Surface-enhanced fluorescence from copper nanoparticles on silicon nanowires

A method to enhance surface plasmon coupled fluorescence from copper nanoparticles on silicon nanowires is presented. Owing to resonant plasmons oscillation on the surface of Cu/Si nanostructure, the fluorescence peaks of several lanthanide ions (praseodymium ions, Pr3+,neodymium ions Nd3+, holmium ions Ho3+, and erbium ions Er3+) were markedly enhanced with the enhancement of maximal 2 orders of magnitude, which was larger than that caused by unsupported Cu nanoparticles. These results might be explained by the local field overlap originated from the closed and fixed copper nanoparticles on silicon nanowires.     

Controlled Synthesis of Various Hollow Cu Nano/MicroStructures via a Novel Reduction Route

Hollow Cu nano/microstructures are prepared by reduction of CuSO₄ · 5 H₂O with glucose by using a mild hydrothermal process. The X‐ray powder diffraction and energy‐dispersive X‐ray analysis indicate that the products are pure Cu and of cubic phase. The morphology of the products can be controlled between nanotubes and microspheres assembled from hollow nanoparticles by adjusting the concentration of sodium dodecyl sulfate. A series of experiments confirm that the concentration of the glucose and NaOH also play important roles in the formation of the hollow Cu nano/microstructures.     

Fabrication of Hollow Inorganic Microspheres by Chemically Induced Self‐Transformation

Two contrasting approaches, involving either polymer‐mediated or fluoride‐mediated self‐transformation of amorphous solid particles, are described as general routes to the fabrication of hollow inorganic microspheres. Firstly, calcium carbonate and strontium tungstate hollow microspheres are fabricated in high yield using sodium poly(4‐styrenesulfonate) as a stabilizing agent for the formation and subsequent transformation of amorphous primary particles. Transformation occurs with retention of the bulk morphology by localized Ostwald ripening, in which preferential dissolution of the particle interior is coupled to the deposition of a porous external shell of loosely packed nanocrystals. Secondly, the fabrication process is extended to relatively stable amorphous microspheres, such as TiO₂ and SnO₂, by increasing the surface reactivity of the solid precursor particles. For this, fluoride ions, in the form of NH₄F and SnF₂, are used to produce well‐defined hollow spheroids of nanocrystalline TiO₂ and SnO₂, respectively. Our results suggest that the chemical self‐transformation of precursor objects under morphologically invariant conditions could be of general applicability in the preparation of a wide range of nanoparticle‐based hollow architectures for technological and biomedical applications.     

Dependency of dishing on polish time and slurry chemistry in Cu CMP

In this paper the influences of slurry chemistry and thickness of the copper layer on dishing will be discussed. The dishing is studied for different patterns and variable polishing times. We found that the concentration of the oxidiser and the thickness of copper layer have a strong impact on dishing. The larger Cu features develop dishing at a higher rate than smaller structures during overpolishing. The experimental results lead to the following hypothesis for the Cu removal and surface passivation. The oxidizer (H₂O₂) reacts with Cu in an acidic slurry (pH 4) and Cu²⁺ ions are formed. The anions of the carboxylic acid react with Cu²⁺ ions and form an insoluble salt (R(COO)₂Cu) which passivates the surface. This passivation layer is removed in protruding areas by mechanical abrasion. Once removed from the surface, the ‘metallic soap’ particles are swept away by the turbulent motion in the slurry.     

Inside Front Cover: One‐Pot Synthesis and Hierarchical Assembly of Hollow Cu2O Microspheres with Nanocrystals‐Composed Porous Multishell and Their Gas‐Sensing Properties (Adv. Funct. Mater. 15/2007)

