Improvement in the intense pulsed emission stability of grown CNT films via an electroless plated Ni layer

Carbon nanotube(CNT)films were grown on silicon wafers with and without a nickel layer(Si-CNT and Ni-CNT)via the pyrolysis of iron phthalocyanine.The nickel layer was prepared using the electroless plating method.To study the emission stability of Si-CNT and Ni-CNT cathodes during intense pulsed emission,emission characteristics were measured repeatedly with a diode structure using a Marx generator as a voltage source.For the peak values of the pulsed voltage,which were in the range between 1.62-1.66 MV(corresponding to electric field intensities between 11.57-11.85 V/μm),the first cycle emission current was 109.4 A for Si-CNT and 180.5 A for Ni-CNT.By comparing the normalized emission currents of the Si-CNT and Ni-CNT cathodes,the improvement in the emission stability can be easily quantified.The number of emission cycles necessary for the peak current to decay from 100%to 50%increased from~3 for Si-CNT to~11 for a Ni-CNT film.     

氧化锌/银双层膜负反馈阴极电极的制备及性能研究

提出了一种可显著改善碳纳米管(CNTs)场致发射性能的ZnO/Ag双层膜负反馈阴极电极的制备方法.在条形银电极上溅射沉积一定厚度的Zn膜,经热氧化和湿法刻蚀制备成ZnO/Ag双层膜电极.同单层的Ag或氧化铟锡电极相比,该电极不仅具有足够的负反馈电阻(限流电阻)阻止CNTs场发射中过流的发生,而且降低了条形阴极电极的线性电阻,确保了场发射的均匀性.当溅射沉积Zn膜的厚度从40 nm增到120 nm时,热氧化形成的ZnO由孤岛状的颗粒变为连续体的薄膜,ZnO/Ag双层膜电极的表面光洁度比单层的Ag电极有很大的提高,负反馈电阻层的电阻增大,负反馈的能力增强.CNTs薄膜阴极场发射特性曲线证明,ZnO/Ag双层膜电极能明显降低场发射电流的波动,有效提高器件的稳定性和寿命.     

氮化硼薄膜的厚度对场发射特性的影响

利用射频磁控溅射方法, 在n型（100）Si基底上沉积了不同厚度（54~124 nm）的纳米氮化硼（BN）薄膜. 红外光谱分析表明, BN薄膜结构为六角BN（h-BN）相(1 380 cm^-1和780 cm^-1)结构. 在超高真空系统中测量了不 同膜厚的场发射特性, 发现阈值电压随着厚度的增加而增大. 厚度为54 nm的BN薄膜样品阈 值电场为10 V/μm, 当外加电场为23 V/μm时, 最高发射电流为240 μA/cm². BN薄膜场发射F-N曲线表明, 在外加电场作用下, 电子隧穿了BN薄膜表面势垒发射到真空.     

基底偏压对氮化硼薄膜场发射特性的影响

利用射频磁控溅射方法, 在n型（100）Si（0.008～0.02 Ω·m）基底上沉积了氮化 硼（BN）薄膜. 红外光谱分析表明, BN薄膜结构均为六角BN（h-BN）相. 在超高真空系统中 测量了BN薄膜的场发射特性, 发现BN薄膜的场发射特性与基底偏压关系很大, 阈值电场随基 底偏压的增加先增加后减小. 基底偏压为-140 V时BN薄膜样品场发射特性要好于其他样品, 阈值电场低于8 V/μm. F~N曲线表明, 在外加电场的作用下, 电子隧穿BN薄膜表面势垒发射 到真空.     

基底温度对氮化硼薄膜场发射特性的影响

利用射频磁控溅射方法, 真空室中充入高纯N_{2(99.99%)和高纯Ar（99.99%）的混合气体, 在n型（100）Si基底上沉积了六角氮化硼（h-BN）薄膜. 在超高真空（<10^-7 Pa）系统中测量了BN薄膜的场发射特性, 发现 沉积时基底温度对BN薄膜的场发射特性有很大影响. 基底温度为500 ℃时沉积的BN薄膜样品场发射特性要好于其他薄膜, 阈值电场为12 V/μm, 电场升到34 V/μm, 场发射电流为280 μA/cm². 所有样品的Fowler-Nordheim(F-N)曲线均近似为直线, 表明电子是通过 隧道效应穿透BN薄膜发射到真空的.}     

碳纳米管/纤维阴极场发射平板显示器研制

探索了从碳纳米管/纳米纤维（CNT/CNF）的制备到CNT/CNF阴极场发射平面显示器(c-FED)封装的工艺流程.用化学气相沉积方法,优化制备条件获得了纯度较高的CNT/CNF;以 CNT/CNF和低压荧光粉为原料,采用丝网印刷工艺制作显示器的阴极和阳极;采用类真空荧光显示器的封装工艺封装了c-FED样管.所研制的c-FED具有优良的场发射性能,较好的均匀性及发光密度,黄色荧光粉的c-FED在电场为 2.7 V/μm时的亮度可达600 cd/m².因该显示器使用普通玻璃作为阴阳极基板,整个工艺流程在大面积和实用化方面有很好的应用潜力.      

