激光直写制备金属与碳材料微纳结构与器件研究进展

激光直写技术作为一种新兴的低成本、高效、高精度的加工技术,可以适用于几乎任意自由度的二维或者三维微纳结构快速成型制备.这对光电子以及半导体微纳结构与器件的制备具有重大的意义.金属微纳结构在电子学和光子学中有着广泛的应用.本文综述了激光直写制备金属微纳结构相关研究进展.主要包括激光直写制备金、银、铜以及复合材料微纳结构与...     

秒激光双光子微纳加工技术及其在光子学微器件制备中的应用

飞秒激光可以与包括玻璃、陶瓷、半导体、金属、塑料、树脂等各类物质产生相互作用,其相互作用原理不同,加工方法也不同。利用非线性光学效应——双光子吸收的飞秒微纳加工技术是最独特也是最具有应用前景的微纳加工技术。利用显微物镜将飞秒激光聚焦到加工介质时激光光强在焦点处呈三维空间分布,双光子吸收过程仅产生在具有足够激光强度的微小区域,通过控制激光光强可以调节双光子吸收的产生范围,在适当的激光强度时,可以突破光学衍射极限的限制,将双光子吸收过程控制到远小于激光波长甚至纳米尺度范围,从而达到进行纳米加工的目的。飞秒激光双光子微纳加工技术具有真三维、一次成型及高加工分辨率的特点,是三维微纳结构制备的理想工具之一。通过“理论计算-计算机辅助图形设计-微纳激光制造“这样一个简单的流程可以实现制备可设计的复杂三维微细结构,因此在光子学微器件、微机电系统等领域具有巨大的应用前景。最近几年双光子微细加工技术也已成功地应用到功能性光子学器件中。在制备基于光子晶体带隙原理的三维光子元器件及其立体集成方面,飞秒激光双光子方法具有无可比拟的优势。我们研究小组利用碳硅烷树状大分子修饰的激光染料与光聚合制备的光固化树脂,采用双光子聚合微加工技术制...     

银氧铯光电阴极的多光子光电产额

银氧铯光电阴极至今仍为一种重要的实用光电阴极,本文以银氧铯光电阴极为例,利用吴全德提出的有关模型和量子力学微扰论的结果,讨论了它的光强依赖关系,并导出了必要的公式;既为对实验结果的一种预测,也与现有实验结果符合很好。     

含银微纳米复合材料在生物医学应用的研究进展

近些年来,微纳米复合材料发展十分迅速。微纳米复合材料通常由两种或以上的不同材料组成在一个单元结构里,藉此具有多功能的、功能增强或协同增强的特性。含银微纳米复合材料是其中重要的研究分支,在当前生物医学应用中取得了众多的功能集成或功能增强等研究成果。主要综述了银/聚合物和银/氧化铁两类微纳复合材料,首先总结了银/聚合物和银/氧化铁微纳复合材料的制备方法,包括乳液聚合法、原位生成/还原法、空穴法、离子交换法、一锅法、种子法、静电作用法以及胶束法等;其次,总结了银/聚合物和银/氧化铁复合材料在表面增强拉曼散射、光学成像、抗菌抗癌、免疫检测、电化学检测、催化降解等生物医学领域的应用,以及对未来发展趋势的展望。     

玻璃包覆金属微丝的快速凝固制备及应用

玻璃包覆金属微丝具有耐蚀、耐高温、抗辐照及高绝缘性等特点,作为精密电子元器件用电磁线,具有重要的应用前景.综述了玻璃包覆金属微丝制备技术的发展现状、基本工艺原理、主要工艺参数以及玻璃包覆金属微丝材料的种类、微丝的形状尺寸与组织,介绍了玻璃包覆金属微丝在电气、电子工业以及复合材料制备等领域的用途.     

