Visualization of Laser-induced Phase Transition in Few-layer MoTe2

Phase transition between different polymorphs of two-dimensional (2D) transition metal dichalcogenides (TMDs) is of great interest for the development of 2D electronics. Here, we report the visualization of laser-induced 2H-to-1T’ phase transition in few-layer molybdenum ditelluride (MoTe₂) nanosheet by microwave impedance microscopy (MIM). The MIM allows noninvasive measurement of conductivity contrast between the metallic 1T’ phase and semiconducting 2H phase, which is confirmed by Raman mapping on the same sample. The results are further corroborated by photoconductivity imaging under above-gap illumination. As expected, the intact 2H region displays strong photoresponse, whereas the laser-treated 1T’ region shows no detectable photoconductivity. The spatially resolved information is important for correlating electrical and structural properties in various TMDs undergoing laser-driven phase transition.