Variation of photoluminescence from Si nanostructures in SiO2 matrix with Si+ post implantation

Si nanoclusters were formed by 28Si ion implantation into SiO2 matrix and subsequently annealed at 1050 °C for 2 h under N2 ambient. The photoluminescence (PL) characteristics depend on the 28Si fluence. The PL signals seen at around 775 nm and 825 nm are assigned to light emitting centers connected to formation of Si clusters, for 5 × 1016 cm−2 and 1 × 1017 cm−228Si fluences, respectively. Defect-related light emission observed at around 625 nm emerges only in the case of high implantation fluence. These sample sets were post implanted with 28Si ions at fluences between 1 × 1012 and 1 × 1014 cm−2 to monitor the variations in PL emission as a function of post implantation fluence. The PL emission decreases and exhibits a blue-shift with increasing post implantation fluence and quenches totally when the fluence exceeds a certain value, while the peak seen at 625 nm which is related to matrix defects is enhanced after the post implantation. Upon thermal annealing, the PL peaks measured at 775 nm and 825 nm recovered and reached the intensity of the peak before the post implantation. The variations in the PL peak with the implantation fluence and annealing conditions are ascribed to the different structure of Si nanoinclusions in the SiO2 matrix.