Superlattice piezoelectric devices

• US 4,590,399 A
• Filed: 10/09/1984
• Issued: 05/20/1986
• Est. Priority Date: 02/28/1984
• Status: Expired due to Term

• Current Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Roxlo, Charles B., Persans, Peter D.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US06/659,172
• Time in Patent Office: 588 Days
• Field of Search: 310/334-337, 310/800, 310/311, 310/358, 310/359, 357/4, 357/16
• US Class Current: 310/334
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure
• CPC Class Codes: H10N 30/853 Ceramic compositions
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

Piezoelectric transducers and oscillators made from amorphous superlattice structures are disclosed. These materials have large built-in fields necessary for piezoelectricity but they are materials which can be deposited at low temperatures onto virtually any substrate.

Claims

1. A piezoelectric device whose active material which exhibits the piezoelectric effect comprises a superlattice which includes a multilayered material wherein layers 1, 3, 5 . . . have the same compressibility and layers 2, 4, 6 . . . have the same compressibility but different from that of layers 1, 3, 5 . . . and wherein electric fields exist across each layer, said electric fields being perpendicular to the interface between layers with the sign of the electric field alternating between adjacent layers.

2. The piezoelectric device of claim 1 whose active material which exhibits the piezoelectric effect comprises a superlattice which includes a multilayered material where a lattice mismatch exists between adjacent layers.

3. The device of claim 1 wherein said superlattice is amorphous.

4. The device of claim 2 wherein said superlattice is amorphous.

5. The device of claim 3 wherein the electric fields are greater than 10⁴ volts/cm.

6. The device of claim 4 wherein the lattice mismatch is greater than 1 part in 10³.

7. The piezoelectric device whose active material which exhibits the piezoelectric effect comprises an amorphous superlattice wherein charge is assymetrically distributed at the interfaces thereby causing electrical fields between adjacent layers of said superlattice.

8. The device of claim 7 wherein said charge is within 20 Å

of said interfaces.

9. The device of claim 7 wherein said charge is greater than 10¹² electrons/cm².

10. A piezoelectric device whose active material which exhibits the piezoelectric effect comprises an amorphous superlattice which includes a multilayered material wherein electric fields exist across each layer, said electric fields being perpendicular to the interface between layers with the sign of the electric field alternating between adjacent layers, wherein said superlattice includes layers of a-Si:

H/a-SiN_x ;

H or layers of a-Si;

H/a-SiC_x ;

H.

11. A piezoelectric device whose active material which exhibits the piezoelectric effect comprises an amorphous superlattice which includes a multilayered material where a lattice mismatch exists between adjacent layers, wherein said superlattice includes layers of a-Si:

H/a-SiN_x ;

H or layers of a-SiH/a-SiC_x ;

H.