JPH10321960A - Light-emitting semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting semiconductor element, capable of eliminating the inefficiency in current injection and a decrease in quantum efficiency for the semiconductor light-emitting element. SOLUTION: Semiconductor thin layers 11a, 12b are inserted to separate confinement heterostructure layers(SCH layers) 11, 12, the semiconductor thin layer 12a has a positive value with which the valence band discontinuity creates no barrier against holes and the conductive band discontinuity creates barrier against elements, and the semiconductor thin layer 11a is provided with a band construction creating a positive value in which a conductive band discontinuity creates no barrier against electrons but the valence band discontinuity creates a barrier against holes. Also, the valence band discontinuity between SCH layer 12 at p-type clad layer side and a clad layer 14 is constituted with a clad layer 14 which creates no barrier against holes, and the conductive band discontinuity between the SCH layer 11 at an n-type clad layer side and a clad layer 13 is constituted with the clad layer 13 which creates no barrier against electrons.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor light emitting device having high current injection efficiency and high quantum efficiency.

[0002]

2. Description of the Related Art In a conventional semiconductor light emitting device, conduction band discontinuity and valence band discontinuity are positive because electrons and holes as carriers are confined in a light emitting layer. A clad layer having a band structure such as a well has been used. For this reason, when a voltage is applied to the element and biasing is performed, barriers 21 and 22 for electrons and holes are generated as shown in FIG. 2 and the carrier injection efficiency is poor.

Accordingly, in some devices, a semiconductor gradient composition layer 31 for smoothing a band structure between a light emitting layer and a cladding layer as shown in FIG. A semiconductor layer 32 having an intermediate composition between the light emitting layer and the cladding layer is inserted to improve the injection efficiency, and at the same time, enhance the confinement of light in the light emitting layer.

[0004]

However, the insertion of such a gradient composition layer 31 or an intermediate composition semiconductor layer 32 makes the band structure almost smooth, but the carriers overflow from this area to the light emitting layer. However, there is a problem that carrier recombination occurs in these layers, and the quantum efficiency is greatly reduced particularly in a state of large current injection or a high temperature state.

[0005] Further, as shown in FIG. 3C, a structure has been proposed in which a carrier stopper layer is inserted in a semiconductor layer having an intermediate composition to suppress overflow of carriers from a light emitting layer (IE).
EE J. Quantum Electron., Vol. 31, pp. 423, 1995)
Since the carrier stopper layer also acts as a barrier against injected carriers, there are problems such as a decrease in injection efficiency and a large deterioration in efficiency during high current injection.

An object of the present invention is to provide a semiconductor light emitting device which can eliminate inefficiency of current injection and a decrease in quantum efficiency of the semiconductor light emitting device.

[0007]

According to the present invention, as shown in FIG. 1, a single or multiple quantum well structure sandwiched between separate confinement heterostructure layers (hereinafter abbreviated as SCH layers) 11, 12 is provided. In the semiconductor light emitting device having the light emitting layer 10 including the cladding layers 13 and 14 on both sides thereof,
The semiconductor thin layers 11 a and 12 a are inserted into the H layers 11 and 12.

Here, the semiconductor in the SCH layer 12 on the p-type layer side
The body thin layer 12a has a valence band discontinuity ΔE _VIs a barrier to holes
Almost zero, conduction band discontinuity ΔE_CBut
It has a positive value that acts as a barrier to electrons, and has n-type S
The semiconductor thin layer 11a in the CH layer 11 has a conduction band discontinuity ΔE_C
Is almost zero and has no valence
Subband discontinuity ΔE_VHas a positive value that is a barrier to holes
A band structure as shown in FIG.

