Orientation dependent thermal behavior of CVD grown few layer MoS2 films

Differently oriented supported MoS₂ nanostructures are ideal candidates for various electronic and optoelectronic applications, with their performance influenced by thermal properties and is still not comprehensively studied. In this paper, we study the temperature-dependent Raman response of CVD synthesized horizontally (H-MoS₂) and vertically (V-MoS₂) oriented MoS₂ grown over SiO₂-Si substrate from 80 to 333 K. The V-MoS₂ shows a relatively higher peak shift, attributed to its smaller contact area with the substrate, giving it a suspended-like characteristic. Then to facilitate quantitative understanding of the non-linear temperature dependency in differently oriented MoS₂ films, a physical model incorporating both volume and thermal effect is employed. The greater four-phonon contribution for in-plane mode of H-MoS₂ compared to V-MoS₂ may be attributed to the larger contact area with the substrate, leading to higher-order scattering due to interface formation. Our study can be leveraged for understanding thermal response in future applications of low-power thermoelectric and optoelectronic devices.