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     

纳米球刻蚀法制备的二维有序的CdS纳米阵列及其光学性质的研究

采用纳米球刻蚀(nanosphere lithography)技术,以自组装的聚苯乙烯纳米小球(polystyrene,PS小球)的单层膜为掩模,制备出二维有序的CdS纳米阵列.利用扫描电子显微镜(SEM)对样品结构进行了表征,用紫外—可见分光光度计对样品光学性质进行了分析.结果表明：制备的二维CdS纳米阵列是高度有序的,且与作为掩模的纳米小球的原始尺寸及排布结构一致;禁带宽度为2.60eV,相对于体材料的2.42eV,向短波长蓝移了0.18eV,表现出CdS材料在纳米结构点阵中的量子尺寸效应;CdS纳米 关键词： 纳米球刻蚀 二维CdS纳米有序阵列     

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。     

一种用于LSPR传感器的准正方型银纳米颗粒阵列制备

首先控制聚苯乙烯纳米球(PS球)乳液在基片上的干燥温度,采用自组装方法,使用单一粒径的PS球制备出单层的PS球亚稳态正方排列结构模板。然后,在模板上通过磁控溅射法沉积一层银膜。利用纳米球光刻技术,去掉PS球模板得到二维正方点阵排列的准正方形银纳米颗粒阵列结构。     

基于电泳法和磁控溅射技术制备金纳米阵列

采用纳米球刻蚀技术中的电泳法设计了3组对照实验,通过控制电压、悬浮液的体积分数和基板正负极性,得到电泳法制备纳米球掩膜板的最佳条件,制备出排布均匀的纳米球单层密堆积结构的掩膜板.采用磁控溅射技术在掩膜板上沉积金薄膜,去除纳米球掩模板,通过扫描电子显微镜观察到周期排列的三角形棱台状金纳米颗粒阵列.测量其吸收光谱,可观察到表面等离子体共振吸收峰.     

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.     

聚苯乙烯多孔薄膜的密度梯度控制

利用单分散的SiO2微球自组装制备了含一种尺寸微球的SiO2胶体晶体和含多种尺寸微球的多层异质结构。对含一种尺寸微球的SiO2胶体晶体进行煅烧和刻蚀处理后,胶体晶体中空隙所占比例大于立方密堆结构的26%,形成了非密堆结构,而且刻蚀时间越长,空隙比例越大。在同样的热处理和刻蚀条件下,微球尺寸越小的胶体晶体被刻蚀的程度越高,结构中空气空隙所占的比例越大。对SiO2多层异质结构经过煅烧和刻蚀处理后,得到了空隙梯度变化的多层结构,以此为模板制备了密度梯度变化的聚苯乙烯多孔薄膜。薄膜各层之间形成了平滑的过渡,没有显示出明显的层间缺陷,且孔与孔之间没有出现3维有序多孔结构中常见的大的连通孔道。     

有序金纳米颗粒阵列的制备及光吸收特性研究

采用纳米球刻蚀技术中漂移法在玻璃基片上制备较大 面积不同直径的聚苯乙烯小球掩模板, 采用磁控溅射技术在掩模板上沉积不同厚度的金薄膜, 去除聚苯乙烯小球后, 通过扫描电子显微镜观察到周期排列的三角状金纳米颗粒点阵. 通过紫外-可见分光光度计测试所制备样品的光吸收特性, 发现表面等离子体共振峰随粒径增大发生红移, 随金纳米颗粒高度增加发生蓝移. 基于Mie理论, 利用Matlab软件编程对不同粒径的金阵列光吸收特性进行理论模拟, 并与实验结果进行对比. 关键词： 纳米球刻蚀 金纳米颗粒阵列 表面等离子体共振     

中红外仿生复合微纳结构减反射表面研究

利用原子层沉积技术共形生长的特点,同时利用自组装掩模刻蚀技术,在单晶硅基底上制备了具有低深宽比和满占空比特点的Al₂O₃-Si复合微纳结构表面。光谱反射率测试结果表明,在底端满占空比、微结构深宽比接近1:1的情况下,入射角在8°时复合微纳结构表面在3～5μm谱段的平均反射率小于3.5%。纳米压痕测试结果表明,Al₂O₃-Si复合微纳结构表面的弹性恢复率较单一硅基底结构增加10.14%,证明沉积氧化铝薄膜具有提升抗反射微纳结构力学性能的作用。     

