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

Area of Science:

• Materials Science
• Quantum Optics
• Nanotechnology

Background:

• Scalable production of single photon emitters (SPEs) in 2D materials relies on nanoscale strain control.
• Conventional microscopy is limited by diffraction, hindering detailed analysis of strain localization in SPEs.

Purpose of the Study:

• To quantify the impact of nanoscale heterogeneous strain on the energy and brightness of Gallium Selenide (GaSe) SPEs.
• To explore strain-controlled wavelength tunability and brightness enhancement in 2D material SPEs.
• To investigate exciton funneling mechanisms and radiative biexciton cascade processes.

Main Methods:

• Correlative cathodoluminescence, photoluminescence, and atomic force microscopy were employed.
• Density functional theory simulations supported experimental observations.
• Characterization of GaSe SPEs integrated onto nanopillar structures.

Main Results:

• Strain-localized GaSe SPEs exhibit emission wavelengths from 620 to 900 nm.
• A tunable spectral range of approximately 100 nm was achieved through strain engineering.
• SPE brightness was enhanced by two orders of magnitude at the nanopillar center due to Type-I exciton funneling.
• Radiative biexciton cascade processes were identified as contributors to photon superbunching.
• GaSe SPEs demonstrated high stability under electron beam exposure.

Conclusions:

• Nanoscale strain control offers a powerful method for tuning the properties of 2D material SPEs.
• Exciton funneling significantly enhances SPE brightness and spectral characteristics.
• This research provides critical insights for developing deterministic quantum photonics using 2D materials.