电泳法制备平栅极碳纳米管场发射阴极及场发射特性研究

采用电泳法在ITO玻璃基板上选择性制备了碳纳米管(CNTs)阴极薄膜,采用电子扫描(SEM)分析了CNTs薄膜的表面形貌,并测试了碳纳米管阴极的场致发射特性.结果表明,利用电泳法制得的碳纳米管阴极薄膜均匀性、致密性良好,且具有较大发射电流密度;通过控制共面栅控CNTs场发射阴极的栅极电位能够有效控制阴极的场发射电流密度...     

应用于液晶显示器的场发射背光源制备

对应用于LCD的不同于传统管状背光源的新型面状场发射背光源(FE-BLU)的制备技术进行了研究.将表面改性碳纳米管(CNTs)丝网印刷于金属Ag精细电极上形成碳纳米管阴极,利用透射电镜与扫描电镜表征了CNTs及阴极的表面形貌.采用有机溶剂高压气流法对阴极进行表面处理,并真空封装成25.4 cm(10 in)的CNTs FE-BLU器件.测试结果表明,表面处理后阴极场发射电流密度得到明显提高,器件亮度可达5 860 cd/m2,均匀性为82%,持续发射35 h后,发射电流无明显衰减.     

应用于LCD的平栅型碳纳米管场致发射显示器背光源的研制

采用磁控溅射、光刻和湿法刻蚀技术制备平栅型场发射阴极阵列,利用电泳将碳纳米管(CNT)发射源沉积在阴极表面,将阴极板和阳极板封接后制成51cm单色平栅型CNT场致发射显示器(CNT-FED),作为背光源模板应用于49 cm液晶显示器(LCD)器件中.场发射测试表明,器件在阳极电压3 500V、栅极电压290 V时,阳极...     

带电子聚焦的氧化锌场发射背光源

液晶显示需要低功耗、均匀度好的光源作为背光源。为了降低功耗,提高显示图像质量,未来的液晶显示需要实现对背光源进行时间与阵列调制。对比现有的液晶显示用背光源,研究制备了氧化锌场发射光源。该光源采用氧化锌纳米针作为场发射阴极,采用平面栅极作为门电极调制结构实现亮度的连续可调,通过带有氧化镁二次电子发射层的金属栅网对电子进行聚焦实现光源的均匀照度。实验结果表明,带电子聚焦的氧化锌场发射光源具有较低的开启场强(1.1V/μm),较小的电压调制区间(小于150V),较高的发光强度(大于1 000cd/m2),且基于电子聚焦结构的设计,实现了光源的均匀稳定照度,可以提高液晶显示的图像质量。带电子聚焦结构的氧化锌场发射光源,既可实现对发光的时间与阵列调制,同时能提高发光的均匀性,将可作为液晶显示的理想背光源。     

电泳工艺制备阵列场发射阴极及其性能的研究

碳纳米管是理想的场发射冷阴极材料,阴极的图形阵列化是实现碳纳米管场发射显示器动态全彩视频显示的核心.三极管结构能够更好地进行矩阵寻址显示图像,且与常规的驱动电路相兼容,降低整体平板显示器件的制作成本.从实验出发,探索利用简单的电泳工艺制备图形化碳基薄膜阴极,采用与阴极成同一水平面的栅极的三极管结构,并对电泳的实验参数进行优化以提高阴极电压电流特性和发射的均匀性等问题,为场发射器件的制造提供优良的工艺基础.研究机械球磨和稀释悬浊液浓度对碳纳米管沉积均匀性的影响.实验结果表明稀薄的悬浊液的条件下可以在玻璃的银浆导电层上沉积较薄而均匀的碳纳米管膜,与丝网印刷工艺制备的阴极相比,均匀性更好,厚度更容易控制,具有更好的发射均匀性.测试图形化的阵列碳纳米阴极的三极管结构的场发射特性,发现当阳极电压保持在600 V,栅极电压接近500 V时,阳极电流能达到2.6 mA/cm2.荧光粉发光均匀,相比二极管结构具有更低的阈值电压,在亮度、均匀性和稳定性方面都有显著的优势.     

电流法改善碳纳米管阴极场发射特性

针对丝网印刷碳纳米管阴极,提出电流法进行表面后处理,有效改善碳纳米管阴极场发射特性.利用扫描电子显微镜表征电流法处理前后CNTs阴极表面形貌变化,并对处理前后CNTs阴极进行场发射特性测试.结果表明,电流法处理后CNTs阴极表面残留有机物被破坏,开启电场从2.4 V/μm降低到1.6 V/μm,同样面积的薄膜(印制面积为1 cm×1 cm)在2.6 V/μm场强下的发射电流由30 μA提高到了800 μA,说明电流处理对于提高薄膜的场发射特性有明显作用.该方法在碳纳米管场发射显示器的制作中具有很好的实际应用价值.     

