Comparative Investigation of Structural and Optical Properties of Si-Rich Oxide Films Fabricated by Magnetron Sputtering

International audienceRF magnetron sputtering of two separate silicon and oxide (SiO2 or Al2O3) targets in pureargon plasma was used for deposition of Six(SiO2)1-x and Six(Al2O3)1-x films with x=0.15-0.7 onlong fused quarts substrate. The effect of post-fabrication treatments on structural and light emittingproperties of the films with different x values was investigated by means of Raman scattering,electron paramagnetic resonance and X-ray diffraction as well as by photoluminescence (PL)methods. The formation of amorphous Si clusters upon deposition process was found for the bothtypes of films. The annealing treatment at 1150°C during 30 min results in formation of Sinanocrystallites (Si-ncs). The latter were found to be larger in Six(Al2O3)1-x films than that inSix(SiO2)1-x counterparts with the same x values and are under tensile stresses. The investigation ofphotoluminescence properties of annealed films of both types revealed the appearance of visiblenearinfrared light emission. The Six(SiO2)1-x films demonstrated one broad PL band which peakposition shifts gradually to from 1.4 eV to 1.8 eV with the x decrease. Contrary to this, for theSix(Al2O3)1-x films two overlapped PL bands were observed in the 1.4-2.4 eV spectral range withpeak positions at ~2.1 eV and ~1.7 eV accompanied by near-infrared tail. Comparative analysis ofPL spectra of both types’ samples showed that the main contribution to PL spectra of Six(SiO2)1-xfilms is given by exciton recombination in the Si-ncs whereas PL emission of Six(Al2O3)1-x films iscaused mainly by carrier recombination either via defects in matrix or via electron states at the Sincs/matrix interface