Many-body and spin-orbit effects on direct-indirect band gap transition of strained monolayer MoS${}_2$ and WS${}_2$

Abstract

Monolayer transition metal dichalcogenides are promising materials for photoelectronic devices. Among them, molybdenum disulphide (MoS${}_2$) and tungsten disulphide (WS${}_2$) are some of the best candidates due to their favorable band gap values and band edge alignments. Here we consider various perturbative corrections to the DFT electronic structure, e.g. GW, spin-orbit coupling, as well as many-body excitonic and trionic effects, and calculate accurate band gaps as a function of homogeneous strain in these materials. We show that all of these corrections are of comparable magnitudes and need to be included in order to obtain an accurate electronic structure. We calculate the strain at which the direct-to-indirect gap transition occurs. After considering all contributions, the direct to indirect gap transition strain is found to be at 2.7% in MoS${}_2$ and 3.9% in WS${}_2$. These values are generally higher than the previously reported theoretical values.

arXiv comment9 pages, 4 figures, 1 table

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• Impact of strain on the optical fingerprint of monolayer transition metal dichalcogenides
• Weakly Trapped, Charged, and Free Excitons in Single-Layer MoS2 in the Presence of Defects, Strain, and Charged Impurities
• Multifaceted moiré superlattice physics in twisted WSe${}_2$ bilayers
• Strain-controlled spin splitting in the conduction band of monolayer WS2
• Heterobilayers of 2D materials as a platform for excitonic superfluidity
• Inverse Funnel Effect of Excitons in Strained Black Phosphorus
• Theoretical phase diagram for the room temperature Electron-Hole Liquid in photo-excited quasi-2D monolayer MoS${}_2$
• Critical assessment of $G_0{W}_0$ calculations for 2D materials: the example of monolayer MoS${}_2$
• Enhanced Spin-Flip Scattering by Surface Roughness in WS${}_2$ and MoS${}_2$ Armchair Nanoribbons
• Zero point motion and direct/indirect bandgap crossover in layered transition-metal dichalcogenides
• Strain induced topological phase transition at zigzag edges of monolayer transition-metal dichalcogenides
• Benchmarking exchange-correlation potentials with the mstar60 dataset: Importance of the nonlocal exchange potential for effective mass calculations in semiconductors
• Strain-induced activation of chiral-phonon emission in monolayer WS${}_2$
• Proximity-induced topological transition and strain-induced charge transfer in graphene/MoS2 bilayer heterostructures
• Strain-dependent resistance and giant gauge factor in monolayer WSe2