Metalorganic chemical vapor deposition of silver thin films for future interconnects by direct liquid injection system

Deposition of Ag films by direct liquid injection-metal organic chemical vapor deposition (DLI-MOCVD) was chosen because this preparation method allows precise control of precursor flow and prevents early decomposition of the precursor as compared to the bubbler-delivery. Silver(I)-2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionato-triethylphosphine [Ag(fod)(PEt₃)] as the precursor for Ag CVD was studied, which is liquid at 30 °C. Ag films were grown on different substrates of SiO₂/Si and TiN/Si. Argon and nitrogen/hydrogen carrier gas was used in a cold wall reactor at a pressure of 50–500 Pa with deposition temperature ranging between 220 °C and 350 °C. Ag films deposited on a TiN/Si diffusion barrier layer have favorable properties over films deposited on SiO₂/Si substrate. At lower temperature (220 °C), film growth is essentially reaction-limited on SiO₂ substrate. Significant dependence of the surface morphology on the deposition conditions exists in our experiments. According to XPS analysis pure Ag films are deposited by DLI-MOCVD at 250 °C by using argon as carrier gas.     

基于预前控制异步电机直接转矩控制方案的研究

在传统异步电动机直接转矩控制方案中，由于负载的变化规律不可预测，因此其常会带来较大的开关频率的变化，为此提出了一种基于预前控制的异步电动机直接转矩控制的方法。该方法依据前一个周期的磁链和转矩误差，对下一个开关周期所应施加到异步电动机的定子电压矢量进行预测，然后借助空间矢量PWM的方法，合成此开关电压矢量。样机实验结果表明，该方案不但能维持逆变器的开关频率基本恒定，而且还具有比传统直接转矩控制更为优良的动静态特性。     

ABB变频器在双馈发电机试验台上的应用

本文介绍了风力发电系统目前存在的技术方案，重点介绍了ABB用于双馈式风力发电系统的变频产品ACS800—67的特性，并对由其构建的发电机测试平台的案例进行了实验分析。     

Analysis of (π K<Superscript>+</Superscript>) and (K<Superscript>-</Superscript>, K<Superscript>+</Superscript>) hypernuclear production spectra in distorted-wave impulse approximation

We study the hyperon-nucleus potential with distorted-wave impulse wave approximation (DWIA) using the Green's function method. In order to include the nucleon and hyperon potential effects in Fermi averaging, we introduce the local optimal momentum approximation of target nucleons. We can describe the quasi-free Λ , Σ and Ξ production spectra in a better way than in the standard Fermi-averaged t -matrix treatments.     

ON DIRECT METHOD OF SOLUTION FOR A CLASS OF SINGULAR INTEGRAL EQUATIONS

In this article, by introducing characteristic singular integral operator and associate singular integral equations (SIEs), the authors discuss the direct method of solution for a class of singular integral equations with certain analytic inputs. They obtain both the conditions of solvability and the solutions in closed form. It is noteworthy that the method is different from the classical one that is due to Lu.     

P-channel Ge/Si Hetero-nanocrystal Based MOSFET Memory

The charge storage characteristics of P-channel Ge/Si hetero-nanocrystal based MOSFET memory has been investigated and a logical array has been constructed using this memory cell. In the case of the thickness of tunneling oxide T_ox=2nm and the dimensions of Si- and Ge-nanocrystal D_Si=D_Ge=5nm, the retention time of this device can reach ten years(~1×10~8s) while the programming and erasing time achieve the orders of microsecond and millisecond at the control gate voltage |V_g|=3V with respect to N-wells, respectively. Therefore, this novel device, as an excellent nonvolatile memory operating at room temperature, is desired to obtain application in future VLSI.     

Synthesis of perfluorinated functionalized, branched ethers

We wish to report synthesis of perfluorinated functionalized, branched ethers from their hydrocarbon analogues by direct fluorination. Yields up to 90%, with high purities, have been obtained at ambient temperature and pressure. This technique will likely develop into a new general method for producing perfluorinated, hyperbranched and dendritic polymers.     

A tentative approach to the direct simulation of drag reduction by polymers

An efficient technique for drag reduction uses dilute solutions of a few p.p.m. of polymers. A possible reduction in drag of up to 80% is achieved. Several experimental observations have been made which tend to indicate that the polymers modify the turbulence structures within the buffer layer. Flow visualisations have shown that the changes consist of a weakening of the strength of the streamwise vortices. Existing literature reveals no attempts of numerical simulation of this phenomenon. In this paper an approach is pursued by using a constitutive equation which relates the elongation viscosity to the local properties of the flow. According to this model this viscosity is large in zones where the amount of strain rate is greater than the amount of vorticity, and is zero when the vorticity exceeds the strain rate. Simulations have been performed in a “minimal channel” to give good resolution with a limited number of grid points. The accuracy of the method is tested by comparison with the results of other techniques. For simulations with polymers, quantitative comparisons cannot be made, but the results reproduce the qualitative outputs of the experiments. The mean streamwise velocity is modified in the buffer layer; the peak of the streamwise turbulent intensity, in wall units, increases and its maximum moves far from the wall; and the vertical turbulent intensity is largely reduced in the wall region. An interesting outcome from both the simulation and the experiments is that the strength of the longitudinal vortices is reduced when the polymers are present.     

一步法合成苯乙烯催化剂表面积炭对活性的影响

应用ＥＳＲ，空气气氛下ＤＴＡ，氢气氛下ＴＰＳＲ，ＩＲ等技术手段，对反应后催化剂的积炭行为进行了研究。结果表明，反应后的催化剂表面不同程度地存在着不同类型和积炭，积炭是催化剂失活的主要原因。     

Synthesis and characterization of new thermally stable copoly(ester–amide)s from diester–dicarboxylic acids

Three new aromatic diester–dicarboxylic acids containing furan rings, namely, benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-phenyl ester-4,4^′-dicarboxylic acid, benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-phenyl ester-3,3^′-dicarboxylic acid and benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-naphthyl ester-2,2^′-dicarboxylic acid were synthesized by the reaction of benzofuro[2,3-b]benzofuran-2,9-dicarbonyl chloride with 4-hydroxybenzoic acid, 3-hydroxybenzoic acid and 3-hydroxy-naphthalene-2-carboxylic acid, respectively. Diester–dicarboxylic acids were characterized by FT-IR and NMR spectroscopy and elemental analyses. Then, these monomers were converted to aromatic copoly(ester–amide)s by their reaction with various aromatic diamines via the direct polycondensation. These polymers were characterized by viscosity measurements, solubility tests, FT-IR, Ultraviolet and ¹H-NMR spectroscopy and thermogravimetry. The polymers with inherent viscosities in the range of 0.16–0.37 dl/g in dimethyl sulfoxide at 30 °C were obtained in high yield. Most of them dissolved readily at room temperature in polar solvents. The synthesized copoly(ester–amide)s possessed glass-transition temperatures from 210–255 °C. The copoly(ester–amide)s exhibited excellent thermal stabilities and had 10% weight loss at temperature above 295 °C under nitrogen atmosphere.