Comparative Investigation of Structural and Optical Properties of Si-Rich Oxide Films Fabricated by Magnetron Sputtering
Résumé
RF magnetron sputtering of two separate silicon and oxide (SiO2 or Al2O3) targets in pure
argon plasma was used for deposition of Six(SiO2)1-x and Six(Al2O3)1-x films with x=0.15-0.7 on
long fused quarts substrate. The effect of post-fabrication treatments on structural and light emitting
properties 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 both
types of films. The annealing treatment at 1150°C during 30 min results in formation of Si
nanocrystallites (Si-ncs). The latter were found to be larger in Six(Al2O3)1-x films than that in
Six(SiO2)1-x counterparts with the same x values and are under tensile stresses. The investigation of
photoluminescence properties of annealed films of both types revealed the appearance of visiblenear
infrared light emission. The Six(SiO2)1-x films demonstrated one broad PL band which peak
position shifts gradually to from 1.4 eV to 1.8 eV with the x decrease. Contrary to this, for the
Six(Al2O3)1-x films two overlapped PL bands were observed in the 1.4-2.4 eV spectral range with
peak positions at ~2.1 eV and ~1.7 eV accompanied by near-infrared tail. Comparative analysis of
PL spectra of both types’ samples showed that the main contribution to PL spectra of Six(SiO2)1-x
films is given by exciton recombination in the Si-ncs whereas PL emission of Six(Al2O3)1-x films is
caused mainly by carrier recombination either via defects in matrix or via electron states at the Sincs/
matrix interface.