Intrinsic Donor-Bound Excitons in Ultraclean Monolayer Semiconductors

Abstract

The monolayer transition metal dichalcogenides are an emergent semiconductor platform exhibiting rich excitonic physics with coupled spin-valley degree of freedom and optical addressability. Here, we report a new series of low energy excitonic emission lines in the photoluminescence spectrum of ultraclean monolayer WSe2. These excitonic satellites are composed of three major peaks with energy separations matching known phonons, and appear only with electron doping. They possess homogenous spatial and spectral distribution, strong power saturation, and anomalously long population (> 6 $\mu$s) and polarization lifetimes (> 100 ns). Resonant excitation of the free inter- and intra-valley bright trions leads to opposite optical orientation of the satellites, while excitation of the free dark trion resonance suppresses the satellites photoluminescence. Defect-controlled crystal synthesis and scanning tunneling microscopy measurements provide corroboration that these features are dark excitons bound to dilute donors, along with associated phonon replicas. Our work opens opportunities to engineer homogenous single emitters and explore collective quantum optical phenomena using intrinsic donor-bound excitons in ultraclean 2D semiconductors.

arXiv commentto be appear in Nature Communications

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• Spatially indirect intervalley excitons in bilayer WSe2
• Strain control of exciton and trion spin-valley dynamics in monolayer transition metal dichalcogenides
• Extrinsic localized excitons in patterned 2D semiconductors
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• Optical properties of MoSe${}_2$ monolayer implanted with ultra-low energy Cr ions
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• Flat-band-induced many-body interactions and exciton complexes in a layered semiconductor
• Uniform Narrow Excitonic Spectrum in Large-Area Suspended WSe2 Monolayers
• Deterministic and Scalable Quantum Light Generation in DNA Origami-Programmed Organic Molecule-MoS${}_2$ Monolayer Hybrids