Metal-organic chemical vapour deposition of van der Waals 2D chalcogenides and heterostructures: a review

van der Waals (vdW) two-dimensional (2D) transition metal chalcogenides have garnered increasing attention from academia and industry due to their unique physical properties and device-relevant functionalities. However, a key challenge remains for 2D semiconductors to be integrated into practical electronic and optoelectronic systems: achieving wafer-scale synthesis of high-quality 2D films under conditions compatible with back-end-of-line (BEOL) processing. In this review, we highlight recent advances in metal-organic chemical vapour deposition (MOCVD) as a promising technique for the uniform and scalable growth of 2D chalcogenides. We first provide a comprehensive overview of the synthesis strategies, emphasising critical aspects such as precursor chemistry and the thermodynamic/kinetic factors that govern crystal growth. We then discuss achieving epitaxial alignment and monolayer uniformity over large areas, which are essential for the growth of single-crystalline 2D wafers. Attention is also given to the interplay between the substrate and the growing film and their effects and methods for forming vertical and lateral heterostructures during MOCVD. We further review recent efforts to grow non-group-VI 2D vdW chalcogenides to offer a broader perspective on how their synthesis pathways and structural diversity can be engineered.