The information of band structure of silicon nanocrystal (nc-Si) embedded in SiO2 thin films synthesized by Si ion implantation and subsequent thermal annealing at various temperatures has been obtained from spectroscopy ellipsometric (SE) analysis. The indirect band structure
and the energy gap of the nc-Si are not affected by the annealing. In contrast, the photoluminescence (PL) spectra show a continuous evolution with the annealing. Six PL bands located at 415, 460, 520, 630, 760, and 845 nm, respectively, have been observed depending on the annealing temperature.
The annealing at 1100 °C yields the strongest PL band at 760 nm (∼1.63 eV) with the intensity much higher than that of all the other PL bands. Based on the knowledge of the band structure, the 760 nm-PL band could be attributed to the indirect band-to-band transition of the nc-Si assisted
by the Si—O vibration of the nc-Si/SiO2 interface with the stretching frequency of ∼1083 cm−1 (&sim0.13 eV). On the other hand, the first four PL bands mentioned above could originate from different extended defects in the oxide matrix, while the 845-nm
PL band could be related to the interface luminescent centers.
Creation of pure non-crystalline diamond nanostructures via room temperature ion irradiation and subsequent thermal annealing