Transparent Electrodes In Flat Panel Research Articles

Effect of Calcinations Temperature on ZnO:Co Nanostructured Thin Films Prepared By Sol – Gel Method.

Nanostructured ZnO thin films were developed on medical-glass substrates using a sol gel dip coating process and calcinated at various temperatures (350, 450, and 550 C°). The impact of Co doping and effect temperature calcination on the structural, optical and electrical properties of ZnO:Co nanostructured thin films were investigated using XRD, SEM, Hall effect, and UV-Visible spectra measurements. Both nanostructured films have hexagonal-wurtzite crystals composition according to XRD analysis with the average crystallite sizes of ZnO:Co nanostructured thin films are of (26.7-102.1) nm. The FESEM findings show that the undoped ZnO thin film has the smoothest and more regular surface compared to the doped ZnO films, indicating that both films with nanoscale ZnO particles. The average transmittance of all films is about 69–91 % in the visible range and the band gap energy decreased from 3.283 to 3.205 eV with increase of temperature calcination. The Hall impact indicates that all thin films are n-type and the electrical conductivity increase from (12.4-16.2) in the ZnO:Co thin films. This one of the outstanding property of ZnO thin films, both undoped and doped with cobalt, enables the fabrication of transparent electrodes for flat panel displays, metal-insulator-semiconductor diodes, and solar cells.

인라인 마그네트론 스퍼티링에 의한 ITO/Ag/ITO 다층 구조 투명전극의 최적화에 관한 연구

Indium tin oxide (ITO) thin films show a low sheet resistance and high transmittance in the visible range of the spectrum. Therefore, they play an important role as transparent electrodes for flat panel displays. However, their resistivity is rather high for use as a transparent electrode in large displays. One way to improve electrical and optical properties in large displays is to use ITO/Ag/ITO multilayer films. ITO/Ag/ITO multilayer films have lower sheet resistance than single layer ITO films with the same thickness. Prior to the ITO/Ag/ITO multilayer experiments, optimal condition for thickness change are necessary. Their thicknesses were deposited differently in order to analyze electrical and optical properties. However, when optimal single film characteristics are applied to ITO/Ag/ITO multilayer films, other phenomena appeared. After analyzing the electrical and optical properties by changing ITO and Ag film thickness, ITO/Ag/ITO multilayer films were optimized. By combining ITO film at <TEX>$586\;{\AA}$</TEX> and Ag film at 10 nm, the ITO/Ag/ITO multilayer films showed optimized high optical transmittance of 87.65%, and the low sheet resistance of <TEX>$5.5{\Omega}/sq$</TEX>.

Electrical, optical, and structural properties of thin films with tri-layers of AZO/ZnMgO/AZO grown by filtered vacuum arc deposition

Abstract Transparent conductive oxides (TCO) are indispensable as front electrode for most of thin film electronic devices such as transparent electrodes for flat panel displays, photovoltaic cells, windshield defrosters, transparent thin film transistors, and low emissivity windows. Thin films of aluminum-doped zinc oxide (AZO) have shown to be one of the most promising TCOs. In this study, three layered Al-doped ZnO (AZO)/ZnMgO/AZO heterostructures were prepared by filtered cathodic arc deposition (FCAD) on glass substrates. The objective is to find a set of parameters that will allow for improved optical and electrical properties of the films such as low resistivity, high mobility, high number of charge carriers, and high transmittance. We have investigated the effect of modifications in thickness and doping of the ZnMgO inner layer on the structural, electrical, and optical characteristics of the stacked heterostructures.

