Home About us Contact
|
Home About us Contact | ||
|
|
||
Optical Transmittance (optical + transmittance)
Selected AbstractsEffects of Individual Layer Thickness on the Microstructure and Optoelectronic Properties of Sol,Gel-Derived Zinc Oxide Thin FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2008Noureddine Bel Hadj Tahar Zinc oxide (ZnO) thin films were prepared under different conditions on glass substrates using a sol,gel process. The microstructure of ZnO films was investigated by means of diffraction analysis, and plan-view and cross-sectional scanning electron microscopy. It was found that the preparation conditions strongly affected the structure and the optoelectronic properties of the films. A structural evolution in morphology from spherical to columnar growth was observed. The crystallinity of the films was improved and columnar film growth became more dominant as the zinc concentration and the substrate withdrawal speed decreased. The individual layer thickness for layer-by-layer homoepitaxy growth that resulted in columnar grains was <20 nm. The grain columns are grown through the entire film with a nearly unchanged lateral dimension through the full film thickness. The columnar ZnO grains are c -axis oriented perpendicular to the interface and possess a polycrystalline structure. Optical transmittance up to 90% in the visible range and electrical resistivity as low as 6.8 × 10,3·,·cm were obtained under optimal deposition conditions. [source] Nitridation and reoxidation of high- k metal oxide thin films using argon excimer sourcesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2006J. J. Yu Abstract We report for the first time the nitridation and reoxidation of metal oxide films with the active nitrogen and oxygen species produced by argon excimer sources. Preliminary results on 9 nm Ta2O5 films using this method exhibited excellent electrical properties with the leakage current density being up to 3 orders of magnitude lower than the as-deposited films. Breakdown fields were found to be greater than 13 MV/cm. Accumulation capacitance with the nitrided film increased by 25% compared with the as-deposited film. Optical transmittance was as high as 99% in the visible region and more than 74% in the UV region. The refractive index at 632.8 nm was high up to 2.2. The Ar excimer source emitted energetic VUV photons which could break nitrogen triple bonds to produce active nitrogen species and photodissociate O2 to form strong oxidant O3 and highly reactive O (1S) atoms, leading to the nitridation and reoxidation of Ta2O5 without the need for the use of H2O, NH3 and high temperature substrate heating. The nitridation process for a specific film thickness can be optimised by adjusting the VUV irradiation time to achieve increased accumulation capacitance and improved leakage property simultaneously. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication of a n -type ZnO/p -type Cu,Al,O heterojunction diode by sputtering deposition methodsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2009Satoru Takahata Abstract CuAlO2 polycrystalline films were deposited by the helicon-wave-excited plasma sputtering (HWPS) method at 700 °C. The best full-width at half-maximum value of the (006) CuAlO2 X-ray diffraction peak was 0.19 degrees, which was similar to those reported previously using other deposition methods. While, noncrystalline Cu,Al,O films were deposited by a conventional RF sputtering method. Using this p -type transparent conducting oxide (TCO) film and an n -type ZnO film deposited by HWPS, a n -type ZnO/p -type Cu,Al,O heterojunction diode was fabricated. Optical transmittance of the device was approximately 80% in the near infrared region. The rectifying current,voltage characteristics with a threshold forward voltage approximately 1.4 V were obtained. These results are the first step toward realizing an electrical/optical device using p -type CuAlO2 or Cu-Al-O films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Translucent ,-Sialon Ceramics by Hot PressingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2004Xinlu Su The single-phase ,-sialon ceramics with high optical transmittance have been prepared by hot pressing. The maximum transmittance reached 65.2% and 52.2% in the infrared wavelength region, 58.5% and 40% in the visible region for the samples 1.0 and 1.5 mm thickness, respectively. The material also exhibited good mechanical properties of high hardness (20 GPa) and better fracture toughness (5.1 MPa·m1/2). Both high optical transmittance and improved toughness of ,-sialon ceramics were attributed to the less-grain-boundary glassy phase and the homogeneous microstructure, which was obtained by a proper process and confirmed by SEM and TEM observation, compared to that prepared by ordinary sintering. It is, therefore, expected that the translucent ,-sialon ceramics could be a promising optical window material. [source] Aluminum Silicate Films Obtained by Low-Pressure Metal-Organic Chemical Vapor DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003Dong-Hau Kuo Amorphous alumina-silica films with film thickness of 0.41,2.69 ,m were prepared on glass and silicon substrates by metal-organic chemical vapor deposition using a mixture of aluminum tri-sec-butoxide (ATSB), hexamethyldisilazane (HMDSN), and argon. By controlling the inputs of ATSB and HMDSN, alumina-silica thin films could contain varied compositions and adjustable properties. Basically, the codeposition of alumina and silica to form alumina-silica using ATSB and HMDSN had a faster growth rate than their individual components. The internal stress could be adjusted by deposition temperature and reactant inputs. Adhesion could be improved by having a