二维光子晶体微腔的制备及其对硅光学材料的光量子放大

光子晶体(PC)可以增加光物质相互作用和光发射效率,在微纳光子学、量子光学及信息光学等领域中都有着广泛的应用。近年来,二维硅基光子晶体微腔的发光增强效应研究取得了较为重大的突破。本文针对现有二维光子晶体及微腔的制备方法与发光性能的调控展开论述,详细介绍了二维光子晶体微腔的制备进程与温度、泵浦能量、微腔结构对微腔Q因子以及发光性能的影响,并进一步展望了二维光子晶体在硅材料光量子放大领域未来研究所面临的问题及应用前景。     

非晶无序光子晶体结构色机理及其应用

结构色是一种由光学尺度的微纳结构与光相互作用形成干涉、衍射或散射而产生颜色的物理生色效应。与化学生色不同,结构色由于没有色素或者染料的参与,因此没有颜色褪色的现象,同时能够避免使用染料和色素带来的环境污染。目前结构色材料受到研究者和应用开发人员的广泛关注,大量的研究发现结构色可以来源于光子晶体与非晶光子晶体两种结构。光子晶体由规整的周期性结构组成,产生的颜色鲜艳却具有明显的角度依赖性。而非晶光子晶体,其"自身缺陷"导致的短程有序结构具备了各向同性的光子带隙、非虹彩效应、光局域化等特点,赋予了材料柔和亮丽不随角度变化的显色效果,可控的激光效应以及优良的发光效率,从而更能满足材料领域对光散射和光传输等方面的特殊需求。对非晶光子晶体的概念和结构,与可见光作用产生颜色的原理,以及制备非晶光子晶体的不同方法(平板刻蚀法、胶体颗粒自组装法、模板法、相分离法)做了详细的讨论,并对非晶光子晶体产生的结构色效应在光电器件、功能涂料和纺织材料等多个领域中的应用进行了展望。     

太阳电池用金属背反镜的吸收损耗

利用频域有限差分法计算获得的金属背反镜吸收损耗谱及其光电流密度谱,分析了c-Si、a-Si和GaAs三种材料电池的银背反镜的吸收损耗情况。分析过程中,电池结构采用两种形式,即平板型和织构型,且两种形式的电池结构具有相同的有源层厚度、减反膜结构、缓冲层结构、银背反镜厚度。分析表明:直接带隙a-Si和GaAs材料的银背反镜损耗小于间接带隙c-Si材料;平板型电池银背反镜的TE模损耗随入射角增加而减小,TM模损耗随入射角增加而增加;织构型电池银背反镜吸收谱的吸收峰较平板型电池多,相应的银背反镜的损耗也较平板型电池大;TM模激励的等离子体振荡吸收效应在织构型电池中表现明显。     

表面微/纳米计量中的光学测量方法综述

微纳检测技术旨在以微/纳米级的精度测量加工表面特征,在加工过程的控制、建立表面特征与功能间的联系等方面具有重要作用。光学测量方法具有高精度、快速和无损的特点,是微纳检测技术研发的重要内容。本文介绍了表面形貌和薄膜的光学测量方法,并对各方法的特点及应用场合进行了对比总结。微纳制造技术加工的表面具有结构日益小型化、特征日益复杂化的特点,因此开发多模式测量系统是微纳检测技术的发展趋势。     

基于差动原理的双叉指电容式微纳力发生装置

微纳力的产生是微纳力量值溯源中的关键技术问题,而输入电压的不稳定性和装置卸载后的残余电容对电容式微纳力发生装置输出力值的准确性将产生较大影响。本文利用差动结构原理,将双叉指状电容结构应用于微纳力发生装置中,实现了在水平方向生成标准的微纳力值。经过与传统装置的比较分析表明:该装置能在不增加辅助设备的情况下,有效减少外部输入电压不稳定性以及残余电容引起的残余静电力对标准微纳力值输出的影响,为微纳力量值溯源装置的设计提供了有益的参考。     

Scalable Nanoshaping of Hierarchical Metallic Patterns with Multiplex Laser Shock Imprinting Using Soft Optical Disks

