EP0278386A2
Expired / Lapsed
EP
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Heterojunction bipolar Transistor
Assignee: NTT Inc
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Filing: 1988-02-04
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Granted: —
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Expires: 2008-02-04
Abstract
Abstract A heterojunction bipolar transistor includes an emitter layer (11) of a first conductivity type, a base layer (12) of a second conductivity type adjacent to the emitter layer, a collector buffer layer (13) of the first conductivity type, and a collector layer (14, 15) arranged between the collector buffer layer and the base layer. The collector layer includes a first collector layer (14) formed at the side of the base layer and a second collector layer (15) arranged at the side of the collector buffer layer. The first collector layer is a semiconductor layer having an impurity concentration lower than that of the base layer. The second collector layer is a semiconductor layer of the second conductivity type having an impurity concentration higher than that of the first collector layer.
Inventors
- 👤 Tadao Nippon Telegr. And Teleph. Corp. Ishibashi
- 👤 Yoshiki Nippon Telegr. And Teleph. Corp. Yamauchi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 03:47
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/60; H10D10/00; H10D10/80; H10D10/821; H10D62/10; H10D62/13; H10D62/137
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
133 words
A heterojunction bipolar transistor comprising: an emitter layer (11;21;31;41) of a first conductivity type; a base layer (12;22;32;42) of a second conductivity type adjacent to said emitter layer; a collector buffer layer (13;26;35;45) of the first conductivity type; and a collector layer (14,15;24,25;33,34;43,44) arranged between said collector buffer layer and said base layer, characterised in that said collector layer includes a first collector layer (14;24;33;43) formed at the side of said base layer and a second collector layer (15;25;34;44) arranged at the side of said collector buffer layer, said first collector layer is a semiconductor layer having an impurity concentration lower than that of said base layer, and said second collector layer is a semiconductor layer of the second conductivity type having an impurity concentration higher than that of said first collector layer.
Claim 2
Dependent Claim
133 words
A heterojunction bipolar transistor comprising: an emitter layer (11;21;31;41) of a first conductivity type; a base layer (12;22;32;42) of a second conductivity type adjacent to said emitter layer; a collector buffer layer (13;26;35;45) of the first conductivity type; and a collector layer (14,15;24,25;33,34;43,44) arranged between said collector buffer layer and said base layer, characterised in that said collector layer includes a first collector layer (14;24;33;43) formed at the side of said base layer and a second collector layer (15;25;34;44) arranged at the side of said collector buffer layer, said first collector layer is a semiconductor layer having an impurity concentration lower than that of said base layer, and said second collector layer is a semiconductor layer of the second conductivity type having an impurity concentration higher than that of said first collector layer.
Claim 3
Dependent Claim
46 words
A transistor according to claim 1, wherein the semiconductor layer of said first collector layer is constituted by a layer selected from the group consisting of a semiconductor layer of the first conductivity type, a semiconductor of the second conductivity type, and a semi-insulating semiconductor layer.
Claim 4
Dependent Claim
19 words
A transistor according to claim 1, wherein said first and second collector layers are depleted in an operating state.
Claim 5
Dependent Claim
16 words
A transistor according to claim 1, wherein said collector buffer layer is a collector electrode layer.
Claim 6
Dependent Claim
31 words
A transistor according to claim 1, wherein said first collector layer contains an impurity of the first conductivity type, thereby compensating for a space charge produced by free carriers injected-upon operation.
Claim 7
Dependent Claim
41 words
A transistor according to claim 1, further comprising a third collector layer between said base layer and said first collector layer, wherein said third collector layer is formed to have an impurity concentration higher than that of said first collector layer.
Claim 8
Dependent Claim
185 words
A heterojunction bipolar transistor comprising: an emitter layer of a first conductivity type; a base layer of a second conductivity type adjacent to said emitter layer; a collector buffer layer of the first conductivity type; and a collector layer arranged between said collector buffer layer and said base layer, characterised in that said collector layer includes a first collector layer (14;24;33;43) formed at the side of said base layer (12;22;32;42) and a second collector layer (15;25;34;44) arranged at the side of said collector buffer layer (13;26;35;45), said first collector layer is formed to have an impurity concentration lower than that of said collector buffet layer, a band gap energy of which is formed in a predetermined distribution from said base layer to said collector buffer layer, said second collector layer is formed to have an impurity concentration of the second conductivity type higher than that of said first collector layer, a band gap energy of which is incremented from said first collector layer to said collector buffer layer, and said collector buffer has a band gap energy larger than that of said first collector layer.
Claim 9
Dependent Claim
185 words
A heterojunction bipolar transistor comprising: an emitter layer of a first conductivity type; a base layer of a second conductivity type adjacent to said emitter layer; a collector buffer layer of the first conductivity type; and a collector layer arranged between said collector buffer layer and said base layer, characterised in that said collector layer includes a first collector layer (14;24;33;43) formed at the side of said base layer (12;22;32;42) and a second collector layer (15;25;34;44) arranged at the side of said collector buffer layer (13;26;35;45), said first collector layer is formed to have an impurity concentration lower than that of said collector buffet layer, a band gap energy of which is formed in a predetermined distribution from said base layer to said collector buffer layer, said second collector layer is formed to have an impurity concentration of the second conductivity type higher than that of said first collector layer, a band gap energy of which is incremented from said first collector layer to said collector buffer layer, and said collector buffer has a band gap energy larger than that of said first collector layer.
Claim 10
Dependent Claim
18 words
A transistor according to claim 7, wherein the band gap energy of said first collector layer is constant.
Claim 11
Dependent Claim
27 words
A transistor according to claim 7, wherein the band gap energy of said first collector layer is incremented from said base layer to said collector buffer layer.
Claim 12
Dependent Claim
40 words
A transistor according to claim 9, wherein distribution of the band gap energy of said first collector layer and distribution of the band gap energy of said second collector layer form a pattern which is gradually incremented as a whole.
Claim 13
Dependent Claim
33 words
A transistor according to claim 7, wherein at least part of said first collector layer, all of the second collector layer, and part of the collector buffer layer form a space charge layer.
Claim 14
Dependent Claim
47 words
A transistor according to claim 7, wherein a semiconductor layer of said first collector layer is constituted by a layer selected from the group consisting of a semiconductor layer of the first conductivity type, a semiconductor layer of the second conductivity type, and a semi-insulating semiconductor layer.
References Cited (Backward Citations)
No citation records indexed.
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