STRESS-STRAIN TRANSDUCER CHARGE COUPLED TO A PIEZOELECTRIC MATERIAL

• US 3,585,415 A
• Filed: 10/06/1969
• Issued: 06/15/1971
• Est. Priority Date: 10/06/1969
• Status: Expired due to Term

• Current Assignee: James Conragan, Richard S. Muller
• Original Assignee: James Conragan, Richard S. Muller
• Inventors: Muller, Richard S., CONRAGAN JAMES
• Application Number:
  US04/864,058
• Time in Patent Office: 617 Days
• US Class Current: 310/319
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7849 the means being provided under the channel
• CPC Class Codes: H01L 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/78648 arranged on opposing sides of the channel
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

A piezoelectric material is connected to a semiconductor having source and drain electrodes at opposite ends thereof. The piezoelectric material is charge coupled to the semiconductor and spaces and electrically insulated the semiconductor and spaces and electrically insulates the semiconductor from a gate electrode disposed between the source and the drain. Application of a voltage to the source and drain and of a constant voltage to the gate and source causes a current flow which is a function of the stress-strain to which the piezoelectric material is subjected and can thus be employed to indicate the magnitude of such stress-strain.

Claims

2. A stress-strain transducer according to claim 1 wherein the body of piezoelectric body comprises a plurality of layers of piezoelectric and insulating materials between the semiconductor element and the gate electrode.

3. A stress-strain transducer according to claim 1 wherein the piezoelectric body comprises a substrate for the semiconductor element, and wherein the transducer further includes a second conductive gate electrode mounted to the substrate and disposed on the side of the substrate opposite frOm the semiconductor element, and means for subjecting the second gate electrode to a constant voltage.

4. A stress-strain transducer according to claim 3 wherein the semiconductor element has a thickness of the order of about 1 Debye length for the material of which the semiconductor element is constructed.

5. A stress-strain transducer according to claim 3 wherein the substrate comprises a piezoelectric ceramic material.

6. A stress-strain transducer according to claim 2 wherein the semiconductor comprises silicon, and the layers include a first silicon oxide layer contacting the semiconductor element, a layer of cadmium sulfide and a second aluminum dioxide insulating layer, and wherein the layers have an aggregate thickness permitting their full penetration by an electrostatic field generated by a DC bias on the gate electrode.

7. A stress-strain transducer according to claim 2 wherein the semiconductor element and the piezoelectric body extend past the source electrode and the drain electrode for propagating mechanical waves through the piezoelectric body and converting such waves into electrical signals.

8. A stress-strain transducer comprising a semiconductor device having conductive source and drain electrodes at opposite ends thereof, a piezoelectric material in contact with and directly charge coupled to the semiconductor device and positioned adjacent a semiconductor device channel between the electrodes, a gate electrode mounted to the piezoelectric material, electrically insulated from the semiconductor device by the piezoelectric material and positioned on the side of the piezoelectric material opposite the channel, and means for applying a constant electric potential to the gate electrode, whereby the application of mechanical forces to the transducer directly subjects the semiconductor device to an electrical field generated by the piezoelectric material to thereby directly and rapidly change the number of carriers in the channel of the semiconductor device in proportion to the electrical field generated by the piezoelectric material and thus the stress-strain to which the transducer is subjected.

9. A stress-strain transducer according to claim 8 wherein the semiconductor device comprises a piezoresistive material so that the application of a force to the device affects the electrical resistance of the device, and wherein the piezoelectric material is selected and mounted to the device so that its effect on the number of carriers and the current magnitude in the device when the transducer is subjected to said forces and the effect of the potential applied to the source and drain electrodes is of like polarity as the change in current magnitude due to the piezoresistive effect of the device material.

10. A stress-strain transducer according to claim 8 including another gate electrode mounted to and electrically insulated from the semiconductor device and disposed on the side of the semiconductor device opposite from the first gate electrode, and wherein the semiconductor device has a thickness comparable to the Debye length of the material of which the semiconductor device is constructed.

11. A stress-strain transducer comprising a thin layer of a semiconductor material having conductive source and drain electrodes at the opposite ends of a semiconductor channel, a gate electrode mounted to and insulated from the semiconductor material and disposed over the channel, a piezoelectric material attached to and having a direct electrical flux coupling to the semiconductor material and disposed over the channel, and means providing a drain voltage to the source and drain and a constant gate voltage to the gate, so that application of mechanical forces to the transducer causes variations in the electric field of the piezoelectric material to thereby change the electric charge of the semiconductor channel and current flowing through the semiconductor material thereby becomes a function of the quantum of mechanical stress-strAin applied to the transducer.

12. A stress-strain transducer according to claim 11 wherein the gate electrode is mounted to the piezoelectric material and insulated from the semiconductor material by the piezoelectric material.