The application of silicon dioxide as an electret material

The authors have investigated silicon dioxide for its electret properties. It appears that thermally grown silicon dioxide has a large lateral surface conductivity, resulting in poor electret behavior. This can be adequately reduced by chemical surface modification, resulting in an excellent silicon dioxide electret. Experiments have shown that corona-charged SiO₂ layers are much more resistant to high temperatures than Teflon-FEP electrets. A 1.1-μm-thick SiO₂ layer, charged up to 150 V, yields a time constant of the charge decay in excess of 400 yr at ambient laboratory conditions