High‐Electric‐Field‐Induced Phase Transition and Electrical Breakdown of MoTe₂

Abstract

Abstract 2D molybdenum ditelluride (MoTe 2 ) has recently received significant attention due to its unique phase transition and ambipolar behavior as well as thickness‐dependent bandgap. The phase transition and electrical breakdown of various thickness MoTe 2 field‐effect transistors observed under high electric fields are addressed. Interestingly, the MoTe 2 exhibits phase transition from a semiconducting 2H phase to a metallic 1T′ almost simultaneously with electrical breakdown, and this is confirmed by a Raman peak of 1T′‐MoTe 2 at 125 cm −1 . Using Raman mapping results of MoTe 2 FETs obtained after the breakdown, it is revealed that the phase transition is initiated from the metal contacting electrode regions of source and drain. All the Raman peaks of MoTe 2 shifted to low frequency with increasing drain voltage. Based on the Raman peak shifts, the temperature change in the MoTe 2 FETs while device operation is in progress is estimated. The maximum temperature and dissipated power of a tri‐layer MoTe 2 device are found to reach 495 K and 5.85 mW, respectively, at an electric field of 6.5 V µm −1 . This research provides guidelines for circuit design toward the application of 2D semiconductor devices, related to the energy dissipation and electrical breakdown unique to 2D phase transitional materials.