纳米器件的一种新制造工艺——纳米压印术

纳米压印术可以用于大批量重复性地制备纳米图形结构。此项技术具有操作简单、分辨率高、重复性好、费时少,成本费用极低等优点。本文介绍了较早出现的软刻印术的两种方法———微接触印刷法和毛细管微模制法。详细讲述了纳米压印术(主要指热压雕版压印法)的各步工序———压模制备、压印过程和图形转移,以及用于压印的设备、纳米图案所达到的精确度等,还简述了纳米压印术的另一方法———步进-闪光压印法。最后,通过范例介绍了纳米压印术在制作电子器件、CD存储器和磁存储器、光电器件和光学器件、生物芯片和微流体器件等方面的应用。     

宽波长太阳能电池抗反射层结构设计

为了降低太阳能电池表面对入射光的反射,提高其光电转换效率,设计了入射光谱在400～1100 nm宽波长范围内的二维亚微米抗反射层结构.该结构主要由高折射率ZnS膜层、低折射率MgF_2膜层及二维亚微米光栅层等组成.采用严格耦合波分析理论计算了此结构的反射特性,当ZnS膜层、MgF_(2)膜层、光栅深度及光栅周期分别为50 nm、150 nm、200 nm及400 nm,入射角在0～80°变化时,其平均反射率为7.76%.计算结果表明:所设计的抗反射层结构可有效降低太阳能电池表面对入射光的反射,从而提高其光电转换效率.     

Rapid fabrication of ultraviolet-cured polymer microlens arrays by soft roller stamping process

This paper reports an innovative technique for rapid fabrication of ultraviolet-cured polymer microlens arrays based on soft roller stamping process. In this method, a soft roller with microlens array cavity is made by casting a pre-polymer of polydimethylsiloxane (PDMS) in a plastic master of microlens array. The plastic master is prepared using gas-assisted hot embossing of polycarbonate (PC) film over a silicon mold with micro-holes array. The microlens array cavity on the soft roller is filled with liquid UV curable polymer first. The roller rolls and stamps over the traveling transparent substrate. The microlens array pattern is formed. At the same time, the pattern on the substrate is cured by the UV light radiation while traveling through the rolling zone.In this study, a roller stamping facility with UV exposure capacity has been designed, constructed and tested. The replication quality, surface roughness and optical property of the replicated microlens arrays are measured, analyzed and proved satisfactory. This study demonstrates the potential of soft roller stamping for continuous rapid mass production.     

Low-temperature embossing technique for fabrication of large-area polymeric microlens array with supercritical carbon dioxide

This study reports an effective process for low temperature replication of polymeric microlens array using carbon dioxide (CO₂) as softening solvent and then as embossing pressure. Supercritical CO₂ is employed to soften the surface of polymer substrate and then apply pressure on it. Accordingly, microlens can be formed on the polymer substrate at low temperature. Using gas as embossing pressure can provide uniform pressure for large-area replication. During the embossing process, an array of convex microlenses is generated by partial protrusion of the substrate into the micro-holes of the mold under the action of embossing pressure and surface tension. The uniformity of large-area fabrication and optical property of the fabricated refractive microlens array on a 260 mm × 110 mm poly (methyl methacrylate) (PMMA) substrate have been verified. Little residual stress can be observed by polariscope. With the proposed method, the large-area embossing can be performed without heating and cooling. Moreover, the problems of non-uniform pressure and residual stress can be overcome.     

基于反射光谱的单层抗反射膜的非在位膜厚精确控制

提出一种基于反射光谱分析的非在位膜厚控制技术,首先利用椭圆偏振光谱仪确定波长300～1 700 nm范围内的薄膜折射率,由此确定对应于特定波长(如1 550 nm)的最佳抗反射(AR)镀膜沉积条件。然后计算最佳AR镀膜厚度所对应的反射谱,得到相应的CIE标准色谱坐标。通过对比实测镀膜颜色和计算得到的最佳颜色,可以实现小尺寸器件端面上AR镀膜厚度的优化控制。利用这一方法,由等离子体增强化学气相沉积(PECVD)制备的SiNx单层AR镀膜,获得了4.4×10-4的反射率。     

新型亚波长光栅横向腔面发射激光器

本文报道一种新型的横向腔面发射激光器,基于亚波长光栅平面内的横向谐振与垂直发射。器件采用不含DBR结构的商用波导外延材料,不需要晶片键合技术。在1552.44 nm处获得了23.0 dB的边模抑制比,最高输出功率5.32 mW。此单模激射与带边模式计算相吻合。在3维的模拟中,我们观察到光栅表面的光输出。     

Fabrication of gold sub-wavelength pore array using gas-assisted hot embossing with anodic aluminum oxide (AAO) template

This paper reports a novel and effective method for the fabrication of gold sub-wavelength pore array using gas-assisted hot embossing. The novel fabrication comprises the fabrication of AAO template with high order pore array, sputter-coating of gold and gas-assisted hot embossing. AAO template is fabricated by a two-step anodization process. It is then coated with gold (100 nm thick). The gold sub-wavelength pore array is finally formed by using gas-assisted hot embossing process. The transmission spectra of gold sub-wavelength pore array are measured in several conditions such as air, water and glycerol/water mixture. The detection shows significant shift in the wavelength of resonance peak. The gold sub-wavelength pore array can be employed as optical biosensors.     

