Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 48: 2D Materials 1: Electronic Structure of Transition Metal Dichalcogenides
O 48.1: Vortrag
Mittwoch, 7. September 2022, 15:00–15:15, S052
the stability of point defects in 2D monolayer transition metal dichalcogenides and their impact on the electronic structure — •alaa akkoush1,2 and mariana rossi1,2 — 1Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, Berlin — 2MPI for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22765 Hamburg
Defects can strongly influence the electronic, optical and mechanical properties of 1D materials. However, their stability and distribution under different conditions of temperature, pressure and strain are not well characterized from an atomistic perspective. We have investigated the structural and electronic properties, as well as the thermodynamic stability of point defects (vacancies and adatoms) in monolayer transition metal dichalcogenides MX2 with M=Mo/W and X= S/Se, through density-functional theory (DFT) simulations with hybrid exchange correlation functional, as implemented in the all-electron package FHI-aims [1]. These calculations are carried out using a supercell approximation to model localised defects using periodic boundary conditions. We show quantitatively that X adatom is most favorable in rich X conditions while in poor X environment X monovacancy is most favorable. Interestingly, an interplay between adatom and divacancies takes place as temperature increases. To gauge the importance of vibrational free energy contributions on the engineering of gap states in the 2D monolayers, we compare the formation energies of point defects with an adsorbed F6TNAP at various thermodynamic conditions.
[1] S.V. Levchenko , et al., Comp. Phys. Comm. 192 60-69 (2015)