JP2000068585A - Semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser having a multiple quantum well structure (MQN). SOLUTION: A semiconductor laser has a SCH-distortion MQW layer structure consisting a laminated layer of an n-InGaAsP SCH layer 2, a pulled distortion InGaAsP SCH layer 3, a distortion MQW layer 4, a pulled distortion InGaAsP SCH layer 7 and InGaAsP SCH layer 8 on an n-InP substrate 1, and a p-InGaP spacer layer 9 is inserted between an layer structure of SCH- distortion MQW and a p-InP clad layer 10 which becomes as an uppermost layer. The inserted p-InGaP spacer layer 9 prevents electronic carriers injected from the n-InP substrate 1 side to the SCH-distortion MQW from overflowing to the p-InP clad layer 10. As a result, satisfactory high-temperature property and high-output property are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser having a multiple quantum well structure (MQW).

[0002]

2. Description of the Related Art In semiconductor lasers for long wavelength band optical fiber communication, realizing temperature characteristics and high output characteristics is one of the important factors.

In a 1.3 μm band or 1.55 μm band semiconductor laser used for optical fiber communication, an InGaAsP-based material on an InP substrate is generally used as an MQW material. However, this material system
There is a problem that the band discontinuity of the conduction band is small and electrons easily overflow in the multiple quantum well.

Such a problem causes deterioration of high-temperature characteristics and high-output characteristics when processed into a semiconductor laser. In fact, this material system, compared to other material systems,
The characteristic temperature T ₀ is generally poor. In order to avoid such a defect, there is a method of using InAl (Ga) As together with the clad. However, since Al is weak against oxidation, BH (Buri) is used.
However, there is a problem that it is difficult to form an ed (Heterostructure) structure.

Incidentally, in order to improve the high temperature characteristics, FIG.
As shown in FIG. 8, a method of employing compressive strain InAsP as a well layer and introducing tensile strain into a barrier is employed. FIG. 7 is a cross-sectional view of an active layer and a clad layer portion of a conventional semiconductor laser, and FIG. 8 is a band diagram for the layer structure of FIG.

7 and 8, on an n-InP substrate 1, an n-InGaAsP SCH layer 2, a tensile strain In
GaAsP SCH layer 3, strained MQW layer 4, compression strain InA
sP well layer 5, tensile strained InGaAsP barrier layer 6, tensile strained InGaAsP SCH layer 7, InGa
An AsP SCH layer 8 and a p-InP cladding layer 10 are stacked.

[0007]

However, according to this method, the discontinuity of the conduction band between the well and the barrier is improved, but the electron energy level of the barrier is increased. In addition, carrier overflow to the p-clad layer becomes more remarkable, and sufficient high-temperature characteristics cannot be obtained.

In order to solve such a problem, several methods using p-InGaP as a clad have been proposed.

For example, in Japanese Patent Application Laid-Open No. Hei 9-167877 (Prior Art 1), while a GRIN-SCH-MQW emitting at a wavelength of 1.3 μm is grown on an n-InP substrate, a p-GaAs substrate is grown. , Etching stopper layer, p-
A GaAs contact layer and a p-InGaP cladding layer are grown. Then, a method is disclosed in which these epitaxial growth surfaces are fused to each other, and thereafter, the p-GaAs substrate is etched off.

The method of the prior art example 1 has succeeded in incorporating InGaP having a different lattice constant from that of an InP substrate by a method called substrate fusion. However, with the current technology, it is possible to completely eliminate the generation of defects at the substrate fusion interface. In addition, it cannot be applied to large-area wafers, and thus cannot be established as a mass production technology.

Further, for example, Japanese Patent Application Laid-Open No. 8-46286
(Prior example 2) is to grow an n-In _x Ga _{1 -x} As graded buffer layer in which _x varies from 0 to 0.3 on an n-GaAs substrate, and set the lattice constant to In _0.8 Ga _0.2 P. A method is disclosed that is changed to suit. In the technique of the prior art example 2, the growth is lattice-matched during the epitaxial growth of InGaP.

However, the method of the prior art 2 has a problem that it is difficult to sufficiently remove dislocations on the graded buffer layer, and it is difficult to manufacture a highly reliable semiconductor laser.

Japanese Patent Application Laid-Open No. Hei 8-222799 (Prior Art 3) discloses an example in which an n-InGaP substrate is used and the cladding layer is made of InGaP.
According to the method of the preceding example 3, the buried layer must also be made of InGaP. However, in InGaP that is not flatly grown, the composition changes depending on the growth plane orientation, so that lattice irregularity occurs.
The introduction of defects is inevitable. Moreover, it is difficult to manufacture the ternary substrate in the first place.

