Time- and spatially-resolved optical spectroscopy of MoS2 monolayers

我们建议使用各种光学光谱技术来研究化合物半导体MoS2的单层性质。与石墨一样，二硫化钼是一种具有明显层状结构的材料，其中各层由共价键强烈束缚，而层间耦合由弱范德华力介导。大块二硫化钼是一种间接间隙半导体。然而，在2010年证明，如果它被薄到单层，它会显示出明显的光致发光，并且DFT计算预测了单层的直接带隙。MoS2中的传导态和价带态是由类d Mo轨道形成的，与III-V半导体中的类s态和类p态形成鲜明对比。我们想利用光致发光和光致发光激发在低温和高磁场下研究二硫化钼的能带结构。MoS2单层晶体结构的一个直接结果是自旋和谷自由度之间的耦合，这将导致新的光电效应，如谷霍尔效应。我们建议在时间和空间分辨光学实验中研究二硫化钼单层中的载流子、自旋和谷动力学，以观察预测的效果。

We propose to investigate the properties of monolayers of the compound semiconductor MoS2 using various optical spectroscopy techniques. MoS2, like graphite, is a material with a pronounced layer structure, where individual layers are strongly bound by covalent bounds, while interlayer coupling is mediated by weak van der Waals forces. Bulk MoS2 is an indirect-gap semiconductor. However, it was demonstrated in 2010 that it shows pronounced photoluminescence if it is thinned to a single layer, and DFT calculations predict a direct bandgap for a monolayer. Conduction and valence band states in MoS2 are formed from d-like Mo orbitals, in stark contrast to the s- and p-like states in III-V semiconductors. We want to investigate the band structure of MoS2 using photoluminescence and photoluminescence excitation at low temperatures and in high magnetic fields. A direct consequence of the crystal structure of MoS2 monolayers is the coupling between spin and valley degrees of freedom, which should lead to new opto-electronic effects, such as the Valley Hall effect. We propose to study the carrier, spin and valley dynamics in MoS2 monolayers in time- and spatially-resolved optical experiments in order to observe the predicted effects.