Patent US4075651A successfully refreshed from Google Patents.
US4075651A
Expired / Lapsed
US
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High speed fet employing ternary and quarternary iii-v active layers
Assignee: Varian Medical Systems Inc
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Filing: 1976-03-29
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Granted: 1978-02-21
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Expires: 1996-03-29
Abstract
Abstract A field effect transistor (FET) preferably employs an epitaxial layer of indium gallium arsenide as its active layer. On the surface of the active layer, ohmic source and drain contacts are spaced from respectively opposite sides of a Schottky barrier (rectifying) gate electrode. The active layer is grown over an epitaxial transition layer which is graded from gallium arsenide to indium gallium arsenide and is doped with chromium or oxygen to be semi-insulating. The transition layer is in turn formed over a bulk, intrinsic layer of gallium arsenide. High speed operation of the FET is obtainable because the active layer has excellent electron transport characteristics. Other materials suitable for the active layer are indium arsenide phosphide and indium gallium arsenide phosphide.
Inventors
- 👤 Lawrence W. James
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:33
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/60; H10D64/64; H10D30/00; H10D30/80; H10D30/87; H10D62/00; H10D62/10; H10D62/124; H10D62/126; H10D62/80; H10D62/85; H10D62/852; Y; Y10; Y10S; Y10S148/00; Y10S148/056; Y10S148/072; Y10S148/088; Y10S148/119; Y10S148/139
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
98 words
A high-speed field effect transistor comprising an active epitaxial layer of a predetermined conductivity type, a rectifying gate contact and ohmic source and drain contacts on said active layer, said gate contact being positioned to control current flow between said source and drain contacts, said active layer comprising a compound of at least three elements selected from columns III and V of the Periodic Table and doped to be of a predetermined conductivity type, said compound being In 1-x Ga x As 1-y P y , where x + y is greater than 0.5 and less than 1.
Claim 2
Dependent Claim
98 words
A high-speed field effect transistor comprising an active epitaxial layer of a predetermined conductivity type, a rectifying gate contact and ohmic source and drain contacts on said active layer, said gate contact being positioned to control current flow between said source and drain contacts, said active layer comprising a compound of at least three elements selected from columns III and V of the Periodic Table and doped to be of a predetermined conductivity type, said compound being In 1-x Ga x As 1-y P y , where x + y is greater than 0.5 and less than 1.
Claim 3
Dependent Claim
23 words
The transistor of claim 1 wherein said compound is indium gallium arsenide, wherein the mol fraction of gallium arsenide is greater than 0.5.
Claim 4
Dependent Claim
40 words
The transistor of claim 2 wherein said active layer is formed over an epitaxial layer which is graded from gallium arsenide to indium gallium arsenide, said epitaxial layer being in turn formed upon a bulk material substrate of gallium arsenide.
Claim 5
Dependent Claim
12 words
The transistor of claim 1 wherein said compound is indium arsenide phosphide.
Claim 6
Dependent Claim
40 words
The transistor of claim 4 wherein said active layer is formed over an epitaxial layer which is graded from indium phosphide to indium arsenide phosphide, said epitaxial layer being in turn formed upon a bulk material substrate of indium phosphide.
Claim 7
Dependent Claim
16 words
The transistor of claim 1 wherein said active layer is formed over a bulk material substrate.
Claim 8
Dependent Claim
41 words
The transistor of claim 1 wherein said active layer is formed over an epitaxial layer which is graded from indium phosphide to indium gallium arsenide phosphide, said epitaxial layer being in turn formed upon a bulk material substrate of indium phosphide.
Claim 9
Dependent Claim
22 words
The transistor of claim 1 wherein said source, gate, and drain contacts are formed upon a common surface of said active layer.
Claim 10
Dependent Claim
37 words
The transistor of claim 1 further including a supporting layer of semiconductive material under said active layer, said supporting layer having a very high resistivity so as not to form a significant shunt across said active layer.
Claim 11
Dependent Claim
29 words
The transistor of claim 9 wherein said supporting layer is an epitaxial layer and further including a substrate under said supporting layer, said substrate being formed of bulk material.
Claim 12
Dependent Claim
65 words
The transistor of claim 10 wherein said substrate is gallium arsenide, said supporting layer is gradually graded from gallium arsenide at the bottom portion thereof to indium gallium arsenide at the top portion thereof and is doped with a material selected from the class consisting of chromium and oxygen, and wherein said active layer is indium gallium arsenide and is doped with an n-type dopant.
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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) | 1981-02-20 | 1981-08-22 | 1982-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-20 | 1985-08-22 | 1986-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-20 | 1989-08-22 | 1990-02-21 | $7700.00 | Window Closed / Lapsed |