基于改进型DLIA的AFM探针高速振幅检测

轻敲模式是原子力显微镜(AFM)最为常见的扫描模式之一。轻敲模式以探针振动信号幅值作为反馈信号,实行实时检测。目前,有模拟检测和数字检测两种检测方法,模拟检测方法由于模拟器件固有的温漂导致误差较大,数字检测方法误差小但运算量较大。提出了一种实时检测轻敲模式信号振幅的改进型数字锁相放大器(MDLIA),在自制的AFM扫描成像系统中同时具备误差较小和运算量较小两个优点。MDLIA使用与振动信号同频同相的方波信号作为参考信号,因此仅采用单通道运算即可检测振动信号幅值。首先通过理论分析介绍了MDLIA的原理,然后介绍各组成部分及实现过程,最后通过运算耗时实验验证MDLIA运算量小且运算速度快的特点,并通过误差对比实验证明MDLIA误差较小,同时通过标准栅格扫描实验验证MDLIA的稳定性。     

纳米颗粒填充的PTFE微结构的原子力显微镜测量

本文报道了用原子力显微镜(AFM)研究多种纳米微粒填充的聚四氟乙烯(PTFE)材料的结构组成,观察了在纳米颗粒填充的PTFE中,纳米微粒的分散不均匀性以及纳米粉末在与PTFE混合、压制后发生的团聚现象。     

小鼠胚胎干细胞超薄切片的AFM观察

对Balb／c小鼠胚胎干(ES)细胞的超薄切片进行AFM成像,以获得ES细胞内部结构的信息。尝试把AFM作为ES细胞形态学鉴定的一种手段。方法：利用超薄切片技术,将ES细胞样品制成厚约60nm的切片,固定在盖玻片上,用AFM在大气中观察。结果：观察到不同时期的单个ES细胞以及分裂时期ES细胞核中高度盘曲和浓聚的染色体。利用AFM的高分辨成像能力,观察了线粒体亚显微结构,细胞基质和核质的超微结构。     

兔骨骼肌ryanodine受体/钙释放通道的AFM研究

Ryanodine受体（RyR)是位于细胞内质网膜上的钙释放通道,在肌细胞的兴奋－收缩偶联中发挥重要作用。RyR难于结晶,以往主要是用电镜和计算机三维重组相结合的方法来获得其高级结构的信息。由于RyR结构庞大,易于水解,在提取的过程中需要加入外源性磷脂以保护其结构,而磷脂的存在对电镜的分辨率有影响,所以电镜研究的RyR在提 过程中一般不添加外源性磷脂,这样得到的结构信息并没有反映RyR在生理状况下的真实情况,我们用原子力显微镜（AFM）对RyR进行研究,经过了空气中RyR成像,液体中RyR成像,重组到脂双层中的RyR研究几个阶段,提供了RyR在接近生理条件下的结构信息,并为进一步研究其结构和功能的关系打下了基础。     

微加工硅表面基于AFM的纳米压痕测量与分析

原子力显微镜(AFM)在完成对单晶硅的微加工后，其金刚石针尖被用做一个纳米压痕头以实现微加工区域内外机械性质的测量与分析。结果表明，以安装有金刚石针尖的AFM在经过化学机械抛光的硅基片上所进行的微加工，即使使用极小的切削力也会在加工表面形成变质层，但是其厚度值要小于化学机械抛光的硅表面变质层。由AFM测量的纳米级硬度值要大于由传统的Vickers和Hysitron硬度测试仪所测量的值。另外，随着AFM压入载荷的减小，纳米级硬度值呈现出增加的趋势，这是由于在很小的压入载荷下所呈现出的压痕尺寸效应所导致。     

面向可控自组装的DNA纳米管可编程AFM操作北大核心

"核心"DNA纳米结构的精确定位是实现指定位置的DNA纳米结构可控自组装构建纳米器件或系统的关键难题之一。研究了一种可编程控制的原子力显微镜(AFM)操作方法,通过运用操作过程中参数调控,实现液体环境中柔性DNA纳米结构的可控定位及定向操作。对操作振幅和溶液中Mg2+浓度两个关键参数进行了实验优化。实验采用的是长400 nm和直径约6 nm的DNA纳米管状结构。实验结果表明,在操作振幅为3.5 nm和Mg2+浓度为10 mmol/L的优化控制条件下,应用可编程控制的AFM调控操作方法,实现了液体环境中DNA纳米结构的定位定向操作,且成功率达到80%。     

