Optimising the blocking efficiency in shaped Cassegrain systems

The blocking efficiency of a Cassegrain antenna system can be improved considerably by shaping the main and the subreflector in such a way that the power, which is normally lost by scattering against the blocking obstacles, arrives at the aperture in the correct phase and direction and with the correct amplitude. It is explained that shadows of (nearly) spherical waves on the aperture can be made to disappear entirely. A practical example is described.     

金属光栅提高蓝光LED提取效率的研究

为了提高发光二极管(LED)的光提取效率，并比较不同光栅形状对LED光提取效率的影响，采用严格耦合波法优化了与矩形、等腰三角形、等腰梯形光栅分别集成的倒装LED，使它们出光面透射率达到最优，随后使用有限时域差分法模拟计算它们的光提取效率。经过模拟计算和理论分析可得3种不同结构LED最优光栅参量(光栅占空比f、光栅周期p、光栅厚度h)和过渡层厚度d分别是:f=0.35, p=150nm, h=80nm, d=190nm; f=0.45, p=175nm, h=80nm, d=190nm; f=0.7, p=150nm, h=80nm, d=190nm。结果表明，3种最优的LED结构在波长0.4μm~0.5μm范围内，矩形光栅倒装LED和等腰三角形光栅倒装LED出光面透射率相同，等腰梯形光栅倒装LED出光面透射率最低; 由于光透射率最低，导致等腰梯形光栅倒装LED光提取效率较低，最高仅为58.07%，但是由于等腰三角形光栅倒装LED特殊的光栅形状加上高的光透射率，其光提取效率可以达到77.75%。此研究可以为制备高光提取效率LED提供理论方法指导。     

金属氧化物改性炭电极及EDLC性能研究

将市售活性炭用Ni(NO3)2及Co(NO3)2溶液浸渍后进行高温热解处理。采用BET、循环伏安、恒流充放电等测试手段,研究改性活性炭电极构成的双电层电容器(EDLC)性能。结果表明,由Ni(NO3)2及Co(NO3)2热解产生的NiO、CoO有显著的准电容效应,与活性炭原有的双电层电容构成了复合电容,因而改性炭的电容量有明显提高,质量比电容分别高达246.1,198.8 F/g,比原样炭的130.1 F/g分别提高了89.2%、52.8%。     

利用金属光栅提高LED发光效率的研究

为了提高发光二极管(LED)的发光效率,在LED出光面放置金属光栅,采用时域有限差分法进行了理论分析和模拟计算.结果表明,对光栅优化后,金属光栅对波长460nm的透射率接近1,可提高LED的光提取效率;在此波长下,可同时激发局域表面等离激元和表面等离极化激元,有助于提高LED内量子效率;且具有金属光栅结构的LED的发光...     

First principles study of Nb-W bilayer metal gate electrode

First principles calculations are performed to study the electronic structure and related properties of the Nb-W interface within NbW multilayer metal gate electrode. It is found that the surface work functions of NbW multilayers are located between those of pure Nb and W surfaces due to the strain effect from the lattice dismatch. The interface energy of Nb(1 1 0)/W(1 1 0) is calculated to be −0.17 J/m², implying that the Nb-W interface is energetically favorable. Additionally, it is found that the interface dipoles are formed in the interface region to balance the work function difference of W and Nb, and the dipole layers are mainly due to the contributions of interface atoms with a very small contribution from the second atomic layers from the interface. It is of interest to note that the interface W atoms give out a little bit more electrons than the interface Nb atoms during the formation of the interface dipole and that these changes are closely related to the DOS changes.     

