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US4933732A
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Heterojunction bipolar transistor
Assignee: Toshiba Corp
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Filing: 1988-06-30
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Granted: 1990-06-12
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Expires: 2008-06-30
Abstract
Abstract A heterojunction bipolar transistor comprises a first semiconductor layer of a first conductivity type, a second semiconductor layer of the first conductivity type formed on the first semiconductor layer, a third semiconductor layer of a second conductivity type formed on the second semiconductor layer, the first, second and third semiconductor layers serving as a collector, a fourth semiconductor layer of the second conductivity type formed on the third semiconductor layer, the fourth semiconductor layer serving as a base, and a fifth semiconductor layer of the first conductivity type formed on the fourth semiconductor layer, the fifth semiconductor layer serving as an emitter, the fourth and fifth semiconductor layers together forming a heterojunction, and the fifth semiconductor layer having a larger band gap than the fourth semiconductor layer, wherein the first, second, third and fourth semiconductor layers are related as follows: ##EQU1## where N 1 , N 2 , N 3 , and N 4 are impurity concentrations of the first, second, third, and fourth semiconductor layers, respectively, e is the unit charge, ε is the dielectric constant of the collector, V bi is the built-in potential between the second and third semiconductor layers, and W 3 is the thickness of the third semiconductor layer.
Inventors
- 👤 Riichi Katoh
- 👤 Mamoru Kurata
- 👤 Kouhei Morizuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:11
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/80; H10D10/821
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
204 words
A heterojunction bipolar transistor comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on said first semiconductor layer; a third semiconductor layer of a second conductivity type formed on said second semiconductor layer, said first, second and third semiconductor layers serving as a collector; a fourth semiconductor layer of said second conductivity type formed on said third semiconductor layer, said fourth semiconductor layer serving as a base; and a fifth semiconductor layer of the first conductivity type formed on said fourth semiconductor layer, said fifth semiconductor layer serving as an emitter, said fourth and fifth semiconductor layers together forming a heterojunction, and said fifth semiconductor layer having a larger band gap than said fourth semiconductor layer; wherein said first, second, third and fourth semiconductor layers are related as follows: ##EQU5## where N 1 , N 2 , N 3 , and N 4 are impurity concentrations of said first, second, third, and fourth semiconductor layers, respectively, e is the unit charge, ε is the dielectric constant of said collector, V bi is the built-in potential between said second and third semiconductor layers, and W 3 is the thickness of said third semiconductor layer.
Claim 2
Dependent Claim
204 words
A heterojunction bipolar transistor comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on said first semiconductor layer; a third semiconductor layer of a second conductivity type formed on said second semiconductor layer, said first, second and third semiconductor layers serving as a collector; a fourth semiconductor layer of said second conductivity type formed on said third semiconductor layer, said fourth semiconductor layer serving as a base; and a fifth semiconductor layer of the first conductivity type formed on said fourth semiconductor layer, said fifth semiconductor layer serving as an emitter, said fourth and fifth semiconductor layers together forming a heterojunction, and said fifth semiconductor layer having a larger band gap than said fourth semiconductor layer; wherein said first, second, third and fourth semiconductor layers are related as follows: ##EQU5## where N 1 , N 2 , N 3 , and N 4 are impurity concentrations of said first, second, third, and fourth semiconductor layers, respectively, e is the unit charge, ε is the dielectric constant of said collector, V bi is the built-in potential between said second and third semiconductor layers, and W 3 is the thickness of said third semiconductor layer.
Claim 3
Dependent Claim
34 words
A transistor according to claim 1, wherein the impurity concentration N 3 of said third semiconductor layer decreases from the side of said fourth semiconductor layer toward the side of said second semiconductor layer.
