后栅结构四针状纳米ZnO场致发射显示器的研制

为了解决二极结构FED驱动电压高的问题,设计制作了后栅式三极结构纳米ZnO场致发射显示器,进行了场致发射实验,验证这种结构的可行性。采用丝网印刷厚膜技术实现后栅极结构FED的制作,工艺简单,实现了较低电压的调制。对影响场致发射性能的栅极电压、阳极电压进行了分析讨论。将阴栅极板和荧光屏封装成5英寸三极结构的场致发射显示器,实现了稳定的场致电子发光显示。     

三极结构四针状纳米ZnO场致发射显示器的研究

针对二极式场致发射显示器(field emission display, FED)驱动电压过高的问题, 设计制作了前栅极式三极结构纳米ZnO场致发射显示器, 并进行了场致发射实验, 验证这种结构的可行性.前栅极结构采用喷砂工艺结合光刻技术, 制作出微细的栅孔结构, 实现了较低电压的控制.同时对影响场致发射性能的栅极电压、栅孔开口尺寸和介质层厚度进行了分析讨论.实验结果表明:采用三极结构四针状纳米ZnO场致发射显示器具有良好的发射性能, 是一种有前途的场致发射显示器.     

平行栅结构氧化锌场致发射显示器的研制

用陈化处理过的锌粉为原料,采用高温气相氧化法制备四针状氧化锌材料。应用厚膜、光刻工艺和丝网印刷法制作氧化锌场发射阴极阵列。将阴极板与阳极荧光板制成了5英寸(12.7 cm)单色平行栅结构场致发射显示器(FED)并对其进行了场发射性能测试。分析讨论了影响发射性能的栅极电压、阳极电压以及阴极厚度等参数。该FED在约4000 V阳极电压和300 V栅极电压的驱动下能实现全屏发光。实验结果表明,氧化锌平行栅结构FED具有良好的栅极调控作用,场致发射性能良好,具有良好的应用前景。     

器件参量对栅极调制碳纳米管冷阴极的影响(英文)

基于电场叠加原理,利用悬浮球模型给出了带栅极纳米管顶端电场与电场增强因子,分析了碳纳米管与衬底之间的接触电阻、器件几何参量以及阴栅极之间的电介质对器件场发射性能的影响.结果表明:接触电阻大大降低了碳纳米管阴极的场发射电流,当接触电阻超过100kΩ时,发射电流密度非常小,此时需要更高的阳极开启电压;当阴栅极之间的电介质为真空时,阴极电子发射性能最佳;除了碳纳米管的长径比之外,栅孔半径、阴栅极间距以及阳极距离等的优化设计,也能提高器件发射性能;通过栅极偏压的调制,可以降低阳极驱动电压.     

太赫兹源场致发射电子源

通过粒子模拟(PIC)软件模拟计算了在ps级别下二极与三极结构碳纳米管场致发射的电流密度与电子注聚焦性能。阳极电压在2 kV时,二极结构下电流密度达到1.85 A/cm2;三极结构下,栅压700 V时发射电流密度达到2.3 A/cm2,且在一定的三极结构参数与电极电压下,可以获得较好的电子注聚束效果。通过碳纳米管二极管发射实验,获得了6.6 A/cm2的发射电流密度,总发射电流达到52.1 mA,可以为太赫兹器件提供连续发射的电子注。     

增强碳纳米管场发射性能的沟槽形冷阴极制作(英文)

基于烧结工艺和丝网印刷技术,研发了一种新的沟槽形冷阴极.底部绝缘层由黑色绝缘浆料被烧结后制成,且在底部绝缘层中存在倾斜面.将银浆丝网印刷在条形电极上,依次经烘烤和烧结工艺后形成银电极.利用细砂纸,对银电极进行适当的抛光工艺,以便获得光滑的电极表面.由于特有的银电极形状,从而易于获得更大的场增强因子.将碳纳米管制备在银电极上,形成场发射极.致密的碳纳米管层完全覆盖银电极表面,特有的边缘场增强效应能够使得碳纳米管发射出更多的电子.顶部绝缘层则用于抑制碳纳米管的横向电子发射.结合沟槽形冷阴极,制作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及优良的发光图像均匀性.与普通冷阴极场致发射显示器相比,沟槽形冷阴极场致发射显示器能够将开启电场从1.86V/μm降低到1.78V/μm,将最大场致发射电流从1 537μA增加到2 863μA,且将最大发光图像亮度从1 386cd/m2提高到1 865cd/m2.该制作技术在场致发射显示器中具有较强的实际应用性.     

