Atomic-Level Dynamics of Point Vacancies and the Induced Stretched Defects in 2D Monolayer PtSe2

Jun Chen; Jiang Zhou; Wenshuo Xu; Yi Wen; Yuanyue Liu; Jamie H Warner

doi:10.1021/acs.nanolett.1c04275

Atomic-Level Dynamics of Point Vacancies and the Induced Stretched Defects in 2D Monolayer PtSe₂

Nano Lett. 2022 Apr 27;22(8):3289-3297. doi: 10.1021/acs.nanolett.1c04275. Epub 2022 Apr 7.

Authors

Jun Chen¹, Jiang Zhou^{2

3}, Wenshuo Xu¹, Yi Wen¹, Yuanyue Liu², Jamie H Warner^{2

4}

Affiliations

¹ Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom.
² Materials Graduate Program, Texas Materials Institute, The University of Texas at Austin, 204 East Dean Keeton Street, Austin, Texas 78712, United States.
³ Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China.
⁴ Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.

PMID: 35389659
DOI: 10.1021/acs.nanolett.1c04275

Abstract

Monolayer PtSe₂ holds great potential in extending 2D devices functionality, but their atomic-level-defect study is still limited. Here, we investigate the atomic structures of lattice imperfections from point to stretched 1D defects in 1T-PtSe₂ monolayers, using annular dark-field scanning transmission electron microscopy (ADF-STEM). We show Se vacancies (V_Se) have preferential sites with high beam-induced mobility. Diverse divacancies form with paired V_Se. We found stretched linear defects triggered by dynamics of V_Se that altered strain fields, distinct from the line vacancies in 2H-phase 2D materials. The paired V_Se stability and formation possibility of vacancy lines are evaluated by density functional theory. Lower sputtering energy in PtSe₂ than that in MoS₂ can cause larger possibility of atomic loss compared to diffusion required for creating V_Se lines. This provides atomic insights into the defects in 1T-PtSe₂ and shows how a deviated 1D structure is embedded in a 2D system without losing atom lines.

Keywords: 2D Materials; Defects; PtSe2; STEM; Vacancies.