US4821082A
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Heterojunction bipolar transistor with substantially aligned energy levels
Assignee: International Business Machines Corp
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Filing: 1987-10-30
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Granted: 1989-04-11
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Expires: 2007-10-30
Abstract
Abstract Heterojunction bipolar transistors are disclosed having an energy band offset in the valence or conduction band and the other of the bands being substantially aligned at the heterojunction. For an npn transistor the conduction band is substantially aligned and the bandgap difference is in the valence band. A pnp type transistor is also disclosed wherein all the bandgap difference is in the conduction band and the valence band is substantially aligned. The npn type transistor provides improved hole confinement in the base as well as enhanced electron injection and collection. In one embodiment of a double heterojunction bipolar transistor, materials are selected that utilize Ga compounds in the base and Al and/or In compounds in the emitter and collector, which have a valence band offset of approximately 400 meV or greater and an aligned conduction band at both of the heterojunctions.
Inventors
- 👤 David J. Frank
- 👤 Ronald F. Marks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:47
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/80; H10D10/821
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
122 words
A heterojunction bipolar transistor comprising: a collector layer of a first conductivity type; a base layer of a second conductivity type forming a first junction with said collector layer; and an emitter layer of the first conductivity type forming a second junction with said base layer; at least one of the first and second junctions being between different semiconductor materials thereby forming at least one heterojunction, the semiconductor materials of each of said collector, base and emitter layers having conduction and valence band energy levels wherein the energy levels of one of said bands are substantially aligned at said at least one heterojunction and an abrupt energy level offset occurs in the other of said bands at said at least one heterojunction.
Claim 2
Dependent Claim
122 words
A heterojunction bipolar transistor comprising: a collector layer of a first conductivity type; a base layer of a second conductivity type forming a first junction with said collector layer; and an emitter layer of the first conductivity type forming a second junction with said base layer; at least one of the first and second junctions being between different semiconductor materials thereby forming at least one heterojunction, the semiconductor materials of each of said collector, base and emitter layers having conduction and valence band energy levels wherein the energy levels of one of said bands are substantially aligned at said at least one heterojunction and an abrupt energy level offset occurs in the other of said bands at said at least one heterojunction.
Claim 3
Dependent Claim
52 words
The heterojunction bipolar transistor of claim 1 wherein the collector layer and the emitter layer are both n-type and the base layer is p-type and wherein said abrupt energy level offset occurs in the valence band and wherein the conduction band energy levels are substantially aligned at said at least one heterojunction.
Claim 4
Dependent Claim
52 words
The heterojunction bipolar transistor of claim 1 wherein the collector layer and the emitter layer are both p-type and the base layer is n-type and wherein said abrupt energy level offset occurs in the conduction band and wherein the valence band energy levels are substantially aligned at said at least one heterojunction.
Claim 5
Dependent Claim
40 words
The heterojunction bipolar transistor of claim 2 or 3 wherein both the first and second junctions are between different semiconductor materials thereby forming first and second heterojunctions wherein the energy levels are aligned at both the first and second heterojunctions.
Claim 6
Dependent Claim
104 words
A heterojunction bipolar transistor comprising: a collector layer of a first conductivity type; a base layer of a second conductivity type forming a first heterojunction with said collector layer; and an emitter layer of the first conductivity type forming a second heterojunction with said base layer; the semiconductor materials of each of said collector, base and emitter layers having conduction and valence band energy levels wherein each of the energy levels of one of said bands are substantially aligned at the first and second heterojunctions and an abrupt energy level offset occurs in the other of said bands at the first and second heterojunctions.
Claim 7
Dependent Claim
104 words
A heterojunction bipolar transistor comprising: a collector layer of a first conductivity type; a base layer of a second conductivity type forming a first heterojunction with said collector layer; and an emitter layer of the first conductivity type forming a second heterojunction with said base layer; the semiconductor materials of each of said collector, base and emitter layers having conduction and valence band energy levels wherein each of the energy levels of one of said bands are substantially aligned at the first and second heterojunctions and an abrupt energy level offset occurs in the other of said bands at the first and second heterojunctions.
Claim 8
Dependent Claim
52 words
The heterojunction bipolar transistor of claim 5 wherein the collector layer and the emitter layer are both n-type and the base layer is p-type and wherein said abrupt energy level offset occurs in the valence band and wherein the conduction band energy levels are substantially aligned at the first and second heterojunctions.
Claim 9
Dependent Claim
34 words
The heterojunction bipolar transistor of claim 6 wherein the semiconductor material forming the emitter and collector layers s a compound containing at least one element selected from the group consisting of Al and In.
Claim 10
Dependent Claim
20 words
The heterojunction bipolar transistor of claim 6 wherein the semiconductor material forming the base layer is a compound containing Ga.
Claim 11
Dependent Claim
35 words
The heterojunction bipolar transistor of claim 7 wherein the semiconductor material forming the emitter and collector layers is a compound including at least one element selected from the group consisting of P, As and Sb.
Claim 12
Dependent Claim
33 words
The heterojunction bipolar transistor of claim 8 wherein the semiconductor material forming the base layer is a compound including at least one element selected from the group consisting of P, As and Sb.
Claim 13
Dependent Claim
18 words
The heterojunction bipolar transistor of claim 6 wherein the valence band offset is approximately 0.4 eV or greater.
Claim 14
Dependent Claim
19 words
The heterojunction bipolar transistor of claim 11 wherein the emitter and collector contain InP and the base contains GaAsSb.
Claim 15
Dependent Claim
24 words
The heterojunction bipolar transistor of claim 12 wherein the emitter and collector contain InP and the base contains GaAs 0 .53 Sb 0 .47.
Claim 16
Dependent Claim
19 words
The heterojunction bipolar transistor of claim 11 wherein the emitter and collector contain InAlAs and the base contain GaAsSb.
