Temperature- and power-dependent phonon properties of suspended few layers of tungsten diselenide

In this study we report the temperature- and laser power-dependence of the out-of-plane A(1g) Raman mode of mechanically exfoliated few-layered WSe2 suspended on Si3N4 holes. The A(1g) phonon frequency is red-shifted for a temperature in the range 77-548 K, with first-order temperature coefficients estimated to be -0.0083 and -0.0079 cm(-1)/K for suspended four- and six-layer WSe2, respectively. The laser power-dependence of suspended four-layer WSe2 sample is estimated to be -0.0079 cm(-1)/mu W and no shift is observed for six-layer WSe2. By using the laser power-dependence of the suspended four layers WSe2 and the 1D Balandin's approach, we calculate the in-plane thermal conductivity of WSe2 at room temperature to be similar to 57.7 W/m K.