弛豫型铁电体

本文简要地介绍弛豫型铁电体PMN的模型,然后根据作者对钽钪酸铅(PST)中的有序—无序转变和锆钛酸镧铅(PLZT)中极化—去极化过程的研究对弛豫型铁电体极化机制的发展情况以及有关微畴及超顺电态问题作了简要的讨论。 作者成功地观察到了PST和PLZT中的微畴,并且取得了非常清晰的照片。由于实验证实微畴的存在,有关弛豫型铁电体的极化理论将可能出现新的解释。     

弛豫铁电单晶热释电探测器读出电路的设计

以(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-xPT或PMNT)(PMN-xPT,或PMN-PT)为代表的弛豫铁电单晶具有非常高的热释电系数、比较低的热扩散系数、比较稳定的化学性能,是一种综合性能优异的热释电材料.利用弛豫铁电单晶可以制备出高性能的红外光传感器,针对用这种新型热释电材料制成的红外...     

复合钙钛矿介质陶瓷结构对称性的旋进电子衍射研究

采用最新的旋进电子衍射技术研究了Ca(Mg1/3Ta2/3)O3复合钙钛矿陶瓷的晶体结构.在一定的旋进角下,旋进电子衍射可以很好地消除传统电子衍射中的动力学效应,揭示了Ca(Mg1/3Ta2/3)O3结构中B位离子有序是决定其晶体结构的关键因素,而通过旋进电子衍射花样中对称元素的直观确认,并结合会聚束晶体点群确认方法,证实了Ca(Mg1/3Ta2/3)O3陶瓷属于单斜2/m点群.     

准同型相界附近PMN-PT陶瓷的介电性能

采用铌铁矿预产物合成法制备了组成在相界附近的(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-PT)弛豫铁电陶瓷。陶瓷样品X-射线衍射相组成和相结构分析表明:所有陶瓷样品均为纯钙钛矿相,无任何其他杂相出现;且组成在x=0.33处存在一准同型相界(MPB),在该相界附近三方相和四方相共存,而远离该相界则分别为纯三方相和四方相。相界附近组成随PT摩尔分数增加,介电峰变得尖锐,频率弥散减弱,即介电弛豫程度减弱。这主要是由于四方相增多,三方相减少,从而使弛豫铁电体变为正常铁电体。     

钛铌镁酸铅【Pb（Mg1／3Nb2／3）I3-xPbTiO3】弛豫铁电体的研究进展

弛豫铁电体钛铌镁酸铅Pb(Mg1／3Nb2／3)O3-xPbTiO3(PMNT),简称PMNT,不仅具有良好的介电性能和电机械性能,还具有良好的电致伸缩和压电性能,是制备高K电容器、传感器和激发元等的良好材料。其在微电子领域的应用前景非常广阔,本文就Pb(Mg1／3Nb2／3)O3-xPbTiO3,简称(PMNT)弛豫铁电体的最新研究进展进行综述性的报道。     

Ca0.28Ba0.72Nb2O6单晶中无公度调制结构、电畴结构与相变的TEM研究

介电温谱测量结果表明,钨青铜型Ca0.28Ba0.72Nb2O6(CBN28)单晶在252 ℃附近经历了从正常铁电体到弛豫铁电体的相变.用透射电子显微镜研究了该单晶中的无公度调制结构、畴结构及其演变.由室温[110]带轴电子衍射花样确定无公度调制波矢q=(1/2)c* (1 δ)(a*-b*)/4,其中无公度参数δ=0.09.高分辨像给出了无公度调制结构的直接证据.这种无公度超晶格结构是两种正交超晶胞结构均匀混合的结果.CBN28单晶中存在高密度沿c轴走向直径约50 nm～500 nm的长钉状180 °电畴.在电镜中原位升温至220 ℃左右,开始出现许多直径仅几纳米的细条状畴;温度继续上升时这种细条状畴渐增多.这种宏畴到微畴转变对应于在铁电相变点Tc附近的正常到弛豫铁电转变.刚好在Tc以下,还观察到经零场冷却的纳米针状畴.     

PbZrO-3陶瓷中180°畴壁形态及其原位再生的TEM研究

畴结构及其在外场下的动力学行为对铁电材料的电学性质起着决定性作用.与BaTiO-3和Pb(Zr,Ti)O-3等钙钛矿型铁电体相比,人们对PbZrO-3等反铁电体中的畴结构及其动力学行为的了解少得多[1-3].Tanaka等人曾用TEM观察到了PbZrO-3单晶中的反铁电180°畴壁,并用α-fringe理论确定了180°畴壁两侧的位移矢量[3].但至今还没有关于反铁电体中180°畴壁形态及其形成规律的系统研究报道.我们知道,在铁电体中形成180°畴是为了降低退极化能.但反铁电体中的自发极化本身就是反向的,不存在退极化场,可见反铁电体与铁电体中的180°畴有本质不同.此外,PbZrO-3中自发极化两两反平行,如果极化反转生成180°畴,那么180°畴壁的构型可能不同于铁电180°畴壁的.     

BMN掺杂NBT压电陶瓷的介电特性研究

采用传统陶瓷制备方法,制备了一种新无铅压电陶瓷材料(1-x)Na1/2Bi1/2TiO3-xBi(Mg2/3Nb1/3)O3.研究了Bi(Mg2/3Nb1/3)O3掺杂对(Na1/2Bi1/2)TiO3陶瓷晶体结构、弥散相变与介电弛豫行为的影响.X-射线衍射(XRD)分析表明,在所研究的组成范围内陶瓷材料均能形成纯钙钛矿固溶体.材料的介电常数-温度曲线显示陶瓷具有2个介电反常峰Tt和Tm,低掺杂的样品低频介电常数在居里温度以上异常增加.该体系陶瓷表现出与典型弛豫铁电体明显不同的弛豫行为.根据宏畴-微畴转变理论探讨了该体系陶瓷产生介电弛豫的机理.     

无压烧结制备0.88PMN-0.12PT高度透明铁电陶瓷的显微结构研究

用传统的无压烧结工艺制备出稀土元素La掺杂的高度透明纯钙钛矿相0.88Pb(Mg1/3Nb2/3)O3-0.12Pb Ti O3(简称0.88PMN-0.12PT)铁电陶瓷。当陶瓷样品厚度为0.8 mm时,在1550 nm处透光率达67%,接近其理论极限。电滞回线测量结果表明该组分透明陶瓷为典型的弛豫铁电体。显微结构观察结果表明陶瓷非常致密,晶粒排列规则,晶界结合强度高,多呈穿晶断裂,晶界干净,且厚度2 nm。     

BSZN固溶体系统的有序结构与相转变

XRD分析表明,(Ba1-xSrx)(Zn1/3Nb2/3)O3系统中生成了一定的有序结构,即1∶2和1∶1超晶格。随着Sr含量的增加,晶体结构由无序的立方相向有序的赝立方相转变,呈现对称性下降的趋势,且高角度处衍射峰展宽。(Ba1-xSrx)(Zn1/3Nb2/3)O3钙钛矿结构中氧八面体畸变的发生是相转变形成、有序相产生及晶体结构对称性下降的根本原因。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.