Exotic single-photon and enhanced deep-level emissions in hBN strain superlattice

TL;DR

This paper demonstrates how a strain superlattice in multilayer hBN can activate and enhance defect-related photon emissions, including single-photon and deep-level emissions, with potential applications in quantum nanophotonics.

Contribution

It introduces a simple on-chip method to activate and tune defect emissions in multilayer hBN using strain superlattice fabrication on silica spheres.

Findings

Effective activation of single-photon emissions at contact points with silica spheres.

Blue-shift of SPEs up to 12 nm due to local tensile strain.

Deep-level emission enhancement up to 350% with a 6 nm redshift.

Abstract

The peculiar defect-related photon emission processes in 2D hexagonal boron nitride (hBN) have become a topic of intense research due to their potential applications in quantum information and sensing technologies. Recent efforts have focused on activating and modulating the defect energy levels in hBN by methods that can be integrated on a chip, and understanding the underlying physical mechanism. Here, we report on exotic single photon and enhanced deep-level emissions in 2D hBN strain superlattice, which is fabricated by transferring multilayer hBN onto hexagonal close-packed silica spheres on silica substrate. We realize effective activation of the single photon emissions (SPEs) in the multilayer hBN at the positions that are in contact with the apex of the SiO2 spheres. At these points, the local tensile strain induced blue-shift of the SPE is found to be up to 12 nm. Furthermore, high spatial resolution cathodoluminescence measurments show remarkable strain-enhanced deep-level (DL) emissions in the multilayer hBN with the emission intensity distribution following the periodic hexagonal pattern of the strain superlattice. The maximum DL emission enhancement is up to 350% with a energy redshift of 6 nm. Our results provide a simple on-chip compatible method for activating and tuning the defect-related photon emissions in multilayer hBN, demonstrating the potential of hBN strain superlattice as a building block for future on-chip quantum nanophotonic devices.