Hierarchical microstructure growth in a precursor‐derived SiOC thin film prepared on silicon substrate

Silicon oxycarbide film deposited on a silicon substrate has shown superior electrical conductivity relative to its monolithic counterpart. In this work, the evolution of different microstructures detected on the SiOC film reveals its hierarchical microstructure. The existence of sp²‐hybridized carbon domains has been unambiguously confirmed by means of Raman spectroscopy and transmission electron microscopy corroborated with electron energy loss spectroscopy. The diffusion coefficient of carbon in silica and its dependence on temperature were studied by assessing energy‐dispersive X‐ray spectroscopy profiles taken from the cross‐sections of samples annealed at temperatures in the range from 1100°C to 1400°C. The activation energy for diffusion of carbon in silica was determined to be approximately 3.05 eV, which is significantly lower than the values related to the self‐diffusion of silicon and oxygen. The microstructural evolution of precursor to SiCnO₄-n and SiC serves as migration path of sp²‐hybridized carbon to the SiOₓ layer. With increasing temperature, the formation of microscale carbon‐rich segregation is promoted while the SiOC film becomes thinner.