JPH09162500A - Semiconductor light emitting device - Google Patents

Abstract

(57) An object of the present invention is to provide a semiconductor light emitting device using a II-VI group compound semiconductor which has few point defects due to lattice strain between an active layer and a substrate and has a long life and high reliability. An n-type ZnSe is formed on an n-type GaAs substrate.
The n-type ZnMgSSe cladding layer 3, the n-type ZnSSe optical waveguide layer 4, and the Zn _1-x Cd _x O _y S via the buffer layer 2.
_1-y active layer 5, p-type ZnSSe optical waveguide layer 6, p-type ZnM
gSSe clad layer 7, p-type ZnSe contact layer 8,
p-type ZnSe / ZnTe multiple quantum well layer 9 and p-type Z
A laser structure is formed by sequentially stacking the nTe contact layers 10. Of these layers, at least Zn _1-x Cd
_x O _y S _1-y active layer 5 has a lattice constant of n-type GaAs substrate 1
Is almost equal to the lattice constant of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and is particularly suitable for application to a semiconductor light emitting device using a II-VI compound semiconductor, such as a semiconductor laser or a light emitting diode.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a semiconductor laser capable of emitting blue or green light in order to increase the recording / reproducing density or the resolution of an optical disk or a magneto-optical disk for recording / reproducing using a laser beam. It is rising. And, as this kind of semiconductor laser, ZnCd which is a II-VI group compound semiconductor having a large band gap is used.
A semiconductor laser using Se as a material for an active layer (light emitting layer) has been receiving attention.

FIG. 3 shows a conventional semiconductor laser using such a ZnCdSe active layer. This semiconductor laser is a so-called SCH (Separate Confinement Heterostr
ucture) structure.

As shown in FIG. 3, in this conventional semiconductor laser, for example, n-type GaA having a (100) plane orientation is used.
On the s substrate 101, an n-type ZnSe buffer layer 102 doped with Cl as an n-type impurity, an n-type ZnMgSSe cladding layer 103 similarly doped with Cl as an n-type impurity, and similarly doped with Cl as an n-type impurity. N
Type ZnSSe optical waveguide layer 104, ZnCdS which is a light emitting layer
e active layer 105, p-type ZnSSe optical waveguide layer 106 doped with, for example, N as a p-type impurity, p-type ZnMgSSe cladding layer 107 similarly doped with N as a p-type impurity, and similarly doped with N as a p-type impurity. P-type ZnSe contact layer 108, a barrier layer made of p-type ZnSe similarly doped with N as a p-type impurity, and a well layer made of p-type ZnTe are alternately stacked.
Type ZnSe / ZnTe multiple quantum well (MQW) layer 109
And p-type Z which is similarly doped with N as a p-type impurity
The nTe contact layer 110 is sequentially stacked.

Here, the p-type ZnSe / ZnTe MQW layer 109 and the p-type ZnTe contact layer 110 have a stripe shape extending in one direction.

P-type Zn on both sides of the stripe portion
A polyimide film or Al ₂ is formed on the Se contact layer 108.
An insulating layer 111 made of an O ₃ film is formed. Then, the stripe-shaped p-type ZnTe contact layer 110 is formed.
A p-side electrode 112 is formed on the insulating layer 111. The p-side electrode 112 is the p-type ZnTe contact layer 1
It is in ohmic contact with 10, and this portion serves as a current path. Here, as the p-side electrode 112,
For example, a Pd / Pt / Au electrode having a structure in which a Pd film, a Pt film, and an Au film are sequentially stacked is used. On the other hand, n-type Ga
On the back surface of the As substrate 101, an n-type electrode such as an In electrode is formed.
The side electrode 113 is in ohmic contact.

