高积分光电灵敏度多层Be浓度掺杂的GaAs负电子亲和势光电阴极

研究了变掺杂浓度结构对GaAs负电子亲和势光电阴极积分光电灵敏度的影响.通过MBE生长了两组GaAs同质外延样品.其中一组采用了均匀掺杂的单层结构,Be掺杂浓度为1×1019cm-3;另一组采用了变掺杂的多层结构,从衬底开始Be的掺杂浓度依次为1×1019,7×1018,4×1018和1×1018cm-3.负电子亲和势光电阴极通过在高真空系统中交替通入Cs和O激活得到.在线光谱响应测试曲线表明,多层Be掺杂结构光阴极的积分光电灵敏度比单层Be掺杂结构光阴极的积分光电灵敏度至少提高了50%.两种结构的GaAs样品表现出不同的表面应力情况.     

透射式GaAs光阴极量子效率分析

通过对透射式ＧａＡｓ光阴极“三物理过程”的描述和理论分析，指出了影响量子效率的不利因素，讨论和提出了克服，消除这些不利因素的方法，措施和途径。     

国外GaAs光电阴极光谱响应特性比较与分析

对国外标准三代、高性能三代、超三代和四代GaAs光电阴极进行了光谱响应曲线比较.结果显示,GaAs光电阴极的积分灵敏度、响应的截止波长、峰值响应和峰值位置存在明显差异.曲线拟合结果表明国外GaAs光电阴极的后界面复合速率较低,表面逸出几率和电子扩散长度从标准三代到四代不断提高,这些性能的改善导致了GaAs光电阴极灵敏度的提高.     

指数掺杂透射式GaAs光电阴极表面光电压谱研究

通过求解一维稳态少数载流子扩散方程,推导了指数掺杂和均匀掺杂的透射式GaAs光电阴极表面光电压谱理论方程。利用金属有机化学气相沉积(MOCVD)外延生长了发射层厚度相同、掺杂结构不同的两款透射式阴极材料。通过表面光电压谱实验测试和理论拟合发现指数掺杂结构在发射层厚度和后界面复合速率相同的情况下能够有效提高阴极电子扩散长度,这主要由于内建电场能够促使光生电子通过扩散和电场漂移两种方式向表面运动,从而最终提升阴极的发射效率和表面光电压谱。利用能带计算公式和电子散射理论对这两种不同结构材料的表面光电压谱进行了详细分析。     

GaAs：Gs—O NEA光电阴极电子表面逸出几率的计算

介绍了计算CaAs:Cs-O NEA光电阴极电子表面逸出几率的方法，选用双偶极层表面模型，计算了两个极层形成的界面势垒各自对电子表面逸出几率的影响，提出了增大电子表面逸出几率的条件，并粗略推测了第一偶极层的厚度。     

多层金属-介质镀膜光栅的聚焦特性

结合等离子金属光栅原理和多层膜理论,提出一种金属-介质-金属多层光栅结构以增强透射光的聚焦效应。利用时域有限差分(FDTD)法对该多层结构的聚焦特性进行模拟仿真,得到多层结构的聚焦特性随金属-介质膜层数和凹槽数目的变化特性。结果表明,通过控制金属-介质层层数或者凹槽数目,焦距明显改善,焦距可达9.15μm,最大焦深约为26.38μm,相对于传统金属光栅,聚焦效应得到了明显增强。     

铁电多层畴结构中铁电畴层波振动模式的频谱分析

本文首次对多层畴结构中的振动模式进行了实验研究,观察到了一系列大小相当的中心峰,这对应于不同中心同步频率下激发的不同的振动模。通过频谱分析,获得了3,4,5层畴层结构的色散曲线。     

MMIC用多层磁膜电感研究

采用磁控溅射生长磁膜工艺,结合BCB(苯并环丁烯)平坦化技术,首次制作了"金属线圈/磁膜/金属线圈(M/F/M)"和"磁膜/金属线圈/磁膜/金属线圈(F/M/F/M)"两种结构的多层磁膜电感,整个工艺与标准MMIC工艺兼容.在2 GHz处,"金属线圈/磁膜/金属线圈"结构电感的电感量为7.5 nH,品质因数为7.17,...     

多层结构红色OLED器件的制备与光电性能研究

采用真空热蒸镀的方法,在高精度膜厚控制仪的监控下,实现了有机薄膜功能材料的精确蒸镀,其中发光层采用三种材料的共蒸,制备了一种多层结构红色有机电致发光(OLED)器件:ITO/CuPc/α-NPD/Alq3∶Rubrene(10%)∶DCJTB(1%)/Alq3/LiF/Al.从实验结果分析可知:随着驱动电压的变化,其EL光谱有蓝移的现象,发射峰从638nm变到632nm,同时色坐标值也发生相应的变化;器件的发光效率在驱动电压较低时(5V),达到最大值5.77cd/A,随着驱动电压的增加,发光效率呈缓慢降低的趋势.     

大面积高密度多层厚膜表面组装件的研制

介绍了研制大面积高密度多层厚膜表面组装件的概况及组装设计与制造工艺上所采取的措施。该组装件尺寸为９５ｍｍ×６７ｍｍ×１ｍｍ，布线密度为１２．５根／ｃｍ，介质通孔密度７．８个／ｃｍ２，元器件总数为１２２只，显示了该组装件的组装工艺水平。     

Design of Novel Compact Electromagnetic Bandgap Structures with Enhanced Bandwidth

Two kinds of compact electromagnetic band gap （EBG） structures are designed. A two layer compact EBG structure configured with cross spiral shape line inductors and interdigital capacitors is first presented. Because of its significantly enlarged equivalent inductor and capacitance, the period of the lattice is approximately 4.5% of the free space wavelength. By insetting several narrow slits in the ground plane, the bandwidth of the main bandgap is enhanced by nearly 19%. Further effort has been made for designing a three layer compact EBG structure. Simulation results show that its period is reduced by about 26% compared to that of proposed two layer EBG structure, and the bandwidth of the main bandgap is about 3 times as that of the proposed two layer EBG structure. The detailed designs including a two layer compact 3×7 EBG array with and without defect ground plane and the three layer EBG array are given and simulation results are presented.     

Multilayer Graphene with a Rippled Structure as a Spacer for Improving Plasmonic Coupling

The plasmonic coupling, the enhanced electromagnetic field occurring through a uniform and small separation between metallic particles, is required for better application to localized surface plasmon resonance. Graphene has been studied as a good spacer candidate because of its precise controllability at subnanoscale. Here, the enhancement of plasmonic coupling among metallic nanoparticles (NPs) uniformly spread out on both sides of a graphene spacer is experimentally and simulatively investigated. Additionally, the post‐evaporated flat structure is rippled along one direction to reduce the separation between nanoparticles. As the amount of rippling increases, the enhancement factor (EF) of the plasmonic coupling increases almost linearly or quadratically depending on the size of nanoparticles. Such a highly rippled nanostructure is believed to not only increase the plasmonic coupling in either side of the spacer but lead to a higher density of “hot spots” through the spacer gap also. The observed EFs of a structure with the MLG spacer are consistent with the simulation results obtained from the classical electrodynamics. On the other hand, the SLG case appears to be inconsistent with such a classical approach, indicating that the plasmon tunneling through the thin barrier is prevalent in the case of the SLG spacer.     

表面钝化硅纳米线的能带结构

采用第一性原理的方法计算了不同尺寸的(100)硅纳米线在H饱和及F饱和下的电子结构.计算结果表明,F饱和与H饱和的(100)硅纳米线均为直接禁带半导体,但F饱和硅纳米线的禁带宽度和价带有效质量都远小于H饱和硅纳米线,这一现象可用价带顶的σ-n杂化效应来解释.计算结果还表明,H或F饱和的(100)硅纳米线的极限--硅单原子链则表现为间接带隙半导体,文中对这一现象进行了分析和讨论.