Single-photon emitters (SPEs) are essential in photonic quantum technologies, where quantum states of photons can be employed for information processing and transmission. Hexagonal boron nitride (hBN) is emerging as a promising two-dimensional (2D) material that can host bright, room-temperature SPEs. Such 2D platform benefits from high efficiency of light emission, versatile manipulation methods, and easy integration with on-chip photonics. Emitting defects in hBN exhibit a wide range of emission energies, but identifying the properties and origins of specific emitters remains challenging, which is confounded by the exponential scaling of potential candidates with the number of lattice atoms removed. To address this challenge, we collect more than 2000 spectra consisting of single, isolated zero-phonon lines in the visible range, and observe that most are organized into 7 quantized emission energies. We then characterize two new chemical processing schemes based on water and boric acid etching that generate or interconvert specific emitters, respectively. The identification and chemical interconversion of these discretized emitters should significantly advance our understanding of the solid-state chemistry and photophysics of hBN defects.<br/><br/>The promise of utilizing hBN emitters for practical applications can be seriously limited by commonly observed photobleaching. We present a systematic study comparing time-dependent 2 eV luminescence in diverse hBN samples. We further colocalize the photobleaching experiment with scanning transmission electron microscopy, and present a rich variety of atomic-scale defect structures in hBN with unprecedented crystallographic details. We find that monolayer emitters bleach quickly under continuous laser irradiation, which is dominated by photochemical reactions with oxygen in the air. We observe a second, slower bleaching process, independent of the external environment, which is likely due to carbon-assisted defect migration. Our findings reveal a key to photostable luminescence in hBN, and provide new insight into the structural origins of hBN quantum emission.

Defect engineering in hexagonal boron nitride for quantum photonics

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.