An iterative method for calculating the shielding effectiveness andlight transmittance of multilayered media

A simple, rapid, and accurate numerical method is presented for calculating the shielding effectiveness and the light transmittance of multilayered media. A uniform treatment is used to obtain the shielding effectiveness of the layers at microwave frequencies and their light transmittance at optical frequencies. The method is completely general and does not involve any approximation. It can be applied at any frequency, for vertical or oblique incidence, to lossless or lossy, isotropic or anisotropic media consisting of any number of dielectric and metallic layers. In order to illustrate the versatility of the method, the shielding effectiveness and the light transmittance of two different structures consisting of a gold film deposited over a plastic substrate and of a plastic substrate sandwiched between two gold films are analyzed under different conditions     

Light Transmittance and RF Shielding Effectiveness of a Gold Film on a Glass Substrate

Light transmittance and the Rf shielding effectiveness of a gold film on a glass substrate is investigated. The dependence of the transmittance of visible light upon the thickness or surface resistance of a gold film on a glass substrate is determined numerically by the optical properties of the gold film and glass substrate. The Rf shielding effectiveness produced in the far field over the frequency range of 100 MHz to 30 GHz by the gold film is calculated and compared with experimental data. An optimum condition is established between the light transmittance and the shielding effectiveness. The results are applicable to any transparent glass coated with any thin metallic film.     

Light Transmittance and Microwave Attenuation of a Gold-Film Coating on a Plastic Substrate (Short Papers)

Light transmittance and microwave attenuation of a gold-film coating on a plastic substrate is investigated. The dependence of the transmittance of visible light upon the thickness or resistivity of a gold-film coating on a plastic substrate is analyzed numerically. The microwave attenuation produced in the far field over the frequency range of 100 MHz-30 GHz by the gold film is calculated and compared with experimental data. An optimum condition is established between the light transmittance and the microwave attenuation. The results are applicable to any transparent glass coated with any thin metallic film.     

Nanolayered lightweight flexible shields with multidirectional optical transparency

New nanolayered coatings are designed and deposited on flexible plastic substrate having the thickness of 100 /spl mu/m, in order to realize lightweight ultrathin transparent shielding foils. The structure of the coating is optimized considering three figures of merit: the average transmittance in the visible range for normal incidence, the normalized average transmittance for oblique incidence at 550 nm, and the transmittance quality factor. The nanotechnology exploited for the deposition of the transparent metals is the dual ion beam sputtering. Tests of durability, optical transmission, and shielding effectiveness demonstrate that the film has a high adhesion under mechanical solicitation, high resistance against aging, peak transmittance in the visible range higher than 70%, omnidirectional properties in the range 0/spl deg/-60/spl deg/, and shielding effectiveness of 40 dB up to 6 GHz.     

电镀废液回收铜粉的化学镀银工艺及其电磁屏蔽性能

采用高频超声脉冲电解法从电镀铜废液中回收制备枝晶状的铜粉,并在铜粉表面进行化学镀银以制备电磁屏蔽用银包铜粉,采用SEM、EDS、XRD、TEM等对其进行形貌和组分分析,研究了银包铜粉复合涂层的导电性能和电磁屏蔽性能。结果表明,经过表面化学镀银可以有效地避免铜粉的氧化;涂层的电磁屏蔽性能与银包铜粉的添加量紧密相关,当涂层中银包铜粉质量分数为60%时,其电磁屏蔽效率高达52 dB。     

Nanotechnology of transparent metals for radio frequency electromagnetic shielding

The aim of this paper is to present an innovative one-dimensional photonic bandgap structure on plastic substrate, for electromagnetic field shielding applications in the radio frequency range. A complete study is performed, from material characterization and design, to fabrication and experimental test of a prototype sample consisting of seven alternating zinc oxide and silver (Ag) layers, on Lexan polycarbonate. The transparent metal is designed to obtain high shielding effectiveness (SE), not just as a theoretical prediction, but as experimentally measured according to the standard ASTM-D 4935/89. Actually, the shielding performance of multilayered coatings having similar values of sheet resistance but different design are strongly affected by the bonding conditions. The following properties of the structure, which contains only 66 nm of Ag, are highlighted: 1) it remains transparent in the visible range; 2) it retains the conductivity of bulk metal; 3) it has SE in the 30-kHz to 1-GHz range over 40 dB; 4) the overall thickness of the multilayer shielding coating is 312 nm; and 5) it has been realized on both glass or plastic substrate.     