电阻热蒸发镀膜与电子束蒸发镀膜对纳米球刻蚀方法制备二维银纳米阵列结构的影响

在使用纳米球刻蚀法制备二维银纳米点阵的过程中,使用不同的镀膜方法在同样的模板上得到了不同形貌的银纳米阵列结构.使用电阻热蒸发镀膜方法获得了六角排列的银纳米三角形阵列结构,使用电子束蒸发镀膜方法则获得了六角排列的银纳米环阵列结构.研究表明,沉积纳米粒子的粒径、表面纳米曲率效应和热能是形成不同结构形貌的纳米阵列结构的关键因素. 关键词： 银纳米阵列 电阻热蒸发 电子束蒸发 纳米球刻蚀     

Tuning a nano-pillar array for enhancing the photoluminescence extraction efficiency of GaN-based light-emitting diodes

We demonstrate the fabrication of hexagonal nano-pillar arrays at the surface of GaN-based light-emitting diodes (LEDs) by nanosphere lithography. By varying the oxygen plasma etching time, we could tune the size and shape of the pillar. The nano-pillar has a truncated cone shape. The nano-pillar array serves as a gradual effective refractive index matcher, which reduces the reflection and increases light cone. It is found that the patterned surface absorbs more pumping light. To compare extraction efficiencies of LEDs, it is necessary to normalize the photoluminescence power spectrum with total absorption rate under fixed pumping power, then we could obtain the correct enhancement factor of the photoluminescence extraction efficiency and optimized structure. The highest enhancement factor of the extraction efficiency is 10.6.     

Controlling SERS intensity by tuning the size and height of a silver nanoparticle array

It is demonstrated that the surface-enhanced Raman scattering (SERS) intensity of R6G molecules adsorbed on a Ag nanoparticle array can be controlled by tuning the size and height of the nanoparticles. A firm Ag nanoparticle array was fabricated on glass substrate by using nanosphere lithography (NSL) combined with reactive ion etching (RIE). Different sizes of Ag nanoparticles were fabricated with seed polystyrene nanospheres ranging from 430 nm to 820 nm in diameter. By depositing different thicknesses of Ag film and lifting off nanospheres from the surface of the substrate, the height of the Ag nanoparticles can be tuned. It is observed that the SERS enhancement factor will increase when the size of the Ag nanoparticles decreases and the deposition thickness of the Ag film increases. An enhancement factor as high as 2×10⁶ can be achieved when the size of the polystyrene nanospheres is 430 nm in diameter and the height of the Ag nanoparticles is 96 nm. By using a confocal Raman mapping technique, we also demonstrate that the intensity of Raman scattering is enhanced due to the local surface plasmon resonance (LSPR) occurring in the Ag nanoparticle array.     

Large-scale SiO2 photonic crystal for high efficiency GaN LEDs by nanospherical-lens lithography

Wafer-scale SiO2 photonic crystal （PhC） patterns （SiO2 air-hole PhC, SiO2-pillar PhC） on indium tin oxide （ITO） layer of GaN-based light-emitting diode （LED） are fabricated via novel nanospherical-lens lithography. Nanoscale polystyrene spheres are self-assembled into a hexagonal closed-packed monolayer array acting as convex lens for expo- sure using conventional lithography instrument. The light output power is enhanced by as great as 40.5% and 61% over those of as-grown LEDs, for SiO2-hole PhC and SiO2-pillar PhC LEDs, respectively. No degradation to LED electrical properties is found due to the fact that SiO2 PhC structures are fabricated on ITO current spreading electrode. For SiO2- pillar PhC LEDs, which have the largest light output power in all LEDs, no dry etching, which would introduce etching damage, was involved. Our method is demonstrated to be a simple, low cost, and high-yield technique for fabricating the PhC LEDs. Furthermore, the finite difference time domain simulation is also performed to further reveal the emission characteristics of LEDs with PhC structures.     

Effect of chromium interlayer deposition on periodic silver nanoparticle array structure fabricated by nanosphere lithography

Effect of chromium interlayer deposition on 2-dimensional, periodic silver nanoparticle array structure was systematically investigated. The silver nanoparticle array was fabricated by nanosphere lithography with assembled polystyrene nanospheres being as a deposition mask. The chromium interlayer was deposited by thermal evaporation either on the nanosphere mask or directly on the silicon substrate. The structures of the achieved silver nanoparticle arrays were characterized by scanning electron microscope and were compared with that of silver nanoparticle array without the interlayer. With analysis of the anomalies among the structures the critical role of the interlayer in the periodic nanoparticle array fabrication was revealed.     

Versatile nanosphere lithography technique combining multiple-exposure nanosphere lens lithography and nanosphere template lithography

A versatile nanosphere composite lithography(NSCL) combining both the advantages of multiple-exposure nanosphere lens lithography(MENSLL) and nanosphere template lithography(NSTL) is demonstrated. By well controlling the development, washing and the drying processes, the nanosphere monolayer can be well retained on the substrate after developing and washing. Thus the NSTL can be performed based on MENSLL to fabricate nanoring, nanocrescent and hierarchical multiple structures. The pattern size and the shape can be systemically tuned by shrinking nanospheres by using dry etching and adjusting the tilted angle. It is a natural nanopattern alignment process and possesses a great potential in the scope of nano-science due to its low cost,simplicity, and versatility for variuos nano-fabrications.     

