Tailoring the Valley-Polarized Emission of Monolayer TMDs at Room Temperature for Future Quantum Information Technology

Wei-Hsiang Lin^1*

¹Department of Physics, National Chung Hsing University (NCHU), Taichung, Taiwan

* Presenter:Wei-Hsiang Lin, email:whl@phys.nchu.edu.tw

Monolayer transition metal dichalcogenides (TMDs) have intrinsic valley degrees of freedom, making them appealing for exploiting valleytronic applications in information storage and processing. WS2 monolayer possesses two inequivalent valleys in the Brillouin zone, each valley coupling selectively with a circular polarization of light. The degree of valley polarization (DVP) under the excitation of circularly polarized light (CPL) is a parameter that determines the purity of valley polarized photoluminescence (PL) of monolayer WS2. In this work, I will present three strategies for tailoring valley polarization at room temperature (RT) to advance the development of practical, application-oriented valleytronic devices. First, I will demonstrate how ultra-compact plasmonic Archimedes spiral (PAS) nanostructures can enhance light–matter interactions through surface plasmons, thereby effectively modulating the valley-polarized photoluminescence (PL) of monolayer WS₂ at RT. Next, I will show a significantly enhanced DVP and electrical tunability in the valley-polarized emission from 1T′-WTe₂/WTe₀.₁₂S₁.₈₈ heterostructures. Finally, I will introduce my recent progress on ferroelectric Bi₂O₂Se nanosheets and discuss ongoing efforts to integrate them into valleytronic device architectures, paving the way for electrically tunable and energy-efficient valley-based technologies. These methodologies describe in this talk provide a promising platform to manipulate the valley degrees of freedom in TMDs efficiently at RT, paving ways for future applications of opto-valleytronic/spintronic devices based on these 2D materials.

References:
1. Lin, W.H.*; Li, C.-S.; Wu C.-I; Rossman, G. R.; Atwater, H. A* and Yeh, N.-C.*, Dramatically
Enhanced Valley-Polarized Emission by Alloying and Electrical Tuning of Monolayer
WTe2xS2(1-x) Alloys at Room Temperature with 1T′-WTe2-Contact. Advanced Science 2023,
11(2), 2304890.
2. Lin, W.-H.*; Wu, P. C.; Akbari, H.; Rossman, G. R.; Yeh, N.-C.*; Atwater, H. A*. Electrically
Tunable and Dramatically Enhanced Valley-Polarized Emission of Monolayer WS2 at Room
Temperature with Plasmonic Archimedes Spiral Nanostructures. Advanced Materials 2022, 34
(3), 2104863.

Keywords: 2D materials, valleytronics, exciton-plasmon interaction, chiral plasmonic metasurface, ternary 2D alloys