silicon-rich thin film, whereas an aluminum-rich film could have slightly higher hardness. Optical properties, e.g., refractive index and optical transmittance, were also measured. [source] Fabrication of Optically Transparent Lead Lanthanum Zirconate Titanate ((Pb,La)(Zr,Ti)O3) Ceramics by a Three-Stage-Atmosphere-Sintering TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2002Yoshiyuki Abe An easy technique has been developed to fabricate optically transparent lanthanum-modified lead zirconate titanate (PLZT) ceramics. This technique consists of three stages: (1) sintering in an oxygen atmosphere, (2) elimination of pores in a carbon dioxide atmosphere, and (3) elimination of oxygen vacancies in an oxygen atmosphere. The carbon dioxide atmosphere enhances the diffusion of oxygen from the pores to outside the sintered body. The experimental results reveal that use of a carbon dioxide atmosphere effectively decreases residual pores and improves optical transmittance. From commercially available raw powders, an optical transmittance of 51% (wavelength of 550 nm) can be achieved for 0.7 mm thick polished PLZT9/65/35 ceramics using a carbon dioxide atmosphere, whereas the value is only 34% without a carbon dioxide atmosphere. The advantage of this technique is that PLZT ceramics having high optical quality can be obtained using conventional sintering tools. [source] In-situ synthesis of transparent and conductive carbon nanotube networksPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 4 2007Márcio D. Lima Abstract A method for the production of transparent carbon nanotube networks (CNTNs) over transparent substrates was developed. In this method, CNTNs were grown directly in the target surface by applying the catalyst in specific zones of the substrate through lithographic techniques. The networks can be also transferred from the original substrate to other surfaces. The newly grown carbon nanotubes have a very high aspect ratio (>50000). Thus far, networks with an optical transmittance of 94% at 550 nm and a surface resistivity of 3.6 k,/sq have been produced. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optoelectronic properties of transparent p-type semiconductor CuxS thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2010P. Parreira Abstract Nowadays, among the available transparent semiconductors for device use, the great majority (if not all) have n-type conductivity. The fabrication of a transparent p-type semiconductor with good optoelectronic properties (comparable to those of n-type: InOx, ITO, ZnOx or FTO) would significantly broaden the application field of thin films. However, until now no material has yet presented all the required properties. Cu2S is a p-type narrow-band-gap material with an average optical transmittance of about 60% in the visible range for 50,nm thick films. However, due to its high conductivity at room temperature, 10,nm in thickness seems to be appropriate for device use. Cu2S thin films with 10,nm in thickness have an optical visible transmittance of about 85% rendering them as very good candidates for transparent p-type semiconductors. In this work CuxS thin films were deposited on alkali-free (AF) glass by thermal evaporation. The objective was not only the determination of its optoelectronic properties but also the feasibility of an active layer in a p-type thin film transistor. In our CuxS thin films, p-type high conductivity with a total visible transmittance of about 50% have been achieved. [source] Effect of substrate temperature on structural, optical and electrical properties of spray pyrolytically grown nanocrystalline SnO2 thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2007Saji Chacko Abstract SnO2 nanocrystalline thin films were prepared by a spray pyrolysis method on glass substrates at 375, 400, 425, 450 and 500 °C. Structural, optical and electrical properties of these films were studied by X-ray diffraction, UV,visible and four-probe methods. The change in electrical conductivity, band gap and optical transmittance was found to be a function of the change in lattice parameters ,a and ,c The samples prepared at 425 °C are found to have good figure of merit and maximum transmittance (96% at 550 nm). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical properties of delta poly-type quasiregular dielectric structures made of porous siliconPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2007V. Agarwal Abstract To investigate the reflection of light in quasi-regular dielectrics, we study here the optical properties of porous-silicon-based Fibonacci, Thue-Morse and Period Doubling heterostructures. The multilayered systems are fabricated in such a way that each element in the two-block substitutional sequence has a poly-type structure. Both delta-like and traditional configurations are considered. The results for the optical transmittance are analyzed and compared with the classical periodic structure. Numerical simulation for the transmittance along the lines of the transfer matrix approach is also presented. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low temperature growth of transparent conducting ZnO films by plasma assisted depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006A. Nishii Abstract Transparent conducting ZnO films are deposited by plasma assisted deposition technique on glass and plastic substrates at temperatures 60 , 300 °C using metallic Zn, metallic Ga and plasma-excited oxygen as source materials. Deposited films were characterized by X-ray diffraction (XRD), optical transmittance in the visible and infrared region, Raman scattering, and Hall measurements. Film properties are controlled by substrate temperature, oxygen source/zinc source supply ratio, and Ga doping. 