On p. 2766, Qinshan Zhu and co‐workers report on multishell hollow Cu₂O microspheres that are synthesized by a facile and one‐pot solvothermal route. A two‐step organization process, in which hollow microspheres of Cu₂(OH)₃NO₃ are formed first followed by reduction to Cu₂O by glutamic acid, leads to the special multishell and hollow microstructures. Interestingly, a Cu₂O gas sensor fabricated with the multishell microspheres shows a much higher sensitivity to ethanol than solid Cu₂O microspheres. Hierarchical assembly of hollow microstructures is of great scientific and practical value and remains a great challenge. This paper presents a facile and one‐pot synthesis of Cu₂O microspheres with multilayered and porous shells, which were organized by nanocrystals. The time‐dependent experiments revealed a two‐step organization process, in which hollow microspheres of Cu₂(OH)₃NO₃ were formed first due to the Ostwald ripening and then reduced by glutamic acid, the resultant Cu₂O nanocrystals were deposited on the hollow intermediate microspheres and organized into finally multishell structures. The special microstructures actually recorded the evolution process of materials morphologies and microstructures in space and time scales, implying an intermediate‐templating route, which is important for understanding and fabricating complex architectures. The Cu₂O microspheres obtained were used to fabricate a gas sensor, which showed much higher sensitivity than solid Cu₂O microspheres.     

Treatment of Copper from Cu CMP Waste Streams Using Polyethyleneimine

Commercially available Cu CMP waste treatment processes involve: 1) pretreatment chemistry using oxidizers to break down complexed copper resulting in precipitation of copper in the form of copper hydroxide; 2) microfiltration of both slurry particles and copper hydroxide; and 3) ion exchange to remove ${rm Cu}^{2+}$ ions. Ion exchange resins used to remove ${rm Cu}^{2+}$ ions are limited to only removing cations and also have a low efficiency in binding ${rm Cu}^{2+}$ ions. The treatment strategy to be evaluated here only requires using two processes to remove the copper from Cu CMP waste—filtration to remove the particles followed by chelation. This paper focuses on the chelation step. The chelator of interest is polyethyleneimine (PEI) bound to agarose beads. PEI removes both ${rm Cu}^{2+}$ ions and Cu-complexes. The particles from slurry in the actual Cu CMP waste were removed by filtration before the experiment. The results show that PEI has a higher binding capacity for ${rm Cu}^{2+}$ ions than ion exchange resins. Its performance and reproducibility did not change after multiple regenerations. Furthermore, PEI has the ability to bind Cu-complexes through electrostatic attraction. Although the bonds aren't strong, the result is more overall copper removal from the waste stream. The copper component of the Cu CMP waste was concentrated 12 fold using this system.      

Preparation of Fine Copper Powder With Chemical Reduction Method and Its Application in MLCC

In this paper, the preparation of fine copper powder with chemical reduction method was investigated. Polyhedron nonagglomerated monodispersed copper powders by the reaction of CuSO₄ldr5H₂O and ascorbic acid were synthesized at pH 6~7 and reaction temperature of 60degC~70degC. It was also found by X-ray diffraction (XRD) analysis that a mixture of copper and cuprous oxide could be obtained when [Cu(NH₃)₄]²⁺ was reduced by ascorbic acid. Reaction temperature and pH have great effects on efficiency and particle size of copper powders. Copper powders were applied as terminal electrode materials of base metal electrode-multilayer ceramic capacitor (BME-MLCC), and the microstructures, including cross section and interface, of copper thick film were discussed with scanning electron microscopy. The results indicated that copper thick film has a loose, porous cross section and a rough interface. The adhesion strength of copper electrode is high due to rough microstructure caused by interfacial reaction.     

One‐Pot Synthesis and Hierarchical Assembly of Hollow Cu2O Microspheres with Nanocrystals‐Composed Porous Multishell and Their Gas‐Sensing Properties

Hierarchical assembly of hollow microstructures is of great scientific and practical value and remains a great challenge. This paper presents a facile and one‐pot synthesis of Cu₂O microspheres with multilayered and porous shells, which were organized by nanocrystals. The time‐dependent experiments revealed a two‐step organization process, in which hollow microspheres of Cu₂(OH)₃NO₃ were formed first due to the Ostwald ripening and then reduced by glutamic acid, the resultant Cu₂O nanocrystals were deposited on the hollow intermediate microspheres and organized into finally multishell structures. The special microstructures actually recorded the evolution process of materials morphologies and microstructures in space and time scales, implying an intermediate‐templating route, which is important for understanding and fabricating complex architectures. The Cu₂O microspheres obtained were used to fabricate a gas sensor, which showed much higher sensitivity than solid Cu₂O microspheres.     

