硫醇自组装多晶金表面AFM图像的分形研究

本文针对多晶粗糙电极表面自组装膜（SAM）体系,提出了利用原子力显微镜（AFM）相图分形维数进行表征的新方法。首先对自组装多晶金电极进行了交流阻抗测试,结果表明随着乙醇自组装液中十二烷基硫醇（C12SH）浓度增大,自组装膜中缺陷面积减少,趋向于形成完整致密的单分子层吸附膜。而对组装电极AFM图像的分形研究表明,在不同C12SH浓度条件下,电极表面高度图分形维数无明显变化,相图却呈现不同的分形特征,且体现的变化规律与交流阻抗测试结果一致,证实了AFM相图分形维数表征法研究粗糙金表面硫醇自组装膜吸附行为的可行性,为粗糙表面分子吸附行为的AFM研究提供了新思路。     

稀土La自组装纳米膜的制备及表征

电子封装表面材料采用分子自组装技术制备了稀土La纳米膜,采用AFM(原子力显微镜)对组装膜的表面形貌进行表征,表征结果该稀土纳米膜表面形貌致密,表面粒子尺寸为20～30nm;场发射扫描电镜测试表明,该组装膜的成分为La;     

复合自组装分子膜的摩擦特性研究

本文采用自组装技术制备了三氯十八硅烷(octadecyltrichorosilane 0TS)／3-胺基丙基-三甲氧基硅炕(3-amino-propyltrimethoxysilane APTMS)和APTMS／OTS复合自组装分子膜,在原子力／摩擦力显微镜上对薄膜的摩擦特性进行了测试,并与0TS和APTMS自组装分子膜(self-assembledmonolayers SAMs)进行了对比。结果表明,OTS／APTMS复合自组装分子膜因既保持了一定的键合强度叉增加了自组装分子的流动性,使其摩擦力显著降低。复合自组装分子膜的摩擦力随着载荷和滑动速度的增大而增大,这与自组装分子的受力响应和弛豫特性相关。合理地设计自组装分子膜可有效地减小摩擦。     

钝化剂自组装单层膜在铜铜键合工艺中的应用

解决铜铜键合工艺中的铜氧化问题对于三维集成技术具有重要意义。选用1-己硫醇做临时钝化剂,通过自组装形式形成单层膜附着于铜表面,以防止铜在存放时与空气接触而发生氧化,键合前再使用乙醇等有机溶剂去除该单层膜。为了评估1-己硫醇的钝化效果,采用接触角作为主要指标对实验结果进行评价。研究表明,样片表面经过1-己硫醇处理后,接触角极大增加,并在空气中长时间保持稳定,说明1-己硫醇具有良好的钝化效果,采用此方法得到了高质量的铜铜热压键合样片。     

Au(111)表面自组装硫醇单分子膜的STM成像机理

本文利用基于密度泛函理论的算法模拟Au(111)表面紧密堆构型的烷烃硫醇自组装单分子层膜(SAMs)中单分子的扫描隧道显微镜(STM)图像，发现图像细节依赖于偏压和烃链链长，主要由受电子效应影响的形貌效应决定。同时进行了电子结构分析以研究硫醇SAMs的STM成像机制，还发现烷烃硫醇分子中的S原子在Au表面的吸附模式也明显地影响着STM图像细节。     

ITO薄膜电极激光损伤形貌的多重分形研究

液晶光学器件中液晶分子的转动由施加在ITO薄膜电极间的电场来控制,ITO晶体结构中空穴和自由电子与强激光的相互作用,使ITO薄膜电极成为液晶光学器件结构中激光损伤的薄弱环节.为探索ITO薄膜电极的激光损伤机制,使用原子力显微镜(AFM)对厚度约为10nm的ITO薄膜的表面形貌进行了测量.采用多重分形理论,定量分析了薄膜表面粗糙度及微孔洞分布情况,对薄膜在脉冲宽度为10ns,能量分别为50mJ、lOOmJ、200mJ激光辐照下所获得薄膜的表面粗糙度分布情况进行比较分析,结果显示,随着激光功率的增加,多重分形谱的谱宽△a呈增大趋势,且△f为负值,表明ITO.薄膜表面粗糙度增大并形成微孔洞缺陷.     

