We studied the role of biaxial compressive strain in laser-induced anharmonicity effects of mono- and bilayer MoS₂ grown by chemical vapor deposition. With the increased laser powers, the A_1g phonon mode was strongly affected by the anharmonicity, whereas the E¹_2g mode was negligibly affected by the anharmonic effects, which is attributed to the dominant nature of biaxial compressive strain over the effects of anharmonicity. In the case of the A_1g phonon mode, anharmonicity effects dominated over the biaxial compressive strain owing to its large out-of-plane thermal expansion coefficient. The origin of biaxial compressive strain was explained by invoking the difference in linear thermal expansion coefficients of MoS₂ and the substrate. Moreover, thermally induced biaxial compressive strain also influenced the exciton emission energy. The role of the substrate thermal conductivity was discussed in the light of anharmonicity of the MoS₂ monolayer. In addition, the polarizability of Raman modes was found to be dependent on the second layer arrangement over the monolayer.

中文翻译：

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通过CVD生长的单层和双层MoS2中的激光诱导的非谐性与热诱导的双轴压缩应变

我们研究了双轴压缩应变在通过化学气相沉积法生长的单层和双层MoS ₂激光诱导的非谐效应中的作用。随着激光功率的增加，A _1g声子模受到非谐性的强烈影响，而E ¹ _2g模受到非谐性的影响可忽略不计，这归因于双轴压缩应变相对于非谐性的主导性质。在A _1g的情况下在声子模式下，由于其大的面外热膨胀系数，非谐性效应在双轴压缩应变中占主导地位。通过调用MoS ₂和基板的线性热膨胀系数的差异来解释双轴压缩应变的起源。此外，热诱导的双轴压缩应变也影响了激子发射能量。鉴于MoS ₂单层的非谐性，讨论了衬底导热性的作用。另外，发现拉曼模式的极化率取决于单层上的第二层布置。