Prediction of the structural and electronic properties of Mo_xTi_1−xS₂ monolayers via first principle simulations

Abstract

Two-dimensional transition metal dichalcogenides have gained great attention because of their peculiar physical properties that make them interesting for a wide range of applications. Lately, alloying between different transition metal dichalcogenides has been proposed as an approach to control two-dimensional phase stability and to obtain compounds with tailored characteristics. In this theoretical study, we predict the phase diagram and the electronic properties of Mo xTi1− xS2 at varying stoichiometry and show how the material is metallic, when titanium is the predominant species, while it behaves as a p-doped semiconductor, when approaching pure MoS2 composition. Correspondingly, the thermodynamically most stable phase switches from the tetragonal to the hexagonal one. Further, we present an example which shows how the proposed alloys can be used to obtain new vertical two-dimensional heterostructures achieving effective electron/hole separation.

Theoretical Investigation of Optoelectronics Properties of Titanium Dichalcogenides Materials TiX₂ (X=S, Se, Te) Using Quantum Espresso

“…3.a that this material has a semi-metal composition because the valence band maximum is at the (0,0,0) point and the conduction band minimum is at the L (1/2,0,1/2) point with a band gap of 0.05 eV. This result agrees with the results of the ab-initio calculation done by [13], and [33]. While TiS2 was supposed to have a semi-conductor character and an indirect gap of about 1.9 eV, according to Allan et al [7] A metallic character is observed for TiSe2 and TiTe2 which show an overlap of the valence and conduction band (Fig.…”

First principles study of photogalvanic effect of monolayer SnS

“…These superior properties make TMDCs a promising new materials for innovative sensors, optoelectronic devices, highly sensitive photodetection, quantum communication devices, and so on. [15][16][17][18][19] Recently, black phosphorus photodetector has been demonstrated that it can operate under bias with a very low dark current and attain an intrinsic responsivity up to 135 mA W À1 and 657 mA W À1 in 11.5 nm and 100 nm thick devices at room temperature. 20 With the advent of the post molar era, there is a growing demand for nanodevices with high response and sensitivity.…”

Stability and Bandgap Engineering of In1−xGaxSe Monolayer

“…For photonic applications, it is required to develop 2D materials with continuous tunable bandgaps, and doping is one of the best techniques that can be exploited for this purpose [19]. Substitutional defects in a pristine monolayer may lead to a change in the lattice structure of the host material, resulting in a wide range bandgap tunability [20,21]. In our recent work [22], we defected 2D InSe with different substitutional impurities to generate well-defined and sharp defect states within the bandgap of the material, and we showed the possibility of using these new energy levels to achieve efficient emissions of single photons [23,24].…”