Optical properties of low‐defect large‐area h–BN for quantum applications

Intrinsic defects and their concentrations in hexagonal boron nitride play a key role in single photon emission. This study explores the optical properties of large‐area multilayer h–BN‐on‐sapphire grown by metalorganic chemical vapor deposition. Based on our detailed spectroscopic characterization using both cathodoluminescence and photoluminescence measurements, the material is devoid of random single‐point defects instead of a few clustered complex defects. The emission spectra of the measurements confirm a record‐low defect concentration of ∽104 cm‐2. Post‐annealing, no significant changes are observed in the measured spectra and the defect concentrations remain unaltered. Through cathodoluminescence and photoluminescence spectroscopy, we identify an optically active boron vacancy spin defect and reveal a novel complex defect combination arising from carbon impurities. This complex defect, previously unreported, signifies a unique aspect of our material. Our findings contribute to the understanding of defect‐induced optical properties in h–BN films, providing insights for potential applications in quantum information science.This article is protected by copyright. All rights reserved.