Blue photoluminescence from continuous freestanding β-SiC/SiOxCy/Cfree nanocomposite films with polycarbosilane (PCS) precursor

Novel continuous freestanding β-SiC/SiOxCy/Cfree nanocomposite films, namely, β-SiC nano-crystals in amorphous SiOxCy and free C cluster matrix material, were fabricated by melt spinning the polycarbosilane (PCS) precursor. Effects of oxidation curing time and sintering temperatures on the photoluminescence (PL) properties of nanocomposite films were investigated. The PL spectra show two strong blue emissions at 416 nm and 435 nm, which are unchanged neither with oxygen content nor with β-SiC crystallite size. The PL intensity of the films is enhanced by increasing curing time when sintered at 1200 °C. However, a reversed trend is identified after the films were sintered at 1300 °C. Spectroscopy and microscopy studies indicate that the radiative recombination of carriers is ascribed to the oxygen mono- and di-vacancy from SiOxCy at the surfaces of β-SiC nano-crystals, whereas the photogeneration of carriers occurs in the β-SiC nano-crystals cores. The obtained results are expected to have important applications in advanced optoelectronic devices.

Research highlights
► β-SiC/SiOxCy/Cfree nanocomposite films with different curing time were synthesized.
► The PL spectra show two blue emissions at 416 nm and 435 nm.
► PL intensity of the films sintered at 1200 °C is enhanced by increasing curing time.
► The g-factor value is attributed to unpaired electron trapped on oxygen vacancy site.
► Radiative recombination of carriers is ascribed to the oxygen mono- and di-vacancy.