硝酸盐对电泳沉积钛基石墨烯冷阴极场发射性能的影响

采用电泳沉积的方法在金属钛片衬底上制备石墨烯冷阴极。研究了Mg(NO3)2·6H2O、Zn(NO3)2·6H2O和Al(NO3)3·9H2O对石墨烯冷阴极表面形貌、成分以及场发射性能的影响。用原子力显微镜(AFM)对自制氧化石墨烯的尺寸和厚度进行了表征,用扫描电镜(SEM)和傅里叶变换红外光谱(FT-IR)分析了石墨烯冷阴极表面的结构和组成。场发射测试结果表明:不同的硝酸盐对电泳制备的石墨烯冷阴极的场发射性能产生了影响。采用Mg(NO3)2·6H2O时,所得的石墨烯冷阴极场发射性能最好,开启场为3.3 V/μm,阈值场为6.3 V/μm。     

类金刚石膜的结构与性能研究

用激光Ｒａｍａｎ谱和ＸＲＤ谱对用直流－射频等离子体化学气相沉积法制备的类金刚石膜的结构进行了分析，并研究了工艺参数对膜的沉积速率，内应力和直流电阻率的影响，结果表明，类金刚石膜是由ｓｐ＾２和ｓｐ＾３键组成的非晶态碳膜，当负偏压高于３００Ｖ时，膜中ｓｐ＾３／ｓｐ＾２键的比值随负偏压的升高而降低，类金刚膜的沉积速率与负偏压Ｖｂ的成正比，膜内存在１～４．７ＧＰａ的压应力，随负偏压的升高而降低，膜的电阻率     

金刚石膜技术及应用

金刚石膜突破了人造金刚石在尺寸上的限制,使金刚石的优异性能得到了充分的发挥,从而大幅度拓展了金刚石的应用领域。文章叙述了金刚石膜及其发展历程,综述了其日益繁多的制造技术以及在现代技术中越来越广阔的应用,对我国金刚石膜技术应用中存在的问题及其发展前景提出了一些看法。     

液相沉积类金刚石膜的沉积机理研究

根据电化学的相关理论,提出了钛合金表面液相沉积DLC膜的反应机理,给出了可能电极过程,认为膜是通过甲基阳离子的亲电取代反应而不断生长。讨论了氢原子对金刚石结构的稳定作用,并解释了实验条件对膜结构和性能的影响。     

纳米金刚石薄膜的制备及场发射研究进展

纳米金刚石薄膜因具有纳米材料和金刚石的双重性质且易于制备,作为场发射材料在平板显示领域拥有潜在的应用价值,而引起人们的极大兴趣。本文对近年来国内外有关纳米金刚石薄膜的制备、场发射的研究现状进行了综述。     

微米/纳米金刚石膜的性能和应用

从现今已知的材料而言,金刚石集力学、电学、热学、声学、光学以及化学惰性等如此多的优异性于一身,这正是科技工作者所期望的,而且也正是其吸引如此众多的跨学科的科技工作者投入研究的缘故.金刚石膜是21世纪有发展前途的新型材料,日本、美国和欧洲工业界正在大力开发金刚石膜的应用.通过广大科技工作者的深入研究,大胆实践,无论是生长理论、方法和应用都取得了重大突破,使得其在现代科学技术和现代工业的高速发展中发挥重要作用.     

单晶金刚石膜与多晶金刚石膜的制备工艺及性能

本文主要介绍了用微波等离子体化学气相沉积法(以下简称MP CVD法)以甲醇-氢气混合气和丙酮-氢气混合气为源气体,分别以单晶硅的(111)面和人造金刚石的(100)面为衬底材料,制备出了面积为20mm×20mm厚为10μm的多晶金刚石膜和面积为1.0mm×1.0mm厚为5μm的单晶金刚石膜。通过试验发现,源气体配比和衬底温度对薄膜质量起决定性作用。另外,衬底在反应腔中的位置对薄膜的生成也有很大影响。单晶金刚石膜制备过程中衬底金刚石的晶体取向与金刚石薄膜的生长及质量有密切的关系。在金刚石的(100),(110)和(111)面上分别获得了单晶金刚石膜和金刚石多晶粒子。选用扫描电镜、显微激光拉曼、反射电子衍射对多晶金刚石膜及单晶金刚石膜的性能进行了测试。     

