| 摘要 |
In an electret element 100 including a substrate 101, an electrically-conductive electrode 103, and an electret layer 107 including a first dielectric layer 104 and a second dielectric layer 105, when electrical charge charged in the electret layer 107 is negative, a bottom Ec of conductive band of the second dielectric layer 105 is lower than a bottom Ec of the first dielectric layer 104, and when the electrical charge is positive, a top Ev of valence band of the second dielectric layer 105 is higher than a top Ev of the first dielectric layer 104; and a concave portion 106 is formed in a surface of the first dielectric layer 104; and the second dielectric layer 105 is formed to cover the entire of the bottom face 106a and at least a part of the side wall 106b of the concave portion. |
