The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Heterogeneous photocatalyst materials for water splitting

Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers1. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H)2,3,4,5 and organic semiconductors2,6,7,8,9,10 have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V-1 s-1, which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6–9 cm2 V-1 s-1, and device characteristics are stable during repetitive bending of the TTFT sheet.

Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

We report the fabrication of transparent field-effect transistors using a single-crystalline thin-film transparent oxide semiconductor, InGaO 3 (ZnO) 5 , as an electron channel and amorphous hafnium oxide as a gate insulator. The device exhibits an on-to-off current ratio of ∼10 6 and a field-effect mobility of ∼80 square centimeters per volt per second at room temperature, with operation insensitive to visible light irradiation. The result provides a step toward the realization of transparent electronics for next-generation optoelectronics.

http://science.sciencemag.org/content/sci/300/5623/1269.full.pdf

Thin-Film Transistor Fabricated in Single-Crystalline Transparent Oxide Semiconductor

Novel film growth technique of single crystalline In2O3(ZnO)m (m= integer) homologous compound

A light emitting device having practical light emission characteristics is obtained without epitaxial growth. A quantum dot-dispersed light emitting device of the invention includes a substrate 11, an electron injection electrode 12, a hole injection electrode 14, and an inorganic light emitting layer 13 disposed so as to be in contact with both the electrodes. The inorganic light emitting layer 13 contains an ambipolar inorganic semiconductor material and nanocrystals 15 dispersed as luminescent centers in the ambipolar inorganic semiconductor material and is configured so as to be capable of light emission without having, at the interface with the electron injection electrode and/or the hole injection electrode, epitaxial relation therewith.

Quantum Dot-Dispersed Light Emitting Device, and Manufacturing Method Thereof

Electro-conductive oxides showing excellent electro-conductivity, electrodes using the electro-conductive oxide and methods for manufacturing the same are described. The electro-conductive oxides are represented by the general formula: M(1) x M(2) y In z O.sub.(x+3y/2+3z/2)-d. The above electro-conductive oxides show not only excellent electro-conductivity but also excellent transparency all over the visible region and therefore they are particularly useful as, for example, electrodes for liquid crystal displays, EL displays and solar cells, which require light transmission.

Electro-conductive oxides and electrodes using the same

Powder materials having the composition Pb0.88Ba0.12(Zn1/3Nb2/3)0.30(Mg1/3Nb2/3)0.50Ti0.20O3 were prepared by a two-step calcination method. All the constituent oxides, except for PbO, were precalcined, and then the resulting mixtures were postcalcined with PbO to obtain powders having the desired composition. A series of experimental studies of the powder and the ceramic showed that samples fabricated by the present method had better properties in terms of perovskite phase purity, sinterability, breakdown voltage and dielectric constant, compared to those prepared by the conventional method using one-step calcination.

Preparation of ferroelectric relaxor Pb(Zn1/2Nb2/3)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 by two-step calcination method

It has been confirmed that an n type ZnO film formed on an SrCu2O2 film will produce diode characteristics, without light emitting from a diode confirmed. A semiconductor ultraviolet luminous element characterized by comprising a p-n junction formed by laminating one of p-type semiconductors, respectively consisting of SrCu2O2, CuAlO2 or CuGaO2, on an n-type ZnO layer laminated on a transparent substrate and indicating luminous characteristics. The transparent substrate is preferably a single crystal substrate, especially, yttria partially stabilized zirconia (YSZ) (111) substrate flattened in an atomic state. An n-type ZnO film is formed on a transparent substrate at a substrate temperature of 200-1200°C, and a p-type semiconductor layer consisting of SrCu2O2, CuAlO2 or CuGaO2 is further formed on the film. It may also be possible to form an n-type ZnO film, without heating a substrate, and irradiate the surface of the ZnO film with ultraviolet light to promote crystallization.

Masahiro Orita

Papers

Novel film growth technique of single crystalline In2O3(ZnO)m (m= integer) homologous compound

Quantum Dot-Dispersed Light Emitting Device, and Manufacturing Method Thereof

Electro-conductive oxides and electrodes using the same

Preparation of ferroelectric relaxor Pb(Zn1/2Nb2/3)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 by two-step calcination method

Light emitting diode and semiconductor laser