Temperature dependence Raman spectroscopy studies of CVD grown few layer MoS2 triangular domains

Abstract

The effect of thermal perturbations on different Raman-active phonon modes was investigated using temperature-dependent Raman Spectroscopy of few layers MoS2 triangular domains (FMTD). The MoS2 triangular domains were prepared using the chemical vapour deposition (CVD) method and were characterised using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction, and micro Raman spectroscopy. The micro Raman spectra of few FMTD recorded at higher temperatures (above room temperature) and were analysed using a theoretical framework developed by taking hot phonon anharmonicity into account. Temperature-dependent responses for the E12g, A1g, and 2LA(M) modes soften as the temperature rises from 25 °C to 300 °C. The first-order temperature coefficients of MoS2 triangular domains, E12g, A1g, and 2LA(M) modes are −0.018 cm-1K−1, −0.015 cm-1K−1, and −0.017 cm-1K−1, respectively. The experimental results revealed that phonon–phonon kinematics played a dominant role in broadening and peak shifts in the Raman mode, confirming the anharmonic effect's prevalence. Three or four phonon decay processes were used to explain the boarding and redshift in the peak position of temperature-dependent Raman mode. Moreover, thermal management is so crucial to the performance of low-dimensional devices, our findings pave the way for improved design strategies in this field.