US5087876A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for making surface photovoltage measurements of a semiconductor
Assignee: Semitest Inc
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Filing: 1990-07-16
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Granted: 1992-02-11
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Expires: 2010-07-16
Abstract
Abstract An apparatus for making ac surface photovoltage (SPV) measurements of a specimen of semiconductor material under variable dc bias voltage conditions includes a light source whose output beam is intensity modulated, a reference electrode, a guard electrode, a back electrode, a first voltage for biasing the reference electrode with a variable dc voltage and a second voltage separate from the first voltage for biasing the guard electrode such that an accumulation layer is established in the area on the specimen controlled by the guard electrode to prevent flow of carriers between the area controlled by the reference electrode and the rest of the specimen.
Inventors
- 👤 Leszek Reiss
- 👤 Emil Kamieniecki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:00
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/308
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
169 words
Apparatus for use in making ac surface photovoltage measurements of a specimen of semiconductor material under variable dc bias voltage conditions, said specimen having first and second major surfaces, said apparatus comprising: a. means for illuminating at least a portion of said first major surface of said specimen with a beam of intensity modulated light, b. a back electrode adapted to receive said second major surface of said specimen, c. a probe assembly positionable in the path of said light beam in close proximity to said first major surface of said specimen, said probe assembly comprising: i. a reference electrode, and ii. a guard electrode, d. first dc voltage means for applying a variable dc bias voltage between said back electrode and said reference electrode, and e. second voltage means independent of said first voltage means for applying a bias voltage between said back electrode and said guard electrodes. f. the ac surface photovoltage signals generated by said light beam appearing between said reference electrode and said back electrode.
Claim 2
Dependent Claim
169 words
Apparatus for use in making ac surface photovoltage measurements of a specimen of semiconductor material under variable dc bias voltage conditions, said specimen having first and second major surfaces, said apparatus comprising: a. means for illuminating at least a portion of said first major surface of said specimen with a beam of intensity modulated light, b. a back electrode adapted to receive said second major surface of said specimen, c. a probe assembly positionable in the path of said light beam in close proximity to said first major surface of said specimen, said probe assembly comprising: i. a reference electrode, and ii. a guard electrode, d. first dc voltage means for applying a variable dc bias voltage between said back electrode and said reference electrode, and e. second voltage means independent of said first voltage means for applying a bias voltage between said back electrode and said guard electrodes. f. the ac surface photovoltage signals generated by said light beam appearing between said reference electrode and said back electrode.
Claim 3
Dependent Claim
62 words
The apparatus of claim 1 wherein said specimen comprises two areas and wherein one area of the specimen is controlled by said reference electrode and another area of said specimen is controlled by said guard electrode and wherein the area of the specimen controlled by the reference electrode is completely surrounded by the area of the specimen controlled by the guard electrode.
Claim 4
Dependent Claim
35 words
The apparatus of claim 2 and wherein the second voltage means is such so as to produce an accumulation layer at the surface of the specimen which surrounds the area controlled by the reference electrode.
Claim 5
Dependent Claim
16 words
The apparatus of claim 3 and wherein the second voltage means is a fixed dc voltage.
Claim 6
Dependent Claim
16 words
The apparatus of claim 3 and wherein the second voltage means is a variable dc voltage.
Claim 7
Dependent Claim
25 words
The apparatus of claim 1 and wherein the back electrode is below the specimen and the reference electrode and guard electrode are above the specimen.
Claim 8
Dependent Claim
20 words
The apparatus of claim 1 and wherein the reference electrode is circularly shaped and the guard electrode is annularly shaped.
Claim 9
Dependent Claim
18 words
The apparatus of claim 7 and wherein the reference electrode and the guard electrode are both aluminum coatings.
Claim 10
Dependent Claim
37 words
The apparatus of claim 1 and wherein the guard electrode is above the specimen and wherein the area on the specimen controlled by the guard electrode is the area on the specimen directly below the guard electrode.
Claim 11
Dependent Claim
26 words
The apparatus of claim 1 and wherein the reference electrode is made of a material that is transparent to the light produced by the illuminating means.
Claim 12
Dependent Claim
20 words
The apparatus of claim 1 and wherein the bias voltage produced by the second voltage means is a dc voltage.
Claim 13
Dependent Claim
22 words
The apparatus of claim 11 and wherein the dc voltage produced by the second dc voltage means is a fixed dc voltage.
Claim 14
Dependent Claim
22 words
The apparatus of claim 11 and wherein the dc voltage produced by the second dc voltage means is a variable dc voltage.
Claim 15
Independent Claim
114 words
A method for making ac surface photovoltage measurements of a specimen of semiconductor material under variable dc bias voltage conditions, said specimen having first and second major surfaces, said method comprising: a. applying a variable dc voltage to a reference electrode positioned spaced from specimen, said reference electrode controlling an area on said specimen, b. illuminating at least a portion of said area on said specimen which is controlled by said reference electrode with a beam of intensity modulated light, c. establishing an accumulation layer on the specimen around the area which is controlled by the reference electrode, and d. measuring the surface photovoltage signal appearing between said reference electrode and a back electrode.
Claim 16
Independent Claim
114 words
A method for making ac surface photovoltage measurements of a specimen of semiconductor material under variable dc bias voltage conditions, said specimen having first and second major surfaces, said method comprising: a. applying a variable dc voltage to a reference electrode positioned spaced from specimen, said reference electrode controlling an area on said specimen, b. illuminating at least a portion of said area on said specimen which is controlled by said reference electrode with a beam of intensity modulated light, c. establishing an accumulation layer on the specimen around the area which is controlled by the reference electrode, and d. measuring the surface photovoltage signal appearing between said reference electrode and a back electrode.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-02-10 | 1995-08-12 | 1996-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-10 | 1999-08-12 | 2000-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-10 | 2003-08-12 | 2004-02-11 | $7700.00 | Window Closed / Lapsed |