覆膜浸渍扩散阴极表面微区电子发射像研究

覆膜对浸渍扩散热阴极表面电子发射的影响一直是热阴极研究领域的重点课题。该文采用最新研制的深紫外激光光发射电子显微镜/热发射电子显微镜(DUV-PEEM/TEEM),对一半覆膜、另一半未覆膜的浸渍扩散阴极试样作了1150 ℃×2 h激活,并对其表面微区的热电子发射像及其随温度的变化作了比较。结果发现,两种阴极的热电子发射均主要位于孔隙及其邻近颗粒边缘;随温度升高,未覆膜阴极发射主要集中于孔隙内及周边有限区域内,发射面积增量较小,覆膜则使阴极有效发射区域得以由孔隙及其边缘向距孔隙更远的区域延伸,发射面积大幅增加。上述结果首次给出了覆膜浸渍扩散阴极微区的电子发射特征,对于理解该类型阴极发射机理有一定参考价值。     

碳纳米管场发射器件新型阴极的研究

碳纳米管场发射显示器件（CNT-FFDs）中阴极的制备和表面处理一直是其中的关键环节而备受关注,本文通过光刻技术、丝网印刷技术、表面超声等流程制作带有平整电阻层的发射阴极,并对该阴极进行场发射测试,并通过扫描电镜（SEM）照片分析阴极表面,发现开启电场、发射均匀性及电流稳定性比以前未加处理的阴极有很大程度上的改善。此法适合于大面积的碳纳米管场发射显示的阴极制作。     

激光法制备超细纳米金刚石的相变机理

为了研究激光法制备纳米金刚石的相变机理,采用纳秒脉冲激光冲击微米级石墨悬浮液,并做强酸高温氧化提纯处理,结合X射线衍射、喇曼光谱、高分辨率透射电镜等表征手段以及热力学和动力学分析方法,对实验结果进行了理论分析和实验验证。合成得到分散均匀、尺寸在4nm~12nm的超细纳米金刚石。结果表明,纳秒激光辐照下,石墨是通过固态-气态-液态-固态的形式转变为金刚石结构的;与毫秒脉冲激光相比,高功率密度、短脉宽的纳秒激光为金刚石核的生长提供了大的过冷度,提高了金刚石的形核率和生长速率;但是纳米金刚石的生长温度范围极小,冷却过程中石墨结构与金刚石结构同时形核、长大,引起金刚石颗粒表面的石墨化,限制了纳米金刚石的生长。     

应用于FED的金刚石薄膜的光学和结构分析

本文比较研究了不同晶粒大小和结构的金刚石薄膜的场发射性质,这些金刚石薄膜通过热丝辅助化学气相沉积法(HFCVD)获得.研究结果表明纳米尺寸效应对金刚石薄膜的场发射性能有非常重要的影响,通过比较不同晶粒尺寸的金刚石薄膜发现纳米金刚石薄膜相对于大晶粒金刚石薄膜(比如微米级的金刚石薄膜)有更好的场发射性能.从拉曼光谱得到,含有一定量非金刚石相的金刚石薄膜有更好的场发射能力和更低的开启电场(E0).另外,具有(111)定向的金刚石薄膜比起其他结构的金刚石薄膜,它的电子发射能力更强.     

碳纳米管蒸发特性及其对场发射性能的影响

为了探究场发射阴极电流的跌落机制,采用四极质谱仪分析的方法研究高温蒸发对阴极场发射性能的影响。实验结果表明：碳纳米管阴极在1173 K以上温度时开始蒸发出碳;在1373 K高温下连续蒸发100小时,碳纳米管阴极的开启场强增加21.7%,阈值场强增加31.7%,增强因子减小16.2%,功函数增加11.9%。扫描电镜（SEM）和能量色散X射线光谱仪（EDX）分析显示：增大的功函数和减小的场增强因子降低了阴极的场发射性能。阴极材料的蒸发是阴极电流跌落的重要原因。     

Two-dimensional simulation of silicon avalanche cathodes

The characteristics of silicon avalanche cathode as a novel electron emitting device with ultra-shallow p-n junctions have been studied using the two-dimensional device simulator PISCES-IIB. The steady-state simulation indicates that the nonplanar surface topology resulting from fabrication process causes current crowding near the edge of the emitting area where the surface step exists. Current crowding degrades the emission uniformity and also reduces the emission current under increased reverse bias. The nonplanar surface structure also causes punchthrough in the epitaxial layer as the reverse bias on the cathode increases. As a result, the percentage of the cathode current contributing to emission decreases, reducing the emission efficiency consequently. The simulation shows that the portion of the cathode current that flows through the emitting area drops to as much as 30% at cathode bias higher than 12 V, compared to the same current just after breakdown. This also affects the rate of increase in the total emission current which is the product of the emission efficiency and the overall cathode current     

