Effects of high-temperature annealing on electron spin resonance in SiOx films prepared by R. F. sputtering system

Electron spin resonance (ESR) spectra are investigated in order to analyze paramagnetic defects in amorphous SiOx films with 0.8 ≤ x ≤ 1.87 prepared by a co-sputtering of Si-wafer chips and a SiO2 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 ≡ Si3 − nOn (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 SiO2. It is suggested that the structural fluctuation around silicon dangling bonds is larger in the sputtered SiOx films used in the present work in comparison with those prepared by plasma-enhanced chemical vapor deposition.

Research Highlights
► The ESR spectra of as-deposited SiOx films depend on x.
► SiOx film structure follows RMM over a compositional range of x = 1.1–1.8.
► The ESR spectra are also affected by thermal annealing.
► Annealed SiOx structure is followed by ESR in connection with PL and IR results.
► Substoichiometric SiOx suffers a thermal decomposition after annealing at 1100 °C.