Graphene and graphene/polymer nanocomposites

the graphite by Geim and Novoselov group in 2004, graphene triggered a gold rush for exploiting its possible applications. A search with graphene as a key word using the SciFinder shows even a tremendous increase of publication from 3900 (2010) to 9500 (2011) as they were awarded the novel prize in physics in 2010. Graphene is a one-atom thick, two-dimensional sheet composed of sp2 hybridized carbon atoms arranged in a honeycomb structure. It has combined benefits of layered silicates and carbon nanotubes, and is considered as the most promising reinforcing and functional filler of polymers. Large area graphene is typically produced by bottom-up method such as chemical vapor deposition while flake type by top-down method consisting of oxidation of graphite, exfoliation of graphite oxide (GO) by sonication in liquid media, and reduction. Rapid thermal expansion of GO in inert atmosphere gives thermal exfoliation and reduction simultaneously and is suited for economical, large scale production without using any dispersion media. The oxygen groups on the surface remaining upon reduction of GO enable dispersion in solvent and water and provide sites for chemical functionalization which allows covalent bonding with reactive polymer function (Advanced Materials, DOI: 10.1002/adma.201102036). For example, polyure thanes (PUs) are readily blended with graphene, and hydroxyl functions of graphene react with isocyanate termini of PU to form graphene/PU chemical hybrids. It is vital to control the type and amount of reactive sites on the graphene surface and edges. Markets for graphene are opened for i) energy saving electrodes as secondary cells for smartphone, notebook, electric car and solar cell, ii) transparent electrodes for flat panel (LCD, OLED) and touch screen, and iii) semiconductors. If graphene thin layer is properly deposited on glass or polymer surfaces, flexible displays, thin film transistors, and photovoltaic and LCD devices will be made possible (Macromolecules, DOI: 10.1021/ma100572e). Graphene can be used as functional reinforcement for polymer to include packaging, gasketing, automotive, aircraft, ink, painting, sensor etc. When graphene is doped to PU, electrically and infrared light triggered shape memory material is synthesized where graphene provides crosslinks, strain energy storage and light absorption. However, low cost and large production of graphene will only expedite its applications. Otherwise, ‘It is a dream. The prospect is so far beyond the horizon that we cannot even assess it properly’, as Geim says.

Processing Parameters and Property of AZO Thin Film Prepared by Magnetron Sputtering

As we all know, transparent and conductive Al:ZnO (AZO) films are being considered for manufacturing transparent electrodes in flat panel displays, solar cells and organic light emitting diodes due to their high electro optical quality, high material availability and low material cost for large area applications. In this experiment, AZO thin films were prepared on glass substrate by Magnetron Sputtering method with a 2wt % Al -doped ceramic target .The processing parameters on electrical properties of AZO thin film were investigated. When processing pressure is 0.8Pa,the sputtering power is 225W,the temperature of substrate is 225°, the AZO thin films have a lowest resistivity of 9.81×10−4 Ω.cm and visible light transmittance of more than 85%.

Characterization of TiO 2/Au/TiO 2 films deposited by magnetron sputtering on polycarbonate substrates

Transparent and conducting TiO 2/Au/TiO 2 (TAuT) films were deposited by reactive magnetron sputtering on polycarbonate substrates to investigate the effect of the Au interlayer on the optical, electrical, and structural properties of the films. In TAuT films, the Au interlayer thickness was kept at 5 nm. Although total thickness was maintained at 100 nm, the stack structure was varied as 50/5/45, 70/5/25, and 90/5/5 nm. In XRD pattern, the intermediate Au films were crystallized, while all TAuT films did not show any diffraction peaks for TiO 2 films with regardless of stack structure. The optical and electrical properties were dependent on the stack structure of the films. The lowest sheet resistance of 23 Ω/□ and highest optical transmittance of 76% at 550 nm were obtained from TiO 2 90 nm/Au 5 nm/TiO 2 5 nm films. The work function was dependent on the film stack. The highest work function (4.8 eV) was observed with the TiO 2 90 nm/Au 5 nm/TiO 2 5 nm film stack. The TAuT film stack of TiO 2 90 nm/Au 5 nm/TiO 2 5 nm films is an optimized stack that may be an alternative candidate for transparent electrodes in flat panel displays.

The Removal of Tin from ITO-scrap via Ozonization

Flat panel display applications for indium in the form of Indium Tin Oxide (ITO) are the most important end uses, more than one-half of the world’s indium consumption. The glass plate coated with ITO which is formed by doping indium oxide with approximately 10% of tin oxide, exhibits electrical conductivity without significantly affecting transparency, and has been used as transparent electrodes for flat panel displays. ITO films are generally fabricated by DC magnetron sputtering using ITO ceramic target. Magnetron sputtering is favoured because it is easily applied to large area with good uniformity. However, ITO targets should be replaced before a large portion of ITO material (60 ~ 70%) has been used because of race track formation. 4-6 So, it might be said that the recycling of unused ITO target is indispensable as indium is a trace element and very expensive. As shown in In1.82Sn0.18O3 obtained by doping indium oxide with approximately 10% of tin oxide, tin is the major impurity in recovery process of indium metal from ITO target-scrap. Indium and tin are chemically very similar and separation one from the other in solution is a knotty problem. Rapid separation of indium from tin by sublimation has been reported. 7