Large‐area patterning of metals in nanoscale has always been a challenge. Traditional microfabrication processes involve many high‐cost steps, including etching and high‐vacuum deposit, which limit the development of functional nanostructures, especially multiscale metallic patterns. Here, multiplex laser shock imprinting (MLSI) process is introduced to directly manufacture hierarchical micro/nanopatterns at a high strain rate on metallic surfaces using soft optical disks with 1D periodic trenches as molds. The unique metal/polymer layered structures in inexpensive soft optical disks make them strong candidates of molds for MLSI processes. The feasibility of MLSI on hard metals toward soft molds is studied using theoretical simulation. In addition, various types of hierarchical structures are fabricated via MLSI, and their optical reflectance can be modulated via a combination of depth (laser power density), width (types of molds), and angles (rotation between molds). The optical properties have been studied with surface plasmon polariton modes theory. This work opens a new way of manufacturing hierarchical micro/nanopatterns on metals, which is promising for future applications in fields of plasmonics and metasurfaces.     

Morphology modification of silver microstructures fabricated by multiphoton photoreduction

We have investigated the morphology modification of silver microstructures fabricated by the multiphoton photoreduction process. The microstructures have been fabricated by a femtosecond laser under different irradiation time and repeated scanning numbers. Trans-4-[4-(dimethylamino)-N-methylstilbazolium] p-tosylate (DAST) was used as photosensitizer and effectively reduced the laser power to 0.66 mW. The increase of the irradiation time and repeated scanning induced more reduction in the multiphoton photoreduction microfabrication process, resulting in the optimization of the linewidth. The fusion of silver nanoparticles was confirmed, which led to the morphology change of silver microstructures for achieving the compact metallic microstructures. The result would provide an important protocol to fabricate the metallic microstructures for the electronic and photonic applications.     

Preparation of nanosilver particles into sulfonated poly(ether ether ketone) (S-PEEK) nanostructures by electrospinning

By using the interaction between the sulfonated groups and silver ions, nanosilver particles were successfully introduced into S-PEEK nanostructures (nanospheres and nanofibers) by electrospinning. The nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectra (XPS), UV/vis, etc. The size of the spheres increases with the weight concentration of silver exchanged sulfonated poly(ether ether ketone) (S-PEEK-Ag) increasing. The size of the silver particles can be controlled by adjusting the sulfonated degree (number of sulfonate groups per repeating unit) of sulfonated poly(ether ether ketone) (S-PEEK) and the weight ratio of the S-PEEK solutions. This paper provides a new method for the preparation of nanometal particles into nanostructures.     

Femtosecond Photon‐Mediated Plasma Enhances Photosynthesis of Plasmonic Nanostructures and Their SERS Applications

Laser ablation in liquid has proven to be a universal and green method to synthesize nanocrystals and fabricate functional nanostructures. This study demonstrates the superiority of femtosecond laser‐mediated plasma in enhancing photoredox of metal cations for controllable fabrication of plasmonic nanostructures in liquid. Through employing upstream high energetic plasma during laser‐induced microexplosions, single/three‐electron photoreduction of metallic cations can readily occur without chemical reductants or capping agents. Experimental evidences demonstrate that this process exhibits higher photon utilization efficiency in yield of colloidal metal nanoparticles than direct irradiation of metallic precursors. Photogenerated hydrated electrons derived from strong ionization of silicon and water are responsible for this enhanced consequences. Furthermore, these metallic nanoparticles are accessible to self‐assemble into nanoplates for silver and nanospheres for gold, favored by surface‐tension gradients between laser irradiated and unirradiated regions. These metallic nanostructures exhibit excellent surface‐enhanced Raman spectroscopy performance in trace detection of Rhodamine 6G (R6G), 4‐mercaptobenzoic acid (4‐MBA), and mercapto‐5‐nitrobenzimidazole molecules with high sensitivity (down to 10^?12 mol L^?1, 30 × 10^?15 m for R6G), good reproducibility (relative standard deviation < 7%), and good dual‐analyte detection ability with mixture ratios of R6G to 4‐MBA ranging from 20 to 0.025. The conceptual importance of this plasma‐enhanced‐photochemical process may provide exciting opportunities in photochemical reactions, plasmofluidics, and material synthesis.     