As an example of a crystal system for forming such a band structure, InGaAlAs / InGaAsP is used.
System. FIG. 11 schematically shows a band diagram in the case of lattice matching with the InP substrate. In the figure, (c) is the one when the band gap is the largest, and has a staggered band structure. On the other hand, in FIG. 11A, the InAlAs side is used as InGaAlAs, and the minimum band gap In
The time when it became GaAs is shown. In FIG. 11 (c), the conduction band of InAlAs is a barrier to InP, but in FIG. 11 (a), InP is a barrier to InGaAs, and therefore, there is a middle point between them. Composition In
There is a state diagram (b) in GaAlAs where ΔE _c図 0. This is an example in which InP is fixed. Even when InP is set to InGaAsP in a certain composition range, InGaAlAa which similarly becomes ΔE _c ０0 exists. On the other hand, FIG.
The side where InGaAsP is used and the time when InGaAs with the minimum band gap is reached is shown. In FIG. 11C, InP is a barrier against InAlAs in the valence band, whereas in FIG. 11E, InAlAs is more in InGa.
As a barrier to As, there is a phase diagram 11 (d) of ΔE _vの 0 for InGaAsP of some composition in between. This is an example where InAlAs is fixed,
Even if InAlAs is a certain composition range of InGaAlAs, InGaAsP which similarly becomes ΔE _v 〜0 exists. By combining such material compositions, the constituent features of the present invention can be constituted.

Further, the valence band discontinuity between the SCH layer 12 and the cladding layer 14 on the p-type cladding layer side does not become a barrier to holes, and becomes almost zero. The structure is such that the conduction band discontinuity between the layer 11 and the cladding layer 13 does not act as a barrier to electrons and is almost zero. It is different from the conventional technique in that there is almost no hindrance to carrier injection, high carrier injection efficiency can be obtained up to a high current state, and only carriers are confined in the light emitting layer to obtain high quantum efficiency.

[Operation] In the present invention, the SCH layers 11, 12
The semiconductor thin film layers 11a and 12a are inserted therein, and SC
Semiconductor thin film layers 11a and 12a having compositions in which conduction band discontinuity ΔE _C or valence band discontinuity ΔE _V becomes almost zero with respect to injected carriers are used for H layers 11 and 12, and SCH layer 1 is used.
By making the conduction band discontinuity or the valence band discontinuity almost zero with respect to the injected carriers between the first and second cladding layers 13 and 14, there is no potential barrier that hinders the passage of carriers. Carriers are smoothly and efficiently injected into the light emitting layer up to the current region, and at the same time, only the carriers are confined in the light emitting layer, so that high quantum efficiency and high light output can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 4 shows a semiconductor light emitting device according to a first embodiment of the present invention, and FIG. 5 schematically shows a band diagram in a bias state. In the figure, 41 is n-InP cladding layer, 42 InGaAlAs (E _g ~1.1eV composition) separate confinement heterostructure (SCH) layer, 4
3 is an InGaAlAs / InGaAlAs multiple quantum well light emitting layer (λ _PL １．５1.55 μm), 44 is an InAlAs electron stopper layer, 45 is an InGaAsP (E _g １．１1.1 eV composition) separate confinement heterostructure (SCH) layer,
46 is a p-InAlAs clad layer, 47 is a p-doped InGaAs / InGaAlAs gradient composition contact layer,
8, 49 are n and p electrodes, respectively.

In this embodiment, InGaAsP is used as the SCH layer 45 near the p-side cladding layer 46, and the SCH layer 4
5, the valence band discontinuity ΔE _V of the InAlAs electron stopper layer 44 does not act as a barrier to holes, becomes almost zero, and the conduction band discontinuity ΔE _C acts as a barrier to electrons. The InGaAsP composition was chosen to have.
Also, InAlAs is used for the p-type cladding layer 46, and SC
The valence band discontinuity between the H layer 45 and the cladding layer 46 is also prevented from acting as a barrier to holes.

As a result, in this embodiment, there is no barrier against injected holes, and holes are efficiently injected into the light emitting layer 43. At the same time, since the conduction band discontinuity ΔE _C is large, electrons in the p-side SCH layer 45 are removed. Leakage is extremely reduced, and light is emitted efficiently. The electron stopper layer 44 may have a thickness of about several tens of nanometers at which electron tunneling does not occur. In this embodiment, the thickness is set to 20 nm.

FIG. 6 shows a band diagram of a conventional structure as a comparative example.
Shown in In the figure, 63 is a light emitting layer, 62 and 64 are SCH layers, and 61 and 65 are cladding layers. In the conventional device, the hole injection efficiency is not good because there is a barrier due to ΔE _v with respect to the hole injection as shown in FIG. In addition, since the electrons injected into the light emitting layer 63 also leak into the SCH layer 64, there is recombination of light emission and non-light emission at this portion, and the quantum efficiency is reduced.