CuCr合金催化剂制备条件对大电流CNTs阴极的影响

通过改变溅射功率以磁控溅射法制备了Cu/Cr合金催化剂,研究了化学气相沉积法制备的碳纳米管(CNTs)作为大电流密度场发射阴极的场发射性能。采用扫描电镜和场发射测试仪分别对不同功率催化剂制备的CNTs进行了形貌及性能分析。结果表明,根据溅射功率与催化剂颗粒的关系,可以通过调节溅射功率改变CNTs的长径比及密度,在250WCu/Cr催化剂制备的CNTs薄膜具备了良好的场发射性能,阴极电子发射的开启电场仅为1.47V/μm,当电场为3.23V/μm,发射电流密度可高达3259μA/cm2。     

脉冲激光沉积非晶碳-聚酰亚胺复合薄膜的场致电子发射研究

利用脉冲激光沉积技术制备出非晶碳-聚酰亚胺复合薄膜,并观察到其场发射阈值场强(4V/μm)比类金刚石薄膜(>12V/μm)有较大的降低,最大发射电流密度为1.2mA/cm~2.利用透明导电薄膜阳极技术可观察电子在薄膜阴极表面的发射位置.并对该复合薄膜的场电子发射机理进行了初步探讨.实验表明该复合薄膜有可能作为一种新型的场发射冷阴极材料.在平面显示器件中得到应用.     

碳纳米管场致发射平面背光源

通过酸化、球磨、超声分散等工艺制备碳纳米管(Carbon Nanotubes,CNT)悬浮液,利用电泳沉积技术制备CNT阴极,并真空封装制备成25.4cm(10in)的CNT场致发射平面背光源器件。采用扫描电子显微镜对CNT阴极样品的表面形貌进行表征,并对器件的场致发射性能进行测试。结果表明,当电场为1.76V/μm时,CNT场致发射平面背光源器件的亮度为6500cd/m2,亮度均匀性为89%,可应用于液晶显示器的背光源。     

CNTs-TiO2复合薄膜的场发射及其在电离规中的应用

介绍一种制备碳纳米管（CNTs）薄膜的方法—擦涂法。利用这种方法制备了CNTs薄膜以及CNTs-TiO2复合薄膜,对其场发射性能进行了研究,发现CNTs＋（7%～10%（质量比））TiO2复合薄膜的场发射性能与纯CNTs薄膜相比有较大改善,开启电场由2.5V/μm降低到1.3V/μm,阈值电场由4V/μm降低到3.1V/μm,场发射的均匀性与稳定性也有显著的提高。利用CNTs＋7%TiO2薄膜样品作为电离真空规的冷阴极,实现了在2×10-2～3×10-5 Pa范围内的近似线性响应,灵敏度约为3.36Pa-1。这种电离真空规具有体积小、低能耗的特点。     

场发射阵列阴极在行波管中的应用

场发射阵列阴极应用于行波管的不足主要表现在：FEAs发射不稳定、阴极发射电流密度较低及电子束存在散焦的问题．分析了产生这些问题的主要原因。提出了相应的解决方案,主要包括：提高真空度,选择合适的发射体材料,增加电阻层等,以提高电子发射的稳定性;优化发射体结构参量,改善制作方法等,以增大阴极发射的电流密度;对电子枪结构进行修改,解决电子柬散焦等问题。最后,概述了新型材料——碳纳米管在行波管中的应用现状,目前虽然还不成熟,却表现出了极大的潜力：     

钼尖场致发射阵列阴极的性能研究

利用微细加工技术和双向薄膜沉积技术对钼尖场发射阵列阴极的工艺进行了较为细致的研究，并在专用的真空系统中对所得阵列阴极的发射性能进行了测试，得到了一定的场致发射电流密度值。测试中采用数据采集系统监测栅极电压、阳极电压、阳极电流和栅极电流，测量了阴极阵列的发射稳定性和发射噪声。对发射的失效机理进行了实验研究和分析，认为发射失效的主要原因在于栅极和基底之间的漏电，尖锥和棚极孔间的暗电流，电极间的放电和放气，以及环境真空度和尖锥的均匀性等。所得结果以进一步开展有射频器件和显示器件方面的应用研究打下了一定基础。     

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。     

Field emission characteristics of nano-diamond cathode surface by graphitization pretreatment

Cathode samples of nano-diamond by graphitization pretreatment with different temperatures were fabricated by electrophoresis, then the structures and morphologies of the cathode samples were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), and the field emission tests were conducted. The effects of graphitization pretreatment on the field emission characteristics of nano-diamond cathode surface on titanium substrate are studied. The results indicate that the surface morphologies of nano-diamond cathode samples after graphitization pretreatment change a lot, and the field emission characteristics in low-voltage area are improved obviously. However, in high-voltage area, the curve distortion happens, and it doesn’t conform the mechanism of field emission characteristics.     

