Patent US4353027A successfully refreshed from Google Patents.
US4353027A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Contactless resistivity measurement method and apparatus
Assignee: United States Department of the Army
•
Filing: 1980-10-27
•
Granted: 1982-10-05
•
Expires: 2000-10-27
Abstract
Abstract Methods and apparatus for contactless, non-destructive resistivity measurnts on semiconducting crystalline material, for example gallium arsenide. The material to be tested is formed into a disc which is supported within an air gap. The holder for the disc is such as to support the disc only about its outer edges; thus, the disc is free to vibrate piezoelectrically. A measuring circuit connected to the electrodes, which establish the air gap, applies an alternating electric field in the air gap which causes the crystal to vibrate. By adjusting the frequency of excitation, resonance may be established in the crystal and by comparing the current drawn through the air gap with graphs previously established for material of the type under test, the resistivity of the disc can be determined.
Inventors
- 👤 Arthur Ballato
- 👤 Gerald J. Iafrate
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:15
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/282; G01R31/2831; G01R27/00; G01R27/02
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
109 words
A non-destructive, contactless method of measuring the resistivity of a semiconducting crystalline material, which comprises the steps of: (a) supporting a disc of said semiconducting crystalline material in an air gap in such a manner that the disc is free to vibrate; (b) establishing an alternating electric field in said air gap thereby to cause said disc to vibrate piezoelectrically; (c) adjusting the frequency of said alternating electric field to drive said disc into and beyond resonance; and (d) comparing the current drawn by said disc in step (c) above with previously prepared characteristic graphs for said crystalline material thereby to determine the resistivity of the sample under test.
Claim 2
Dependent Claim
109 words
A non-destructive, contactless method of measuring the resistivity of a semiconducting crystalline material, which comprises the steps of: (a) supporting a disc of said semiconducting crystalline material in an air gap in such a manner that the disc is free to vibrate; (b) establishing an alternating electric field in said air gap thereby to cause said disc to vibrate piezoelectrically; (c) adjusting the frequency of said alternating electric field to drive said disc into and beyond resonance; and (d) comparing the current drawn by said disc in step (c) above with previously prepared characteristic graphs for said crystalline material thereby to determine the resistivity of the sample under test.
Claim 3
Dependent Claim
42 words
The method according to claim 1 wherein said supporting step comprises: (e) positioning said disc on an insulating support member located between first and second excitation electrodes, said support member being dimensioned to support said disc only along the outer periphery thereof.
Claim 4
Dependent Claim
27 words
The method according to claim 1 including the further step of: (e) adjusting the size of said air gap to optimize the piezoelectric vibration of said disc.
Claim 5
Dependent Claim
23 words
The method according to claim 1 including the further step of: (e) shielding the air gap and semiconducting disc from extraneous electric fields.
Claim 6
Dependent Claim
25 words
The method according to claim 1 including the further step of: (e) establishing a vacuum around at least the air gap and the semiconducting disc.
Claim 7
Dependent Claim
32 words
The method according to claim 1 including the further step of: (e) establishing relative motion between the disc and the electrodes thereby to measure the resistivity of different regions of said disc.
Claim 8
Dependent Claim
86 words
Apparatus for the non-destructive, contactless measurement of the resistivity of a semiconducting crystalline material, which comprises: (a) first and second, spaced apart electrodes, said electrodes defining an air gap therebetween; (b) means for positioning a disc of said semiconductive material within said air gap; and (c) means, connected to said electrodes, for establishing an alternating electric field in said air gap, said alternating electric field causing said disc to vibrate piezoelectrically, said field establishing means including means for measuring the current flowing through said air gap.
Claim 9
Dependent Claim
86 words
Apparatus for the non-destructive, contactless measurement of the resistivity of a semiconducting crystalline material, which comprises: (a) first and second, spaced apart electrodes, said electrodes defining an air gap therebetween; (b) means for positioning a disc of said semiconductive material within said air gap; and (c) means, connected to said electrodes, for establishing an alternating electric field in said air gap, said alternating electric field causing said disc to vibrate piezoelectrically, said field establishing means including means for measuring the current flowing through said air gap.
Claim 10
Dependent Claim
34 words
The apparatus according to claim 7 wherein said disc positioning means comprising: (a) a non-conductive holder dimensioned to support said disc only about the outer periphery thereof, whereby said disc is free to vibrate.
Claim 11
Dependent Claim
26 words
The apparatus according to claim 7 further comprising: (d) means for altering the distance between said electrodes, thereby to alter the size of said air gap.
Claim 12
Dependent Claim
34 words
The apparatus according to claim 7 further comprising: (d) means for establishing relative motion between said electrodes and said disc, whereby the resistivity of said disc is measured at several locations in the disc.
Claim 13
Dependent Claim
31 words
The apparatus according to claim 7 wherein said field establishing means includes: (d) means for altering the frequency of said electric field, thereby to drive said disc into and through resonance.
Claim 14
Dependent Claim
23 words
The apparatus according to claim 7 further comprising: (d) means for electrically shielding said air gap and said disc from external electrical fields.
Claim 15
Dependent Claim
23 words
The apparatus according to claim 7 further comprising: (d) means for establishing a vacuum around at least the air gap and the disc.
Claim 16
Dependent Claim
148 words
The apparatus according to claim 7 wherein said positioning means further comprises: (d) a first conveyor belt, positioned normal to the electric field established by said electrodes, for transporting said disc toward said air gap; (e) second and third, spaced-apart conveyor belts, positioned parallel to the electric field established by said electrodes, for receiving said disc from the discharge end of said first conveyor belt and transporting the same, along insulating rails, through said air gap, said disc being gripped by said second and third conveyor belts only at two points on the periphery thereof such that said disc is free to vibrate in the air gap; and (f) a fourth conveyor belt, positioned normal to the electric field established by said electrodes, for receiving said disc from the discharge end of said second and third conveyor belts, and for transporting said disc away from said air gap.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-04 | 1986-04-05 | 1986-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-04 | 1990-04-05 | 1990-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-04 | 1994-04-05 | 1994-10-05 | $7700.00 | Window Closed / Lapsed |