金属网栅电磁屏蔽窗口薄膜的设计与制备

通过光刻掩膜技术、电阻热蒸发沉积技术制备电磁屏蔽窗口金属网栅薄膜,研究金属网栅的红外透射率和电磁屏蔽效能。为了能有效地屏蔽电磁波,使用CST Studio Suite电磁仿真软件设计不同周期、线宽的金属网栅,采用光刻掩膜技术、电阻热蒸发技术在双面抛光单晶硅基片上完成线宽为30μm,周期分别为350μm、450μm、550μm、650μm、750μm的金属网栅薄膜的制备。采用真空型傅立叶红外光谱仪和矢量网络分析仪分别对不同结构参数金属网栅薄膜的光谱特性和电磁屏蔽效能进行测试。结果:实现在双面抛光单晶硅基底上制备的网栅在12~18 GHz频段内,网栅的电磁屏蔽效能均达到12 dB以上。在3~5μm波段的透射率损失仅为8%。为了得到既具有高透光率,又具有强电磁屏蔽效能金属网栅薄膜需要合理设计金属网栅的线宽和周期。制备过程中网栅的光学-电学特性不仅受周期和线宽影响,掩膜板的加工精度、金属网栅的加工缺陷等也会造成不同程度的影响。     

Effect of Colloidal Silver on Optical Transmittance Characteristics of Bulk Cadmium Zinc Telluride Crystals

Colloidal silver is observed to affect the transmittance of p-type Cd_1−y Zn _y Te (CZT) single-crystal substrate material at room temperature. The optical transmittance spectra have been analyzed in the near-infrared (NIR) and mid-infrared (MIR) regions. The transmittance characteristics of CZT showed significant reduction in absorption due to split-off valance band transitions in the NIR region and intervalence band absorption in the MIR region upon coating CZT substrates with silver paste. This reduction in absorption has been explained to be due to the compensation of the acceptor defects (native and foreign). Silver atoms incorporated from the silver coating help in compensation of these defects. A similar effect on transmittance characteristics of mercury cadmium telluride (MCT) epilayers grown on CZT substrates after coating silver paste on the CZT substrate side was also observed. An improvement in the transmittance of CZT substrates after the application of silver paste was observed. A similar improvement in transmittance is usually achieved by annealing the substrates in a Cd/Zn atmosphere. The results are explained by considering the formation of neutral complexes of acceptors (cadmium vacancies) and the interstitial silver. This study also points to the important conclusion that silver paste on CZT should be applied with caution for measurement purposes since it diffuses even at room temperature and modifies the optical characteristics.     

A highly conductive and smooth AgNW/PEDOT:PSS film treated by hot-pressing as electrode for organic light emitting diode

A highly conductive, smooth and transparent electrode is developed by coating poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) over silver nanowires (AgNWs) followed by a hot-pressing method. The hot-pressed AgNW/PEDOT:PSS film shows a low sheet resistance of 12 Ω/square, a transmittance of 83% at 550 nm and a smooth surface. The improvement of the conductivity and smoothness are ascribed to the fusion of nanowires resulted from the mechanical hot-pressing. The AgNW/PEDOT:PSS film on polyethylene naphthalate (PEN) substrate exhibits higher conductive stability against the bending test than commonly used indium tin oxide (ITO). Using the hot-pressed AgNW/PEDOT:PSS film as the anode, we have fabricated ITO-free organic light emitting diode with a maximum current efficiency of 58.2 cd/A, which is higher than the device with ITO anode. This proves that such AgNW/PEDOT:PSS film treated by hot-pressing is a promising candidate for flexible optoelectronic devices.     

Ultra-violet direct patterning of metal on polyimide

Copper micro-patterns have been fabricated on polyimide substrates by ultra-violet (UV) lithography without the use of evaporation techniques or photoresist materials. Using a photoreactive polymer-reducing agent, methoxy poly(ethylene glycol) (MPEG) as a thin film coating, a novel light-directed metal-patterning method in air atmosphere was realised. The interaction of UV light and MPEG in ethanol film enabled the photoreduction of mobile silver ions available within the surface-modified polyimide substrates. The silver nanoparticle patterns thus formed served as active catalytic seed layers for subsequent electroless copper plating. Narrow copper tracks with low resistivity close to that of bulk copper were achieved. MPEG is a nontoxic, low cost and commercially available polymer which can be easily spin-coated and washed off after the patterning process. These attractive properties of MPEG together with its photoreactivity provide great potential for developments of UV direct-metallisation methods.     

