FeCuNbSiB非晶粉体/IIR复合薄膜的拉伸及压缩应力阻抗效应

以FeCuNbSiB非晶粉体/IIR复合薄膜材料为研究对象,分别研究了该材料在固定测试频率为1KHz下的拉伸和压缩应力阻抗效应。其中压缩速度为0.01mm/s,压缩最大应力为1MPa;拉伸速度为0.05mm/s,拉伸最大应力为2.4MPa。同时,将2种测试过程在每隔50s时间,计算一个等效的拟合点,并将这些等效拟合点进行曲线拟合,获得相应的拟合曲线。接着我们又对拉伸应力阻抗及压缩应力阻抗等效拟合曲线经行求导处理,得出相应的能够表征应力阻抗的敏感性的函数Z’(σ)。试验结果表明:拉伸过程阻抗随着应力增大而降低,压缩过程阻抗随着应力增大而增大。由于该复合薄膜的基体是丁基橡胶,适合于微小应力敏感的测试。而压缩应力阻抗方面,其耐压强度相对耐拉强度大很多,论文中只讨论了压应力范围为0~1MPa的压应力阻抗效应。在微应力条件下,压应力阻抗敏感性能不及拉伸应力阻抗。而在大应力下其应力敏感特性较好。     

Surface Acoustic Wave Characterization of Equivalent Young's Moduli for Patterned Films北大核心CSCD

Based on the equivalent elasticity theory for layered materials, the micro-mechanics equivalent models for single and dual damascene structures were established. The equivalent elastic constant of the patterned structure was introduced, to establish the propagation model for the surface acoustic waves propagating in the layered structure of the patterned film/ substrate, and the theoretical dispersion curves of the surface acoustic waves were calculated with Green’s function and the matrix method. The finite element method was used to calculate 24 numerical examples of damascene structures with different volume ratios, and the results were compared with those of the strain energy method. The results show that, the average relative errors of the equivalent Young’s moduli of the 300 nm-thick dual damascene film and the 100 nm-thick single damascene film are 2.06% and 2.27%, respectively. The research verifies the correctness of the equivalent patterned structure model and the feasibility of the surface acoustic wave method to characterize the mechanical properties of patterned films, and provides a reference for the development of suitable chemico-mechanical polishing technologies for patterned films under low pressure. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

Optical transmittance spectroscopy of concentric-shell fullerenes layers produced by carbon ion implantation

Concentric-shell fullerenes, also called carbon onions, produced by carbon ion implantation into silver thin films, and subsequently deposited on a silica substrate, were studied by optical transmission spectroscopy in the wavelength range 0.2 - 1.2 μm. In this interval, the strongest absorption is due to the π-plasmon of sp²-like carbon. The position of the plasmon absorption band clearly evolved from 265 nm at low fluence to 230 nm at high implantation fluences. A simulation of the optical spectra based on dielectric models of the concentric-shell fullerenes layer allowed us to identify the first peak as due to disordered graphite and the latter to the carbon onions. The concentration of residual graphite and the filling fraction of the carbon onions produced at high fluences could be estimated by fitting the optical spectra with computed transmittance curves. Received 13 July 2000     

Asymptotic behaviour and general properties of harmonic generation susceptibilities

We use the Kubo response function formalism to derive the asymptotic behaviour of the harmonic generation susceptibilities to all orders n. The results show a stringent correspondence with the ones previously obtained from the classical anharmonic oscillator model. They are characterized by a dependence and a coefficient proportional to the trace of the (n+1)th derivative of the potential energy on the equilibrium density matrix. Using the above results we derive new Kramers-Kr?nig relations and sum rules for all orders of harmonics susceptibilities. Received 17 April 2000     

高增透的类金刚石碳膜的红外吸收特性研究

利用射频等离子体分解甲烷的技术在锗片上沉积了非晶结构的类金刚石碳膜,傅里叶红外光谱仪测量显示镀覆的类金刚石碳膜的锗片在红外范围内具有高增透作用,特别在１７４０～！２０４４ｃｍ＾－１其峰值透过率高达９９％,在９４５．７ｃｍ＾－１（１０．６ｕｍ）处透过率为９４．５％。利用实测的液内的吸收系数接近于０,在１０．６ｕｍ的吸收系数为２３０ｃｍ＾－１,膜主要由ｓｐ＾３的Ｃ＿Ｈ键结构组成,各吸收峰均得到了很好的     

GaAs/SiO2纳米晶镶嵌薄膜的拉曼光谱与吸收光谱研究

采用射频磁控共溅射与高真空退火相结合的方法,分别在单晶硅片和光学石英玻璃片上制备了ＧａＡｓ／ＳｉＯ２纳米晶镶嵌薄膜样品。激光拉曼光谱的测量结果表明,退火态样品（４００℃,６０ｍｉｎ）的拉曼光谱特征峰呈现宽化和红移,红移量为９．５ｃｍ＾－１,对应薄膜中ＧａＡｓ纳米晶粒平均粒径约为３ｎｍ。样品的室浊吸收光谱测量结果表明,由于受量子限域效应的主导作用,与ＧａＡｓ块状单晶相比,样品光学吸收边呈现出明显的蓝     

An improved radio frequency heavy ion source

Abstract

An improved r.f. heavy ion source, which can operate with gases, liquids and solids is described. The operating temperature of the ion source may reach 1000°C. It can therefore, generate ion beams of a considerable number of elements. including metallic ions. At present, ion beams of S⁺, Al⁺, As⁺. Zn⁺, Mg⁺, Cd⁺, Ag⁺, Sm⁺, Te⁺, Se⁺, Sn⁺, In⁺, Hg⁺, etc. have been extracted. The extracted total beam current ranges from several hundred microamperes to the order of milliampere. The useful fraction of ion in the total beam is 70–90%. Life span of the source ranges from 40 hours to more than 100 hours. The emittance of the source is 3 × 10^?6 cm rad. Structure and operating characteristics of this ion source are discussed.     