In order to manufacture the conventional semiconductor laser configured as described above, first, molecular beam epitaxy (MB
E) method is used to form n-type Zn on the n-type GaAs substrate 101.
Se buffer layer 102, n-type ZnMgSSe cladding layer 103, n-type ZnSSe optical waveguide layer 104, ZnCdSe
Active layer 105, p-type ZnSSe optical waveguide layer 106, p-type Z
The nMgSSe cladding layer 107, the p-type ZnSe contact layer 108, the p-type ZnSe / ZnTe MQW layer 109, and the p-type ZnTe contact layer 110 are sequentially grown. Here, the n-type ZnSe buffer layer 102, the n-type Zn
The doping of Cl as an n-type impurity in the MgSSe cladding layer 103 and the n-type ZnSSe optical waveguide layer 104 is
For example, ZnCl ₂ is used as a dopant. In addition, the p-type ZnSSe optical waveguide layer 106, the p-type ZnMgSS
e clad layer 107, p-type ZnSe contact layer 10
8. N-doping as a p-type impurity of the p-type ZnSe / ZnTe MQW layer 109 and the p-type ZnTe contact layer 110 generates N ₂ plasma using a radio frequency (RF) or electron cyclotron (ECR) plasma cell, By using N radicals generated by

Next, a stripe-shaped resist pattern (not shown) having a predetermined width extending in one direction is formed on the p-type ZnTe contact layer 110, and the p-type ZnTe contact layer 110 and the p-type ZnTe contact layer 110 are formed using this resist pattern as a mask. The p-type ZnSe / ZnTe MQW layer 109 is etched by the wet etching method. This gives p
-Type ZnSe / ZnTe MQW layer 109 and p-type ZnT
The e-contact layer 110 is patterned into a stripe shape.

Next, a polyimide film or Al ₂ O _{3 is formed on the} entire surface while leaving the resist pattern used for the above etching.
After forming the film, this resist pattern is removed together with the polyimide film and the Al ₂ O ₃ film formed thereon (lift-off). As a result, the insulating layer 111 made of a polyimide film or an Al ₂ O ₃ film is formed only on the p-type ZnSe contact layer 108 on both sides of the stripe portion.

Next, a Pd film and a P film are formed on the entire surfaces of the stripe-shaped p-type ZnTe contact layer 110 and the insulating layer 111.
The t film and the Au film are sequentially formed by the vacuum deposition method to form Pd.
/ Pt / Au electrode is formed on the p-side electrode 112, and then heat treatment is performed if necessary, and the p-side electrode 112 is formed.
Is brought into ohmic contact with the p-type ZnTe contact layer 110. On the other hand, an n-side electrode 113 such as an In electrode is formed on the back surface of the n-type GaAs substrate 101 to make ohmic contact.

Next, the n-type GaAs substrate 101 having the laser structure formed as described above is cleaved in a bar shape to form both resonator end faces, and then end face coating is performed by a vacuum deposition method or the like. After this, the bar is cleaved to form a chip, and the laser chip thus obtained is packaged.

[0012]

However, in the above-described conventional semiconductor laser, since the lattice constant of the ZnCdSe active layer 105 is larger than that of the n-type GaAs substrate 101, a large lattice is formed only in the ZnCdSe active layer 105. Distortion is inherent, resulting in the following problems.

That is, ZnCdS as a quantum well layer
The emissive characteristics of the ZnCdSe active layer formed on the GaAs substrate by sandwiching the ZnSSe layer as a barrier layer on both sides of the e active layer indicate that ZnCdSe is
The following is known about the emission characteristics of the active layer and the strain effect of the ZnSSe layer. That is, ZnC
The emission characteristics of the dSe layer are sensitively affected by the strain between the GaAs substrate and the ZnSSe layer, and when the strain increases, the emission intensity sharply decreases. It is considered that this is because the lattice distortion reduces the generation energy of point defects generated at the hetero interface.

Further, it is generally known that the dislocation generated in the active layer after crystal growth is absorbed by the electron-hole recombination energy accompanying light emission and propagates, and the dislocation density increases as the strain increases. ing.

From the above, in the semiconductor laser using the ZnCdSe active layer, it is desired that the ZnCdSe active layer is lattice-matched with the substrate. This also applies to a semiconductor laser using a ZnSe active layer. Furthermore, this is the same also in a light emitting diode using a ZnCdSe active layer or a ZnSe active layer.

Therefore, the present invention provides a semiconductor light emitting device using a II-VI group compound semiconductor having a long life and high reliability by suppressing point defects due to lattice distortion between the active layer and the substrate. To do.

[0017]

Means for Solving the Problems The present inventor has made intensive studies to achieve the above object. The outline is as follows.

