一种渐变掺杂型pin光探测器的高速响应性能研究

高速光探测器是高速光纤通信系统和网络中的关键器件,它要求光探测器具有宽的频率响应带宽和高量子效率。垂直入光型pin光探测器的高速性能和量子效率均受到吸收层厚度的限制。为了改善其高速性能,采用InGaAsP材料作为吸收层以及限制层渐变掺杂的方法,对垂直入光型pin光探测器的高速响应性能进行了理论研究和仿真,结果表明,高速响应达到了40GHz。与不采用渐变掺杂浓度的同种结构光探测器相比,高速响应性能显著提高。     

谐振腔增强型光探测器的高速响应性能研究

高速长波长光探测器是高速光纤通信系统和网络的关键器件，它要求光探测器具有宽的频率响应带宽和高量子效率。常用的PIN光探测器由于量子效率和高速性能均受到吸收层厚度的牵制，使得二者相互制约，成为一对矛盾。谐振腔增强型(RCE)光探测器为这一矛盾的解决提供了有效的方案。基于谐振腔增强型光探测器的实际设计和制作模型，分析了器件吸收层中的光场分布，并将其运用于载流子的连续方程，从理论上详细地分析了器件的高速响应特性，给出了计算结果。针对研制的高速长波长谐振腔增强型光探测器，进行了理论分析和实际器件测试的结果比较，得到了比较一致的结果。     

基于双吸收结构的谐振腔增强型光探测器

为了实现对传统谐振腔增强型（RCE）光探测器的优化,提出了一种具有双吸收结构的RCE光探测器。首先从理论上分析了它的量子效率和高速响应特性,然后将其与传统的RCE光探测器进行了比较。结果表明,双吸收结构RCE光探测器在保持高速响应特性的基础上,其量子效率较传统RCE光探测器得到了进一步提高。实验上成功制备了双吸收结构的...     

Ge/Si波导集成型APD器件的仿真分析

设计了一种Ge/Si波导集成型雪崩光电二极管(APD).器件采用将Si波导层置于Ge吸收层之下的结构,光经波导层进入吸收层只需一次耦合,降低了光的损耗,提高了光的吸收率和光电流.采用silvaco软件对器件的结构和性能进行仿真,结果表明:器件的雪崩击穿电压为-28 V,最大内量子效率达到89％,在1.15～1.60 μm范围内具有较高响应度,峰值波长位于1.31μm,单位响应度最高达0.74 A/W,3 dB带宽为10 GHz.     

一种具有平顶陡边响应的InP基长波长可调谐光探测器的设计

在一镜斜置三镜腔型光探测器的基础上提出了一种适用于波分复用系统的具有平顶陡边响应的可调谐光探测器结构.该器件由双半波滤波器结构的滤波腔和具有斜镜结构的吸收腔构成,实现了量子效率与光谱响应线宽间的解耦,具有高响应速度与高量子效率;同时,其光谱响应具有良好的平顶陡边特性和窄的光谱响应线宽,并且具有较大的调谐潜力.     

Si基Ge薄膜共振腔增强型光电探测器的设计与模拟

设计了Si衬底上Ge薄膜共振腔增强型光电探测器的器件结构,理论计算了上下反射镜Si/Si O2的对数、吸收区Ge薄膜的厚度、有源区面积等参数对器件的外量子效率、带宽等性能的影响。当器件上下反射镜Si/Si O2的对数分别为2和3,Ge薄膜的厚度为0.46μm,器件的台面面积小于176μm2时,探测器在中心波长1.55μm处的外量子效率达到0.64,比普通结构提高了30倍,同时器件的带宽达到40 GHz。     

基于湿法腐蚀工艺的高性能黑硅光电探测器

采用基于硝酸/氢氟酸/磷酸/硫酸混合液的湿法腐蚀工艺,实现了高吸收效率的黑硅结构的制备与工艺集成,获得了具有近红外响应增强效果的黑硅PIN光电探测器,并与未集成黑硅的PIN光电探测器的性能参数进行了对比测试.测试结果显示,黑硅光电探测器在1 060 nm波长下的响应度达到0.69 A/W(量子效率80.7％),较未集成黑硅的器件提高了 116％;黑硅探测器暗电流小于8 nA,响应时间小于8 ns,电容小于9 pF,与未集成黑硅的器件相当.得益于工艺兼容性,所采用的黑硅技术具有广泛应用于硅基近红外PIN,APD,SPAD,SPM等光电探测器的潜力,可显著提高器件的响应率、量子效率、响应速度、击穿电压温度系数等性能.     

单片集成GaAs基长波长谐振腔光探测器的研究

介绍了一种GaAs基的长波长谐振腔增强型(RCE)光探测器.通过两步生长法,在GaAs村底上异质外延生长了InP-InGaAs-InP的p-i-n光吸收结构和GaAs/AlAs的分布布拉格反射镜(DBR).所制备的器件在1 549.4 nm处获得了67.3%的量子效率和17 nm的光谱响应线宽,在1 497.7 nm处获得了53.5%的量子效率和9.6 nm的光谱响应线宽,而InGaAs吸收层厚度仅为200 nm.采用单片集成法,工艺简单、易于产业化,随着缓冲层技术的发展,此种RCE光探测器的性能还将获得进一步提升.     

特殊图案透明欧姆接触微结构提高谐振腔增强型光探测器的响应性能

为解决谐振腔增强型(RCE)光探测器的耦合效率和响应速率的矛盾,提出了采用特殊图案透明欧姆接触的微结构及其制备工艺方案,从而使得在器件入光面积不变的情况下,欧姆接触部分的总面积显著减小,在不影响器件量子效率的前提下达到减小电容、提高响应速率的目的。在台面面积为50μm×50μm的情况下,获得了18 GHz的响应带宽。研制的谐振腔增强型光探测器的响应速率得到了显著的提高。     

1064nm RCE探测器光电响应特性分析

对1064nm谐振腔增强型(RCE)光电探测器(PD)的光电响应特性进行了分析研究.利用MBE生长技术得到有源区分别为量子阱和量子点的1064nm RCE探测器的外延片,并对制作的探测器进行了各种光电特性测试.结果表明量子阱结构的RCE探测器量子效率峰值达到57%,谱线半宽6～7nm,峰值波长1059nm;而量子点结构的RCE探测器量子效率峰值达到30%,谱线半宽5nm,峰值波长1056nm.通过分析量子效率和吸收系数之间的关系,对两种结构器件的吸收进行了比较,发现虽然量子点探测器的吸收小,但通过合理设计共振腔等方法也可以达到较高的量子效率.两种结构的器件都有很好的I-V特性.     

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.