论文标题
Terahertz光谱探测的Mose的超快光电$ _2 $
Ultrafast photocurrents in MoSe$_2$ probed by terahertz spectroscopy
论文作者
论文摘要
我们使用Terahertz（THZ）发射光谱来研究原型2D半导体，过渡金属二甲基元素摩西摩西$ _2 $中的飞秒光电动力学。我们确定了几种响应于双层（BL）和多层（ML）样品的超平元（$ 30 \，$ fs）光激发的不同机制。在ML中，由于光激发荷载载流子在地面电场中漂移，因此通过平面电流在皮秒时间尺度上产生THZ辐射。 BL发射由平面移位电流产生。最后，我们观察到BL样品排放中的振荡约为23美元。我们将振荡归因于两个激子状态之间的量子节拍，其能量分离为$ \ sim100 \，$ mev。
We use the terahertz (THz) emission spectroscopy to study femtosecond photocurrent dynamics in the prototypical 2D semiconductor, transition metal dichalcogenide MoSe$_2$. We identify several distinct mechanisms producing THz radiation in response to an ultrashort ($30\,$fs) optical excitation in a bilayer (BL) and a multilayer (ML) sample. In the ML, the THz radiation is generated at a picosecond timescale by out-of-plane currents due to the drift of photoexcited charge carriers in the surface electric field. The BL emission is generated by an in-plane shift current. Finally, we observe oscillations at about $23\,$THz in the emission from the BL sample. We attribute the oscillations to quantum beats between two excitonic states with energetic separation of $\sim100\,$meV.
