Abstract
In this work, we report a universal dual-metal precursors method with the use of a mixture of a metal and its chloride as the source to grow various non-layered 2D TMCs. Using this method, we can control the evaporation rate to provide a constant metal supply and facilitate the growth of non-layered 2D TMCs. Taking Fe1−xS as an example, flakes as thin as 3 nm with a lateral size over 100 μm are grown.
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Two-dimensional (2D) transition metal chalcogenides (TMCs) are promising for nanoelectronics and energy applications. Among them, the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surface and strong intralayer and interlayer bonding. However, the synthesis of non-layered 2D TMCs is challenging and this has made it difficult to study their structures and properties at thin thickness limit. Here, we develop a universal dual-metal precursors method to grow non-layered TMCs in which a mixture of a metal and its chloride serves as the metal source. Taking hexagonal Fe1–xS as an example, the thickness of the Fe1–xS flakes is down to 3 nm with a lateral size of over 100 μm. Importantly, we find ordered cation Fe vacancies in Fe1–xS, which is distinct from layered TMCs like MoS2 where anion vacancies are commonly observed. Low-temperature transport measurements and theoretical calculations show that 2D Fe1–xS is a stable semiconductor with a narrow bandgap of ∼60 meV. In addition to Fe1–xS, the method is universal in growing various non-layered 2D TMCs containing ordered cation vacancies, including Fe1–xSe, Co1–xS, Cr1–xS, and V1–xS. This work paves the way to grow and exploit properties of non-layered materials at 2D thickness limit.