粗糙薄膜表面的原子力显微镜研究和多重分形分析

用一系列生成元模拟了具有不同特征的、与原子力显微镜图像相似的规则粗糙表面。详细讨论了规则粗糙表面多重分形谱参数的意义。并通过与方均根粗糙度（rms）和简单分形维数D0的比较，描述了多重分形分析的优点。最后用多重分形的方法分析了由AFM测量的ZnO薄膜和高聚物PtBuA薄膜的表面形貌。     

树枝状硫醇分子合成及树枝状硫醇/金组装膜取向液晶能力计算

树枝状硫醇分子可以于金基底上形成基于硫金键的自组装膜,且膜表面可以自组装形成纳米级的条带结构,依据锚定理论预测,此纳米条带形貌在液晶取向领域将具有较大的应用潜力.采用常规的醚化反应对树枝状硫醇分子的制备过程进行了探讨.实验中,分别采用了两种不同的合成方案,实验发现,催化剂和反应条件的不同造成了反应时间和收率的不同.通过方案对比得到了收率高、较易分离的合成路线.对此类组装膜的取向能力进行了计算,并与传统的PI类取向膜进行了对比,结果发现,此类薄膜具有很强的锚定能力.     

Al掺杂ZnO薄膜原子力显微图像的多重分形研究

用原子力显微镜观察溶胶-凝胶法制备Al掺杂znO薄膜的表面形貌,运用多重分形理论研究Al掺杂ZnO薄膜的原子力显微图像,多重分形谱可以很好地定量表征薄膜的表面形貌.结果显示:Al掺杂量为0.5 at.%的ZnO薄膜经550℃退火处理后,rms粗糙度为1.817,Al掺杂量为1.0 at.%的ZnO薄膜经600℃退火处理后,rms粗糙度增大到4.625,相应的分形谱宽△α从0.019增大到0.287,分形参数△f由-0.075变为0.124.     

TiN薄膜表面形貌的分形表征及其演化特征

用反应磁控溅射方法在Si基片上沉积TiN膜,用原子力显微镜(ARM)观察薄膜表面形貌.比较研究了尺码法、盒计数法、功率谱密度法与高度-高度相关函数法计算的表面形貌分形维数Df结果,并研究了TiN膜表面形貌的演化特征.结果表明,功率谱密度法与高度-高度相关函数法计算的Df值与AFM观测尺度不相关,具有较好的稳定性,随着膜厚h增加,薄膜分形维数Df先减小再增加,这是由生长初期基片表面影响与生长后期的晶粒长大所导致的.     

Na掺杂量对ZnO薄膜AFM图像多重分形谱的影响

用溶胶-凝胶法在Si（111）基片上制备Na掺杂ZnO薄膜,利用原子力显微镜（AFM）观察薄膜的表面形貌,采用多重分形理论定量表征薄膜的AFM图像。结果显示：随着Na含量的增加,薄膜平均颗粒尺寸逐渐增大,表面RMS粗糙度从7.4 nm增大到44.4 nm,分形谱宽Δα从0.059增大到0.200,说明薄膜表面高度分布不均匀程度逐渐增大;所有样品的Δf值均大于零,表明薄膜表面沉积于最高峰的原子数多于最低谷的原子数。     

Self‐Assembled Monolayer Coatings on Nanostencils for the Reduction of Materials Adhesion

Nanostencils (shadow masks with submicrometer apertures in a thin silicon nitride membrane) are promising tools for the facile one‐step generation of nanopatterns of various materials by physical vapor deposition. Evaporation through a shadow mask is accompanied by gradual clogging of the apertures due to adhesion of evaporated material. In order to reduce this effect, nanostencils were coated with alkyl and perfluoroalkyl self‐assembled monolayers (SAMs). The formation and properties of SAMs on planar silicon nitride substrates were studied by contact angle goniometry, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The SAMs are stable under evaporation of gold at various angles. SAM‐coated nanostencils showed considerably less adhesion of gold compared to bare Si_xN_y stencils.     

Characterization of defects in flexible circuits with ultrasonic atomic force microscopy

Flexible circuit technology is a key factor in the continued shrinkage of microelectronic components and devices. One of the important applications of the flexible circuits is in hard disk drive industry, where they are used as an interconnection between the preamplifier and head slider assembly of a hard disk drive. At present, defect characterization of flexible circuits is often performed after manufacture usually with optical microscopy. While this may be sufficient for certain low-tech applications, for advanced ultra high-density hard disk components may not be enough. With a continuing reduction of the dimension of the current carrying conductor wires, the size of defects that may affect long-term reliability of the system is reaching the resolution limit of traditional techniques used to characterize the defects. This paper presents combined application of atomic force microscope (AFM) and ultrasonic atomic force microscope (UAFM) to characterize defects in flexible circuits. Three identical flexible circuits from different manufactures are examined using AFM and UAFM. The AFM and UAFM images of a particular region, in the flexible circuit in all the three samples are compared. Images from pure polymer region of the flexible circuit are compared with the images of the regions containing copper and polymer. In general, the UAFM images show subsurface features while AFM images show surface topography. This capability of UAFM can be used to image the grain structure of the copper film without removing the polymer cover layer film. It also detects the sub-micron defects present at the polymer/metal interface. Analysis of the grain structure of copper, distribution of defects at the polymer/metal interface is presented. Based on these observations, the applicability of AFM/UAFM to image the microstructure of copper in flexible circuits and possible effect of defects in flexible circuits on the long-term reliability of the hard disc drive are discussed.     

