TiO2 photocatalysis and related surface phenomena

羟氨苄青霉素引起大疱性类天疱疮样疹

The present status and prospects for further development of polycrystalline or amorphous transparent conducting oxide (TCO) semiconductors used for practical thin-film transparent electrode applications are presented in this paper. The important TCO semiconductors are impurity-doped ZnO, In2O3 and SnO2 as well as multicomponent oxides consisting of combinations of ZnO, In2O3 and SnO2, including some ternary compounds existing in their systems. Development of these and other TCO semiconductors is important because the expanding need for transparent electrodes for optoelectronic device applications is jeopardizing the availability of indium-tin-oxide (ITO), whose main constituent, indium, is a very expensive and scarce material. Al- and Ga-doped ZnO (AZO and GZO) semiconductors are promising as alternatives to ITO for thin-film transparent electrode applications. In particular, AZO thin films, with a low resistivity of the order of 10−5 Ω cm and source materials that are inexpensive and non-toxic, are the best candidates. However, further development of the deposition techniques, such as magnetron sputtering or vacuum arc plasma evaporation, as well as of the targets is required to enable the preparation of AZO and GZO films on large area substrates with a high deposition rate.

https://iopscience.iop.org/article/10.1088/0268-1242/20/4/004/pdf

Transparent conducting oxide semiconductors for transparent electrodes

https://chemistry.beloit.edu/classes/nanotech/ZnO/mattoday10_05_40.pdf

ZnO - nanostructures, defects, and devices

Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

A review of Ga2O3 materials, processing, and devices

Highly transparent and conductive rare earth-doped ZnO thin films prepared by magnetron sputtering

High-efficiency heterojunction solar cells consisting of a nondoped Ga2O3 thin film as an n-type semiconductor layer and a p-type Cu2O sheet as the active layer as well as the substrate, prepared by thermally oxidizing a Cu sheet, are demonstrated. The use of an n-type Ga2O3 thin film can greatly improve the performance of n-Ga2O3/p-Cu2O heterojunction solar cells. The highest efficiency of 5.38% was obtained in an Al-doped ZnO/Ga2O3/Cu2O heterojunction solar cell fabricated with an n-Ga2O3 thin-film layer prepared at room temperature with a thickness of 75 nm by a pulsed laser deposition method.

https://iopscience.iop.org/article/10.7567/APEX.6.044101/pdf

High-Efficiency Cu2O-Based Heterojunction Solar Cells Fabricated Using a Ga2O3 Thin Film as N-Type Layer

High conversion efficiencies were achieved in low cost n–p heterojunction oxide solar cells with an Al-doped ZnO (AZO)/non-doped ZnO (ZO)/Cu2O structure. This achievement was made possible by the formation of an n-ZO thin-film layer, prepared with an appropriate thickness by low damage deposition, on high quality Cu2O sheets produced by the thermal oxidization of copper sheets: n-ZO thin film optimal thickness ranges from 30 to 50 nm. Photovoltaic characteristics such as an open circuit voltage of 0.69 V, a fill factor of 0.55 and a conversion efficiency of 3.83% were attained under simulated AM1.5G solar illumination.

https://iopscience.iop.org/article/10.1143/APEX.4.062301/pdf

High-Efficiency Oxide Solar Cells with ZnO/Cu2O Heterojunction Fabricated on Thermally Oxidized Cu2O Sheets

The work function of transparent conducting multicomponent oxide (TCO) films is reported. TCO films consisting of binary oxides, such as In 2 O 3 , SnO 2 and ZnO, and ternary oxides, such as Zn 2 In 2 O 5 , In 4 Sn 3 O 12 , GaInO 3 , ZnSnO 3 and MgIn 2 O 4 , were prepared by magnetron sputtering. In addition, transparent conducting films consisting of multicomponent oxides composed of combinations of these binary or ternary oxides were also prepared by magnetron sputtering. The work function of these TCO films was measured by ultraviolet photoelectron spectroscopy operated in air. It was found that the work function as well as the electrical, optical and chemical properties of transparent conducting multicomponent oxide films could be controlled by varying the chemical composition.

Toshihiro Miyata

Papers

Highly transparent and conductive rare earth-doped ZnO thin films prepared by magnetron sputtering

High-Efficiency Cu2O-Based Heterojunction Solar Cells Fabricated Using a Ga2O3 Thin Film as N-Type Layer

High-Efficiency Oxide Solar Cells with ZnO/Cu2O Heterojunction Fabricated on Thermally Oxidized Cu2O Sheets

Work function of transparent conducting multicomponent oxide thin films prepared by magnetron sputtering

Present status and future prospects for development of non- or reduced-indium transparent conducting oxide thin films