Defect and nano-crystallite photoluminescence in Si-SiO_x systems

In this paper the room temperature photoluminescence (PL) and its temperature dependence in 80-300 K range have been investigated for magnetron co-sputtered Si-rich-SiO_x systems with Si nanocrystallites. It is shown that PL spectra consist of the five PL bands peaked at 1.32-1.39, 1.42-1.58, 1.70-1.80, 2.05 and 2.30 eV. The PL band with peak at 1.42-1.58 eV is attributed to exciton recombination in Si nanocrystallites. It was shown the well enough correlation between theoretical estimation and experimental data for exciton transition energies in Si nanocrystallites with the sizes of 3.5-5.0 nm. For smaller Si nanocrystallites (2.5 nm) the difference between experimental and calculated values of exciton transition energy is noticeable. The three visible bands are assigned to oxide related defects.