动态化学腐蚀法制备大锥角近场光纤探针

基于液压传递原理,设计出一种用动态化学腐蚀法制备大锥角近场光纤探针的装置.实验结果表明,在传统的化学腐蚀法制备光纤探针的过程中,通过控制腐蚀液液面的上升速度,可以有效地控制探针针尖的形状以及锥角的大小.在此基础上,还论述了分步控制光纤与腐蚀液液面的相对位移的方法在大锥角光纤探针的制备中所具有的独特优越性.利用所制备的大锥角近场光纤探针在扫描近场光学显微镜上对直径为200nm的小球进行探测,其力学像证实该探针具有较高的形貌分辨率(约为50nm). 关键词： 动态化学腐蚀法 大锥角 近场光纤探针     

热拉伸和化学腐蚀相结合制备弯曲光纤探针

提出了原子力/光子扫描隧道显微镜(AF/PSTM)系统的关键部分——双功能弯曲光纤探针的制作方法.采用热拉伸与动态、静态两步化学腐蚀相结合的方法制作出AF/PSTM弯曲光纤探针，弯曲角度约为150°，尖端曲率半径优于100nm，锥角范围为60°—90°.将这种双功能弯曲光纤探针应用在新研制的AF/PSTM系统上，同时获得了样品的光学与形貌图像，实现了图像分解. 关键词： 原子力/光子扫描隧道显微镜 光纤探针 热拉伸 化学腐蚀     

SFM/SNOM结合的扫描探测显微镜

采用光纤探针的扫描近场光学显微镜 (SNOM)存在某些弱点 ,如探针特别脆 ,不易贴近样品表面扫描 ,探针的转输效率低等。近年来发展了将SFM /SNOM结合起来的扫描探测显微镜。利用微加工工艺技术 ,将小孔集成在悬臂探针中 ,使探针既能批量制备 ,又具有很好的重复性。探针悬臂在垂直于样品表面方向上的弹性常数较小 ,针尖不易损坏。在接触模式中利用这种SFM /SNOM组合探针可将样品的形貌像、摩擦力和光学透射像等信息同时记录下来。对于综合研究样品表面的介观性质十分有利。     

制备扫描近场光学显微镜光纤探针的自动化腐蚀方法

提出了一种制备扫描近场光学显微镜光纤探针的自动化腐蚀方案.该方案利用静态腐蚀过程中光纤所形成的特殊结构,及动态腐蚀过程中光纤在氢氟酸中的移动所带来的新月形弯液面在光纤表面接触位置的变化,通过合理控制腐蚀时间来制备尖端锐利、大锥角或多锥体角等各种结构的探针.设计方案采用计算机控制整个装置实现了探针制备过程的自动化,保持了腐蚀光纤探针实验条件的一致性.实验结果表明,采用此方案可以制备出尖端孔径小于100 nm且锥体角高达70°的光纤探针,且重复性高.此外,该方案的装置结构简单,实现容易.     

静动结合的化学腐蚀法制备近场光学探针的理论分析

理论上分析了静动结合的化学腐蚀法制备探针的具体机理及过程。在静态腐蚀的过程中, 利用流体力学Young-Laplace方程的一级近似解获得了光纤插入到HF酸中形成的新月形高度。在动态腐蚀过程中, 详细分析了当静态腐蚀时间和动态腐蚀时间分别取不同值时, 光纤移动速度对光纤探针结构的影响。利用此法可制备出尖端锐利、大锥角或多锥体等各种结构的光纤探针。这为实验上制备出性能优良的探针, 为拓宽扫描近场光学显微镜的应用范围奠定基础。将上述理论分析的结果与本文实验中所得初步结果进行了比较, 所得结果一致。     

虹吸动态化学腐蚀法制备近场光学显微镜光纤探针的研究

基于虹吸原理 ,设计了一种动态化学腐蚀法的简易装置 ,用于制备近场光学显微镜光纤探针。在一般化学腐蚀法的基础上 ,通过改变虹吸管中水的流向和流速来有效地控制探针锥角和锥长 ,制备出多种形貌的光纤探针。与传统的静态化学腐蚀法相比 ,该法具有重复性高、探针形貌可控、操作方便、实验费用低廉、制备的探针表面光滑等优点。利用该装置 ,成功地制备出针尖尺寸 5 0～ 30 0nm ,针尖锥角在 16°～ 6 5°之间可调的光纤探针。同时 ,选择适当的液位差 ,通过一步腐蚀法制备出针尖尺寸小于 5 0nm ,针尖锥角 12 5°的双锥角光纤探针。并对可能的腐蚀机理进行了探讨。     

