Air-stable full-visible-spectrum emission from silicon nanocrystals synthesized by an all-gas-phase plasma approach

A novel dual-plasma system has been developed to combine the synthesis of silicon nanocrystals (Si-NCs), the etching to controllably tailor the Si-NC size, and the surface functionalization of Si-NCs into one simple all-gas-phase process. Si-NCs are synthesized in SiH₄-based plasma; they then travel through CF₄-based plasma, where Si-NCs are etched and passivated by C and F. The resulting Si-NCs exhibit air-stable emission across the full visible spectrum. Structural and optical characterization indicates that the emission in the red-to-green range is based on the recombination of quantum-confined excitons in Si-NCs, while the blue emission originates from defect states. The quantum yields of stabilized photoluminescence from Si-NCs range from 16% at the red end to 1% at the blue end.