US4494133A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Infrared sensitive photo diode
Assignee: UK Secretary of State for Defence
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Filing: 1982-06-07
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Granted: 1985-01-15
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Expires: 2002-06-07
Abstract
Abstract A photo diode formed by a substrate of Cd x Hg 1-x Te covered with a layer of CdTe forming a p-n junction. The substrate may be p-type in which case the layer is n-type or vice versa. An array of photo diodes may be formed by covering the substrate with semi-insulating CdTe and forming islets of In on the CdTe. Heating causes In to diffuse into the CdTe doping it n-type. This results in regions of n-type CdTe surrounded by semi-insulating CdTe each region forming, with the substrate, a photo diode. The heating also causes diffusion between the Cd x Hg 1-x Te and CdTe to give a graded heterostructure. Electrical connections are made to the substrate, and each n-type region. The n-type CdTe region may alternatively be formed by molecular beam epitaxial growth techniques using a beam of In dopant.
Inventors
- 👤 Anthony B. Dean
- 👤 Robin F. C. Farrow
- 👤 Piero Migliorato
- 👤 Anthony M. White
- 👤 Gerald M. Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:03
CPC Classifications
H; H10; H10F; H10F39/00; H10F39/10; H10F39/12; H10F39/18; H10F39/184; H10F39/011; H10F39/016
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
55 words
An infra red sensitive photo diode comprising: a substrate of Cd x Hg 1-x Te of a first conductivity type, a layer of CdTe of a second conductivity type on the substrate, the substrate and layer forming a p-n heterojunction, and a plurality of electrical terminals respectively connected to the substrate and to the layer.
Claim 2
Dependent Claim
55 words
An infra red sensitive photo diode comprising: a substrate of Cd x Hg 1-x Te of a first conductivity type, a layer of CdTe of a second conductivity type on the substrate, the substrate and layer forming a p-n heterojunction, and a plurality of electrical terminals respectively connected to the substrate and to the layer.
Claim 3
Dependent Claim
26 words
The photo diode of claim 1 wherein regions of the substrate not covered by the CdTe layer are covered by a passivating layer of semi-insulating CdTe.
Claim 4
Dependent Claim
40 words
The photo diode of claim 2 formed into an array of photo diodes on the same Cd x Hg 1-x Te substrate with regions of CdTe of said second conductivity type electrically isolated from one another by the semi-insulating CdTe.
Claim 5
Dependent Claim
16 words
The photo diode of claim 1 wherein there is a graded heterostructure between the two materials.
Claim 6
Dependent Claim
20 words
The photo diode of claim 1 wherein the Cd x Hg 1-x Te is p-type and the CdTe is n-type.
Claim 7
Dependent Claim
28 words
The photo diode of claim 5 wherein the n-type CdTe is formed by diffusion of a group IIIa or VII donor dopant into a semi-insulating layer of CdTe.
Claim 8
Dependent Claim
11 words
The photo diode of claim 6 wherein the dopant is In.
Claim 9
Dependent Claim
39 words
The photo diode of claim 5 wherein x is in the range 0.2 to 0.3 inclusive and the acceptor concentration in the Cd x Hg 1-x Te material is in the range 1 to 5×10 16 cm - .
Claim 10
Dependent Claim
25 words
The photo diode of claim 5 wherein n-type region of the CdTe are doped to give the number of electrons, n>5×10 16 cm -3 .
Claim 11
Dependent Claim
20 words
The photo diode of claim 1 wherein the Cd x Hg 1-x Te is n-type and the CdTe is p-type.
Claim 12
Dependent Claim
22 words
The photo diode of claim 2 wherein the CdTe is a layer having a thickness in the range 0.2 to 1 μm.
Claim 13
Dependent Claim
77 words
The photo diode of claim 1 formed into an array comprising a substrate of p-type Cd x Hg 1-x Te having a surface passivated with a layer of semi-insulating CdTe, regions of n-type CdTe formed by In selectively deposited on the CdTe and diffused into the CdTe by heating in the range 70° to 120° C. each region of n-type CdTe providing a photo diode, and electrical contacts associated with each n-type region and with the substrate.
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) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |