场发射栅孔阵列的制备

 采用硅的局部氧化技术以及湿法刻蚀技术,利用2.6 μm的光刻掩模板在n型硅片上形成了栅极孔径为1 μm的场发射阴极的栅极空腔阵列,实现了用大阵点尺寸的栅极掩模板制备较小尺寸栅孔阵列。硅的湿法刻蚀溶液采用各向同性的硝酸和氢氟酸混合溶液,刻蚀后空腔的深度和宽度均随刻蚀时间线性增加。同时,由于刻蚀溶液具有较高的Si/SiO₂ 刻蚀选择比,栅极孔径随刻蚀时间增大的速度远低于深度和宽度增大的速度,栅极孔径主要取决于掩模的尺寸和氧化层的厚度。通过选择掩模板的尺寸以及氧化层的厚度,采用局部氧化技术和湿法刻蚀技术能够制备出微米或亚微米的场发射阴极的栅极空腔阵列。     

制备高质量聚苯乙烯微球胶粒晶体的蒸发自组装法

建立了一种组装亚微米级聚苯乙烯微球的方法，称作蒸发自组装法.该方法是在一定温度下 ，聚苯乙烯微球随着分散介质的蒸发在悬浮液的气-液相界面处进行高效组装的过程.扫描电 子显微镜显示组装体为规则排列的密堆积面心立方结构.研究发现，气-液界面处生成的组装 体强烈地阻碍着分散介质的蒸发，单位时间内消耗的颗粒总数量随组装面积的增大而增加. 通过调整悬浮液的蒸发温度和组装面积，可以有效地控制悬浮液相浓度的变化，从而实现在 相浓度基本不变的情况下组装出高质量的聚苯乙烯胶粒晶体. 关键词： 蒸发自组装法 胶粒晶体 聚苯乙烯微球 三维有序大孔材料     

毛细微模塑实现单链微球的有序排列

以微米级的聚苯乙烯微球当作真实大分子链的结构单元,用软刻蚀的毛细微模塑法在玻璃基片上把它们组装成单链形状的微球串,加热使微球相互连接,从而为“亚观”尺度上模拟“大分子”链(刚性链)提供简单又直观的“模型”．并把基片上的模型链剥离下来,处于自由态．     

基于直接胶体晶体刻蚀技术的高度有序纳米硅阵列的尺寸及形貌控制

以自组装单层胶体小球阵列为掩模，采用直接胶体晶体刻蚀技术在硅表面制备二维有序尺寸可控的纳米结构.在样品制备过程中，首先通过自组装法在硅表面制备了直径200nm的单层聚苯乙烯(PS)胶体小球的二维有序阵列；然后对样品直接进行反应离子刻蚀(RIE)，以氧气为气源，利用氧等离子体对聚苯乙烯小球和对硅的选择性刻蚀作用，通过改变刻蚀时间，制备出不同尺寸的PS胶体小球的有序单层阵列；接着以此二维PS胶体单层膜为掩模，以四氟化碳为气源对样品进行刻蚀；最后去除胶体球后得到二维有序的硅柱阵列.SEM和AFM的测量结果表明：改变氧等离子体对胶体球的刻蚀时间和四氟化碳对硅的刻蚀时间，可以控制硅柱的尺寸以及形貌，而硅柱阵列的周期取决于原始胶体球的直径. 关键词： 胶体晶体刻蚀 纳米硅柱阵列     

亚微米聚苯乙烯微球在气-液界面组装的机理研究

系统地研究了亚微米聚苯乙烯微球在气-液界面的组装机理.聚苯乙烯微球在介质对流的带动下会到达悬浮液的表面并在气-液界面组装，气-液界面处聚苯乙烯微球间由弯液面产生的毛细管力是组装的推动力.界面处聚苯乙烯微球在干燥过程中其润湿性发生了转变，由完全润湿到部分润湿并最终变成不润湿，相应的聚苯乙烯微球与分散介质间接触角也逐渐增大.研究表明，只有接触角达到或超过某数值θ′_critical时，才能够出现气-液界面组装现象.考虑到PS胶粒晶体的表面是“规则”粗糙的表面，由Wenzel公式知θ′_critical大于测量值θ＝22°.聚苯乙烯微球润湿性的转变是界面组装发生和持续进行的关键性因素. 关键词： 自组装 胶粒晶体 聚苯乙烯微球 润湿性     

亚微米聚苯乙烯微球在气-液界面组装的机理研究

系统地研究了亚微米聚苯乙烯微球在气-液界面的组装机理.聚苯乙烯微球在介质对流的带动下会到达悬浮液的表面并在气-液界面组装，气-液界面处聚苯乙烯微球间由弯液面产生的毛细管力是组装的推动力.界面处聚苯乙烯微球在干燥过程中其润湿性发生了转变，由完全润湿到部分润湿并最终变成不润湿，相应的聚苯乙烯微球与分散介质间接触角也逐渐增大.研究表明，只有接触角达到或超过某数值θ′_critical时，才能够出现气-液界面组装现象.考虑到PS胶粒晶体的表面是“规则”粗糙的表面，由Wenzel公式知θ′_critical大于测量值θ＝22°.聚苯乙烯微球润湿性的转变是界面组装发生和持续进行的关键性因素. 关键词： 自组装 胶粒晶体 聚苯乙烯微球 润湿性     

