Abstract:
SiyO1−y :H y=0.36 and 0.42 alloy films were fabricated by electron cyclotron resonance plasma
enhanced chemical vapor deposition and subsequently annealed in Ar+5%H2 at different
temperatures. Glancing angle x-ray diffraction and Fourier transform infrared spectroscopy
measurements revealed the formation of silicon nanoclusters Si-ncl in an amorphous SiO2 matrix
for films annealed at temperatures of 900 °C and above. Negligible photoluminescence PL was
observed at room temperature for the as-grown samples; however, PL bands appeared in the visible
after the annealing treatments. The PL intensities are much higher and the spectra skewed to the red
as compared to data obtained for similar samples annealed in pure Ar. These effects are attributed
to the passivation by H atoms of nonradiative recombination centers in the materials annealed in
Ar+5%H2. The overall analysis of the PL data indicates that both quantum confinement and
defect states contribute to the luminescence. Two-step annealing procedures in Ar and then in
Ar+5%H2 were found to yield slightly higher passivation efficiencies than single annealing steps
in Ar+5%H2.
