Imaging the potential distribution of individual charged impurities on graphene by low-energy electron holography

Tatiana Latychevskaia; Flavio Wicki; Conrad Escher; Hans-Werner Fink

doi:10.1016/j.ultramic.2017.07.019

Imaging the potential distribution of individual charged impurities on graphene by low-energy electron holography

Ultramicroscopy. 2017 Nov:182:276-282. doi: 10.1016/j.ultramic.2017.07.019. Epub 2017 Jul 29.

Authors

Tatiana Latychevskaia¹, Flavio Wicki², Conrad Escher², Hans-Werner Fink²

Affiliations

¹ Physics Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. Electronic address: tatiana@physik.uzh.ch.
² Physics Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.

PMID: 28780143
DOI: 10.1016/j.ultramic.2017.07.019

Abstract

While imaging individual atoms can routinely be achieved in high resolution transmission electron microscopy, visualizing the potential distribution of individually charged adsorbates leading to a phase shift of the probing electron wave is still a challenging task. Low-energy electrons (30 - 250 eV) are sensitive to localized potential gradients. We employed low-energy electron holography to acquire in-line holograms of individual charged impurities on free-standing graphene. By applying an iterative phase retrieval reconstruction routine we recover the potential distribution of the localized charged impurities present on free-standing graphene.

Keywords: Charged impurities; Electron holography; Gabor holography; Graphene; In-line holography; Low-energy electrons.