Abstract
We report low-frequency Raman scattering results of bilayer (2L) MoS2 structures with 3R and 2H stacking orders. The stacking orders were identified by Raman mapping images of the low-frequency shear (S) and layer breathing (B) modes. Linear temperature coefficients (χ) were obtained from temperature-dependent frequency changes of the shear and layer breathing modes for the 3R- and 2H-stacked 2L MoS2: χ3RS=−0.011±0.006cm−1/K, χ2HS=−0.009±0.002cm−1/K, χ3RB=−0.009±0.003cm−1/K, and χ2HB=−0.010±0.002cm−1/K. Interestingly, the temperature coefficients were significantly reduced after the MoS2 samples were thermally heated: χ3RS=−0.004±0.001cm−1/K, χ2HS=−0.004±0.001cm−1/K, χ3RB=−0.002±0.001cm−1/K, and χ2HB=−0.002±0.001cm−1/K. Similar behaviors were also observed for the temperature coefficients of the high-frequency E2g1 and A1g phonons. The heating-induced modifications in the temperature coefficients are attributed to changes in the MoS2–substrate coupling. Our result further paves the way for optimal design strategies for low-dimensional device applications where thermal management plays a crucial role in device performance.
Published Version
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