Photoluminescence imaging of single photon emitters within nanoscale strain profiles in monolayer WSe$_2$

TL;DR

This study uses photoluminescence imaging and atomic force microscopy to locate and analyze strain-induced single-photon emitters in monolayer WSe2, revealing their microscopic origin related to strain effects on excitonic states.

Contribution

It provides detailed spatial and strain profile analysis of single-photon emitters in monolayer WSe2, elucidating their microscopic formation mechanism.

Findings

Single-photon emitters with 98% purity identified in WSe2

Strain-induced spectral shifts of dark excitons linked to emission

Localized defect states hybridize with excitonic states

Abstract

Local deformation of atomically thin van der Waals materials provides a powerful approach to create site-controlled chip-compatible single-photon emitters (SPEs). However, the microscopic mechanisms underlying the formation of such strain-induced SPEs are still not fully clear, which hinders further efforts in their deterministic integration with nanophotonic structures for developing practical on-chip sources of quantum light. Here we investigate SPEs with single-photon purity up to 98% created in monolayer WSe$_2$ via nanoindentation. Using photoluminescence imaging in combination with atomic force microscopy, we locate single-photon emitting sites on a deep sub-wavelength spatial scale and reconstruct the details of the surrounding local strain potential. The obtained results suggest that the origin of the observed single-photon emission is likely related to strain-induced spectral shift of dark excitonic states and their hybridization with localized states of individual defects.