分段圆型碳纳米管阴极结构的三极FED制作

利用钠钙平板玻璃形成阴极板;结合丝网印刷技术在阴极板上制作了分段圆型碳纳米管阴极结构。烧结固化的银浆层用于分别构成矩形底电极和圆型底电极,其良好的导电性能确保阴极电势能够被顺利传导给碳纳米管。对矩形底电极采取了分段条形电极形式,多个分段条形电极整体排列在阴极板表面,形成分段条形电极矩阵,改进的矩形底电极能够有效降低整体显示器的无效电压降;而制作的圆型碳纳米管层和圆型底电极用于提高碳纳米管的场发射性能。结合分段圆型碳纳米管阴极,研制了三极结构的场致发射显示器。该显示器具有良好的场致发射特性和高的图像发光亮度,能够正确显示简单的字符图像,其开启场强为2.16 V/μm。     

碳纳米管冷阴极Pierce电子枪

为发展场致发射冷阴极毫米波电真空辐射源器件, 对利用大面积碳纳米管冷阴极产生大电流、高电流密度电子注的电子光学系统进行了研究.通过在Pierce电子枪阴极表面引入栅网结构, 解决了碳纳米管冷阴极场致发射所需的强电场和电子聚束问题.在碳纳米管冷阴极实验测试数据的基础上, 采用粒子模拟软件对上述电子光学系统进行了仿真.研究了栅网对注电流、注腰半径和电子注散射的影响, 分析了阳极电压和外加轴向磁场对电子注的聚束作用.优化后的仿真结果表明在阴极发射面为3.03 cm2时, 该电子光学系统能够产生210 mA、60 kV, 电流密度为6.7 A/cm2, 最大注半径为1mm的电子注.     

可印制碳纳米管冷阴极中碳纳米管含量的优化

采用丝网印刷法制备了不同碳纳米管含量的冷阴极.研究了不同碳纳米管含量的冷阴极的场发射特性与其微结构和电学特性的关系.实验发现,碳纳米管冷阴极的导电性和场发射特性受碳纳米管含量影响,具有适当的碳纳米管含量的冷阴极的场发射特性最佳.     

FED显示驱动电路结构及其场发射特性分析

从场发射的基本原理出发,分析了影响场发射电流的内外因素。阴极表面强电场是产 生发射电流的必要条件,但像素的不均匀性和场发射特性的非线性导致无法产生精确的发射电流,由此带来了亮度调节的可控性差;阴极驱动电路作为发射电流回路的一部分,其电路结构直接影响发射电流的控制特性,分析表明电流驱动模式能对阳极束电流进行精确控制,是实现FED亮度控制的理想驱动方式。     

纳米多孔硅的场致电子发射性能研究

对采用阳极氧化法及阴极还原表面处理技术制备的性能稳定的纳米多孔硅,用原子力显微镜(AFM)表征了其微观结构,多孔硅颗粒粒径在30 nm左右.室温条件下测试了多孔硅场电子发射的特性,结果表明,多孔硅具有很好的场致发光性能,在5 V/μm的电场下就可以产生场发射电流.多孔硅的开启电压在1 000 V左右,发射电流随着电压的增大而不断增大,发射电压在2 000 V以上.

Abstract：

Nanoscale porous silicon (PS) was prepared by anodic oxidation, cathode reduction and surface treatment technique. The porous silicon particles with the average diameter of about 30 nm were obtained by characterizing their microstructure with atomic force microscope (AFM). Electron field emission characteristics of porous silicon were investigated at room temperature. The resuhs demonstrate that porous silicon has favorable electroluminescence properties, and the field emission current can be generated only under the electric field of 5 V/ μm. And the turn - on voltage is about 1 000 V. With the increase of the offered voltage, the emission current is enhanced and the emission voltage is over 2 000 V.     

EMISSION AND SURFACE CHARACTERISTICS OF A DISPENSER CATHODE COATED WITH RHENIUM

The emission and surface characteristics of a dispenser cathode coated with Re arestudied.It is found that the dispenser cathode coated with Re has both higher current densityand more uniform distribution of emission than the S-type cathode.The Auger images of Bashow that the Ba distribution on the surface of the cathode coated with Re is more uniform thanthat on the surface of the S-type cathode.The analytical results by XPS and low energy AESshow that the Ba on the surface of the cathode coated with Re has stronger metallic propertythan that on the surface of the S type cathode.     

