US4933728A — Semiconductor optical device

Claim 1

Independent Claim 176 words

A semiconductor optical device comprising: a substrate; semiconductor layers formed on said substrate including a first semiconductor layer which has a first forbidden band energy gap, and a second semiconductor layer which has a second forbidden band energy gap; a third relatively thin layer being formed between said first and second semiconductor layers and having a third forbidden band energy gap which is larger than both of said first and second forbidden band energy gaps, wherein said third layer has a thickness which is sufficiently thin so that electrons and positive holes in said first and second semiconductor layers through said third layer form excitons as a result of having an overlapping of wave functions of the electrons and the positive holes; and means for controlling probability of tunneling recombination of the electrons and the positive holes which form excitons through the third layer and including a pair of electrodes one of which being coupled to said first semiconductor layer and the other one of said pair of electrodes being coupled to said second semiconductor layer.

Claim 2

Dependent Claim 176 words

A semiconductor optical device comprising: a substrate; semiconductor layers formed on said substrate including a first semiconductor layer which has a first forbidden band energy gap, and a second semiconductor layer which has a second forbidden band energy gap; a third relatively thin layer being formed between said first and second semiconductor layers and having a third forbidden band energy gap which is larger than both of said first and second forbidden band energy gaps, wherein said third layer has a thickness which is sufficiently thin so that electrons and positive holes in said first and second semiconductor layers through said third layer form excitons as a result of having an overlapping of wave functions of the electrons and the positive holes; and means for controlling probability of tunneling recombination of the electrons and the positive holes which form excitons through the third layer and including a pair of electrodes one of which being coupled to said first semiconductor layer and the other one of said pair of electrodes being coupled to said second semiconductor layer.

Claim 3

Dependent Claim 67 words

A semiconductor optical device as set forth in claim 1, characterized in that a probability T of the tunneling recombination of the electrons and positive holes, in which the thickness D (Å) and the height H (eV) of the barrier constructing said third layer is expressed by T=exp [-0.4 D√ H], falls within a range of 0.6 to 1×10 -10 in the state having no voltage applied.

Claim 4

Dependent Claim 132 words

A semiconductor optical device as set forth in claim 1, or 2, characterized in that an overlap of wave functions of the electrons and the positive holes through said third layer is made larger than an overlap of the wave functions of the electrons and the positive holes within each one of said first and second semiconductor layers by making the thicknesses of said first and second semiconductor layers not smaller than 200 Å thereby resulting in pushing said electrons and said positive holes of said first and second semiconductor layers to the third layer by the respective composition of the crystal structure of said first and second semiconductor layers, of doped impurity in the crystal of said first and second semiconductor layers, or by a pseudopotential established by an external field.

Claim 5

Dependent Claim 26 words

A semiconductor optical device as set forth in claim 1, characterized in that said third layer is made of a semiconductor of a direct transition type.

Claim 6

Dependent Claim 29 words

A semiconductor optical device as set forth in claim 1, characterized in that said third layer has a thickness ranging from that of a monoatomic layer to 100 Å.

Claim 7

Dependent Claim 24 words

A semiconductor optical device as set forth in claim 1, characterized in that said third layer has a thickness not greater than 100 Å.

Claim 8

Dependent Claim 93 words

A semiconductor optical device as set forth in claim 1, characterized by having means for applying an electric field in a direction normal to said third layer to said first and second semiconductor layers opposed to each other through said third layer to collect said electrons at an interface between a first main surface of said third layer and one of said first and second semiconductor layers and said positive holes at an interface between a second main surface of said third layer and the other of said first and second semiconductor layers.

Claim 9

Dependent Claim 57 words

A semiconductor optical device as set forth in claim 1, characterized in that the composition and/or impurity density of one or both of said first and second semiconductor layers are made nonuniform in the direction of the thickness of said third layer to collect said electrons and said positive holes in the vicinity of said third layer.

Claim 10

Dependent Claim 60 words

A semiconductor optical device as set forth in claim 1, characterized in that a layered structure constructed of at least said third layer and said first and second semiconductor layers is sandwiched between third and fourth semiconductor layers which have a larger forbidden band energy gap than said first and second semiconductor layers and which have different types of conductivity.

