Pressure effect on the electronic, structural, and vibrational properties of layered 2H-MoTe2

Layered molybdenum dichalchogenides differ from the classic example of bilayer graphene with their unique electronic properties: the application of pressure can continuously tune electronic structure since the band gap is controlled by delicate interlayer interaction. Here, we have performed measurements of Raman scattering, synchrotron x-ray diffraction, electrical conductivity, and Hall coefficient combined with density functional theory calculations to synthetically study the pressure effect on 2H-MoTe2. Both the experiments and calculations consistently demonstrate that MoTe2 undergoes a semiconductor-to-metallic (S-M) transition above 10 GPa. Unlike MoS2, the S-M transition is driven by the gradual tunability of electric structure and band gap without structural transition. The applied pressure also effectively enhances conductivity and carrier concentration while reducing the mobility, which makes MoTe2 more suitable for applications than most other transition-metal dichalchogenides and allows it to be applied in strain-modulated optoelectronic devices.