ECR-CVD制备氟化非晶碳低k介质薄膜

采用电子回旋共振等离子体化学气相沉积(ECR-CVD)方法,以C4F8和CH4为源气体在不同气体流量比R(R=[CH4]/{[CH4] [C4F8]})条件下成功地沉积了氟化非晶碳(a-C:F)低介电常数(低k)材料.采用X光电子能谱和椭圆光谱方法分析了a-C:F薄膜的化学组分和光学性质.沉积的a-C:F薄膜介电常数约为2.1～2.4,热稳定性优于350℃.随着气体流量比的增大,沉积a-C:F薄膜中的碳含量增大,CF、CF2、CF3含量减少,C-C交链成分增加,从而使得π-π(*)吸收增强,并引起薄膜光学带隙下降.氮气气氛下350℃温度退火后应力释放引起a-C:F薄膜厚度变化,变化量小于4%.450℃温度退火后,由于热分解作用薄膜厚度变化量在30%左右.     

化学水浴沉积时间对CdS薄膜性质的影响

采用CBD法在醋酸镉溶液体系中制备CdS半导体薄膜,通过XRD、XRF、SEM和光学透过率谱等测试手段研究了沉积时间对CdS薄膜沉积过程和性质的影响.结果表明,随着沉积时间的增加,薄膜增厚;S/Cd原子比增加,但都为富Cd的CdS薄膜;XRD研究表明,薄膜结构由立方、六方混合相向立方相转变,(111)方向成为择优生长方向;SEM研究表明,随沉积时间增加,薄膜变致密,薄膜表面出现的白色附着颗粒增多,尺寸增大;沉积时间对薄膜的光学性质也有很大的影响,随着沉积时间的增加薄膜透过率减小,而禁带宽度值增大.     

Ge1-xCx薄膜的制备及红外特性的研究

利用等离子体化学气相沉积(PECVD)法制备出Ge1-xCx薄膜,并系统地研究了工艺参数对薄膜成分的影响,以及不同组分Ge1-xCx薄膜的红外光学特性.结果表明,薄膜中的C含量随着CH4/GeH4气体流量比的增大而增大;薄膜的红外折射率随组分的不同在2～4范围内变化;薄膜的沉积速率随射频功率增大而增大,但当功率达到60 W以后其变化不明显;沉积速率随温度的增加而减少;该薄膜具有透长波红外的性能.     

氢稀释比对氢化硅薄膜两相结构和电学性能的影响

通过改变氢气对硅烷的稀释比R, 采用等离子体增强化学气相沉积(PECVD)方法制备出具有非晶/微晶相变过渡区的氢化硅薄膜, 并研究了所得硅膜在不同沉积阶段的微观结构和形貌、晶化效果和电学性能。研究结果表明, 当R=10时, 样品呈典型的非晶特性; 随着氢稀释比的增大, 薄膜表现出两相结构, 且衬底表面处的非晶过渡层逐渐减薄, 也即非晶向微晶的转变提前。但XRD结果显示, 硅膜的晶化率和平均晶粒尺寸随着R的增加呈先增后减的趋势, 在R=28.6时达到最大值。另外, 暗电导率和载流子浓度表现出了与晶化率一样的变化趋势, 显示出硅膜的电学性能与微观结构的高度正相关性。     

氢化碳化硅(SixC1-x∶H)薄膜发光特性和纳米线发光增强研究

氢化碳化硅薄膜作为一种宽带隙的半导体材料,具有优越的物理特性,其在光电子器件上的潜在应用引起了人们的兴趣。利用等离子增强化学气相沉积(PECVD)系统制备了一系列氢化碳化硅薄膜,通过改变反应前驱物及流量比调节薄膜的室温光致发光性质。实验发现在一定范围内随着流量比R(CH_4/SiH_4)的提高,氢化碳化硅薄膜的光致发光峰位蓝移且发光强度增强;同时反应前驱物中的氢会极大影响氢化碳化硅薄膜的发光强度。通过椭偏仪(Ellipsometer)测量了薄膜的光学常数,发现薄膜沉积速率随着流量比R的增加而降低;傅里叶红外光谱仪(FTIR)测试表明Si-C有序度随着流量比的增加而增大。同时研究了三维纳米线结构对多态碳化硅薄膜发光性质的影响。光致发光测试结果表明三维纳米线结构可以有效提高薄膜的光致发光强度。     

