Orientation dependent thermal behavior of CVD grown few layer MoS2 films

Abstract

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.