液相型AFM的研制与金属腐蚀原位研究

介绍了新型液相型原子力显微镜（AFM）的工作原理、系统结构和独特性能,讨论了该AFM在金属腐蚀研究中的应用。利用液相型AFM对碳钢在NaCl溶液及Pb在草酸溶液中的腐蚀过程进行了原位观察,获得了理想的扫描图像。实验结果表明,金属腐蚀最初起始于原子或纳米尺度,之后逐渐扩大到宏观尺度;金属表面的凹坑或缺陷可加速其腐蚀;而表面突起的结构则被一层层腐蚀。     

原子力显微镜磁驱动轻敲模式在活细胞成像中的应用研究

应用MI公司最新发展的磁驱动轻敲模式(MAC mode)时体外培养成纤维细胞系3T3细胞进行在位成像研究.分别用力常数为0.95 N/m及0.03 N/m的微悬臂进行磁驱动轻敲模式成像,并与接触模式进行比较.同时研究了固定细胞与活体细胞之间的形貌差异.结果显示,利用上述两种微悬臂探针,磁驱动轻敲模式均可获得高分辨像.与接触模式相比,磁驱动轻敲模式对活细胞的影响较小,在细胞膜表面微结构及细胞内亚结构成像方面,有明显优势.而接触模式由于其施力方式,使活细胞应力纤维应激性绷紧,更适合于对活体细胞应力纤维的成像研究.固定细胞与活细胞表面形貌存在较大差异,在生理环境下,进行活细胞检测更能了解细胞的真实状况.     

基于AFM的微纳米结构力学特性测量

原子力显微镜（ＡＦＭ）以其优异的特性不仅在微米、纳米的范围内获取图象。同时可以获取针尖与样品之间的作用力,为研究样品的力学性能提供了新思路。对ＡＦＭ在力学测量上的原理和应用进行了综述,并提出基于ＡＦＭ的生物样品的力学测量的新方法。     

纳米材料的几种扫描探针显微表征方法

扫描探针显微镜（SPM）作为一种广泛应用的表面表征工具,不仅可以表征三维形貌,还能定量地研究表面的粗糙度、孔径大小和分布及颗粒尺寸,在许多学科均可发挥作用.以纳米材料为主要研究对象,综述了国外最新的几种扫描探针显微表征技术,包括扫描隧道显微镜（STM）、原子力显微镜（AFM）和近场扫描光学显微镜（SNOM）等方法,展示了这几种技术在纳米材料的结构和性能方面的应用.     

Silicon and Nanoscale Metal Interface Characterization Using Stress-Engineered Superlayer Test Methods

Thin film layers are utilized in emerging microelectronics, optoelectronics, and microelectromechanical systems (MEMS) devices. Typically, these thin film layers are composed of different materials with dissimilar properties. A common mode of failure for thin films is delamination caused by external loading or intrinsic stress present in the materials. To characterize bonded thin film material systems, it is necessary to measure the interfacial fracture toughness. When material thicknesses approach micro- and nanoscales, interfacial fracture toughness measurement is a challenging task. Accordingly, innovative test techniques need to be developed to study interfacial fracture parameters. The ongoing research at Georgia Institute of Technology is developing fixtureless delamination test techniques that can be used to measure interfacial properties of micro- and nanoscale thin films. The single substrate decohesion test (SSuDT) and the single-strip decohesion Test (SSDT) are such fixtureless tests under development. In these tests, a thin film interface material of interest is deposited on a substrate. Then, delamination is driven by a superlayer material on top of the interface material. This superlayer material is sputter deposited and has high intrinsic stress. A deposited release layer material allows for the contact area between the interface material and the substrate to be controlled. These tests differ in geometry, but share the same generic methodology and can be used for a number of material systems over a wide range of mode mixities. This paper presents the methodology and implementation of the SSuDT and SSDT tests and compares results to better understand their scope. A case study of the interfacial fracture toughness as a function of mode mixity for titanium and silicon interface was performed.      

一种评估旋转式机械设备工况的方法

用数据采集系统采集旋转式机械设备旋转构件上所选测点的振动位移，并计算出该振动参数基本统计特性的数值，就可以应用本文提出的判断不等式对设备的工况进行初步评估。动力增益因子的引入使静态测量精度能用于对振动动态过程的分析。以集成电路制造专用设备硅片磨床为例，阐述了这种评估方法。     

Spheroidal Mode Approach for the Characterization of Metallic Objects Using Electromagnetic Induction

