Effect of thermal annealing on the blue luminescence of amorphous silicon oxycarbide films

•Luminescent a-SiCxOy films were prepared at a low temperature of 250 °C.•The blue PL intensity can be significantly enhanced by thermal annealing.•The intense light emissions can be observed with the naked eye in a bright room.•The blue PL of a-SiCxOy films is ascribed to the Si-related NOV defect centers.

Amorphous silicon oxycarbide (a-SiCxOy) films that displayed blue luminescence were fabricated using very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) at a temperature of 250 °C. The effects of thermal annealing on the photoluminescence (PL) were investigated. Thermal annealing at 600 °C resulted in a remarkable enhancement in the blue PL, which was clearly observed with the naked eyes in a bright room. The blue PL featured an excitation wavelength independent recombination dynamic on a nanosecond timescale. Neither Si nor SiC quantum dots were present in the annealed films as revealed by transmission electron microscopy. The PL results, combined with an analysis of the chemical bonds present in the films, revealed that the origin of the blue PL was largely due to electron–hole pair recombination through Si-related neutral oxygen vacancy defect centers.