类金刚石膜的制备及应用

类金刚石膜(DLC)由于其良好的特性被广泛应用于各个领域,文章介绍了类金刚石膜的制备方法及特点,并说明了利用类金刚石膜耐磨损高硬度等特点,将类金刚石薄膜经过特殊的方法形成类金刚石纤维的过程,探讨了其在纤维砂轮中,代替Al2O3纤维作为磨料的应用.     

金刚石与人类社会(下)

详细介绍了天然金刚石的发现、特性、鉴别方法和应用范围,论述了金刚石粉体、单晶金刚石、金刚石膜和聚晶金刚石的人工合成方法和应用情况.     

金刚石与人类社会(上)

详细介绍了天然金刚石的发现、特性、鉴别方法和应用范围,论述了金刚石粉体、单晶金刚石、金刚石膜和聚晶金刚石的人工合成方法和应用情况.     

Diamond vacuum field emission devices

This article reports the development of (a) vertical and (b) lateral diamond vacuum field emission devices with excellent field emission characteristics. These diamond field emission devices, diode and triode, were fabricated using a self-aligning gate formation technique from silicon-on-insulator wafers using conventional silicon micropatterning and etching techniques. High emission current >0.1 A was achieved from the vertical diamond field emission diode with an indented anode design. The gated diamond triode in vertical configuration displayed excellent transistor characteristics with high DC gain of 800 and large AC output voltage of 100 V p–p. Lateral diamond field emission diodes with cathode–anode spacing less than 2 μm were fabricated. The lateral diamond emitter exhibited a low turn-on voltage of 5 V and a high emission current of 6 μA. The low turn-on voltage (field 3 V/μm) and high emission characteristics are the best of reported lateral field emitter structures.     

Long-term stability of a horizontally-aligned carbon nanotube field emission cathode coated with a metallic glass thin film

A horizontally-aligned carbon nanotube (HACNT) field emission cathode was coated with a metallic glass thin film (MGTF) to improve the stability of the field emission properties. HACNT field emission cathodes have previously been fabricated on glass substrates using composite plating and crack-formation techniques. A carbon nanotubes/nickel (CNTs/Ni) composite film is deposited onto a glass substrate at 80 °C by the composite plating technique alone. Cracks are then formed in the CNT/Ni composite film during 30 min heating at 300 °C, and HACNTs are exposed in the cracks. The field emission properties of the HACNT field emission cathode show a low turn-on electric field E_on of about 2.3 V/μm, a low threshold electric field E_th of about 4.7 V/μm at an emission current density of 1 mA/cm², and a stability time of 78 h. The degradation of the HACNT field emission cathode is prevented by using a MGTF-coating technique and superior long-term stability (i.e. >125 h, with 5 nm MGTF; >270 h, with 10 nm MGTF) for the MGTF/HACNT field emission cathode is achieved.     

Shadow mask field emission display with carbon nanotubes emitters

Printable carbon nanotubes field emission displays with shadow mask (Shadow Mask CNT-FED) is suggested. A layer of insulator is screen printed on the upper surface of shadow mask, and address electrodes are fabricated on it. MgO film is deposited on shadow mask by electron beam evaporation. Secondary emission electrons escape from MgO film under the bombardment of primary electrons. In the simulation, 93% of the landing electrons are found to be secondary emission electrons. The modulating amplitude of the voltage on the address electrodes is low (∼ 250 V) because of the low-energy secondary emission electrons. The comparable results are also got from the experiments. The modulating amplitude of the voltage is found to increase with the thickness of the insulator. The optimized thickness (40 ∼ 50 μm) and the fabrication process of the insulator are suggested in this research report.     

