Thermal Modification of a-SiC:H Films Deposited by Plasma Enhanced Chemical Vapour Deposition from CH₄+SiH₄ Mixtures

The effects of thermal annealing on photoluminescence (PL) and structural properties of a-Si_1-xC_x:H films deposited by plasma enhanced chemical vapour deposition from CH₄+SiH₄ mixtures are studied by using infrared, PL and transmittance-reflectance spectra. In a-SiC:H network, high-temperature annealing gives rise to the effusion of hydrogen from strongly bonded hydrogen in SiH, SiH₂, (SiH₂)n, SiCHn and CHn configurations and the break of weak C-C, Si-Si and C-Si bonds. A structural rearrangement will occur, which causes a significant correlation of the position and intensity of the PL signal with the annealing temperature.The redshift of the PL peak is related to the destruction of the confining power of barriers.However, the PL intensity does not have a significant correlation with the annealing temperature for a C-rich a-SiC:H network, which refers to the formation of π-bond cluster as increasing carbon content. It is indicated that the thermal stability of C-rich a-Si_1-xC_x:H films is better than that of Si-like a-Si_1-xC_x:H films.