As described above, in this embodiment, as compared with the prior art shown in FIG. 6, the carrier injection efficiency is improved, and the confinement of carriers in the light emitting layer 43 is improved, so that the quantum efficiency is increased. The oscillation threshold value in the case of using a laser having a ridge width of 3 μm is also 20 mA, compared to 30 mA of a conventional device having a layer structure.
The following values were obtained: In addition, since the carrier injection efficiency is maintained high even in the high current region, an optical output of 100 mW or more was obtained, and the threshold and efficiency temperature characteristics were also improved.

This embodiment is an example of a ridge laser.
Similar effects can be obtained by various structures such as an embedded structure. This embodiment is an example, and the light emitting layer is made of InGaAs.
P / InGaAsP multiple quantum well light emitting layer, InGaAsP / I
nGaAlAs multiple quantum well light emitting layer (well layer is made of InGaAsP
However, it is needless to say that InGaAlAs may be used) or a single quantum well.

However, when the quantum well barrier layer is made of InGaAsP, the n-side SCH layer is also made of InGaAsP.
It is necessary to form a smooth band structure between the layer and the cladding layer by the gradient composition layer. Needless to say, the emission wavelength may be changed by changing the composition or structure of the light emitting layer. In addition, even if the composition of the p-side InGaAsPSCH layer is changed, the electron stopper layer is changed to the In-type.
The composition may be adjusted as GaAlAs.

At this time, the cladding layer may be made of InGaAlAs, or may be smoothly connected to InAlAs by a gradient composition layer. It is needless to say that the same effect can be obtained even if a lattice strain is applied to the multiple quantum well layer, the SCH layer, and the stopper layer if the band structure according to the gist of the present invention is configured. Further, the valence band discontinuity does not have to be completely zero, and the valence band discontinuity is several tens me corresponding to thermal energy.
Similar results can be obtained with about V. The SCH layer is not limited to a single composition, but may have a stepped composition, a pseudo gradient composition, or a gradient composition.

Embodiment 2 FIG. 7 shows a semiconductor light emitting device according to a second embodiment of the present invention, and FIG. 8 schematically shows a band diagram in a bias state. In the figure, 71 is n-I
The nP cladding layer 72 is made of InGaAlAs (E _g １．１1.1 eV).
Composition) Separate confinement heterostructure (SC
H) layer, 73 is an InP hole stopper layer, 74 is InGa
AlAs / InGaAlAs multiple quantum well light emitting layer (λ _PL -1.
55 μm) and 75 are InGaAlAs (E _g １．１1.1 eV composition) separate confinement heterostructure (SC
H) layer, 76 InGaAlAs (E _g ~1.1eV composition)
, InAlAs is a graded composition layer, 77 is a p-InAlAs cladding layer, and 78 is a p-doped InGaAs / InGaAl.
As graded composition contact layers, 79 and 710 are each n
And a p-electrode.

In this embodiment, InGaAlAs is used as the SCH layer 72 near the n-side cladding layer 71, and the SCH layer 7
Conduction band discontinuity ΔE _C of the InP hole stopper layer 73 in FIG.
Does not become a barrier to electrons, almost zero,
The composition of InGaAlAs was selected such that the valence band discontinuity ΔE _V had a positive value serving as a barrier to holes. InP is also used for the n-type cladding layer 71 and the SCH layer 7 is formed.
The conduction band discontinuity between the layer 2 and the cladding layer 71 does not act as a barrier to electrons.

As a result, in the present embodiment, there is no barrier against injected electrons, and electrons are efficiently injected into the light emitting layer. At the same time, the valence band discontinuity ΔE _V is large, so that the number of holes n
Leakage into the side SCH is extremely reduced, and light is emitted efficiently. Note that the hole stopper layer 73 only needs to be about several tens of nm in which the tunnel effect of holes does not occur.
It was set to 0 nm.