Claim 11

Dependent Claim 58 words

A semiconductor optical device as set forth in claim 1, characterized in that said third layer is made of Ga 1-x Al x As, said first semiconductor layer is made of Ga 1-y Al y As, and said second semiconductor layer is made of Ga 1-z A z As, wherein: x>y and z; 1≧x>0.1; and 0.4>y and z≧0.

Claim 12

Dependent Claim 53 words

A semiconductor optical device as set forth in claim 1, characterized in that said third layer is made of Ga x In 1-x P y As 1-y (which holds even for x=0 and y=0), and said first and second semiconductor layers are made of Ga m In 1-m P x As 1-x .

Claim 13

Dependent Claim 104 words

A semiconductor optical device comprising: a first semiconductor layer having a first narrow forbidden energy band, a second semiconductor layer having a second narrow forbidden energy band, a third layer being formed between the first and the second semiconductor layer and having a third forbidden energy band which is wider than said first and said second narrow energy band so as to provide an alignment of electrons in one of said first and second semiconductor layers and holes in the other of said first and second semiconductor layers to effect Bose condensation, and means for controlling probability of recombination of said electrons and holes.

Claim 14

Dependent Claim 104 words

A semiconductor optical device comprising: a first semiconductor layer having a first narrow forbidden energy band, a second semiconductor layer having a second narrow forbidden energy band, a third layer being formed between the first and the second semiconductor layer and having a third forbidden energy band which is wider than said first and said second narrow energy band so as to provide an alignment of electrons in one of said first and second semiconductor layers and holes in the other of said first and second semiconductor layers to effect Bose condensation, and means for controlling probability of recombination of said electrons and holes.

Claim 15

Dependent Claim 139 words

A semiconductor optical device according to claim 12, characterized in that an overlap of wave functions of the electrons and the positive holes through said third layer is made larger than an overlap of the wave functions of the electrons and the positive holes within each one of said first and second semiconductor layers by making the thicknesses of said first and second semiconductor layers not smaller than 200 Å thereby resulting in pushing said electrons and said positive holes of said first and second semiconductor layers to the third layer, the degree of movement toward the third layer being controlled by the respective composition of the crystal structure of said first and second semiconductor layers, of doped impurity distribution in the crystal of said first and second semiconductor layers, or by a pseudo-potential established by an external field.

Claim 16

Dependent Claim 24 words

A semiconductor optical device according to claim 13, characterized in that said third layer is made of a semiconductor of a direct transition type.

Claim 17

Dependent Claim 27 words

A semiconductor optical device according to claim 14, characterized in that said third layer has a thickness ranging from that of a monoatomic layer to 100 Å.

Claim 18

Dependent Claim 27 words

A semiconductor optical device according to claim 13, characterized in that said third layer has a thickness ranging from that of a monoatomic layer to 100 Å.

Claim 19

Dependent Claim 22 words

A semiconductor optical device according to claim 14, characterized in that said third layer has a thickness not larger than 100 Å.

Claim 20

Dependent Claim 22 words

A semiconductor optical device according to claim 13, characterized in that said third layer has a thickness not larger than 100 Å.

Claim 21

Dependent Claim 52 words

A semiconductor optical device according to claim 12, wherein said first and second semiconductor layers are comprised of material with a molecular composition crystal structure of component elements therein which are nonuniformly ratioed and/or impurity doping concentration which is nonuniformly distributed in the direction corresponding to the thickness of said crystal structure.

Claim 22

Dependent Claim 134 words

A semiconductor optical device according to claim 12, further comprising: a semiconductor substrate of a first conductivity type, wherein there is formed thereon on a first principal surface thereof, as a vertically stacked arrangement, a mesa-stripe type semiconductor laser, in the following order: a first cladding layer, an undoped first GaAs layer corresponding to said first semiconductor layer, a barrier layer corresponding to said third layer, an undoped second GaAs layer corresponding to said second semiconductor layer, a second cladding layer, a semiconductor cap layer of a second complementary conductivity type, and wherein there is further included a pair of electrodes, one being formed on a second principal surface of said semiconductor substrate and the other one being formed on said semiconductor cap layer which is an upper surface of said vertically stacked arrangement.

