Mapping of valence energy losses via energy-filtered annular dark-field scanning transmission electron microscopy

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• 作者：Lin Gu ; Wilfried Sigle ; Christoph T. Koch ; Jaysen Nelayah ; Vesna Srot ; Peter A. van Aken
• 关键词：EFTEM ; EF-STEM ; EELS ; Band-gap
• 刊名：Ultramicroscopy
• 出版年：2009
• 出版时间：August 2009
• 年：2009
• 卷：109
• 期：9
• 页码：1164-1170
• 全文大小：740 K

文摘

The advent of electron monochromators has opened new perspectives on electron energy-loss spectroscopy at low energy losses, including phenomena such as surface plasmon resonances or electron transitions from the valence to the conduction band. In this paper, we report first results making use of the combination of an energy filter and a post-filter annular dark-field detector. This instrumental design allows us to obtain energy-filtered (i.e. inelastic) annular dark-field images in scanning transmission electron microscopy of the 2-dimensional semiconductor band-gap distribution of a GaN/Al₄₅Ga₅₅N structure and of surface plasmon resonances of silver nanoprisms. In comparison to other approaches, the technique is less prone to inelastic delocalization and relativistic artefacts. The mixed contribution of elastic and inelastic contrast is discussed.