Picosecond laser ultrasonic measurements of interlayer elastic properties of 2H-MoSe2 and 2H-WSe2
Picosecond laser ultrasonic measurements of interlayer elastic properties of 2H-MoSe2 and 2H-WSe2
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DOI：
10.1016/j.mtchem.2020.100369
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发表时间：
2020-12
影响因子：
7.3
通讯作者：
E. Thompson;E. Manzella;E. Murray;M. Pelletier;J. Stuligross;B. C. Daly;Seng Huat Lee;R. Redwing
中科院分区：
文献类型：
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作者：
E. Thompson;E. Manzella;E. Murray;M. Pelletier;J. Stuligross;B. C. Daly;Seng Huat Lee;R. Redwing
我们已经使用了超快泵浦-探测技术称为皮秒超声波产生和检测相干声学声子脉冲频率达到40 GHz的剥离晶体的MoSe 2和WSe 2的Si和蓝宝石衬底。我们报告皮秒时间分辨的反射率数据，从180 nm到920 nm的厚度范围内的样品，并比较我们的结果，应变引起的光学反射率的变化的一维模拟。我们发现，沿着轴（层间方向）的纵向声速为2800 m/s ± 40 m/s的MoSe 2和2510 m/s ± 60 m/s的WSe 2。我们还报告了测得的接近40 GHz的纵向声学声子的寿命为0.85 ± 0.2 ns，并将此值与弛豫阻尼和3-声子模型的预测进行比较，以及讨论其与MoSe 2的预测热导率的关系。
We have used the ultrafast pump-probe technique known as picosecond ultrasonics to generate and detect coherent acoustic phonon pulses with frequencies reaching 40 GHz in exfoliated crystals of MoSe2and WSe2on Si and sapphire substrates. We report picosecond time-resolved reflectivity data from samples ranging from 180 nm to 920 nm in thickness and compare our results to a 1D simulation of strain-induced changes in the optical reflectivity. We find the longitudinal sound velocity along thec-axis (the interlayer direction) to be 2800 m/s ± 40 m/s for MoSe2and 2510 m/s ± 60 m/s for WSe2. We also report the measured lifetime of longitudinal acoustic phonons approaching 40 GHz to be 0.85 ± 0.2 ns and compare this value with predictions of relaxation damping and 3-phonon models, as well as discuss its relationship to the predicted thermal conductivity of MoSe2.