Fine structures of valley-polarized excitonic states in monolayer transitional metal dichalcogenides

Nanophotonics

article

Zhipeng Li¹  Tianmeng Wang¹  Shengnan Miao¹  Zhen Lian¹  Su-Fei Shi¹ 

[1] Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute;School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University;Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute

关键词: excitonic complexes;    exciton–phonon interaction;    transition metal dichalcogenides;    optoelectronics;   

DOI  :  10.1515/nanoph-2020-0054

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

Monolayer transitional metal dichalcogenides (TMDCs), a new class of atomically thin semiconductor, respond to optical excitation strongly with robust excitons, which stem from the reduced screening in two dimensions. These excitons also possess a new quantum degree of freedom known as valley spin, which has inspired the field of valleytronics. The strongly enhanced Coulomb interaction allows the exciton to bind with other particles to form new excitonic states. However, despite the discovery of trions, most of the excitonic states in monolayer TMDCs remain elusive until recently, when new light was shed into the fascinating excitonic fine structures with drastically improved sample quality through boron nitride encapsulation. Here, we review the latest research progress on fine structures of excitonic states in monolayer TMDCs, with a focus on tungsten-based TMDCs and related alloy. Many of the new excitonic complexes inherit the valley degree of freedom, and the valley-polarized dark excitonic states are of particular interest because of their long lifetime and possible long valley coherence time. The capability of resolving the excitonic fine structures also enables the investigation of exciton–phonon interactions. The knowledge of the interlayer between excitons and other particles not only advances our understanding of many-body effects in the monolayer TMDCs but also provides guidance on future applications based on TMDCs.

【 授权许可】

CC BY