钝化层及P型基底结构优化对电子轰击型有源传感器电荷收集效率影响的研究

为获得高增益的电子轰击型有源传感器(EBAPS)，对EBAPS成像器件中电子倍增层的电荷收集效率的影响因素进行了研究。基于载流子输运理论，采用蒙特卡罗方法研究了钝化层种类、厚度、入射电子能量、P型基底厚度和掺杂浓度对二次电子分布及收集的影响。结果表明：为提高入射电子的入射深度进而提高电荷收集效率，宜采用密度小的SiO₂作为钝化层；为了减少钝化层对倍增电子的复合进而提高电荷收集效率，宜降低钝化层厚度和提高入射电子能量；为了降低倍增电子扩散过程中载流子的复合进而提高电荷收集效率，宜降低P型基底的厚度和掺杂浓度。     

用于X射线探测器的非晶硒薄膜的制备及其性能的研究

非晶硒薄膜由于用在X射线数字平板探测器时有很高的灵敏度和分辨率,近年来一直是热门的研究课题。文中采用超高真空热蒸镀方法对如何制备出性能优良的非晶硒薄膜的方法进行了探讨,在严格控制蒸发室温度和基底温度的前提下,采用不同的蒸发电流和蒸发速率制备出不同的非晶硒薄膜,并对其进行了电阻测试和XRD分析以及耐高温测试。经过系列实验和结果分析,制备出了电阻率较高并有一定耐高温性能的非晶硒薄膜。     

非晶钛铝薄膜结构的RDF分析

非晶钛铝薄膜结构的ＲＤＦ分析王永瑞，邹　骐，刘震云，卢党吾（上海交通大学材料科学系，上海２０００３０）多年来，人们通过检测非晶、多晶薄膜的Ｘ射线衍射￣［１］或中子衍射呈径向对称分布的强度分布，导出其约化密度函数Ｇ（ｒ）和径向分布函数（ＲＤＦ），进而计...     

CdTe p—i—n薄膜太阳能电池热平衡态数值分析

通过应用Ｓｃｈａｒｆｅｔｔｅｒ－Ｇｕｍｍｅｌ解法数值求解Ｐｏｉｓｓｏｎ方程，对热平衡态ｐ（ＺｎＴｅ）／ｉ（ＣｄＴｅ）／ｎ（ＣｄＳ）薄膜太阳能电池进行计算机数值模拟。结果表明，ｐ（ＺｎＴｅ）／ｉ（ＣｄＴｅ）／ｎ（ＣｄＳ）的能带结构有利于光生载流子传输与收集，ＣｄＴｅ中高内建场提高了光生载流子通过有源区的输运能力，对ＣｄＴｅ进行适量Ｐ型掺杂还能提高其电池的短波收集效率。     

α—Fe2O3薄膜的制备,结构和气敏特性

采用等离子增强化学气相淀积工艺（ＰＥＣＶＤ）制备出了Ｆｅ２Ｏ３薄膜，用Ｘ射线衍射（ＸＲＤ）和扫描电子显微镜（ＳＥＭ）分析了薄膜的结构、表面形貌和粒度，研究了薄膜对乙醇、液化石油气、煤倔和氢气的敏感特性。结果表明所研制的薄膜对乙醇有较高灵敏度，共检测下限可达１ｐｐｍ，而对液化石油气、煤气和氢气不太敏感，具有优良的选择性。     

聚反式1,4-异戊二烯单晶非晶化过程的电子显微学研究

结晶聚合物如何从晶态转向非晶态一直是一个引人关注的问题。对于大尺寸的粉末状多晶，通常用小角Ｘ射线散射测量结晶部分和非晶部分厚度随温度的变化来分析可能的结晶熔融过程［１］，对于微米级小尺寸晶体，其非晶化至熔融过程还未见文献报道。本文对约２００ｎｍ大小的...     

基于镜像法的高层电梯内移动通信信号场强的仿真分析

为了加强移动设施建设的针对性，有效利用频率资源、提高网络质量，利用射线跟踪法对高楼电梯内单电梯与双电梯井道模型的移动通信场强传播进行仿真和分析。结果表明，对于单电梯井道，在全球移动通信系统（GSM）信号、3G和WiFi信号仿真结果与测量结果一致性良好；在4G和5G信号中，建议将天线间隔分别设置在9～12 m和8 m时较适宜。同时，双电梯井道在不同频段下场强分布仿真也得到了验证。通过建立无线传播仿真模型，为4G及5G通信系统的电梯覆盖提供了依据。     

室内环境中UWB MIMO传输下的电磁仿真

构建准确有效的超宽带（UWB）信号室内多发多收（MIMO）的电波传播模型对于设计UWB MIMO系统而言非常重要．本文采用时域射线跟踪算法，根据时域几何光学理论（GO）和一致性绕射理论（UTD），编制了三维电波传播仿真程序，并利用该程序进行了室内信道的仿真，得到了以下结论：室内环境中，采用双发射天线对深衰落情况有所改善，但双发射天线引起的快衰落现象比单发射天线严重；采用多径接收的方法可以改善室内信号的接收性能；使用垂直极化发射天线时，垂直极化接收的场强较强；发射天线放置在房间中部比房间一端时的信道空间相关性低，双发射天线比单发射天线时的信道空间相关性低。     