Application of diamond film to cold cathode fluorescent lamps for LCD backlighting

A cold cathode fluorescent lamp (CCFL) is a gas discharge light source widely used for liquid crystal display (LCD) backlighting. We proposed applying diamond as a new cathode material to reduce the power consumption of the CCFL. In this work, we show stable and low (less than 50% of metal) cathode-fall voltage for a glass discharge tube.     

An under-gate triode structure field emission display with carbon nanotube emitters

A new triode structure for field emission displays based on carbon nanotube emitters is demonstrated. In this structure, gate electrodes are located underneath the cathode electrodes with an in-between insulating layer, a so-called under-gate type triode structure. Although the gate is on the opposite side of the anode with respect to the cathode electrodes, modulation of electron emission from the carbon nanotube emitters by the gate voltage is confirmed. The simple structure and fabrication process may lead to practical applications for the under-gate triode type structure.     

Superior integrated field emission cathode with ultralow turn-on field and high stability based on SiC nanocone arrays

Low turn-on field (E_to) and stable electron emission are two of key parameters for reliable application of field emission (FE) cathodes. In the present work, we developed a novel high-performance integrated field emission cathode based on well-aligned SiC nanocone arrays via an electrochemical etching approach. The etched SiC nanocone emitters and the underlying remaining SiC wafer are designed into a single-crystalline integrated architecture without interfaces, which favors cathodes with a sturdy configuration to resist Joule heat during long period electron emission process and structural failure caused by the existed strong electrostatic forces. Accordingly, the E_to of the integrated SiC cathode is reduced to 0.32 V/μm, which is the lowest value among all the previously reported SiC nanostructured emitters. In addition, the integrated cathode presented superior stability with an electron emission fluctuation of 3.3% over 10 h. This work provides a new perspective for designing and fabricating advanced FE cathodes for further promising applications in harsh working conditions with high performance.     

Secondary electron emission in a triode carbon nanotube field emission display and its influence on the image quality

The secondary electron (SE) emission (SEE) in a triode carbon nanotube (CNT) field emission display (FED) and its influence on the image quality have been studied with a 3.5 in. vacuum-sealed FED prototype fabricated by using screen printing and frit sealing techniques. By analyzing the emission property difference of the device under two different kinds of work modes, we have found that it is the SEE from the insulator above the gate that induced the anode image distortion of FED under normal work mode. Two improved structures, by decreasing the size of insulator layer and by coating a conductive layer to stabilize the potential of the insulators, are provided to eliminate SEE influence and achieved a uniform anode image. It is expected that our results will benefit the research and design of CNT FED with high performance.     

Enhanced field electron emission properties of hierarchically structured MWCNT-based cold cathodes

Hierarchically structured MWCNT (h-MWCNT)-based cold cathodes were successfully achieved by means of a relatively simple and highly effective approach consisting of the appropriate combination of KOH-based pyramidal texturing of Si (100) substrates and PECVD growth of vertically aligned MWCNTs. By controlling the aspect ratio (AR) of the Si pyramids, we were able to tune the field electron emission (FEE) properties of the h-MWCNT cathodes. Indeed, when the AR is increased from 0 (flat Si) to 0.6, not only the emitted current density was found to increase exponentially, but more importantly its associated threshold field (TF) was reduced from 3.52 V/μm to reach a value as low as 1.95 V/μm. The analysis of the J-E emission curves in the light of the conventional Fowler-Nordheim model revealed the existence of two distinct low-field (LF) and high-field (HF) FEE regimes. In both regimes, the hierarchical structuring was found to increase significantly the associated β_LF and β_HF field enhancement factors of the h-MWCNT cathodes (by a factor of 1.7 and 2.2, respectively). Pyramidal texturing of the cathodes is believed to favor vacuum space charge effects, which could be invoked to account for the significant enhancement of the FEE, particularly in the HF regime where a β_HF as high as 6,980 was obtained for the highest AR value of 0.6.