Temperature controlled single-step growth of MoS₂/WS₂ heterostructures via NaCl-assisted low pressure chemical vapor deposition

2D heterostructures of transition metal dichalcogenides (TMDs) have received significant interest due to their interesting and excellent electrical, optical and electrocatalytic properties which provide a wider platform to research nanomaterials and design atomically thin devices. However, large area growth of high quality TMD- based heterostructures still remains a challenge. The conventional synthesis process of these heterostructures suffers from some critical limitations such as low yield and non-reproducibility. In this work, we synthesize MoS₂/WS₂ few-layer heterostructures using a single-step, halide-assisted low-pressure chemical vapor deposition and study the effect of temperature, carrier gas flow rate and relative amount of MoO₃ and WO₃ precursors in the structure, morphology and optical properties of the sample. We observed few layer MoS₂/WS₂ heterostructures of size up to 30 µm (WS₂, bottom) and 6 µm (MoS₂, top) for growth temperature of 780 °C. The heterostructures are characterized using optical microscopy, Raman spectroscopy, Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). This work provides a straight- forward method for the controllable growth of large area 2D heterostructures which are significant for potential device applications.