JPH0786683A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser made of a wide gap II-IV compound semiconductor which makes it possible to embody current construction structure and lower working voltage and provide high reliability and high light emission efficiency. CONSTITUTION:A semiconductor laser comprises a double heterostructure unit with buffer layers 12 to 15, which include In or Ga which has formed a growth on a p-GaAs substrate 11 and a p-Z buffer layer 16 laminated and formed on the buffer layers 12 to 15 and an undoped CdZnSe multiple quantum well active layer 18 and an n-ZnSSe clad layer 20. On a part of the surface of the substrate is formed a surface slanted by 15 deg. in the direction to [011] from a plane (100). The concentration of carriers of the p clad layer 16 on the slanted surface is arranged to be larger than that of the p clad layer 16 on the surface (100).

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 using a compound semiconductor material, and more particularly to a semiconductor light emitting device in which current confinement is performed by utilizing a plane direction of a substrate.

[0002]

2. Description of the Related Art In recent years, Zn has been used as a blue light emitting device material.
II-VI group compound semiconductors such as Se, ZnCdSe, and ZnSSe have attracted attention. Fig. 8 shows an example of the structure of a blue laser using this type of compound semiconductor material (MAHa
sse, Appl.phys, Letter No. 59p1272 (1991)).

In FIG. 8, reference numeral 81 is an n-GaAs substrate, and the n-GaAs buffer layer 8 is formed on the substrate 81.
2, n-ZnSe layer 83, n-ZnSSe cladding layer 8
4, n-ZnSe guide layer 85, CdZnSe quantum well active layer 86, p-ZnSe guide layer 87, p-ZnSS
An e-clad layer 88 and a p-ZnSe layer 89 are sequentially grown and formed. A striped Au electrode 91 is deposited on the p-ZnSe layer 89 by depositing Au through a polyimide film 90 having a striped opening. An In electrode 80 is formed on the back surface of the n-GaAs substrate 81.

In such a laser structure, by injecting a current from the Au electrode 91, continuous laser oscillation can be obtained at 77K. However, the current injected from the Au electrode 91 causes the p-ZnSe layer 89, p-ZnSS
There is a problem that the current cannot be sufficiently confined by being diffused by the e-cladding layer 88 and the p-ZnSe guide layer 87. This problem raises the threshold current of laser oscillation and makes it difficult to operate at room temperature or higher. Note that reducing the oscillation threshold current is very important from the viewpoint of reducing the operating current and improving the life characteristics.

In order to solve this problem, for example, GaA
In a laser using a III-V group compound semiconductor such as 1As, a ridge is formed in a p-cladding layer, and an n-type layer is regrown on the ridge to form a structure for current confinement. Has been realized. However, in a laser using a II-VI group compound semiconductor, a process for forming a ridge has not been established and it is difficult to regrow on the ridge. It is difficult to create a structure for current constriction as described above.

Further, in the laser structure shown in FIG. 8, the operating voltage is high, and continuous oscillation at room temperature and high luminous efficiency of LEDs, which are indispensable as a practical semiconductor laser, have not been realized so far. The reason why the operating voltage is extremely high in the semiconductor light emitting device using the II-VI group compound semiconductor is that the wide gap II-VI group semiconductor such as ZnSe which is not a problem in the conventional III-V group semiconductor is used as described below. This is because there is a problem peculiar to the light emitting element. That is, p
For those having a p-type conductivity type, such as type ZnSe,
This means that a large voltage drop can be forced when injecting current through a metal electrode or a heterojunction with another semiconductor.

As shown in FIGS. 9 (a) and 9 (b),
This is an essential problem in wide-gap II-VI group compound semiconductors such as ZnSe that a Schottky barrier with a metal and a heterobarrier with another semiconductor become large. In particular, when p-ZnSe was directly formed on the p-GaAs substrate, the hetero barrier became large as shown in FIG. 9B, and a large voltage drop was generated. In order to reduce such a hetero barrier, as shown in FIG.
In with a band gap intermediate between aAs and ZnSe
Although it has been proposed to use a GaP layer or the like (Japanese Patent Application No. 4-16258), it has not been examined how each carrier concentration of InGaP and ZnSe affects the heterobarrier.

[0008]

As described above, the conventional II-
The laser using the group VI compound semiconductor has a problem that the current is not sufficiently confined and the oscillation threshold current increases. Further, since the hetero barrier exists, the voltage drop is large, and the room temperature continuous oscillation and high reliability of the laser have not been achieved.

The present invention has been made in consideration of the above circumstances. An object of the present invention is to realize a current constriction structure capable of effectively confining an injected current, which has a low operating voltage. An object of the present invention is to provide a semiconductor light emitting device using a wide-gap II-VI group compound semiconductor, which has high reliability and high luminous efficiency.

[0010]

The essence of the present invention is to control the voltage drop due to the heterobarrier to effect current confinement by changing the carrier concentration of the II-VI group compound semiconductor layer in contact with the buffer layer. .

That is, the present invention comprises a buffer layer grown and formed on a single crystal substrate, and a II-VI group compound semiconductor layer formed on the buffer layer and forming a heterojunction with the layer. In the semiconductor light emitting device, the II-VI group compound semiconductor layer in contact with the buffer layer has a carrier concentration higher than that of the portion where the current confinement is performed, except for a portion where the current confinement is performed. It is characterized in that the hetero barrier between the group VI compound semiconductor layers is lowered.

Here, the following are preferred embodiments of the present invention. (1) The buffer layer contains at least In or Ga as a constituent element and has a band gap intermediate between the substrate and the II-VI group compound semiconductor layer. When GaAs is used as the substrate, the buffer layer should be InGaP, InGaAlP, or InAlP. (2) The substrate is [01] and [01]
1] or [01-1] direction and a surface inclined within a range of 10 to 40 degrees, and the current confinement is performed by this inclined surface, which is on the surface inclined from the (100) surface. The carrier concentration of the compound semiconductor layer is made higher than that of the compound semiconductor layer on the (100) plane. (3) ZnSe, ZnC as the II-VI group compound semiconductor layer
Using dSe and ZnSSe. (4) The buffer layer is p-type, and the II-VI group compound semiconductor layer on the buffer layer side is p-type doped with N (nitrogen) as an impurity.

[0013]

[Operation] InGa using Zn or Be as a dopant
In the growth of the AlP layer, GaA having a (100) plane orientation
s when grown on a substrate and from the (100) plane to [01
GaA having a plane orientation inclined in the [1] or [01-1] direction
The carrier concentration is different when grown on the s substrate. For example, InGaAlP grown on a substrate using Zn as a dopant and having a plane orientation inclined by 15 ° in the [011] direction from the (100) plane is about four times as large as when grown on a (100) GaAs substrate. It is known that a carrier concentration of (J. Crystal Growth 113 (199
1) pp.127-130).

The present inventors have examined whether such a phenomenon can be caused in a II-VI group compound semiconductor as well, and as a result, the carrier concentration of N-doped p-type ZnSe is larger due to the plane orientation of the single crystal substrate. Different things, and In and G
It has been found that the hetero barrier between the buffer layer containing a and the II-VI group compound semiconductor changes greatly depending on the carrier concentration of the II-VI group compound semiconductor layer. That is, N
The carrier concentration of doped p-type ZnSe is higher when it is formed on a plane inclined from (100) to the [011] direction or the "01-1" direction than when it is formed on the (100) plane. It was found that the higher the p-type ZnSe carrier concentration, the smaller the heterobarrier between the p-type ZnSe and the buffer layer.

In the present invention, this phenomenon is utilized and II-
In order to change the carrier concentration of the group VI compound semiconductor layer, the plane orientation of the single crystal substrate is partially changed, and by providing a region where the carrier concentration is higher and the heterobarrier is reduced than the other parts, the effective current Therefore, the threshold current can be reduced, and the reliability and the luminous efficiency can be improved.

[0016]

First, the basic principle of the present invention will be described before describing the embodiments. As described above, according to the present invention, the carrier concentration of N-doped p-type ZnSe newly discovered by the inventors of the present invention is greatly different depending on the plane orientation of the single crystal substrate, and the buffer containing In and Ga is present. It was made paying attention to the fact that the heterobarrier between the layer and the II-VI group compound semiconductor changes greatly depending on the carrier concentration of the II-VI group compound semiconductor layer.

FIG. 4 shows the difference in carrier concentration of N-doped p-type ZnSe depending on the plane orientation. N-doped ZnSe
Were grown using a molecular beam epitaxial method (MBE method). Although N ₂ was used as the N doping source, it is excited by utilizing discharge by a high frequency (RF).
The N ₂ flow rate was 0.1 sccm. Excited nitrogen increases as the output of the RF power source increases. The carrier concentration increases as the output of the RF power source increases, but at the same RF output, G tilted by 15 ° from (100) to the [011] direction compared to when grown on a (100) GaAs substrate.
Higher carrier concentration is obtained when ZnSe is grown on the aAs substrate. This is 15 ° from the (100) plane
This is because the rate of incorporation of N is high in the inclined surface.

As can be seen from FIG. 4, when the RF output is 150 W, for example, ZnSe on a (100) GaAs substrate is used.
Has a carrier concentration of 1 × 10 ¹⁷ cm ⁻³ ,
1 × 10 ¹⁸ cm on a substrate tilted by 15 ° in the 1] direction
A carrier concentration of ^-3 or more is obtained. The difference in carrier concentration depending on the plane orientation was the same not only in ZnSe but also in ZnSSe. Further, as shown in FIG. 5, the increase in the incorporation rate of N was remarkably observed in the substrate having the plane orientation inclined from 10 ° to 40 ° in the [011] direction. In addition, [01
Similarly, an increase in the N uptake rate was also observed in the [-1] direction.

Next, the hetero barrier between the buffer layer and ZnSe changes depending on the carrier concentration of each layer, and the current-
The influence on the voltage (IV) characteristic will be described. Figure 6
Pn of ZnSe with p-type InAlP as a buffer layer
The IV characteristic in junction is shown. The carrier concentration of p-type InAlP was kept constant at 1 × 10 ¹⁸ cm ^−3, and p-type ZnSe
Carrier concentration of 1 × 10 ¹⁷ , 2 × 10 ¹⁷ , 5 × 1
It was changed to 0 ¹⁷ , 1 × 10 ¹⁸ cm ⁻³ . As the carrier concentration of p-type ZnSe decreases, the voltage drop due to the hetero barrier increases, so that the IV characteristics deteriorate.

For example, when a voltage of 3 V is applied, p-type Zn
When the concentration of Se is 1 × 10 ¹⁸ cm ⁻³ , it is 2 to 3 × 10.
A current density of ³ A / cm ³ is obtained. This is a sufficient current density to obtain the oscillation of the laser. On the other hand, p-type Zn
When the carrier concentration of Se is 1 × 10 ¹⁷ cm ⁻³ , the current density is 5 × 10 A / cm ^2, which is 1/40 to 1/60 or less of 1 × 10 ¹⁸ cm ⁻³ .

In FIG. 7, the concentration of p-type ZnSe is 1 × 10 ^18.
The carrier concentration of p-type InAlP is set to 1 with a constant cm ^-3.
× 10 ¹⁷ , 2 × 10 ¹⁷ , 5 × 10 ¹⁷ , 1 × 10 ¹⁸ cm ^-3
At the pn junction of ZnSe when changed to
The V characteristic is shown. When the voltage is 3 V and the carrier concentration of p-type InAlP is 1 × 10 ¹⁸ cm ⁻³ , the current density is 2 to
It is 3 × 10 ³ A / cm ² . When it is 1 × 10 ¹⁷ cm ⁻³ , it is 7 × 10 ² A / cm ^2, which is about 1/4 of that when it is 1 × 10 ¹⁸ cm ⁻³ .

Comparing FIG. 6 and FIG. 7, it was revealed that the size of the heterobarrier in the heterojunction of p-type InAlP and p-type ZnSe largely depends on the carrier concentration of p-type ZnSe. When the carrier concentration of p-type ZnSe is high, the current density required for laser oscillation can be obtained, but when the carrier concentration is low, the voltage drop due to the hetero barrier is large and the current density is very low.

The present invention has been made by paying attention to such a new finding, and in order to change the carrier concentration of the II-VI group compound semiconductor, the plane orientation of the substrate crystal is partially changed to form the hetero barrier. The gist is to control and perform current constriction. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the device structure of a semiconductor laser according to the first embodiment of the present invention. In the figure, 11 is a p-GaAs substrate, and on this substrate 11 a Be-doped p-GaAs layer 12 (for example, thickness 0.5 μm, carrier concentration 2 × 10 ¹⁸ cm ⁻³ ), Be-doped p-In _0.5 G.
a _0.5 P buffer layer 13 (thickness 0.2 μm), Be-doped p-In _0.5 (Ga _0.5 Al _0.5 ) _0.5 P buffer layer 14 (thickness 0.2 μm), Be-doped p-In _0.5 Al
_0.5 P buffer layer 15 (thickness 0.2 μm), N-doped p
-ZnSSe cladding layer 16 (thickness 2 μm), N-doped p-ZnSe guide layer 17 (thickness 0.5 μm), undoped CdZnSe multiple quantum well active layer 18 (well width 7.
5 nm, number of wells 3), Cl-doped n-ZnSe guide layer 19 (thickness 0.5 μm, carrier concentration 1 × 10 ¹⁸ cm
^-3 ), Cl-doped n-ZnSSe cladding layer 20 (thickness 2 μm, carrier concentration 1 × 10 ¹⁸ cm ⁻³ ), and Cl-doped n ⁺ -ZnSe contact layer 21 (thickness 0.2 μm,
A carrier concentration of 1 × 10 ¹⁹ cm ⁻³ ) is sequentially formed. Then, Au / A is formed on the back surface of the p-GaAs substrate 11.
The uZn electrode 10 and the Au / Ti electrode 22 are respectively deposited on the n ⁺ -ZnSe contact layer 21.

The p-GaAs substrate 11 is formed with a portion A in which the substrate surface orientation is changed in a stripe shape having a width of 7 μm. The surface orientation of this portion A is from the (100) plane to [01].
1] direction is inclined by 15 °. The plane orientation in the other portion B is the (100) plane. The laminated structure as shown in FIG. 1 is formed by using the MBE method, and after growing each of the layers 12 to 15 in the III-V group compound semiconductor growth chamber, II-VI via the ultra-high vacuum transfer chamber. It moved to the group compound semiconductor growth chamber and each layer of 16-21 was grown.

Usually, in a semiconductor layer containing Al such as InAlP, since Al is easily oxidized, an oxide film is formed after taking it out into the air, and therefore it is difficult to regrow ZnSe. However, by using the vacuum integrated process, even on the Al-containing semiconductor layer without pretreatment or heat treatment.
The II-VI group compound semiconductor layer can be grown and can be grown with good reproducibility.

P-ZnSSe layer 16 and p-ZnSe layer 1
Growth conditions for growing No. 7 are RF output 150 W, N
₂ Flow rate was 0.1 sccm. At this time, p-Z on the plane A inclined by 15 ° in the [011] direction from the (100) plane
The carrier concentrations of the nSSe layer 16 and the p-ZnSe layer 17 were both 1 × 10 ¹⁸ cm ⁻³ . On the other hand, p-ZnSSe layer 16 and p-ZnSe layer 1 on B having a (100) plane
The carrier concentration of No. 7 was 1 × 10 ¹⁷ cm ⁻³ .

In addition, p which is a buffer layer on the A surface
-InGaP layer 13, p-InGaAlP layer 14, p-
The carrier concentration of the InAlP layer 15 is 2 × 10 ¹⁸ , respectively.
The ^values were 2 × 10 ¹⁸ and 1 × 10 ¹⁸ cm ⁻³ . On the B side,
It was 5 * 10 <^17> , 5 * 10 < ¹⁷ >, 2.5 * 10 < ¹⁸ > cm <^-3> , respectively. The Cl-doped n-ZnSe layer 19, n-Z
The carrier concentration of the nSSe layer 20 does not depend on the plane orientation.
It was the same on the surface and the surface B.

A voltage was applied to the laser device having such a structure to inject a current. In the portion on the A surface, p-Zn
A high current density can be obtained because the carrier concentration of the SSe layer 16 and the p-ZnSe layer 17 is high and the heterobarrier is reduced, but the voltage drop due to the heterobarrier is large on the B surface and is 1/50 or less than that on the A surface. Only current flows. That is, by providing the portion A in which the plane orientation is changed in a stripe shape on the GaAs substrate 11, the current was effectively confined in the stripe portion A, and continuous oscillation at room temperature was achieved. The threshold current at room temperature was 40 mA, and continuous oscillation up to 80 ° C. was confirmed, and the practicability could be significantly improved.

Further, in this laser, as shown in FIG. 2, a (100) plane having a step is formed on the GaAs substrate 11 in the end face portion, and [011] in the portion other than the end face.
A surface inclined by 15 ° in the direction was formed in a stripe shape. Note that, in FIG. 2, (a) is a plan view showing the substrate surface before forming each of the layers 12 to 21, and (b) is an arrow X- of FIG.
X'sectional view, (c) is a sectional view taken along line YY 'of (a).

In such a laser, almost no current is injected into the end face having the (100) plane. Therefore, by using the structure in which the end face is not injected as shown in FIG. 2, there is no problem that the end face is deteriorated due to the current flowing through the end face portion and the life characteristic is significantly deteriorated, and the reliability can be improved. In an actual operation test, an oscillation operation of 1000 H or more was confirmed at 50 ° C., and high reliability was achieved.

As described above, according to this embodiment, p-GaA
By partially changing the plane orientation of the s substrate 11, II-VI group compound semiconductors formed on the buffer layers 12 to 15, particularly the p-ZnSSe cladding layer 16 and the p-Zn layer, are formed.
The carrier concentration of the Se guide layer 17 can be partially changed, and thus effective current confinement can be performed. Therefore, it is possible to reduce the oscillation threshold current and extend the life. Further, in the method according to the present embodiment,
If a portion whose plane orientation is changed is formed on the GaAs substrate 11 in advance, III-V group and II-
Current confinement can be achieved by continuously growing a group VI compound semiconductor. This is a great advantage in a semiconductor light emitting device using a II-VI group compound semiconductor, which is difficult to perform a process of forming a ridge and regrowth on a surface on which an oxide film is formed.

FIG. 3 is a sectional view showing the device structure of a surface emitting light emitting diode (LED) according to the second embodiment of the present invention. In the figure, 31 is a p-GaAs substrate, and on this substrate 31, a Be-doped p-GaAs layer 32 (thickness 0.5 μm, carrier concentration 2 × 10 ¹⁸ cm ⁻³ ), Be-doped p-In _0.5 Ga. _0.5 P buffer layer 33 (thickness: 0.
2 μm), Be-doped p-In _0.5 (Ga _0.5 Al)
_0.5 ) _0.5 P buffer layer 34 (thickness 0.2 μm), Be
Doped p-In _0.5 Al _0.5 P buffer layer 35 (thickness 0.2 μm), N-doped p-ZnSe cladding layer 36
(Thickness 0.2 μm), undoped CdZnSe quantum well active layer 38 (thickness 10 nm), Cl-doped n-ZnSe
Cladding layer 40 (thickness 2 μm, carrier concentration 1 × 10 ¹⁸
cm ^-3 ), Cl-doped n ⁺ -ZnSe contact layer 41
(Thickness: 0.2 μm, carrier concentration: 1 × 10 ¹⁹ cm ⁻³ ) are sequentially formed by the MBE method.

On the p-GaAs substrate 31, a (100) plane is formed in a portion C of φ50 μm, and the other portion D has a plane orientation inclined by 15 ° in the [011] direction.
An Au / AuZn electrode 3 is formed on the back surface of the p-GaAs substrate 31.
0 is worn. n ⁺ -ZnSe contact layer 41
Is processed to have a diameter of 50 μm directly above the C portion, and a Ti / Au electrode 42 is deposited thereon. p-ZnS
The growth conditions for growing the e-clad layer 36 were RF output of 150 W and N ₂ flow rate of 0.1 sccm. At this time, D
The p-ZnSe concentration on the plane was 1 × 10 ¹⁸ cm ⁻³ , but on the C plane it was 1 × 10 ¹⁷ cm ⁻³ . P-InGaP, p- as the buffer layers 33 to 35 on the D surface
The carrier concentrations of InGaAlP and p-InAlP were 2 × 10 ¹⁸ , 2 × 10 ¹⁸ and 1 × 10 ¹⁸ cm ⁻³ , respectively. 5 × 10 ¹⁷ , 5 × 10 ¹⁷ , 2.5 × on the C plane
It was 10 ¹⁷ cm ^-3 .

When a current is passed through the surface-emitting type LED having such a structure, the current flows efficiently while avoiding below the Ti / Au electrode 42 where light cannot be extracted, as shown by the arrow in FIG. Light is extracted. This is because the hetero-barrier of p-InAlP and p-ZnSe on the C-plane is large, making it difficult for current to flow. According to the experiment, this LED has a wavelength of 560 at a current of 20 mA.
A brightness of 5 cd was obtained in nm. In addition, the brightness of the LED is 1 cd or less when the portion in which the plane orientation is changed is not provided. Therefore, in this example, it was possible to achieve a significant improvement in luminous efficiency.

The present invention is not limited to the above embodiments. Although the MBE method was used for the growth of each layer in the examples, the present invention is not limited to this, and the metal organic chemical vapor deposition method (MOCV
Method D) may be used. Further, as the II-VI group compound semiconductor layer, ZnMgSSe, ZnTe, CdZnSe, Z
Other materials such as nMgCdSe can be used. Furthermore, although N is used as a dopant in the embodiment, O,
Similar effects can be obtained by using other dopants such as P, As and Li.

As a means for partially changing the carrier concentration, instead of partially changing the plane orientation of the substrate, II-
The group VI compound semiconductor layer may be partially heated. For example, in the case of a semiconductor laser, a stripe-shaped mask is provided on the II-VI group compound semiconductor layer, and laser light is irradiated from the upper surface of the mask to selectively heat a portion not covered with the mask, The carrier concentration in this portion can be lowered. In addition, various modifications can be made without departing from the scope of the present invention.

[0038]

As described in detail above, according to the present invention, the injected current can be effectively narrowed by partially changing the carrier concentration of the II-VI group compound semiconductor layer in contact with the buffer layer. A current constriction structure can be realized,
It is possible to realize a semiconductor light emitting device using a wide gap II-VI group compound semiconductor, which has a low operating voltage, high reliability, and high light emission efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view showing a device structure of a semiconductor laser according to a first embodiment.

2A and 2B are a plan view and a cross-sectional view for explaining the configuration of the end face portion of the laser according to the first embodiment.

FIG. 3 is a sectional view showing an element structure of a surface emitting LED according to a second embodiment.

FIG. 4 is a characteristic diagram showing a difference in carrier concentration of N-doped p-type ZnSe depending on plane orientation.

FIG. 5 is a characteristic diagram showing changes in the rate of incorporation of N with respect to the inclination of the substrate surface.

FIG. 6 is a characteristic diagram showing the carrier concentration dependence of IV characteristics of ZnSe pn junction on p-type InAlP.

FIG. 7 is a characteristic diagram showing the carrier concentration dependence of IV characteristics of a ZnSe pn junction on p-type InAlP in p-InAlP.

FIG. 8 is a sectional view showing an element structure of a conventional blue laser using a compound semiconductor material.

FIG. 9 is a schematic diagram showing a band structure at a junction between p-ZnSe and a metal or semiconductor.

[Explanation of symbols]

10, 30 ... Au / AuZn electrode 11, 31 ... p-GaAs substrate 12, 32 ... p-GaAs layer 12 13, 33 ... p-InGaP buffer layer 14, 34 ... p-InGaAlP buffer layer 15, 35 ... p-InAlP Buffer layer 16 ... p-ZnSSe clad layer 17 ... p-ZnSe guide layer 18 ... CdZnSe multiple quantum well active layer 19 ... n-ZnSe guide layer 20 ... n-ZnSSe clad layer 21, 41 ... n ⁺ -ZnSe contact layer 22, 40 ... Au / Ti electrode 36 ... p-ZnSe clad layer 38 ... CdZnSe quantum well active layer 40 ... n-ZnSe clad layer

Claims (2)

[Claims] 1. A semiconductor light emitting device comprising a buffer layer grown and formed on a single crystal substrate, and a II-VI group compound semiconductor layer which is heterojunction with the buffer layer laminated on the buffer layer. Of the II-VI group compound semiconductor layer in contact with the buffer layer, by making the carrier concentration of a portion other than the portion where the current constriction is performed larger than the portion where the current confinement is performed, the buffer layer and the II-VI A semiconductor light emitting device having a low hetero barrier between group compound semiconductor layers. 2. The substrate has a (100) plane and a plane inclined within a range of 10 to 40 degrees in the [011] or [01-1] direction from the (100) plane. 2. The current confinement is performed by the method of claim 1, wherein the carrier concentration of the compound semiconductor layer on the plane inclined from the (100) plane is made higher than that of the compound semiconductor layer on the (100) plane. Semiconductor light emitting device.