Induction of Phase Transition in Transition Metal Dichalcogenides on Metal Substrates*

Two-dimensional transition metal dichalcogenides (2D-TMDs) possess unique structural phases including the semiconducting 1H and quasi-metallic 1T′ phases. They show intriguing optical and electronic properties. 1H to 1T′ phase transition processes are important to be utilitzed for novel device applications. We present a high-yield 1H to1T′ phase transition of monolayer-MoS₂ on Cu and monolayer-WSe₂ on Au via an annealing-based process. Both experimental and first-principles studies are conducted to study the phase transition mechanism. The 1T' phase yield is increased via interfacial hybridizations enhancement through interfacial binding energy, charge transfer, shorter interfacial spacing, and weaker bond strength.