Acoustic surface wave devices |
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| 申请号 | US3739290D | 申请日 | 1972-05-02 | 公开(公告)号 | US3739290A | 公开(公告)日 | 1973-06-12 |
| 申请人 | SECR DEFENCE; | 发明人 | MARSHALL F; PAIGE E; | ||||
| 摘要 | Acoustic surface wave amplifier devices wherein a coupler comprising at least several spaced filamentary conductors formed over a surface across the path of acoustic surface waves, is used to couple the acoustic surface waves to a semiconductor body mounted in close proximity to but electrically insulated from the filamentary conductors so that an electron drift established in the semiconductor body will amplify the acoustic surface waves. The semiconductor body may be mounted alongside a substrate in which the acoustic surface waves are propagated, or over the path of the acoustic surface waves, or over part of the substrate adjacent to the path of the acoustic surface waves. The part of the coupler under the semiconductor body may be isolated from the substrate by a pad of non-piezoelectric material or by the semiconductor body. | ||||||
| 权利要求 | 1. An acoustic surface wave amplifier comprising a surface formed on an elastic material capable of propagating acoustic surface waves along the said surface, acoustic surface wave coupling means comprising at least several spaced filamentary conductors formed over the said surface for causing interaction between acoustic surface waves propagated along the said surface across the filamentary conductors and electrical signals induced on the said conductors, semiconductor material mounted in close proximity to but electrically insulated from the said filamentary conductors, and means for establishing an electron drift, of velocity greater than the velocity of the acoustic surface waves, in the semiconductor material across the direction of the filamentary conductors, so that acoustic surface waves propagating along the said surface orthogonally to the filamentary conductors will be amplified. 2. An acoustic surface wave amplifier as claimed in claim 1 wherein the said elastic material is a piezo-electric material. 3. An acoustic surface wave amplifier as claimed in claim 1, formed on a non-piezoelectric substrate able to support acoustic surface waves, having a deposit of the said elastic material over a region where the said interaction is required. 4. An acoustic surface wave amplifier as claimed in claim 1, wherein the said semiconductor material is disposed adjacent to the said elastic material and has a surface substantially co-planar with the surface of the elastic material along which the acoustic surface waves will be propagated, and the said filamentary conductors of the coupling means are formed over both surfaces. 5. An acoustic surface wave amplifier as claimed in claim 4, comprising a plurality of regions of semiconductor material adjacent to the said elastic material, disposed alternately on opposite sides of the elastic material, each having a coupling means comprising filamentary conductors extending over the elastic material for interacting with acoustic surface waves therein and extending over but electrically insulated from the semiconductor material, and means for establishing an electron drift across the filamentary conductors in each region of semiconductor material, of velocity greater than the velocity of the acoustic surface waves. 6. An acoustic surface wave amplifier as claimed in claim 3, formed on a sapphire substrate having a layer of piezoelectric aluminum nitride formed over or under a part of the coupling means in the track of the acoustic surface waves, wherein the said semiconductor material is a layer of silicon formed on the sapphire over or under a part of the coupling means adjacent to the track of the acoustic surface waves. 7. An acoustic surface wave amplifier as claimed in claim 1 wherein a thin film of electrically insulating material is formed over the filamentary conductors and the said semiconductor material is formed as a thin layer over the said thin film. 8. An acoustic surface wave amplifier as claimed in claim 1, wherein parts of the coupling means, not over the track of the acoustic surface waves which are to be amplified, are formed over a layer of non-piezoelectric material of comparatively low dielectric constant. 9. An acoustic surface wave amplifier as claimed in claim 1, wherein the track of the acoustic surface waves to be amplified extends over more than half the area of the coupling means. |
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