关于三极场发射显示器样机中夹心式层状阴极电极的制作研究

Based on an effective screen-printing process,a novel sandwich layered cathode electrode was developed on a cathode faceplate.The ZnO electrode was sandwiched between an indium tin oxide(ITO) electrode layer and a silver electrode layer,and the carbon nanotube was prepared directly on the exposed ITO electrode layer surface.The cathode potential could be conducted to the carbon nanotube with the sandwich layered cathode electrode.Using the carbon nanotube as a field emitter,a triode field emission display prototype with a sandwich layered cathode electrode was fabricated,which possessed a better field emission characteristic,higher luminous brightness and better emission image luminance uniformity.The turn-on electric field was 1.88 V/μm and the measured maximum field emission current was 2273.6μA at 3.19 V/μm.By the method of adjusting the field emission current,the electron-emitting uniform capacity of the carbon nanotube cold cathode could be modified, and the emission image luminance uniformity and the emission current stability of triode field emission display prototype was also be improved significantly.The emission current fluctuation of the sandwich layered cathode electrode type field emission display was less than 1.1%.Furthermore,the total manufacture cost of the triode field emission display prototype was low.     

Diffraction efficiency and guided light control by two-dimensionalphotonic-bandgap lattices

We report on the measurement of the diffraction efficiency of two-dimensional photonic-bandgap lattices consisting of a triangular array of circular air holes etched in a semiconductor waveguide. We use the spontaneous emission of the material as an internal point source. Combined with previous reflectivity and transmission measurements, the diffraction data allow us to assess the total amount of out-of-plane losses experienced by a guided wave traversing the dielectric lattice, as a function of the lattice pitch. We found that these losses are particularly weak for some range of parameters, especially in the photonic bandgap of interest. We discuss the reasons why they can be substantial with other parameters     

六硼化镧空心阴极加热效率研究

为研究热屏蔽层对六硼化镧空心阴极加热效率的影响,建立了理论模型进行热力学计算,并通过实验对计算结论加以验证。结果证明,热屏蔽层的应用能够有效地反射热辐射,减少热能散失,降低加热功率,提高空心阴极加热效率,加热效率提高约17%。     

Quantum efficiency of flourescence excited by photodissociation in metal halide vapors and applications

Interaction of ultraviolet radiation with diatomic and triatomic metal halide vapors is discussed. Patterns observed in ultraviolet absorption cross sections are noted. Measurements of quantum efficiency of fluorescence excited by photodissociation (QE = fluorescence photons out/ultraviolet photons in) are described. Results and their implications for 205 ± 15-nm deuterium, 213.9-nm-Zn resonance and deuterium VUV excitation are discussed. Applications of photodissociation in photodissociation lasers, electric discharge lamps, and collisional processes such as measurement of reactive and quenching cross sections are summarized.     

Data transmission efficiency over CDMA systems employing RLP and FEC error control strategies on the radio link layer

In this article, the normalized throughput and the normalized average delay for the transport layer at the reverse link of multicellular CDMA systems are obtained. For the transport layer the Transport Control Protocol (TCP) with consecutive retransmissions control is employed. On the radio link layer three TCP error control strategies are evaluated and compared. The first strategy is based on the radio-link-protocol (RLP), which breaks down the TCP packets into smaller blocks and uses an error detecting procedure to protect those RLP blocks. The second strategy uses forward-error-control (FEC) procedure at the radio link layer. In this case, two kinds of FEC are compared: convolutional and turbo coding. The third one is a hybrid between the first and second strategies with coding at the RLP layer. A frequency-selective Rayleigh fading channel with shadowing and power control loop error is considered.     

Effects of exciton blocking layer and cathode electrode work function on the performance of polymer solar cells

In this study the effects of some important processing and post-processing treatments on the performance of poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C₆₁-butyric acid methyl ester ([60]PCBM) solar cells were investigated. These parameters included the active layer film formation period, thermal annealing, electrical treatment, cathode work function modification, and exciton blocking layer type and thickness. Polymer bulk heterojunction solar cells having a glass/indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/P3HT:PCBM/(Ca or LiF)/Al structure were fabricated. The morphology of the active layer was investigated using atomic force microscopy. The results showed that the morphology state of the active layer exactly after spin coating process was very important parameter, which could dictate different responses of solar cells to a certain treatment. Using solvent additives to prolong the film formation period and storing in small dish could reach the morphology of the active layer near its best state in which there was no need to apply common post-treatment processes. A thickness at about 20 nm was required for Ca layer to effectively act as exciton blocking layer while LiF with 1 nm thickness worked better.     

