Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1983-02-09
1984-06-26
Budd, Mark O.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310328, 310331, 310346, H01L 4108
Patent
active
044568509
ABSTRACT:
A piezoelectric composite thin-film resonator has good temperature stability and resonance response, in a fundamental thickness-extensional vibration mode. Spurious vibrations caused by even-number order harmonic overtones are suppressed. The resonator has a thin film of SiO.sub.2 or other materials having a resonant frequency temperature coefficient which is opposite to that of the piezoelectric material. The SiO.sub.2 layer is inserted between two thin films of ZnO, CdS, AlN, or other piezoelectric materials. This sandwiched structure is positioned between a pair of electrode films and is supported by an insulative or a semiconductive film which is in turn fixed to a substrate. The thicknesses of the thin films have values such that an overall temperature coefficient of the resonant frequency may be at or near substantially zero. In order to better remove the even-number order harmonics, it is preferable to cover the upper electrode film with a thin film of semiconductor or insulator material.
REFERENCES:
patent: 2202391 (1940-05-01), Mason
patent: 3401275 (1968-09-01), Curran et al.
patent: 3437849 (1969-04-01), Treatch et al.
patent: 3486046 (1969-12-01), Zalar
patent: 3505572 (1970-04-01), Yamashita et al.
Acoustic Bulkwave Composite Resonators, by Lakin and Wang, Applied Physics Letters, vol. 38, No. 3, Feb. 1981, pp. 125-127.
Electronics Letters, Jul. 9, 1981, vol. 17, No. 14, ZnO/SiO.sub.2 -Diaphragm Composite Resonator on a Silicon Wafter, pp. 507-509.
Inoue Takeshi
Miyasaka Yoichi
Budd Mark O.
Nippon Electric Co. Ltd.
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