碳纳米管原子力显微镜针尖的研究

本文研究了制作碳纳米管原子力显微镜针尖的方法和过程。在光学显微镜下，通过两个微工作台操纵将纯化后的多壁碳纳米管粘结在传统的原子力显微镜的Si针尖上。运用电蚀的方法优化碳管针尖的长度使其达到高分辨率的要求。我们运用制作的碳纳米管针尖在敲击模式下时G型免疫球蛋白进行扫描成像，结果显示了其典型的Y形结构，这是传统AFM的Si针尖无法获得的。     

Cross-sectional electrostatic force microscopy of semiconductor laser diodes

The possibilities of electrostatic force microscopy in studying semiconductor device structures are considered. A study of the cross sections of a GaAlAs/GaAs laser diode demonstrated that the method yields the position and width of the n-p junction in the laser structure, the profile of the voltage drop across the layers constituting the structure, and the distribution of injected carriers in the waveguide.     

电场力显微镜不同探针对表面电荷注入的影响

在电场力显微镜(EFM)下利用不同金属镀层微探针,在微纳米尺度下对聚酰亚胺薄膜的表面电荷生成特性进行研究。采用电场力显微镜导电探针在聚酰亚胺薄膜表面注入电荷,并对微纳米区域产生的电荷进行表征,结果表明不同金属镀层的微探针对聚酰亚胺薄膜上电荷注入效果不同。铂铱合金镀层具有比钴铬合金镀层更高的功函数fm,因此前者在金属-电介质接触中产生更大肖特基势垒,进而降低了电荷的注入程度。该研究为微纳米尺度下探索聚合物绝缘材料表面电荷生成、发展机理提供了一个新的研究方法和途径。     

Study of the potential distribution in a forward-biased silicon diode using electrostatic force microscopy

Electrostatic force microscopy was used to study the potential distribution in a forward-biased epitaxial-diffused n ⁺-n-p-p ⁺ silicon diode. Distributions of potential and capacitance were determined across the cleaved surface, which intersected the layers in the diode structure. Variations in the surface potential and capacitance were preliminarily measured with a submicrometer spatial resolution and were used to determine the position and width of the n-p junction; the distribution of applied forward bias in the diode was also assessed. It is shown that an additional potential barrier for injected charge carriers may exist in the vicinity of the n ⁺-n junction in the diode under consideration. For an injection-current density exceeding 100 mA/cm², the voltage drop across this barrier becomes comparable with the voltage variations across the operating n-p junction.     

GPS系统在长途干线光缆设计中的应用

随着科技的发展,GPS系统在各个领域已经得到了越来越广泛的应用。本文阐述GPS系统的基本原理,并着重介绍了GPS系统在长途干线光缆工程中的应用,与传统勘察设计方法的比较,并总结出GPS系统应用在干线光缆勘察设计中的优势。     

nRF401无线收发芯片的长距离通信设计

nRF401系列高速单片无线收发芯片为短距离无线数传应用提供了较好的解决办法,在某些应用中需要尽可能长的通信距离,本文探讨影响nRF401通信距离的因素并提出设计的方法.     

长距离光传输技术的应用和系统设计

１引言在一些地方，广播电视发射台和有线电视台往往建在离电台、电视台播控中心较远的地方，需要考虑如何将广播、电视信号以适当的方式，较小的失真，以及合理的造价传送至发射台和有线台。在建设城阳广播电视信号传输系统时，考虑到既要保证传输质量，又能减少设备造价...     

Detection of nanoscale etch and ash damage to nanoporous methyl silsesquioxane using electrostatic force microscopy

We have used electrostatic force microscopy (EFM) to detect nanoscale dielectric constant variations resulting from damascene processing of blanket and patterned films of nanoporous methyl silsesquioxane (MSQ) (k = 2.2). Ash processing can cause significant degradation of the dielectric constant for both blanket and patterned MSQ films if the film is exposed to moisture. We have observed that this degradation is reversible because the apparent dielectric constant of the ashed film is nearly the same as the as-deposited film if the film is baked at 80-150 °C. Reactive ion etching (RIE) causes ∼100 nm deep side wall damage in patterned samples as well as leaving a redeposited layer that has a higher dielectric constant. We also present some initial results that show the strength of the EFM signal is humidity dependent.     