Effect of diamond-like carbon coating on the emissioncharacteristics of molybdenum field emitter arrays

We have studied the electron emission characteristics of Mo field emitter arrays (FEAs) using a diamond-like carbon (DLC) film deposited by a layer-by-layer technique using plasma enhanced chemical vapor deposition. The turn-on voltage was lowered from 55 to 30 V by a 20 nm thick hydrogen-free DLC coating and maximum emission current was increased from 166 to 831 μA. Also the gate voltage required to get the anode current of 0.1 (μA/emitter) decreases from 77 to 48 V. Furthermore, the emission current from DLC coated Mo FEAs is more stable than that of noncoated Mo FEAs     

A formation of cobalt silicide on silicon field emitter arrays byelectrical stress

A novel process utilizing electrical stress is proposed for the formation of Co silicide on single crystal silicon (c-Si) FEAs to improve the field emission characteristics. Co silicide FEAs formed by electrical stress (ES) exhibited a significant improvement in turn-on voltage and emission current compared with c-Si FEAs. The improvement mainly comes from the lower effective work function of Co silicide and less blunting of tips during silicidation by electrical stress in an ultra high vacuum (UHV) environment less than 10^-8 torr     

Silicide application on gated single-crystal, polycrystalline andamorphous silicon FEAs. II. Co silicide

For pt. I see ibid., vol.48, no.1, p.149-54 (Jan. 2001). For enhancement and stabilization of electron emission, Co silicides were formed from Co, Co/Ti and Ti/Co layers on silicon FEAs. Since Ti prevents oxygen adsorption on the Co film during silicidation, uniform and smooth Co silicide layers can be obtained by depositing Co first and then Ti on silicon tips, followed by rapid annealing. Among Co silicide FEAs, Co silicide formed from Ti/Co bi-layers shows the lowest leakage current, the highest failure voltage over 152 V and the largest anode current over 1 mA at the gate voltage of 150 V. Compared with silicon field emitters, the silicide FEAs formed from Ti/Co layers exhibited a significant improvement in maximum emission current, emission current fluctuation and stability, and failure voltage     

Surface morphology and I-V characteristics of single-crystal,polycrystalline, and amorphous silicon FEA's

This letter reports the surface morphology and current-voltage (I-V) characteristics of single-crystal silicon (c-Si), polycrystalline silicon (poly-Si), and amorphous silicon (a-Si) field emitter arrays (FEAs). As-deposited a-Si film has a smoother surface than poly-Si film. The surface morphology of the a-Si remains smooth even after phosphorus doping and oxidation at 950°C to be improved in emission characteristics, i.e., smaller anode current deviation among arrays smaller gate current, and higher failure voltage than those of poly-Si FEAs. Such improved characteristics can be explained by the smooth surface morphology which is kept during doping and oxidation. The surface roughness and emission characteristics of a-Si FEAs are comparable to those of c-Si FEAs     

敷ZrC的Mo Spindt阵列阴极的发射性能

对Spin＆阵列阴极表面涂敷ZrC薄膜后的发射性能进行了研究。本实验采用原位沉积的方法实现ZrC薄膜的涂敷，所谓原位沉积就是在沉积完Mo尖锥后，立刻沉积ZrC薄膜，其中，ZrC厚度为5～10nm。涂敷ZrC薄膜后的Spindt阵列阴极（ZrC FEA）在相同条件下与Mo阵列相比呈现出良好的发射性能，如相同栅极电压下的发射电流密度升高，开启电压降低。为清洁和光滑发射体表面，本实验在测试前对ZrC FEA进行了场解吸附处理，并比较了ZrC FEA在处理前后发射性能的变化。     

Carbon Nanotube-Based Triode Field Emission Lamps Using Metal Meshes With Spacers

We fabricated a carbon nanotube (CNT)-based triode field emission flat lamp with a gated emitter structure, which is composed of a metal grid with a spacer as a gate, a cathode electrode layer, and a CNT layer. The metal mesh was designed with trenches and numerous holes to make a gap between gate and cathode electrodes and to provide electrons with a highly efficient passage. We observed that this metal mesh decreased the vibration and leakage current owing to high electric field generated from anode. As a result, the uniformity and stability of this field emission lamp was improved