Paramagnetic defects related to photoluminescence in SiOx films

Abstract

The correlation between the photoluminescence and paramagnetic defects is studied in SiOx films grown by vacuum thermal deposition and annealed at 750 ⁰C. The as-grown samples exhibit a wide structureless EPR line centered at g = 2.0040, which is explained by the presence of a variety of dangling bonds •Si = SiyO₃–y. The annealing at 750 ⁰C causes the formation of amorphous silicon inclusions in SiOx matrix, appearance of the photoluminescence peaked at ~ 1.8 eV and shift of the EPR line to the low field range. The latter implies the preferable annealing of the paramagnetic defects in the regions of the sample with higher concentration of oxygen. The optically detected magnetic resonance studies show that these defects are not responsible for the luminescence; they are the centers of nonradiative recombination, but the efficiency of photoluminescence quenching due to these defects is rather low.