US5389554A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for fabricating microwave heterojunction bipolar transistors with emitters designed for high power applications
Assignee: Texas Instruments Inc
•
Filing: 1993-11-30
•
Granted: 1995-02-14
•
Expires: 2013-11-30
Abstract
Abstract In one form of the invention, an emitter structure for a bipolar transistor is disclosed. The structure is comprised of an emitter layer 6 of AlxGa1-xAs, where x>0.4, abutting a base layer 8.
Inventors
- 👤 William U. C. Liu
- 👤 Darrell G. Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:36
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/021; H10D62/00; H10D62/10; H10D62/13; H10D62/133; H10D62/136; H10D62/80; H10D62/85; H10D62/852; Y; Y10; Y10S; Y10S148/00; Y10S148/072; Y10S438/00; Y10S438/936
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
59 words
A method for fabrication of heterojunction bipolar transistors having a plurality of emitter fingers, comprising the step of: epitaxially depositing an emitter layer of Al x Ga 1-x As, where x>0.4, said emitter layer is adjacent a base layer, whereby said emitter layer provides a ballasting resistance to distribute a current approximately evenly through each of said emitter fingers.
Claim 2
Independent Claim
59 words
A method for fabrication of heterojunction bipolar transistors having a plurality of emitter fingers, comprising the step of: epitaxially depositing an emitter layer of Al x Ga 1-x As, where x>0.4, said emitter layer is adjacent a base layer, whereby said emitter layer provides a ballasting resistance to distribute a current approximately evenly through each of said emitter fingers.
Claim 3
Dependent Claim
23 words
The method of claim 1 further comprising the step of forming said emitter layer to have a graded junction with said base layer.
Claim 4
Dependent Claim
24 words
The method of claim 1 further comprising the step of doping said emitter layer to a concentration of approximately 5×10 17 atoms/cm 3 .
Claim 5
Dependent Claim
17 words
The method of claim 1 wherein the thickness of said emitter layer is less than 1 μm.
Claim 6
Independent Claim
59 words
A method for fabrication of a heterojunction bipolar transistor, comprising the steps: forming a ballast resistor layer of Al x Ga 1-x As, where x>0.4; and forming an emitter layer of Al x Ga 1-x As, where x<0.4, abutting a base layer, whereby a conventional base emitter junction is formed while retaining the advantages of an emitter ballast resistor.
Claim 7
Independent Claim
59 words
A method for fabrication of a heterojunction bipolar transistor, comprising the steps: forming a ballast resistor layer of Al x Ga 1-x As, where x>0.4; and forming an emitter layer of Al x Ga 1-x As, where x<0.4, abutting a base layer, whereby a conventional base emitter junction is formed while retaining the advantages of an emitter ballast resistor.
Claim 8
Dependent Claim
26 words
The method of claim 5 further comprising the step of grading the Al mole fraction of the junction between said emitter layer and said base layer.
Claim 9
Dependent Claim
15 words
The method of claim 6 wherein said grading occurs over a distance of 300 Angstroms.
Claim 10
Dependent Claim
24 words
The method of claim 5 further comprising the step of doping said emitter layer to a concentration of approximately 5×10 17 atoms/cm 3 .
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) | 1998-02-13 | 1998-08-15 | 1999-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-02-13 | 2002-08-15 | 2003-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-02-13 | 2006-08-15 | 2007-02-14 | $7700.00 | Window Closed / Lapsed |