Growth of two-dimensional Janus MoSSe by a single in situ process without initial or follow-up treatments

Abstract

Two-dimensional (2D) Janus transition metal dichalcogenides (TMDCs) are highly attractive as an emerging class of 2D materials, but only a few methods are available for fabricating them. These methods rely on the initial growth of 2D TMDCs in one process, followed by an additional plasma or high-temperature (T) process. To overcome these drawbacks, we employ the new approach of NaCl-assisted single-process chemical vapor deposition, which consists of three steps that proceed only by altering the temperature in situ. In the first step, MoS2 is deposited onto a SiO2/Si substrate with the Mo and S atoms activated in different temperature zones. In the second step, S vacancies are formed in the upper layer of the grown MoS2 by annealing. In the third step, the vacancies are filled with activated Se atoms. Throughout the steps, NaCl lowers the melting point of the constituent atoms, while the T in each zone is properly controlled. The growth mechanism is clarified by a separate annealing experiment that does not involve a supply of activated atoms. These results highlight a simple and cost-effective approach for growing Janus MoSSe, which is more useful for fundamental studies and device applications.

Angular Dependence of the Second-Order Nonlinear Optical Response in Janus Transition Metal Dichalcogenide Monolayers

“…Several polar group VI two-dimensional (2D) transition metal dichalcogenides (TMDs), that is, TMD monolayers composed of a trilayer of atoms with different chalcogens on each side (MXY structure, space group P 3 m 1 (#156); point group C 3 v ), have been theoretically proposed for a variety of applications, including catalysis, − gas sensing, and piezoelectricity. , The subsequent experimental realization of these materials has been forthcoming, − including a synthesis technique that allows real-time monitoring of the growth process by in situ spectroscopy, improving the optical quality of these grown materials. Interest in these materials stems from the difference in the chalcogen atoms within the individual monolayer.…”

Crystal growth of the 2D Janus rhodium chalcohalide RhSeCl

“…12 The Janus concept represents a novel form of functionalisation, and the interest in these materials is growing rapidly. So far, only a few representatives of 2D Janus materials have been reported, for example, graphenebased Janus-layers, 13 Janus transition metal dichalcogenides such as MoSSe 14 and 2D Janus chalcohalides such as BiTeCl. 11,15 However, there is a large gap between the theoretical predictions and the experimental results, which is probably related to the difficulties in sample preparation.…”

Two-dimensional Janus monolayers with tunable electronic and magnetic properties

“…Recently, a new class of 2D materials, called as Janus materials, has gained attention for their fascinating properties. The first studied 2D Janus material was MoSSe [13,14]. These Janus materials show different kinds of behavior than their 2D mother compounds, such as graphene is a semimetal [15] but graphenebased Janus material, known as hydrofluorinated graphene (HGF), is a semiconductor with a direct band gap of 2.82 eV [16] which is useful for graphene-based electronic and optoelectronic applications.…”