Browse Prior Art Database

Detection of Piezoelectric Surface Acoustic Waves

IP.com Disclosure Number: IPCOM000091061D
Original Publication Date: 1969-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Powell, CG: AUTHOR [+2]

Abstract

Piezoelectric acoustic surface waves are detected by plane surface insulated-gate field-effect transistors IGFET's. External electric fields associated with a propagating piezoelectric acoustic surface wave are used to control the resistance channels between the source and the drain in a IGFET. Thus the output current of the IGFET is modulated.

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Detection of Piezoelectric Surface Acoustic Waves

Piezoelectric acoustic surface waves are detected by plane surface insulated-gate field-effect transistors IGFET's. External electric fields associated with a propagating piezoelectric acoustic surface wave are used to control the resistance channels between the source and the drain in a IGFET. Thus the output current of the IGFET is modulated.

The IGFET device shown consists only of a P-type substrate 10 on which are diffused two separated n/+/ regions 12 and 14 as the source and drain connections. The oxide layer and the metal pattern of a usual IGFET device are removed. The optical polished IGFET surface is then laid in the path of surface acoustic waves. These are caused to propagate in piezoelectric substrate 16 by transducer 18. The width of the acoustic beam has to be larger than the separation between source 12 and drain 14.

As the propagating piezoelectric acoustic surface waves reach the IGFET region, the external electric fields associated with the surface waves redistribute the minority carriers in substrate 10 and create resistance channels between regions 12 and 14. If the surface acoustic waves are sinusoidal, the associated electric fields have alternate polarities in the direction of propagation. This IGFET can operate in type C mode which is a normally-off device. As the sinusoidal acoustic surface waves register under the IGFET, n channels of the resistant channel between regions 12 and 14 make...