Claim 17
Dependent Claim
30 words
The heterojunction bipolar transistor of claim 14 wherein the emitter and collector contain In 0 .69 Al 0 .31 As and the base contain GaAs 0 .38 Sb 0 .62.
Claim 18
Dependent Claim
19 words
The heterojunction bipolar transistor of claim 11 wherein the emitter and collector contain InAlAsSb and the base contain GaSb.
Claim 19
Dependent Claim
25 words
The heterojunction bipolar transistor of claim 16 wherein the emitter and collector contain In 0 .55 Al 0 .45 As 0 .55 Sb 0 .45.
Claim 20
Dependent Claim
19 words
The heterojunction bipolar transistor of claim 11 wherein the emitter and collector contain InAlP, and the base contain GaAsP.
Claim 21
Dependent Claim
30 words
The heterojunction bipolar transistor of claim 18 wherein the emitter and collector contain In 0 .33 Al 0 .67 P, and the base contain GaAs 0 .69 P 0 .31.
Claim 22
Dependent Claim
44 words
The heterojunction bipolar transistor of claim 11 wherein the collector layer is a multi-region layer containing a first region of n + -type doping and a second region of n-type doping and the base layer is a single region of p + -type doping.
Claim 23
Dependent Claim
49 words
The heterojunction bipolar transistor of claim 20 wherein the n + -type regions have a doping concentration of approximately 5×10 18 , n-type regions have a doping concentration of approximately 10 17 , and the p + -type region having a doping concentration approximately 10 19 cm -3 .
Claim 24
Dependent Claim
23 words
The heterojunction bipolar transistor of claim 21 wherein each of the n, n + and p + regions are approximately 100 nm wide.
Claim 25
Dependent Claim
21 words
The heterojunction bipolar transistor of claim 9 or 10 wherein the compounds for the emitter, collector and base are lattice matched.
Claim 26
Dependent Claim
21 words
The heterojunction bipolar transistor of claim 9 or 10 wherein the compounds for the emitter, collector and base are random alloys.
Claim 27
Dependent Claim
25 words
The heterojunction bipolar transistor of claim 9 or 10 wherein the emitter and collector are formed of a superlattice structure of two binary compound semiconductors.
Claim 28
Dependent Claim
17 words
The heterojunction bipolar transistor of claim 25 wherein the superlattice structure is grown in an MBE system.
Claim 29
Dependent Claim
20 words
The heterojunction bipolar transistor of claim 23 wherein the emitter, base and collector are formed on a lattice matched substrate.
Claim 30
Dependent Claim
26 words
The heterojunction bipolar transistor of claim 9 or 10 wherein the substrate is GaAs and the emitter and collector is InGaP and the base is GaAlAs.
Claim 31
Dependent Claim
31 words
The heterojunction bipolar transistor of claim 28 wherein the emitter and collector is In 0 .48 Ga 0 .52 P and the base is Ga 0 .87 Al 0 .13 As.
Claim 32
Dependent Claim
20 words
The heterojunction bipolar transistor of claim 29 wherein the emitter, base and collector is lattice matched to a GaAs substrate.
Claim 33
Dependent Claim
52 words
The heterojunction bipolar transistor of claim 5 wherein the collector layer and the emitter layer are both p-type and the base layer is n-type and wherein the abrupt energy level offset occurs in the conduction band and wherein the valence band energy levels are substantially aligned at the first and second heterojunctions.
Claim 34
Dependent Claim
18 words
The heterojunction bipolar transistor of claim 31 wherein the conduction band offset is approximately 0.4 eV or greater.
Claim 35
Dependent Claim
19 words
The heterojunction bipolar transistor of claim 32 wherein the base is InP and the emitter and collector are AlAsSb.
Claim 36
Dependent Claim
16 words
The heterojunction bipolar transistor of claim 33 wherein the conduction band offset is approximately 0.6 eV.
Claim 37
Dependent Claim
99 words
A semiconductor structure comprising: an emitter layer, a collector layer and a base layer sandwiched between said emitter and collector layers, the emitter, base and collector layers being formed from semiconductor materials thereby forming at least one heterojunction, the semiconductor materials of each of the emitter, base and collector layers having conduction and valence band energy levels wherein the energy levels of one of said bands are substantially equal in the layers forming the at least one heterojunction and an energy level offset between the layers forming the at least one heterojunction occurs in the other of said bands.
Claim 38
Dependent Claim
99 words
A semiconductor structure comprising: an emitter layer, a collector layer and a base layer sandwiched between said emitter and collector layers, the emitter, base and collector layers being formed from semiconductor materials thereby forming at least one heterojunction, the semiconductor materials of each of the emitter, base and collector layers having conduction and valence band energy levels wherein the energy levels of one of said bands are substantially equal in the layers forming the at least one heterojunction and an energy level offset between the layers forming the at least one heterojunction occurs in the other of said bands.
Claim 39
Dependent Claim
46 words
The semiconductor structure of claim 35 wherein two heterojunctions are formed and wherein the energy levels in each of said layers are substantially equal in one of said bands and energy level offsets occur between the layers forming the heterojunctions in the other of said bands.
Claim 40
Dependent Claim
29 words
The semiconductor structure of claim 35 or 36 wherein the energy levels are substantially equal in the conduction band and the energy level offsets are in the valence band.
Claim 41
Dependent Claim
29 words
The semiconductor structure of claim 35 or 36 wherein the energy levels are substantially equal in the valence band and the energy level offsets are in the conduction band.
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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) | 1992-04-10 | 1992-10-10 | 1993-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-10 | 1996-10-10 | 1997-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-10 | 2000-10-10 | 2001-04-11 | $7700.00 | Window Closed / Lapsed |