The Removal of Tin from ITO-scrap Using Molten NaOH

Indium demand has grown abruptly in the last few years at an average of ten percent per year. Consumption of indium is expected to increase throughout the next decade, especially by dint of growth for liquid crystal displays, high-definition television, semiconductor materials, batteries, low-temperature solders, and electronic application. Indium is used in various forms such as indium oxide/indium-tin oxide, indium metal and alloy, and indium compounds. 1,2 Indium-tin oxide (ITO) formed by doping indium oxide with approximately 10% of tin oxide, increases both electrical conductivity without significantly affecting transparency. Flat panel display applications for indium in the form of ITO are the most important end uses, more than onehalf of the world , s indium consumption. ITO, which has a high optical transparency and a high electrical conductivity, has been used as transparent electrodes for flat panel displays. ITO films are generally fabricated by DC magnetron sputtering using ITO ceramic target. Magnetron sputtering is favoured because it is easily applied to large area with good uniformity. However, ITO targets should be replaced before a large portion of ITO material (60-70%) has been used because of race track formation. 3-5 So, it might be said that the recycling of unused ITO target is indispensable as indium is a trace element and very expensive. As shown in In1.82Sn0.18O3 obtained by doping indium oxide with approximately 10% of tin oxide, tin is the major impurity in recovery process of indium metal from ITO target-scrap. Indium and tin are chemically very similar and separation one from the other in solution is a knotty problem. Tin has been removed from residue of acetate leaching by chemical replacement with zinc in 5-20% HCl. 6 Another method concerns neutralization of solutions containing tin to pH 1 followed by cementation with indium 7,8 or by treating with NaOH to a pH value of 2.8. 9,10 In this paper, I demonstrate a new method to remove tin and purify indium metal from ITO target scrap using molten NaOH.

Optical and Structural Properties of Single Phase Epitaxial p‐Type Transparent Oxide Thin Films

Transparent conductive oxides (TCOs) are widely used in optoelectronic devices. For example, Sn-doped In2O3 (indium tin oxide, ITO), Al-doped ZnO, and F- or Sb-doped SnO2 have been practically adopted as transparent electrodes in flat panel displays, solar cells, and organic light-emitting diodes. [1] As these materials are all electron doped, the electrical conductivity of these materials is controlled by the conduction of electrons. In other words, they are n-type TCOs. In order to fully explore the potential applications of TCOs in transparent electronics, the development of p-type TCOs is critical as well. [2] For instance, the formation of active devices such as p–n junctions based on TCOs can lead to functional windows, where the junction not only transmits visible light but also generates electricity by the absorption of the ultraviolet (UV) radiation. [2] Since the discovery of p-type electrical conduction in the transparent CuAlO2 thin film, a class of delafossite AMO2 materials (A= Cu or Ag, M = Al, Ga, Fe, or In) has been extensively investigated in the last several years. [2–5] The crystal structure of delafossite CuAlO2 consists of an alternating stack of Cu ion layers and AlO2 octahedron layers. Each Cu atom is linearly coordinated with two oxygen atoms to form an O-Cu-O dumbbell unit placed parallel to the c-axis. O-atoms of O-Cu-O dumbbell link all Cu layers with the AlO2 layers. [2] Synthesizing thin film of this material is complicated due to the variety of possible Cu-Al-O phases. [6] A few attempts have been made to prepare CuAlO2 films using techniques such as pulsed laser deposition (PLD), DC- and rfsputtering, chemical vapor deposition (CVD), ion-exchange reactions, spray, and sol-gel methods. [2,5–18] The chemical solu

The design of ZnS/Ag/ZnS transparent conductive multilayer films

In this paper, a ZnS/Ag/ZnS multilayer system for the transparent electrodes in flat panel displays was designed. The optical and electrical performance of an Ag and ZnS single layer films with nano-dimensions was investigated. The smallest thickness of the continuous single layer Ag film that could be deposited on SiO 2 surface by thermal evaporation is approximately 12 nm. The spectroscopic ellipsometry analysis indicated that the interlayer between the Ag and ZnS layer contains a physically mixed layer and a compound semiconductor layer. Based on these studies, according to the characteristic matrix theory, the design for the optimized system was carried out with complete searching strategy. A group of the optimized structures with good selective filtering performance were successfully prepared, including some new extremely asymmetric multilayer structures. These have low sheet resistance of 3 Ω/□ and a good spectral selectivity performance with luminous transmittance T lum approximately 90% and the reflectance near infrared region above 90%. The figure of merit F TC used for evaluating transparent electrodes reached 7.3×10 −2 at 550 nm wavelength.

Large area glass coating

Abstract Since the end of the seventies vacuum coating technology for the deposition of optical thin films on large area glass substrates has enjoyed a steady growth. Nowadays, the main applications are low emissivity and solar control thin film systems on architectural glass as well as transparent electrodes for flat panel displays. Future markets like electrochromic or anti-reflective coatings appear on the horizon; the latter covering a wide range of products like picture frames, show-cases, shop windows, and all kinds of data and TV screens. The paper gives an introduction into the above-mentioned applications and outlines the present state of sputtering technology for large area glass coating.