扫描近场光学显微镜中两类光纤探针传输特性的研究

采用局域模式耦合理论，对扫描近场光学显微镜中的两类光纤探针－腐蚀锥和熔拉锥的传输特性进行了比较和分析。给出了光在探针锥中传输时耦合效率的分布情况，以及传输效率随锥长，针尖直径和光波长变化的特性。     

用时阈有限差分方法研究光纤微探针近场分布特性

采用三维时间域有限差分（FDTD）方法研究了扫描近场光学显微镜中光纤微探针的近场分布特性,研究结果表明,锥形裸光纤探针的近场光中,以从探针锥变区侧面泄露的光即传播场为主,当在探针的侧面镀上一层金属膜对于从侧面泄露的光具有较好屏蔽效果,因而比裸光纤探针具有更好的空间束缚能力,无论是裸光纤探针还是金属膜探针,入射偏振光从针尖出射手发生了退极化现象,近场分布中产生与入射光偏振方向垂直的其它两个电场分量,而且金属膜探针的退极化分量对近场分布的影响比裸探针显著得多,如果在近场成像中接收退极化分量而不是总场则可以提高近场成像的对比度,还详细地分析了微探针的近场分布特征与退极化之间的关系。     

一种高透过率光纤探针的制作

本文介绍了一种用于近场扫描光学显微镜(NSOM)中的高透过率光纤探针的制作方法。采用缓冲氢氟酸腐蚀低掺杂的普通单模石英光纤,选取适当比例的腐蚀液,可以得到直径、圆锥角均十分理想的针尖。这种方法不需要高掺杂的特殊光纤或是采用先熔拉后腐蚀的复合工艺。针尖经过镀膜后经测量为针尖直径100nm、透过率5.5×10^-4.     

高效、高分辨光纤微探针的制备及检验

提出两种同时满足高分辨、高传光效率的探针模型以及制备方法 :先用自制热拉装置将光纤拉制成过渡区为双曲线或抛物线形的探针 ,然后用 4 0 %氢氟酸进行快速腐蚀 ,使探针孔径变小而保持过渡区域形状和锥度基本不变。所获探针孔径变化范围为 2 0～ 2 0 0 nm,锥度 2 0°～ 6 0°。为检验探针性能 ,将两种探针的出射光分布与用传统热拉法所得到探针进行对比 ;探测了光子扫描隧道显微镜状态下的倏逝波衰减曲线 ;给出了用集光式扫描近场光学显微镜得到的近场光学图像 ;同时 ,验证了探针对剪切力控制的适用性。     

The coaxial tip as a nano-antenna for scanning near-field microwave transmission microscopy

A novel scanning-probe setup is reported that maps the complex transmission of microwaves. Response to topographic features as small as 15 nm was observed. The sharpened coaxial probe tip serves as a microwave antenna and, at the same time, as a tunnel tip to warrant precise distance control by STM (scanning tunneling microscope) feedback. The instrument can be applied to map the microwave conductivity of, e.g. thin films or low-dimensional semiconductors. Consequences for the development of an infrared microscope are outlined.     

微结构对Eu掺杂Bi4Ti3O12铁电薄膜铁电性能的影响

采用金属有机物分解法在Pt/Ti/Si(111)基底上制备了退火温度分别为600℃,650℃,700℃的Bi_3.15Eu_0.85Ti₃O₁₂(BET)铁电薄膜,并对其结构及铁电性能进行了测试,再使用扫描探针显微镜对BET薄膜的电畴翻转进行了实时观测.BET薄膜c畴发生180°畴变的最小电压为+6V,而r畴由于其高四方性,即使极化电压增至+12V也不会发生翻转.薄膜的铁电性主要源于c畴的极化,随着退火温度的升高,c畴的区域面积增加,BET薄膜的剩余极化强度随之增大.退火温度为700℃的BET薄膜剩余极化强度达到84μC/cm². 关键词： 铁电薄膜 电畴翻转 扫描探针显微镜     

