Role of Optical Phonons in Bulk Molybdenum Diselenide Thermal Properties Probed by Advanced Raman Spectroscopy,Physica Status Solidi (B) - Basic Solid State Physics

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Role of Optical Phonons in Bulk Molybdenum Diselenide Thermal Properties Probed by Advanced Raman Spectroscopy
Physica Status Solidi (B) - Basic Solid State Physics ( IF 1.5 ) Pub Date : 2020-06-03 , DOI: 10.1002/pssb.202000251
Zuo-Yuan Dong _{1,

2} , Ya-Kang Peng ₂ , Hao Yu ₂ , Wei-Jian Li ₂ , Jia-Wei Hu ₂ , Chen Luo ₁ , Xing Wu ₁ , Xiao-Jia Chen ₂

Affiliation

The solid‐state‐based thermoelectric (TE) materials have attracted considerable interest for their potential application in energy conversion. In general, high‐frequency optical phonon modes are always thought to have a negligible contribution to thermal transport due to their short mean free path. Herein, the optical phonons effect in bulk molybdenum diselenide (MoSe₂) is studied using advanced low‐wavenumber Raman spectroscopy with a wide temperature range. It is found that the cubic anharmonicity is dominant at low temperatures, and quartic anharmonicity becomes gradually stronger with increasing temperature. The obtained

E_{2 g}^{1}

mode is the most susceptible to the anharmonicity effect and has high phonon density of states (DOS). This is an effect that cannot be explained by previous TE models and, therefore, offers new insight into the nature of phonon transport in 2D materials. The results reveal that the thermal transport can be regulated via high‐frequency phonon scattering.

中文翻译：

光学声子在高级拉曼光谱探测的大体积二硒化钼热性能中的作用

固态热电（TE）材料因其在能量转换中的潜在应用而引起了极大的兴趣。通常，由于高频光子模式的平均自由程短，通常认为它们对热传输的贡献微不足道。在此，使用先进的低波数拉曼光谱技术在较宽的温度范围内研究了散装二硒化钼（MoSe ₂）中的光子效应。发现在低温下立方非谐性占主导，并且随着温度升高四次非谐性逐渐增强。获得的