三极场发射显示器中二次印刷型碳纳米管阴极的制备及特性(英文)

结合丝网印刷技术,研发了一种碳纳米管阴极制备法.利用双壁纳米管作为原材料,并加入细小银颗粒,制作了混合纳米管浆料.将混合纳米管浆料制作在传导电极表面,再将普通纳米管浆料印刷在混合纳米管浆料的上面.在链式烧结炉中对烘烤后的纳米管浆料同时进行烧结以除掉有机溶剂.在进行适当的后处理工艺之后,就形成了二次印刷型纳米管阴极,它能显著改善阴极的场致发射特性.制作了二次印刷型纳米管阴极的三极结构场致发射显示器.该显示器具有更高的发光亮度以及更好的发光图像亮度均匀性.与普通纳米管阴极场致发射显示器相比较,它能够将开启电场从2.15V/μm降低到1.75V/μm,并能够将最大场发射电流从735.8μA提高到1 588.5μA.所研发的纳米管阴极制备方法具有很强的实际应用性,且制作成本低廉.     

氮气火花开关击穿机制的理论和数值研究

三电极气体火花开关带有触发极,相比两电极开关,其开关导通的可控性较高,工作电压较低且抖动小,所以气体火花开关中三电极开关的应用较为广泛.本文针对大气压氮气环境下的两电极开关和三电极开关的击穿机制进行了理论与数值模拟研究.通过理论和数值计算发现,对于平板-平板的两电极开关来说,低电压下(小于6.3 kV)无法产生流注击穿,高电压下(大于6.3 kV)会先形成由阴极到阳极的负流注,然后再形成由阳极向阴极的正流注.而在三电极开关的击穿过程中,首先会在触发极和绝缘体之间发生击穿,然后这个通道不断向阴阳极扩展,最终形成阴阳极之间的电弧通道.在本文的计算工况下,如果需要阴极-触发极、阳极-触发极同时击穿的话,其阴极-触发极之间的外加电压需要大于1.18 kV,而阳极-触发极之间的外加电压需要大于3 kV.当考虑触发极的场致发射后,该击穿阈值可以显著降低.     

基于碳纳米管场发射三电极显示器的设计和实验

提出了一种基于碳纳米管场发射三电极大面积全彩色平板显示器模型,其特点是栅极和阴极在同一个平面上,驱动电压低,而电子传输比可以高达29.3%(达到阳极的电子与从阴极碳管上发射出来的电子之比),实验结果和理论模拟的结果符合得很好.阴极和栅极之间的沟槽可以用激光打标机刻蚀形成,用做阴极发射体的碳纳米管浆料用水浴法形成,显示器制作工艺简单.     

低压荧光数字显示器

结构 基本结构类似三极管,由直热式阴极、控制栅极和拚凑式阳极组成。为了不干扰显示,阴极和栅极都用极细的材料制成,阳极则是安装在一块陶瓷的基板上,这些阳极上涂以荧光物质。在多位数字显示器件中,动态驱动(脉冲驱动)系统是外加的。整个显示器各位数字中的同一段都相互联接在一条线上。不论显示单元多少,大多数显示器只用一条或两条灯丝。用玻管、玻板或金属容器为外壳。 工作原理 如图1所示,包复氧化物(BaO)的灯丝放出热电子。在栅极和阳极上加上几伏(或更大)的电压,以提供相对于灯丝(阴     

Integration of ZnO nanowires in gated field emitter arrays for large-area vacuum microelectronics applications

