Real‐Time Probing Nanopore‐in‐Nanogap Plasmonic Coupling Effect on Silver Supercrystals with Surface‐Enhanced Raman Spectroscopy

Nanopore structures have displayed attractive prospects in diverse important applications such as nanopore‐based biosensors and enhanced spectroscopy. However, on the one hand, the fabrication techniques to obtain sub‐10 nm sized nanopores so far is very limited. On the other hand, the electromagnetic enhancement of nanopores is still relatively low. In this work, using a facile chemical etching strategy on 2D plasmonic Ag nanoparticle supercrystals, fine nanopore arrays with sub‐10 nm pore size have been successfully fabricated and a “nanopore‐in‐nanogap” hybrid plasmon mode has been investigated. An in situ etching and surface‐enhanced Raman spectroscopy (SERS) detection indicate that novel hybrid plasmon structure may create an enhanced electromagnetic coupling and increase SERS signal at ≈10× magnification. The breaking of plasmon bonding dipolar mode and generation of antibonding‐like plasmon mode contribute to this enhanced electromagnetic coupling. The facile etching strategy, as a common approach, may open the doors for the fabrication of nanopores in various compositions for numerous applications.     

微波印制电路板加工工艺探索

本文主要结合当下微波通讯技术的迅猛发展——微波通讯设备日趋模块化、小型化、高密度化,简要阐述了微波印制电路板及其制作优势和缺点,如基材选用多样化、设计与制造的高精度化等.就微波印制电路板加工工艺,分别从选材、对生产环境适应性的要求、合理选用工艺流程、工程材料的处理和下料、钻孔和导通孔接地、图形转移、蚀刻与涂镀以及成型等方面进行了详细探讨.     

Surface etching of 6H-SiC (0001) and surface morphology of the subsequently grown GaN via MOCVD

The correlation between surface morphological properties of the GaN epilayers and the surface conditions of 6H-SiC (0001) substrates etched in H₂, C₂H₄/H₂, and HCl/H₂ was studied. Etching 6H-SiC in H₂ produced a high quality surface with steps and terraces, while etching in HCl/H₂ produced either a rough surface with many pits and hillocks or a smooth surface similar to that etched in H₂, depending on the HCl concentration and temperature. The GaN epilayers were subsequently deposited on these etched substrates using either a low temperature GaN or a high temperature AlN buffer layer via MOCVD. The substrate surface defects increased the density and size of the “giant” pinholes (2–4 μm) on GaN epilayers grown on a LT-GaN buffer layer. Small pinholes (<100 nm) were frequently observed on the samples grown on a HT-AlN buffer layer, and their density decreased with the improved surface quality. The non-uniform GaN nucleation caused by substrate surface defects and the slow growth rate of planes of the islands were responsible for the formation of “giant” pinholes, while the small pinholes were believed to be caused by misfit dislocations.     

测定硅各向异性腐蚀速率分布的新方法

介绍了一种测定硅各向异性腐蚀速率分布的新方法.硅各向异性腐蚀速率三维分布可由一系列晶面上的二维腐蚀速率分布表示.利用深反应离子刻蚀技术(DRIE)在{0mn}硅片上制作出侧壁垂直于硅片表面的矩形槽,测量槽宽度在腐蚀前后的变化,就可测定各{0mn}面上的二维腐蚀速率分布.将二维腐蚀速率分布组合在一起就得到了三维腐蚀速率分布.由于DRIE制作的垂直侧壁深度大,可耐受较长时间的各向异性腐蚀,所以只需使用一般的显微镜就能得到准确的结果.实验得到了40%KOH和25%TMAH中{n10}和{n11}晶面的腐蚀速率分布数据     

铌酸锂干法刻蚀的研究进展

概述了近年来国内外对铌酸锂(LN)晶体干法刻蚀技术的研究进展。根据刻蚀原理和特点,现有的LN干法刻蚀技术可分为等离子体刻蚀、激光微加工技术和Ti扩散电化学刻蚀。对各刻蚀方法及其研究进展进行了总结,分析了不同干法刻蚀方法之间的区别和联系,并对各方法中存在的问题进行了探讨。其中等离子体刻蚀技术由于其良好的图形转移特性,得到了最广泛的应用;激光微加工技术在制备光子晶体结构和微光栅结构中具有独特的优势;Ti扩散电化学刻蚀LN为制备大尺寸的LN基结构指明了新的方向。     

