liquid Crystal Gratings

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