US4684969A
Expired / Lapsed
US
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Heterojunction avalanche photodiode
Assignee: NEC Corp
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Filing: 1984-07-09
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Granted: 1987-08-04
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Expires: 2004-07-09
Abstract
Abstract An avalanche photodiode comprising an uppermost layer of one conductivity type, a second layer of the other conductivity type wherein the electrons or hole having the greater ionization rate are the minority carriers, a third layer of the second type, having a smaller bandgap than the second layer and wherein the electrons or holes having the greater ionization rate are the majority carriers, and a multi-layer heterojunction structure between the second and third layers comprising alternate layers of the second conductivity type having a bandgap as large as the second layer and layers having a bandgap between those of the second and third layers.
Inventors
- 👤 Kenko Taguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:49
CPC Classifications
B; B82; B82Y; B82Y20/00; H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/222; H10F30/225; H10F30/2255; H10F77/00; H10F77/10; H10F77/14; H10F77/146
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
198 words
An avalanche photodiode comprising: a substrate of a first conductivity type; a first semiconductor layer of a first conductivity type having a greater ionization rate for minority carriers than for majority carriers, said first semiconductor layer being formed over said substrate; a second semiconductor layer of said first conductivity type, having a smaller bandgap than said first layer to provide an absorption region; a multi-heterojunction structure positioned between said first and second semiconductor layers and comprising, alternately laid one over the other, semiconductor layers of said first conductivity type and having a bandgap not smaller than that of said first semiconductor layer, and fourth semiconductor layers having a bandgap not smaller than that of said second semiconductor layer but not larger than that of said first semiconductor layer, said multi-heterojunction structure enhancing an ionization rate of minority carriers greater than that of said majority carriers due to a band edge discontinuity; a semiconductor region of a second conductivity type formed within said first semiconductor layer to provide a PN junction separated from the multi-heterojunction structure; and a pair of electrodes disposed over said substrate and said semiconductor layer of the second conductivity type, for biasing said PN junction.
Claim 2
Dependent Claim
198 words
An avalanche photodiode comprising: a substrate of a first conductivity type; a first semiconductor layer of a first conductivity type having a greater ionization rate for minority carriers than for majority carriers, said first semiconductor layer being formed over said substrate; a second semiconductor layer of said first conductivity type, having a smaller bandgap than said first layer to provide an absorption region; a multi-heterojunction structure positioned between said first and second semiconductor layers and comprising, alternately laid one over the other, semiconductor layers of said first conductivity type and having a bandgap not smaller than that of said first semiconductor layer, and fourth semiconductor layers having a bandgap not smaller than that of said second semiconductor layer but not larger than that of said first semiconductor layer, said multi-heterojunction structure enhancing an ionization rate of minority carriers greater than that of said majority carriers due to a band edge discontinuity; a semiconductor region of a second conductivity type formed within said first semiconductor layer to provide a PN junction separated from the multi-heterojunction structure; and a pair of electrodes disposed over said substrate and said semiconductor layer of the second conductivity type, for biasing said PN junction.
Claim 3
Dependent Claim
45 words
An avalanche photodiode, as recited in claim 1; wherein said first conductivity type is n-type; wherein said first and third semiconductor layers are composed of InP; wherein said second semiconductor layer is composed of InGaAs; and wherein said fourth semiconductor layer is composed of InGaAs.
Claim 4
Dependent Claim
25 words
An avalanche photodiode, as recited in claim 1, further comprising a contact electrode layer of the second conductivity type for contacting the second semiconductor layer.
Claim 5
Dependent Claim
212 words
An avalanche photodiode comprising: a substrate of a first conductivity type; a first semiconductor layer of n-type conductivity and having a greater ionization rate for holes than for electrons to provide an avalanche region, said first semiconductor layer being formed over said substrate; a second semiconductor layer of said n-type conductivity, having a smaller bandgap than said first layer and having a greaer ionization rate for electrons than for holes to provide an absorption region; a multi-heterojunction structure positioned between said first and second semiconductor layers and comprising, alternately laid one over the other, third semiconductor layers of said n-type conductivity and having a bandgap not smaller than that of said first semiconductor layer, and fourth semiconductor layers of said n-type conductivity and having a bandgap not smaller than that of said second semiconductor layer but not larger than that of said first semiconductor layer, said multi-heterojunction structure enhancing an ionization rate for holes greater than that for electrons due to the valence band edge discontinuity; a semiconductor region of a p-type conductivity formed within said first semiconductor layer to provide a PN junction separated from the multi-heterojunction structure; and a pair of electrodes, disposed over said substrate and said semiconductor layer of the second conductivity type, for biasing said PN junction.
Claim 6
Dependent Claim
212 words
An avalanche photodiode comprising: a substrate of a first conductivity type; a first semiconductor layer of n-type conductivity and having a greater ionization rate for holes than for electrons to provide an avalanche region, said first semiconductor layer being formed over said substrate; a second semiconductor layer of said n-type conductivity, having a smaller bandgap than said first layer and having a greaer ionization rate for electrons than for holes to provide an absorption region; a multi-heterojunction structure positioned between said first and second semiconductor layers and comprising, alternately laid one over the other, third semiconductor layers of said n-type conductivity and having a bandgap not smaller than that of said first semiconductor layer, and fourth semiconductor layers of said n-type conductivity and having a bandgap not smaller than that of said second semiconductor layer but not larger than that of said first semiconductor layer, said multi-heterojunction structure enhancing an ionization rate for holes greater than that for electrons due to the valence band edge discontinuity; a semiconductor region of a p-type conductivity formed within said first semiconductor layer to provide a PN junction separated from the multi-heterojunction structure; and a pair of electrodes, disposed over said substrate and said semiconductor layer of the second conductivity type, for biasing said PN junction.
References Cited (Backward Citations)
GB2107927A
Cited
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