Nucleation promoted synthesis of large-area ReS2 film for high-speed photodetectors.

Abstract

Rhenium disulfide (ReS2) is a transition metal dichalcogenide with a layer-independent direct bandgap. Notably, the weak interlayer coupling owing to its T-phase structure enables multilayer ReS2to behave similar to decoupled monolayers. This inherent characteristic makes continuous multi-layer ReS2film a unique platform for large-area electronic applications. To date, the bulk of work on ReS2has been conducted using mechanically exfoliated samples or small size flakes (< 1mm2) with no potential for large-scale electronics. A chemical vapor deposition (CVD) synthesis of a large area, continuous ReS2film directly on a SiO2substrate is also known to be more challenging compared with that of other 2D materials, such as MoS2and WS2. This is partly due to its tendency to grow into discrete dendritic structures. In this study, a large-area (> 1 cm2), continuous multilayer ReS2film is directly synthesized on a SiO2substrate without any transfer process. The polycrystalline ReS2film synthesized by this method exhibits one of the fastest photoresponse speeds (0.8 s rise time and 0.37 s decay time) among the reported CVD films. The responsivity Rλwas also the highest among large-area CVD films. The synthesis method for a continuous multilayer ReS2film is amenable to large-scale integration and will pave the way for practical optoelectronic applications based on 2D layered materials.