Silicon nanotips formed by self-assembled Au nanoparticle mask

The Au nanoparticle monolayer is formed by self-assembly technology on the Si substrates terminated with different functional groups. Silicon nanotips were fabricated by a self-assembled gold colloidal particle monolayer as an etch mask. The silicon nanotips with high density and uniformity in height and shape were obtained using reactive ion etching (RIE). The Si nanotips on the surface of the 3-aminopropyltrimethoxysilane (APTMS)-treated Si substrate are less-ordered array and uniformity than 3-mercaptopropyltrimethoxysilane (MPTMS)-treated Si substrate at the same etching conditions. The ordered array and uniformity of Si nanotips on the APTMS-modified Si substrate was improved through heat-treatment. This result is implied the different functional groups on the Si surfaces could affect the formation of the Si nanostructures during RIE process. The uniformly nanotip pattern with height of >20 nm is obtained on the etched nanoparticle-coated Si substrate. This method can be applied to patterning a wide variety of thin film materials into tip arrays.     

Formation of three‐dimensional GaAs microstructures by combination of wet and metal‐assisted chemical etching

Previously, plasma‐enhanced dry etching has been used to generate three‐dimensional GaAs semiconductor structures, however, dry etching induces surface damages that degrade optical properties. Here, we demonstrate the fabrication method forming various types of GaAs microstructures through the combination etching process using the wet‐chemical solution. In this method, a gold (Au)‐pattern is employed as an etching mask to facilitate not only the typical wet etching but also the metal‐assisted chemical etching (MacEtch). High‐aspect‐ratio, tapered GaAs micropillars are produced by using [HF]:[H₂O₂]:[EtOH] as an etching solution, and their taper angle can be tuned by changing the molar ratio of the etching solution. In addition, GaAs microholes are formed when UV light is illuminated during the etching process. Since the wet etching process is free of the surface damage compared to the dry etching process, the GaAs microstructures demonstrated to be well formed here are promising for the applications of III–V optoelectronic devices such as solar cells, laser diodes, and photonic crystal devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Profile calculation of gold nanostructures by dispersed-nanosphere lithography through oblique etching for LSPR applications

Nanosphere lithography is an inexpensive method used to fabricate gold nanostructures on a substrate. Using dispersed-nanosphere lithography, in which the nanospheres are dispersed on a substrate, 2D or 3D nanostructures can be fabricated by obliquely depositing a gold film on the nanospheres and etching the gold film afterward. These nanostructures are tunable and acute, and are thus good emitting elements for the localized surface plasmon resonance applications. So far, for the fabrication of nanostructures on a substrate with dispersed nanospheres, only 2D nanostructures have been reported through perpendicular etching. We report in this paper that the 3D nanostructures fabricated by dispersed-nanosphere lithography are rigid non-conformal structures, and perpendicular gold etching can be expanded to oblique etching, which provides more possibilities for fabricating the gold nanostructures in various shapes. The profiles of gold nanostructures after several varying angle depositions, and their final profiles after perpendicular or oblique etching, are calculated in this paper. Our profile simulations are applicable for nanospheres (or microspheres) within the range of tens of nanometers to tens of micrometers, and are consistent with our fabricated nanostructures observed using scanning electron and atomic force microscopy. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Fabrication of the uniform CdTe quantum dot array on GaAs substrate utilizing nanoporous alumina masks

Fabrication of quantum dot array (QDA) is attractive for applications in electronic and optoelectronic devices. The CdTe QDAs have potential applications in optoelectronic devices of visible range. One of the major challenges in fabricating QDAs is the uniformity and reproducibility in size and spatial distribution. The uniformity and reproducibility of QDs can be improved by using the nanoporous alumina mask. The geometry of porous alumina is schematically represented as a close-packed array of columnar hexagonal cells, each containing a central pore normal to the substrate. The well-ordered nanoporous alumina masks were able to obtain by two-step anodizing processes from aluminum in oxalic acid solutions at low temperature. The pore size, thickness, and density of nanoporous alumina mask can be controlled with the anodization voltage, time, and electrolyte. The CdTe QDAs on the GaAs substrate was grown by molecular beam epitaxy method using the porous alumina masks. The temperature of substrate and source (Cd, Te) was an important factor for the growth of CdTe QDs on GaAs substrate. The CdTe QDAs of 80 nm dot size was fabricated; using the porous alumina masks (300 nm thickness) of pore diameter (80 nm) and density (10¹⁰ /cm²).