提高微通道板对低能电子探测效率的技术途径

为了提高静电聚焦型微通道板光电倍增管探测效率,重点研究微通道板的探测效率。分析影响微通道板对电子探测效率大小的主要因素,利用微通道板探测效率的理论模型,考虑在垂直入射到输入面的情况下,模拟计算出不同能量(E_e<1 keV)的入射电子打入非开口区对探测效率的贡献,结合开口区域的探测效率,即获得微通道板总的探测效率,并把模拟计算结果与实际测量相比较,两者基本一致;通过在微通道板的输入端面和通道内壁蒸镀高二次电子发射系数的材料、改变电极蒸镀方式和增加开口面积比,获得接近100%的探测效率,进而有效地提高了这种光电倍增管的探测效率。     

混合式光电探测器

混合式探测器(Hybrid Photodetector,HPD)作为一种新型的光电探测器件,是真空与半导体类结合型探测器件。HPD包括沉积在输入光窗表面的光电探测阴极、固态半导体阳极芯片和保持系统真空度的固态阳极。工作时,光信号通过沉积在输入光窗表面的光电阴极转化为光电子,经过高能电场加速后获得高能量轰击阳极半导体芯片表面,产生大量的电子空穴对,电子空穴对在半导体内部进行迁移,并通过自身的雪崩效应实现倍增,最终以电流信号输出。该探测器摒弃了传统的光电倍增管的微通道板(Micro Channel Plate,MCP)等倍增器件,克服了倍增单元信号易饱和的缺陷,增大了探测器的动态范围。HPD探测器综合了光电倍增管的高灵敏度和半导体芯片优异的空间和能量分辨率,具有探测面积大、探测灵敏度高、倍增效应强、动态范围宽等优点。在高能物理、医学成像和天体物理中有着重要的应用。此外,该探测器具有多种结构,分为近贴聚焦结构、交叉聚焦结构和漏斗聚焦结构,能够满足不同使用范围的探测需求;随着半导体阳极技术的发展,HPD阳极从单一芯片逐渐过渡到阵列式阳极结构,满足了大面积探测的需求。同时数字式读出和倍增信号技术的封装技术的发展,提高了HPD探测器的信号倍增和读出速度,改善了器件的集成化程度,有利于探测信号读出速率和信噪比的提升。近年来,其单光子计数和高动态响应等能力逐步被重视,将会在未来的光电探测领域发挥更为重要的作用。     

基于微通道板光电倍增管性能研究

近年来,微通道板光电倍增管(MCP-PMT)是指以微通道板为电子倍增系统的光电倍增管,与传统的静电聚焦打拿极相比,在结构上使得电子从光电阴极到阳极的距离大大减小,加上微通道板的电子倍增特性等优点,使该种光电倍增管在较多领域得到了广泛应用,研究其性能,对于设计、制造高性能的微通道板光电倍增管具有指导意义.基于这种情况,本文简要介绍了光电倍增管的国内外研究现状,并对两者进行了对比分析,对基于微通道板光电倍增管的结构及工作原理进行了叙述,然后对光电倍增管的响应性能、抗电磁场性能、增益性能和暗电流性能进行了研究,从而为关注这一话题的研究人员提供理论依据.     

高动态范围微通道板

微通道板是一种电子图象增强器件,它广泛用于各种信号和图象增强系统。其中许多,如象转换管、象加强器、空间光调制器、光电倍增器、阴极射线管,以及平视显示、头盔显示、夜视仪、电子快门、条纹相机、光子探测和质谱仪系统等,都要求微通道板     

一种大尺寸微通道板型光电倍增管

针对高能物理、核物理等国家大科学装置对核心探测器件的需求,研究不同于金属打拿极型倍增系统的大尺寸微通道板型光电倍增管。该光电倍增管最主要的特点是具有20 in（1 in=2.54 cm）的低本底玻壳和微通道板型倍增极结构,使用Sb-K-Cs阴极作为光电转换阴极,该阴极对350~450 nm波段光子的量子效率高,倍增极采用两片微通道板,在电压比较低的情况下可实现107的倍增能力,从而提高了光电倍增管的探测效率和单光子探测能力。与传统的金属打拿极型光电倍增管相比,20 in微通道板型光电倍增管是一种全新的产品结构,具有单光子峰谷比高、本底低、响应时间快、后脉冲比例小等特点。     

