Atomically thin MoSe2 is of interest from the perspective of estimating the layer-dependent material properties necessary for the translation of two-dimensional materials into devices. This work presents Raman spectroscopic protocols to determine a multitude of material parameters of two-dimensional MoSe2 films, including the layer thickness as well as the layer-dependent thermal conductivity, interlayer interactions, and anharmonicity. The Davydov splitting (factor-group splitting) observed in an out-of-plane A1g Raman mode, being layer-dependent in both the number and the peak positions, provides a method for estimating the number of layers. Furthermore, this work demonstrates the determination of the thermal conductivity (K) from the temperature-dependent Davydov split Raman modes of the multi-layers. The measurement of K by conventional methods is otherwise challenging for the micrometer sizes of the two-dimensional materials. The value of K thus determined increases significantly from 9 W m−1 K−1 for a four-layer thick MoSe2 film to 52 W m−1 K−1 for a monolayer. The diminishing effect of anharmonicity observed in the monolayer as compared to multi-layer MoSe2 supports the layer-dependent trend in the thermal conductivity. Overall, the findings are relevant for the applications of 2D MoSe2 in low power electronic, optoelectronic, and thermoelectric devices.
Raman spectroscopic study of the layer-dependent Davydov splitting and thermal conductivity of chemically vapor deposited two-dimensional MoSe2
Note: This paper is part of the APL Special Collection on Phononics of Graphene, Layered Materials, and Heterostructures.
Vineeta Singh, V. G. Sathe, Shyama Rath; Raman spectroscopic study of the layer-dependent Davydov splitting and thermal conductivity of chemically vapor deposited two-dimensional MoSe2. Appl. Phys. Lett. 23 January 2023; 122 (4): 042201. https://doi.org/10.1063/5.0123628
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