Run by run advanced process control of metal sputter deposition

Metal sputter deposition processes for semiconductor manufacturing are characterized by a decrease in deposition rate from run to run as the sputter target degrades. The goal is to maintain a desired deposition thickness from wafer to wafer and lot to lot. Run by run (RbR) model-based process control (MBPC) has been applied to metal sputter deposition processes at Texas Instruments. RbR MBPC, based on the exponentially weighted moving-average filter, provides the ability to track and compensate for process drifts without a priori assumptions on their magnitude or consistency (from sputter target to sputter target or collimator to collimator). The application of RbR MBPC resulted in an improved C_pk of 44% for aluminum sputter deposition, while reducing the number of lot-based monitor wafers by a factor of three. The application of RbR MBPC to the titanium sputter deposition process eliminated look-ahead test runs and reduced the number of monitor wafers by a factor of three. At the same time, C_pk was improved by 10% with the application of RbR MBPC     

(中国微米纳米)一种牺牲层工艺中金属电极保护方法研究

为了在牺牲层工艺中保护金属电极不被腐蚀,提出了一种利用铝层保护金属电极的方法。在试验中采用了两种铝保护层厚度300nm和1μm,在两种腐蚀液体4NH4F:1HF:2甘油和1HAC: 1NH4F中进行了试验,通过试验表明,铝金属层在两种腐蚀液体中都能够有效保护金属电极,延长牺牲层的腐蚀时间。最后,通过SOI微加速度计加工工艺进一步验证了该方法的有效性。     

Lithography-independent and large scale fabrication of a metal electrode nanogap

ture was achieved. The size of the nanogap is not determined by the photolithography, but by the thickness of the SiO2. The method reported in this paper is compatible with modern semiconductor technology and can be used in mass production.     

大面积非光刻纳米电极间隙的制备

A lithography-independent and wafer scale method to fabricate a metal nanogap structure is demonstrated. Polysilicon was first dry etched using photoresist （PR） as the etch mask patterned by photolithography. Then, by depositing conformal SiO2 on the polysilicon pattern, etching back SiO2 anisotropically in the perpendicular direction and removing the polysilicon with KOH, a sacrificial SiO2 spacer was obtained. Finally, after metal evaporation and lifting-off of the SiO2 spacer, an 82 nm metal-gap structure was achieved. The size of the nanogap is not determined by the photolithography, but by the thickness of the SiO2. The method reported in this paper is compatible with modern semiconductor technology and can be used in mass production.     

BME MLCC中陶瓷-金属界面行为的研究

针对BME MLCC中陶瓷-金属界面扩散行为,采用SEM、HRTEM、EDS等手段,对MLCC样品的显微结构,陶瓷介质层和镍电极层中的物相进行了表征,给出了各扩散元素的成分分布。结果表明,在BME MLCC的陶瓷-金属界面处存在一定程度的元素扩散,其中Ni元素向陶瓷介质层的扩散较为显著,并导致了钙钛矿结构的晶格畸变。     

机场管制运行效率提升策略研究

近年来,我国经济持续发展。随着经济的发展,民航作为一种重要的交通运输方式在人们生活中的重要性愈发明显。人们对民航发展的关注度持续提升。所以,机场管制运行效率的提升势在必行。文章主要从机场管制运行的现状以及运行效率提升策略方面展开分析。     

Nucleation and control of departure of a high-field domain by a gate electrode

Experimental results are given which show that, in a m.i.s.f.e.t. type GaAs bulk device, a negative voltage applied to the gate electrode can nucleate a high-field domain under the gate electrode, but that its subsequent departure for the anode is allowed or inhibited depending on the device structure and operating conditions.     

Coupling efficiency control of vertically coupled microring resonator filter by microactuator

Coupling efficiency control of vertically coupled microring resonator was successfully realized by microactuator, which is suitable for the simultaneous integration of microelectromechanical systems switch and thermooptic tunable filter. The extinction ratio of drop port response of 15.1 dB, through port response of 2.1 dB, and switching time of 60 /spl mu/s were demonstrated at the applied voltage of 350 V. The loss of through port response in the off-state was reduced to 0.8 dB.