Stacking‐Tuned Phonon Renormalization and Effective Heat Transport in Moiré Semiconductor Superlattices

Abstract

ABSTRACT Optically driven moiré semiconductor bilayers involve coupled phonon anharmonicity, interlayer interactions, and local heat dissipation, but experimental benchmarks across supported homo‐ and heterobilayers remain limited. Here, we combine temperature‐dependent Raman spectroscopy, excitation‐power‐dependent Raman thermometry, and photoluminescence to study twisted MoS 2 /MoS 2 , WS 2 /WS 2 , and MoS 2 /WS 2 bilayers. From 90 to 300 K, both homobilayers show conventional softening of Raman‐active phonons with negative effective anharmonic coefficients. In contrast, the WS 2 ‐derived out‐of‐plane A ‐mode in the MoS 2 /WS 2 heterobilayer hardens with increasing temperature, exhibiting a positive linear temperature coefficient of +0.00700 ± 0.00029 cm − 1 K − 1 and a positive effective Balkanski coefficient of +1.28 ± 0.19 cm − 1 , while other modes remain softening‐dominant. Photoluminescence reveals an interlayer excitonic channel only in the heterobilayer, indicating an interface‐specific phonon renormalization pathway beyond equilibrium anharmonic decay. Using two excitation objectives with distinct laser‐heating radii, the supported Raman thermometry resolves mode‐dependent effective thermal‐transport parameters and reduces covariance in extracting in‐plane heat‐transport and heat‐sinking coefficients. We further develop a physics‐guided monolayer‐to‐stacked neural‐network framework to reconstruct Raman spectra across temperature and power conditions and identify optimal optothermal regimes. These results establish heterointerface‐controlled phonon renormalization as a key factor in phonon dynamics controlling heat dissipation and provide a scalable platform for thermal design in moiré quantum devices.