Fabrication and analysis of electret back-plates in microphones

This paper shows some technique about fabrication and analysis of electret back-plates in a kind of special microphones, which are used in measurement of sound wave. The sample of Teflon-FEP film (25 um thick) is deposited on the surface of the back-electrode of metal. Based on experimental results of the surface potential decay of electret samples, we use the method of high temperature extrapolation to calculate the active energy of trapped electrons. The result of experiments of surface potential decay is coincident with the theoretical analysis.