US3901067A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor gas detector and method therefor
Assignee: General Monitors Inc
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Filing: 1973-06-21
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Granted: 1975-08-26
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Expires: 1993-06-21
Abstract
Abstract Thin film semiconductor articles capable of detecting hydrogen sulfide in an atmosphere at relatively low temperatures. Semiconductor films comprising principally stannic oxide have been found to exhibit substantial decreases in resistance in relatively short times when contacted with as little as 1 ppm of hydrogen sulfide.
Inventors
- 👤 Jr William W Boardman
- 👤 Robert H Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:41
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
69 words
AN ARTICLE COMPRISING A THIN FILM SEMICONDUCTOR COATED ON AN INERT, REFACTORY SUBSTRATE, SAID FILM BEING PRINCIPALLY COMPRISED OF STANNIC OXIDE DOPED WITH A DOPANT SELECTED FROM THE GROUP CONSISTING OF ZINC, CADIUM, ALUMINUM, GALLIUM, INDIUM, TELLURIUM, ARSENCI, ANTIMONY, BISMUTH OR PALLADIUM, AND DIMINISHING IN RESISTIVITY WITH INCREASED ATMOSPHERIC CONCENTRATION OF HYDROGEN SULFIDE WHEN PLACED ABOUT 130*C IN AN AIR ATMOSPHERE CONTAINING AT LEAST ABOUT 1 PPM HYDROGEN SULFIDE.
Claim 2
Dependent Claim
69 words
AN ARTICLE COMPRISING A THIN FILM SEMICONDUCTOR COATED ON AN INERT, REFACTORY SUBSTRATE, SAID FILM BEING PRINCIPALLY COMPRISED OF STANNIC OXIDE DOPED WITH A DOPANT SELECTED FROM THE GROUP CONSISTING OF ZINC, CADIUM, ALUMINUM, GALLIUM, INDIUM, TELLURIUM, ARSENCI, ANTIMONY, BISMUTH OR PALLADIUM, AND DIMINISHING IN RESISTIVITY WITH INCREASED ATMOSPHERIC CONCENTRATION OF HYDROGEN SULFIDE WHEN PLACED ABOUT 130*C IN AN AIR ATMOSPHERE CONTAINING AT LEAST ABOUT 1 PPM HYDROGEN SULFIDE.
Claim 3
Dependent Claim
16 words
An article according to claim 1 wherein said film is an aluminum doped stannic oxide semiconductor.
Claim 4
Dependent Claim
22 words
An article according to claim 2 wherein said film arises from oxidation on said substrate of solution deposited tin and aluminum salts.
Claim 5
Dependent Claim
86 words
An article according to claim 2 wherein the resistivity of said film in hydrogen sulfide-free air at about 130*C is within the range (a) from about 108 to about 103 ohms per square and at that same temperature in an air atmosphere containing about 100 ppm hydrogen sulfide within the range (b) from about 104 to about 102 ohms per square, said resistivity decreasing at least about one order of magnitude with hydrogen sulfide concentration increasing from about 0 to about 100 ppm in said atmosphere.
Claim 6
Dependent Claim
43 words
An article according to claim 4 wherein said range (a) is from about 5 X 104 to about 2.0 X 107 ohms per square and wherein said range (b) is from about 4 X 103 to about 5 X 104 ohms per square.
Claim 7
Dependent Claim
55 words
An article according to claim 1, said substrate bearing on its surface electrical resistance heating means and, spaced apart therefrom, an electrode, said thin film semiconductor overlying said means and electrode and establishing electrical continuity therebetween, whereupon conductance of said semiconductor film can be determined by measuring current flow between said means and said electrode.
Claim 8
Dependent Claim
33 words
An article according to claim 6 wherein said substrate additionally bears temperature sensing means for controlling said resistance heating means to maintain said substrate at a constant temperature elevated with respect to ambient.
Claim 9
Independent Claim
90 words
A method of monitoring the hydrogen sulphide content of a gaseous atmosphere which comprises the steps of: a. exposing to said atmosphere a thin film semiconductor coated on an inert, refractory substrate said film being principally comprised of a stannic oxide and deminishing in resistivity with increasing atmospheric concentration of hydrogen sulphide when placed at about 130*C in an air atmosphere containing at least about 1 ppm hydrogen sulphide; b. monitoring the conductivity of said film; and c. generating a signal proportional to the conductivity of said film so monitored.
Claim 10
Independent Claim
90 words
A method of monitoring the hydrogen sulphide content of a gaseous atmosphere which comprises the steps of: a. exposing to said atmosphere a thin film semiconductor coated on an inert, refractory substrate said film being principally comprised of a stannic oxide and deminishing in resistivity with increasing atmospheric concentration of hydrogen sulphide when placed at about 130*C in an air atmosphere containing at least about 1 ppm hydrogen sulphide; b. monitoring the conductivity of said film; and c. generating a signal proportional to the conductivity of said film so monitored.
Claim 11
Dependent Claim
17 words
The method of claim 8 wherein the temperature of said film is elevated with respect to ambient.
Claim 12
Dependent Claim
18 words
The method of claim 9 wherein said temperature is within the range from about 100*C to about 150*C.
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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |