US4881235A
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Semiconductor laser having a multiple quantum well structure doped with impurities
Assignee: Hitachi Ltd
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Filing: 1987-04-23
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Granted: 1989-11-14
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Expires: 2007-04-23
Abstract
Abstract In a well-known semiconductor laser, a multiple quantum well type active layer consisting of barrier layers and active layers or well layers, each of which has a thickness less than the de Broglie wavelength of electrons, is doped with an impurity, and the impurity density is made higher in the barrier layer than in the well layer. Further, in a case where the multiple quantum well active layer is held between p-type and n-type cladding layers, the well layer is undoped, the part of the barrier layer lying in contact with the well layer is undoped, and the other part of the barrier layer close to the p-type cladding layer is put into the n-conductivity type while that of the barrier layer close to the n-type cladding layer is put into the n-conductivity type. Desirably, the impurity density should range from about 1×10 18 to about 1×10 19 cm - 3.
Inventors
- 👤 Naoki Chinone
- 👤 Kazuhisa Uomi
- 👤 Tadashi Fukuzawa
- 👤 Hideaki Matsueda
- 👤 Takashi Kajimura
- 👤 Tsukuru Ohtoshi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:47
CPC Classifications
B; B82; B82Y; B82Y20/00; H; H01; H01S; H01S5/00; H01S5/30; H01S5/34; H01S5/20; H01S5/22; H01S5/227; H01S5/2275; H01S5/305; H01S5/3086; H01S5/309; H01S5/3407; Y; Y10; Y10S; Y10S372/00; Y10S372/704
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
145 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers formed on the substrate, the plurality of semiconductor layers including a cladding layer, at least one active layer and at least one barrier layer, the at least one active layer and at least one barrier layer being stacked alternately so as to form a multiple quantum well structure and together forming an active region, and a resonant cavity including said active region, wherein the at least one active layer respectively has a thickness that is smaller than a wave packet of free electrons within a crystal, and wherein the active region has a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being larger than 10 18 cm -3 ; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 2
Dependent Claim
145 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers formed on the substrate, the plurality of semiconductor layers including a cladding layer, at least one active layer and at least one barrier layer, the at least one active layer and at least one barrier layer being stacked alternately so as to form a multiple quantum well structure and together forming an active region, and a resonant cavity including said active region, wherein the at least one active layer respectively has a thickness that is smaller than a wave packet of free electrons within a crystal, and wherein the active region has a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being larger than 10 18 cm -3 ; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 3
Dependent Claim
30 words
A semiconductor laser according to claim 1, wherein the impurity density of said at least one barrier layer is made higher than that of said at least one active layer.
Claim 4
Dependent Claim
29 words
A semiconductor laser according to claim 1, wherein said at least one active layer is undoped, and said at least one barrier layer has an n- or p-conductivity type.
Claim 5
Dependent Claim
32 words
A semiconductor laser according to claim 1, wherein said at least one active layer is undoped, and a part of the at least one barrier layer has an n- or p-conductivity type.
Claim 6
Dependent Claim
13 words
A semiconductor layer according to claim 1, wherein the impurities are p-type impurities.
Claim 7
Dependent Claim
13 words
A semiconductor laser according to claim 16, wherein the impurities are n-type impurities.
Claim 8
Dependent Claim
31 words
A semiconductor laser according to claim 1, wherein the impurities are of both p-type and n-type, with the p-type and n-type impurities respectively being doped in different sub-regions of said part.
Claim 9
Dependent Claim
19 words
A semiconductor laser according to claim 5, wherein the impurity concentration is greater than 4×10 18 cm -3 .
Claim 10
Dependent Claim
19 words
A semiconductor laser according to claim 6, wherein the impurity concentration is greater than 2×10 18 cm -3 .
Claim 11
Dependent Claim
19 words
A semiconductor laser according to claim 1, wherein the impurity concentration is at most 10 19 cm -3 .
Claim 12
Dependent Claim
22 words
A semiconductor laser according to claim 1, wherein the impurities are selected from the group consisting of Mg, Be, Si and Se.
Claim 13
Dependent Claim
20 words
A semiconductor laser according to claim 1, wherein the part doped with impurities is the at least one barrier layer.
Claim 14
Dependent Claim
38 words
A semiconductor laser according to claim 12, wherein each of the at least one barrier layers has a central portion and outer sandwiching portions, the central portion being doped with impurities and the outer sandwiching portions being undoped.
Claim 15
Dependent Claim
20 words
A semiconductor laser according to claim 1, wherein the part doped with impurities is the at least one active layer.
Claim 16
Dependent Claim
62 words
A semiconductor laser according to claim 1, wherein the plurality of semiconductor layers include a pair of cladding layers, with the pair of cladding layers on the sides of the active region so as to sandwich the active region therebetween, and further include a current confining layer on one of the cladding layers, on a side thereof not adjacent the active region.
Claim 17
Dependent Claim
57 words
A semiconductor laser according to claim 15, wherein the plurality of semiconductor layers further includes a further cladding layer on the current confining layer, with the current confining layer having a groove stripe therethrough, and the further cladding layer extending through the groove stripe to contact the cladding layer on which the current confining layer is positioned.
Claim 18
Dependent Claim
27 words
A semiconductor laser according to claim 16, wherein the cladding layer, on which the current confining layer is positioned, has a thickness of 0.1 to 0.7 μm.
Claim 19
Dependent Claim
52 words
A semiconductor laser according to claim 1, wherein the substrate is a semi-insulating semiconductor substrate, and wherein the plurality of semiconductor layers includes a first semiconductor layer doped with a high impurity concentration of a first conductivity type, with the cladding layer and active region being formed on said first semiconductor layer.
Claim 20
Dependent Claim
36 words
A semiconductor laser according to claim 18, wherein the plurality of semiconductor layers include a pair of cladding layers, sandwiching the active region, and a current confinement layer on the cladding layer on the active region.
Claim 21
Dependent Claim
107 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers forming a cladding layer and a multiple quantum well active region, the multiple quantum well active region providing a resonant cavity, the multiple quantum well active region being formed by at least one active layer and at least one barrier layer stacked alternately on each other, wherein the multiple quantum well active region has a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being larger than 10 18 cm -3 ; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 22
Dependent Claim
107 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers forming a cladding layer and a multiple quantum well active region, the multiple quantum well active region providing a resonant cavity, the multiple quantum well active region being formed by at least one active layer and at least one barrier layer stacked alternately on each other, wherein the multiple quantum well active region has a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being larger than 10 18 cm -3 ; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 23
Dependent Claim
193 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers formed on the substrate, the plurality of semiconductor layers including a multiple quantum well active region formed of at least one active layer and at least one barrier layer stacked alternately, and also including first conductivity type and second conductivity type cladding layers respectively sandwiching the multiple quantum well active region, the first and second conductivity types being opposite conductivity types to each other, the at least one active layer each having a thickness less than the de Broglie wavelength of electrons, the at least one barrier layer having a bandgap greater than that of the at least one active layer, the cladding layers having a bandgap larger than that of the at least one active layer, wherein the multiple quantum well active region has a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being greater than 10 18 cm -3 , and wherein the laser includes a resonant cavity including said multiple quantum well active region; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 24
Dependent Claim
193 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers formed on the substrate, the plurality of semiconductor layers including a multiple quantum well active region formed of at least one active layer and at least one barrier layer stacked alternately, and also including first conductivity type and second conductivity type cladding layers respectively sandwiching the multiple quantum well active region, the first and second conductivity types being opposite conductivity types to each other, the at least one active layer each having a thickness less than the de Broglie wavelength of electrons, the at least one barrier layer having a bandgap greater than that of the at least one active layer, the cladding layers having a bandgap larger than that of the at least one active layer, wherein the multiple quantum well active region has a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being greater than 10 18 cm -3 , and wherein the laser includes a resonant cavity including said multiple quantum well active region; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 25
Dependent Claim
31 words
A semiconductor laser according to claim 21, wherein the first conductivity type cladding layer is a p-type cladding layer and the second conductivity type cladding layer is an n-type cladding layer.
Claim 26
Dependent Claim
53 words
A semiconductor laser according to claim 22, wherein in said multiple quantum well active region, at least one set of active and barrier layers which are continuous in adjacency to said p-type cladding layer have the n-conductivity type, and the other region of said multiple quantum well active region has the p-conductivity type.
Claim 27
Dependent Claim
60 words
A semiconductor laser according to claim 22, wherein in said multiple quantum well active region, at least one barrier layer, which is continuous and adjacent to said p-type cladding layer, has the n-conductivity type, the barrier layers in the other region of said multiple quantum well active region have the p-conductivity type, and all of said active layers are undoped.
Claim 28
Dependent Claim
102 words
A semiconductor laser according to claim 22, wherein in said multiple quantum well active region, at least one barrier layer, which is continuous and adjacent to said p-type cladding layer, has the n-conductivity type, but at least one atom layer from an interface at which it lies in contact with an active layer is undoped; the barrier layers in the other region of said multiple quantum well active region have the p-conductivity type, but at least one atom layer from an interface at which it lies in contact with an active layer is undoped; and all of said active layers are undoped.
Claim 29
Dependent Claim
47 words
A semiconductor laser according to claim 21, wherein said barrier layer is undoped in at least one atom layer from an interface at which it lies in contact with said active layer and has the p-conductivity type in the other region, and said active layer is undoped.
