Thermal stability of VSe2 investigated by in situ transmission electron microscope

Two-dimensional (2D) materials with the ultrathin morphology and versatile electronic properties are promising candidates for the advanced electronics. The metallic 2D vanadium diselenide (VSe
2
) with high conductivity could be applied as the electrode material for 2D-material-based sensors and transistors. Due to the atomically thin structure, the thermal stability of the 2D material is critical for both device fabrication and reliable application. However, the understanding of the failure mechanism is deficient. This work presents a mechanism of thermal induced defect that is not reported by in situ thermal transmission electron microscope. Different from 2H-MoS
2
that generates vacancies, the 1T-VSe
2
presents phase transition from VSe
2
to V2Se
9
at 300 °C, and the phase transition is irreversible. This work offers the experimental support for the new understanding of thermal stability of 2D materials.