Near-unity light absorption in a monolayer WS2 van der Waals heterostructure cavity

TL;DR

This paper demonstrates near-unity light absorption in a monolayer WS2 heterostructure cavity, revealing fundamental limits and mechanisms of light-exciton interactions in 2D materials, with implications for optoelectronic applications.

Contribution

It introduces a TMD-based heterostructure cavity achieving near-unity excitonic absorption, supported by a quantum theoretical framework explaining the underlying physical mechanisms.

Findings

Achieved near-unity excitonic absorption in monolayer WS2

Observed emission at ultra-low excitation powers

Unveiled a universal absorption law for 2D excitons

Abstract

Excitons in monolayer transition-metal-dichalcogenides (TMDs) dominate their optical response and exhibit strong light-matter interactions with lifetime-limited emission. While various approaches have been applied to enhance light-exciton interactions in TMDs, the achieved strength have been far below unity, and a complete picture of its underlying physical mechanisms and fundamental limits has not been provided. Here, we introduce a TMD-based van der Waals heterostructure cavity that provides near-unity excitonic absorption, and emission of excitonic complexes that are observed at ultra-low excitation powers. Our results are in full agreement with a quantum theoretical framework introduced to describe the light-exciton-cavity interaction. We find that the subtle interplay between the radiative, non-radiative and dephasing decay rates plays a crucial role, and unveil a universal absorption law for excitons in 2D systems. This enhanced light-exciton interaction provides a platform for studying excitonic phase-transitions and quantum nonlinearities and enables new possibilities for 2D semiconductor-based optoelectronic devices.