In the conventional device, as shown in FIG. 6, the efficiency of electron injection is not good because there is a barrier caused by ΔE _C with respect to electron injection. In addition, since holes also leak into the SCH layer 62, light-emission and non-light-emission recombination exist in this portion, and the quantum efficiency is reduced. As described above, in this embodiment, as compared with the prior art shown in FIG. 6, the efficiency of carrier injection is improved, and the confinement of carriers in the light emitting layer 74 is improved, so that the quantum efficiency is increased and the ridge width is 3 μm. The lasing threshold is 30 m compared with the conventional device with a layered structure.
For A, a value of 24 mA or less was obtained.

In addition, since the carrier injection efficiency is maintained high even in a high current region, an optical output of 100 mW or more was obtained, and the threshold and efficiency temperature characteristics were also improved. Although the present embodiment is an example of a ridge laser, the same effect can be obtained with various element structures such as an embedded structure. This embodiment is an example, and the light emitting layer is made of InGaAsP /
InGaAsP multiple quantum well light emitting layer, InGaAsP / InGa
It is needless to say that the light emitting layer may be an AlAs multiple quantum well light emitting layer (the well layer may be InGaAsP or InGaAlAs) or a single quantum well.

However, when the quantum well barrier layer is made of InGaAsP, the p-side SCH layer is made of InGaAsP, the cladding layer is made of InP, and a smooth band structure is formed between the SCH layer and the cladding layer by a gradient composition layer. There is. Needless to say, the emission wavelength may be changed by changing the composition or structure of the light emitting layer. Also, the n-side In
Even if the composition of the GaAlAsSCH layer is changed, the composition may be adjusted accordingly by using the hole stopper layer as InGaAsP.

At this time, the cladding layer may be made of InGaAsP or a graded composition layer may be connected smoothly to InP. It is needless to say that the same effect can be obtained even if a lattice strain is applied to the multiple quantum well layer, the SCH layer, and the stopper layer if the band structure according to the gist of the present invention is configured. Further, the conduction band discontinuity does not have to be completely zero, and similar results can be obtained even when the conduction band discontinuity is about several tens meV corresponding to thermal energy.

The SCH layer is not limited to a single composition, but may have a stepped composition, a pseudo gradient composition or a gradient composition. It is needless to say that the same effects can be obtained by forming a band structure in accordance with the gist of the present invention also in a material such as InGaAsSb or another material based on which a similar band structure can be obtained instead of the InGaAlAs light emitting layer or the SCH layer. No.

Embodiment 3 FIG. 9 shows a semiconductor light emitting device according to a third embodiment of the present invention, and FIG. 10 schematically shows a band diagram in a bias state. In the figure, 91 is n-
InP cladding layer, 92 InGaAlAs (E _g ~1.1e
V composition) Separate confinement heterostructure (S
CH) layer, 93 is an InP hole stopper layer, 94 is InG
aAlAs / InGaAlAs multiple quantum well light emitting layer (λ _PL ~
1.55 μm), 95 is an InAlAs electron stopper layer,
96 InGaAsP (E _g ~1.1eV composition) separate confinement heterostructure (SCH) layer, 97 p
-InAlAs cladding layer, 98 is p-doped InGa
As / InGaAlAs graded composition contact layer, 99, 91
0 is an n and p electrode, respectively.

In this embodiment, InGaAsP is used as the SCH layer 96 near the p-side cladding layer 97, and the SCH layer 9 is used.
6, the valence band discontinuity ΔE _V of the InAlAs electron stopper layer 95 does not act as a barrier to holes, becomes almost zero, and the conduction band discontinuity ΔE _C acts as a barrier to electrons. The InGaAsP composition was chosen to have.
Also, InAlAs is used for the p-type cladding layer 97, and SC
The valence band discontinuity between the H layer 96 and the cladding layer 97 is also prevented from acting as a barrier to holes.

As a result, the barrier against injected holes is eliminated, and holes are efficiently injected into the light emitting layer. At the same time, since the conduction band discontinuity ΔE _C is large, leakage of electrons into the p-side SCH is extremely reduced. Further, InGaAlAs is used as the SCH layer 92 near the n-side cladding layer 91, and the conduction band discontinuity Δ of the InP hole stopper layer 93 in the SCH layer 92.
The composition of InGaAlAs was selected such that E _C did not act as a barrier to electrons, was almost zero, and the valence band discontinuity ΔE _V had a positive value acting as a barrier to holes.

