Controlled growth of large-area anisotropic ReS₂ atomic layer and its photodetector application

As an anisotropic 2D layered material, rhenium disulfide (ReS₂) has attracted much attention because of its unusual properties and promising applications in electronic and optoelectronic devices. However, the low lattice symmetry and interlayer decoupling of ReS₂ make asymmetric growth and out-of-plane growth occur quite easily; therefore, thick flake, dendritic and flower-like structures of ReS₂ have mostly been obtained previously. Here, we report on an approach based on space-confined epitaxial growth for the controlled synthesis of ReS₂ films. Using this approach, large-area and high-quality ReS₂ films with uniform monolayer thickness can grow on a mica substrate. Furthermore, the weak van der Waals interaction between the surface of mica and ReS₂ clusters, which favors surface-confined growth while avoiding out-of-plane growth, is critical for growing ReS₂ with uniform monolayer thickness. The morphological evolution of ReS₂ with the growth temperature reveals that asymmetric growth can be suppressed at relatively low temperatures. A ReS₂ field-effect transistor displayed a current on/off ratio of 10⁶ and an electron mobility of up to 40 cm² V^-1 s^-1, with outstanding photoresponsivity of 12 A W^-1. This work not only promotes the large-scale employment of ReS₂ in high-performance optoelectronic devices, but also provides a means of controlling the unusual growth behavior of low-lattice-symmetry 2D layered materials.