In a ternary mixed crystal, the composition changes during crystal growth, so that it is difficult to obtain a ternary substrate having a desired composition. Further, since the lattice constant changes, it is necessary to produce a low dislocation substrate. Have difficulty.

Therefore, at present, a reasonable cost of 2 ″ φ3
There is no original substrate, and even if this manufacturing method is adopted, the cost must be extremely high.

An object of the present invention is to provide a semiconductor laser having a layer structure in which electrons do not easily overflow from the MQW to the cladding layer without using Al which is easily oxidized and without introducing crystal defects.

Another object of the present invention is to provide a highly reliable semiconductor laser that can withstand specifications in backbone optical fiber communication.

[0018]

To achieve the above object, a semiconductor laser according to the present invention is a semiconductor laser having a multiple quantum well structure on an InP substrate or a GaAs substrate, wherein the active layer has a multiple quantum well structure. And p-I
At least one tensile strained InGaP layer is provided between the nP clad layer and the nP clad layer.

The thickness of the tensile strained InGaP layer is as follows:
It is below the critical film thickness.

Further, n-InGaAs is formed on an n-InP substrate.
sP SCH layer, tensile strained InGaAsP SCH
Layer, strained MQW layer, tensile strained InGaAsP SCH
SCH- comprising a stack of InGaAsP SCH layers
A semiconductor laser having a strained MQW layer configuration, wherein SCH
-A p-InGaP spacer layer is provided between the strained MQW layer structure and the uppermost p-InP clad layer.

The p-InGaP spacer layer is made of nI
This is a layer for preventing electron carriers injected into the SCH-strained MQW layer configuration from the nP substrate side from overflowing into the p-InP cladding layer.

The thickness of the p-InGaP spacer layer is not less than 3 nm and not more than 100 nm.

The amount of strain of the p-InGaP spacer layer is any value between -0.2% and -1.5%.

Further, n-InGaAs is formed on an n-InP substrate.
sP SCH layer, tensile strained InGaAsP SCH
Layer, strained MQW layer, tensile strained InGaAsP SCH
Semiconductor laser having a SCH-strained MQW layer configuration comprising a stack of InGaAsP SCH layers.
An InP layer is stacked on the AsP SCH layer, and a p-InGaP / p-InP superlattice cladding layer,
-InP clad layer is laminated and p-InGaP / p-I
The nP superlattice cladding layer forms an electron barrier and is composed of a plurality of p-InGaP layers and a plurality of p-InP layers.

The number of p-InGaP / p-InP superlattice cladding layers is 2 or more and 30 or less.

On an n-GaAs substrate, an n-InGaP clad, an n-InGaAsP SCH layer, and a GaAs SCH
Layer, strained MQW layer, GaAs SCH layer, InGaAsP
SCH layer, tensile strained InGaP layer 1, p-InGa
A semiconductor laser having a P cladding layer and a p-GaAs layer, wherein the tensile strained InGaP layer is In _0.4 Ga _0.6 P
The composition is such that tensile strain is applied to a certain amount of GaAs.

As shown in FIG. 1, a semiconductor laser includes an n-InGaAsP SCH layer 2, a tensile strained InGaAsP SCH layer 3, a strained MQW layer 4, a tensile strained InGaAsP SCH layer 7, and an InGaAsP SC
It has a SCH-strained MQW layer configuration composed of a stack of H layers 8. In the present invention, the p-InGaP spacer layer 9 is inserted between the SCH-strained MQW layer structure and the p-InP clad layer 10 as the uppermost layer.

The inserted p-InGaP spacer layer 9 prevents electron carriers injected from the n-InP substrate 1 into the SCH-strained MQW layer structure from overflowing into the p-InP cladding layer 10. You.

The p-InGaP spacer layer 9 is
Since the thickness is less than the critical thickness, misfit dislocations, etc.
The generation of crystal defects is prevented.

Therefore, when this layer structure is applied to a semiconductor laser, the effect of preventing the phenomenon that the light output characteristics are deteriorated at a high temperature and the phenomenon that the light output characteristics are saturated when a large current is injected can be obtained.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view of a multiple quantum well structure (MQW) semiconductor laser according to Embodiment 1 of the present invention. In the following description, the multiple quantum well structure is abbreviated as MQW (Multi-quantum well).

