Electron holography of thin amorphous carbon films: Measurement of the mean inner potential and a thickness-independent phase shift

被引:31
作者
Wanner, M
Bach, D
Gerthsen, D [1 ]
Werner, R
Tesche, B
机构
[1] Univ Karlsruhe, Lab Elektronenmikroskopie, Karlsruhe, Germany
[2] Univ Karlsruhe, Inst Theorie Kondensierten Mat, D-76128 Karlsruhe, Germany
[3] Max Planck Inst Kohlenforsch, D-45470 Mulheim, Germany
关键词
transmission electron microscopy; electron holography; mean inner coulomb potential; surface potential; amorphous carbon; electron energy-loss spectroscopy;
D O I
10.1016/j.ultramic.2005.10.004
中图分类号
TH742 [显微镜];
学科分类号
摘要
The phase shift induced by thin amorphous carbon films with thicknesses between 1 and 16 nm was measured by electron holography in a transmission electron microscope. Large phase shifts Delta phi are observed as the thickness of the amorphous C films decreases which cannot be described by the well-known equation Delta phi = C-E V(0)t (V-0: mean inner Coulomb potential of the material. t: sample thickness). Data plotted in a Delta phi vs. t diagram can be well-fitted by a modified equation Delta phi = C-E V(0)t + phi(add). The mean inner Coulomb potential of the amorphous carbon with a density of 1.75 g/cm(3) was determined to be 9.09 V which is consistent with previous experimental data for amorphous carbon with a higher density. The thickness-independent phase Offset phi(add) of 0.497 rad is large for amorphous carbon under the given experimental conditions. We suggest that a surface-related electrostatic potential is responsible for the thickness-independent contribution phi(add). (c) 2005 Elsevier B.V. All rights reserved.
引用
收藏
页码:341 / 345
页数:5
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