An EPR investigation of SiOx films with columnar structure

Abstract The results of electron paramagnetic resonance (EPR) study of obliquely deposited porous SiO x films before and after thermal annealing in vacuum at 950 °C are presented. The low intensity slightly asymmetrical and featureless EPR line with a g -value of 2.0044 and a linewidth of 0.77 mT has been detected in as-sputtered films and attributed to dangling bonds of silicon atoms in amorphous SiO x domains with x =0.8. Successive annealing results in decreasing this line and the appearance of an intense EPR line with g =2.0025, linewidth of 0.11 mT and a hyperfine doublet with 1.6 mT splitting. According to the parameters this spectrum has been attributed to the EX center, a hole delocalized over four non-bridging oxygen atoms grouped around a Si vacancy in SiO 2 . The impact of chemical treatment before annealing and duration of anneals on the defect system is discussed.