Yang Shichao, Chen Wenwei, Sa Baisheng, Guo Zhiyong, Zheng Jingying, Pei Jiajie, Zhan Hongbing
College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China.
Fujian Science & Technology Innovatation Laboratory for Optoelectronic Information, Fuzhou 350108, Fujian, Peoples Republic of China.
Nano Lett. 2023 Apr 12;23(7):3070-3077. doi: 10.1021/acs.nanolett.3c00771. Epub 2023 Mar 30.
Triggered by the expanding demands of semiconductor devices, strain engineering of two-dimensional transition metal dichalcogenides (TMDs) has garnered considerable research interest. Through steady-state measurements, strain has been proved in terms of its modulation of electronic energy bands and optoelectronic properties in TMDs. However, the influence of strain on the spin-orbit coupling as well as its related valley excitonic dynamics remains elusive. Here, we demonstrate the effect of strain on the excitonic dynamics of monolayer WS via steady-state fluorescence and transient absorption spectroscopy. Combined with theoretical calculations, we found that tensile strain can reduce the spin-splitting value of the conduction band and lead to transitions between different exciton states via spin-flip mechanism. Our findings suggest that the spin-flip process is strain-dependent, provides a reference for application of valleytronic devices, where tensile strain is usually existing during their design and fabrication.
受半导体器件不断增长的需求推动，二维过渡金属二硫属化物（TMDs）的应变工程已引起了相当大的研究兴趣。通过稳态测量，已证明应变对TMDs的电子能带和光电特性具有调制作用。然而，应变对自旋轨道耦合及其相关的谷激子动力学的影响仍然难以捉摸。在这里，我们通过稳态荧光和瞬态吸收光谱法证明了应变对单层WS激子动力学的影响。结合理论计算，我们发现拉伸应变可以降低导带的自旋分裂值，并通过自旋翻转机制导致不同激子态之间的跃迁。我们的研究结果表明，自旋翻转过程是应变依赖的，为谷电子器件的应用提供了参考，在谷电子器件的设计和制造过程中通常存在拉伸应变。