亚微米尺寸元件的离子束刻蚀制作

采用软光刻技术中的微接触印刷(μCP)技术、表面诱导的水蒸气冷凝、表面诱导的去湿行为,在金基底上制作出了亚微米的环状周期结构聚合物掩膜.通过对离子束刻蚀过程中各个参量对刻蚀元件的表面光洁度、轮廓保真度和线宽分辨的影响分析,结合掩膜的实际情况选择出了合适的离子束入射角、离子能量、束流密度和刻蚀时间等参量.依照这些参量刻蚀出了高质量的亚微米尺寸环状周期结构元件.通过对刻蚀出的元件的检测发现,刻出的元件表面光洁度、轮廓保真度和侧壁陡峭度都非常好.     

氧化钨二维微米球腔阵列对聚苯胺电致变色的影响

采用气/液界面自组装方法制备规整排列的聚苯乙烯微球二维单层结构,以此为模板,采用电化学沉积法在电极表面构筑了有序的氧化钨微球腔阵列,进一步在氧化钨球腔内电化学沉积聚苯胺,采用吸收光谱研究了电极表面球腔阵列结构对聚苯胺电致变色行为的影响.     

金刚石锥阵列的无掩膜刻蚀制备及其形貌演变机制

为获得具有优良场发射性能的金刚石锥阵列,利用偏压热灯丝化学气相沉积系统分别在高质量大颗粒金刚石厚膜与纳米金刚石薄膜上进行了无掩膜刻蚀研究,系统比较了高质量大颗粒金刚石厚膜与纳米金刚石薄膜的刻蚀特性,制备了大面积均匀金刚石锥阵列和高长径比(20∶1)金刚石纳米线阵列,探讨了金刚石锥的刻蚀形成机理。     

铬过渡层对纳米球刻蚀法制备二维银纳米结构的影响

研究了铬过渡层对纳米球刻蚀法制备二维银纳米点阵结构的影响。首先利用自组装的方法在玻璃基底上制备出单层排列的聚苯乙烯纳米球阵列,然后使用物理气相沉积的方法在二维聚苯乙烯纳米球阵列上沉积一层铬层作过渡层和银层,最后将玻璃基底在乙醇溶液中超声移除聚苯乙烯纳米球,得到二维的银纳米点阵。实验发现,随着铬过渡层厚度的增加,制得的二维银纳米点阵阵列趋于完整,单个的银纳米颗粒由椭圆状转变为三角形形状。实验中测量了所得到的二维银纳米结构的吸收光谱。     

Field emission performances of CNTs bundles array

The field emission performances of normal-gate cold cathode, which is composed of different multi-wall carbon nanotubes (MWCNTs) bundles array are calculated. The device parameters such as the arrangement of bundles, array density, gate location, gate voltage, anode voltages and anode–cathode distance affect the field emission properties, which is discussed in detail. The results reveal that the hexagon bundles array needs a lower threshold voltage than square array to reach high field enhancement factor and large emission current density. The emission current density is two orders larger than that of the oxide emitter. The optimal bundles array densities of hexagon and square array to get field enhancement factor are 0.0063 and 0.00375 μm⁻², respectively. Meanwhile, the field emission performances are impacted critically by gate location and gate voltage. Field emission properties changed little while the anode–cathode distance varies within tens of micrometers, which increases the process-friendliness of CNTs field emission devices.     

Micro-gated-field emission arrays with single carbon nanotubes grown on Mo tips

Using our approach previously reported, we have fabricated relatively large area micro-gated-field emission arrays with carbon nanotube (CNT) grown on Mo tips. By redesigning the device and fabrication processes, the percentage of single CNTs increased to about 50-70% with a substantial improvement in leakage current between gate and cathode and gate interceptive current. The I-V measurement of a 11000 cell array at a gate to cathode voltage of 92 V showed an anode current of 1.2 mA, corresponding to a current density of 0.57 A/cm², with a gate current only 3.3% of the anode current.     

Growth of GaAs/AlGaAs hexagonal pillars on GaAs (1 1 1)B surfaces by selective-area MOVPE

We report on the growth of GaAs and GaAs/AlGaAs heterostructured hexagonal pillar structures using selective area (SA) metalorganic vapor phase epitaxy (MOVPE). By performing growth on SiO₂-masked (1 1 1)B GaAs substrates with circular or hexagonal hole openings, extremely uniform array of hexagonal GaAs/AlGaAs pillars consisting {1 1 0} vertical facets with their diameter of order of 100 nm were obtained. Unexpectedly, strong intense light emission was observed for the room temperature photoluminescence measurement of the pillar arrays in triangular lattice, which is promising for the application to the photonic crystals to enhance the light extraction efficiency from the materials with high refractive index. Furthermore, it was also found that hexagonal pillars with size 60 nm and large aspect ratio (>100) by reducing the size of initial hole size of mask, opening a possibility to grow nanowires using epitaxial growth.     

