Microstructure Evolution Induced by Ultraviolet Light Irradiation in Ti-Si Codoped Diamond-like Carbon films

Titanium/silicon co-doped diamond-like carbon films were deposited on Si substrate by middle frequency magnetron sputtering using Ti80Si20 composite as target. The microstructure of the deposited films was characterized by ultraviolet and visible multi-wavelength Raman spectroscope. The influence of ultraviolet light irradiation on microstructure of the films was investigated by a combination of Raman and FTIR spectroscope. The mechanism of microstructural evolution of the films induced by ultraviolet light irradiation was discussed. The results show that the film dominated by amorphous structure displays inclusions of trans-polyacetylene, p-phenylene vinylene and sp hybridized carbine carbon chains. Ultraviolet light irradiation induces the relaxation and reconstruction of microstructure in the films, which leads to the increase of Si–O and C–O bonding, and the decrease of C=C and C–H bonding. Meanwhile, the size of sp clusters in the films decreases and the degree of disorder of sp clusters increases.