Divacancy spin defects coupled to photonic crystal cavities in 4H-SiC

Silicon carbide (SiC) has recently been developed as a platform for optically addressable spin defects in the form of the neutral divacancy, most notably in the 4H polytype [1-3]. Here we present progress in the fabrication and characterization of 4H-SiC photonic crystal cavities coupled to neutral divacancies. We use a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities. For divacancies in the cavity mode, the Purcell effect enhances near-infrared optical emission from the defect. This results in increased photon count rates due to reduced excited state lifetimes, and for cavity wavelengths matched with the defect, the Purcell enhancement increases emission into the zero-phonon line. This enhancement has applications for the scalability of long-distance entanglement schemes that require the interference of indistinguishable photons from spatially separated defects.

[1] W. F. Koehl et al., Nature 84, 479 (2011).
[2] D. J. Christle et al., Nat. Mat. 14, 160 (2015).
[3] D. J. Christle et al., Phys. Rev. X. 7, 021046 (2017).