| abstract |
An electret device. The device has a thickness of substrate material having a contact region. An electrically floating conducting region is formed overlying the thickness of substrate material. The floating conducting region is free from physical contact with the contact region. A protective layer is formed overlying the floating conductive layer. The protective layer has a surface region and seals the floating conducting region. The thickness of substrate material, floating conducting region, and protective layer form a sandwiched structure having a charge density of at least 1×10−4 Coulombs/m2 and a peak to peak charge uniformity of 5% and less. |