An Epr Investigation of Siox Films with Columnar Structure

The results of electron paramagnetic resonance (EPR) study of obliquely deposited porous SiOx 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 0.77mT has been detected in as-sputtered films and attributed to dangling bonds of silicon atoms in amorphous SiOx 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 0.11mT and a hyperfine doublet with 1.6mT 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 SiO2. The impact of chemical treatment before annealing and duration of anneals on the defect system is discussed.