Scanning probe microscope with interchangeable AFM-FFM and STM heads

Summary A scanning probe microscope operating in air with interchangeable atomic force-friction force (AFM-FFM) and electronic-tunnelling (STM) heads is presented. Our AFM operates in the so-called contact mode and utilizes the optical-lever detection method which allows simultaneous measurement of the topography as well as the lateral force. The set-up also contains an optical microscope to control both the sample and the probe laser spot on the cantilever. The experimental method to change from AFM to STM operation is based on the use of the probe laser beam and the optical microscope. The maximum scanning area is (24×24) μm² and it is well embraced in the optical-microscope visual field. The microscope attains atomic resolution in air in both AFM and STM configuration. Its performance is demonstrated on the surface of different samples. In honour of Prof. Fausto Fumi on the occasion of his retirement from teaching.     

Electrical Scanning Probe Microscopy: Investigating the Inner Workings of Electronic and Optoelectronic Devices

Semiconductor electronic and optoelectronic devices such as transistors, lasers, modulators, and detectors are critical to the contemporary computing and communications infrastructure. These devices have been optimized for efficiency in power consumption and speed of response. There are gaps in the detailed understanding of the internal operation of these devices. Experimental electrical and optical methods have allowed comprehensive elaboration of input–output characteristics, but do not give spatially resolved information about currents, carriers, and potentials on the nanometer scale relevant to quantum heterostructure device operation. In response, electrical scanning probe techniques have been developed and deployed to observe experimentally, with nanometric spatial resolution, two-dimensional profiles of the electrical resistance, capacitance, potential, and free carrier distribution, within actively driven devices. Experimental configurations for the most prevalent electrical probing techniques based on atomic force microscopy are illustrated with considerations for practical implementation. Interpretation of the measured quantities are presented and calibrated, demonstrating that internal quantities of device operation can be uncovered. Several application areas are examined: spreading resistance and capacitance characterization of free carriers in III-V device structures; acquisition of electric potential and field distributions of semiconductor lasers, nanocrystals, and thin films; scanning voltage analysis on diode lasers—the direct observation of the internal manifestations of current blocking breakdown in a buried heterostructure laser, the effect of current spreading inside actively biased ridge waveguide lasers, anomalously high series resistance encountered in ridge lasers—as well as in CMOS transistors; and free-carrier measurement of working lasers with scanning differential spreading techniques. Applications to emerging fields of nanotechnology and nanoelectronics are suggested.     

外加电场对铁电薄膜相变的影响

采用热力学非线性理论,研究了外加电场对立方基底Pb(Zr_0.3Ti_0.7)O₃(PZT)铁电薄膜相变的影响.通过数值计算,得到了"失配应变-外加电场"相图,及外加电场与极化强度的关系.当外加电场达到186 kV/cm时,能使生长在SrTiO₃ 基底上PZT铁电薄膜从单斜r相转变为c相.在实验上,采用扫描探针显微镜通过对PZT薄膜施加不同的极化电场来研究了它的电畴翻转.从得到的压电响应相图可以看出,绝大多数的电畴是清晰可 关键词： 铁电薄膜 相变 扫描探针显微镜 失配应变     

Direct observation of the potential distribution within organic light emitting diodes under operation

We show the first direct measurement of the potential distribution within organic light emitting diodes (OLEDs) under operation and hereby confirm existing hypotheses about charge transport and accumulation in the layer stack. Using a focused ion beam to mill holes in the diodes we gain access to the cross section of the devices and explore the spatially resolved potential distribution in situ by scanning Kelvin probe microscopy under different bias conditions. In bilayer OLEDs consisting of tris(hydroxyquinolinato) aluminum (Alq₃)/N, N ′‐bis(naphthalene‐1‐yl)‐N,N ′‐bis(phenyl) benzidine (NPB) the potential exclusively drops across the Alq₃ layer for applied bias between onset voltage and a given transition voltage. These findings are consistent with previously performed capacitance–voltage measurements. The behavior can be attributed to charge accumulation at the interface between the different organic materials. Furthermore, we show the potential distribution of devices with different cathode structures and degraded devices to identify the cathode interface as main culprit for decreased performance. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)