期刊
NANO LETTERS
卷 19, 期 7, 页码 4745-4751出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b01829
关键词
2D materials; MoS2 monolayer; thermal expansion coefficient; micro-Raman spectroscopy; three-substrate approach; phonon deformation potential
类别
资金
- MIT/MTL GaN Energy Initiative
- Singapore-MIT Alliance for Research and Technology (SMART) LEES Program
- Air Force Office of Scientific Research [FA9550-15-1-0310]
- DURIP program from the Office of Naval Research (ONR) [N00014-17-1-2363]
Atomically thin two-dimensional (2D) materials have shown great potential for applications in nanoscale electronic and optical devices. A fundamental property of these 2D flakes that needs to be well-characterized is the thermal expansion coefficient (TEC), which is instrumental to the dry transfer process and thermal management of 2D material-based devices. However, most of the current studies of 2D materials' TEC extensively rely on simulations due to the difficulty of performing experimental measurements on an atomically thin, micron-sized, and optically transparent 2D flake. In this work, we present a three-substrate approach to characterize the TEC of monolayer molybdenum disulfide (MoS2) using micro-Raman spectroscopy. The temperature dependence of the Raman peak shift was characterized with three different substrate conditions, from which the in-plane TEC of monolayer MoS2 was extracted on the basis of lattice symmetries. Independently from two different phonon modes of MoS2, we measured the in-plane TECs as (7.6 +/- 0.9) X 10(-6) K-1 and (7.4 +/- 0.5) x 10(-6) K-1, respectively, which are in good agreement with previously reported values based on first-principle calculations. Our work is not only useful for thermal mismatch reduction during material transfer or device operation but also provides a general experimental method that does not rely on simulations to study key properties of 2D materials.
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