Current Transport and Phase Transition in MoTe₂

MoTe₂ is an interesting two-dimensional (2D) material, which has small energy barrier between semiconducting 2H phase and metallic 1T′ phase, and has ambipolar transport with high carrier mobility, which makes it promising for phase-change memories and logic devices. In this work, we systematically studied the current transport and phase transition in MoTe₂. The spectral photocurrent measurement reveals that the bandgap of MoTe₂ is ~1eV. The bandgap of MoTe₂ was also extracted using temperature dependence of conductance. The mobility of MoTe₂ was characterized using Hall-bar devices. At low temperatures, the carrier mobility is limited by Columbic scattering, while at high temperatures, it is limited by phonon scattering. Vertical metal/MoTe₂/metal junctions were also fabricated. As the current or voltage applied to the junction increases, MoTe₂ exhibits two transitions: high-to-low resistance transition at medium current levels, and low-to-high resistance transition at high current levels. These two transitions in resistivity in MoTe₂ may correspond to the 2H-to-1T phase transition and 1T-to-amorphous state transition respectively.