Optical and structural studies of silicon-enriched films obtained by dc-magnetron co-sputtering

We present in this work preliminary studies concerning the optical characterization, by optical absorption, photoluminescence and Raman spectroscopies, of Si-enriched films into a SiO2 matrix as a function of the Si concentration. The Si-molar concentration dependence shows different characteristics for each one of the samples: low Si concentration samples (lower than 50 mol% of silicon) showed, at room temperature, a low energy PL band around 1.6 eV, whereas samples with higher concentration (> 50 mol% of silicon) showed a PL band at 2.27 eV. Raman spectra of the samples account for different characteristics: low Si concentration samples showed a contribution of the amorphous phase of SiO2, whereas for high Si concentration samples, a relaxation of the selection rules is observed. Discussion and analysis of the experimental results are presented.