Fabrication of silicon carbide color center nanoparticles by femtosecond laser ablation in liquid

Combined with the fabrication of low-dimensional materials, certain silicon carbide color centers can become excellent platforms for nano-optics, and be applied to quantum and biomedical fields. In this work, color center nanoparticles were prepared based on high purity semi-insulating silicon carbide substrate using liquid-assisted femtosecond laser machining. Effects of multi-pulse array ablation and line scanning fabrication were investigated, and parameters such as repetition frequency and pulse number were also optimized. We employed photoluminescence spectroscopy, field emission scanning electron microscopy and transient fluorescence spectroscopy to characterize optical properties and micromorphology of nanoparticles. The broadband photoluminescence within the range of 850–950 nm should be attributed to silicon vacancy color centers, and V1/V1’ zero-phonon lines were confirmed at low temperature. It is noted that the femtosecond laser annealing is critical for the luminescence enhancement of color center nanoparticles. The evolution of particles and cavitation bubbles during processing was elucidated. After optimization, silicon vacancy color center nanoparticles were prepared by multi-pulse (10⁷) array ablation and 200 kHz pulse repetition frequency, with an average diameter of approximately 15 nm and an average density reaching 273.94 counts/μm². The sample can be preserved stably in the form of nanoparticle solutions. Processing methods and corresponding conclusions of this study would be applicable to the femtosecond laser fabrication and micromorphology control of color center nanoparticles of various hard-brittle semiconductors.