Claim 23

Dependent Claim 32 words

A semiconductor optical device according to claim 20, wherein said first and second cladding layers are semiconductor layers which have a wider forbidden band energy than said first and second GaAs layers.

Claim 24

Dependent Claim 56 words

A semiconductor optical device according to claim 21, wherein said barrier layer is a Ga 1-x Al x As semiconductor layer, said first cladding layer is a Ga 1-y Al y As semiconductor layer, and said second cladding layer is a Ga 1-z Al z As semiconductor layer, wherein x>y and z, 1≧x>0.1, y<0.4, and z≧0.

Claim 25

Dependent Claim 37 words

A semiconductor optical device according to claim 22, wherein said Ga 1-x Al x As semiconductor barrier layer, said Ga 1-y Al y As and said Ga 1-z Al z As semiconductor layers are undoped semiconductor layers.

Claim 26

Dependent Claim 34 words

A semiconductor optical device according to claim 23, wherein said barrier layer has a thickness of about 30 Å and said first and second undoped GaAs layer have a thickness of about 0.1 μm.

Claim 27

Dependent Claim 23 words

A semiconductor optical device according to claim 24, wherein said first and second semiconductor cladding layers have a thickness of about 2 μm.

Claim 28

Dependent Claim 45 words

A semiconductor optical device according to claim 25, wherein said semiconductor cap layer is a p-type GaAs layer having a thickness less than said cladding layers and greater than said first and second undoped GaAs layers, and said semiconductor substrate is an n-type GaAs substrate.

Claim 29

Dependent Claim 17 words

A semiconductor optical device according to claim 26, wherein said cap layer thickness is about 0.2 μm.

Claim 30

Dependent Claim 51 words

A semiconductor optical device according to claim 27, wherein there is further included a buffer layer formed on said first principal surface of said semiconductor substrate and which corresponds to a semiconductor layer disposed between said semiconductor substrate and the lowermost layer of the mesa which is said first cladding layer.

Claim 31

Dependent Claim 24 words

A semiconductor optical device according to claim 28, wherein said buffer layer is an n-type GaAs layer having a thickness of about 0.5 μm.

Claim 32

Dependent Claim 51 words

A semiconductor optical device according to claim 20, wherein there is further included a buffer layer formed on said first principal surface of said semiconductor substrate and which corresponds to a semiconductor layer disposed between said semiconductor substrate and the lowermost layer of the mesa which is said first cladding layer.

Claim 33

Dependent Claim 32 words

A semiconductor optical device according to claim 30, wherein said first and second cladding layers are semiconductor layers which have a wider forbidden band energy than said first and second GaAs layers.

Claim 34

Dependent Claim 56 words

A semiconductor optical device according to claim 31, wherein said barrier layer is a Ga 1-x Al x As semiconductor layer, said first cladding layer is a Ga 1-y Al y As semiconductor layer, and said second cladding layer is a Ga 1-z Al z As semiconductor layer, wherein x>y and z, 1≧x>0.1, y<0.4, and z≧0.

Claim 35

Dependent Claim 56 words

A semiconductor optical device according to claim 30, wherein said barrier layer is a Ga 1-x Al x As semiconductor layer, said first cladding layer is a Ga 1-y Al y As semiconductor layer, and said second cladding layer is a Ga 1-z Al z As semiconductor layer, wherein x>y and z, 1≧x>0.1, y<0.4, and z≧0.

Claim 36

Dependent Claim 37 words

A semiconductor optical device according to claim 33, wherein said Ga 1-x Al x As semiconductor barrier layer, said Ga 1-y Al y As and said Ga 1-z Al z As semiconductor layers are undoped semiconductor layers.

Claim 37

Dependent Claim 20 words

A semiconductor optical device according to claim 29, wherein said buffer layer and said vertically stacked arrangement are epitaxial layers.