Self‐Established Rapid Magnesiation/De‐Magnesiation Pathways in Binary Selenium–Copper Mixtures with Significantly Enhanced Mg‐Ion Storage Reversibility

Rechargeable magnesium/sulfur (Mg/S) and magnesium/selenium (Mg/Se) batteries are characterized by high energy density, inherent safety, and economical effectiveness, and therefore, are of great scientific and technological interest. However, elusive challenges, including the limited charge storage capacity, low Coulombic efficiency, and short cycle life, have been encountered due to the sluggish electrochemical kinetics and severe shuttles of ploysulfides (polyselenide). Taking selenium as model paradigm, a new and reliable Mg‐Se chemistry is proposed through designing binary selenium‐copper (Se‐Cu) cathodes. An intriguing effect of Cu powders on the electrochemical reaction pathways of the active Se microparticles is revealed in a way of forming Cu₃Se₂ intermediates, which induces an unconventional yet reversible two‐stage magnesiation mechanism: Mg‐ions first insert into Cu₃Se₂ phases; in a second step Cu‐ions in the Mg_2xCu₃Se₂ lattice exchange with Mg‐ions. As expected, binary Se‐Cu electrodes show significantly improved reversibility and elongated cycle life. More bracingly, Se/C nanostructures fabricated by facile blade coating Se nanorodes onto copper foils exhibit high output power and capacity (696.0 mAh g^?1 at 67.9 mA g^?1), which outperforms all previously reported Mg/Se batteries. This work envisions a facile and reliable strategy to achieve better reversibility and long‐term durability of selenium (sulfur) electrodes.     

Simple Synthesis of Hollow Tin Dioxide Microspheres and Their Application to Lithium‐Ion Battery Anodes

Hollow tin dioxide (SnO₂) microspheres were synthesized by the simple heat treatment of a mixture composed of tin(IV ) tetrachloride pentahydrate (SnCl₄·5H₂O) and resorcinol–formaldehyde gel (RF gel). Because hollow structures were formed during the heat treatment, the pre‐formation of template and the adsorption of target precursor on template are unnecessary in the current method, leading to simplified synthetic procedures and facilitating mass production. Field‐emission scanning electron microscopy (FE‐SEM) images showed 1.7–2.5 μm sized hollow spherical particles. Transmission electron microscopy (TEM) images showed that the produced spherical particles are composed of a hollow inner cavity and thin outer shell. When the hollow SnO₂ microspheres were used as a lithium‐battery anode, they exhibited extraordinarily high discharge capacities and coulombic efficiency. The reported synthetic procedure is straightforward and inexpensive, and consequently can be readily adopted to produce large quantities of hollow SnO₂ microspheres. This straightforward approach can be extended for the synthesis of other hollow microspheres including those obtained from ZrO₂ and ZrO₂/CeO₂ solid solutions.     

激光对羟基磷酸铜的还原机理研究

为了研究激光选区金属化技术中，激光与尖晶石型化合物的相互作用机理，选用质优价廉、具有尖晶石结构的可见光和近红外光敏催化物质羟基磷酸铜(Cu₂(OH)PO₄)作为研究对象，利用X射线光电子能谱技术，探讨了波长为1064nm纳秒脉冲光纤激光、连续光纤激光和波长为355nm的纳秒脉冲紫外激光与羟基磷酸铜的相互作用机理。结果表明，3种激光都能将羟基磷酸铜中的+2价铜元素(Cu2+)还原为+1价铜元素(Cu+)，但还原过程随激光功率(0.13W~3.89W)或激光能量密度(2.76J/cm2~25.48J/cm2)的变化呈现不同的规律; 结合羟基磷酸铜的热性能分析和紫外可见光吸收光谱分析，初步判断，在上述还原过程中，可能同时存在光热反应和光化学反应。该研究为羟基磷酸铜作为一种新型的激光活性物质提供了理论基础。     

Self‐Assembly of Polyaniline—From Nanotubes to Hollow Microspheres

By simply changing the molar ratio of the dopant to monomer, the morphology of salicylic acid (SA)‐doped polyaniline (PANI) can be changed from one‐dimensional nanotubes (～ 109–150 nm in diameter) to three‐dimensional hollow microspheres (～ 1.5–3.1 μm in diameter) via a self‐assembly process. Freeze–fracture electron microscopy (FFEM) proved that hollow spherical micelles composed of SA/aniline act as templates in the formation of either nanotubes or hollow spheres. FTIR and X‐ray diffraction measurements suggest that the hydrogen bond of the –OH group of SA with the amine group of PANI might be a driving force for self‐assembling hollow microspheres, while the hydrogen bond through hydrogen and oxygen of the adjacent SA doped on the polymer chains results in short‐range order of the counter‐ions along the polymer chain in the nanotubes.     

