Preparation of the Bilayer Film Electret of SiO₂ Matrix Amorphous Composite

Through the fusing and the thermal oxidation technology, the bilayer compound film (SiO₂-PbO-Al₂O₃)/SiO₂ electret was successfully prepared on the single crystalline silicon substrate. Experiments indicated that this co-mixture laminated-layer compound film possessed unique excellent electret properties. Without any chemical modification, the surface electric potential of the sample could get the equal value of the grid voltage after corona charging and decayed no more than 5% in 270d. Moreover, not only did the samples have the excellent capability of negative charges injection and storage, but also did they have the outstanding positive ones. Thermally stimulated discharge current spectra showed that the compound film had unique, single but stable charge-trapped mechanism corresponding to T = 290°C positive/negative discharge current peak, which could be attributed to its special inner microstructure.