微晶/非晶Si∶ C∶ H半导体多层膜的结构研究

采用普通辉光放电分解硅烷的方法，沉积了具有交替微晶和非晶Ｓｉ∶Ｃ∶Ｈ亚层的多层膜样品。从喇曼散射结果分析，样品具有明显的微晶和非晶两相结构；在低角度Ｘ射线衍射谱中，观察到了多级的衍射峰，证明了多层结构的存在     

基于射线分裂的SBR新方法

提出了一种基于射线分裂的入射反弹射线方法（ＳＢＲ：Ｓｈｏｏｔｉｎｇ－ａｎｄ－Ｂｏｕｎｃｉｎｇ Ｒａｙ）以用于室内场强预测，与传统的ＳＢＲ方法相比，新方法对场强预测的精确度有一定的提高。     

An experimental X-ray image intensifier incorporating a channel electron multiplier plate

A channel electron multiplier plate has been used in an X-ray image intensifier to produce a full size distortion-free viewing system with sufficient image brightness to obviate the need for dark adaption. The useful diameter of the tube is 120 mm and the thickness is only a few centimeters. The characteristics of a channel plate are discussed and related to the requirements of an X-ray intensifier. Practical considerations such as field emission and gas desorption, which affect the design and performance of the tube, are also considered. The resolution capability is comparable with other X-ray image converters as it is primarily determined by the X-ray detecting layer. It is shown that the efficiency of this layer also determines the signal-to-noise ratio of the output picture and an expression is derived to show that a photocathode of only moderate sensitivity is adequate to reduce the effect of the exponential pulse height distribution of the channel plate output to negligible proportions. In addition to quantitative details of the tube performance a subjective assessment has been made relating the minimum visually perceptible detail with contrast for various X-ray dose rates.     

用于平响应X光探测器的复合滤片参数优化

在间接驱动的激光惯性约束聚变实验中,激光辐照产生的X射线能流的测量非常重要,它可以推测出黑腔的辐射温度和激光腔靶的耦合效率,一般通过平响应X射线探测器得到不同角分布的辐射流数据。通过对平响应复合滤片的结构参数进行优化设计,提高了平响应X射线探测器的测量精度。研究了复合滤片中薄金层、厚金层和孔面积比等结构参数对X射线探测器响应平整度的影响规律。从实验结果中可以得出:滤片和金阴极的标定数据和理论结果基本一致,并且薄金层的厚度对探测器整体响应的平整度起到主要作用,厚金层厚度和孔面积比影响较小,优化后探测器的平响应度达到5%,与理论设计相一致,此时的薄金层厚度、厚金层厚度和孔面积比分别为50 nm、380 nm和1:6.1。     

Generation and collection of photocarriers in dilute nitride GaInNAsSb solar cells

An improved photocurrent production is demonstrated in dilute nitride GaInNAsSb solar cells grown by molecular beam epitaxy. The photovoltaic properties were investigated by increasing the thickness of GaInNAsSb layers from 1.0 to 3.0 µm. The amount of photon absorption increased with increasing thickness. Yet an incomplete photocarrier collection was observed in the 2.0‐ and 3.0‐µm‐thick GaInNAsSb devices. This feature is due to a partial lack of electric field in the GaInNAsSb region. In order for complete carrier collection aided by the electric field, the background‐doping level should be as low as ~10¹⁴ cm⁻³ in a thick undoped‐GaInNAsSb absorption layer. Here, the effectiveness of annealing on improving the field‐assisted carrier collection is shown. This is ascribed to a decrease of the background doping in the GaInNAsSb layer. In a properly designed device for a 1.0‐eV GaInNAsSb cell, it is demonstrated that the external quantum efficiency can reach as high as 90% at wavelengths longer than the GaAs bandgap. Copyright © 2015 John Wiley & Sons, Ltd.     

Study of polycrystalline-Si thin-film transistors with different channel layer thickness at low bias voltage

A sub-micron poly-Si TFT device, operating at a drain bias of 1.5 V, has been studied with respect to channel layer thickness. A thinner channel layer may lead to better good gate control over the entire channel region, thus resulting in a lower threshold voltage. Similarly, under negative gate bias, a thinner channel layer would sustain larger vertical electric field. However, a thinned channel layer can reduce the source/drain bulk punch-through, thus causing a smaller channel region with relatively high electric field for carrier field emission. With using a low drain bias of 1.5 V, for the poly-Si TFT device with a thinner channel layer, the leakage current would be more effectively suppressed by the resultantly smaller channel region with relatively high electric field for carrier field emission. As a result, even for a gate length of 0.5 μm, the poly-Si TFT device with 20-nm channel layer can cause an off-state leakage of about 0.1 pA/μm at a drain bias of 1.5 V, and an on/off current ratio higher than 8 orders can be achieved.     