350 nm-thick Ga-doped ZnO films deposited at 290 °C showed low resistivity (,2 × 10,4 , cm) and high transmittance in the visible region (,85%). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structural and optical properties of polycrystalline MgxZn1,xO and ZnO:Mn films prepared by chemical spray pyrolysisPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006Tomoaki Terasako Abstract Polycrystalline MgxZn1,xO (0.00 , x , 0.21) and ZnO:Mn films prepared by chemical spray pyrolysis were characterized by X-ray diffraction, optical transmittance, photoacoustic (PA) spectroscopy and photoluminescence (PL). Successful growth of the MgxZn1,xO (0.00 , x , 0.21) films was confirmed by the blue shift of both the near-band-edge PL peak and absorption edge with increasing the alloy composition x. However, the influence of the tail states caused by the deviation from stoichiometric compsosition and/or the spatial fluctuation of the alloy composition x was observed on the PA and PL spectra. Both the transmittance and PA spectra for the ZnO:Mn films showed the absorption band due to the d-d transitions in Mn2+ ion. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Transparent Ohmic Contacts on p-GaN Using an Indium Tin Oxide OverlayerPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003Soo Young Kim Abstract We report a low-resistant, thermally stable ohmic contact on p-GaN using a promising contact scheme of Ni/Au/ITO. Ni/Au contact on p-GaN was annealed at 500 °C under an oxidizing atmosphere before ITO deposition, forming a NiO layer acting as a diffusion barrier of In atoms from ITO. Specific contact resistivity as low as 4.8 × 10,4 ,cm2 was obtained from the Ni (20 Å)/Au (30 Å)/ITO (1000 Å) contact annealed at 500 °C under an oxidizing atmosphere. Contact resistivity is decreased due to crystallization of ITO and Au indiffusion through the NiO layer after annealing at 500 °C under an oxidizing ambient. Also, under this condition, the measured optical transmittance of Ni/Au/ITO was above 80% at a wavelength of 470 nm. [source] Anisotropy in optical transmittance and molecular chain orientation of silver- dispersed uniaxially drawn polyimide filmsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2003Sho-ichi Matsuda Abstract The anisotropy in optical transmittance in the visible and near-infrared region observed for uniaxially drawn and silver-dispersed polyimide (PI) films was investigated. The films were prepared in a one-step operation that consists of thermal curing and simultaneous uniaxial drawing of poly(amic acid) (PAA) films dissolving 5.7,,,20 mol% of silver nitrate. The PAA was converted to PI by heating, and the PI chains were orientated along the drawing direction during curing. Silver nanoparticles were precipitated in the films when they were cured in air and under nitrogen. In particular, silver nanoparticles aggregated along drawing direction and spheroidal nanoparticles (size of longer axis: 10,25,nm, aspect ratio: ca. 1.5) were observed in the films cured in air, and distinct anisotropy in optical transmittance was observed. The maximum optical anisotropy was obtained with a specific holding time at the final curing temperature (320,°C). In addition, the anisotropy can be controlled by polymer chain orientation when films are cured with the optimal holding time. In optimized preparing conditions, anisotropies in transmittance larger than 500,:,1 were obtained at the wavelengths between 700 and 900,nm, and its optical properties were retained after annealing at 150,°C for 1,hr. The PI films thus obtained can be used as thermally stable thin-film polarizers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Thinnest Two-Dimensional Nanomaterial,Graphene for Solar EnergyCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 7 2010Yun Hang Hu Prof. Abstract Graphene is a rapidly rising star in materials science. This two-dimensional material exhibits unique properties, such as low resistance, excellent optical transmittance, and high mechanical and chemical stabilities. These exceptional advantages possess great promise for its potential applications in photovoltaic devices. In this Review, we present the status of graphene research for solar energy with emphasis on solar cells. Firstly, the preparation and properties of graphene are described. Secondly, applications of graphene as transparent conductive electrodes and counter electrodes are presented. Thirdly, graphene-based electron- (or hole) accepting materials for solar energy conversion are evaluated. Fourthly, the promoting effect of graphene on photovoltaic devices and the photocatalytic property of graphene,semiconductor composites are discussed. Finally, the challenges to increase the power conversion efficiency of graphene-based solar cells are explored. [source] An investigation into direct dye aggregationCOLORATION TECHNOLOGY, Issue 1 2002M. Ferus-Comelo The aggregation characteristics of the direct dye CI Yellow 162 have been investigated by measuring the optical transmittance at specific temperatures, in the presence and absence of electrolyte and surfactant, using a Hellma quartz immersion probe attached via fibre optical cables to a single-beam Zeiss Specord S 100 spectrophotometer. The experiments indicate that the dye in solution, without electrolyte, was monomolecular at temperatures of 70 °C and higher. The dye solution with electrolyte remained aggregated at temperatures up to 90 °C, a finding contrary to the still widespread assumption that the dyes are monomolecular at elevated temperatures. In the presence of a surfactant the dye appeared to be forming dye,surfactant micelles that were fairly stable even at higher temperatures. [source] | ||||||||||||||||