Surface Optical Rectification from Layered MoS2 Crystal by THz Time Domain Surface Emission Spectroscopy
Surface Optical Rectification from Layered MoS2 Crystal by THz Time Domain Surface Emission Spectroscopy
复制标题
通过太赫兹时域表面发射光谱对层状 MoS2 晶体进行表面光学整流
DOI：
10.1021/acsami.6b13961
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发表时间：
2017-02-08
影响因子：
9.5
通讯作者：
Xu, Xinlong
中科院分区：
文献类型：
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作者：
Huang, Yuanyuan;Zhu, Lipeng;Xu, Xinlong
利用太赫兹（THz）时域表面发射光谱技术，在线偏振飞秒激光激发下，观察了层状半导体二硫化钼（MoS2）晶体的表面光整流效应. MoS2的太赫兹辐射幅度与泵浦能量密度成线性关系，与泵浦电场成二次函数关系，区别于InAs中表面Doppler场诱导的太赫兹辐射和石墨中瞬态光电流诱导的太赫兹产生。基于MoS2晶体空间对称性的理论分析表明，其产生THz辐射的机制是反射结构下的表面光整流。这是一致的实验结果，根据辐射太赫兹振幅依赖于方位角和入射偏振角。我们还证明了由于微观键断裂的二硫化钼在飞秒激光照射下，这可以通过太赫兹时域发射光谱和拉曼光谱监测的损伤阈值。
Surface optical rectification was observed from the layered semiconductor molybdenum disulfide (MoS2) crystal via terahertz (THz) time-domain surface emission spectroscopy under linearly polarized femtosecond laser excitation. The radiated THz amplitude of MoS2 has a linear dependence on ever-increasing pump fluence and thus quadratic with the pump electric field, which discriminates from the surface Dember field induced THz radiation in InAs and the transient photocurrent-induced THz generation in graphite. Theoretical analysis based on space symmetry of MoS2 crystal suggests that the underlying mechanism of THz radiation is surface optical rectification under the reflection configuration. This is consistent with the experimental results according to the radiated THz amplitude dependences on azimuthal and incident polarization angles. We also demonstrated the damage threshold of MoS2 due to microscopic bond breaking under the femtosecond laser irradiation, which can be monitored via THz time-domain emission spectroscopy and Raman spectroscopy.