Controlled growth of 2D heterostructures and prevention of TMD oxidation

This paper presents a review of the controlled growth of transition metal dichalcogenide (TMD) heterostructures, and the elucidation of the role of underlying two dimensional (2D) materials on temporal degradation of transition metal dichalcogenides (TMDs). Chemical vapor deposition (CVD)-growth is carried out to achieve localized, patterned, single crystalline or polycrystalline monolayers of TMDs, including MoS₂, WS₂, WSe₂ and MoSe₂, as well as their heterostructures. The localized growth of TMDs has an important implication for nonlinear optics applications. Extensive material characterization is performed to illuminate the role of dissimilar 2D substrates in the prevention of interior defects in TMDs. This characterization provides a detailed observation of the oxidation rates and behaviors of TMDs, which corroborate the role of underlying 2D layers in the prevention of in-air oxidation in TMDs. The epitaxial growth is demonstrated to create TMDs on hBN and graphene, as well as vertical/lateral heterostructures of TMDs, uniquely forming in-phase 2D heterostructures.