Selective electret charging method of SiO2 film for energy harvesters by using biased electrode

Electret materials are useful for electrostatic type energy harvesters. Since the power generated from the electret energy harvester is proportional to the surface charge concentration, i.e. charged voltage on the electret, frequency and dynamic range of the capacitance change. To fabricate the electret, the corona discharge is a very popular charging method, which consists of a high voltage needle for corona ions generation and a grid electrode applying a bias voltage that implants the electrons from corona ions to the electret material. We have established the charging method with finely patterned charging area by using the buried grid electrodes (BGE) applied with a bias voltage for organic material CYTOP. However, CYTOP has slightly poor characteristics in terms of the thermal robustness. In this study we report a fabrication technique of the selectively charged SiN/SiO2 as electret material alternative to the CYTOP. By using the BGE method to SiN/SiO2 film, a fine patterned electret with highly thermal robustness was obtained.