柠檬酸在钴基铜互连CMP及后清洗的研究进展

钴(Co)具有较低的电阻率、良好的热稳定性、与铜(Cu)粘附性好等优点,可以替代钽(Ta)成为14 nm以下技术节点集成电路(IC) Cu互连结构的新型阻挡层材料。化学机械抛光(CMP)是唯一可以实现Cu互连局部和全局平坦化的方法,也是决定Co基Cu互连IC可靠性的关键技术。柠檬酸含有羟基,在电离后对金属离子有较强的络合作用,成为Co基Cu互连CMP及后清洗中的主要络合剂。文章评述了柠檬酸在Cu互连CMP及后清洗中的应用和研究进展,包括柠檬酸对Cu/Co去除速率选择比、Co的表面形貌以及Co CMP后清洗中Co表面残留去除等方面的影响,并展望了络合剂及Cu互连阻挡层CMP的发展趋势。     

不同氮氩比制备的W-Si-N薄膜的阻挡特性研究

研究了薄膜沉积条件之一——氮气和氩气流量比对超薄(10nm)W-Si-N薄膜作为铜扩散阻挡层的阻挡特性的影响。用薄层电阻、俄歇电子能谱(AES)、X射线衍射谱(XRD)、电容-电压(C-V)等方法系统研究了氮氩比对W-Si-N、Cu/W-Si-N/Si以及Cu/W-Si-N/SiO2/Si结构的热稳定性、电学稳定性的影响。实验发现,W-Si-N薄膜中氮含量对材料的阻挡特性起重要作用,高的氮氩比使薄膜中氮含量增高,薄膜对Cu的扩散阻挡特性增强。     

Colloidal synthesis and characterization of Cu2ZnSnS4 nanoplates

Synthesis of copper zinc tin sulphide (Cu₂ZnSnS₄) with nanoplate morphology was achieved through colloidal method using oleic acid as capping agent and solvent with 1-octadecene (1-ODE) at 240℃. X-ray diffraction (XRD) analysis shows that the synthesized nanoplates possessed pure kesterite phase. SEM analysis clearly shows the formation of nanoplates having the size of about 50-100 nm. Electron spin resonance (ESR) spectrum analysis of the prepared nanoplates shows that the valence state of copper (Ⅱ) which indicates the strong coupling with other metal ions. Thermo gravimetric/differential thermal analysis (TG/DTA) analysis shows the weight loss of sample at 450℃ predicting the loss of capping ligands on the surface of the nanoparticles. The possible mechanism for the conversion of nanoplate-like structures during synthesis was discussed. The results are discussed in detail.     

Investigation of surface morphology of copper-modified amorphous carbon films

A study of the surface morphology of copper-modified amorphous hydrogenated carbon films a-C:H(Cu) by scanning tunnel microscopy (STM) is reported. An algorithm is presented for the digital analysis of STM images to obtain the size distribution function for the longitudinal component of the surface relief. a-C:H(Cu) films were deposited by magnetron co-sputtering of graphite and copper onto two types of substrates: (100) n-Si with a heavily doped surface layer, and Si covered with a chromium layer. A mesoscopic surface structure of crystalline silicon, a chromium layer, and a-C:H(Cu) film has been revealed. A correlation between the structural elements of the film and the substrate is considered and a conclusion is made that inherent grains with characteristic size of 6–8 nm are formed in the film.     

花状纳米结构ZnS:Cu的制备与光学性质研究

采用水热法合成了具有花状纳米结构的ZnS:Cu粉末.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和荧光光谱仪研究了在不同正硅酸四乙酯(TEOS)含量的条件下制备的样品的物相、形貌与光致发光(PL)性质.测试结果表明:制备的ZnS:Cu样品都具有立方相闪锌矿结构;由于TEOS分子...     

