DFT study of structural and electronic properties of MoS2(1−x)Se2x alloy (x = 0.25)

Abstract

First-principles calculations have been performed to study the structural features of the monolayer MoS2(1-x)Se2x (x = 0.25) alloy and its electronic properties. We studied the effects of the relative positions of Se atoms in a real monolayer alloy. It was demonstrated that the distribution of the Se atoms between the top and bottom chalcogen planes was most energetically favorable. For a more probable distribution of Se atoms, a MoS2(1-x)Se2x (x = 0.25) monolayer alloy is a direct semiconductor with a fundamental band gap equal to 2.35 eV (calculated with the GVJ-2e method). We also evaluated the optical band gap of the alloy at 77 K (1.86 eV) and at room temperature (1.80 eV), which was in good agreement with the experimentally measured band gap of 1.79 eV.

Recent Developments in Controlled Vapor‐Phase Growth of 2D Group 6 Transition Metal Dichalcogenides

“…[215] Another frequent use of DFT is for the determination of electronic properties of various complete 2D TMD layers (under various conditions such as strain, alloying, and doping), [210,213,216] or of layers with low coverage of precursors, simulations of STM images, [10,217] local density of states (DOS) and others. [218] Such electronic structure calculations have little to do with the mechanisms of nucleation and growth, but are often used i) to provide a guide of the range of attainable electronic properties of heterostructures or alloyed TMDs, [50,[219][220][221][222] and ii) to assess the validity of various hypotheses posited by collaborative experimental investigations. [10,214] Direct quantum molecular dynamics (MD) simulations of growth are currently feasible, but often for system sizes and time scales that could presently be too small to be considered relevant for experimental conditions.…”

Atomic‐Level Customization of 4 in. Transition Metal Dichalcogenide Multilayer Alloys for Industrial Applications

“…In addition, previous studies have proposed that if the first Se substitution occurred at the top chalcogen plane, the second Se substitution at the bottom chalcogen plane was more energetically favorable than the substitution at the same plane. [39] Additionally, we studied the correlation among the relative concentration of bichalcogen atoms, the x values of the MoS 2(1−x) Se 2x alloy, and the activa tion energies for the selenization process governed by reaction pathway 1, as displayed in Figure 5e. The activation energies for the selenization of MoS 2(1−x) Se 2x (x = 0, 0.17, 0.33, 0.44, 0.78, and 0.94) acquired from NEB calculations increase linearly with increasing Se content.…”

“…Based on the calculation of the activation energies of the two possible pathways under various circumstances, we conclude that pathway 1 is more energetically favorable for the substitution of Se in the MoS 2 backbone. In addition, previous studies have proposed that if the first Se substitution occurred at the top chalcogen plane, the second Se substitution at the bottom chalcogen plane was more energetically favorable than the substitution at the same plane . Additionally, we studied the correlation among the relative concentration of bichalcogen atoms, the x values of the MoS 2(1− x ) Se 2 x alloy, and the activation energies for the selenization process governed by reaction pathway 1, as displayed in Figure e.…”

Prediction of the structural and electronic properties of MoxTi1−xS2 monolayers via first principle simulations

“…14 Another promising strategy, currently employed to engineer TMD monolayers, consists of alloying two different TMD compounds. 15 –17 Typically, it is either possible to substitute part of the metal atoms of a given MX 2 with a different metal species (M′) which also exist in the form of a 2D structure (M′X 2 ) to obtain M x M′ 1− x X 2 alloys or it is possible to replace X with a different chalcogen atom (X′) to obtain MX x X′ 2− x . In limited cases, the possibility to vary both the metal and the chalcogen species has been explored.…”