In Situ Characterization of Phase Transition and Defect Dynamics in Molybdenum Ditelluride

Transition metal dichalcogenides (TMDs) are regarded as promising materials for emerging applications, including electronic devices, photonic devices, biosensors, and energy storage, etc. Owing to their novel structures and extraordinary properties, they have provided the researchers with an excellent platform to explore low-dimensional physics. However, some challenges need to be resolved before their practical application. The phases and defects in TMDs can significantly affect their properties. Therefore, understanding the phase transition and defects in TMDs would be of great importance to advance their further application. This dissertation focuses on the identification and characterization of a novel phase transition from two dimensional MoTe2 phase to one dimensional Mo6Te6 nanowire phase during the vacuum annealing. Furthermore, the thermal stability of MoTe2 is extensively investigated. In particular, the inversion domain boundaries formed during the vacuum annealing are identified to be a defective interface in MoTe2. The role of Te vacancy to the evolution of inversion domain boundaries is extensively studied. Also, a possible strategy to improve its thermal stability is demonstrated.