长波碲镉汞材料As掺杂激活研究

利用离子注入工艺实现长波碲镉汞材料的As掺杂,As作为掺杂介质表现出两性掺杂行为,而As只有占据Te位成为受主才能形成P型碲镉汞材料。通过对砷掺杂碲镉汞材料在汞气氛中进行退火,分析注入退火引起的样品电学性质的变化,对砷激活退火采用的汞压、温度及时间进行了研究,利用霍尔测试和二次离子质谱仪(SIMS)等手段分析激活效果,研究发现,高温富汞热退火可以实现碲镉汞As激活。     

低暗电流高温工作碲镉汞红外探测器制备技术

报道了与传统的n-on-p结构相比具有更低暗电流的p+-on-n型碲镉汞红外探测器的研究进展。通过水平滑舟富碲液相外延生长的方法在碲锌镉衬底上原位生长In掺杂碲镉汞n型吸收层材料,然后再分别采用As离子注入技术和富汞垂直液相外延技生长技术实现了P型As外掺杂的p+-on-n型平面型和双层异质结台面型两种结构的芯片制备。碲镉汞探测器的主要缺点是需要低温制冷,期望碲镉汞探测器在不降低性能的前提下具有更高的工作温度(High Operating Temperature,HOT),成为红外探测器技术发展的主要方向。本文对基于标准的n-on-p(Hg空位)掺杂工艺及新研制的p-on-n型As离子注入及异质结制备技术的探测器进行了高温性能测试,测试结果表明采用p-on-n型的碲镉汞探测器能够实现更高的工作温度。     

碲镉汞p-on-n长波异质结探测器材料的制备研究

报道了碲镉汞p+-on-n长波双层异质结材料和异质结台面器件的研究结果,重点研究了p+-on-n型双层异质结材料制备技术。通过水平滑舟富碲液相外延生长的方法在碲锌镉衬底上原位生长In掺杂碲镉汞n型吸收层材料,然后再采用富汞垂直液相外延技术制备p型As原位掺杂的碲镉汞cap层材料,从而获得p+-on-n型双层异质结材料,并通过湿法腐蚀、台面刻蚀以及钝化等工艺得到碲镉汞 p+-on-n长波异质结台面型器件。p+-on-n异质结器件结构可以有效克服少子寿命偏低等问题,在长波及甚长波波段具有更低的暗电流和更高的R0A值,这对于解决目前长波碲镉汞红外探测器暗电流大、结阻抗低的问题,提高长波及甚长波波段碲镉汞红外焦平面器件的性能具有重要的意义。     

分子束外延碲镉汞薄膜的砷掺杂技术

Ⅴ族元素As在碲镉汞中具有较小的扩散系数,在非本征p型掺杂中得到广泛应用,在p-on-n型高性能探测器及双色或多色探测器应用方面优势明显。对分子束外延掺As碲镉汞薄膜的几种生长技术的基本原理进行了简单介绍,并对各方法存在的优缺点进行了对比分析;同时对As杂质在碲镉汞材料中的掺杂形态、杂质激活退火工艺及杂质激活率等进行了总结分析。对MBE As掺杂在第三代多层膜结构器件的应用方面提出了建议。     

分子束外延锗基碲镉汞薄膜原位砷掺杂研究

报道了基于Ge衬底分子束外延碲镉汞原位As掺杂材料的研究结果,进行了As掺杂碲镉汞薄膜生长的温度控制研究;分析了As束流对材料晶体质量的影响,结合SIMS测试技术得到了As杂质掺杂浓度与束源炉加热温度的关系;并利用傅里叶红外光谱仪、X射线双晶衍射、EPD检测等手段对晶体质量进行了分析表征,结果显示利用MBE方法可以生长出晶体质量良好、缺陷密度低的碲镉汞薄膜;进一步研究了As杂质的激活退火工艺及不同退火条件对材料电学参数的影响。     

MBE生长碲镉汞的砷掺入与激活

采用As掺杂和激活技术制备的p+-on-n异质结材料是获得高性能长波碲镉汞红外焦平面器件的关键技术之一,得到了广泛关注.采用变温IV拟合的方法,对不同As掺入浓度与器件结性能相关性进行了分析,发现降低结区内As掺杂浓度可以有效抑制器件的陷阱辅助隧穿电流.拟合结果表明,较高浓度的Nt很可能与高浓度As掺入相关.因此As的稳定均匀掺入和激活被认为是主要技术挑战.实验研究了分子束外延过程中Hg/Te束流比与As掺入效率的关系,发现相对富Hg的外延条件有助于提高As掺杂效率.研究还发现As的晶圆内掺杂均匀性与Hg/Te束流比的均匀性密切相关.对As的激活退火进行了研究,发现在饱和Hg蒸汽压中采用300℃/16h+420℃/1 h+240℃/48 h的退火条件能明显提升碲镉汞中As原子的激活率.     

As掺杂碲镉汞富碲液相外延材料特性的研究

对富碲液相外延As掺杂碲镉汞(HgCdTe)材料的研究发现,其电学性能存在着不稳定性,材料霍尔参数的实验数据与均匀材料的理论计算结果也不能很好的吻合.通过采用剥层变温霍尔测量和二次离子质谱(SIMS)测试对材料纵向均匀性进行检测的结果显示,外延材料中的As在高温富汞激活退火过程中具有向材料表面扩散的效应,导致在表面形成了高于主体层浓度1～2个量级的高浓度表面层,并导致了AsTe受主的浓度在HgCdTe薄膜中呈非均匀分布.考虑这一效应并采用双层模型的霍尔参数计算方法后,As掺杂HgCdTe液相外延材料的电学行为得到了较好的解释,并较为准确地获得了退火后材料表面层与主体层的受主浓度及受主能级等电学参数.     

碲镉汞材料中Hg空位、Au、As掺杂的研究进展

碲镉汞材料是制造红外探测器的基础,高性能红外探测器对碲镉汞材料的要求越来越高。为了提升器件性能,必须提高碲镉汞材料的电学性能。而掺杂是一个很好的选择。碲镉汞材料掺杂可以分为n型和p型两种。对于n型掺杂来说,In是一种理想的掺杂剂,其掺杂研究目前已比较成熟。相对而言,p型掺杂研究还不是那么深入。Hg空位、Au、As掺杂均为碲镉汞材料中常见的p型掺杂手段。通过分析和总结近些年的部分相关文献,介绍了碲镉汞材料中Hg空位、Au、As掺杂的研究进展。     

As掺杂p型碲镉汞材料的研究进展

非本征p 型掺杂碲镉汞材料可以有效克服少子寿命偏低等问题,提高长波和甚长波红外焦平面器件的性能。本文重点阐述了As 掺杂实现p型掺杂的基础性原理,以及在器件方面最新研究进展,为今后As掺杂碲镉汞材料的研究提供依据。     

碲镉汞As掺杂技术研究

对于MBE原位掺杂，HgCdTe的N型掺杂比较容易，而P型掺杂相对来说难度比较大。作为掺杂杂质的As表现出两性掺杂行为，在富Te的条件下生长，As有很大的几率进入到阳离子位置处。而As必须进入Te位才能参与导电，表现为P型。因此，采取了多种方法，现已获得10^16-10^18坤cm^-3掺杂水平的P型材料。在成功实现As的掺杂后，研究人员对激活退火做了一些研究。研究发现，需要在汞压下经过高温退火，As原子才能占据Te位成为受主杂质。对As在碲镉汞中的扩散系数也进行了研究。     

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.     

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.