在线同位素分离器中空阴极靶离子源

本文描述兰州中国科学院近代物理研究所的在线同位素分离器中空气阴极靶离子源的设计原理、结构和特性。对Ar和Xe的调试结果。分离器的分辨本领达到700-1200。满足高分辨的要求。     

An efficient furan synthesis using heterogeneous catalysis

A wide variety of 3-alkyne-1,2-diols have been found to undergo exceptionally clean 5-endo-dig cyclisations followed by dehydration at ambient temperature to give the corresponding furans in essentially quantitative yields when exposed to 10 mol % of 10% w/w silver(I) nitrate absorbed on silica gel.     

Novel program versus disturb window characterization for split-gate flash cell

In this letter, a new methodology for program versus disturb window characterization on split gate flash cell is presented for the first time. The window can be graphically illustrated in V/sub wl/ (word-line)-V/sub ss/ (source) domain under a given program current. This method can help us understand quantitatively how the window shifts versus bias conditions and find the optimal program condition. The condition obtained by this method can have the largest tolerance for program bias variations. This methodology was successfully implemented in 0.18-/spl mu/m triple self-aligned (SA3) split-gate cell characterization to provide program condition for 32 M products.     

双结π环自发磁化的研究

研究了超导双结π环的自发磁化现象.讨论了双结π环可能发生自发磁化的条件，指出了自发磁化条件不仅与电感参数β有关，而且与两结临界电流之比有关.并通过分析自由能证明自发磁化是稳定的状态.最后给出了讨论结果和渐进行为. 关键词： 双结π环 自发磁化 自由能     

On the invariants of base changes of pencils of curves,I

The main purpose of this paper is to prove the nonnegativity of the basic invariants of base changes of a surface fibration, which is conjectured by Xiao Gang. For this purpose we obtain some new inequalities between the invariants of the singularities ofz ^d =f(x, y). This work is supported by the National Natural Science Foundation of China and by the Science Foundation of the University Doctoral Program of CNEC. This paper is corrected while the author is visiting Max-Planck-Institut für Mathematik in Bonn.     

Simultaneous measurement of whole in-plane displacement using phase-shifting ESPI

A novel method for simultaneously measuring whole field in-plane displacements by using optical fiber phase-shifting electronic speckle pattern interferometry (ESPI) is presented in this paper. A 1 × 4 single mode optical fiber beamsplitter is employed to split the laser beam into four beams of equal intensity. One pair of fibers is utilized to illuminate the diffuse target at equal angles in the horizontal plane so it is sensitive only to horizontal in-plane displacement. Another pair of optical fibers is set to be sensitive only to vertical in-plane displacement. The polarization directions of light emitted by fibers are the same for each pair, but are at a right angle between pairs. The optical fibers are equal in length for each pair, but are not equal between two pairs. In this case the speckles are interference between each pair of fibers, thus the horizontal and vertical displacement components can be obtained simultaneously. By means of a fiber phase shift technique we can obtain the quantitative data of whole field displacements. This method has made it possible to study the in-plane displacement of a thin metal plate, and the examples of the results are shown to demonstrate the novel method.     

Efficient method for estimating directions-of-arrival of partiallypolarized signals with electromagnetic vector sensors

We have developed a high-resolution ESPRIT-based method for estimating the directions-of-arrival of partially polarized signals with electromagnetic vector sensors, each of which provides measurements of the complete electric and magnetic fields induced by electromagnetic signals. The method is computationally efficient since unlike many high-resolution methods, it does not involve searching across a multidimensional array manifold. In addition, the method has two variants, of which one is applicable to scenarios where a priori information about the array system, such as the sensor positions, is unavailable     

Impact of Ge implantation on the electrical characteristics of TiSi2 p+/n shallow junctions with an a-Si (or apoly-Si) buffer layer

A new technology for forming a titanium-silicide shallow junction by combining germanium implantation with an amorphous-silicon (or a poly-silicon) buffer layer has been proposed for MOSFETs. The use of a buffer layer between Ti and Si can avoid the consumption of bulk-silicon and the recession of TiSi₂ film into the source/drain junctions during the silicidation process. In this study, the important role of germanium-implantation on the formation of TiSi₂ contacted p⁺/n junctions was examined. After subsequent implantation of Ge⁺ and B⁺ into the TiSi₂ film, samples were annealed at different temperatures to form p ⁺/n junctions and C54-TiSi₂. Since the penetration of titanium atoms was suppressed due to the germanium-implantation, the periphery leakage and the generation leakage were improved and TiSi₂/Si interfaces were even smooth. Therefore, p⁺/n junctions with a very low leakage current (0.192 nA/cm ² at -5 V) and an excellent forward ideality factor (n≈1.002) can be obtained. From the secondary ion mass spectrometry (SIMS) analysis, the junction depth is 400     

Si-implantation activation annealing of GaN up to 1400°C

Implant activation annealing of Si-implanted GaN is reported for temperatures from 1100 to 1400°C. Free electron concentrations up to 3.5×10²⁰ cm⁻³ are estimated at the peak of the implanted profile with Hall mobilities of ∼60 cm²/Vs for annealing at 1300°C for 30 s with an AIN encapsulant layer. This mobility is comparable to epitaxial GaN doped at a similarly high level. For annealing at ≥1300°C, the sample must be encapsulated with AIN to prevent decomposition of the GaN layer. Channeling Rutherford backscattering demonstrates the partial removal of the implant damage after a 1400°C anneal with a minimum channeling yield of 12.6% compared to 38.6% for the as-implanted spectrum. Scanning electron microscope images show evidence of decomposition of unencapsulated GaN after a 1300°C anneal and complete sublimation after 1400°C. The use of AIN encapsulation and annealing at temperatures of ∼1300°C will allow the formation of selective areas of highly doped GaN to reduce the contact and access resistance in GaN-based transistors and thyristors.     

3d过渡金属原子单层在Pd(001)表面磁性的第一性原理研究

用第一性原理基础上的超软赝势方法的总能计算，研究了3d过渡金属(Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn)在Pd(001)表面的单层p(1×1)和c(2×2)结构的表面磁性和总能. 所得结果表明：对于Sc, Ti, V和Cr只存在p(1×1)的铁磁性结构，而Mn只有c(2×2)的反铁磁结构存在. Fe, Co和Ni这三种元素上述两种结构都存在，但是总能上p(1×1)的铁磁结构要低些，因此是比较稳定的结构. 而Cu和Zn在该表面上的单层中不存在上述两种结构. 对于V的p(1×1)铁磁结构，计算得到的每个V原子磁矩为2.41μ_B，大于用全电子方法得到的0.51μ_B. 两种计算方法得到其他金属原子 (Cr，Mn，Fe，Co，Ni)的表面磁矩比较相近，都比孤立原子磁矩略小. 关键词： Pd(001)表面 过渡金属原子单层 表面磁性