金属有机化学气相沉积法制备钛酸铅铁电薄膜

利用低压ＭＯＣＶＤ工艺分别在（００１）取向的ＬａＡｌＯ_３，ＳｒＴｉＯ_３和重掺杂硅单晶衬底上制备ＰｂＴｉＯ_３铁电薄膜，并通过Ｘ射线衍射谱对薄膜的微结构进行分析．Ｘ射线θ－２θ扫描显示硅衬底上得到了ＰｂＴｉＯ_３多晶薄膜，另两种衬底上得到了择优取向的ＰｂＴｉＯ_３薄膜．ＬａＡｌＯ_３衬底上的ＰｂＴｉＯ_３薄膜有ａ和ｃ两个取向，也就是薄膜中存在着９０°畴结构，而生长在ＳｒＴｉＯ_３衬底上的ＰｂＴｉＯ_３薄膜中只存在ｃ方向的择优取向．由于薄膜的尺度效应，发现ｃ轴晶格常数与块材相比均缩短．Ｘ射线的φ扫描验证了后两类薄膜的外延特性，利用同步辐射的高强度和高能量分辨率用摇摆曲线方法研究了这两种外延薄膜的品质，进一步证明了ＳｒＴｉＯ_３衬底上的ＰｂＴｉＯ_３薄膜的单畴特性．利用重掺杂的硅衬底作底电极，测量显示直接生长于硅衬底上的ＰｂＴｉＯ_３多晶薄膜具有良好的铁电性能 关键词：     

等离子体噻吩聚合膜的研究及I+注入的掺杂效应

以噻吩为单体,在等离子体环境中聚合成致密的有机膜。利用Rutherford背散射(RB2S)和质子弹性反冲(ERD)、傅里叶红外谱(FTIR)测定了膜的成分和结构;从近红外-可见-紫外光的反射和透射谱,运用传递矩阵方法研究了膜的光学性质;此外,还探讨了24keV的I⁺离子束的注入对等离子体噻吩聚合膜的掺杂效应。结果表明,注入层内电荷载流子的输运机理可用Mott的可变自由程跳跃(VRH)理论给以解释。 关键词：     

Si_（1－x）Ge_x／Si定向耦合器的研制

在运用ＳｉＧｅ脊形波导单模条件和有效折射率法分析ＳｉＧｅ／Ｓｉ定向耦合器结构参数的基础上，采用分子束外延和各向异性腐蚀技术制备出Ｓｉ１－ｘＧｅｘ／Ｓｉ（ｘ＝０．０５）单模定向耦合器．在波长为１．３μｍ时，平均串音小于－１８．１ｄＢ，输出功率耦合效率达到９８．１％     

Design and performance analysis of beam steering birefringent mercurous chloride acousto-optic device

I.IntroductionThepcrformanccsofAcousto-optic(AO)dcviccareoftenlimitcdbythepropertiesofAOmcdiawhenitisusedinAOsigna1processingsystems.Thespectrumanalyzersandcorre1ationreceivers,forinstancc,areexpcctcdtoimprovcthereso1utionanddynamicrangcwhilereducingtheproccssorvolume.Rccent1y,ancwclassofmateria1s,themercurousha1ides,promiscstocontributeimportantsolutionstosuchnccdsandisrefincdtopractica1uti1izations.Themecurousha1ideweconsidcrinthispapcrismecurouschloride(Hg,C1,).Thesing1ecrystalofHg,Cl…     

Kinetic Studies of Electrochemical Oxidation of 1,3-Benzenedithiol

The electrochemical oxidation of 1, 3-benzenedithiol was investigated in a 0. 100 mol/L tetrabutylammonium perchlorate/acetonitrile electrolyte. The electrochemical techniques used were potential sweep, bulk electrolysis, rotating disc and the potential step method. The combination of the techniques yielded the number of electrons transferred per molecule, the reaction order, the transfer coefficient, the diffusion coefficient and concentration of dithiol anions, the standard heterogeneous rate constant as well as the formal potential and equilibrium constant of the preceeding dissociation reaction. This paper also illustrates the methods for studying the electrode kinetics of reactions which (a) involve a chemical reaction preceeding the electron-transfer process, (b) have insoluble polymer products, and (c) are totally irreversible.     

Determination of total ammonium-nitrogen and free ammonia in a fermentation medium by sequential injection analysis

Summary Automated methods for the determination of ammonium and ammonia are reviewed, and techniques based on gas diffusion using a semi-permeable membrane were selected for the determination of both total ammonium-nitrogen and free ammonia in fermentation samples. A simple and robust instrument based on sequential injection analysis (SIA) consisting of a piston pump and two selector valves was used. Two different methods of ammonia detection, the Berthelot method and detection using pH-indicators, have been evaluated and compared. The indicator method showed higher reproducibility and the range of determination could easily be adjusted to match the concentrations of the samples. The range of determination could be adjusted from 0.05 mmol/l to 350 mmol/l, depending on choice of acceptor solution. This method has been evaluated with fermentation medium samples and tested on-line in a yeast fermentation process.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

High throughput VLSI DSP using replicated finite rings

This paper discusses strategies for implementing DSP systems using residue replication. The theory, recently introduced by two of the authors, uses formal polynomial ring mappings, from binary representations, to direct product ring implementation of integer processing arrays. The mapping produces completely independent computational arrays each computing over the same ring. This paper describes an architecture and processing array to implement, and take advantage of, the special computational ring structures that result from the mapping. A brief review of the theory and mapping techniques, is followed by the discussion of the architecture and VLSI design of an efficient inner product processing array using Fermat Primes.     

Deep levels,electrical and optical characteristics in SnTe-Doped GaSb Schottky Diodes

The GaSb layers investigated were grown directly on GaAs substrates by molecular beam epitaxy (MBE) using SnTe source as the n-type dopant. By using admittance spectroscopy, a dominant deep level with the activation energy of 0.23-0.26 eV was observed and its concentration was affected by the Sb₄/Ga flux ratio in the MBE growth. A lowest deep-level concentration together with a highest mobility was obtained for GaSb grown at 550°C under a Sb₄/Ga beam equivalent pressure (BEP) ratio around 7, which should correspond to the lowest ratio to maintain a Sb-stabilized surface reconstruction. In the Hall measurement, an analysis of the temperature-dependent mobility shows that the ionized impurity concentration increases proportionally with the sample’s donor concentration, suggesting that the ionized impurity was introduced by an SnTe source. In addition, optical properties of an undoped p-, a lightly and heavily SnTe-doped GaSb layers were studied by comparing their photoluminescence spectra at 4.5K.     

Dynamic programming implementation on array processor architectures

Dynamic Programming (DP) applies to many signal and image processing applications including boundary following, the Viterbi algorithm, dynamic time warping, etc. This paper presents an array processor implementation of generic dynamic programming. Our architecture is a SIMD array attached to a host computer. The processing element of the architecture is based on an ASIC design opting for maximum speed-up. By adopting a torus interconnection network, a dual buffer structure, and a multilevel pipeline, the performance of the DP chip is expected to reach the order of several GOPS. The paper discusses both the dedicated hardware design and the data flow control of the DP chip and the total array.This work was supported in part by the NATO, Scientific and Environmental Affairs Division, Collaborative Research Grant SA.5-2-05(CRG.960201)424/96/JARC-501.