Robust Optically Stable Single Photon Emission from Single‐Crystal Hexagonal Boron Nitride Films

ABSTRACT Quantum emitters in hexagonal boron nitride (h‐BN) have emerged as promising candidates for integrated quantum applications due to their room‐temperature operation and compatibility with 2D platforms. However, most works have focused on exfoliated h‐BN flakes or vapor deposition‐grown h‐BN films with a variety of intrinsic defects. Herein, we demonstrate highly pure, bright, and linearly polarized single‐photon emitters (SPEs) in large‐area single‐crystal h‐BN films grown by submicron‐spacing vapor deposition method. Further, the photostability of SPEs is remarkably improved by introducing an h‐BN capping layer, which effectively isolates the emitters from environmental oxygen impurities and thus suppresses blinking and photobleaching. Specifically, the half‐life time of emitters in the protected sample increases by approximately two orders of magnitude, and the h‐BN emitters remain stable emission without any blinking or photobleaching for more than 140 min at room temperature. This work provides a promising approach for large‐scale fabrication of high‐purity, stable h‐BN based SPEs for realizing robust quantum light sources.