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 degrees 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. (C) 2011 Elsevier B.V. All rights reserved.