Development of a new method of electric/magnetic-filed measurementin a transmission electron microscope

经常使用两种众所周知的方法来观察透射式电子显微镜中的电场/磁场分布。第一种是电子全息术，它需要非常昂贵的场发射枪电子显微镜(FEG TEM)。另一种是Lorentz显微镜，虽然后者可以在常规的透射电子显微镜下进行，但菲涅耳模式下的图像是在散焦条件下获得的，福柯模式下的图像不适合于定量分析。在原位电子全息实验中，我们发现在极低放大模式下的选区衍射(SAD)孔的图像发生了失真，在施加外加静电场的情况下，这种图像发生了失真。对这种现象的几何光学分析表明，图像的失真可以与样品水平上的静电场对电子束的偏转有关。该方法可用于…的观测对常规瞬变显微镜中电场引起的阴影像失真进行了几何电子光学分析，确定了物镜和中间透镜以及聚光镜的场强估算的光学参数。计算了沿电子束通道的静电势分布，并与观测值进行了比较。结果表明，该方法可以定量测量静电场水平部分的积分，并已在一些实际材料中得到应用，例如，在样品位置观察到了半切割的铜网，并在电极上固定了纸箱膜。在有和没有导电碳膜的半圆孔中观察到了局部场分布的差异，从而归一化了孔内的场。网格形孔的阴影像的整体位移对应于试件上部的场强，建议分别检测试件位置和试件上、下部的局域场分布。我们还用我们的方法观察了FEG发射极尖端周围的电场分布。通过我们的研究，在侧面入射保持架上安装电极的几种技术使我们能够在高温下以高分辨率观察陶瓷材料，即CeO_2-ZrO_2陶瓷。作为这项研究的结果，我们所建议的技术发展将使我们能够在不久的将来观察纳米GaP器件的原子机制。较少

Two well known methods are often used to observe the electric/magnetic field distribution in a transmission electron microscope (TEM). The first one is electron holography, which requires a very expensive field-emission gun TEM (FEG TEM). The other one is Lorentz microscopy Though the latter method can be performed in a conventional TEM, the image in the Fresnel mode is obtained in defocused condition and, the image in the Foucault mode is not suitable for quantitative analysis.During in-situ electron holography experiments, we found a distortion of the image of the selected area diffraction (SAD) aperture in the very low magnification mode, celled "Low Mag" mode, while applying an external electrostatic potential to the specimen An analysis using geometrical optics for this phenomenon suggests that the distortion of the image can be correlated to the deflection of the electron beam by the electrostatic field at the level of a specimen. This method can be applied to the observation of … More the electric/magnetic field distribution by a conventional TEM without any additional apparatus.Geometrical electron optics of the shadow image distortion due to electric field in a conventional TEM has been analyzed, and the optical parameters to estimate the field strength have been determined in the system not only for the objective lens and the intermediate lens but also for the condenser lenses. The electrostatic potential distribution has been calculated along the electron beam passage and then compared to the observed value. The result shows that the integral of the horizontal part of electrostatic field can be measured quantitatively.The method we have developed has also been applied in some real materials.For example, a half cut Cu mesh with carton film fixed to the electrode at the specimen position has been observed. The 2D-maps showing the difference of the local field distribution has teen observed in the semicircle holes with and without the conductive carbon film which normalized the field in the hole. The whole shifts of the shadow image of the grid shaped aperture correspond to the field strength upper part of the specimen Separate detection of local field distribution at the specimen position and upper/lower part of the specimen is suggested. The electric field distribution around a FEG-emitter tip has also been observed by using our method.Through our research, several techniques to built the electrodes on to the side entry holder fir the TEM allowed us to observe the ceramics material, i.e., ceria-zirconia ceramics, in a high resolution condition at an elevated temperature. The suggested development of our technique as the results of this research will allow us to observe the atomistic mechanism of the nano-gap devices near future. Less