Formation of Metal Nano‐ and Micropatterns on Self‐Assembled Monolayers by Pulsed Laser Deposition Through Nanostencils and Electroless Deposition

Patterns of noble‐metal structures on top of self‐assembled monolayers (SAMs) on Au and SiO₂ substrates have been prepared following two approaches. The first approach consists of pulsed laser deposition (PLD) of Pt, Pd, Au, or Cu through nano‐ and microstencils. In the second approach, noble‐metal cluster patterns deposited through nano‐ and microstencils are used as catalysts for selective electroless deposition (ELD) of Cu. Cu structures are grown on SAMs on both Au and SiO₂ substrates and are subsequently analyzed using X‐ray photoelectron spectroscopy element mapping, atomic force microscopy, and optical microscopy. The combination of PLD through stencils on SAMs followed by ELD is a new method for the creation of (sub)‐micrometer‐sized metal structures on top of SAMs. This method minimizes the gas‐phase deposition step, which is often responsible for damage to, or electrical shorts through, the SAM.     

Molecular Gelation‐Induced Functional Phase Separation in Polymer Film for Energy Transfer Spectral Conversion

A new strategy for creating the energy transfer spectral conversion thin film by using fluorophore‐functionalized molecular gelation is proposed. This is based on the facts that nanofibrillar phase separation of the self‐assembling pyrene derivative as a fluorophore is formed in a bulk polymer‐containing organic gel, and consequently that the phase‐separated nano domain in a polymer thin film is enough small to keep the transparency but also extremely high Storks shift is gained by efficient excimer formation through highly ordered stacking among the pyrene moieties. When the phase separation‐mediated functional polymer is applied as spectral conversion films (SCFs) for copper–indium–gallium–selenide (CIGS) solar cell, the SCF‐covered solar cell exhibits significant improvement of power conversion efficiency by increase of photocurrent. In this paper, the FRET efficiency and emission wavelength are also demonstrated to be thermotropically switchable since order‐to‐disordered transitions are essential characteristics of as non‐covalent low molecular assembling.     

Electroactive Self‐Assembled Monolayers for Enhanced Efficiency and Stability of Electropolymerized Luminescent Films and Devices

In order to further improve the efficiency and stability of luminescent electrochemical polymerization (EP) films and devices, electroactive self‐assembled monolayers (SAMs) of carbazolyl alkanethiol are successfully designed and applied to modify Au electrode and covalently graft the deposited EP films. The analysis of the formation and coverage of the SAMs by atomic force microscopy (AFM), cyclic voltammetry (CV), and the theoretical calculation provide consistent results indicating the SAM molecules are densely packed and standing upright (liquid‐like) on the Au surface. In addition, ultraviolet photoelectron spectroscopy (UPS), CV, UV, AFM, and sonication treatment reveal that the close‐packed electroactive SAMs are effective at enhancing the work function of electrode, increasing the deposition rate of EP precursor as well as elevating the cross‐linking efficiency and the adhesive property of subsequent EP films. This is a simple and very efficient method for improving the performance of EP device, which has potential applications in display devices.     

Cover Picture: Formation of Metal Nano‐ and Micropatterns on Self‐Assembled Monolayers by Pulsed Laser Deposition Through Nanostencils and Electroless Deposition (Adv. Funct. Mater. 10/2006)

The cover illustrates two‐step fabrication of metal micro‐ and nanostructures on self‐assembled monolayers (SAMs) by pulsed laser deposition and electroless deposition. Metal–SAM–metal junctions are a key component of molecular electronic devices. Pt was deposited in a micropattern by pulsed laser deposition through a stencil. XPS maps show how the Pt pattern is developed into a Cu pattern using electroless deposition as reported by Ravoo, Brugger, Reinhoudt, Blank, and co‐workers on p. 1337. The Cu pattern can also be observed by optical microscopy (background). Patterns of noble‐metal structures on top of self‐assembled monolayers (SAMs) on Au and SiO₂ substrates have been prepared following two approaches. The first approach consists of pulsed laser deposition (PLD) of Pt, Pd, Au, or Cu through nano‐ and microstencils. In the second approach, noble‐metal cluster patterns deposited through nano‐ and microstencils are used as catalysts for selective electroless deposition (ELD) of Cu. Cu structures are grown on SAMs on both Au and SiO₂ substrates and are subsequently analyzed using X‐ray photoelectron spectroscopy element mapping, atomic force microscopy, and optical microscopy. The combination of PLD through stencils on SAMs followed by ELD is a new method for the creation of (sub)‐micrometer‐sized metal structures on top of SAMs. This method minimizes the gas‐phase deposition step, which is often responsible for damage to, or electrical shorts through, the SAM.