Charging of carbon thin films in scanning and phase-plate transmission electron microscopy
Charging of carbon thin films in scanning and phase-plate transmission electron microscopy
复制标题
DOI：
10.1016/j.ultramic.2017.09.009
复制
发表时间：
2018-01-01
期刊：
影响因子：
2.2
通讯作者：
Malac, Marek
中科院分区：
文献类型：
--
作者：
Hettler, Simon;Kano, Emi;Malac, Marek
在透射电子显微镜中对碳薄膜在强电子束辐照下的充电进行了系统的研究，以确定无空穴相板功能的潜在物理基础。研究了不同沉积工艺和单层石墨烯制备的非晶碳薄膜。在中等温度下清洁的薄膜表现出很小的负电荷，而在高温下保持的薄膜是稳定的，不容易产生束流充电。这种电荷是由于化学吸附在薄膜表面的水分子发生了电子刺激脱附(ESD)，并伴随着功函数的变化。电子能量损失谱、无空穴位相板成像、二次电子探测和X射线光电子能谱的实验结果以及对静电势分布的模拟都支持ESD的解释。所描述的基于ESD的模型解释了先前的实验结果，并且对任何与透射式电子显微镜中的相位相关的技术都具有普遍的兴趣。皇冠版权(C)2017由爱思唯尔B.V.出版。保留所有权利。
A systematic study on charging of carbon thin films under intense electron-beam irradiation was performed in a transmission electron microscope to identify the underlying physics for the functionality of hole-free phase plates. Thin amorphous carbon films fabricated by different deposition techniques and single-layer graphene were studied. Clean thin films at moderate temperatures show small negative charging while thin films kept at an elevated temperature are stable and not prone to beam-generated charging. The charging is attributed to electron-stimulated desorption (ESD) of chemisorbed water molecules from the thin-film surfaces and an accompanying change of work function. The ESD interpretation is supported by experimental results obtained by electron-energy loss spectroscopy, hole-free phase plate imaging, secondary electron detection and x-ray photoelectron spectroscopy as well as simulations of the electrostatic potential distribution. The described ESD-based model explains previous experimental findings and is of general interest to any phase-related technique in a transmission electron microscope. Crown Copyright (C) 2017 Published by Elsevier B.V. All rights reserved.