Drift-dominant exciton funneling and trion conversion in 2D semiconductors on the nanogap.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35119920.
- Also identified by DOI 10.1126/sciadv.abm5236 and PMC identifier 8816338.
- Licence recorded as CC BY-NC.
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Abstract
Understanding and controlling the nanoscale transport of excitonic quasiparticles in atomically thin two-dimensional (2D) semiconductors are crucial to produce highly efficient nano-excitonic devices. Here, we present a nanogap device to selectively confine excitons or trions of 2D transition metal dichalcogenides at the nanoscale, facilitated by the drift-dominant exciton funneling into the strain-induced local spot. We investigate the spatiospectral characteristics of the funneled excitons in a WSe<sub>2</sub> monolayer (ML) and converted trions in a MoS<sub>2</sub> ML using hyperspectral tip-enhanced photoluminescence imaging with <15-nm spatial resolution. In addition, we dynamically control the exciton funneling and trion conversion rate by the gigapascal-scale tip pressure engineering. Through a drift-diffusion model, we confirm an exciton funneling efficiency of ∼25% with a significantly low strain threshold (∼0.1%), which sufficiently exceeds the efficiency of ∼3% in previous studies. This work provides a previously unexplored strategy to facilitate efficient exciton transport and trion conversion of 2D semiconductor devices.