Direct writing of divacancy centers in silicon carbide by femtosecond laser irradiation and subsequent thermal annealing

Divacancy (VSiVC) centers in silicon carbide (SiC) have potential applications in quantum communication and sensing due to their attractive optical and spin properties. To realize many of these divacancy-based quantum applications, it is vital that they are created in prescribed locations with high accuracy. Here, we describe the production of arrays of divacancy centers in 4H polytype SiC (4H-SiC) by femtosecond laser irradiation and subsequent thermal annealing. We optically characterized these divacancy centers by photoluminescence (PL) confocal mapping using a custom-built confocal microscope. The created divacancy centers show a bright stable emission that depends on the pulse energy of the femtosecond laser. PL spectra of the divacancy centers were collected using micro-Raman spectroscopy at the low temperature of 4.2 K and room temperature. The effect of thermal annealing was studied at various temperatures from 500 °C to 1000 °C and showed that the maximum divacancy center PL intensity was achieved at 800 °C. These and the aforementioned measurements show that the femtosecond laser writing method enables divacancy centers to be accurately positioned in 4H-SiC.