碳化硅薄膜制备及其场发射特性

采用热丝化学气相沉积法在Si（111）、Ti（101）衬底上制备了SiC薄膜,并利用X射线衍射和傅里叶变换红外吸收光谱（FTIR）对薄膜的结构、成分及化学键合状态进行了分析．XRD结果表明,制备的SiC薄膜呈现3C-SiC结晶相,有很好的择优取向性．HIR谱显示,薄膜的吸收特性主要为Si-C键的吸收,其吸收峰为804．95cm^-1．从原子力显微镜对SiC薄膜表面形貌的测试分析可以看出,样品表面呈规则精细颗粒状结构且薄膜结构致密．此外,在高真空系统中（6．0×10^-4Pa）对生长的SiC薄膜进行场敛发射特性测试,结果表明生长的SiC薄膜具有场致发射特性：样品的开启电压为82．1V／μm,最大电流密度为631．5μA／cm^2．     

Field Emission of SiCN Thin Films Bombarded by Ar~+ Ions

0　IntroductionInthefieldofvacuummicroelectronicdevices,coldcathodeelectronfieldemittersarepotentiallyusefulforfieldemissiondisplays (FED) .FEDareimportantelementsoftheflatpaneldisplays.Comparingwithliquidcrystaldisplays (LCD)andcath oderaytube (CRT)displays,ithasacompactsize ,alargeview ingangle ,excellentbrightnessandhighpicturequality[1 ] .Muchresearchhasbeenperformedtounderstandandimprovethefieldemissionpropertiesofthinfilmsandthinfilmstructures.Withthedevelopmentsofvacuummicroelectro…     

Field emission of SiCN thin films bombarded by Ar<Superscript>+</Superscript> ions

SiCN thin films were synthesized by a radio frequency chemical vapor deposition (RFCVD) system on P-type Si (1 0 0) wafers using C₂H₄, SiH₄ and N₂ as raw materials, In order to get rid of the oxygen absorbed on the surface and improve the characteristics of electron field emission, Ar⁺ ions of low energy were used to bombard the samples. The field emission characteristics of SiCN thin films before and after Ar⁺ bombardment were studied in the super vacuum environment of 10⁻⁶ Pa. It was showed that the turn-on field (defined as the point where the current-voltage curve shows a sharp increase in the current density) decreased from 38 V/μm before bombardment to 25 V/μm after bombardment. And the maximum emission current density increased from 159.2 to 267.4 μA/cm². The composition before and after Ar⁺ bombardment was compared using X-ray photoelectron spectroscopy (XPS). Our results illustrated that the field emission characteristics were improved after the bombardment of Ar⁺. Foundation item: Supported by the National Natural Science Foundation of China (19975035) Biography: Ma You-peng (1978), male, Master candidate, research direction: novel functional materials film and ion beam modification of materials.     

Electron field emission from nano-crystalline Si films deposited by inductively coupled plasma CVD at room temperature

ELECTRON FIELD EMISSION IS ONE OF THE INTERESTING PER- FORMANCES OF NANO-SCALE MATERIALS [1-3]. CARBON NANO- TUBES HAVE BEEN DEMONSTRATED TO BE THE MOST FASCINAT- ING MATERIAL OF ELECTRON FIELD EMISSION, BUT THEIR INSTA- BILITY OF EMISSION DUE TO THE AGING EFFECT LIMITS THEIR APPLICATION IN VACUUM ELECTRONICS [4]. SI TIPS HAVE MORE FAVORITE GEOMETRIC FEATURE AND MORE STABLE C…     

Simple method to rapidly fabricate chain-like carbon nanotube films and its field emission properties

A simple process to fabricate chain-like carbon nanotube (CNT) films by microwave plasma-enhanced chemical vapor deposition (MPCVD) was developed successfully. Prior to deposition, the Ti/Al₂O₃ substrates were ground with Fe-doped SiO₂ powder. The nano-structure of the deposited films was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The field electron emission characteristics of the chain-like carbon nanotube films were measured under the vacuum of 10-5 Pa. The low turn-on field of 0.80 V/μm and the emission current density of 8.5 mA/cm2 at the electric field of 3.0 V/μm are obtained. Based on the above results, chain-like carbon nanotube films probably have important applications in cold cathode materials and electrode materials.     

Silicon Field Emission Arrays Coated with CN_x Thin Films

0　IntroductionThefieldemissiondisplay (FED) ,whichhasthebenefitsofbothliquidcrystaldisplays (LCDs)andcathoderaytube(CRT)display ,isregardedasaperfectchoiceforthefuturedis plays.Ithasacompactsize,alargeviewingangle,excellentbrightnessandhighpicturequality[1 ] .Thefieldemissionarrays(FEAs) ,whichareformedofarraysofmicro tips,arewidelyusedasthesourceofelectroninFED .Thetopofthetipiswherethestrongestelectricfieldis.Itisalsowheremostoftheemissionelectronscomefrom .Thismadeitpossibleto putel…     

Enhanced Field Emission from Printed Carbon Nanotubes by Hard Hairbrush

A method, the morphology of screen printed carbon nanotube pastes is modified using a hard hairbrush, is presented. In this way, the organic matrix material is preferentially removed. Compared to those untreated films, the turn-on electric field of the treated film decreases from 2.2V/μm to 1.6V/μm, while the total emission current of the treated increases from 0.6mA/cm2 to 3mA/cm2, and uniform emission site density image has also been observed.     