FIG. 2 is a band diagram for the layer structure of FIG. In the MQW semiconductor laser shown in FIG. 1, an n-InGaAsP SCH layer 2 having a composition of 1.0 μm is formed on an n-InP substrate 1 having a surface orientation of (100).
Is a layer thickness of 45 nm, a tensile strained InGaAsP SCH layer 3 is 15 nm, a strained MQW layer 4, a tensile strained InGaAs.
The PSCH layer 7 is made of InGa having a composition of 15 nm and a composition of 1.0 μm.
An AsP SCH layer 8 is formed to a thickness of 45 nm.

Here, SCH means Separate.
Confinement Heterostructu
It is an abbreviation for "re" and has a function of confining light. This strain MQW4 has a compressive strain I of which each of the five layers has a thickness of 4.5 nm.
It comprises an nAsP well layer 5 and a tensile-strained InGaAsP barrier layer 6 having a thickness of 10 nm.

The composition of the compressively strained InAsP well layer 5 is as follows:
This is equivalent to InGaAsP having a composition of 1.22 μm and subjected to 1.5% strain by changing the Ga / III ratio while keeping the As / V ratio constant. Each of the tensile strained InGaAsP SCH layer 3, the tensile strained InGaAsP barrier layer 6, and the tensile strained InGaAsP SCH layer 7 is 1.1 μm.
From the composition InGaAsP, the As / V ratio is kept constant by Ga / I
This is obtained by applying -0.5% strain by changing the II ratio.

From the n-InGaAsP SCH layer 2 to InG
Up to the aAsP SCH layer 8, the SCH-strain MQW
This strain MQW emits light in the 1.3 μm band. Then, according to the present invention, a p-InGaP spacer layer 9 having a tensile strain of 0.5% is inserted between the SCH-strained MQW layer and the p-InP clad layer 10 to a thickness of 30 nm.

Since this layer has a thickness less than the critical thickness,
By inserting the p-InGaP spacer layer 9, generation of crystal defects such as misfit dislocations is prevented. The conduction band edge of the p-InGaP spacer layer 9 is about 55 meV higher than InP. InG
For the aAsP SCH layer 8, approximately 100 me
About V higher.

The energy of 100 meV is sufficiently large with respect to kT at room temperature, and the layer thickness of 30 nm is such that electrons cannot tunnel.
The P spacer layer 9 can sufficiently suppress the overflow of electron carriers from the SCH-strained MQW layer to the p-InP cladding layer 10.

Here, the p-InP cladding layer 10
If hole carrier injection into the CH-strained MQW layer is hindered, a problem occurs in the semiconductor laser characteristics.
In the P spacer layer 9, the heavy hole level and the light hole level are split by the strain stress.
Since the energy level has no obstacle to carrier injection, there is no problem in hole carrier injection.

Therefore, in such a configuration, p-In
Since the GaP spacer layer 9 is a barrier capable of suppressing the carrier overflow of electrons without impeding the injection of hole carriers at all, the SCH-strained MQW layer can be sufficiently used even at a high temperature or at a high current injection. In addition, electron carriers can be confined.

Therefore, in the operation of the semiconductor laser,
The effect that temperature characteristics and high output characteristics are greatly improved is brought about. This makes it possible to realize an APC-free laser in which the change in optical output is kept within 2 dB from -40 ° C to 85 ° C.

This will be further described with reference to FIG.
In FIG. 2, an upper band diagram shows an electron band diagram, and a lower diagram shows a hole band diagram. InG used for long wavelength semiconductor laser for long distance optical fiber communication
The aAsP material system is characterized in that the conduction band discontinuity is smaller than the valence band discontinuity.

If the electron has a smaller effective mass than the hole,
This causes a problem that carrier overflow of electrons easily occurs. In the present invention, the reason why tensile strain is introduced into the barrier layer is to increase the electron barrier and confine carriers in the well. Thus, the distortion MQ
When the optimum design is performed on the W layer 4, there arises a problem that the electron energy level of InP does not become sufficiently high with respect to the tensile strained InGaAsP barrier layer 6.

In this example, p-InP
The energy height of the cladding layer 10 becomes about 50 meV, and carrier overflow from the barrier and SCH to the p-InP cladding layer 10 becomes a serious problem. In particular, when the temperature is high or when a large current is injected, the phenomenon becomes larger.

According to the present invention, it can be seen that the presence of the p-InGaP spacer layer 9 significantly improves the suppression of carrier overflow in that the barrier height of the electron with respect to the barrier and SCH is doubled.