Claim 4
Dependent Claim
255 words
A heterojunction bipolar transistor comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on said first semiconductor layer; a third semiconductor layer of a second conductivity type formed on said second semiconductor layer, said first, second and third semiconductor layers serving as a collector; a fourth semiconductor layer of the second conductivity type formed on said third semiconductor layer, said fourth semiconductor layer having an intrinsic base region serving as a base, and an external base region formed to surround said intrinsic base region; and a fifth semiconductor layer of the first conductivity type formed on said fourth semiconductor layer, said fifth semiconductor layer serving as an emitter, said fourth and fifth semiconductor layers together forming a heterojunction, and said fifth semiconductor layer having a larger band gap than said fourth semiconductor layer; wherein said second and third semiconductor layers formed below the external base region are formed to have high resistivity; and wherein said first, second, third and fourth semiconductor layers are related as follows: ##EQU6## W 2 >W 3 where N 1 , N 2 , N 3 , and N 4 are impurity concentrations of said first, second, third, and fourth semiconductor layers, respectively, e is the unit charge, ε is the dielectric constant of said collector, V bi is the built-in potential between said second and third semiconductor layers, W 2 is the thickness of said second semiconductor layer, and W 3 is the thickness of said third semiconductor layer.
Claim 5
Dependent Claim
255 words
A heterojunction bipolar transistor comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on said first semiconductor layer; a third semiconductor layer of a second conductivity type formed on said second semiconductor layer, said first, second and third semiconductor layers serving as a collector; a fourth semiconductor layer of the second conductivity type formed on said third semiconductor layer, said fourth semiconductor layer having an intrinsic base region serving as a base, and an external base region formed to surround said intrinsic base region; and a fifth semiconductor layer of the first conductivity type formed on said fourth semiconductor layer, said fifth semiconductor layer serving as an emitter, said fourth and fifth semiconductor layers together forming a heterojunction, and said fifth semiconductor layer having a larger band gap than said fourth semiconductor layer; wherein said second and third semiconductor layers formed below the external base region are formed to have high resistivity; and wherein said first, second, third and fourth semiconductor layers are related as follows: ##EQU6## W 2 >W 3 where N 1 , N 2 , N 3 , and N 4 are impurity concentrations of said first, second, third, and fourth semiconductor layers, respectively, e is the unit charge, ε is the dielectric constant of said collector, V bi is the built-in potential between said second and third semiconductor layers, W 2 is the thickness of said second semiconductor layer, and W 3 is the thickness of said third semiconductor layer.
Claim 6
Dependent Claim
34 words
A transistor according to claim 3, wherein the impurity concentration N 3 of said third semiconductor layer decreases from the side of said fourth semiconductor layer toward the side of said second semiconductor layer.
Claim 7
Dependent Claim
178 words
A heterojunction bipolar transistor comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on said first semiconductor layer; a third undoped semiconductor layer formed on said second semiconductor layer; a fourth semiconductor layer of a second conductivity type formed on said third semiconductor layer, said first, second, third and fourth semiconductor layers serving as a collector; a fifth semiconductor layer of the second conductivity type formed on said fourth semiconductor layer, said fifth semiconductor layer serving as a base; and a sixth semiconductor layer of the first conductivity type formed on said fifth semiconductor layer, said fifth and sixth semiconductor layers together forming a heterojunction, and said sixth semiconductor layer having a larger band ga than said fifth semiconductor layer; wherein said first, second, fourth and fifth semiconductor layers are related as follows: N 1 >N 2 N 4 <N 5 where N 1 , N 2 , N 4 , and N 5 are impurity concentrations of said first, second, fourth, and fifth semiconductor layers, respectively.
Claim 8
Dependent Claim
178 words
A heterojunction bipolar transistor comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on said first semiconductor layer; a third undoped semiconductor layer formed on said second semiconductor layer; a fourth semiconductor layer of a second conductivity type formed on said third semiconductor layer, said first, second, third and fourth semiconductor layers serving as a collector; a fifth semiconductor layer of the second conductivity type formed on said fourth semiconductor layer, said fifth semiconductor layer serving as a base; and a sixth semiconductor layer of the first conductivity type formed on said fifth semiconductor layer, said fifth and sixth semiconductor layers together forming a heterojunction, and said sixth semiconductor layer having a larger band ga than said fifth semiconductor layer; wherein said first, second, fourth and fifth semiconductor layers are related as follows: N 1 >N 2 N 4 <N 5 where N 1 , N 2 , N 4 , and N 5 are impurity concentrations of said first, second, fourth, and fifth semiconductor layers, respectively.
Claim 9
Dependent Claim
34 words
A transistor according to claim 5, wherein the impurity concentration N 4 of said fourth semiconductor layer decreases from the side of said fifth semiconductor layer toward the side of said third semiconductor layer.
References Cited (Backward Citations)
US4750025A
Cited
US4593305A
Cited
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