Single Photon Emitters in Ultra-Thin Hexagonal Boron Nitride Layers

TL;DR

This study demonstrates the creation and stabilization of single-photon emitters in ultra-thin hexagonal boron nitride layers, enabling potential quantum sensing applications with nanometer-scale resolution.

Contribution

It reports the activation of SPEs in 3 nm thick h-BN via electron beam irradiation and their enhancement through encapsulation, advancing ultra-thin quantum emitter integration.

Findings

SPEs activated in 3 nm thick h-BN by electron beam irradiation.

Encapsulation restores brightness and narrows linewidth at 5K.

Room temperature single-photon emission confirmed with g^{(2)}(0) < 0.4.

Abstract

Single-photon emitters (SPE) in hexagonal boron nitride (h-BN) are promising for applications ranging from single-photon sources to quantum sensors. Previous studies exclusively focused on the generation and characterization of SPEs in relatively thick h-BN layers ($\geq$ 30 nm). However, for electrical and magnetic sensing applications, the thickness of the h-BN limits the attainable spatial resolution. Here, we report the observation of blue-wavelength emitters (B-centers) activated by electron beam irradiation in ultra-thin ($\simeq$ 3 nm) h-BN. These SPEs in ultra-thin flakes exhibit reduced brightness, broader zero-phonon line, and enhanced photobleaching. Remarkably, upon encapsulation in thicker h-BN, we restore their brightness, narrow linewidth 230$\mu$eV at 5K, resolution limited), suppress photobleaching, and confirm single-photon emission with $ g^{(2)}(0) < 0.4$ at room temperature. The possibility of generating SPEs in a few-layer h-BN and their subsequent incorporation into a van der Waals heterostructure paves the way for achieving quantum sensing with unprecedented nanometer-scale spatial resolution.