This provides another degree of freedom for semiconductor laser design. Change the composition of the p-cladding layer to In
When it is designed to be fixed to P, p-doping is performed at a high concentration in order to raise the electron level of the p-cladding layer as much as possible.

However, with InP doped with Zn at a high concentration, there is a problem that the loss of guided light is large and the threshold current and efficiency of the semiconductor laser characteristics are deteriorated. In mentioned above
Since the effect of inserting GaP increases the energy level of electrons much more effectively than increasing the p concentration, this design has the advantage that the p concentration does not need to be increased as loss becomes a significant problem. .

As a result, the semiconductor laser of the present invention has improved performance in any of the threshold current, the efficiency, the temperature characteristic, the high output characteristic, and the analog characteristic as compared with the conventional one. Moreover, in the present embodiment, since the tensile strained InGaP layer is epitaxially grown within the critical film thickness and a defect is not introduced at the time of forming the layer structure, the manufacturing method is
Although having an nGaP cladding, much higher reliability can be obtained as compared with the prior art 1 by substrate fusion and the prior art 2 of the graded buffer layer, in which the introduction of crystal defects is unavoidable.

In the semiconductor laser shown in this embodiment, 85
, MTF (Median Time) at 15mW operation
to Failure) can be stably obtained for 100,000 hours or more. In addition, since no special manufacturing method is required for introducing the p-InGaP spacer layer 9, 3
As compared with the method of the prior art example 3 using the original substrate, an effect is obtained that the production can be performed at an extremely low cost.

The layer structure of the semiconductor laser according to the present embodiment shown in FIG. 1 is manufactured by metal organic chemical vapor deposition.
Metal-organic vapor phase epitaxy often uses MO-VPE (Metal
-Organic Vapor Phase Edit
axy). In MO-VPE, organometallic, trimethylindium (TMI),
Trimethylgallium (TMG) is used, and arsine (AsH ₃ ) and phosphine (PH ₃ ) are used as group V raw materials.

As the dopant, disilane (Si
₂ H ₆ ) and trimethylzinc (TMZn) are used. n-I
The nP substrate 1 is heated to 650 ° C. in a reaction furnace, and each source gas is switched for each layer to grow into the structure shown in FIG. In particular, in the present embodiment, InGaAsP SC
For the H layer 8 and the p-InGaP spacer layer 9, Ga
Since the / III ratio is equal to 0.07, switching this interface only requires turning off the supply of AsH ₃ .

The p-InGaP spacer layer 9 and p-I
Switching with the nP cladding layer 10 only requires stopping the supply of TMG. Thus, in the present embodiment, p-In
Since the interface switching before and after the GaP spacer layer 9 employs the step of using one source gas,
Before and after lamination of the p-InGaP spacer layer 9, there is no metamorphic layer at all, and the concern of crystal quality degradation due to InGaP insertion is minimized.

In the above embodiment, the strain amount of the p-InGaP spacer layer 9 may be any value between -0.2% and -1.5%. 0.2% tensile strain
Otherwise, it does not stop the overflow of electron carriers. Further, when a tensile strain of 1.5% or more is applied, misfit dislocations occur, and a highly reliable semiconductor laser cannot be obtained.

The layer thickness of the p-InGaP spacer layer 9 must be 3 nm or more and 100 nm or less.
If it is 3 nm or less, electrons pass through due to a tunnel phenomenon, and if it is 100 nm or more, crystal defects occur, and good reliability cannot be obtained.

Further, the InGaAsP SCH layer 8 and p-I
An InP spacer layer having a thickness of 5 nm to 50 nm may be inserted between the nGaP spacer layers 9. InP is In
Since it is perfectly lattice-matched to the P substrate, the insertion of this has the effect of improving the crystallinity.

Further, in the above embodiment, an example in which InAsP is used for the well layer has been described.
P or InGaAs may be used. In addition, the Fabry-Perot laser in the 1.3 μm band was described.
It goes without saying that the present invention can be applied to a 1.55 μm semiconductor laser and a distributed feedback laser.

(Embodiment 2) In Embodiment 1, p
Although the -InGaP layer is a single layer, by using a plurality of layers, the carrier overflow of electrons can be further reduced. The configuration is shown in FIG. FIG.
FIG. 4 is a band diagram of FIG. 3. In this figure, n
From the -InP substrate 1 to the InGaAsP SCH layer 8
This is the same as the first embodiment.

