US5323020A
Expired / Lapsed
US
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High performance MESFET with multiple quantum wells
Assignee: International Business Machines Corp
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Filing: 1992-12-22
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Granted: 1994-06-21
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Expires: 2012-12-22
Abstract
Abstract A superheterojunction Field Effect Transistor (FET) with a multi-region channel on a Silicon (Si) substrate. The FET is a Metal Semiconductor FET (MESFET) or, alternatively, a Junction FET (JFET). The multi-region channel has: A first region of Si extending from the FET's source to a point under the FET's gate, beyond the gate's midpoint; a second region extending from the first region to the FET's drain, comprised of a superlattice of alternating Si and SiGe layers; and, a third region of Si extending under the first two regions from the source to the drain. The first region has a laterally graded dopant that creates an accelerating electric field. The superlattice structure increases electron mobility and transit velocity.
Inventors
- 👤 S. Noor Mohammad
- 👤 Robert B. Renbeck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:06
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/80; H10D30/83; H10D30/832; H10D30/40; H10D30/47; H10D30/471; H10D30/473; H10D30/87; H10D30/875; H10D62/00; H10D62/10; H10D62/17; H10D62/213; H10D62/221; Y; Y10; Y10S; Y10S148/00; Y10S148/072; Y10S148/16
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
97 words
A Field Effect Transistor (RET) with a gate, a drain, a source and further comprising: a semi-insulating substrate; and a multi-region channel comprising: a first region of a first semiconductor material, said first region extending towards said drain from said source to a point under said gate beyond the midpoint of said gate, a second region comprised of a superlattice of quantum wells, said second region extending from said first region to said drain, and, a semi-insulating region on said semi-insulating substrate extending from said source to said drain under said first region and said second region.
Claim 2
Dependent Claim
97 words
A Field Effect Transistor (RET) with a gate, a drain, a source and further comprising: a semi-insulating substrate; and a multi-region channel comprising: a first region of a first semiconductor material, said first region extending towards said drain from said source to a point under said gate beyond the midpoint of said gate, a second region comprised of a superlattice of quantum wells, said second region extending from said first region to said drain, and, a semi-insulating region on said semi-insulating substrate extending from said source to said drain under said first region and said second region.
Claim 3
Dependent Claim
21 words
The FET of claim 1 wherein the superlattice comprises alternating layers of said first semiconductor material and a second semiconductor material.
Claim 4
Dependent Claim
14 words
The FET of claim 1 wherein said first semiconductor material is N + silicon.
Claim 5
Dependent Claim
19 words
The FET of claim 2 wherein said first semiconductor material is silicon and said second semiconductor material is SiGe.
Claim 6
Dependent Claim
25 words
The FET of claim 4 wherein said silicon layers are between 300 Å and 1000 Å thick and said SiGe layers are 200 Å thick.
Claim 7
Dependent Claim
28 words
The FET of claim 4 wherein the silicon layers are N + doped to a dopant density between 10 16 cm -3 and 5*10 16 cm -3 .
Claim 8
Dependent Claim
13 words
The FET of claim 4 wherein the mole fraction of Germanium in SiGe≦0.5.
Claim 9
Dependent Claim
11 words
The FET of claim 7 wherein the mole fraction of Germanium=0.5.
Claim 10
Dependent Claim
15 words
The FET of claim 1 wherein said multi-region channel has a laterally varying dopant density.
Claim 11
Dependent Claim
15 words
The FET of claim 1 wherein said first region has a laterally varying dopant density.
Claim 12
Dependent Claim
32 words
The FET of claim 10 wherein said laterally varying dopant density is a plurality of discrete dopant densities, whereby each of said dopant densities are in a portion of said first region.
Claim 13
Dependent Claim
47 words
The FET of claim 11 wherein said plurality of discrete dopant densities are distributed such that a maximum density is at said source, a minimum density is at the opposite end of said first region and the dopant densities uniformly decrease from said maximum to said minimum.
Claim 14
Dependent Claim
16 words
The FET of claim 1 wherein said gate is metal and said FET is a MESFET.
Claim 15
Dependent Claim
17 words
The FET of claim 1 wherein said gate is doped semiconductor and said FET is a JFET.
Claim 16
Dependent Claim
15 words
The FET of claim 1 wherein said semi-insulating region is a region of i-type silicon.
Claim 17
Dependent Claim
15 words
The FET of claim 1 wherein said semi-insulating region is an insulating region of sapphire.
Claim 18
Dependent Claim
17 words
The FET of claim 1 wherein said semi-insulating region is an insulating region of SiO 2 .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-06-20 | 1997-12-20 | 1998-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-20 | 2001-12-20 | 2002-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-20 | 2005-12-20 | 2006-06-21 | $7700.00 | Window Closed / Lapsed |