EP0023723A2
Expired / Lapsed
EP
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Multistage avalanche photodetector
Assignee: AT&T Inc
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Filing: 1980-08-06
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Granted: —
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Expires: 2000-08-06
Abstract
Abstract A low noise multistage photodetector device (1) is formed from a sequence of pairs of layers of opposite conductivity type (10, 11; 12, 13; 13, 15) having heterojunctions between each pair. The second layer (11, 13, 15) of each pair has a bandgap which is larger than the bandgap of the first layer (10, 12, 14) of said pair. Electrodes (21, 22, 23) are formed on the device so that voltages (30, 31, 32) may be applied to reverse bias the heterojunctions formed between each pair in the sequence and to forward bias the heterojunctions formed between the second layer (11, 13, 15) of one pair and the first layer (12, 14) of another pair. The device provides traps for one sign of carrier, which traps prevent the trapped carrier from avalanching through amplification regions of the device.
Inventors
- 👤 John Mathew Worlock
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 01:39
CPC Classifications
H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/222; H10F30/225; H10F30/2255; H10F30/26
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
170 words
An avalanche photodetector comprising a plurality of abutting layers (10, 11, 12, 13, 14, 15) of semiconductor material of alternating opposed conductivity type, the layers being grouped into a sequence of pairs of layers (10, 11; 12, 13; 14, 15) from a first end to a second end of the photodetector, CHARACTERIZED IN THAT the bandgap of the material comprising the second layer (11; 13; 15) of each pair is larger than the bandgap of the material comprising the first layer (10; 12; 14) of said pair; and electrode means (21; 22; 23) are formed on the first layer of each pair of the sequence and on the second layer of the last pair of said sequence for reverse biasing the heterojunctions (1.1; 1.2; 1.3) formed at the interface between the first layer (10; 12; 14) and the second layer (11; 13; 15) of each pair of the sequence and for forward biasing the heterojunctions (1.4; 1.5) formed at the interface between the layers from different pairs of the sequence.
Claim 2
Dependent Claim
170 words
An avalanche photodetector comprising a plurality of abutting layers (10, 11, 12, 13, 14, 15) of semiconductor material of alternating opposed conductivity type, the layers being grouped into a sequence of pairs of layers (10, 11; 12, 13; 14, 15) from a first end to a second end of the photodetector, CHARACTERIZED IN THAT the bandgap of the material comprising the second layer (11; 13; 15) of each pair is larger than the bandgap of the material comprising the first layer (10; 12; 14) of said pair; and electrode means (21; 22; 23) are formed on the first layer of each pair of the sequence and on the second layer of the last pair of said sequence for reverse biasing the heterojunctions (1.1; 1.2; 1.3) formed at the interface between the first layer (10; 12; 14) and the second layer (11; 13; 15) of each pair of the sequence and for forward biasing the heterojunctions (1.4; 1.5) formed at the interface between the layers from different pairs of the sequence.
Claim 3
Dependent Claim
49 words
An avalanche photodetector according to claim 1, CHARACTERIZED IN THAT the bandgap of the material comprising the second layer (11; 13; 15) of each pair is larger than the bandgap of the material comprising the first layer (12; 14) of the pair of layers adjacent to said second layer.
Claim 4
Dependent Claim
60 words
An avalanche photodetector according to claim 1 or 2, CHARACTERIZED IN THAT the bandgap of the first layer (12) of at least one pair of the sequence is at least as large as the bandgap of the first layer (10) of another pair (10, 11) of said sequence, which another pair is closer to the first end of the photodetector.
Claim 5
Dependent Claim
28 words
An avalanche photodetector according to claim 3 CHARACTERIZED IN THAT the second layer of at least one pair of the sequence of pairs of layers is lightly doped.
Claim 6
Dependent Claim
61 words
An avalanche photodetector according to claim 3, CHARACTERIZED IN THAT the materials for the first layer and the second layer from at least one pair of the sequence are selected from the group consisting of quaternary compounds of InGaAsP, ternary compounds of InGaAs, ternary compounds of GaAsSb, ternary compounds of InSbAs, ternary compounds of InGaSb, binary compounds of CdTe, and Ge.
Claim 7
Dependent Claim
78 words
An avalanche photodetector according to claim 3, CHARACTERIZED IN THAT the materials for the first layer and the second layer from at least one pair of the sequence are chosen from the group of pairs of layers consisting of Al l-u Ga u As/In l-x Ga x As y P l-y , Al l-u Ga u As v Sb l-v /In l-x Ga x As y P l-y and InP/Al l-z (In l-y Ga y As) z .
Claim 8
Dependent Claim
129 words
An avalanche photodetector according to claims 1, 2 or 3 further comprising a window substrate layer (410), for accepting incident radiation (200), disposed adjacent to the first pair (210, 220) of the pairs of layers, wherein the electrode means (120, 21) are formed on the window substrate layer, on the first layer (230) of each pair of the sequence other than the first layer (210) of the first pair (210, 220), and on the second layer (240) of the last pair of the sequence for reverse biasing the heterojunctions (300; 302) formed at the interface between the first layer and the second layer of each pair of the sequence and for forward biasing the heterojunctions (301) formed at the interface between the layers from different pairs of the sequence.
Claim 9
Dependent Claim
21 words
An avalanche photodetector according to claim 7, CHARACTERIZED IN THAT the window substrate layer (410) is an antireflection dielectric interference coating.
Claim 10
Dependent Claim
36 words
An avalanche photodetector according to claim 7, CHARACTERIZED IN THAT the window substrate layer is a semiconductor material having a bandgap larger than the bandgap of the first layer of the first pair of the sequence.
References Cited (Backward Citations)
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