Substrate-Dependence of Monolayer MoS Thermal Conductivity and Thermal Boundary Conductance
arXiv:2204.11381 · doi:10.1063/5.0089247
Abstract
The thermal properties of two-dimensional (2D) materials, like MoS, are known to be affected by interactions with their environment, but this has primarily been studied only with SiO substrates. Here, we compare the thermal conductivity (TC) and thermal boundary conductance (TBC) of monolayer MoS on amorphous (a-) and crystalline (c-) SiO, AlN, AlO, and -BN monolayers using molecular dynamics. The room temperature TC of MoS is ~38 WmK on amorphous substrates and up to ~68 WmK on crystalline substrates, with most of the difference due to substrate interactions with long-wavelength MoS phonons (< 2 THz). An -BN monolayer used as a buffer between MoS and the substrate causes the MoS TC to increase by up to 50%. Length-dependent calculations reveal TC size effects below ~2 m and show that the MoS TC is size- but not substrate-limited below ~100 nm. We also find that the TBC of MoS with c-AlO is over twice that with c-AlN despite a similar MoS TC on both, indicating that the TC and TBC could be tuned independently. Finally, we compare the thermal resistance of MoS transistors on all substrates to show that MoS TBC is the most important parameter for heat removal for long-channel (> 150 nm) devices, while TBC and TC are equally important for short channels. This work provides important insights for electro-thermal applications of 2D materials on various substrates.
16 Pages, 6 Figures, Supplementary Information
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