Addressable field emitter arrays (FEAs) have important applications in vacuum electronic devices. However, it is important to integrate nanowire emitters into a gated structure without influencing the device structure and maintain the excellent field emission properties of nanowire emitters in the FEAs after the fabrication process. In this study, gate-structure ZnO nanowire FEAs were fabricated by a microfabrication process. The structure combines a planar gate and an under-gate, which is compatible with the preparation of ZnO nanowire emitters. The effect of electrode materials on the field emission properties of ZnO nanowires was studied using a diode structure, and it was found that ZnO nanowire pads on indium-tin-oxide (ITO) electrode showed better field emission performance compared with chromium (Cr) electrode. In addition, effective emission current modulation by the gate voltage was achieved and the addressing capability was demonstrated by integrating the ZnO nanowire FEAs in a vacuum-encapsulated field emission display. The reported technique could be a promising route to achieve large area addressable FEAs.     

Fabrication and properties of film-under-gate field emission arrays with SnO2 emitters for flat lamp

The film-under-gate field emission arrays (FEAs) have been fabricated on the glass substrates by conventional photolithography, anodic oxidation and lift-off method. SnO₂ emitters were deposited on the cathode electrodes of under-gate triode by screen printing. The image of film-under-gate field emission arrays with SnO₂ emitters was measured by the optical microscopy and field emission scanning electron microscopy (FESEM). The electric field distributions and electron trajectories of film-under-gate triode were simulated in the same anode voltage and different gate voltage by ANSYS. I-V characteristics of film-under-gate triode with SnO₂ emitters were investigated. It indicated that the SnO₂ emitters by screen printing uniformly distributed on the surface of cathode electrodes. The maximum anode current in this triode structure could come to 385 μA and the highest lightness was approximately 270 cd/m² as the gate and anode voltage was 140 V and 2000 V, respectively, at the anode-cathode spacing of 1100 μm. Moreover, the emission current fluctuation was less than 5% for 8 h. It showed that the fabricated device has a good stability of field emission performance and long lifetime, which may lead to practical applications for field emission electron source based on flat lamp for back light units (BLUs) in liquid crystal display (LCD).     

激光烧蚀对碳纳米管薄膜场发射性能的影响

采用丝网印刷工艺制作了碳纳米管(CNTs)薄膜阴极.经适当能量激光烧蚀后,相互粘连的CNTs随表面粘附有机物的蒸发而分散开,管间隙增加、屏蔽效应减小,使得场发射性能大幅度提高,开启场强降低、场倍增因子β增大.Raman光谱分析表明,随激光能量增加,CNTs表面缺陷增多,成为新的场发射点,对其β增大的贡献加强.相对于两电极结构,三电极中平栅极结构场发射性能经激光烧蚀有更显著的改善.这说明激光烧蚀是提高CNTs场发射性能的有效方法. 关键词： 碳纳米管薄膜 场发射 激光烧蚀 Raman光谱     

An improved planar-gate triode with CNTs field emitters by electrophoretic deposition

An improved planar-gate triode with carbon nanotubes (CNTs) field emitters has been successfully fabricated by conventional photolithography, screen printing and electrophoretic deposition (EPD). In this structure, cathode electrodes and ITO arrays linked with gate electrodes were interdigitated and paralleled on the same plane although the gate electrodes and cathode electrodes were isolated by dielectric layer, a so-called improved planar-gate triode structure. An electrophoretic process was developed to selectively deposit CNTs field emitters onto cathode electrodes in the CNTs suspension by an applied voltage between the gate electrodes and cathode electrodes. The optical microscopy and FESEM image showed that the CNTs emitters with the uniform packing density were selectively defined onto the cathode electrodes. In addition, field emission characteristics of an improved planar-gate triode with CNTs field emitters were investigated. The experiment results indicated that the turn-on voltage of this triode structure at current density of 1 μA/cm² was approximately 55 V. The anode current and gate current came to 396 μA and 325 μA, at gate voltage and anode voltage of 100 V and 4000 V, respectively and at the anode-cathode spacing of 2000 μm. The emission image became brighter and the luminous image with dot matrix on the anode plate obviously increased with the increase of the gate voltage. Moreover, the emission current fluctuation was smaller than 5% for 11 h, which indicated that the improved planar-gate triode has a good field emission performance and long lifetime.     