In the second embodiment, InGaAsP
On the SCH layer 8, an InP layer 11 is laminated with a thickness of 20 nm, and a p-InGaP / p-InP superlattice cladding layer 12 and a p-InP cladding layer 10 are laminated thereon in that order. p-InGaP / p-InP superlattice cladding layer 1
No. 2 is composed of 10 layers of 4 nm p-InGaP layers and 9 layers of 2 nm p-InP.
It has a layer thickness of nm.

The p-InGaP layer has a strain of -0.5% and the electron level is about 55 meV higher than that of InP. Also, p
The quantum level of electrons formed in p-InP sandwiched between -InGaP is at a position of about 50 meV with respect to InP.

Accordingly, the electron barrier height of the p-InGaP / p-InP superlattice cladding layer functions almost as well as p-InGaP. On top of that, a total layer thickness of 58n
The effect as an electron barrier increases as the thickness increases to m. The increase in the total layer thickness is not merely due to the addition of InP, but also increases the total thickness of each layer of InGaP.

This is because the total critical film thickness is increased by inserting InP lattice-matching. Further, since the InP layer 11 that is perfectly lattice-matched is inserted once, crystal defects are less likely to occur in the layer above it.

On the other hand, on the valence band side, InP acts as a barrier for the light hole. However, since InP is as thin as 2 nm, it can travel in a tunnel. In addition, since there is a sufficient hole carrier concentration due to p doping,
The p-InGaP / p-InP superlattice cladding layer 12 does not hinder the movement of hole carriers.

Therefore, in the structure of the p-InGaP / p-InP superlattice cladding layer 12, an effect that the cladding layer is effectively widened and the high temperature characteristics and the high output characteristics are further improved is obtained.

Further, since there are many interfaces of p-InGaP / p-InP, Zn from p-InP clad layer 10
Is trapped at these interfaces and the SCH-strain M
Diffuse diffusion to the QW layer becomes difficult. Zn to SCH-strain MQW
Is small, the loss of guided light is small. Therefore, the effect of reducing the threshold current of the semiconductor laser and improving the external efficiency can be obtained.

In the structure of the present invention, p-InGaP /
The number of p-InP superlattice cladding layers 12 is 2 or more and 30
Any of the following may be used. If the number of layers is 30 or more, crystal defects occur, and the reliability of the semiconductor laser decreases. Further, the thickness of each p-InGaP layer or the thickness of the p-InP layer is preferably in the range of 1 nm to 30 nm.

When the layer thickness is 1 nm or less, the thickness is not effectively increased with respect to the composition fluctuation at the interface. 30 nm
If there are two or more layers, crystal defects will also occur.

(Embodiment 3) In Embodiments 1 and 2,
The InP substrate is a GaAs substrate, and the p-InGaP layer is G
It can be constituted by tensile strain on the aAs substrate. The configuration for that is shown in FIGS. 5 and 6 as a third embodiment.

In the semiconductor laser of this embodiment, 0.98
It oscillates at a wavelength of μm. For a 0.98 μm laser, A
1GaAs is used for the cladding layer and InGaP
The layer may be used as a cladding. A that is susceptible to oxidation
l, it is difficult to secure the reliability.
In aP, since the cladding is not sufficiently high, AlGaAs
However, there is a problem that a high output cannot be obtained as compared with. Embodiment 3 is a structure for solving this.

5 and 6, the n-GaAs substrate 10
1, n-InGaP cladding 102, n-InGaAs
sP SCH layer 2, GaAs SCH layer 103, strained MQW
Layer 4, GaAs SCH layer 107, InGaAsP SC
H layer 8, tensile strained InGaP layer 109, p-InGa
A P cladding layer 110 and a p-GaAs layer 111 are formed.

The strained MQW layer 4 has two layers of compressive strain InG.
It comprises an aAs well layer 105 and a GaAs barrier layer 106. n-InGaP cladding 102, p-InG
The composition of the aP cladding layer 110 is In _0.48 Ga _0.52 P
In this case, the composition is lattice-matched to GaAs, but the tensile strained InGaP layer 109 has a G of about In _0.4 Ga _0.6 P.
The composition is such that tensile strain is applied to aAs. Then, the electron level of the tensile strained InGaP layer 109 is changed to p-
It can be higher than the InGaP cladding layer 110.

Therefore, the p-InGaP
Carrier overflow of electrons to the cladding layer 110 is suppressed, high output characteristics are improved, and the object of the present invention is achieved. Of course, crystal defects do not occur, and high reliability is obtained.