微波ECR-CVD法制备a-C:F:H膜的红外吸收及其光学带隙

改变CHF3 CH4 流量比R =[CHF3] ([CHF3]+[CH4 ]) ,采用微波电子回旋共振等离子体化学气相沉积 (MWECR CVD)方法沉积a C :F :H薄膜。a C :F :H薄膜的结构和光学带隙使用傅立叶变换红外光谱和紫外 可见光谱来表征。红外结果表明 ,在低流量比R(R <6 4 % )下 ,薄膜的红外特征结构主要以 CF(10 6 0cm- 1 ) , CF2(112 0cm- 1 )以及 CHx(2 80 0～ 30 0 0cm- 1 )的伸缩振动为主 ;在高流量比R(R >6 4 % )下 ,薄膜表现为类聚四氟乙烯(PTFE)的结构特征 ,典型的红外特征峰是位于 12 2 0cm- 1 处的 -CF2 反对称伸缩振动。薄膜的光学带隙Eg 随流量比R的变化表现为先降后升。进一步研究表明 ,薄膜中的H和F浓度调制着薄膜的CC共轭双键结构 ,使光学带隙Eg 从 2 37到 3 3之间变化     

PECVD法制备a-Si1-xCx:H薄膜的结构及光学性能研究

a-Si1-xCx:H的禁带宽度能随着薄膜中碳和氢的含量的变化而发生改变.深入了解薄膜中的键合情况及其对薄膜光学带隙的影响尤为重要.本文采用PECVD法,以硅烷(SiH4)和甲烷(CH4)为反应气源,通过选用不同的沉积功率及不同的组成制备出a-Si1-xCx:H薄膜,并采用红外光谱、喇曼光谱及紫外可见光谱等分析测试手段对薄膜中Si-C键的形成及其对光学能隙的影响进行了研究分析.分析表明Si-C键的形成几率及Si-C键的形成能力随着C和Si的含量接近而显著增加,Si-C键随着沉积功率的提高显著增加.研究得出,薄膜的光学能隙Eg受到a-Si1-xCx:H薄膜中的键合情况及薄膜缺陷态的影响.Eg随着薄膜中Si-C键含量的增加而变大,随着薄膜中的H含量的减少缺陷态的增加而减小.     

调控CN_x薄膜的紫外可见波段光学性能研究北大核心CSCD

采用等离子体增强化学气相沉积(PECVD)在不同衬底温度(常温、50、100、150、200℃)下制备了碳氮(CNx)薄膜,并对其形貌、结构及光学性能进行了研究。通过扫描电镜得出随着衬底温度的升高,薄膜由疏松逐渐变得致密。X射线光电子能谱分析表明:薄膜的结合健有sp^2C=C、sp^3C-C、sp^2C=N和sp^3C-N。随着衬底温度的升高,sp^2C=C的比例没有明显变化,sp3C-C比例逐渐增大(28.6%~36.4%),sp^3C-N的比例也逐渐增大(21.4%~33.4%),而sp^2C=N的比例减小(40.2%~21%)。反射光谱和吸收光谱显示:随着衬底温度的升高,薄膜在200~800 nm波段内的反射率增大(8%~40%),吸收率减小(92%~60%)。进一步推导得到薄膜的光学带隙随着衬底温度的升高而增大(2.5~3.57 e V),主要由薄膜中sp^2C=N减少导致的。本文实现了对CN_x薄膜在紫外可见波段范围内的光学带隙的调控。     

调控CN_x薄膜的紫外可见波段光学性能研究

采用等离子体增强化学气相沉积(PECVD)在不同衬底温度(常温、50、100、150、200℃)下制备了碳氮(CNx)薄膜,并对其形貌、结构及光学性能进行了研究。通过扫描电镜得出随着衬底温度的升高,薄膜由疏松逐渐变得致密。X射线光电子能谱分析表明:薄膜的结合健有sp~2C=C、sp~3C-C、sp~2C=N和sp~3C-N。随着衬底温度的升高,sp~2C=C的比例没有明显变化,sp3C-C比例逐渐增大(28.6%~36.4%),sp~3C-N的比例也逐渐增大(21.4%~33.4%),而sp~2C=N的比例减小(40.2%~21%)。反射光谱和吸收光谱显示:随着衬底温度的升高,薄膜在200~800 nm波段内的反射率增大(8%~40%),吸收率减小(92%~60%)。进一步推导得到薄膜的光学带隙随着衬底温度的升高而增大(2.5~3.57 e V),主要由薄膜中sp~2C=N减少导致的。本文实现了对CN_x薄膜在紫外可见波段范围内的光学带隙的调控。     

脉冲激光沉积法制备Ge-Se-Bi硫系玻璃薄膜的结构

采用脉冲激光沉积法制备了(GeSe2)100-x-Bix(x=0~12)硫系玻璃薄膜。测量了薄膜的光学透射谱、吸收谱和拉曼光谱。薄膜的光学短波吸收边对应于电子的间接带间跃迁,并由此计算出其光学带隙。拉曼光谱分析表明Bi含量的增加,减小了玻璃的平均键能,导致光学带隙由1.94 eV减小到1.11 eV。Tauc斜率由486 cm-1/2eV-1/2减小到178 cm-1/2eV-1/2。退火过程中的热漂白效应减小了玻璃的结构无序性,使得薄膜的光学带隙和Tauc斜率相应增大。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.