PubCard - Switching of K-Q intervalley trions fine structure and their dynamics in n-doped monolayer WS₂

(Peer-Reviewed) Switching of K-Q intervalley trions fine structure and their dynamics in n-doped monolayer WS₂

Jiajie Pei 裴家杰 ¹ ², Xue Liu 刘学 ³, Andrés Granados del Águila ³, Di Bao 鲍迪 ³, Sheng Liu 刘盛 ³, Mohamed-Raouf AMARA ³, Weijie Zhao 赵伟杰 ³, Feng Zhang 张峰 ¹, Congya You 游聪雅 ⁴, Yongzhe Zhang 张永哲 ⁴, Kenji Watanabe ⁵, Takashi Taniguchi ⁵, Han Zhang 张晗 ¹, Qihua Xiong 熊启华 ⁶

¹ Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
中国深圳深圳大学物理与光电工程学院二维材料光电科技国际合作联合实验室光电科技协同创新中心
² College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China
中国福州福州大学材料科学与工程学院
³ Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
⁴ College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
中国北京北京理工大学材料学院
⁵ Research Center for Functional Materials, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
⁶ State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
中国北京清华大学物理系低维量子物理国家重点实验室

Opto-Electronic Advances, 2022-10-28

https://doi.org/10.29026/oea.2023.220034

https://www.oejournal.org/article/doi/10.29026/oea.2023.220034

Abstract

Monolayer group VI transition metal dichalcogenides (TMDs) have recently emerged as promising candidates for photonic and opto-valleytronic applications. The optoelectronic properties of these atomically-thin semiconducting crystals are strongly governed by the tightly bound electron-hole pairs such as excitons and trions (charged excitons).

The anomalous spin and valley configurations at the conduction band edges in monolayer WS₂ give rise to even more fascinating valley many-body complexes. Here we find that the indirect Q valley in the first Brillouin zone of monolayer WS₂ plays a critical role in the formation of a new excitonic state, which has not been well studied.

By employing a high-quality h-BN encapsulated WS₂ field-effect transistor, we are able to switch the electron concentration within K-Q valleys at conduction band edges. Consequently, a distinct emission feature could be excited at the high electron doping region. Such feature has a competing population with the K valley trion, and experiences nonlinear power-law response and lifetime dynamics under doping.

Our findings open up a new avenue for the study of valley many-body physics and quantum optics in semiconducting 2D materials, as well as provide a promising way of valley manipulation for next-generation entangled photonic devices.