Analytical optimization for field emission of carbon nanotube array

To optimize field emission （FE） property of carbon nanotube （CNT） array on a planar cathode surface, the Fowler-Nordheim formula has been used to discuss the maximum of the emission current density with the floating sphere model in this paper. The emission current density is dominating as the analytical Fowler-Nordheim function of the intertube distance, and the maximum of the emission current density is deduced and discussed. The results indicate that the intertube distance in CNT array critically affects the field enhancement factor and the emission current density, whose maximum occurs at the intertube distance approximating a tenth of the tube height. Considering the emission current density and the field enhancement factor, the FE can be optimized analytically when the intertube distance is about a tenth of the tube height.     

非定向氧化锌纳米线阵列的场发射

使用热蒸发的方法在硅基底上制备了非定向氧化锌（ZnO）单晶纳米线阵列。经过热蒸发之后,在硅基底上形成一层均匀分布的 ZnO 点。在这些 ZnO 点上生长出非定向的 ZnO 纳米线阵列,其中的纳米线直径大约在 10 到 20nm 之间。考虑到实用,在制备样品的过程中硅基底的温度始终保持在 500℃ 以下。然后测量了这些非定向 ZnO 纳米线阵列的场发射特性。在 5.5V·μm^-1 场强下得到了 10μA·cm^-2 的场发射电流密度;同时使用透明阳极技术观察了其场发射中心的分布。     

胶体石墨涂层的平面场发射特性研究

研究了胶体石墨涂层的场发射特性。测得其相应于10μA/cm²场发射电流密度的开启场强为5.4V/μm,相应于1mA/cm²场发射电流密度的阈值场强为8.8V/μm。扫描电子显微镜观察表明场发射应该来自细小石墨碎片的尖锐边缘。通过计算估计出这些尖锐边缘处的场强比阴阳极之间的平均场强增加了大约4×10²倍。     

两步法制备性能优良的ZnO纳米线

利用热蒸发和溶液浸泡两步法制备了性能优良的ZnO纳米线,研究了这些ZnO纳米线的光致发光和场发射特性.与直接采用热蒸发方法生长的ZnO纳米线相比,由该方法得到的ZnO纳米线表现出了更好的紫外发光特性,同时发生5 nm的蓝移,场发射测试表明其开启电场和阈值电场分别达到2.3 V/μm和6.8 V/μm.该方法适用于制备光致发光和场发射性能优良的ZnO纳米线.     

Silicon field emission arrays coated with CN<Subscript>x</Subscript> thin films

Arrays of silicon micro-tips were made by etching the p-type (1 0 0) silicon wafers which had SiO₂ masks with alkaline solution. The density of the micro-tips is 2×10⁴ cm⁻². The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly. The CN_x thin film, with the thickness of 1.27 μm was deposited on the silicon micro-tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X-ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5%, N: 12.6% and O: 17.9%. The silicon arrays coated with CN_x thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm² at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CN_x thin films are likely to be good field emission cathode. The preparation and the characterization of the samples were discussed in detail. Foundation item: Supported by the National Natural Science Foundation of China (19975035) Biography: Chen Ming an (1978-), male, Ph. D candidate, research direction: novel functional materials film and ion beam modification of materials.     

金刚石薄膜的制备、表征和场发射性能

系统研究了在微波等离子体化学气相沉积(MPCVD)系统中,甲烷浓度、沉积气压、气体流量比、衬底的预处理等参数工艺对金刚石薄膜质量的影响,不同样品的扫描电镜(SEM)图片表明上述参数工艺对金刚石薄膜的微观形貌如:晶粒尺寸、均匀性、膜的连续性、致密性等具有重要影响.金刚石薄膜样品尖锐的1332cm-1Raman峰表明金刚石膜具有很高的晶化质量,与SEM图片一致.最后研究了样品的场发射特性,获得了较低的发射阈值电压4.4V/μm,电压为650V时,得到较高的约128mA/cm2的发射电流密度.     

掺氮碳纳米管阵列的制备及其场发射特性

使用结构简单的单温炉设备,以二茂铁为碳源与催化剂,三聚氰胺为氮源在硅基底制备出了碳纳米管阵列。所得的碳纳米管为多壁结构,单根碳纳米管的平均直径为50nm,长度为15μm,有着很好的定向性。透射电子显微镜(TEM)和X射线光电子谱(XPS)分析表明所得的碳纳米管是氮掺杂的。利用场发射显微镜研究了掺氮碳纳米管阵列的平面场发射特性,相应的开启场强为1.60V/μm,场发射图像表明了其有较高的场发射点密度。