(439b) Lateral Growth of Two-Dimensional 1H-WSe2/1T’-WTe2 Heterostructures

Two-dimensional (2D) transition metal dichalcogenides (TMDs) such as MoS₂, MoSe₂, WS₂, and WSe₂, have attracted great attention due to their unique properties and atomic thickness. Until recently, great success was achieved in synthesizing 2D TMDs in 1T’ phase, such as 1T’-MoTe₂ and WTe₂, which is particularly interesting due to they are predicted to be large-gap quantum spin Hall topological insulators [Qian et al. Science 2014, 346, 1344−1347]. Exploring the full potential of these 2D TMDs requires precise spatial modulation of their chemical composition and electronic properties to create well-defined heterostructures.

Here we report for the first time the growth of 1H-WSe₂/1T’-WTe₂ heterostructures by a two-step chemical vapor deposition method. The 1H-WSe2 was synthesized first, followed by an epitaxial growth of 1T’-WTe₂ on the edge. Monolayer thickness of the two flakes was confirmed by atomic force microscopy. Raman mapping studies demonstrated that the resulting heterostructures exhibited clear structure and phase modulation. Transmission electron microscopy revealed a single crystalline structure and a clear transition between the two different phases. Electrical transport studies demonstrated the formation of lateral p-type semiconductor and semi-metal heterojunctions by the combination of WSe₂ and WTe₂. This work provides an important advance in developing layered semiconductor-semimetal heterostructures and is an essential step towards next-generation nanoelectronic devices.