Claim 38

Dependent Claim 48 words

A semiconductor optical device according to claim 29, wherein said mesa vertically stacked layer arrangement is embedded in a further semiconductor layer having an upper surface which is planar with the upper surface of said mesa layer arrangement, whereby there is effected a buried heterostructure type semiconductor laser.

Claim 39

Dependent Claim 144 words

A semiconductor optical device according to claim 12, further comprising: a semiconductor substrate of a first conductivity type, wherein there is formed on a first principal surface thereof, as a vertically stacked arrangement, in the following order: a buffer layer of said first conductivity type, a first cladding semiconductor layer of said first conductivity type, a first active semiconductor layer corresponding to said first semiconductor layer, a thin barrier layer corresponding to said third layer, a second active semiconductor layer corresponding to said second semiconductor layer, a second cladding semiconductor layer of a second complementary conductivity type, a semiconductor cap layer of said second conductivity type, and wherein there is further included a pair of electrodes, one being formed on a second principal surface of said semiconductor substrate and the other one being formed on said semiconductor cap layer, thereby effecting a semiconductor laser.

Claim 40

Dependent Claim 96 words

A semiconductor optical device according to claim 37, wherein said thin barrier layer has a thickness of less than 100 Å, said first and second active semiconductor layers being undoped GaAs active layers, said first and second cladding semiconductor layers are an n-type Ga 0 .7 Al 0 .3 As layer and a p-type Ga 0 .7 Al 0 .3 As layer, respectively, said buffer layer is an n-type GaAs/Ga 0 .7 Al 0 .3 As super-lattice buffer layer, said substrate an n-type GaAs semiconductor substrate and said cap layer is a p-type GaAs semiconductor layer.

Claim 41

Dependent Claim 82 words

A semiconductor optical device according to claim 38, wherein said thin barrier layer has a thickness of about 30 Å and is an undoped AlAs layer, said first and second active layers have a thickness of about 0.1 μm, said first cladding layer has a thickness of about 2 μm, said second cladding layer has a thickness of about 1.5 μm, said cap layer has a thickness of about 0.2 μm, and said buffer layer has a thickness of about 1 μm.

Claim 42

Dependent Claim 50 words

A semiconductor optical device according to claim 37, wherein said thin barrier layer is a Ga x In 1-x P y As 1-y layer, which is inclusive of x=0 and y=0, and wherein said first and second active semiconductor layers are Ga m In 1-m P x As 1-x layers.

Claim 43

Dependent Claim 82 words

A semiconductor optical device according to claim 40, wherein said thin barrier layer has a thickness of about 30 Å and is an undoped AlAs layer, said first and second active layers have a thickness of about 0.1 μm, said first cladding layer has a thickness of about 2 μm, said second cladding layer has a thickness of about 1.5 μm, said cap layer has a thickness of about 0.2 μm, and said buffer layer has a thickness of about 1 μm.

Claim 44

Dependent Claim 52 words

A semiconductor optical device according to claim 37, wherein said first and second semiconductor layers are comprised of material with a molecular composition crystal structure of component elements therein which are nonuniformly ratioed and/or impurity doping concentration which is nonuniformly distributed in the direction corresponding to the thickness of said third layer.

Claim 45

Dependent Claim 59 words

A semiconductor optical device comprising: a stacked arrangement of semiconductor layers; and means for controlling probability of tunnel recombination of electrons and holes existing in different semiconductor layers of said stacked arrangement, the electrons and the holes form excitons subjected to Bose condensation so that the emissions obtained from the excitons have a high density and a coherent phase.

Claim 46

Dependent Claim 59 words

A semiconductor optical device comprising: a stacked arrangement of semiconductor layers; and means for controlling probability of tunnel recombination of electrons and holes existing in different semiconductor layers of said stacked arrangement, the electrons and the holes form excitons subjected to Bose condensation so that the emissions obtained from the excitons have a high density and a coherent phase.

Claim 47

Dependent Claim 66 words

A semiconductor optical device according to claim 43, wherein said electrons and holes which form respective excitons correspond to first and second active semiconductor layers, having a first and a second forbidden energy band, respectively, of said stacked arrangement and which have interposed therebetween a thin barrier layer having a third forbidden energy band which is greater than said first and said second forbidden energy band.