Also, InP is used for the n-type cladding layer 91 so that the conduction band discontinuity between the SCH layer 92 and the cladding layer 91 does not become a barrier to electrons. As a result, there is no barrier against injected electrons, and electrons are efficiently injected into the light emitting layer. At the same time, since the valence band discontinuity ΔE _V is large, leakage of holes into the n-side SCH is extremely reduced, and light is efficiently emitted. The electron and hole stopper layers 95 and 93 need only have a thickness of about several tens of nanometers at which the tunnel effect of electrons and holes does not occur. In this embodiment, the thickness is set to 20 nm.

In the conventional device, as shown in FIG. 6, there is a barrier caused by ΔE _C and ΔE _v with respect to the carrier injection, so that the carrier injection efficiency is not good. The light emitting layer 63
Since the carriers injected into the side also leak to the SCH layers 62 and 64, there is recombination of light emission and non-light emission at this portion, and the quantum efficiency is reduced. As described above, in the present embodiment, as compared with the prior art shown in FIG. 6, the carrier injection efficiency is improved, and the confinement of the carriers in the light emitting layer is improved, so that the quantum efficiency is increased. The lasing threshold when using a laser is also 30 mA of that of a device with a conventional layer structure.
, A value of 17 mA or less was obtained.

Further, since the carrier injection efficiency is maintained high even in the high current region, an optical output of 100 mW or more was obtained, and the threshold and efficiency temperature characteristics were also improved. Although the present embodiment is an example of a ridge laser, the same effect can be obtained with various element structures such as an embedded structure. This embodiment is an example, and the light emitting layer is made of InGaAsP /
InGaAsP multiple quantum well light emitting layer, InGaAsP / InGa
It is needless to say that the light emitting layer may be an AlAs multiple quantum well light emitting layer (the well layer may be InGaAsP or InGaAlAs) or a single quantum well.

It goes without saying that the emission wavelength may be changed by changing the composition or structure of the light emitting layer.
Further, the composition of the p-side InGaAsPSCH layer and the n-side InGaAlAl
Even if the composition of the sSCH layer is changed, the electron stopper layer is made of InGaAlAs, and the hole stopper layer is made of InGaAlAs.
What is necessary is just to adjust the composition as GaAsP. At this time,
The cladding layers may be made of InGaAlAs and InGaAsP, respectively, or may be smoothly connected to InAlAs and InP by a gradient composition layer.

At this time, it is needless to say that the same effect can be obtained even if the lattice strain is added to the multiple quantum well layer, the SCH layer, and the stopper layer, if the band structure according to the gist of the present invention is formed. Further, the conduction band discontinuity and the valence band discontinuity with respect to the injected carrier need not be completely zero, and similar results can be obtained even when each of them has about several tens meV corresponding to thermal energy.

The SCH layer is not limited to a single composition, but may have a stepped composition, a pseudo gradient composition or a gradient composition. In addition, an InGaAlAs light emitting layer or an InGaAlAsSCH
InGaAsSb that can obtain a similar band structure instead of a layer
It is needless to say that the same effect can be obtained by forming a band structure in accordance with the gist of the present invention also in such a material and other material systems.

[0037]

As described above in detail with reference to the embodiments, according to the present invention, a semiconductor thin film is inserted into an SCH layer adjacent to a light emitting layer, and the material of the semiconductor thin film and the SCH layer and the cladding layer are inserted. By appropriately selecting the composition and forming a band structure so that it does not act as a barrier to injected carriers but a large barrier to carriers at the opposite electrode, carrier injection can be smoothly performed up to the high current region, and light emission can be further improved. Light emitting and non-light emitting recombination in layers other than the layers are suppressed, and a semiconductor light emitting device with high efficiency and high light output can be realized.

[Brief description of the drawings]

FIG. 1 is a band structure diagram of a semiconductor light emitting device according to the present invention.

FIG. 2 is a band structure diagram when a conventional semiconductor light emitting device is biased by applying a voltage.