一种贮存式氧化物阴极

该文论述了一种新的贮存式氧化物阴极。这种阴极的直流发射、脉冲发射和阴极寿命性能都比普通氧化物阴极好。文中对阴极发射材料的形貌、贮存活性物质的结构进行了分析,观察了阴极镍网表面电子发射图像,讨论了阴极发射机理。     

复铼膜阴极的发射和表面特性

本文报道了复铼膜扩散阴极的发射和表面特性的研究结果,并与S-型阴极进行了比较。实验结果表明:S-型阴极复铼膜后,其热电子发射明显提高,且分布均匀。月极表面上主要元素的俄歇像显示Ba在复铼膜阴极表面上的分布要比在S-型阴极表面上均匀得多,Ba的低能Auger谱和XPS的研究表明:与S-型阴极相比Ba在复铼膜阴极表面上呈现更强的金属特性。这可能是S-型阴极复铼膜后发射增大的主要原因。     

待定系数法计算场致发射体阴极表面场强和发射电流密度

在计算场致发射体阴极发射电流时 ,影响发射电流的主要因素是阴极表面的电场强度。由于发射电流密度的大小和阴极表面场强呈指数关系 ,阴极表面场强很小的变化将引起发射电流的剧烈变化 ,所以提高阴极表面场强的计算精度是至关重要的。本文提出了一种计算阴极表面场强的新方法——待定系数法 ,并用该方法计算了一个二极管场致发射体的阴极表面电场强度和电流密度。     

电泳法制备石墨烯场发射阴极的性能研究

电泳法制备的石墨烯阴极由于其独特的优势,目前已经成为石墨烯阴极的主要制备方法。因此,研究电泳电流以及电泳浓度对石墨烯阴极表面形貌和发射性能的影响具有十分重大的意义。通过扫描电镜、拉曼光谱和超高真空测试平台对其进行形貌和性能表征。结果表明,电泳浓度和电泳电流均对石墨烯阴极的表面形貌和发射性能有较大影响。在电泳电流为4mA,电泳液中石墨烯与异丙醇的比例为110mg：200ml时,其发射性能最佳,开启场强约为4.7V/um。     

Lateral field emission diodes using SIMOX wafer

Lateral field emission diodes were fabricated by using separation by implantation of oxygen (SIMOX) wafer and their current-voltage characteristics (I-V) were analyzed. Applying conventional photolithography and local oxidation of silicon (LOGOS) process, we fabricated single-crystalline lateral silicon field emitters with very sharp cathode and anode tips and very short cathode to anode spacing ranging from 0.3 to 0.8 μm as well. Two different types of tips, tapered and wedge-shaped emitters, were typically formed according to oxidation time. The turn-on voltages for both types of diodes were as low as 22~25 V and the emission currents were as high as 6 μA/tip at voltages of 35~38 V. From the Fowler-Nordheim (FN) equation, field emitting area (A) and field enhancement factor (β) for both types of diodes were estimated to explain the low turn-on voltages and the high emission currents     

A physical simulation model for field emission triode

A simple but accurate physical model, which can be incorporated into circuit simulation programs such as SPICE for the field emission triode (FET), is developed. The model is based on the Fowler-Nordheim (F-N) current density-electric field (J-E) relationship. An electric field form is adopted to calculate the current density distribution along the surface of the sphere-shape tip. The cathode current is obtained by integration of the current density over the emission surface. The gate current is derived by the same integration, but over part of the emission area. A procedure to extract the values for the parameters of the model is also given. The model and the procedure has been applied to experimental devices to demonstrate its accuracy     

电泳沉积纳米金刚石涂层场发射阴极工艺研究

采用电泳沉积(EPD)制备薄膜的方法,在金属钛片上均匀地涂覆纳米金刚石涂层,经真空热处理,制成场发射阴极.该文主要研究了不同的电泳液配方、电泳电压及电泳时间对涂层制备的影响.实验结果表明,粘度系数较大的电泳液及较低的电泳电压下适当延长电泳时间有利于改善涂层的均匀性和致密性;典型样品开启电场为5.5 V/μm,在20 V/μm场强下的电流密度达到169 μA/cm~2.发光测试表明,发光点密度较大且均匀分布,发光稳定,亮度较高.用X-射线衍射(XRD)和扫描电子显微镜(SEM)对样品的成份及形貌进行了分析,结合其场发射测试结果,解释了样品性能的差异和变化.     

类石墨薄膜的场致电子发射研究

利用脉冲激光烧蚀技术在硅衬底上制备了类石墨薄膜，以该薄膜为阴极进行了场致电子发射实验。当在阴阳极之间加电场后，两极之间出现了放电现象。放电之后．类石墨薄膜的阈值电场大大降低了．当电场为20V／μm时．该薄膜的发射点密度可以达到10^6/cm^2。利用Raman光谱、扫描电镜和X射线光电子谱对薄膜的表面形貌和微结构进行了测试．薄膜中的类石墨微结构对该薄膜的场致电子发射特性起了促进作用．场致电子发射实验显示类石墨薄膜作为冷阴极电子材料具有潜在的应用价值。