• Corpus ID: 252531231

Emergence of a low-energy excitonic state in single layer WS2 with 1H/1T phase mixture

@inproceedings{Woods2022EmergenceOA,
  title={Emergence of a low-energy excitonic state in single layer WS2 with 1H/1T phase mixture},
  author={John M. Woods and Saroj B. Chand and E. Mejia and Takashi Taniguchi and Kenji Watanabe and Johannes Flick and Gabriele Grosso},
  year={2022}
}

• John M. Woods, S. Chand, +4 authors G. Grosso
• Published 26 September 2022
• Physics

Transition metal dichalcogenides possess a unique combination of properties that make them a malleable platform to study and engineer light-matter interactions. On one hand, monolayers of WS 2 naturally occur in the semiconducting 1H phase whose optical properties are dominated by excitons emerging from the band edges at the K valley. On the other hand, the 1T phase exhibits metallic properties and can be triggered by weak external stimuli. Here we use plasma irradiation to engineer a 1H/1T mixed phase state in WS 2 and control the grain size of the 1T patches by tuning the irradiation time. We show that in the mixed phase WS 2 a band nesting effect gives rise to new critical points resulting in a low-energy excitonic transition below the A exciton. Compared to standard excitons in WS 2 , this new resonance shows larger absorption and longer lifetime. The combination of these properties suggests new concepts for exciton-based optoelectronic devices that could stem from the control of phase mixture states in two-dimensional semiconductors.