James Stewart1 Hannah Stern2 Jack Alexander-Webber1 Steven Lee2 Ruizhi Wang1 Vitaly Babenko1 Stephan Hofmann1

1, Engineering, University of Cambridge, Cambridge, , United Kingdom
2, Chemistry, University of Cambridge, Cambridge, , United Kingdom

Defect-induced sub-bandgap emission from hexagonal boron nitride (hBN) is not only hugely interesting for quantum technology, opening a promising route for the design of next-generation single-photon sources [1], but equally offers a new high-throughput characterisation pathway for large-area h-BN films, an urgent requirement given the recent progress in synthesising h-BN; particularly by chemical vapour deposition (CVD) [2]. We present our latest data employing multidimensional super-resolution fluorescence microscopy and other techniques to simultaneously measure spatial position, intensity, and spectral properties of the emitters in h-BN [3,4]. We specifically focus on CVD grown mono-layer h-BN samples over cm areas, which readily offers scalable device integration routes. Our data reveals a correlation in blinking and spectral diffusion for single emitters in monolayer h-BN, closely reminiscent of the behaviour observed in quantum dots [3]. We explore a range of CVD growth, transfer [2, 5] and encapsulation methods warranting controlled, clean and direct emitting-monolayer interfacing, giving us the ability to vertically place emitters with high accuracy. We report on detailed emitter statistics dependant on process conditions and how surface interactions heavily influence the photodynamics. Drawing on quantum dot literature, we devise approaches to enhance and control h-BN emitter properties. We also compare this optical characterisation with a range of other h-BN characterisation techniques to develop a holistic understanding.

[1] Vogl et al. arXiv:1902.03019 (2019).
[2] Wang, R. et al. ACS Nano 13, 2114 (2019).
[3] Stern, H. L. et al. ACS Nano 13, 4538–4547 (2019).
[4] Comtet, J. et al. Nano Lett. 19, 2516–2523 (2019).
[5] De Fazio et al. arXiv:1904.01405 (2019).