A Hybrid-DFT Study of Intrinsic Point Defects in $M{X}_2$ ($M$=Mo, W; $X$=S, Se) Monolayers

Abstract

Defects can strongly influence the electronic, optical and mechanical properties of 2D materials, making defect stability under different thermodynamic conditions crucial for material-property engineering. In this paper, we present an account of the structural and electronic characteristics of point defects in monolayer transition metal dichalcogenides $M{X}_2$ with $M$=Mo/W and $X$= S/Se, calculated with density-functional theory using the hybrid HSE06 exchange correlation functional including many-body dispersion corrections. For the simulation of charged defects, we employ a charge compensation scheme based on the virtual crystal approximation (VCA). We relate the stability and the electronic structure of charged vacancy defects in monolayer MoS${}_2$ to an explicit calculation of the S monovacancy in MoS${}_2$ supported on Au(111), and find convincing indication that the defect is negatively charged. Moreover, we show that the finite-temperature vibrational contributions to the free energy of defect formation can change the stability transition between adatoms and monovacancies by 300--400 K. Finally, we probe defect vibrational properties by calculating a tip-enhanced Raman scattering image of a vibrational mode of a MoS${}_2$ cluster with and without an S monovacancy.

References in corpus (5)

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• Strong Photoluminescence Enhancement of MoS2 through Defect Engineering and Oxygen Bonding
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Cited by in corpus (4)

• First-Principles Simulations of Tip Enhanced Raman Scattering Reveal Active Role of Substrate on High-Resolution Images
• Electronic and magnetic properties of single chalcogen vacancies in MoS${}_2$/Au(111)
• An atomic-scale perspective on individual thiol-terminated molecules anchored to single S vacancies in MoS${}_2$
• Radiative electronic bound states in the continuum from defects in semiconductors