Temperature dependence of Raman shifts in layered ReSe2 and SnSe2 semiconductor nanosheets

Transition metal dichalcogenides (TMDCs) are attractive for variety of nanoscale electronics and optoelectronics devices due to their unique properties. Despite growing progress in the research field of TMDCs, many of their properties are still unknown. In this letter, we report measurements of Raman spectra of rhenium diselenide (ReSe2) and tin diselenide (SnSe2) layered semiconductor nanosheets as a function of temperature (70-400 K). We analyze the temperature dependence of the positions of eight ReSe2 modes and SnSe2 A(1g) mode. All observed Raman mode shifts exhibit nonlinear temperature dependence at low temperatures which is explained by optical phonon decay process into two or three acoustics phonons. The first order temperature coefficients (chi), determined for high temperatures, of rhenium diselenide Raman modes are in the range between -0.0033 and -0.0118 cm(-1)/K, whereas chi of tin diselenide A(1g) mode was -0.0129 cm(-1)/K. Our findings are useful for further analysis of phonon and thermal properties of these dichalcogenide layered semiconductors. (C) 2015 AIP Publishing LLC.