Enhancing the performance of thin film CdS/PbS photovoltaic solar cells

This work investigates dependence of the short-circuit current density, open-circuit voltage, fill factor and efficiency of a thin film CdS/PbS solar cell on thickness of transparent conductive oxide (TCO) layer, thickness of window layer (CdS), concentration of uncompensated acceptors (width of space-charge region), carrier lifetime in PbS and the reflectivity from metallic back contact. The effect of optical losses, front and rear recombination losses as well as the recombination losses on space-charge region are also considered in this study. As a result, by thinning the front contact layer indium tin oxide from 400 to 100 nm and window layer (CdS) from 200 to 100 nm it is possible to reduce the optical losses from 32 to 20%. The effect of electron lifetime on the internal and external quantum efficiency can be neglected at high width of the space-charge region. The maximum current density of 18.4 mA/cm² is achieved at wide space-charge region (concentration of uncompensated acceptors = 10¹⁵ cm^?3) and the longest lifetime (τ_n = 10^?6 s) where the optical and recombination losses are about 55%. The maximum efficiency of 5.17%, maximum open-circuit voltage of 417 mV and approximately fixed fill factor of 74% are yielded at optimum conditions such as: electron lifetime = 10^?6 s; concentration of uncompensated acceptors = 10¹⁶ cm^?3; thickness of TCO = 100 nm; thickness of CdS = 100 nm; velocity of surface and rear recombination = 10⁷ cm/s and thickness of absorber layer = 3 μm. When the reflectance from the back contact is 100%, the cell parameters improve and the cell efficiency records a value of 6.1% under the above conditions.     

脉冲高能量密度等离子体薄膜制备与材料表面改性

脉冲高能量密度等离子体是一项全新的等离子体材料表面处理和薄膜制备技术。文章主要介绍了作者近几年来在这方面的研究成果。从理论和试验上研究了脉冲高能量密度等离子体的产生机制及其物理性质，研究了脉冲等离子体与材料相互作用的基本物理现象和物理机制，诊断测量表明，脉冲等离子体具有电子温度高（10－100eV）、等离子体密度高（10^14-10^16cm^-3）、定向速度高（－10^7cm/s）、功率大（10^4W/cm^2）等特点，在制备薄膜时具有沉积速率高，薄膜与基底粘结力强，并兼有激光表面处理、电子束处理、冲击波轰击、离子注入、溅射、化学气相沉积等综合性特点，可以在室温下合成亚稳态相和其他化合物材料。在此基础上，系统地进行了脉冲等离子体薄膜制备和材料表面改性及其机理的研究，在室温下的不同材料衬底上成功的沉积了性能良好的较大颗粒立方氮化硼、碳氮化钛、氮化钛、类金刚石、氮化铝等薄膜材料，沉积薄膜和基底之间存在一个很宽的过渡层，因此导致薄膜与基底有很强的粘结力，经脉冲等离子体处理过的金属材料表面性能得到了极大改善。     

Physics of transparent conductors

Transparent conductors (TCs) are materials, which are characterized by high transmission of light and simultaneously very high electrical DC conductivity. These materials play a crucial role, and made possible numerous applications in the fields of electro-optics, plasmonics, biosensing, medicine, and “green energy”. Modern applications, for example in the field of touchscreen and flexible displays, require that TCs are also mechanically strong and flexible. TC can be broadly classified into two categories: uniform and non-uniform TC. The uniform TC can be viewed as conventional metals (or electron plasmas) with plasma frequency located in the infrared frequency range (e.g. transparent conducting oxides), or ultra-thin metals with large plasma frequency (e.g. graphen). The physics of the nonuniform TC is much more complex, and could involve transmission enhancement due to refraction (including plasmonic), and exotic effects of electron transport, including percolation and fractal effects. This review ties the TC performance to the underlying physical phenomena. We begin with the theoretical basis for studying the various phenomena encountered in TC. Next, we consider the uniform TC, and discuss first the conventional conducting oxides (such as indium tin oxide), reviewing advantages and limitations of these classic uniform electron plasmas. Next, we discuss the potential of single- and multiple-layer graphene as uniform TC. In the part of the paper dealing with non-uniform metallic films, we begin with the review of random metallic networks. The transparency of these networks could be enhanced beyond the classical shading limit by the plasmonic refractive effects. The electrical conduction strongly depends on the network type, and we review first networks made of individual metallic nanowires, where conductivity depends on the inter-wire contact, and the percolation effects. Next, we review the uniform metallic film networks, which are free of the percolation effects and contact problems. In applications that require high-quality electric contact of a TC to an active substrate (such as LED or solar cells), the network performance can be optimized by employing a quasi-fractal structure of the network. We also consider the periodic metallic networks, where active plasmonic refraction leads to the phenomenon of the extraordinary optical transmission. We review the relevant literature on this topic, and demonstrate networks, which take advantage of this strategy (the bio-inspired leaf venation (LV) network, hybrid networks, etc.). Finally, we review “smart” TCs, with an added functionality, such as light interference, metamaterial effects, built-in semiconductors, and their junctions.