Claim 48

Dependent Claim 51 words

A semiconductor optical device according to claim 44, wherein said first and second semiconductor active layers, together with said interposed thin barrier layer, are interposed between first surfaces of third and fourth cladding semiconductor layers, which have a greater forbidden energy band than that of said first and second active layers.

Claim 49

Dependent Claim 89 words

A semiconductor optical device according to claim 45, further including a cap semiconductor layer of one conductivity type formed on a second opposing surface of said second cladding layer, a semiconductor substrate and a semiconductor buffer layer, the latter interposed between a first principal surface of said semiconductor substrate and a second opposing surface of said first cladding layer, wherein said cap semiconductor layer and said semiconductor substrate have formed thereon, on opposing surfaces, electrodes, said semiconductor substrate and said buffer layer being of a second complementary conductivity type.

Claim 50

Dependent Claim 56 words

A semiconductor optical device according to claim 46, wherein said barrier layer is a Ga 1-x Al x As semiconductor layer, said first cladding layer is a Ga 1-y Al y As semiconductor layer, and said second cladding layer is a Ga 1-z Al z As semiconductor layer, wherein x>y and z, 1≧x>0.1, y<0.4, and z≧0.

Claim 51

Dependent Claim 127 words

A semiconductor optical device according to claim 47, wherein said Ga 1-x Al x As semiconductor barrier layer, said Ga 1-y Al y As and said Ga 1-z Al z As semiconductor layers are undoped semiconductor layers, said barrier layer has a thickness of about 30 Å, said first and second undoped GaAs layer have a thickness of about 0.1 μm, said first and second semiconductor cladding layers have a thickness of about 2 μm, said semiconductor cap layer is a p-type GaAs layer having a thickness less than said cladding layers and greater than said first and second undoped GaAs layers, said semiconductor substrate is an n-type GaAs substrate, and wherein said buffer layer is an n-type GaAs layer having a thickness of about 0.5 μm.

Claim 52

Dependent Claim 96 words

A semiconductor optical device according to clain 43, wherein said thin barrier layer has a thickness of less than 100 Å, said first and second active semiconductor layers being undoped GaAs active layers, said first and second cladding semiconductor layers are an n-type Ga 0 .7 Al 0 .3 As layer and a p-type Ga 0 .7 Al 0 .3 As layer, respectively, said buffer layer is an n-type GaAs/Ga 0 .7 Al 0 .3 As super-lattice buffer layer, said substrate an n-type GaAs semiconductor substrate and said cap layer is a p-type GaAs semiconductor layer.

Claim 53

Dependent Claim 96 words

A semiconductor optical device according to clain 43, wherein said thin barrier layer has a thickness of less than 100 Å, said first and second active semiconductor layers being undoped GaAs active layers, said first and second cladding semiconductor layers are an n-type Ga 0 .7 Al 0 .3 As layer and a p-type Ga 0 .7 Al 0 .3 As layer, respectively, said buffer layer is an n-type GaAs/Ga 0 .7 Al 0 .3 As super-lattice buffer layer, said substrate an n-type GaAs semiconductor substrate and said cap layer is a p-type GaAs semiconductor layer.

Claim 54

Dependent Claim 82 words

A semiconductor optical device according to claim 49, wherein said thin barrier layer has a thickness of about 30 Å and is an undoped AlAs layer, said first and second active layers have a thickness of about 0.1 μm, said first cladding layer has a thickness of about 2 μm, said second cladding layer has a thickness of about 1.5 μm, said cap layer has a thickness of about 0.2 μm, and said buffer layer has a thickness of about 1 μm.

Claim 55

Dependent Claim 50 words

A semiconductor optical device according to claim 45, wherein said thin barrier layer is a Ga x In 1-x P y As 1-y layer, which is inclusive of x=0 and y=0, and wherein said first and second active semiconductor layers are Ga m In 1-m P x As 1-x layers.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-06-11	1993-12-11	1994-06-12	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-06-11	1997-12-11	1998-06-12	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-06-11	2001-12-11	2002-06-12	$7700.00	Window Closed / Lapsed

Semiconductor optical device

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