扫描电镜中荷电现象研究

扫描电镜中荷电现象研究

华佳捷，刘紫微，林初城, 吴 伟^*, 曾 毅

 （中国科学院上海硅酸盐研究所，上海 200050）

摘要：荷电效应是导致扫描电子显微镜(SEM)图像产生缺陷最重要原因之一，它使图像出现异常反差、畸变等现象，严重影响图像质量。镀膜可以有效避免荷电现象，但镀膜不可避免地会一定程度上掩盖样品的真实显微结构。如何在不镀膜的情况下，最大程度减少荷电现象以获得不导电材料真实显微结构特征是材料科学工作者和电镜工作者的共同追求。本文从荷电效应产生的机理出发，阐述了采用合适的加速电压、探测器以及扫描方式等实验参数，对常见的不导电样品，如聚丙烯球、氧化镧粉体、SiO₂球以及羟基磷灰石粉末等样品进行显微结构表征。结果表明若选择合适的实验参数，在不镀膜的情形下可以显著减少荷电甚至使荷电完全消失，从而得到高质量的材料真实显微结构信息。

关键词：扫描电镜；荷电效应；低加速电压；背散射像

中图分类号: TN16；TG115.21⁺5.3；TB383         文献标识码: A

doi：10.3969/j.1000-6281.2014.03.006

Research on chargedphenomenain scanning electron microscope

HUA Jia-jie, LIU Zi-wei, LIN Chu-cheng, WU Wei^*, ZENG Yi

(The State Key Lab of High Performance Ceramics and Superfine Microstructure, Shanghai Insititute of Ceramics, Chinese Academy of Sciences, Shanghai 200050，China)

Abstract:Charge effect is one of the most important factors resulting in image defects for SEM. It seriously influences the imagequality, such as abnormalcontrast, distortion etc.Coating is an usual way to prevent the chargephenomenon, but it is unavoidable to cover the true microstructure of sample. How to minimize thecharge phenomenonand obtain non-conductive materials’ realmicrostructurewithoutcoating is the commonpursuit ofmaterialscientists andelectron microscopytechnicians.In this paper, based on the mechanism of charge effect, we investigated the morphologies of several commonnon-conductivesamplessuch as polypropyleneballs,lanthanumoxide powders, SiO₂ powdersandhydroxyapatitepowdersby appropriatetechnical means, such as acceleration voltage, detectors and scan mode. Chargeeffect will be significantly reduced and even disappears completely if suitable experimental parameters are used, which will result in high-quality material images with true microstructure information.

Keywords: scanning electron microscopy; charge effect; low accelerating voltage; backscatter image

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