Comparative study of implanted and sputtered systems of Si nanograins embedded in SiO_2

摘要

Si nanograins embedded in silicon oxide matrix have been obtained by thermal annealing at 1100 deg C during one hour, either after implantation of Si~+ into thermal SiO_2 layers or after magnetron cosputtering of both Si and SiO_2. The spectral distribution fo the photoluminescence (PL) in both systems is similar and peaks in the red visible region (1.45-1.60 eV). The results obtained indicate that for high PL efficency , the films have to be annealed at temperatures high enough to achieve phase separation. This was observed from the gradual shift of the infrared bands of the silica matrix toward those of thermal SiO_2, together with the appearance of the crystlaline silicon Raman vibrational mode in the spectra. The similar behavior of samples obtianed by ion implantation and by sputtering suggests a more complex origin of the PL than quantum confinement.