Photoluminescence in hexagonal silicon carbide by direct femtosecond laser writing.

Direct femtosecond laser writing has been used to produce localized regions of photo-luminescent emission in 4H- and 6H-silicon carbide (SiC). Arrays of active color centers were fabricated by different pulse laser energies in the sites of square grids at various depths (from surface level to 10 µm below surface). We optically characterized the fabricated color centers using confocal imaging with 532 and 780 nm excitation, photo-luminescence spectroscopy, and lifetime decay at room temperature. We show that the technique can produce specifically the silicon vacancy color center emitting in the range 850-950 nm and other emitters in the 700 nm. This method can be adopted to engineer color centers in (SiC) at different depths in the material for single-photon generation, sensing, display fabrication, and light emitting diodes.

Fluorescent color centers in laser ablated 4H-SiC nanoparticles.

Nanostructured and bulk silicon carbide (SiC) has recently emerged as a novel platform for quantum nanophotonics due to its harboring of paramagnetic color centers, having immediate applications as a single photon source and spin optical probes. Here, using ultra-short pulsed laser ablation, we fabricated from electron irradiated bulk 4H-SiC, 40-50 nm diameter SiC nanoparticles, fluorescent at 850-950 nm. This photoluminescence is attributed to the silicon vacancy color centers. We demonstrate that the original silicon vacancy color centers from the target sample were retained in the final nanoparticles solution, exhibiting excellent colloidal stability in water over several months. Our work is relevant for quantum nanophotonics, magnetic sensing, and biomedical imaging applications.