Optically active solid-state spin qubits in heteropolytypic silicon carbide structures

Optically addressable spin qubits in wide band-gap semiconductor materials are promising candidates for future quantum technologies. One material platform that has received a great deal of attention in this pursuit is silicon carbide (SiC) due to the availability of high-quality, wafer-scale material and low nuclear spin isotope concentration, among other reasons. Furthermore, the existence of several SiC polytypes offers a unique opportunity to engineer the properties of spin qubits. It has been suggested that SiC point defects embedded in stacking faults can exhibit modified electron-phonon coupling strengths and robustness against photoionization. However, systematic studies involving stacking faults are inherently challenging, partly due to sample-to-sample variability in crystallographic defect types and densities.

Here, we demonstrate the formation of cubic phase SiC nanoinclusions in commercial 4H-SiC spanning hundreds of microns, suitable for exploring interactions between spin qubits and extended crystallographic defects. We study these inclusions using various electron microscopy techniques and report on the optical and spin properties of vacancy-based defects. Our work provides new insights into and opportunities for defect engineering in SiC.