Model-based feedback controller design for dual actuated atomic force microscopy

In atomic force microscopy (AFM) the imaging speed is strongly limited by the bandwidth of the feedback loop that controls the interaction force between the measurement tip and the sample. A significant increase in closed-loop bandwidth without sacrificing positioning range can be achieved by combining a long-range, low-bandwidth actuator with a short-range, high-bandwidth actuator, forming a dual actuated system. This contribution discusses the design of a model-based feedback controller that controls the tip-sample force in dual actuated AFM. Special emphasis is given on guaranteeing robust stability of the feedback loop under influence of variations in the dynamical behavior of the system, and to prevent strong destructive interference between both actuators. To prevent instability of the feedback loop due to saturation of the short-range actuator, an anti-windup controller is presented that robustly stabilizes the system under all imaging conditions. The designed feedback controller is implemented on a prototype dual actuated AFM system, and demonstrates a disturbance rejection bandwidth of 20 kHz, which is about 20 times faster than the model-based controlled single actuated system. AFM images are obtained verifying a significant reduction of force variations between the tip and the sample while imaging. The faster control of the tip-sample force reduces the residual tracking error and, thus, reduces the chance of damage or wear of the tip and the sample, and allows for faster imaging.     

基于隧道电流检测方式的原子力显微镜纳米检测系统设计

原子力显微镜（AFM）是当前进行材料表面微观形貌观察及分析的强有力工具之一。本文主要介绍一种隧道显微镜（STM）检测方式的原子力显微镜纳米检测系统（AFM.IPC-208B）,该AFM系统设计是在STM.IPC-205B系统设计的基础上,采用隧道电流工作方式,将STM与AFM功能组合兼容。文章详细阐述了AFM.IPC-208B系统的设计原理、镜体、扫描控制以及数据采集。新设计的AFM.IPC-208B系统仍具有0.1nm的分辨率,检测范围为0～2mm×2mm,系统操作简易,工作效率高,与原STM.IPC-205B系统兼容,工作性能稳定可靠。     

用于扫描近场光学显微镜的一种新型非光学样品-探针间距测控方法

扫描近场光学显微镜ＳＮＯＭ自八十年代中期以来获得了的发展,并具有超衍射极限光学分辨率。作为ＳＮＯＭ的关键技术之一,样品与探针间距的控制十分重要而且实现起来比较困难。基于剪切力原理,本文提出了一种新型的样品－针尖间距测控的非光学方法,邓,利用压电陶瓷的压坟电效应,将压电陶瓷分为三部分,分别用地激励探针法动,固定地以及擦在振动变化。该方法的灵敏度很高,可将样吕－针尖的间距控制在３ｎｍ左右,而且廉价,制     

静电拉伸薄膜反射镜的面形分析

静电拉伸薄膜反射镜属于一种空间新概念超轻反射镜。成形控制是其关键技术,而面形分析是成形控制的基础。基于Karman方程分析了薄膜反射镜在均匀载荷作用下的面形,并推导了抛物面面形所需的非均匀载荷;对Ф300 mm口径薄膜反射镜进行了有限元建模,针对不同载荷作用下的薄膜拉伸面形进行了光机集成分析,反射镜中心挠度与理论计算吻合,反射镜在非均匀连续载荷作用下的波前差相对于均匀载荷作用降低了一个数量级,非均匀离散载荷下的面形也得到了改善。结果表明:薄膜反射镜在非均匀载荷下可以有效抑制像差并能控制薄膜成形。基于仿真结果设计了半解析薄膜反射镜成形控制的方法,为薄膜反射镜的成形控制提供了技术基础。     

Wave-division multiplexing in the Sprint long distance network

The deployment of wave-division multiplexing (WDM) systems in the long distance network has dramatically increased the usable bandwidth of the embedded fiber optic cable. This article documents the utilization of WDM equipment in the Sprint long distance network. Many of the factors affecting the deployment of WDM systems are discussed from the selection and installation of the fiber optic cable in the 1980s to the current bandwidth demand. The future of WDM systems, network architecture, and the emerging optical layer are briefly addressed     

