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US 10,833,607 B2Granted
Electret element, electromechanical converter and method for manufacturing electret element
AssigneesThe University of Tokyo, Kabushiki Kaisha Saginomiya Seisakusho
InventorsHiroyuki Fujita, Gen Hashiguchi, Hisayuki Ashizawa, Hiroyuki Mitsuya, Kazunori Ishibashi
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Abstract
An electret element includes: an Si layer, an SiO2 layer formed at a surface of the Si layer; and an electret formed at the SiO2 layer near an interface of the SiO2 layer and the Si layer.
Claims8
An electret element, comprising:
- an Si layer,
- an SiO2 layer formed at a surface of the Si layer;
- and
- an electret formed at the SiO2 layer near an interface of the SiO2 layer and the Si layer,
- wherein a negative charge constituting the electret is fixed in the SiO2 layer near the interface of the SiO2 layer and the Si layer,
- wherein a positive charge is accumulated in the Si layer near the interface of the SiO2 layer and the Si layer,
- wherein an electric double layer formed with the negative charge and the positive charge is formed entirely through the interface of the SiO2 layer and the Si layer so that no electric field is allowed to extend beyond the electric double layer, and
- wherein there is no electric charge near a surface of the SiO2 layer which is opposite the interface of the SiO2 layer and the Si layer.
5 more elements
A method for manufacturing an electret element, comprising:
- applying a voltage between an Si layer, with an SiO2 layer formed thereat, and the SiO2 layer while sustaining the Si layer at a first temperature at which the SiO2 layer is rendered in a semiconductor state;
- and
- changing temperatures at the Si layer with the SiO2 layer formed thereat from the first temperature to a second temperature at which the SiO2 layer regains an insulating property in a state of continuous voltage application,
- wherein an electret is formed at the SiO2 layer near an interface of the SiO2 layer and the Si layer,
- a negative charge constituting the electret is fixed in the SiO2 layer near the interface of the SiO2 layer and the Si layer,
- a positive charge is accumulated in the Si layer near the interface of the SiO2 layer and the Si layer, and
- an electric double layer formed with the negative charge and the positive charge is formed entirely through the interface of the SiO2 layer and the Si layer so that no electric field is allowed to extend beyond the electric double layer, and
- wherein there is no electric charge near a surface of the SiO2 layer which is opposite the interface of the SiO2 layer and the Si layer.
5 more elements
Dependencies are inferred from the claim text.