Fabrication and field emission properties of multi-walled carbon nanotube/silicon nanowire array

Silicon nanowire (SiNW) arrays were fabricated on silicon wafers by the metal-assisted chemical etching method. Varied average diameters of SiNW arrays were realized through further treatment in a mixed agent of HF and HNO₃ of certain concentrations. After the treatment, there were more than 93% SiNWs with diameters smaller than 100 nm. The tip of each SiNW was subsequently wrapped with multi-walled carbon nanotubes (MWCNTs) with chemical vapor deposition method. The as-fabricated MWCNT/SiNW arrays were fabricated into electric field emitters, with turn-on field of 2.0 V/μm (current density: 10 μA/cm²), much lower than that of SiNW array (5.0 V/μm). The turn-on electric field of MWCNT/SiNW array decreased with the decreasing of the average diameter of SiNWs, indicating the performance of the field emission is relative to the morphology of SiNWs. As the SiNW array is uniform in height and easy to fabricate, the MWCNT/SiNW array shows potential applications in flat electric display.     

Fabrication of large-scale periodic silicon nanopillar arrays for 2D nanomold using modified nanosphere lithography

We present a fabrication procedure that can form large-scale periodic silicon nanopillar arrays for 2D nanomold which determines the feature size of nanoimprint lithography, using modified nanosphere lithography. The size of silicon nanopillars can be easily controlled by an etching and oxidation process. The period and density of nanopillar arrays are determined by the initial diameter of polystyrene (PS) spheres. In our experiment, the smallest nanopillar has a full width half maximum (FWHM) of approximately 50 nm, and the density of silicon pillar is ∼10⁹/cm². Using this approach, it is possible to fabricate 2D nanoimprint lithography mask with 50 nm resolution.     

Field emission of carbon nanotube array with normal-gate cold cathode

A hexagon pitch carbon nanotube (CNT) array vertical to the normal gate of cold cathode field emission displayer (FED) is simulated by solving the Laplace equation. The calculated results show that the normal gate causes the electric field around the CNT tops to be concentrated and emission electron beam become a column. The field enhancement factor and the emission current intensity step up greatly compared with those of diode structure. Emission current density increases rapidly with the decrease of normal-gate aperture. The gate voltage exerts a critical influence on the emission current.     

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.     

The surface plasmon resonance of metal-film nanohole arrays

In this paper we investigated the enhanced transmission and surface plasmon resonance through a thin gold film with a periodic array of subwavelength nanoholes. Both freestanding gold-film nanohole arrays and gold-film nanohole arrays deposited on a gallium arsenide (GaAs) substrate are considered. Periodic arrays of nanoholes exhibit two different surface plasmon resonance features: localized waveguide resonance and the well-recognized photonic crystal resonance. The tangential electric field component $Ey$ is nonzero only in the hole region for a freestanding gold-film nanohole array, but it can exist in the hole region and in the metallic region for a gold-film nanohole array deposited on a GaAs substrate.     

Electrodeposition of aligned ZnO sheet array on ITO substrate and their field emission characteristics

ZnO sheet array was fabricated by a simple electrodeposition method on the transparent ITO substrate at a temperature of about 60℃. The field emission properties of the ZnO sheet array were investigated. The fluctuation of the field emission current is less than 5% over several hours. The Fowler Nordheim curves with a roughly linear characteristic were obtained by analysing the current density and the intensity of the electrical field. The results prove that such a simple electrochemical method can potentially meet the demands on the production of cold cathodes for field emission display.[第一段]     

Carbon nanodot arrays grown as replicas of specially widened anodic aluminum oxide pore arrays

Via a specially widened anodic aluminum oxide (AAO) pore arrays, carbon nanodot arrays with uniform size and high density were obtained through filtered cathodic arc plasma (FCAP) technique. The AAO template was prepared in oxalic acid by multi-steps to get a specially enlarged opening which plays an important role in the deposition of nanodots. The morphology of the nanodots was studied by a field emission scanning electron microscopy (FESEM). The diameter of the as-prepared nanodot demonstrated here is about 100 nm at the bottom and less than 40 nm at the top, and the density was estimated to 10¹⁰ cm⁻². Field emission properties of the nanodot arrays were investigated and a low threshold field of 5.1 V/μm at 10 mA/cm² was obtained. In this paper, the carbon nanodot arrays grown as replicas of the specially widened AAO template may support a strategy to realize the fabrication of nanodot arrays with various materials.