碲镉汞红外探测器高低温循环特性研究

由于卫星长寿命的要求与机械制冷机有限寿命的矛盾,制冷机必须采用间歇式工作模式,因此星载碲镉汞红外探测器在太空中工作会经受从常温(20℃)到低温(-173℃以下)的成千上万次的温度循环,这给红外探测器带来了新的可靠性问题.本文介绍了自主研发的高低温循环试验系统,液氮致冷,温度循环范围为295K到100K.利用试验系统对两种型号的红外探测器组件进行了温度循环试验可靠性研究,测试和统计了循环试验前后的电阻、信号和噪声变化,针对具体试验结果做了分析和解释,为器件的工艺研发和改进提供了参考.     

碲镉汞红外探测器高低温循环特性研究

由于卫星长寿命的要求与机械制冷机有限寿命的矛盾，制冷机必须采用间歇式工作模式，因此星载碲镉汞红外探测器在太空中工作会经受从常温（20℃）到低温（-173℃以下）的成千上万次的温度循环，这给红外探测器带来了新的可靠性问题。本文介绍了自主研发的高低温循环试验系统，液氮致冷，温度循环范围为295K到100K。利用试验系统对两种型号的红外探测器组件进行了温度循环试验可靠性研究，测试和统计了循环试验前后的电阻、信号和噪声变化，针对具体试验结果做了分析和解释，为器件的工艺研发和改进提供了参考。     

InSb焦平面探测器高低温循环特性研究

制冷型InSb红外焦平面探测器工作时需降温至低温(80 K),器件在整个生命周期会经受从常温(300 K)到低温(80 K)的上千次高低温循环。针对该型探测器开展了高低温循环特性试验,测试和分析了上千次高低温循环过程中器件光电性能、杜瓦热负载和J-T制冷器特性的变化。试验结果表明,探测器可以经受至少2 000次高低温循环,并且探测率变化的幅度5.5%、响应率变化的幅度4.8%、盲元数未发生增加。研究结果为器件的工艺研发和改进提供了参考。     

锑化铟红外焦平面探测器盲元失效问题的研究

锑化铟红外焦平面探测器将要在寿命周期中于室温到77K的温度范围内工作几千次.由于不同材料的热膨胀系数不一致,热循环会造成焊点疲劳和失效,最终导致焦平面探测器失效.通过研制的温度循环设备,了解了铟焊点失效的原因,并用ANSYS软件对铟柱的机械失效现象进行了分析.通过分析铟柱高度和可靠性之间的关系,得出铟柱高度的增加可以提高探测器的可靠性.介绍了焊接可靠性的评价方法.改进后的焊接工艺可大幅提高探测器的可靠性.     

用于低温半导体器件筛选的新型温度循环设备

在某些情况下斯特林制冷机采用间歇式工作方式,以延长卫星在太空中的服务年限,因此由斯特林机致冷的低温半导体器件如HgCdTe中长波红外探测器会经受成千上万次从-173℃以下到常温的温度循环,这个过程可能会造成器件的失效.为了研究器件的失效机理和可靠性,帮助筛选器件,本文介绍了一种自制新型的温度循环实验设备,型号TCE-a.经过数千次温度循环,设备满足器件筛选实验要求.     

杜瓦/快速起动节流制冷器集成体及杜瓦/斯特林循环制冷机集成体

红外探测器必须在大约80K低温下才能正常工作。因此,它一定要装在杜瓦中,而且要有节流制冷器或制冷机给其提供低温环境。随着红外技术的迅速发展,出现了杜瓦/快速起动节流制冷器集成体和杜瓦/斯特林循环制冷机集成体。杜瓦/快速起动节流制冷器集成体将杜瓦与快速起动节流制冷器制做为一体,消除了原与节流制冷器相配合的杜瓦芯柱,降低了能耗,诚小了体积,减轻了质量。这种集成体中的快速起动节流制冷器是以玻璃为材料的平面状快速起动节流制冷器,它采用两级制冷,第一级选用氮-碳氢化合物混合气体为工质,第二级选用纯氮气体为工质,在快速起动节流制冷器內装有微型喷射泵,这样,不仅提高了节流制冷器制冷效率,而且可使快速起动节流制冷器制冷温度达70K以下,有利地提高了红外探测器的工作性能。杜瓦/斯特林循环制冷机集成体将杜瓦与斯特林循环制冷机制做为一体,斯特林循环制冷机冷指与杜瓦芯柱合二为一,红外探测器直接安装于斯特林循环制冷机冷指之上,消除了芯柱热传导、斯特林循环制冷机与杜瓦之间连接的热偶合器及其产生的热阻,较大地降低了系统能耗,减少了斯特林循环制冷机体积,减轻了斯特林循环制冷机质量。     

不同斯特林制冷机驱动盖板的探测器热仿真

斯特林制冷机作为红外探测器的重要组成部分,可为红外探测器提供必需的低温工作环境,确保红外探测器正常工作,有效的斯特林制冷机散热设计,可提高红外探测器的工作性能。本文基于Ansys 有限元软件,对不同制冷机驱动盖板结构的红外探测器组件进行了热仿真计算,结果表明,红外探测器组件内制冷机驱动板和电机外壳的温度较高,其最高温度出现在驱动板的驱动元器件位置。制冷机驱动盖板由平板式结构改为凸台式结构、增大驱动盖板和导热垫的导热系数可有效改善红外探测器组件的散热性能,红外探测器组件的最高温度可减小8.5。     

红外焦平面探测器贮存寿命试验研究

本文以红外焦平面探测器为研究对象,在充分分析历年来国内红外焦平面探测器贮存寿命试验数据的基础上,研究了产品的失效模式和失效机理,并对贮存寿命试验前后关键参数指标变化量进行了深入分析,为全面评价红外焦平面探测器产品质量和可靠性提供了依据,为后续红外焦平面探测器的标准制修订工作奠定了基础。     

HgCdTe探测器In焊凸点的失效及有限元分析

卫星工作时,由斯特林机致冷的HgCdTe中长波红外探测器会经受从-173℃以下到常温的成千上万次温度循环.由于不同材料的热膨胀系数(TEC)不匹配,这样就会造成电极封装的疲劳和失效,进而影响卫星的正常工作.利用中科院上海技术物理研究所研制的温度循环设备TCE-a,模拟了真空环境下的斯特林制冷机的开关机模式,发现了In焊凸点的两种失效模式.运用有限元方法,对In焊凸点的失效进行了力学分析.     

液氮温区集成式数字温度传感器设计

温度传感器是制冷型红外焦平面探测器的重要组成部分,它用于测量探测器工作温度,其输出用于制冷机控制,从而控制探测器温度。探测器的工作温度将直接影响探测器的性能,如信噪比、探测率和盲元率等。针对传统PN结温度传感器需要模拟信号处理电路及易受电磁干扰的弊端,设计了一种基于CMOS工艺的集成式数字温度传感器,可以集成到红外焦平面探测器读出电路中,直接通过SPI接口输出数字测温值。设计的集成式数字温度传感器采用0.35 m CMOS工艺流片,芯片面积为380 m500 m（不包含PAD）,在电源电压2.5 V和采样频率6.1次/s条件下,功耗为300 W,分辨率0.061 6 K。在77 K温度下输出的RMS噪声为0.148 K。测试结果表明,集成式数字温度传感器可以应用于制冷型红外焦平面探测器温度测量。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.