磁控溅射ZnO基TFT的研究

采用直流磁控溅射在SiO2/n-Si(111)衬底上沉积了Al薄膜,经过光刻、刻蚀形成源漏极,再采用射频磁控溅射沉积ZnO薄膜作为有源层,成功制备了底栅顶接触结构的ZnO-TFT,Al膜厚135nm,ZnO膜厚110nm.实验结果表明,薄膜晶体管展示出明显的栅控特性以及饱和特性,ZnO薄膜沿C轴择优取向生长,且在可见光...     

Bendable Solar Cells from Stable,Flexible, and Transparent Conducting Electrodes Fabricated Using a Nitrogen‐Doped Ultrathin Copper Film

Copper has attracted significant interests as an abundant and low‐cost alternative material for flexible transparent conducting electrodes (FTCEs). However, Cu‐based FTCEs still present unsolved technical issues, such as their inferior light transmittance and oxidation durability compared to conventional indium tin oxide (ITO) and silver metal electrodes. This study reports a novel technique for fabricating highly efficient FTCEs composed of a copper ultrathin film sandwiched between zinc oxides, with enhanced transparency and antioxidation performances. A completely continuous and smooth copper ultrathin film is fabricated by a simple room‐temperature reactive sputtering process involving controlled nitrogen doping (<1%) due to a dramatic improvement in the wettability of copper on zinc oxide surfaces. The electrode based on the nitrogen‐doped copper film exhibits an optimized average transmittance of 84% over a spectral range of 380 ?1000 nm and a sheet resistance lower than 20 Ω sq^?1, with no electrical degradation after exposure to strong oxidation conditions for 760 h. Remarkably, a flexible organic solar cell based on the present Cu‐based FTCE achieves a power conversion efficiency of 7.1%, clearly exceeding that (6.6%) of solar cells utilizing the conventional ITO film, and this excellent performance is maintained even in almost completely bent configurations.     

沃拉斯顿棱镜可见光区减反射膜研制

为了提高镀膜材料和冰洲石基底的附着力以及提高棱镜的透过比,拓宽有效使用带宽,借助于计算机辅助设计方法,设计了高性能多层减反射膜系;选用合适的光学薄膜材料,利用电子束蒸镀,借助于离子源辅助蒸镀,制作了高性能的宽带减反射膜．测试结果表明：e光,o光的平均剩余反射率小于0．5％,有效使用带宽覆盖可见光区;为了改善薄膜和基底问的附着力,采用Al2O3做过渡层。     

ZnO:Al(ZAO)透明导电薄膜的制备及其特性

笔者采用射频磁控溅射工艺、以氧化锌铝陶瓷靶为靶材制备透明导电ZAO薄膜,系统研究了各工艺参数,如氧流量、工作气压、温度、射频功率和退火条件等对其结构和光电特性的影响。实验结果表明:在纯氩气中且衬底温度为300℃时制备的ZAO薄膜经热处理后电阻率降至8.7104 W·cm,可见光透过率在85%以上。X射线衍射谱表明ZAO晶粒具有六角纤锌矿结构且呈c轴择优取向,晶粒垂直于衬底方向柱状生长。     

Properties of ZnO/Cu/ZnO multilayer films deposited by simultaneous RF and DC magnetron sputtering at different substrate temperatures

ZnO/Cu/ZnO transparent conductive multilayer films are prepared by simultaneous RF sputtering of ZnO and DC sputtering of Cu. The properties of the multilayer films are studied at different substrate temperatures. Sheet resistance of the multilayer film decreased initially with increase of substrate temperature and increased further with increase of substrate temperature beyond 100 °C. However, transmittance of the multilayer film increased with increase of substrate temperature. Good transparent conductive film of sheet resistance 9.3 Ω/sq and transmittance of 85% was found at a substrate temperature of 100 °C. The performance of the multilayer film was evaluated using a figure of merit. The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.     

