Fluorescent defects recently observed under ambient conditions in hexagonal boron nitride (h-BN) promise to open novel opportunities for the implementation of on-chip photonic devices that rely on identical photons from single emitters. Here we report on the room-temperature photoluminescence dynamics of individual emitters in multilayer h-BN flakes exposed to blue laser light. Comparison of optical spectra recorded at successive times reveals considerable spectral diffusion, possibly the result of slowly fluctuating, trapped-carrier-induced Stark shifts. Large spectral jumps - reaching up to 100 nm - followed by bleaching are observed in most cases upon prolonged exposure to blue light, an indication of one-directional photochemical changes possibly taking place on the flake surface. Remarkably, only a fraction of the observed emitters also fluoresce on green illumination, suggesting a more complex optical excitation dynamics than previously anticipated and raising questions on the physical nature of the crystal defect at play.
Bibliographical noteFunding Information:
H.J. and C.A.M. acknowledge support from Research Corporation via a FRED Award and from the National Science Foundation through award NSF-1545649. A.A. and M.M. acknowledge the support of the Research Council of Lithuania via Grant No. M-ERA.NET-1/2015, as well as computational resources at the High Performance Computing Center HPC Sauletekis (Physics Department, Vilnius University). Z.S., C.R.C., and V.M.M. acknowldege support from NSF through the EFRI-2-DARE program (EFMA - 1542863). J.W. and H.F. thank the German Science Foundation (DFG) and Max Planck Society. V.M.M. and C.A.M. acknowledge partial support from the National Science Foundation via the CREST-IDEALS Grant NSF-1547830.
© 2016 American Chemical Society.
- hexagonal boron nitride
- optical spectroscopy
- single-photon emitters
- spectral jumps