Attribution of white-light emitting centers with carbonized surface in nano-structured SiO2:C layers

Carbon incorporated silicon oxide layers were fabricated by carbonization of porous silicon layer in acetylene atmosphere followed by oxidation in wet argon. The resulting porous SiO2:C material exhibited a strong white photoluminescence. Subsequent thermal treatment in oxygen at 600 °C significantly decreased the green–yellow part of photoluminescence band while blue shoulder remained unchanged. Annealing at the same temperature in pure argon did not change light-emission properties indicating that the green–yellow light-emission sites originate from the surface. This study focuses on the interface of silicon oxide matrix and carbon inclusions by high-resolution scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). It is confirmed by EELS and STEM that the green–yellow emission band is associated with the carbonized interface in the porous layer.