聚酰亚胺微刻蚀加工工艺研究

研究了RIE刻蚀聚酰亚胺的刻蚀速率、刻蚀表面粗糙度与不同加工工艺参数(包括射频功率、腔室压力、刻蚀气体成分等)之间的相互关系。刻蚀速率与射频功率、腔室压力都呈线性关系,与气体成分的关系是低SF6含量时呈线性,高SF6含量时出现饱和。刻蚀面的粗糙度几乎不受腔室压力的影响,而射频功率高于300 W和低SF6含量时粗糙度会急剧上升。采用腔室压力40 Pa、功率275 W、O2流量80 cm3/min、SF6流量20 cm3/min,通过RIE刻蚀获得了深度为39.5μm的微腔结构,为形成柔性基底空腔以及上悬结构等提供了技术基础。此外,对柔性基底固定技术进行了研究,提出了一种有效固定聚酰亚胺膜的新工艺方法。     

台槽刻蚀对埋栅型静电感应晶体管特性的影响

对埋栅型SIT,为切断栅极和源极（或阴极）之间在外延过程中形成的连体,打开栅电极区,进行外延后的台面刻蚀,对台面刻蚀的深度和形状进行研究;为消除栅墙外划片边界造成的各种寄生效应,在有源区的外面挖深槽,以保证栅源击穿发生在内部、实现击穿接近理论值。对先刻蚀台面还是先刻蚀槽的问题做了实验对比,结果发现先台后槽更有利于器件特性的改善。     

CuIn1−xGaxSe2‐based thin‐film solar cells by the selenization of sequentially evaporated metallic layers

Polycrystalline CuIn_1−xGa_xSe₂ (CIGS) thin films were deposited by the non‐vacuum, near‐atmospheric‐pressure selenization of stacked metallic precursor layers. A study was carried out to investigate the influence of significant factors of the absorber on the solar cells performance. An efficiency enhancement was obtained for Cu/(In+Ga) atomic ratios between 0·93 and 0·95. The slope of the observed energy bandgap grading showed a strong influence on the V_OC and the short circuit current density J_SC. An increase of the Ga content in the active region of the absorber was achieved by the introduction of a thin Ga layer on the Mo back contact. This led to an improvement of efficiency and V_OC. Furthermore, an enhanced carrier collection was detected by quantum efficiency measurements when the absorber layer thickness was slightly decreased. Conversion efficiencies close to 10% have been obtained for these devices. Copyright © 2005 John Wiley & Sons, Ltd.     

Selective and nonselective wet etching of Zn0.9Mg0.1O/ZnO

Wet etch rates at 25°C for Zn_0.9Mg_0.1O grown on sapphire substrates by pulsed laser deposition (PLD) were in the range 300–1100 nm · min⁻¹ with HCl/H₂O (5×10⁻³−2×10⁻² M) and 120–300 nm · min⁻¹ with H₃PO₄/H₂O (5×10⁻³−2×10⁻² M). Both of these dilute mixtures exhibited diffusion-limited etching, with thermal activation energies of 2–3 kCal · mol⁻¹. By sharp contrast, the etch rates for ZnO also grown on sapphire by PLD were much slower in similar solutions, with rates of 1.2–50 nm · min⁻¹ in HCl/H₂O (0.01–1.2 M) and 12–54 nm · min⁻¹ in H₃PO₄/H₂O (0.02–0.15 M). The etching was reaction limited over the temperature range 25–75°C, with activation energies close to 6 kCal · mol⁻¹. The resulting selectivity of Zn_0.9Mg_0.1O over ZnO can be a high as ∼400 with HCl and ∼30 with H₃PO₄.     

多层纳米微结构的制备与陷光机理研究

采用电化学腐蚀方法在单晶硅片表面制备了折射率渐变的多层纳米微结构。用扫描电镜和UV-VIS-NIR分光光度计分别分析了多层纳米微结构的表面形貌和反射率。研究了腐蚀电流密度和腐蚀时间对微结构减反射性能的影响并分析了多层纳米微结构的陷光机理。结果表明:硅片表面的纳米孔径随着腐蚀电流密度和腐蚀时间增加而增大,初始腐蚀电流密度为12.25mA/cm2和腐蚀时间为2s时,表面最大的纳米孔径为30nm,在400nm～800nm的可见光波长范围内的反射率为3.4%,在200 nm～2000nm的宽波长范围内反射率仅为5.8%,远小于常规金字塔对应的反射率。这种宽波段范围的低反射率来源于多层纳米微结构中邻层相差很小的等效折射率。