硅微通道板像增强器的研究

微通道板作为电子倍增器件可以对电子、离子、紫外和软X射线进行探测和成像.传统微通道板制备是采用玻璃纤维拉制和氢还原等技术,提出分别采用半导体体微加工和电化学腐蚀制备硅微通道板的新技术.在干法刻蚀中采用 ICP 技术制备了孔径为 6～20 μm、间隔4～8 μm、长径比 15～30 的硅微通道板,初步试验结果为对于长径比为 16 的样品,电子增益为 102 数量级.同时,开展了湿法电化学腐蚀技术制作硅微通道板的研究,分析讨论了电化学腐蚀微通道板的机理.结果表明,干法和湿法刻蚀技术可以制备高长径比硅微通道板,与 ICP 技术型比,电化学腐蚀具有较低的成本.     

像增强器的进展促进了光谱相机的发展

长期以来,致冷CCD相机在多路传输光谱探测领域有着广泛的应用.然而,用一台CCD相机进行时间选通实验,其速度显然很慢,即使采用快速机械快门,其时间选通也受限于几十ms.针对这一局限性,致冷相机的制造商们研制了一种增强型电荷耦合器件(ICCDs).增强型CCD探头田两个有源器件组成,即像增强管和CCD阵列.入射光子撞击像增强管的光电阴极导致电子发射,这些电子由几百V的选通电压加速到一块微通道板上,然后在该微道板上产生二次发射使电子倍增,在横穿微通道板时,被施加大约800V的电压.微通道板的窄通道在电子穿越时引导     

光电倍增管的噪声指数

前言极微弱光的检测技术在近代科学技术研究领域里受到广泛的重视,例如高分辨率的喇曼散射、生物发光、天文分光、原子吸收分光光度检测以及其它非线性光学测量等,分别要求检测输出功率微弱至每秒仅只有数个光子(10~(-19)瓦左右)的光信息,或者同属于微弱光检测范畴的另一种形式,它是以高强度的光入射状态下,检测出调制度为10~(-5)～10~(-6)的极微弱强度的调制信号。检测极微弱光的检测器,通常都使用光电倍增管,它比其它的器件,除了有光电变换机能之外,还具备有宽频带、高增益、低噪声的倍增系统,以及易于进行数据处理等特点,由于光电倍增管具有这种近于理想放大器的倍增系统,使它在现代电子线路里占有非常优越地位。     

电离效应对EBCMOS中电子倍增层增益的影响研究

采用蒙特卡罗模拟方法研究了电子轰击互补金属氧化物半导体(EBCMOS)成像器件中高能电子轰击半导体时产生的电离效应对电荷收集效率和电子倍增层增益的影响。分析了入射电子能量、p型衬底层掺杂浓度、电子倍增层和钝化层厚度对电荷收集效率和增益的影响。结果表明,增加入射电子能量(小于4 keV)、减小电子倍增层和钝化层厚度、降低掺杂浓度等是提高电荷收集效率和电子倍增层增益的有利途径,可为获得高增益的EBCMOS器件提供理论支撑。     

内耦合型EBCCD的技术研究

电子轰击电荷耦合器件(EBCCD)是一种微弱光信号成像器件,由于采用了内耦合的背照电荷耦合器件(CCD)结构,大大提高了该器件的探测灵敏度以及信噪比,使其探测的弱光下限能更低.采用国产面照CCD,成功研制出了具有背照功能的CCD以及能耐电子轰击的EBCCD.简单介绍了这种器件的工作原理、结构特点以及关键研究内容,并列出了实验分析及结果.     