高速原子力显微术研究进展

自1986年发明原子力显微镜以来,它已成为材料、生物以及纳米科技等许多领域的重要工具。由于常规原子力显微镜成像速度缓慢,在动态过程观测、工业生产线原位测量以及高密度信息存储等领域的应用受到限制,因此发展高速原子力显微术近年来已引起国内外的高度关注。本文综述了高速原子力显微术关键技术(包括:微小探针、高速扫描器设计和控制方法)以及应用等方面的最近进展。     

On the reliability of scanning probe based electrostatic force measurements

The dimensions of semiconductor devices rapidly decreasing, the detection and control of spatial inhomogeneities of material properties on a sub-μm scale becomes essential.For mapping various electrical properties with nearly nm-resolution, scanning probe techniques appear to be ideally suited. However, data evaluation always involves a transfer from measured to real properties by a device depending convolution procedure.We report on our results for different modes of electrical measurements, namely scanning Kelvin probe microscopy (SKM) and scanning capacitance microscopy (SCM) on various sample systems discussing the influence of experimental parameters. In addition, results of finite element simulations on this topic are presented.It turns out that the averaging function correlating real and measured data may appear quite simple, thus making a reliable reconstruction possible. On the other hand, the existence of surface charges can drastically change the results.     

Control of interaction force in constant-height contact mode atomic force microscopy

Contact mode is a versatile and widely used technique for imaging samples using the Atomic Force Microscope (AFM). When contact mode imaging is performed in constant-height mode, it enables linear and faster response but leads to uncontrolled tip-sample forces. Here, a control strategy based on magnetic actuation is proposed to achieve high-bandwidth control of the tip-sample forces in constant-height contact mode AFM. A magnetic particle attached to the AFM probe is actuated by an external solenoid and employed for force regulation. A quasi-static model has been proposed and employed to develop the control strategy. Likewise, the contact natural-frequency, which decides the limit of achievable speed, has been shown to be significantly higher relative to the free probe and to be relatively insensitive to the particle size. Subsequently, a setup is developed to validate the control strategy and demonstrate reduction of tip-sample force variation by over a factor of 12 compared to conventional constant-height mode operation. Likewise, in comparison with conventional contact mode AFM, an improvement of linearity by over a factor of 9 and improvement in response speed by a factor of 100 have been demonstrated while imaging hard samples. The system has been shown to image topography at speeds of 2.44 frames per second while regulating the interaction force. Finally, the stiffness of a sample has also been characterized using the developed system and simultaneous estimation of topography has also been demonstrated. They are shown to agree well with theoretical expectations.     

FPGA在远程激光测距中的应用

介绍了利用ALTERA公司的FPGA芯片(EP1C3T144I7)及其配置芯片(EPCS1SI8)进行激光测距机设计的一种实现方法。对于系统硬件的工作流程和软件的设计给予了描述,最后给出了外场实验的测试数据。试验数据表明,该系统达到了良好的效果。该系统具有体积小、功耗低、工作稳定、性能优越、可在线重复编程、升级能力强的特点。     

Applications of scanning electrical force microscopy

The capabilities of Scanning Electrical Force Microscopy (SEFM) based on non-contact AFM (atomic force microscopy) concerning the characterization of microelectronic structures of silicon are presented. Surface potential differences due to carrier generation and capacitance differences due to oxide layers are discussed at examples of lateral and cross-sectional images of a resistance and a MOS-structure.     

AFM反馈系统仿真模型的建立及实验

原子力显微镜（ AFM）广泛应用于纳米尺度的成像和操纵,其较低的扫描速度严重影响了测试的效率。为此,许多研究人员通过设计先进的Z向控制算法改善系统的响应速度,达到提高扫描速度的目的,而先进的控制算法的实现首先需要对AFM的Z向反馈系统进行建模。为此,本文提出一种简单准确的系统辨识方法,通过对系统输入输出数据的分析,得到AFM的Z向反馈系统模型,并利用该模型验证先进控制算法的控制性能。实验表明该方法能为先进控制算法的设计和实现建立有效的仿真模型。     

AD420在远程控制系统中的应用

本文详细介绍了ＡＤ４２０在远程配料控制系统中的应用,给出了远程配料控制系统的硬件设计和软件设计。