Synthesis and single photon emission characterization of carbon-doped hexagonal boron nitride grown on Silicon Carbide substrates

Single-photon emitters play a crucial role in the advancing fields of quantum communication, quantum computing, and integrated quantum photonics. In particular, hexagonal boron nitride (hBN) stands out as a promising material due to its wide bandgap, enabling it to support a diverse array of emitters across the visible to ultraviolet spectrum while maintaining stability at room temperature. These emitters arise from spatially isolated defects which introduce mid-gap states which can be excited and act as emitting color centers. However, the exact nature of these defects is not yet fully elucidated and different classes of defects have been studied.

In this work, we present a novel method of synthesizing mono- and few-layer hBN on silicon carbide, capable of emitting single photons in a narrow emission wavelength range. The hBN was synthesized using a high temperature induction furnace. In particular, boricBoric acid was spin coated on 6H-SiC to provide and heated at 1800 C in a nitrogen atmosphere, yielding a uniform film of hBN. The synthesized hBN material was confirmed by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy. electron microscopy and reflective electron energy loss spectroscopy.

The emitters in this hBN material are active at room temperature and exhibit a narrow emission centered at 625 nm. To identify the source of these defects, we characterized the sample using XPS and UV-Raman spectroscopy, which revealed a strong correlation between the emissions and carbon-related defects. Theoretical predictions further supported that the narrow emission wavelength range arises from a carbon-rich hBN structures. Antibunching measurements performed using a Hanbury Brown-Twiss interferometer confirmed that these emitters are single-photon sources, with g²(0) < 0.5. This study strengthens the evidence that visible-range single photon emitters in hBN are attributed to carbon substitution defects.