Wafer-scale fabrication of magneto-photonic structures in Bismuth Iron Garnet thin film

In this paper we report on a reproducible technological process for wafer-scale fabrication of different photonic structures in Bismuth Iron Garnet (BIG: Bi₃Fe₅O₁₂) thin films: two-dimensional magneto-photonic crystals (PhC), ring circulators, Bragg gratings or ridge waveguides. Different fabrication techniques such as Ion Beam Etching (IBE), Focused Ion Beam (FIB) etching, wet chemical etching and Reactive Ion etching are compared. The transfer of different geometries in BIG is obtained with good etching verticality and conservation of the dimensions using Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). This work demonstrates the possibility of wafer-scale high-quality nanostructuration of crystalline garnet thin films for magneto-photonic devices.     

微流控芯片热压键合设备的结构设计

以塑料微流控芯片的热压加工技术为基础,以实现自动化和批量化为目标,对芯片热压键合设备的机械结构进行设计研究,在保证芯片受压均匀的情况下,对设备机身的结构、加压方式等进行了分析,确定设备机身采用闭式双立柱结构,上部加压方式,通过力矩电机、螺旋升降机带动压头完成压力输出,并对压头的运动进行导向。实验表明,在热压芯片时,该设备能够将优化的工艺参数复现,制作的芯片质量稳定,一致性好。     

Interfacial adhesion of spin-coated thin adhesive film on silicon substrate for the fabrication of polymer optical waveguide

An investigation was carried out to study the interfacial adhesion of spin-coated polymeric adhesive thin film on a silicon substrate for fabrication of a polymeric optical waveguide. An adhesive shear button was made on a silicon substrate by using a photolithography process, and interfacial adhesion was measured with a Dage D2400 shear tester. Different adhesion strengths were found at different portions of the same sample. Higher adhesion strength was observed at the center of the substrate than at other locations of spin-coated adhesive films. Adhesion strength was also measured after heat exposure of the deposited and cured adhesive layer to evaluate the heat resistance of the adhesive film. After heat exposure, adhesion strength decreased substantially from all locations of the substrate due to the thermal degradation. Again, the adhesion was measured for different plasma-treated substrate conditions. The surface morphology of plasma-treated and untreated silicon substrates before deposition were characterized by atomic force microscopy. Lower adhesion strength was unexpectedly observed for all plasma-treated substrates, even for higher surface roughness. The fracture surfaces after shear testing were also characterized by optical microscopy. The complete study provides important indications for the fabrication of better-performing polymeric optical waveguides for photonic devices.     

An optimum approach for fabrication of tapered hemispherical-end fiber for laser module packaging

Comprehensive measurements of the dependence of coupling efficiency and radius of curvature on taper angle in a tapered hemispherical-end fiber (THEF) for coupling between laser diodes and single-mode fibers are presented. The THEF was fabricated by etching the fiber end in a hydrofloride (HF) solution with a thin layer of oil floating on top of the HF, and then heating in a fusion splicer to form a hemispherical end. The results show that THEFs with larger taper angles fabricated by greater oil density exhibit a smaller radius of curvature, and hence a better coupling efficiency. The results of this investigation have led to an optimum approach for high-yield and high-volume fabrication of THEFs that is suitable for use in commercial laser diode modules for efficient coupling between laser diodes and single-mode fibers. The calculation of the effect of oil density in HF etching solution on taper angle based on a semiempirical model is in good agreement with the measured results.     

A novel fabrication approach for an athermal arrayed-waveguide grating

A novel method for fabricating an athermal AWG is proposed, using a unique apparatus for ITU-T center wavelength adjustment and optical coupling of two cut-parts. UV adhesive or sticky gel is applied into the gap between the cut-elements and the alignment base substrate by capillary infiltration. The spectrum profiles are almost the same as those of the original chip state, and no deterioration is observed resulting from athermalization. Flat-top athermal AWG modules of 100 GHz×40 ch are fabricated. Over a temperature range of-40 to 85℃, the center wavelength shift is±22 pm, and the insertion loss change is less than ±0.11 dB.     

