Visualization of laser-driven phase transition in few-layer MoTe2

Phase transition between different polymorphs of two-dimensional (2D) transition metal dichalcogenides is of great interest for the development of nanoelectronics and optoelectronics. Here, we report the visualization of laser-driven 2H-to-1T′ phase transition in few-layer molybdenum ditelluride (MoTe2) nanosheets by microwave impedance microscopy. The region after intense illumination exhibits clear Raman signatures of the 1T′ phase, as well as much higher local conductance than the untreated area. Moreover, the semiconducting 2H region displays strong photoresponse, whereas the metallic 1T′ region shows little photoconductivity. The spatially resolved information is important for correlating electrical and structural properties in functional 2D materials.