Coupling of MoS$_{2}$ thin films with different substrates probed by temperature dependent Raman Spectroscopy

Few-layer MoS$_{2}$ is emerging as a new 2-D material beyond graphene, showing a number of interesting properties that could lead to applications in optoelectronics. In most if not all real applications, the MoS$_{2}$ films are expected to be supported by substrates, thus the film-substrate coupling is inevitable. In this work, we study the temperature-dependent Raman shifts of both in-plane (E$_{\mathrm{2g}}^{1})$ and out-of-plane (A$_{\mathrm{1g}})$ phonon modes for single-layer and bi-layer MoS$_{2}$ films on different substrates in a temperature range of 25 -- 500 $^{\circ}$C. By investigating the temperature dependence of Raman scattering, we show that, with increasing temperature, the chemical bonding between film and substrate introduces a damping to E$_{\mathrm{2g}}^{1}$ Raman temperature shift for the MoS$_{2}$ thin-film grown on sapphire by CVD, while the changes in the film morphology leads to significant nonlinear effects for the A$_{\mathrm{1g}}$ mode, such as nonlinear sometimes even non-monotonic temperature shift of Raman frequency and temperature dependence of Raman linewidth, for the transferred MoS$_{2}$ thin-film on SiO$_{2}$/Si substrate.