FIG. 3A is a band diagram in a flat band state of a structure in which a semiconductor grading layer for smoothing the band structure is inserted between a light emitting layer and a cladding layer;
(B) is a band diagram in a flat band state of a structure in which a semiconductor layer having an intermediate composition between the light emitting layer and the cladding layer is inserted between the light emitting layer and the cladding layer, and FIG. FIG. 4 is a band diagram in a flat band state having a structure in which a semiconductor layer having an intermediate composition between a light emitting layer and a cladding layer and a carrier stopper layer are inserted.

FIG. 4 is an explanatory diagram of the first embodiment of the present invention.

FIG. 5 is a schematic band diagram of the device according to the first embodiment of the present invention in a bias state.

FIG. 6 is a band diagram of an element having a conventional structure in a bias state.

FIG. 7 is an explanatory diagram of a second embodiment of the present invention.

FIG. 8 is a schematic band diagram of a device according to a second embodiment of the present invention in a bias state.

FIG. 9 is an explanatory diagram of a third embodiment of the present invention.

FIG. 10 is a schematic band diagram of a device according to a third embodiment of the present invention in a bias state.

FIG. 11 is a band diagram schematically showing a case where lattice matching is performed with an InP substrate.

[Explanation of symbols]

Reference Signs List 41 n-InP cladding layer 42 InGaAlAs separate confinement heterostructure (SCH) layer 43 InGaAlAs / InGaAlAs multiple quantum well light emitting layer 44 InAlAs electron stopper layer 45 InGaAsP separate confinement heterostructure (SCH) Al p cladding layer 46A-p Highly doped InGaAs / InGaAlAs graded composition contact layers 48, 49n and p electrode 71 n-InP cladding layer 72 InGaAlAs separate confinement heterostructure (SCH) layer 73 InP hole stopper layer 74 InGaAlAs / InGaAlAs multiple quantum wells InA of InGaAlAs separate confinement heterostructure (SCH) layer 76 InGaAlAs (E _g ~1.1eV composition)
Gradient composition layer to lAs 77 p-InAlAs cladding layer 78 p heavily doped InGaAs / InGaAlAs gradient composition contact layer, 79,710 n and p electrode 91 n-InP cladding layer 92 InGaAlAs separate confinement heterostructure (SCH) layer 93 InP hole stopper layer 94 InGaAlAs / InGaAlAs multiple quantum well light emitting layer 95 InAlAs electron stopper layer 96 InGaAsP separate refinement heterostructure (SCH) layer 97 p-InAlAs cladding layer 98p heavily doped InGaAs layer AsInAlAsAlAs layer 910 n and p electrodes

Claims (6)

