Image potential states of germanene

Bogdana Borca*, Carolien Castenmiller, Martina Tsvetanova, Kai Sotthewes, Alexander N. Rudenko, Harold J.W. Zandvliet*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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We have measured the two-dimensional image potential states (IPS) of a germanene layer synthesized on a Ge2Pt crystal using scanning tunnelling microscopy and spectroscopy. The IPS spectrum of germanene exhibits several differences as compared to the IPS spectrum of pristine Ge(001). First, the n = 1 peak of the Rydberg series of the IPS spectrum of germanene has two contributions, labelled n = 1- and n = 1+, respectively. The peak at the lower energy side is weaker and is associated to the mirror-symmetric state with opposite parity. The appearance of this peak indicates that the interaction between the germanene layer and the substrate is very weak. Second, the work function of germanene is about 0.75 eV lower in energy than the work function of Ge(001). This large difference in work function of germanene and pristine Ge(001) is in agreement with first-principles calculations.

Original languageEnglish
Article number035021
Journal2D Materials
Issue number3
Publication statusPublished - Jul 2020


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