Two- and three-dimensional micro/nanostructure patterning of CdS-polymer nanocomposites with a laser interference technique and in situ synthesis

Two-?and three-dimensional (2D and 3D) micro/nanostructures of CdS-polymer nanocomposites have been successfully patterned, combining photopolymerization via a laser four-beam interference technique with in situ synthesis of CdS nanoparticles in the patterned polymer matrix. The morphology and optical properties of CdS nanoparticles in polymer matrices have been confirmed using TEM, XRD, FTIR, UV-vis absorption and fluorescence spectroscopy. Laser irradiation time and film thickness are certified to be the key factors for the control of the micro/nanostructures. With thickening film, the fabricated microstructures of CdS-polymer nanocomposites were dramatically changed from 2D rods to 3D networks which were composed of nanofibres, nanometre-scale walls and micrometre-scale rods. These kinds of 2D and 3D micro/nanostructures could be expected as potential applications in the development of nanotechnology, such as nanomedical systems, micro-fluidic chips, nanoreactors and micro/nanopurification or separation systems.     

Material Characterization of Photo-Fabrication Process

The characterization of photopolymerization for the rapid prototyping process has been studied using a laser stereolithography machine. The cross sections of the cured layers and lines were examined using an optical microscope. Perkin-Elmer differential scanning calorimeter (DSC)-7 was employed to investigate the degree of curing after laser scanning. It was observed that the profile of the cross section of a cured line and/or part determined by the laser exposure density is a function of laser power and scanning speed. DSC analysis shows the retained resin to be governed by laser exposure intensity and laser scanning pattern. By increasing the laser exposure or the overlapping area of two adjacent scanning lines, retained and uncured resin could be minimized. However, the efficiency of photopolymerization is lowered. The most efficient operating parameters for part building can be determined by a T factor.     

Silver nano-inukshuks on germanium

The integration of metallic nanostructures with semiconductors is important for a variety of technological applications. Through an efficient galvanic displacement reaction on germanium, complex silver nanostructures form spontaneously in aqueous conditions at room temperature. The structures, termed nano-inukshuks, are based on stacks of hexagonal metallic structures that grow, initially, parallel to the surface normal of the germanium. TEM, SEM, XPS, XRD, and EDS indicate that the structures are crystalline silver and, based on open cell potential studies, that their nucleation takes place in the first 100 s, followed by growth of the silver structures, most likely through Volmer-Weber growth.     

Shape-controlled synthesis of PbCrO4 micro/nanostructures and their luminescent properties

PbCrO4 with different morphologies have been synthesized via a facile sonochemical route from an aqueous solution of lead acetate and potassium dichromate in the presence of nitrilotriacetate acid (H3NTA). The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The pH and the concentration of complexing reagent were found to have close relation with morphology of the final product. The possible growth mechanism of PbCrO4 microcube has been proposed. UV-Vis spectra and room-temperature photoluminescence of the PbCrO4 micro/nanostructures have also been investigated. Results showed that all the samples possessed strong photoluminescence (PL) properties, suggesting that the micro/nanostructures could be used in novel optoelectronic devices.     

Electrochemical nanoimprinting with solid-state superionic stamps

This letter presents a solid-state electrochemical nanoimprint process for direct patterning of metallic nanostructures. It uses a patterned solid electrolyte or superionic conductor (such as silver sulfide) as a stamp and etches a metallic film by an electrochemical reaction. Our preliminary experiments demonstrate repeatable and high-fidelity pattern transfer with features down to 50 nm on silver films of thicknesses ranging from 50 to 500 nm. As the process is conducted in an ambient environment and does not involve the use of liquids, it displays potential for single-step, high-throughput, large-area manufacturing of metallic nanostructures. The use of superionic conductors in manufacturing opens up a new and potentially energy-efficient approach to nanopatterning and fabrication. It offers a highly competitive approach, both as a stand-alone process and as a complement of other nanofabrication techniques, to fabricating chemical sensors, photonic and plasmonic structures, and electronic interconnects.