半导体器件的发展与固态纳米电子器件研究现状

简要回顾了半导体电子器件由真空电子管到固体晶体管,直至纳米电子器件的发展历程。分别比较了不同的半导体电子器件的材料、理论和所采用的制备技术。在此基础上综述了当前较热门的纳米电子学和固态纳米电子器件,并由纳米器件的分类简单介绍了当前固态纳米电子器件的三个部分,即量子点、谐振隧穿器件和单电子晶体管。最后对半导体器件的发展提出了展望。     

A novel control circuit for proximity focused microchannel plate image-intensifiers

 A proximity focused microchannel plate image-intensifier(MCP I~2)can always serve as a fast optical shutter due to its high temporal and spatial resolution,large spectral and input intensity range,high gain as well as the possibility of transient recording of single-shot events. The MCP I~2 tube combined with a gating pulse generator constitutes the simplest image-converter camera with a high light gain and a fast response.In this paper,three different modes of gating for a typical 18mm“Generation Ⅱ”MCP I~2 tube(ITT type F4111)are compared.On the basis of the above considerations,a new circuit is developed for fast gating at the photocathode of an image- intensifier and for the generation of large-amplitude nanosecond pulses.With this gating generator, a camera exposure time of about 2 ns has been obtained.The matching of the gating generator with the image-intensifier is also discussed.A simple and efficient method is presented to eliminate the multi-exposure effect which must be avoided in high-speed photography.     

Microchannel plate inverter image intensifiers

The characteristics of microchannel plate/inverter image intensifiers (MCP/III) are described. This type of image tube is shown to be well suited to some night vision applications. The 25 mm MCP/III developed by the authors has a minimum magnification of 0.96, a maximum distortion of 5 percent, and a limiting resolution of 10 cycles/mm. Its luminance gain is about 10⁵at input levels up to 2 × 10^-3fc when an S20 photocathode and a P20 phosphor screen are employed. The operational life of a MCP/III is generally a few thousand hours. Accurate life data can be determined, for a given application, after the operating input light level value, the applied MCP potential, and the duty cycle are established. The unique bulb design allows the tube high voltage power supply to be placed around the tube envelope within a 50 mm diameter and reduces the total interelectrode capacitance of the gating/focus electrode to 7 pF.     

硅微通道板电子倍增器

本文采用感应耦合等离子体刻蚀机(ICP)和低压化学气相淀积(LPCVD)技术制备了硅微孔列阵和连续打拿极,得到具有一定性能的硅微通道板.同时分析讨论了微孔列阵的表面形貌、反应离子刻蚀的尺寸效应以及电子增益系数等问题.与传统工艺相比,新工艺将微通道板基体材料与打拿极材料的选择分开、微孔列阵形成和连续打拿极制作过程分开,以MCP性能的突破找到了新途径.     

Atomistic and electrical simulations of a GaN-AlN-(4H)SiC heterostructure optically-triggered vertical power semiconductor device

In this paper, a comprehensive simulation study is conducted to investigate the switching characteristics, gain, and breakdown voltage of a GaN-AlN-(4H)SiC based optically-triggered (OT) heterostructure vertical power semiconductor device (PSD). It comprises a 1 nm AlN buffer layer between the GaN and SiC heterointerface to achieve a reasonable compromise between lattice mismatch and lower forward drop. The results are compared with an all-(4H)SiC OT PSD. The all-(4H)SiC homostructure PSD is based completely on SiC and has no buffer layer. Further, it has the same structure, dimensions, and doping densities as that of the GaN-AlN-(4H)SiC based heterostructure PSD. While there have been studies on GaN-AlN-SiC lateral heterostructures, their primary focus has been on lateral conduction in the GaN structure with a thick (typically >300 nm) AlN buffer layer residing on top of a SiC substrate. Such an approach will not be useful for our vertical PSD because of the thick AlN layer. As such, first, a scaled molecular dynamics simulation (MDS) is carried out in DMol³ emulating the GaN-AlN-(4H)SiC heterointerface pn junction of the vertical PSD (with 1 nm AlN buffer) to assess the possibility of vertical conduction and stability of the heterointerface by calculating the density of states (DOS) at the Fermi level and the potential energy, respectively. Subsequently, detailed electrical simulations of the GaN-AlN-(4H)SiC and all-(4H)SiC vertical PSDs are carried out in Silvaco to assess their switching performances, gain, on-state drop, and blocking capabilities. The overall results indicate that, the GaN-AlN-(4H)SiC vertical PSD provides superior switching performance and optical absorption compared to the all-(4H)SiC vertical PSD, while the latter provides better gain. The blocking capabilities and forward drops are found to be comparable for both the PSDs from a practical standpoint.     

