Imaging Strain-Localized Single-Photon Emitters in Layered GaSe below the Diffraction Limit

TL;DR

This study demonstrates nanoscale strain control of single-photon emitters in layered GaSe, achieving wavelength tunability and brightness enhancement below the diffraction limit, advancing quantum photonics applications.

Contribution

It provides the first detailed nanoscale analysis of strain effects on GaSe SPEs using correlative microscopy and simulations, surpassing diffraction limitations.

Findings

Strain-localized SPEs emit from 620 nm to 900 nm.

Achieved ~100 nm spectral tunability of SPEs.

Observed two-orders of magnitude brightness enhancement.

Abstract

Nanoscale strain control of exciton funneling is an increasingly critical tool for the scalable production of single photon emitters (SPEs) in two-dimensional materials. However, conventional far-field optical microscopies remain constrained in spatial resolution by the diffraction limit and thus can only provide a limited description of nanoscale strain localization of SPEs. Here, we quantify the effects of nanoscale heterogeneous strain on the energy and brightness of GaSe SPEs on nanopillars with correlative cathodoluminescence, photoluminescence, and atomic force microscopies supported by density functional theory simulations. We report the strain-localized SPEs have a broad range of emission wavelengths from 620 nm to 900 nm. We reveal substantial strain-controlled SPE wavelength tunability over a ~ 100 nm spectral range and two-orders of magnitude enhancement in the SPE brightness at the pillar center due to Type-I exciton funneling. In addition, we show that radiative biexciton cascade processes contribute to the observed CL photon superbunching. Also, the measured GaSe SPE photophysics after electron beam exposure shows the excellent stability of these SPEs. We anticipate this insight into nanoscale strain control of two-dimensional SPEs will guide the development of truly deterministic quantum photonics.