高耐温精密冷反光镜研制

高耐温精密冷反光镜是应用于影像光学系统的一种常用光学元件,它具有高耐温性、反射可见光、透射红外光的特点。本文介绍了采用低膨胀系数的高耐温性基底材料,利用电子束热蒸发物理气相沉积镀膜方法及离子辅助沉积工艺,制备出了可见光光谱平均反射率高于95%、红外光光谱平均透过率高于85%,膜层耐温性能达到450℃高温下膜层无异常的反光镜产品,并实现了批量生产。     

射频磁控溅射制备非晶WO3薄膜的结构及其光电性质研究

采用射频磁控溅射技术,以WO3陶瓷靶为原料,在透明导电氧化铟锡（ITO）玻璃上沉积了非晶相WO3薄膜,研究了溅射功率对薄膜结构及光学性质的影响,并研究了WO3薄膜的电致变色特性。利用扫描电子显微镜（SEM）、X射线衍射技术（XRD）表征了薄膜的表面形貌和内部结构;利用UV-Vis分光光度计表征了薄膜在变色前后的光学透过性质,利用电化学测试工作站研究了WO3薄膜的电致变色性质,并从原理上分析了WO3薄膜的变色机理。研究结果表明,不同功率下获得的WO3薄膜均为非晶结构,在可见光范围内有较高的透过率。透明的WO3薄膜在负向电压下逐渐转变成深蓝色,且在撤去电压后其颜色不变,当施加正向电压时,薄膜又转换为透明态,表现出良好的电致变色特性。所制备WO3薄膜在550nm处褪色态的透过率为83%,着色态的透过率为29%,使得该薄膜在智能窗方面具有广阔的应用前景。     

Electroless plating of copper on AZ31 magnesium alloy substrates

Chemical surface preparation for copper film on magnesium alloy by both electroless plating and organic coatings was studied. Organic coating was made by immersing the samples into an organosilicon heat-resisting varnish. A subsequent metallization process verified the applicability of this method. In this method, the organic coating acted as an interlayer between the substrate and copper film. When the reaction started, copper deposited directly onto the interlayer surface. X-ray diffraction and SEM analysis were used to understand the composition and morphology of the interlayer and copper film. The copper film has a rather perfect crystalline structure. And the result of the cross-cut test indicates the adhesion between the substrate is good enough. The potentiodynamic polarization curves for corrosion studies of coated magnesium alloys were performed in a corrosive environment of 3.5 wt% NaCl at neutral pH 7. The result reveals that compared with the substrate, the corrosion resistance of the coated AZ31 magnesium alloys increases distinctly. Moreover, the copper film has perfectly antibacterial and decorative properties. The method proposed in this work is environmentally friendly: non-toxic chemicals are used. In addition, this provides a new concept for plating the metals, which are considered difficult to plate due to high reactivity.     

Porous Polymer Films with Gradient‐Refractive‐Index Structure for Broadband and Omnidirectional Antireflection Coatings

Porous polymer films that can be employed for broadband and omnidirectional antireflection coatings are successfully shown. These films form a gradient‐refractive‐index structure and are achieved by spin‐coating the solution of a polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA)/PMMA blend onto an octadecyltrichlorosilane (OTS)‐modified glass substrate. Thus, a gradient distribution of PMMA domains in the vertical direction of the entire microphase‐separated film is obtained. After those PMMA domains are removed, a PS porous structure with an excellent gradient porosity ratio in the vertical direction of the film is formed. Glass substrates coated with such porous polymer film exhibit both broadband and omnidirectional antireflection properties because the refractive index increases gradually from the top to the bottom of the film. An excellent transmittance of >97% for both visible and near‐infrared (NIR) light is achieved in these gradient‐refractive‐index structures. When the incident angle is increased, the total transmittance for three different incident angles is improved dramatically. Meanwhile, the film possesses a color reproduction character in the visible light range.     

All-printed low-voltage organic transistors

All-printed low-voltage organic transistors were manufactured on a plastic substrate and measured in normal room atmosphere. All electrodes were ink-jet printed, while the homogeneous semiconductor and insulator layers were subsequently applied by the reverse gravure coating technique. No destructive effects from the rough plastic substrate or the printed silver source and drain electrodes were observed. Changes in the transistor characteristics after 48 days of ageing in room atmosphere were mainly attributed to a reduced conductivity of the polymer gate electrode.