Patent US4845541A successfully refreshed from Google Patents.
US4845541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tunneling emitter bipolar transistor
Assignee: University of Minnesota System
•
Filing: 1988-06-06
•
Granted: 1989-07-04
•
Expires: 2008-06-06
Abstract
Abstract A bipolar transistor has a barrier layer interposed between its base and its emitter. The barrier layer is formed of a different, wider band gap, semiconductor material than the base and the emitter and has the same conductivity type as the emitter. The barrier layer exhibits a large difference in the effective electron mass and the effective whole mass, and presents a small barrier to majority carriers. The tunneling emitter bipolar transistor exhibits a comparable current gain while having better temperature stability, less light sensitivity, and a much lower emitter resistance (leading to a much higher cut-off frequency) than conventional heterojunction bipolar transistors.
Inventors
- 👤 Jingming Xu
- 👤 Michael Shur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:47
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/80; H10D62/82; H10D62/824; H10D62/10; H10D62/13; H10D62/165
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
118 words
A bipolar transistor comprising: a collector having a first conductivity type; a base having a highly doped second conductivity type; an emitter having the first conductivity type; and a barrier layer interposed between the base and the emitter, the barrier layer being heavily doped, first conductivity type, having a wider band gap than the emitter, and exhibiting a difference in effective electron mass and effective hole mass, the barrier layer having a thickness such that the barrer layer is substantially transparent to first conductivity type carriers and having a compositional gradient where the band gap varies as a function of distance from a junction between the base and the barrier layer to enhance tunneling in the barrier layer.
Claim 2
Dependent Claim
118 words
A bipolar transistor comprising: a collector having a first conductivity type; a base having a highly doped second conductivity type; an emitter having the first conductivity type; and a barrier layer interposed between the base and the emitter, the barrier layer being heavily doped, first conductivity type, having a wider band gap than the emitter, and exhibiting a difference in effective electron mass and effective hole mass, the barrier layer having a thickness such that the barrer layer is substantially transparent to first conductivity type carriers and having a compositional gradient where the band gap varies as a function of distance from a junction between the base and the barrier layer to enhance tunneling in the barrier layer.
Claim 3
Dependent Claim
27 words
The bipolar transistor of claim 1 wherein the barrier layer is formed by an alloy semiconductor which has a band gap which is a function of composition.
Claim 4
Dependent Claim
21 words
The bipolar transistor of claim 1 wherein the band gap of the barrier layer increases with the distance from the junction.
Claim 5
Dependent Claim
22 words
The bipolar transistor of claim 3 wherein band gaps of the barrier layer and the base are essentially equal at the junction.
Claim 6
Dependent Claim
15 words
The bipolar transistor of claim 1 wherein the emitter is heavily doped, first conductivity type.
Claim 7
Dependent Claim
31 words
The bipolar transistor of claim 1 wherein the collector and the emitter are formed by a first semiconductor material and the barrier layer is formed by a second alloy semiconductor material.
Claim 8
Dependent Claim
16 words
The bipolar transistor of claim 6 wherein the base is formed by the first semiconductor material.
Claim 9
Dependent Claim
16 words
The bipolar transistor of claim 6 wherein the base is formed by a third semiconductor material.
Claim 10
Dependent Claim
26 words
The bipolar transistor of claim 8 wherein the first semiconductor material is GaAs, the second semicondutor material is AlGaAs, and the third semiconductor material is GaBeAs.
Claim 11
Dependent Claim
13 words
The bipolar transistor of claim 6 wherein the first semiconductor material is GaAs.
Claim 12
Dependent Claim
13 words
The bipolar transistor of claim 10 wherein the second semiconductor material is AlGaAs.
Claim 13
Dependent Claim
13 words
The bipolar transistor of claim 10 wherein the second semiconductor material is InGaP.
Claim 14
Dependent Claim
13 words
The bipolar transistor of claim 6 wherein the first semiconductor material is InGaAs.
Claim 15
Dependent Claim
13 words
The bipolar transistor of claim 13 wherein the second semiconductor material is AlGaAs.
Claim 16
Dependent Claim
13 words
The bipolar transistor of claim 13 wherein the second semiconductor material is InAlAs.
Claim 17
Dependent Claim
22 words
The bipolar transistor of claim 1 wherein the barrier layer has a thickness of between about 10 Angstroms and about 200 Angstroms.
Claim 18
Dependent Claim
22 words
The bipolar transistor of claim 1 wherein the barrier layer has a thickness of between about 30 Angstroms and about 60 Angstroms.
Claim 19
Dependent Claim
22 words
The bipolar transistor of claim 1 wherein the first conductivity type is n type and the second conductivity type is p type.
Claim 20
Dependent Claim
23 words
The bipolar transistor of claim 1 wherein the barrier layer exhibits a large barrier to minority carrier injection than to majority carrier injection.
References Cited (Backward Citations)
US4163237A
Cited
US4286275A
Cited
US4380774A
Cited
US4672404A
Cited
US4672413A
Cited
US4679305A
Cited
US4691215A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-03 | 1993-01-02 | 1993-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-03 | 1997-01-02 | 1997-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-03 | 2001-01-02 | 2001-07-04 | $7700.00 | Window Closed / Lapsed |