Achieving full spectrum of atomically thin 2D TMDs by CVD: From monolayers to alloys, heterostructures, and superlattices

Intensive research into atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs) has revealed remarkable physicochemical properties, positioning them as promising candidates for advanced functional electronic and optoelectronic devices beyond conventional silicon-based technologies. Beyond pristine monolayer TMDs with diverse elemental compositions, the development of compositionally tunable alloys, heterostructures, and superlattices composed of distinct TMDs has enabled the exploration of emergent physical phenomena and functionalities. However, the controllable synthesis of large-area, high-quality 2D TMDs with well-defined compositions and architectures remains a fundamental prerequisite for both basic research and practical applications. While mechanical exfoliation has been extensively adopted for constructing TMDs-based heterostructures and superlattices, it lacks scalability and structural precision. In contrast, chemical vapor deposition (CVD) has emerged as a versatile and scalable approach for synthesizing a broad spectrum of TMDs including monolayers, alloys, vertical/lateral heterostructures, and superlattices. This review provides a comprehensive and critical overview of recent progress in the CVD synthesis of 2D TMDs. Particular attention is given to nucleation and growth mechanisms, and the structural and functional diversity achieved through alloying and hetero-integration. Finally, we outline key challenges and promising directions for future research in this rapidly evolving field.