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Research Highlight

Charging and Imaging Defects On and In PdSe2

Charging and Imaging Defects On and In PdSe2
Top: STM images of three types of vacancy defects in PdSe2: surface VSe (red), sublayer VSe (green), sublayer VPd (blue). Due to charging, atomic defects are magnified to show protrusion around VPd (blue circle) and crater-like feature around VSe (red and green circles). Bottom: Atomic-resolution STM images of defects.

Scientific Achievement

The screened Coulomb interaction between an STM tip and charged single atom vacancy creates large-scale features around individual defects. This effect magnifies sublayer defects to make them visible.

Significance and Impact

By gating the probe, STM and AFM can be used to characterize sublayer atomic defects in a nondestructive way.

Research Details

Scanning tunneling microscopy (STM) and spectroscopy (STS) were combined with density functional theory (DFT) calculations to identify the atomic and electronic structures of pristine and various intrinsic vacancy defects in PdSe2.

Vacancies are charged by tip-gating, resulting in a protrusion around Palladium vacancies (VPd) and crater-like features around Selenium vacancies (Vse).

M. Fu, L. Liang, Q. Zou, G. D. Nguyen, K. Xiao, A.-P. Li, J. Kang, Z. Wu, and Z. Gai, "Defects in Highly Anisotroic Transition-Metal Dichalcogenide PdSe2," J. Phys. Chem. Lett. (2019). DOI: 10.1021/acs.jpclett.9b03312