微通道板斜切角对像增强器性能的影响研究

采用试验对比分析的方法,从MCP斜切角对像增强器的MCP噪声因子、分辨力、MCP增益三方面的影响展开研究。试验结果表明,MCP斜切角在5°～12°范围内时,MCP噪声因子与MCP斜切角呈抛物线关系,当MCP斜切角为9°时,MCP噪声因子最小;分辨力与斜切角呈负相关关系,当MCP斜切角为5°时,分辨力最大;MCP增益随斜切角的增加呈抛物线变化,当MCP斜切角为9°时,MCP增益最大。这主要是因为改变MCP斜切角后,光电子进入MCP通道前端二次电子发射层的角度深度不同,激发出的二次电子数及电子在MCP输出端形成的散射斑半径存在差异。若要选择最佳MCP斜切角,必须综合考虑不同场景下对像增强器主要性能指标的要求。     

窄脉冲刚管调制器

雷达发射机和高功率微波装置对大功率刚管调制器的需求越来越大,尤其是窄脉冲调制器非常重要。随着大功率半导体开关器件技术的进步,窄脉冲刚管调制器逐渐变为现实。为了降低成本、满足系统小型化的要求,仅使用一个耐压900V的开关管,通过高变比脉冲变压器的耦合,就得到了脉冲宽度400ns、脉冲电压达到12kV的调制脉冲。     

Neutron irradiation of insulated gate field effect transistors

Insulated gate field effect transistors and polysilicon-gated capacitors were irradiated with fast (10 keV <E < 2 MeV) neutrons. As expected, damage to the bulk silicon was detected as a degradation in the minority carrier lifetime. Optically assisted electron injection was employed for the first time to examine neutral electron trap and fixed positive charge generation in the gate insulator of the devices. While fixed positive charge densities of ≤6 x 10¹⁰ cm⁻² were detected, little or no neutral electron trap generation was observed. The small density of coulombic defects observed in the insulator could be accounted for fully by the known flux of gamma rays associated with the neutron irradiation process. This indicates that fast neutrons passing through a thin gate oxide do not produce significant amounts of damage in the oxide. Somewhat surprisingly, it was found that 1.5 keV X-rays created similar lifetime degradation effects in the bulk silicon, as did fast neutrons, even though this photon energy is not believed to be capable of producing bulk damage in the form of atom displacement in either the semiconductor or the insulator. The minority carrier lifetime of the silicon could be restored to initial values following either neutron or x-ray exposure by annealing in H₂ for 30 min at 400° C.     

微道板技术进展（一）

本文系统地评述了微道板技术的最新进展，包括玻璃表面结构的研究、增益衰减模型、微道板新的制造方法和各种高性能新器件的特性，重点是新器件的设计思想。     

热轧薄板测量系统中激光波长的优选

研究了绿光、红光和红外光激光光源和热轧薄板干扰光对热轧薄板厚度测量的影响.利用电炉加热Cu薄片模拟生产现场热轧薄板环境,采用双光路激光三角法,在基于位置敏感器件(PSD)的调制光源和非调制光源的两种测量系统上,分别选用不同激光光源对热轧薄板厚度进行测量.实验结果表明,在两种测量系统中,测量精度均受到了热轧薄板干扰光的很...