1 research outputs found
Raman Characterization of the Charge Density Wave Phase of 1T-TiSe<sub>2</sub>: From Bulk to Atomically Thin Layers
Raman
scattering is a powerful tool for investigating the vibrational
properties of two-dimensional materials. Unlike the 2H phase of many
transition metal dichalcogenides, the 1T phase of TiSe<sub>2</sub> features a Raman-active shearing and breathing mode, both of which
shift toward lower energy with increasing number of layers. By systematically
studying the Raman signal of 1T-TiSe<sub>2</sub> in dependence of
the sheet thickness, we demonstrate that the charge density wave transition
of this compound can be reliably determined from the temperature dependence
of the peak position of the E<sub>g</sub> mode near 136 cm<sup>–1</sup>. The phase transition temperature is found to first increase with
decreasing thickness of the sheets, followed by a decrease due to
the effect of surface oxidation. The Raman spectroscopy-based method
is expected to be applicable also to other 1T-phase transition metal
dichalcogenides featuring a charge density wave transition and represents
a valuable complement to electrical transport-based approaches