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US4186410A
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Nonalloyed ohmic contacts to n-type Group III(a)-V(a) semiconductors
Assignee: AT&T Inc
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Filing: 1978-06-27
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Granted: 1980-01-29
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Expires: 1998-06-27
Abstract
Abstract A nonalloyed ohmic contact (110-112, 120-122) to an n-type Group III(a)-V(a) compound semiconductor body (102-104) is formed by epitaxially growing a Group III(a)-V(a) n++-layer (106-108, 106'-108') doped to at least 1019 cm-3 between the semiconductor body and a metal contact layer (110-112). The metal layer forms an ohmic contact without requiring heating above the eutectic temperature. In order to avoid contamination of the metal-semiconductor interface, a metal contact layer (120-122) may be deposited in situ after MBE growth of the n++-layer. This technique results in both a metal-semiconductor interface with smoother morphology and also an ohmic contact without heating above the eutectic temperature. These procedures are specifically described with reference to the fabrication of GaAs FETs.
Inventors
- 👤 Alfred Y. Cho
- 👤 James V. Di Lorenzo
- 👤 William C. Niehaus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:54
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/80; H10D30/87; H10D64/00; H10D64/01; H10D64/011; H10D64/0116; H10D64/60; H10D64/62; H10P; H10P14/00; H10P14/20; H10P14/22; H10P14/29; H10P14/2901; H10P14/2907; H10P14/2911; H10P14/32; H10P14/3202; H10P14/3214; H10P14/3221; H10P14/34; H10P14/3402; H10P14/3414; H10P14/3421; H10D62/00; H10D62/80; H10D62/85; Y; Y10; Y10S; Y10S148/00; Y10S148/018; Y10S148/02; Y10S148/088
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
59 words
A device comprising an n-type body of a Group III(a)-V(a) compound semiconductor material, an n ++ -layer of a Group III(a)-V(a) compound semiconductor material epitaxially grown on said body and substantially lattice-matched thereto, said layer having a carrier concentration in excess of 10 19 cm -3 , and a nonalloyed, ohmic metal contact formed on said n ++ -layer.
Claim 2
Independent Claim
59 words
A device comprising an n-type body of a Group III(a)-V(a) compound semiconductor material, an n ++ -layer of a Group III(a)-V(a) compound semiconductor material epitaxially grown on said body and substantially lattice-matched thereto, said layer having a carrier concentration in excess of 10 19 cm -3 , and a nonalloyed, ohmic metal contact formed on said n ++ -layer.
Claim 3
Dependent Claim
13 words
The device of claim 1 wherein said body and said layer comprise GaAs.
Claim 4
Dependent Claim
12 words
The device of claim 2 wherein said layer is doped with Sn.
Claim 5
Independent Claim
27 words
The device of claims 1 or 2 wherein said contact comprises a metal selected from the group consisting of Au, Sn, Pt, Mo, Ta, Ti and AuGe.
Claim 6
Independent Claim
31 words
The device of claims 1, 2, 3 or 4 wherein said n ++ -layer is epitaxially grown by MBE and said contact is deposited in situ after said layer is grown.
Claim 7
Dependent Claim
88 words
A field effect transistor comprising a semi-insulating semiconductor body of a Group III(a)-V(a) compound material, an n-type epitaxial channel layer of said material epitaxially grown on said body, a pair of stripe mesa n ++ -type source and drain zones of said material epitaxially grown on said channel layer and doped to a carrier concentration in excess of 10 19 cm -3 , nonalloyed, ohmic, metal source and drain contacts formed on said zones, and a metal gate contact formed on said channel layer and between said zones.
Claim 8
Dependent Claim
88 words
A field effect transistor comprising a semi-insulating semiconductor body of a Group III(a)-V(a) compound material, an n-type epitaxial channel layer of said material epitaxially grown on said body, a pair of stripe mesa n ++ -type source and drain zones of said material epitaxially grown on said channel layer and doped to a carrier concentration in excess of 10 19 cm -3 , nonalloyed, ohmic, metal source and drain contacts formed on said zones, and a metal gate contact formed on said channel layer and between said zones.
Claim 9
Dependent Claim
35 words
The transistor of claim 6 wherein said material comprises GaAs, and said source and drain contacts comprise a layer of metal selected from the group consisting of Au, Sn, Pt, Mo, Ta, Ti and AuGe.
Claim 10
Dependent Claim
13 words
The transistor of claim 6 wherein said source and drain contacts comprise AuGe-Ag-Au.
Claim 11
Dependent Claim
61 words
The transistor of claims 6, 7, or 8 wherein said n ++ -type zones are epitaxially grown by MBE in the form of a unitary layer, said source and drain contacts are deposited in situ in the form of a unitary layer, and said source and drain n ++ -type zones and ohmic contacts are formed by shaping said unitary layers.
Claim 12
Independent Claim
73 words
A method of forming a nonalloyed, ohmic contact on an n-type body of a Group III(a)-V(a) compound semiconductor material comprising the steps of (a) epitaxially growing an n ++ -layer of said material on said body so as to have a carrier concentration in excess of 10 19 cm -3 , and (b) depositing a metal layer on said n ++ -layer without heating above the eutectic temperature, thereby forming said ohmic contact.
Claim 13
Independent Claim
73 words
A method of forming a nonalloyed, ohmic contact on an n-type body of a Group III(a)-V(a) compound semiconductor material comprising the steps of (a) epitaxially growing an n ++ -layer of said material on said body so as to have a carrier concentration in excess of 10 19 cm -3 , and (b) depositing a metal layer on said n ++ -layer without heating above the eutectic temperature, thereby forming said ohmic contact.
Claim 14
Dependent Claim
33 words
The method of claim 10 wherein step (a) includes growing said n ++ -layer by MBE, and step (b) includes depositing said metal layer in situ after said n ++ -layer is grown.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-01-28 | 1983-07-30 | 1984-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-01-28 | 1987-07-30 | 1988-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-01-28 | 1991-07-30 | 1992-01-29 | $7700.00 | Window Closed / Lapsed |