FIG. 2 shows the relationship between the lattice constant and the band gap energy (E _g ) of a typical binary II-VI compound semiconductor. Here, the data for binary II-VI compound semiconductors other than ZnO are measured at liquid nitrogen temperature (77K), and the data for ZnO are measured at liquid helium temperature (4.2K). is there. In FIG. 2, the broken line, the one-dot chain line, the solid line, and the two-dot chain line parallel to the horizontal axis represent the lattice constant of GaAs (0.5653 nm) and the lattice constant of InP (0.5, respectively).
86 nm), the lattice constant of GaP (0.545 nm) and the lattice constant of ZnSe (0.567 nm).

It can be seen from FIG. 2 that the lattice constant of GaAs is within the range of the lattice constant that can be obtained by appropriately combining CdSe, CdS, ZnSe and ZnO to form a mixed crystal. Generally, ZnO crystals are known to have a wurtzite-type crystal structure or a rock-salt-type crystal structure, but the literature (SMSze, "Semiconduc
tor Devices Physics and Technology ", John Wiley &
Sons, Inc., 1985, p.513) has a lattice constant of 0.
The band gap energy is 458 nm and 3.3 eV. In addition, in general, when another crystal is added to the base material having a zinc blende type crystal structure, the crystal to be added is a wurtzite type crystal structure or rock salt type crystal structure Is also known to have a zinc blende type crystal structure (for example, when MgS having a rock salt type crystal structure is added to ZnSe having a zinc blende type crystal structure, the resulting ZnMgSSe crystal has a zinc blende structure). It has a type crystal structure). Therefore, it is considered that the relationship between the band gap energy and the lattice constant obtained from FIG. 2 hardly changes.

Here, for example, the line showing the lattice constant of GaAs is CdSe-ZnO, CdS-ZnO or ZnS.
By obtaining a point that intersects the line of the combination of e-ZnO and drawing a perpendicular line from the intersection to the horizontal axis, the band gap that can be realized by the combination can be obtained. They are 2.2 respectively from FIG.
2eV, 2.56eV, 2.80eV, and the emission wavelengths near them are 585 nm and 5 respectively.
It becomes about 04 nm and 459 nm. This is because if the active layer is formed by these mixed crystals, the active layer and the GaAs substrate are lattice-matched and the temperature is from 459 nm to 585 near room temperature.
It shows that emission wavelengths up to nm can be obtained.

Similarly, the line showing the lattice constant of InP is Cd.
A band gap that can be realized by these combinations can be obtained by finding a point that intersects the line of the combination of Se-ZnO or CdSe-CdS and drawing a perpendicular line from the intersection to the horizontal axis. They are,
From FIG. 2, it becomes 1.98 eV and 2.33 eV, respectively, and the emission wavelengths at around room temperature for them are 6 respectively.
It becomes about 60 nm and 556 nm. This is because if the active layer is formed by a mixed crystal of these, the active layer and the InP substrate are lattice-matched, and 556 nm to 660 n near room temperature.
It shows that emission wavelengths up to m can be obtained.

Next, the line showing the lattice constant of GaP is CdS.
The band gap that can be realized by the combination can be obtained by finding a point that intersects the line of the combination of e-ZnO or ZnSe-ZnS and drawing a perpendicular line from the intersection to the horizontal axis. From Fig. 2, they are 2.41 eV and 3.65 eV, respectively.
The emission wavelengths around them are 537 each.
nm and 349 nm. This indicates that if the active layer is formed of these mixed crystals, it is possible to obtain an emission wavelength from 349 nm to 537 nm near room temperature while lattice matching the active layer and the GaP substrate.

Next, the line showing the lattice constant of ZnSe is Cd.
A line intersecting with the line of the combination of Se-ZnO or CdS-ZnO and the point of ZnSe is obtained, and a perpendicular line is drawn from the intersection with respect to the horizontal axis to obtain the band gap that can be realized by the combination. it can. They are 2.18 eV from FIG. 2, respectively.
2.54 eV and 2.79 eV, respectively, and the emission wavelengths around them are 596 nm and 508 n, respectively, near room temperature.
m, about 461 nm. This indicates that if the active layer is formed of these mixed crystals, the emission wavelength from 461 nm to 596 nm can be obtained near room temperature while lattice-matching the active layer and the ZnSe substrate.

The present invention was devised based on the above examination.

That is, in order to achieve the above object, the present invention provides at least one group II element selected from the group consisting of Zn, Mg, Cd, Hg and Be, and S.
In a semiconductor light emitting device using a II-VI group compound semiconductor consisting of at least one or more VI group elements selected from the group consisting of e, S, Te and O, at least the lattice constant of the active layer is the lattice constant of the substrate. It is characterized by almost matching with.

In the present invention, the active layer is at least O.
II-VI compound semiconductor containing

In one embodiment of the present invention, the active layer comprises at least Zn, Cd, O and Se. In this case, the emission wavelength is, for example, 380 nm to 6 around room temperature.
It can be 20 nm.

In another embodiment of the present invention, the active layer is made of Zn, Cd, O and S. In this case, the emission wavelength is, for example, 380 nm to 540 nm near room temperature.
It can be.

In yet another embodiment of the present invention, the active layer is made of Zn, O and Se.

In the present invention, the substrate is, for example, GaA.
s, InP, GaP, ZnSe and the like.

According to the present invention constructed as described above, at least the lattice constant of the active layer is substantially equal to the lattice constant of the substrate, so that the point caused by the lattice strain between the active layer and the substrate. Generation of defects can be suppressed.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a semiconductor laser according to an embodiment of the present invention. This semiconductor laser is
It has a SCH structure.

As shown in FIG. 1, in the semiconductor laser according to this embodiment, for example, S as an n-type impurity
An n-type GaAs substrate 1 having a (100) plane orientation doped with i is doped with, for example, Cl as an n-type impurity.
Type ZnSe buffer layer 2, similarly as an n-type impurity Cl
N-type ZnMgSSe cladding layer 3 doped with, n-type ZnSSe similarly doped with Cl as an n-type impurity
The optical waveguide layer 4, the Zn _1-x Cd _x O _y S _1-y active layer 5 which is a light emitting layer, the p-type ZnSSe optical waveguide layer 6 in which N is doped as a p-type impurity, and the N-type is similarly used as a p-type impurity. Zn-doped p-type ZnMgSSe cladding layer 7, p-type ZnSe contact layer 8 similarly doped with N as a p-type impurity, p-type ZnSe barrier layer similarly doped with N as a p-type impurity, and p P-type ZnSe / ZnTe in which well layers made of p-type ZnTe are alternately stacked
An MQW layer 9 and a p-type ZnTe contact layer 10 similarly doped with N as a p-type impurity are sequentially stacked.

Here, the p-type ZnSe / ZnTe MQW layer 9 and the p-type ZnTe contact layer 10 have stripe shapes extending in one direction.

P-type Zn on both sides of the stripe portion
A polyimide film or Al ₂ O ₃ is formed on the Se contact layer 8.
An insulating layer 11 made of a film is formed. Then, the p-side electrode 12 is formed on the stripe-shaped p-type ZnTe contact layer 10 and the insulating layer 11. The p-side electrode 12 makes ohmic contact with the p-type ZnTe contact layer 10, and this portion serves as a current path. Here, as the p-side electrode 12, for example, a Pd film and Pt are used.
A Pd / Pt / Au electrode having a structure in which a film and an Au film are sequentially stacked is used. On the other hand, an n-side electrode 13 such as an In electrode is in ohmic contact with the back surface of the n-type GaAs substrate 1.

In the semiconductor laser according to this embodiment, the Cd composition ratio x and the O composition ratio y of the Zn _1-x Cd _x O _y S _1-y active layer 5 are such that the Zn _1-x Cd _x O _y S
The lattice constant of the _1-y active layer 5 is substantially equal to the lattice constant of the n-type GaAs substrate 1, that is, Zn _1-x Cd _x
O _y S _1-y active layer 5 is selected to substantially lattice matched with the n-type GaAs substrate 1. For example, Zn _1-x Cd _x O
_{When the} Cd composition ratio x and the O composition ratio y in the _y S _{1 -y} active layer 5 are 0.2 and 0.17, respectively, Z
The n _1-x Cd _x O _y S _1-y active layer 5 is formed on the n-type GaAs substrate 1
It is possible to realize an emission wavelength of 504 nm near room temperature while making a lattice match with.

The n-type ZnMgSSe cladding layer 3,
n-type ZnSSe optical waveguide layer 4 and p-type ZnSSe optical waveguide layer 6
The Mg composition ratio and the S composition ratio of the p-type ZnMgSSe cladding layer 7 are such that the lattice constants of these layers substantially match the lattice constants of the n-type GaAs substrate 1, that is, these layers are the same as those of the n-type GaAs substrate. It is chosen to be nearly lattice matched.

Next, a method of manufacturing the semiconductor laser according to this embodiment having the above-described structure will be described.

That is, in order to manufacture the semiconductor laser according to this embodiment, first, the n-type G is formed by the MBE method.
The n-type ZnSe buffer layer 2 and the n-type Z are formed on the aAs substrate 1.
nMgSSe cladding layer 3, n-type ZnSSe optical waveguide layer 4, Zn _1-x Cd _x O _y S _1-y active layer 5, p-type ZnSS
e optical waveguide layer 6, p-type ZnMgSSe cladding layer 7, p-type ZnSe contact layer 8, p-type ZnSe / ZnTeMQ
The W layer 9 and the p-type ZnTe contact layer 10 are sequentially grown.

In the growth of each layer by the MBE method, for example, Zn is used as a Zn raw material, Mg is used as a Mg raw material, ZnS is used as an S raw material, Se is used as a Se raw material, and Cd is used as a Cd raw material. ZnO is used as the O raw material. In addition, the n-type ZnSe buffer layer 2, the n-type ZnMgSSe cladding layer 3, and the n-type ZnS
The doping of Cl as an n-type impurity in the Se optical waveguide layer 4 is performed by using ZnCl ₂ as a dopant, for example. Furthermore, p-type ZnSSe optical waveguide layer 6, p-type ZnMg
SSe cladding layer 7, p-type ZnSe contact layer 8, p
Doping of N as a p-type impurity in the n-type ZnSe / ZnTe MQW layer 9 and the p-type ZnTe contact layer 10 generates N ₂ plasma using an RF or ECR plasma cell, and uses N radicals generated thereby. To do.

Next, a stripe-shaped resist pattern (not shown) having a predetermined width and extending in one direction is formed on the p-type ZnTe contact layer 10, and then the p-type ZnTe contact layer 10 and the resist pattern are used as a mask. The p-type ZnSe / ZnTe MQW layer 9 is etched by the wet etching method. As a result, p-type ZnS
The e / ZnTe MQW layer 9 and the p-type ZnTe contact layer 10 are patterned in a stripe shape.

Next, a polyimide film or Al ₂ O _{3 is formed on the} entire surface while leaving the resist pattern used for the above etching.
After forming the film, this resist pattern is removed together with the polyimide film and the Al ₂ O ₃ film formed thereon (lift-off). As a result, the insulating layer 11 made of a polyimide film or an Al ₂ O ₃ film is formed only on the p-type ZnSe contact layer 8 on both sides of the stripe portion.

Next, a Pd film, a Pt film, and an Au film are sequentially formed on the entire surface of the stripe-shaped p-type ZnTe contact layer 10 and the insulating layer 11 by a vacuum deposition method or the like to form Pd.
The p-side electrode 12 formed of the / Pt / Au electrode is formed, and then heat treatment is performed as necessary to remove the p-side electrode 12 from the p-side electrode 12.
An ohmic contact is made with the ZnTe contact layer 8. On the other hand, an n-side electrode 13 such as an In electrode is formed on the back surface of the n-type GaAs substrate 1 to make ohmic contact.

Next, the n-type GaAs substrate 1 having the laser structure formed as described above is cleaved in a bar shape to form both resonator end faces, and then end face coating is performed by a vacuum deposition method or the like. After this, the bar is cleaved to form a chip, and the laser chip thus obtained is packaged.

As described above, in the semiconductor laser according to this embodiment, the lattice constant of the Zn _1-x Cd _x O _y S _1-y active layer 5 is almost equal to the lattice constant of the n-type GaAs substrate 1. Therefore, it is possible to suppress the generation of point defects due to the lattice strain between the Zn _1-x Cd _x O _y S _1-y active layer 5 and the n-type GaAs substrate 1. As a result, the density of point defects induced by carrier recombination during oscillation of the semiconductor laser can be reduced, and the life of the semiconductor laser can be extended and the reliability can be improved.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention. .

For example, in the above embodiment, Z
ZnO is used as an O raw material when the n _1-x Cd _x O _y S _1-y active layer 5 is grown by the MBE method. For example, an O ₂ plasma is generated using an RF or ECR plasma cell, and This Zn using O generated by
_{The 1-x} Cd _x O _y S _1-y active layer 5 may be grown.

The materials and numerical values in the above-described embodiment are merely examples, and materials and numerical values different from these may be used. For example, instead of the Zn _1-x Cd _x O _y S _1-y active layer 5, another I that is substantially lattice-matched with the n-type GaAs substrate 1 is used.
An I-VI compound semiconductor may be used. Also, n-type Z
An n-type ZnSSe buffer layer may be used instead of the nSe buffer layer 2, or both of them may be used.

Although the n-type GaAs substrate 1 is used as the substrate in the above embodiment, an n-type InP substrate, an n-type GaP substrate, an n-type ZnSe substrate or the like may be used as the substrate. .

Further, although the n-type GaAs substrate 1 is used as the substrate in the above-described embodiment, for example, p-type
A type GaAs substrate may be used and the laser structure may be formed thereon.

In the above-described embodiment, the SC
The case where the present invention is applied to a semiconductor laser having an H structure has been described.
It may be applied to a semiconductor laser having a heterostructure), and further applied to a light emitting diode.

[0053]

As described above, according to the present invention, at least the lattice constant of the active layer substantially matches the lattice constant of the substrate, which causes the lattice strain between the active layer and the substrate. Generation of point defects can be suppressed, and thus a semiconductor light emitting device using a II-VI group compound semiconductor having a long life and high reliability can be realized.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing a relationship between a lattice constant and a band gap energy of a binary II-VI compound semiconductor.

FIG. 3 is a cross-sectional view showing a conventional semiconductor laser using a ZnCdSe active layer.

[Explanation of symbols]

1 n-type GaAs substrate 2 n-type ZnSe buffer layer 3 n-type ZnMgSSe cladding layer 4 n-type ZnSSe optical waveguide layer 5 Zn _1-x Cd _x O _y S _1-y active layer 6 p-type ZnSSe optical waveguide layer 7 p-type ZnMgSSe Cladding layer 8 p-type ZnSe contact layer 9 p-type ZnSe / ZnTe MQW layer 10 p-type ZnTe contact layer 11 insulating layer 12 p-side electrode 13 n-side electrode

Claims (18)

[Claims] 1. At least one type II element selected from the group consisting of Zn, Mg, Cd, Hg and Be and at least one type VI selected from the group consisting of Se, S, Te and O. A semiconductor light emitting device using a II-VI group compound semiconductor composed of a group element, wherein at least the lattice constant of the active layer substantially matches the lattice constant of the substrate. 2. The II- containing at least O in the active layer.
A compound semiconductor of Group VI, characterized in that
The semiconductor light-emitting device according to claim 1. 3. The active layer comprises at least Zn, Cd, O.
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is made of Se and Se. 4. The semiconductor light emitting device according to claim 1, wherein the active layer is made of Zn, Cd, O and S. 5. The semiconductor light emitting device according to claim 1, wherein the active layer is made of Zn, O and Se. 6. An emission wavelength of 380 nm to 620 nm
The semiconductor light emitting device according to claim 3, wherein 7. The emission wavelength is 380 nm to 540 nm
5. The semiconductor light emitting device according to claim 4, wherein 8. The semiconductor light emitting device according to claim 3, wherein the substrate is made of GaAs. 9. The semiconductor light emitting device according to claim 4, wherein the substrate is made of GaAs. 10. The semiconductor light emitting device according to claim 5, wherein the substrate is made of GaAs. 11. The semiconductor light emitting device according to claim 3, wherein the substrate is made of InP. 12. The semiconductor light emitting device according to claim 4, wherein the substrate is made of InP. 13. The semiconductor light emitting device according to claim 3, wherein the substrate is made of GaP. 14. The semiconductor light emitting device according to claim 4, wherein the substrate is made of GaP. 15. The semiconductor light emitting device according to claim 5, wherein the substrate is made of GaP. 16. The semiconductor light emitting device according to claim 3, wherein the substrate is made of ZnSe. 17. The semiconductor light emitting device according to claim 4, wherein the substrate is made of ZnSe. 18. The semiconductor light emitting device according to claim 5, wherein the substrate is made of ZnSe.