氧化锌纳米线的紫外光耦合增强场电子发射特性

本文采用热化学气相沉积方法制备氧化锌纳米线阵列, 研究氧化锌纳米线阵列在紫外光辐照下的场电子发射特性. 实验结果表明, 在紫外光辐照下, 氧化锌纳米线场发射开启电压降低, 发射电流明显增大. 机理分析认为, 氧化锌纳米线紫外光增强的场发射源自场电子发射与半导体耦合作用, 紫外光激发价带电子跃迁到导带和缺陷能级使发射电子数量增加, 同时, 光生电子发射降低了发射材料表面的有效功函数, 从而显著增强场电子发射性能. 氧化锌纳米线具有紫外光耦合增强场电子发射特性, 在光传感、冷阴极平板显示和场发射电子源等方面具有潜在的应用价值.     

Field emission characteristic of screen-printed carbon nanotube cathode

The fabrication of carbon nanotube emitters with excellent emission properties is described. The multi-walled carbon nanotubes (MWNTs) produced by chemical vapor deposition (CVD) method were purified with oxidation method and mixed with organic binding pastes and then screen-printed on glass substrates with ITO film. We applied anode voltage gradually to refine the emission behavior of the emitter by cleaning the top surface of screen-printed carbon nanotubes (CNTs). The density of the carbon nanotubes is about 2.5×10⁸/cm². Diode field emission experiments were performed in dynamic vacuum system to study the emission current, the emission uniformity, etc. Bright and stable character emission images were obtained in the diode structure and the emission current could approach 1 mA/cm².     

Electron field emission properties of conducting polymer coated multi walled carbon nanotubes

The present work describes the field emission characteristics of conducting polymer coated multi walled carbon nanotubes (MWNTs) field emitters fabricated over flexible graphitized carbon cloth. Nanocomposites involving the combination of MWNTs and conducting polymers polyaniline (PANI) and polypyrrole (PPy) have been prepared by in-situ polymerization method and have been characterized using scanning electron microscopy and transmission electron microscopy. Using spin coating method, field emitters based on PANI/MWNTs and PPy/MWNTs over flexible graphitized carbon cloth have been prepared. The field emission characteristics have been studied using an indigenously fabricated set up in a vacuum chamber with a base pressure of 2 × 10⁻⁵ Pa and the results are discussed. Our results display that the field emission performance of the emitters depends strongly on the work function of the emitting material. Low turn on emission field of 2.12 V/μm at 10 μA/cm² and high emission current density of 1 mA/cm² at 3.04 V/μm have been observed for PANI/MWNTs field emitter.     

The emission properties of organic field ion emitters: A combined FIM and FI-MS investigation

The emission properties of tungsten emitters activated with benzonitrile, such as are used in analytical organic field ion mass spectrometry, have been investigated using n-heptane as test gas. It was discovered that these emission properties are influenced principally by the morphological structure and electronic state of the surfaces of the microneedles; the bulk structure of these organic agglomerates has practically no effect on their ionization behaviour.Field ion microscope investigation of emitters activated at high temperature (HT) revealed a similar surface structure to that of pyrolytic graphite; emitters activated at room temperature (RT) showed less order. The emission regions of highest electric field strength on the tips of the needles are projecting points, ledges, and in the case of HT-emitters, structure planes.A decrease in the mean emission field strength results from the formation of solid deposits on the needle surfaces. A field corrosion of the needle tips occurs in the presence of high pressures of water and leads also to an irreversible decrease in the mean emission field strength. The effect of physically adsorbed layers on the emission properties of the emitter surface is discussed in terms of the influences of the electric field penetration on the electronic properties of the needles.