Raman study of stress effect in silicon rich carbide (SiCX) film by furnace and rapid thermal annealing for photovoltaic application

Si nanocrystals in SiC_X films by both furnace and rapid thermal annealing (RTA) techniques have been studied by Raman characterization. Silicon rich carbide films with different stoichiometric composition were prepared by co-sputtering of Si and SiC targets. Two different annealing processes have been applied on all SiC_X amorphous samples: furnace annealing at 1100°C/1hr and RTA at 1100oC/30 sec. Peak position of Raman pattern is strongly shifted from Si reference wafer position in RTA samples (Δ =5.4cm^-1) compare with furnace samples (Δ=2cm^-1), indicating great tensile stress on Si nanocrystals. This is because of different thermal expansion coefficient of Si and SiC crystals and fast temperature ramping rate in high temperature annealing in RTA process. From further Raman analysis, we found after applying an additional furnace annealing, all samples with different Si concentration could well release residual stress. But additional RTA could only release residual stress in highest Si concentration samples due to insufficient time duration.