Structural stability and intriguing electronic properties of two-dimensional transition metal dichalcogenide alloys

Abstract

Based on the first-principles calculations, we systematically studied the structures and electronic properties of two-dimensional (2D) transition metal dichalcogenide (TMD) alloys with half-to-half mixing of S and Se. Using the chemical potentials of S and Se, the energetic phase diagrams for both single phases and mixed phases of TMD were constructed. A new heterolayer structure (for Sc and Ti) and alternating structure (for Cr, Mn, Fe, Zr, Mo, and W) were proposed for the first time, which were thermodynamically stable for MSSe alloys under the S-poor (relatively low chemical potential of S) and Se-rich (relatively high chemical potential of Se) conditions, and further compared with the disordered structures. Moreover, band gaps, carrier effective mass, and work functions were calculated for these stable mixed phases. Compared to the single phases of MS and MSe, MSSe alloys showed superior electronic properties including tunable band gaps and work functions. Importantly, the significantly reduced effective mass of the carriers in the MSSe alloys may induce higher carrier mobility, providing better performance of TMD materials in electronic devices.

An emerging Janus MoSeTe material for potential applications in optoelectronic devices

“…Additionally, the structures and electronic properties of 2D TMD alloys with halfto-half mixing of S and Se for Sc, Ti, Cr, Mn, Fe, Zr, Mo and W were studied for the first time. 27 However, currently, a comprehensive study to estimate the transmittance, absorbance, and reflectance (TAR) of 2D materials is very scarce, which is essential for analyzing their efficiency as ultrathin reflectors, transmitters or absorbers. For example, one may think that 2D materials are so thin that they should appear to be essentially transparent with negligible reflection and absorption.…”

One-Step Growth of Spatially Graded Mo1–xWxS2 Monolayers with a Wide Span in Composition (from x = 0 to 1) at a Large Scale

“…Actually, there are two favorable factors for growing alloyed TMC heterojunctions, in contrast to the 3D-structured semiconductors. First, from the point view of thermodynamics, the absence of direct chemical bonding between the alloyed elements favors entropy rather enthalpy-dominated mixing of alloy; , hence, stable and completely mixed alloy can be formed at high temperatures . Second, the exempt requirement on lattice match between TMCs and underlying substrates, because of their weak van der Waals interaction, makes it possible to grow the compositionally distributed and lattice constant spatially varied 2D materials on a single chip.…”

Quantum beats of coherent 1s 2s excitons in two dimensional transition metal

“…The parameters used to determine exciton eigenvalues and eigenfunctions as well as the substrate dielectric constants (SiO 2 , hBN) are listed in the table bellow. [66] 4.26 [66] 6.15 [14] 6.12 [67] 3.183 [67] The convergence of the numerical diagonalisation is obtained for first 10 states but we only restrict ourselves to 1s and 2s states. For zero magnetic field Molas et al [68] have shown that the only the first 5 |ns states can be observed.…”