Controllable Laser-Induced Phase Transition in Multilayer 2H-MoTe2 and its Raman Spectroscopy Study

Abstract

Transition metal dichalcogenides (TMDCs) heterojunctions, with their atomically precise planar structures, enable the formation of smooth and well-matched interfaces between different TMDCs components, effectively mitigating performance losses caused by lattice mismatches and rendering them highly suitable for applications in advanced devices, including 2D photodetectors, flexible light-emitting diodes, high-mobility field-effect transistors, and solar cells. Lateral heterojunctions, owing to the covalent bonding between distinct phases, demonstrate high carrier mobility, significantly lowering the contact resistance at the interface. However, the fabrication of lateral TMDCs heterojunctions is limited by several factors, including randomness, interfacial quality, and process reproducibility. In this study, a straightforward laser irradiation method for inducing phase transitions in MoTe₂ is presented. By optimizing the laser power and exposure duration, multilayer 2H-MoTe₂ encapsulated with h-BN is successfully transformed into the 1T′ phase, as verified by Raman spectroscopy. Moreover, temperature-dependent Raman spectroscopy is performed on the laser-induced 1T′-MoTe₂, which demonstrated the transformation into the T_d phase at ≈230K, suggesting the high structural quality of the laser-irradiated 1T′-MoTe₂. These results demonstrate a practical approach for phase engineering of MoTe₂, providing valuable insights into the fabrication of lateral heterojunctions and their future applications in high-performance photoelectric devices.