Patent US3700980A successfully refreshed from Google Patents.
US3700980A
Expired / Lapsed
US
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Schottky barrier phototransistor
Assignee: Texas Instruments Inc
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Filing: 1971-04-08
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Granted: 1972-10-24
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Expires: 1991-04-08
Abstract
Abstract Disclosed is a metal-semiconductor-metal phototransistor formed by a pair of closely spaced, thin metal films in rectifying contact with the surface of a lightly doped p-type indium arsenide substrate. The spacing between the metal films is substantially less than the diffusion length of a minority carrier in the indium arsenide at the operating temperature, which is on the order of -78* C. One metal film may be considered the collector region, the semiconductor material the base region, and the other metal film the emitter region. When the transistor is biased like an NPN transistor, the collector current is varied in proportion to the radiation striking the base region generally in the same manner as a photodiode, but the current modulation is many times that produced by a photodiode for a given radiation level.
Inventors
- 👤 Melvin Belasco
- 👤 Sebastian R Borrello
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:08
CPC Classifications
H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/24; H10F30/245; H10F99/00; Y; Y10; Y10S; Y10S257/00; Y10S257/902
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
23 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said rectifying junctions between said pair of metal films and said semiconductor body are schottky barriers.
Claim 2
Dependent Claim
38 words
The metal-semiconductor-metal phototransistor of claim 1 wherein the gain thereof is proportional to the ratio of the minority carrier diffusion length in said semiconductor body at the operating temperature to the spacing between said pair of metal films.
Claim 3
Dependent Claim
21 words
The metal-semiconductor-metal phototransistor of claim 1 and further including a metal layer on the opposite major surface of said semiconductor body.
Claim 4
Dependent Claim
30 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body is the base region thereof, and wherein said pair of metal films are respectively the emitter and collector regions thereof.
Claim 5
Dependent Claim
57 words
The metal-semiconductor-metal phototransistor of claim 1 wherein each of said pair of metal films have a plurality of spaced fingers formed along one edge thereof with the fingers on one of said metal films being interdigitated with the fingers on the other of said metal films, and wherein the spacing between adjacent fingers being said selected distance.
Claim 6
Dependent Claim
33 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body is an N-type substrate of indium arsenide having a P-type doped region formed in one surface thereof to provide said one major surface.
Claim 7
Dependent Claim
15 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body is a III-V compound semiconductor.
Claim 8
Dependent Claim
34 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body is taken from the group consisting of indium arsenide (InAs), indium antimonide (InSb), gallium antimonide (GaSb), gallium arsenide (GaAs), and indium-gallium arsenide (InxGa1 xAs).
Claim 9
Dependent Claim
28 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body has a p-type surface with a net acceptor surface concentration of less than about 1 X 1017 atoms/cc.
Claim 10
Dependent Claim
27 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body has a p-type surface with a net acceptor concentration of less than about 1 X 1018 atoms/cc.
Claim 11
Dependent Claim
28 words
The metal-semiconductor-metal phototransistor of claim 1 wherein said semiconductor body has a p-type surface with a net acceptor surface concentration of less than about 5 X 1016 atoms/cc.
References Cited (Backward Citations)
US3222530A
Cited
US3448349A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |