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US3645631A
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US
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Apparatus and method for measuring the carrier concentration of semiconductor materials
Assignee: GTE Sylvania Inc
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Filing: 1970-05-05
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Granted: 1972-02-29
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Expires: 1990-05-05
Abstract
Abstract Technique of measuring the free carrier concentration in a silicon specimen by passing a beam of infrared or far infrared energy from a laser through a body of intrinsic germanium to impinge on a surface of the silicon specimen which contacts the germanium at an optically flat interface. The angle of incidence is varied until substantially all of the incident radiation is reflected and detected by a photodetector. This angle of incidence is designated the critical angle and is a measure of the carrier concentration of the silicon specimen.
Inventors
- 👤 Dinesh C Gupta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:39
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/41; G01N21/43
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
51 words
Apparatus for measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 1 wherein the surface of the body and the surface of the specimen of semiconductor material which contact at the common interface are both optically flat; and the source of radiant energy is a laser.
Claim 2
Dependent Claim
72 words
Apparatus for measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 2 including means for rotating the body and the specimen of semiconductor material about an axis parallel to the plane of the interface of the body and the specimen of semiconductor material; and means for directing the beam of radiant energy in a plane perpendicular to the plane of the interface and perpendicular to the axis.
Claim 3
Dependent Claim
42 words
Apparatus for measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 3 wherein the laser includes means for polarizing the beam of radiant energy from the laser in a plane parallel to the plane of the interface.
Claim 4
Dependent Claim
30 words
Apparatus for measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 4 wherein the specimen is of silicon; and the body is of intrinsic germanium.
Claim 5
Dependent Claim
49 words
Apparatus for measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 5 wherein the body of germanium is one-half of a right circular cylinder having an optically flat planar surface opposite the curved surface for contacting the surface of the specimen of semiconductor material.
Claim 6
Dependent Claim
26 words
Apparatus for measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 5 wherein the body of germanium is a Dove prism.
Claim 7
Independent Claim
153 words
The method of measuring the carrier concentration of a specimen of semiconductor material comprising the steps of placing a surface of a body of a material which is optically more dense than the specimen of semiconductor material to be measured in contact with a surface of a specimen of semiconductor material; directing a beam of radiant energy onto said body so that the radiant energy passes through the body and impinges on the interface between the body and the specimen of semiconductor material; varying the angle of incidence at which the beam of radiant energy passing through the body impinges on the interface, and simultaneously detecting the amount of radiant energy reflected from the interface; and measuring the angle of incidence when the amount of radiant energy detected indicates that substantially all the incident radiant energy is being reflected, thereby providing a measure of the carrier concentration of the specimen of semiconductor material.
Claim 8
Dependent Claim
137 words
The method of measuring the carrier concentration of a specimen of semiconductor material in accordance with claim 8 including placing an optically flat surface of the body of a material which is optically more dense than the specimen of semiconductor material to be measured in contact with an optically flat surface of the specimen of semiconductor material; directing a beam of coherent monochromatic radiant energy from a laser onto said body, said beam lying in a plane perpendicular to the interface between the optically flat surface of the body and the specimen of semiconductor material; and varying the angle of incidence at which the beam of radiant energy impinges on the interface by rotating the body and the specimen of semiconductor material about an axis parallel to the interface and perpendicular to the plane of the beam.
Claim 9
Independent Claim
193 words
The method of measuring the carrier concentration of a specimen of silicon comprising placing the optically flat planar surface of a half-right circular cylindrically shaped body of intrinsic germanium in contact with an optically flat surface of a specimen of silicon; directing a beam of plane-polarized coherent monochromatic radiant energy from a laser onto the curVed surface of the body of germanium so that the radiant energy passes through the body and impinges on the interface between the body and the specimen, said beam lying in a plane perpendicular to the interface, and the plane of polarization of the radiant energy being parallel to the interface; varying the angle of incidence at which the beam of radiant energy impinges on the interface by rotating the body and the specimen about an axis parallel to the interface and perpendicular to the plane of the beam, and simultaneously detecting the amount of radiant energy reflected from the interface; and measuring the angle of incidence when the amount of radiant energy detected indicates that substantially all the incident radiant energy is being reflected, thereby providing a measure of the carrier concentration of the specimen of silicon.
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) | 1975-02-28 | 1975-08-30 | 1976-02-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-28 | 1979-08-30 | 1980-02-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-28 | 1983-08-30 | 1984-02-29 | $7700.00 | Window Closed / Lapsed |