[0072]

According to the present invention, since at least one tensile strained InGaP layer is inserted between the SCH-strained MQW layer and the p-InP clad layer formed on the substrate, the SCH-strained MQW is injected into the SCH-strained MQW. It serves to prevent incoming electron carriers from overflowing into the p-InP cladding layer.

Accordingly, when the layer structure according to the present invention is applied to a semiconductor laser, there is an effect that a phenomenon that the light output characteristics are deteriorated at a high temperature and a phenomenon that the light output characteristics are saturated when a large current is injected can be prevented. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a semiconductor laser according to the present invention.

FIG. 2 is a band diagram showing a first embodiment of the semiconductor laser of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the semiconductor laser according to the present invention.

FIG. 4 is a band diagram showing a second embodiment of the semiconductor laser according to the present invention.

FIG. 5 is a sectional view showing a third embodiment of the semiconductor laser according to the present invention.

FIG. 6 is a band diagram showing a third embodiment of the semiconductor laser according to the present invention.

FIG. 7 is a sectional view showing a conventional semiconductor laser.

FIG. 8 is a band diagram showing a conventional semiconductor laser.

[Explanation of symbols]

 Reference Signs List 1 n-InP substrate 2 n-InGaAsP SCH layer 3 tensile strained InGaAsP SCH layer 4 strained MQW layer 5 compressive strained InAsP well layer 6 tensile strained InGaAsP barrier layer 7 tensile strained InGaAsP SCH layer 8 InGaAsP SCH layer 9 InGaAsP SCH layer p-InP cladding layer 11 InP layer 12 p-InGaP / p-InP superlattice cladding layer 101 n-GaAs substrate 102 n-InGaP cladding layer 103 GaAs SCH layer 105 compression-strained InGaAs well layer 106 GaAs barrier layer 107 GaAs SCH layer 109 Tensile strain InGaP layer 110 p-InGaP cladding layer 111 p-GaAs layer

Claims (9)

[Claims] 1. A semiconductor laser having a multiple quantum well structure on an InP substrate or a GaAs substrate, wherein at least one tensile strained InGaP layer is provided between an active layer having a multiple quantum well structure and a p-InP cladding layer. A semiconductor laser comprising: 2. The semiconductor laser according to claim 1, wherein the thickness of the tensile-strained InGaP layer is equal to or less than a critical thickness. 3. An n-InGaAsP substrate on an n-InP substrate.
SCH layer, tensile strained InGaAsP SCH layer, strained MQW layer, tensile strained InGaAsP SCH layer, In
SCH-strain MQW composed of a stack of GaAsP SCH layers
A semiconductor laser having a layer structure, comprising a p-InGaP spacer layer between a SCH-strained MQW layer structure and a p-InP clad layer as an uppermost layer. 4. The p-InGaP spacer layer comprises n-InP
4. The semiconductor laser according to claim 3, wherein the semiconductor laser is a layer for preventing electron carriers injected into the SCH-strained MQW layer configuration from the substrate side from overflowing into the p-InP cladding layer. 5. The layer thickness of the p-InGaP spacer layer is 3
4. The semiconductor laser according to claim 3, wherein the thickness is not less than 100 nm and not more than 100 nm. 6. The strain amount of the p-InGaP spacer layer is −
4. The semiconductor laser according to claim 3, wherein the value is any value between 0.2% and -1.5%. 7. An n-InGaAsP on an n-InP substrate.
SCH layer, tensile strained InGaAsP SCH layer, strained MQW layer, tensile strained InGaAsP SCH layer, In
SCH-strain MQW composed of a stack of GaAsP SCH layers
A semiconductor laser having a layer configuration, wherein an InP layer is laminated on an InGaAsP SCH layer, and a p-InGaP / p-InP superlattice cladding layer and a p-InP cladding layer are sequentially laminated thereon, A semiconductor laser, wherein the InGaP / p-InP superlattice cladding layer forms an electron barrier and comprises a plurality of p-InGaP layers and a plurality of p-InP layers. 8. The semiconductor laser according to claim 7, wherein the number of p-InGaP / p-InP superlattice cladding layers is 2 or more and 30 or less. 9. An n-InGaP cladding, an n-InGaAsP SCH layer, and a GaAs S layer on an n-GaAs substrate.
CH layer, strained MQW layer, GaAs SCH layer, InGaAs
sP SCH layer, tensile strained InGaP layer, p-InG
A semiconductor laser having an aP cladding layer and a p-GaAs layer, wherein the tensile strained InGaP layer has a G of about In _0.4 Ga _0.6 P.
A semiconductor laser having a composition in which tensile strain is applied to aAs.