Abstract
Electron spin resonance (ESR) spectra are investigated in order to analyze paramagnetic defects in amorphous SiO
x
films with 0.8
≤
x
≤
1.87 prepared by a co-sputtering of Si-wafer chips and a SiO
2 disk target. Effects of the thermal annealing at 900
°C and 1100
°C on the ESR spectra are also investigated. Four types of silicon dangling bond centers with forms of •Si
≡
Si
3
−
n
O
n
(
n
=
0, 1, 2 or 3) are assumed in order to simulate the ESR spectra. The random bonding model appears to describe the network structure of the films with
x
~
2, that is, near the stochiometric composition of SiO
2. It is suggested that the structural fluctuation around silicon dangling bonds is larger in the sputtered SiO
x
films used in the present work in comparison with those prepared by plasma-enhanced chemical vapor deposition.
►The ESR spectra of as-deposited SiO
x
films depend on
x. ►SiO
x
film structure follows RMM over a compositional range of
x
=
1.1–1.8. ►The ESR spectra are also affected by thermal annealing. ►Annealed SiO
x
structure is followed by ESR in connection with PL and IR results. ►Substoichiometric SiO
x
suffers a thermal decomposition after annealing at 1100
°C.