Resolving Deep Sub-Wavelength Scattering of Nanoscale Sidewalls Using Parametric Microscopy

The quantitative optical measurement of deep sub-wavelength features with sub-nanometer sensitivity addresses the measurement challenge in the semiconductor fabrication process. Optical scatterings from the sidewalls of patterned devices reveal abundant structural and material information. We demonstrated a parametric indirect microscopic imaging (PIMI) technique that enables recovery of the profile of wavelength-scale objects with deep sub-wavelength resolution, based on measuring and filtering the variations of far-field scattering intensities when the illumination was modulated. The finite-difference time-domain (FDTD) numerical simulation was performed, and the experimental results were compared with atomic force microscopic (AFM) images to verify the resolution improvement achieved with PIMI. This work may provide a new approach to exploring the detailed structure and material properties of sidewalls and edges in semiconductor-patterned devices with enhanced contrast and resolution, compared with using the conventional optical microscopy, while retaining its advantage of a wide field of view and relatively low cost.     

Niobium and iron co-doped titania nanobelts for improving charge collection in dye-sensitized TiO2 solar cells

Niobium (Nb) and iron (Fe) co-doped titanium oxide nanobelts were prepared in a one-pot alkaline hydrothermal process followed by calcination treatment, and evaluated in TiO₂ nanoparticle-based composite anodes for dye-sensitized solar cells. Addition of Nb and Fe species caused an increase in donor density and trap-mediated charge transition, as characterized by electrochemical and photoluminescence analyses. Under illumination with simulated solar light, the co-doped single-crystalline nanobelts promoted photocurrent yield and open-circuit voltage, because they facilitate electronic conduction and chemical capacitance in the composite anodes. This improved photovoltaic performance is associated with the enhanced charge collection efficiency, mechanistically attributed to rapid electron transport and prolonged electron lifetime via shallow trapping sites. Results demonstrate that the Nb and Fe co-doped titania nanobelts are effective to provide longer electron diffusion lengths and favor charge accumulation during cell operation.     

The Rashba Effect on the Bound Polaron in a Parabolic Quantum Dot

The bound polaron ground state energy is calculated by the variational method of Pekar considering the influence of the Rashba SO interaction on the condition of electric?CLO phonon strong coupling in a parabolic quantum dot (QD). The relations on the bound polaron ground state energy with the parallel confinement length, the electron?CLO phonon coupling constant, the perpendicular confinement length and the Coulomb binding parameter are derived for a parabolic quantum dot.     

一种基于位置的WSAN密钥预分配方案

论文从无线传感器和执行器网络的信息传输方式出发,提出一种新的密钥预分配方案。方案充分利用执行器节点具有能量充足、存储器资源丰富、较强计算和通信能力等特点,结合部署位置信息,在执行器节点-执行器节点和执行器-传感器节点两个通信层上采用不同的密钥预分配方案。通过分析可知,新方案在连通性、安全性、计算和通信消耗上都有良好性能。     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

露天矿剥离洪峰控制技术研究现状

通过对目前国内外露天矿山剥离洪峰控制技术研究现状的分析,采用合理有效的方法均衡生产剥采比,控制并推迟剥离洪峰期的到来,使矿山的剥岩量得到均衡,优化剥离方案,减少矿山剥岩投资,以指导露天矿持续、高效、安全生产。     

硼掺杂对金刚石薄膜生长特性的影响

采用HFCVD方法制备了掺硼金刚石薄膜,通过扫描电子显微镜和X射线衍射光谱对样品的表面形貌及结构进行了分析.结果表明,随着硼含量的增加,薄膜中晶粒的取向由(100)变为(111),然后趋向于无序化.硼的掺入同样影响到孪晶晶粒的形态及生长因子α,使得α变小.通过对样品的Raman光谱分析,得出在适当的硼掺杂浓度下,孪晶的出现使金刚石薄膜中的应力得到松弛,从而中心声子线Raman位移红移较小.     

壳-芯型复合陶瓷材料的制备及其电磁特性

为了提高吸波剂对电磁波的吸收性能, 采用溶胶-凝胶法制备了表面包覆有一定厚度的炭黑薄膜的钛酸钡复合粒子. 并利用XRD和TEM方法对其形貌结构进行了分析; 同时研究了复合粒子的导电性能、电磁参数以及对电磁波的吸收性能. 结果表明: 钛酸钡颗粒的直径在50～70nm之间, 包覆层厚度为10～20nm. 包覆工艺显著改善了材料的导电性能并提高了介电常数, 而且随着复合粒子在吸波材料基体中的含量不同, 对电磁波的吸收性能也有着不同的影响: 当吸收材料中复合粒子含量达到或超过20wt%时, 复合粒子明显改善了吸收材料对电磁波的吸收性能.     

金红石TiO2基质中[MoO4]2-基团的上转换发光

在978nm激光二极管的激发下,Mo掺杂的TiO₂材料表现出很强的宽带上转换发光,该发光来源于[MoO₄]^2-基团的激发态³T₁,³T₂能级到基态¹A₁能级的电子跃迁,X射线衍射表明样品为金红石单一相,红外吸收光谱证实了[MoO₄]^2-的存在,由光电子能谱推测体系中还含有低价态的Mo离子,它们提供了上转换得以进行的中间态,高温下的氧化还原处理会改变低价Mo的数量,从而严重影响样品的发光行为。     

S-RHT FIXED-BED HYDROTREATING TECHNOLOGY FOR RESIDUE WITH HIGH SULFUR CONTENT

To meet the demands of processing residue with high sulfur content, Fushun Research Institute of Petroleum and Petrochemicals (FRIPP) successfully developed the fixed-bed residue hydrotreating technology (S-RHT), which is suitable for treating high sulfur residue to produce diesel oil with low sulfur content, the hydrotreated 350℃ residue is also a good feedstock for RFCC. Based on this technology, Maoming Petrochemical Company constructed the hydrotreating unit with a capacity of 2 Mt/a to treat high sulfur residue, in which loaded FZC series catalysts were developed by FRIPP. The unit was first put into commercial operation at the end of 1999. The commereial operation showed that the catalysts have good activities and the products meet the designed specifications.