[Claims] 1. A semiconductor having a light emitting layer including a single or multiple quantum well structure sandwiched between separate confinement heterostructure layers of a single composition, a stepwise composition, a pseudo gradient composition, or a gradient composition, and a cladding layer on both sides thereof. In the light emitting device, the valence band discontinuity with respect to the p-type cladding layer side is almost zero, which does not act as a barrier for holes, and the conduction band discontinuity is caused by electrons from the light emitting layer. Insert a semiconductor thin film having a positive value as a barrier to
And a valence band discontinuity between the structural layer and the cladding layer on the p-type cladding layer side is almost zero, which does not act as a barrier to holes. 2. A semiconductor having a light emitting layer including a single or multiple quantum well structure sandwiched between separate confinement heterostructure layers of a single composition, a stepwise composition, a pseudo gradient composition, or a gradient composition, and a cladding layer on both sides thereof. In the light-emitting device, in the structure layer on the n-type cladding layer side, a conduction band discontinuity with respect to the structure layer does not act as a barrier to electrons, is almost zero, and a valence band discontinuity is a hole from the light-emitting layer. Insert a semiconductor thin film having a positive value as a barrier to
In addition, the semiconductor light emitting device is characterized in that the conduction band discontinuity between the structural layer on the n-type cladding layer side and the cladding layer does not act as a barrier to electrons and is almost zero. 3. A light emitting layer having a single or multiple quantum well structure sandwiched between separate confinement heterostructure layers of a single composition, a stepwise composition, a pseudo gradient composition, or a gradient composition, and a semiconductor having cladding layers on both sides thereof. In the light emitting device, the valence band discontinuity with respect to the p-type cladding layer side is almost zero, which does not act as a barrier for holes, and the conduction band discontinuity is caused by electrons from the light emitting layer. Insert a semiconductor thin film having a positive value as a barrier to
Furthermore, in the structure layer on the side of the n-type cladding layer, the conduction band discontinuity does not act as a barrier to electrons, is almost zero, and the valence band discontinuity acts as a barrier to holes from the light emitting layer. And the valence band discontinuity between the structural layer and the cladding layer on the p-type cladding layer side does not act as a barrier to holes, and is almost zero. A semiconductor light emitting device, wherein the conduction band discontinuity between the structural layer and the cladding layer on the layer side is almost zero, which does not act as a barrier to electrons. 4. An InGaAsP or InGaAlAs light-emitting layer or InGaAlAs / InGaAlAs, InGaAsP / InGa sandwiched between separate confinement heterostructure layers of a single composition, a stepwise composition, a pseudogradient composition, or a gradient composition.
In a semiconductor light emitting device having a single or multiple quantum well structure light emitting layer of AsP or InGaAlAs / InGaAsP and a cladding layer on both sides thereof, the structure layer on the p-type cladding layer side is made of InGaAsP. InGaAlAs is inserted as a semiconductor thin film having a valence band discontinuity with respect to the structure layer which is almost zero, which does not act as a barrier to holes, and a conduction band discontinuity having a positive value which acts as a barrier to electrons from the light emitting layer. The cladding layer is made of InGaAlAs so that the valence band discontinuity between the structural layer on the p-type cladding layer side and the cladding layer does not become a barrier to holes and is almost zero. Semiconductor light emitting device. 5. An InGaAsP or InGaAlAs light emitting layer or InGaAlAs / InGaAlAs, InGaAsP / InGa sandwiched between separate confinement heterostructure layers of a single composition, a stepped composition, a pseudo graded composition or a graded composition.
In a light emitting layer having a single or multiple quantum well structure composed of AsP or InGaAlAs / InGaAsP and a semiconductor light emitting device having a cladding layer on both sides thereof, the above-mentioned structural layer on the n-type cladding layer side is composed of InGaAlAs. InGaAsP was inserted as a semiconductor thin film having a positive value in which the conduction band discontinuity with respect to the structural layer did not become a barrier to electrons and was almost zero, and the valence band discontinuity became a barrier against holes from the light emitting layer. And the cladding layer is made of InGaAsP such that the conduction band discontinuity between the structural layer and the cladding layer on the n-type cladding layer side is almost zero, which does not act as a barrier to electrons. Semiconductor light emitting device. 6. An InGaAsP or InGaAlAs light-emitting layer or InGaAlAs / InGaAlAs, InGaAsP / InGa sandwiched between separate confinement heterostructure layers of a single composition, a stepped composition, a quasi-gradient composition or a gradient composition.
In a light emitting layer having a single or multiple quantum well structure composed of AsP or InGaAlAs / InGaAsP and a semiconductor light emitting device having a cladding layer on both sides thereof, the above-mentioned structural layer on the p-type cladding layer side is composed of InGaAsP. InGaAlAs is inserted as a semiconductor thin film having a valence band discontinuity with respect to the structure layer which is almost zero, which does not act as a barrier to holes, and a conduction band discontinuity having a positive value which acts as a barrier to electrons from the light emitting layer. The structure layer on the n-type cladding layer side is made of InGaAlAs, and the conduction band discontinuity for the structure layer in the structure layer does not become a barrier to electrons, is almost zero, and the valence band discontinuity is InGaAsP is inserted as a semiconductor thin film having a positive value serving as a barrier to holes from the light emitting layer, and the above-mentioned structural layer and the above cladding layer on the p-type cladding layer side are further inserted. The cladding layer is made of InGaAsP so that the valence band discontinuity between layers does not become a barrier to holes and is almost zero, and the conduction band between the above-mentioned structural layer and the above-mentioned cladding layer on the n-type cladding layer side. A semiconductor light emitting device wherein the cladding layer is made of InGaAlAs so that the discontinuity is almost zero, which does not become a barrier to electrons.