Metal Nanocrystal‐Embedded Hollow Mesoporous TiO2 and ZrO2 Microspheres Prepared with Polystyrene Nanospheres as Carriers and Templates

Noble metal nanocrystals with different shapes and compositions are embedded in hollow mesoporous metal oxide microspheres through an ultrasonic aerosol spray. Polystyrene (PS) nanospheres are employed simultaneously as a hard template to create hollow interiors inside the oxide microspheres and as the carrier to bring pregrown metal nanocrystals, including Pd nanocubes, Au nanorods, and Au core/Pd shell nanorods, into the oxide microspheres. Calcination removes the PS template and causes the metal nanocrystals to adsorb on the inner surface of the hollow oxide microspheres. The catalytic performances of the Pd nanocube‐embedded TiO₂ and ZrO₂ microspheres are investigated using the reduction of 4‐nitrophenol as a model reaction. The presence of the mesopores in the oxide microspheres allows the reactant molecules to diffuse into the hollow interiors and subsequently interact with the Pd nanocubes. The embedding of the metal nanocrystals in the hollow oxide microspheres prevents the aggregation of the metal nanocrystals and reduces the loss of the catalyst during recycling. The Pd nanocube‐embedded ZrO₂ microspheres are found to exhibit a much higher catalytic activity, a much larger catalytic reaction rate, and a superior recyclability in comparison with a commercial Pd/C catalyst. This preparation approach could potentially be utilized to incorporate various types of mono‐ and multimetallic nanocrystals with different sizes, shapes, and compositions into hollow mesoporous oxide microspheres. Such a capability can facilitate the studies of the catalytic properties of various combinations of metal nanocrystals and metal oxide supports and therefore guide the design and creation of high‐performance catalysts.     

Template‐Free Preparation of Hollow Sb2S3 Microspheres as Supports for Ag Nanoparticles and Photocatalytic Properties of the Constructed Metal–Semiconductor Nanostructures

A simple and convenient Ostwald ripening route to the morphology‐ and phase‐controlled preparation of hollow Sb₂S₃ microspheres is developed. The hollow spheres are clusters of smaller microspheres if orange amorphous Sb₂S₃ colloid is used as the precursor, whereas, if starting from the yellow precursor, the products are regular hollow spheres. By selecting appropriate experimental conditions for ripening, the phase of the hollow Sb₂S₃ microspheres can be controlled. Amorphous and orthorhombic hollow spheres are prepared by ripening the colloidal precursors at ambient temperature and in an autoclave, respectively. The closed shell of hollow Sb₂S₃ spheres can be easily eroded by hydrochloric acid to form an open structure. By the in situ reduction of adsorbed Ag⁺ on the surface and interior of the hollow spheres, Ag nanoparticles are introduced into them, to form functional metal–semiconductor composites, the weight content of which is controlled by regulating the concentration of the Ag⁺ source and the adsorption time. The composite structures composed of Ag nanoparticles and hollow Sb₂S₃ spheres exhibit a remarkably enhanced absorption covering the UV and visible regions of the electromagnetic spectrum. A study of the photocatalytic properties of the composite structures demonstrates that exposure to both UV and visible light enables them to induce the rapid decomposition of 2‐chlorophenol. The degradation rate increases with a larger weight content of Ag in the composite structure.     

Template‐Assisted Formation of Rattle‐type V2O5 Hollow Microspheres with Enhanced Lithium Storage Properties

In this work, rattle‐type ball‐in‐ball V₂O₅ hollow microspheres are controllably synthesized with the assistance of carbon colloidal spheres as hard templates. Carbon spheres@vanadium‐precursor (CS@V) core–shell composite microspheres are first prepared through a one‐step solvothermal method. The composition of solvent for the solvothermal synthesis has great influence on the morphology and structure of the vanadium‐precursor shells. V₂O₅ hollow microspheres with various shell architectures can be obtained after removing the carbon microspheres by calcination in air. Moreover, the interior hollow shell can be tailored by varying the temperature ramping rate and calcination temperature. The rattle‐type V₂O₅ hollow microspheres are evaluated as a cathode material for lithium‐ion batteries, which manifest high specific discharge capacity, good cycling stability and rate capability.