Claim 30
Dependent Claim
21 words
A semicondcutor laser according to claim 21, wherein each active layer has a thickness of from 3 nm to 10 nm.
Claim 31
Dependent Claim
159 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers formed on said semiconductor substrate, the plurality of semiconductor layers including an active region and cladding layers sandwiching the active region, wherein the active region is a multiple quantum well structure including at least one active layer and at least one barrier layer alternately stacked one upon another, each of the active layers having a thickness smaller than the de Broglie wavelength, and each of the barrier layers having a forbidden band width greater than that of the active layers, the active region including a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being greater than 10 18 cm -3 , so as to decrease the threshold current for driving the semiconductor laser, the laser including a resonant cavity including said active region; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 32
Dependent Claim
159 words
A semiconductor laser comprising: a semiconductor substrate; a plurality of semiconductor layers formed on said semiconductor substrate, the plurality of semiconductor layers including an active region and cladding layers sandwiching the active region, wherein the active region is a multiple quantum well structure including at least one active layer and at least one barrier layer alternately stacked one upon another, each of the active layers having a thickness smaller than the de Broglie wavelength, and each of the barrier layers having a forbidden band width greater than that of the active layers, the active region including a light emitting portion in which there is a part doped with impurities, the impurity concentration thereof being greater than 10 18 cm -3 , so as to decrease the threshold current for driving the semiconductor laser, the laser including a resonant cavity including said active region; and a pair of electrodes for injecting carriers into the light emitting portion, to emit light.
Claim 33
Dependent Claim
14 words
A semiconductor laser according to claim 28, wherein the active region is a graded-index-separate-confinement-heterostructure.
Claim 34
Dependent Claim
77 words
A semiconductor laser according to claim 29, wherein the active region includes an active layer sandwiched by barrier layers, the active region being sandwiched by cladding layers, the cladding layers and active region being in the form of a stripe on the substrate, and wherein the plurality of semiconductor layers further includes two layers, of opposite conductivity type to each other, formed stacked one on the other on the semiconductor substrate, at the sides of the stipe.
Claim 35
Dependent Claim
28 words
A semiconductor laser according to claim 30, further comprising a zinc-diffused region formed at the top of the stripe, in the upper one of the two cladding layers.
Claim 36
Dependent Claim
31 words
A semiconductor laser according to claim 28, wherein at least one of said at least one barrier layer and said at least one active layer includes said part doped with impurities.
Claim 37
Dependent Claim
36 words
A semiconductor laser according to claim 32, wherein said part doped with impurities is doped with n-type impurities, the n-type impurities in the part having an impurity concentration of greater than 2×10 18 cm -3 .
Claim 38
Dependent Claim
36 words
A semiconductor laser according to claim 32, wherein said part doped with impurities is doped with p-type impurities, the p-type impurities in the part having an impurity concentration of greater than 4×10 18 cm -3 .
Claim 39
Dependent Claim
27 words
A semiconductor laser according to claim 34, wherein said p-type impurities consist of at least one selected from the group consisting of magnesium ions and beryllium ions.
Claim 40
Dependent Claim
57 words
A semiconductor laser according to claim 32, wherein said part doped with impurities is doped with both p-type and n-type impurities, the p-type impurities in said part having an impurity concentration of greater than 4×10 18 cm -3 , the n-type impurities in said part having an impurity concentration of greater than 2×10 18 cm -3 .
Claim 41
Dependent Claim
27 words
A semiconductor laser according to claim 36, wherein said n-type impurities consist of at least one selected from the group consisting of selenium ions and silicon ions.
Claim 42
Dependent Claim
22 words
A semiconductor laser according to claim 28, wherein the impurity concentration of said part is at most 10 19 cm -3 .
Claim 43
Dependent Claim
36 words
A semiconductor laser according to claim 28, wherein said part doped with impurities is doped with p-type impurities, the p-type impurities in the part having an impurity concentration of greater than 4×10 18 cm -3 .
Claim 44
Dependent Claim
36 words
A semiconductor laser according to claim 28, wherein said part doped with impurities is doped with n-type impurities, the n-type impurities in the part having an impurity concentration of greater than 2×10 18 cm -3 .
References Cited (Backward Citations)
US4132960A
Cited
US4573161A
Cited
US4512022A
Cited
US4644378A
Cited
US4599728A
Cited
US4644553A
Cited
US4706253A
Cited
US4701774A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-11-13 | 1993-05-15 | 1993-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-13 | 1997-05-15 | 1997-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-13 | 2001-05-15 | 2001-11-14 | $7700.00 | Window Closed / Lapsed |