We propose a spheroidal mode approach to characterize the electromagnetic induction (EMI) response of buried objects, assumed to be much more conductive than their environment. Both the excitation and the response are formulated as the linear superpositions of basic spheroidal modes. The scattering coefficients characterize objects, regardless of their geometrical complexity and material inhomogeneity, due to the orthogonality of the spheroidal modes. The ill-conditioning encountered in retrieving the scattering coefficients is dealt with by mode truncation and Tikhonov regularization. The approach is tested for both simulated and measured data, and the retrieval results show encouragingly that only few excitation and response modes effectively represent the EMI response of the objects. The proposed approach is therefore promising in the detection and classification of buried objects     

Nanoscale electrical characterization of ultrathin high-k dielectric MOS stacks: A conducting AFM study

Extreme scaling in both silicon and alternative channel CMOS has highlighted the importance of localized characterization on the nanometer scale. We have used a conductive-contact atomic force microscopy (C-AFM) technique in ultra high vacuum (UHV) conditions to analyze and compare intrinsic stack degradation mechanisms leading to breakdown (BD) for ultrathin high-k dielectric films of (4 nm) Hf_xSiO_y/SiO₂ on Si and (2 nm) ZrO₂/GeO₂ on Ge. Simultaneous nanoscale current–voltage I–V characteristics, topography, tunneling current and relative tip–surface contact interactions as normal and lateral force maps revealed localized injected charge dependence on electrical stress. It is shown that the charge can propagate laterally. Successive voltage scanning is related to the overall post-BD conductivity for pre- to post-BD degradation propagation. In contrast with SiO₂ interface, an increased GeO₂ interlayer reactivity yielding more active interface defects is suggested.     

Methods of Multiplex Spectroscopy in the Characterization of Nanoscale Multilayers

The concept and mathematical framework are presented of a multiwavelength approach to optical reflectometry, including ellipsometry, in order to obtain a nondestructive tool for the analysis and depth profiling of ultrathin inhomogeneous films. It is noted that the multiwavelength approach allows one to employ ideas of multiplex spectroscopy and computerized tomography, the film being characterized by solving an integral equation of the first kind. Some applications of the approach are discussed, including measurement of complex-permittivity and chemical-composition profiles of oxide films on metal substrates.     

AFM Characterization of Raman Laser-Induced Damage on CdZnTe Crystal Surfaces

Raman laser studies of detector-grade CdZnTe crystals show an increase in intensity of the Te peaks of the Raman spectra even at very low laser powers. In this study, atomic force microscopy (AFM) was used to characterize the extent of damage to the CdZnTe crystal surface following exposure to the Raman laser. AFM images revealed localized surface damage in the areas exposed to the Raman laser beam. Additional studies using conductive-probe AFM techniques provided localized electrical information for the laser-induced Te-rich areas.     

Investigation of Switching-Time Variations for Nanoscale MOSFETs Using the Effective-Drive-Current Approach

This letter investigates the impacts of random dopant fluctuation (RDF) and line edge roughness (LER) on the switching-time (ST) variation for nanoscale MOSFETs using the effective-drive-current $(I_{rm eff})$ approach that decouples the ST variation into transition-charge $(Delta Q)$ and $I_{rm eff}$ variations. Although the RDF has been recognized as the main variation source to the threshold-voltage variation, this letter indicates that the relative importance of LER increases as the ST variation is considered.      

压电泵振动模态的有限元分析

采用有限元法，利用ANSYS软件，通过建模、划分网格、加载和求解等途径，计算出压电射流角速度传感器压电泵的前3阶振动模态。结果表明，采用基频作为工作频率最理想．与实测值比较，有限元法计算值相对误差小于6．1％，优于能量法计算值。该方法为压电射流角速度传感器压电泵的优化设计提供了重要的依据。     

矩形板压电振子振动有限元分析

利用有限元法，对具有四个凸起的矩形板压电振子的振动状态进行了解析计算，并根据其振动特点，重新选择结构参数制作了超声矩形板马达，结果大大提高了这种马达的转速和效率等性能。     

Liq/ITO结构表面与界面的AFM和XPS研究

采用真空蒸发沉积的方法,在覆盖有ITO膜的玻璃基片上沉积一层Liq.利用原子力显微镜(AFM)对制备的Liq/ITO样品表面进行扫描,发现Liq粉末表现为岛状形态,其表面极不平整,存在大量裂缝和空隙,有许多针孔.用X射线光电子能谱(XPS)研究了Liq/ITO紧密接触的表面和界面电子状态.对样品In3d和Sn3d的电子状态分析也证实了ITO表面沉积Liq膜存在裂缝和针孔,这些裂缝和针孔吸附了空气中大量的气体分子;对C1s谱的分析发现,ITO膜表面存在一定的C污染;对N1s谱分析可知,界面处N原子与O、In和Sn原子有相互作用,这将会影响Liq的发光颜色.