Charge injection and storage in single-layer and multilayer inorganic electrets based on SiO2 and Si3N4

It is shown that the maximum surface potential in inorganic electrets is limited by the breakdown of the dielectric layer. It is observed that several composing layers contribute to charge trapping in multilayer electrets. The mean distance of charge from the substrate and the trap density are extracted. At least two dielectric layers are necessary for improving charge retention at elevated temperatures. The studied electrets are promising for applications and show a lifetime of over 10 years at a temperature of 200°C.