无热阵列波导光栅的新颖制作方法

提出了一种制作无热AWG的新颖方法,采用了专利设计的ITU-T中心波长调节装置、简单的方法来耦合被切开两部分、以及毛细渗透的点胶方式。波长调节精度达到1pm。这种无热实现方案没有带来任何光谱恶化,其光谱几乎同原始芯片一样。这种40通道100GHz通道间隔平顶型无热AWG,在-40 to 85℃范围内,中心波长漂移±22pm,插损变化小于±0.11dB。     

Spray coating methods for polymer solar cells fabrication: A review

The main focus of this review article is the introduction of relevant parameters in spray coating processes to provide better understanding on controlling the morphology of spray coated thin films for producing high performance polymer solar cells (PSC). Three main parameters have been identified as major influences on the spray coating processes. These are nozzle to substrate distance, solvent and mixed solvents effects, and substrate temperature and annealing treatment. Such spray coating techniques show great potential for large scale production, since these methods have no limitation in substrate size and low utilization of polymers which is promising to substitute the conventional spin coating methods. Currently available printing and coating methods are also briefly discussed in this review.     

Controlling resist thickness and etch depth for fabrication of 3D structures in electron-beam grayscale lithography

In many applications such as optoelectronic devices, three-dimensional (3D) structures are required. Examples include photonic band gap (PBG) crystals, diffractive optical elements, blazed gratings, MEMS, NEMS, etc. It is known that the performance characteristics of such structures are highly sensitive to their dimensional fidelity. Therefore, it is essential to have a fabrication process by which such 3D structures can be realized with high dimensional accuracy. In this paper, practical methods to control thickness of the remaining resist and etch depth, which may be employed for fabrication of such 3D structures using grayscale electron-beam lithography, are described. Through experiments, explicit control of the remaining resist thickness and etch depth at the resolution of 20 nm for the feature sizes of 0.5 μm and 1 μm has been successfully demonstrated. Also, the 1:1 ratio of silicon to resist etching rates was achieved for transferring the remaining resist profile onto the silicon substrate.     

A novel technology for fabrication of beam-leaded GaAs Schottky-barrier mixer diodes

The fabrication of mixer diodes for use at millimeter-wave frequencies requires the definition of extremely small area Schottky-barrier junctions. It is not a trivial matter to fabricate such devices at low cost which simultaneously are mechanically rugged, exhibit low parasitics, and present high figures of merit. This paper presents a novel technology for accomplishing these objectives. By incorporating "shadow masked" proton bombardment and metal evaporation, planar beam-leaded devices of low capacitance are realized in the absence of the critical processing steps which have traditionally resulted in low yields. GaAs devices having zero bias capacitance of 0.06 pF are obtained with a series resistance of less than 3 Ω giving a cutoff frequency in excess of 800 GHz. Initial RF tests have resulted in a noise figure and conversion loss of 5.8 and 3.8 dB, respectively, at 10.7 GHz. This technology should result in the availability of inexpensive GaAs mixer diodes suitable for use at millimeter-wave frequencies.     

A novel laser direct write technique for fabrication of thin filmMICs

A technique for fabrication of thin-film circuits for microwave integrated circuit (MIC) application is presented. This low-cost fabrication technique utilizes laser direct write of copper patterns on alumina substrates. The method obviates the need for photomasks and photolithography. The film deposition mechanism, deposit film analysis, and MIC fabrication sequence are presented. Performance evaluation of MICs fabricated using this technique is also included     

硅微纳结构及其在新型太阳电池中的应用

综述了近年来各种硅微纳结构的特征和制备技术,介绍了其在新型太阳电池中的应用现状与前景.首先,阐述了硅微纳结构在传统p-n结、新型径向p-n结以及异质结太阳电池结构设计中的研究进展;其次,从光吸收增强、表面修饰及钝化的角度,分析了硅微纳结构太阳电池的增效措施;最后,提出了柔性硅微纳结构太阳电池开发的新思路.     

A micromachined, shadow-mask technology for the OMVPE fabrication of integrated optical structures

A micromachined, silicon shadow-mask technology is described which extends the capabilities of shadow-masked OMVPE for the fabrication of nonplanar micro-optical elements. The deep reactive ion etched (DRIE) shadow mask is inexpensive, reusable and produces smooth, nonplanar structures with precise control of position, shape and size. Direct fusion bonding of the mask to the substrate was found to be a reliable and reproducible method for attaching the mask to the substrate during growth. The DRIE shadow mask technology allows the deposition of microlenses with focal lengths out to 3 mm without the central flattening that was previously observed in shadow masked lenses grown under the epitaxial mask. We also describe novel applications of this technology in the fabrication of micromirrors and concentrically-variable Bragg reflectors, which should improve mode discrimination in large aperture VCSELs.