Engineering Thermal Transport across Layered Graphene–MoS2 Superlattices
- Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Univ. of California, Davis, CA (United States)
- Stanford Univ., CA (United States)
- Applied Materials, Inc., Santa Clara, CA (United States)
Layering two-dimensional van der Waals materials provides a high degree of control over atomic placement, which could enable tailoring of vibrational spectra and heat flow at the sub-nanometer scale. In this work, using spatially resolved ultrafast thermoreflectance and spectroscopy, we uncover the design rules governing cross-plane heat transport in superlattices assembled from monolayers of graphene (G) and MoS2 (M). Using a combinatorial experimental approach, we probe nine different stacking sequences, G, GG, MG, GGG, GMG, GGMG, GMGG, GMMG, and GMGMG, and identify the effects of vibrational mismatch, interlayer adhesion, and junction asymmetry on thermal transport. Pure G sequences display evidence of quasi-ballistic transport, whereas adding even a single M layer strongly disrupts heat conduction. The experimental data are described well by molecular dynamics simulations, which include thermal expansion, accounting for the effect of finite temperature on the interlayer spacing. The simulations show that an increase of ~2.4% in the layer separation of GMGMG, relative to its value at 300 K, can lead to a doubling of the thermal resistance. Using these design rules, we experimentally demonstrate a five-layer GMGMG superlattice “thermal metamaterial” with an ultralow effective cross-plane thermal conductivity comparable to that of air.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
- Grant/Contract Number:
- AC02-76SF00515; ECCS-2026822; FA9550-14-1-0251; 1542883; SC0012704
- OSTI ID:
- 1873404
- Journal Information:
- ACS Nano, Vol. 15, Issue 12; ISSN 1936-0851
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Thermal conductivity of the n = –5 and 10 members of the (SrTiO3)n SrO Ruddlesden–Popper superlattices
Thermal Conductivity of HfTe 5 : A Critical Revisit