Transduction principles of a-Si:H Schottky diode X-ray imagesensors

This paper reports on the operating principles, along with design and fabrication considerations, of a novel direct conversion X-ray image sensor based on Mo/a-Si:H Schottky diodes. The choice of Mo as a Schottky contact follows from its relatively low intrinsic mechanical stress, temperature stability, and relatively large X-ray absorption. Furthermore, it is compatible with the standard a Si:H thin film transistor (TFT) technology. Here, the TFTs are intended for use as switching elements in large area imaging applications. Results of X-ray sensitivity are presented for a broad range of X-ray energies (20-100 keV), along with the influence of various geometric and operating parameters on X-ray sensitivity. The detector shows a linear response with respect to the number of absorbed X-ray photons. Analysis shows that the detector sensitivity reaches its maximum for a Mo layer thickness of around 500 nm at 60 kVp. Measurements, performed in a medical environment, demonstrate the feasibility of the detector for large area medical imaging applications     

一种基于石墨烯电场效应的软X射线探测器简

针对脉冲星导航对软X射线探测的实际要求,研究分析了一种基于石墨烯电场效应的软X射线探测器的性能.通过理论计算,并利用COMSOL Multiphysics有限元仿真软件,给出了探测器时间分辨率和能量分辨率的估值公式.在5.9 keV软X射线入射硅吸收层的情况下,时间分辨率的理论值可达7.2ns,能量分辨率的理论值约为90 eV(1.5％).结果表明,该探测器能够初步满足脉冲星软X射线的探测需求.     

Specific features of the luminescence and conductivity of zinc selenide on exposure to X-ray and optical excitation

The set of experimental data on the X-ray-excited luminescence and X-ray induced conductivity of ZnSe are compared to the data on the photoluminescence and photoconductivity. It is experimentally established that the current-voltage characteristics and the kinetics of phosphorescence and current relaxation depend on the type of excitation. It is found that the external electric field influences the intensity and shape of bands in the luminescence spectra. It is shown that the character of excitation defines the kinetics of recombination, charge carrier trapping, and conductivity in wide-gap semiconductors.     

Detailed evaluation of in-operando potentials in OLED devices: A combined experimental and drift-diffusion study

We report on a technique to determine in-operando transport properties of Organic Light Emitting Diodes (OLEDs). Two types of OLEDs that solely differ in the emission layer but obviously exhibit a different potential distribution are investigated in this study. If the emission layer consists of the isomer TH-A a large shift in onset voltage can be observed in case of layer thickness variation of the emission layer. In case of the isomer TH-B a thickness variation has no impact on the onset voltage. Therefore the voltage developments per layer are determined with the help of IV measurements on a set of devices with varying layer thickness. From an empirical point of view the voltage behaviour in each layer follows a simple power law. A drift-diffusion model is developed that well describes the current density dependent evolution of coefficient and exponent of the power law. From the model we are able to derive the carrier injection mechanism into the respective layer as well as the injection barrier height. Also the carrier mobility is determined. Finally we are able to show that the existence of a large injection barrier can not explain the observed onset voltage shifts in case of TH-A. Instead an electric field at or close to the interface is necessary to describe the TH-A behaviour.     

Organic thin film transistors with a SiO2/SiNx/SiO2 composite insulator layer

We have investigated a SiO₂/SiN_x/SiO₂ composite insulation layer structured gate dielectric for an organic thin film transistor（OTFT） with the purpose of improving the performance of the SiO₂ gate insulator. The SiO₂/SiN_x/SiO₂ composite insulation layer was prepared by magnetron sputtering.Compared with the same thickness of a SiO₂ insulation layer device,the SiO₂/SiN_x/SiO₂ composite insulation layer is an effective method of fabricating OTFT with improved electric characteristics and decreased leakage current.Electrical parameters such as carrier mobility by field effect measurement have been calculated.The performances of different insulating layer devices have been studied,and the results demonstrate that when the insulation layer thickness increases,the off-state current decreases.     

铌酸锂晶体结构对电场传感器灵敏度影响分析

铌酸锂晶体光学电场传感器为全介质结构,具有宽带宽、对被测电场干扰小的优点,但其灵敏度较低。因此,分析了晶体几何尺寸对传感器灵敏度的影响机理,得出通过增加沿外加电场方向的晶体尺寸同时减少晶体横截面上沿外加电场垂直方向的晶体尺寸来提高传感器的灵敏度。使用COMSOL仿真分析了铌酸锂晶体不同厚度、宽度、长度对晶体内部电场强度的影响,得出晶体厚度从15 mm减小到3 mm和宽度从3 mm增加到22 mm时,晶体内部电场强度分别提高约5.1倍和12.3倍;晶体长度从15 mm变化到55 mm时,晶体内部的电场强度变化仅约为5%。设计并研制出晶体尺寸分别为3 mm×3 mm×42.2 mm (x×y×z),3 mm×6 mm×42.2 mm (x×y×z),6 mm×6 mm×42.2 mm(x×y×z)的三只铌酸锂晶体电场传感器,并搭建工频电场测试平台,测试得出三只电场传感器的灵敏度分别为0.243 mV/(kV·m^-1)、0.758 mV/(kV·m^-1)、0.150 mV/(kV·m^-1)。当晶体厚度和长度一定且晶体宽度从3 ...