JP2003017738A - Epitaxial wafer for light emitting element, its manufacturing method, and light emitting element using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new light emitting element that can meet the demand for a low forward voltage while maintaining high power and a high-speed characteristic in an infrared LED. SOLUTION: An epitaxial wafer has a double heterostructure light emitting section composed of an n-type GaAlAs clad layer 20, a p-type GaAlAs active layer 21 having a light emitting wavelength of 850-900 nm, and a p-type GaAlAs clad layer 22. The clad layer 22 contains Mg as the main impurity and the surface carrier concentration of the layer 22 is adjusted to 1×10<18> -6×10<18> /cm<3> . In addition, the thickness of the layer 22 is adjusted to 5-30 μm and the oxygen concentration of the layer 22 is adjusted to <=3×10<16> /cm<3> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, particularly a high speed / light source used for optical communication and space transmission utilizing infrared light.
The present invention relates to fabrication of a high-power semiconductor light emitting device.

[0002]

2. Description of the Related Art Ga _1-X Al _X As (hereinafter referred to as GaAlAs
Abbreviated. ) A light-emitting device using a compound semiconductor (hereinafter,
Abbreviated as LED. ) Is widely used as a light source for infrared to red. Infrared LEDs are used for optical communication and space transmission, but as the capacity of data to be transmitted increases and the transmission distance increases, the demand for higher output and higher speed is increasing.

As is known in the art, GaAlA
In the s-based LED, the output of the light emitting element is higher when the light emitting portion having the double hetero structure (hereinafter, abbreviated as DH structure) is used than the single hetero structure, and further higher output can be obtained by removing the substrate. Has been planned. The type of DH structure from which the substrate is removed (hereinafter abbreviated as DDH structure), that is,
In an epitaxial wafer having a structure in which only the p-type clad layer, the p-type active layer and the n-type clad layer are epitaxially grown on the substrate and then the substrate is removed, the product thickness is reduced and Handling becomes difficult. At the same time, the height from the bottom surface to the pn junction of the light emitting device manufactured from this epitaxial wafer becomes low, and the paste for adhering the device to the conductor crawls up the side surface of the device, causing a short circuit of the pn junction. To do.

In order to prevent this, the fourth method for increasing the total thickness of the finished product after removing the substrate and the distance from the element bottom surface to the junction.
Adding an epitaxial layer of
The H structure has a standard configuration. The fourth epitaxial layer has a bandgap wider than that of the active layer and is designed not to absorb light emitted from the active layer.

This fourth epitaxial layer is formed from the above-mentioned DH.
The structure may be added to the n-type clad side or the p-type clad side. Furthermore, the fourth epitaxial layer does not have to be a single layer, and a plurality of epitaxial layers may be combined.

[0006]

Infrared LEDs for optical communication and space transmission are used in battery-powered portable terminals, and a large current must be sent to send information farther. Therefore, along with high output and high speed characteristics, the demand for low forward voltage is increasing.

The resistance of the LED, which is a factor that determines the forward voltage of the LED, is divided into the resistance of the semiconductor crystal itself and the contact resistance between the semiconductor crystal and the electrode. GaAs-AlA
In the s-based semiconductor, the resistance of the crystal itself is 10 times or more higher in the mobility of electrons than in the holes, so that if the carrier concentration and Al composition are the same, the resistance of the n-type layer is lower and p
The mold layer has higher resistance. The contact resistance between the semiconductor crystal and the electrode depends on the Al composition and carrier concentration of the crystal in the portion in contact with the electrode. In order to lower the forward voltage of the LED, it is necessary to lower the resistance of the p-type layer.

In the liquid phase epitaxial growth method, which is a general method for manufacturing LEDs for optical communication and space transmission, GaA is used.
Zn is usually used as the p-type dopant of 1As. However, when Zn is heavily doped to reduce the resistance of the p-type GaAlAs layer, the carrier concentration of the GaAlAs layer increases and the forward voltage decreases, but self-absorption of light emission due to high doping occurs and the output of the LED decreases. Resulting in. Further, when Zn is used for the p-type clad layer, Zn having a low diffusion energy traverses the active layer and diffuses into the n-type layer, and the pn junction position shifts from the metallurgical interface into the n-type clad layer having a large band gap. . This phenomenon is L
It is disadvantageous for realizing a low forward voltage of ED.
It is an object of the present invention to produce a new light emitting element that can satisfy the requirement of low forward voltage while maintaining high output and high speed characteristics in infrared LEDs mainly used for optical communication and space transmission.

[0009]

The inventor of the present invention diligently studied reduction of the forward voltage of the above-mentioned infrared LED (reduction of VF). As a result, especially in the epitaxial wafer for light emitting device using the GaAlAs compound semiconductor, p
By making Mg the main impurity in the type GaAlAs clad layer and controlling the carrier concentration thereof, it is possible to achieve a low VF without lowering the output of the LED.
The inventors have found that the p-type layer thickness and oxygen atoms have a great influence on the light emission output of the LED, and have completed the present invention.

That is, the present invention provides: (1) n-type Ga _1-X1 Al _X1 As clad layer (0 <X1 <
1) and a p-type Ga _1-X2 Al _X2 As active layer (0 <X2 <
1) and a p-type Ga _1-X3 Al _X3 As clad layer (0 <X3
<1) is sequentially laminated, and a light emitting element epitaxial wafer having a double heterostructure light emitting portion is provided.
The main impurity of the Ga _{1 -X3} Al _X3 As clad layer is Mg.
And the surface carrier concentration of the p-type Ga _{1-X 3} Al _X3 As clad layer is within the range of 1 × 10 ^{18 to} 6 × 10 ¹⁸ / cm ³ . (2) The light emitting device as described in (1) above, wherein the surface carrier concentration of the p-type Ga _{1 -X 3} Al _X3 As cladding layer is in the range of 1 × 10 ^{18 to} 3 × 10 ¹⁸ / cm ^3. Epitaxial wafer. (3) The p-type Ga _1-X3 Al _X3 As clad layer has a thickness of 5 μm.
m or more and 30 μm or less, the above (1)
Alternatively, the epitaxial wafer for a light emitting device according to (2). (4) The epitaxial wafer for a light emitting device as described in (1) to (3) above, wherein the p-type Ga _{1 -X3} Al _X3 As cladding layer has an oxygen concentration of 3 × 10 ¹⁶ / cm ³ or less. . (5) p-type Ga of n-type Ga _1-X1 Al _X1 As clad layer
(1) to (4) above, wherein one or more n-type GaAlAs layers are formed on the surface opposite to the side where the _1-X2 Al _X2 As active layers are laminated. Epitaxial wafer for devices. Is.

The present invention also provides (6) the p _- type electrode provided in contact with the surface of the p-type Ga _{1 -X3} Al _X3 As clad layer. A light emitting device produced using the epitaxial wafer for a light emitting device according to any one of claims. (7) A p _- type electrode is provided in contact with the surface of the p-type Ga _1-X3 Al _X3 As clad layer, and n-type Ga _1-X1 Al _X1 As is formed.
A light-emitting device produced using the epitaxial wafer for a light-emitting device according to (5) above, wherein an n-type electrode is provided in contact with the surface of the n-type GaAlAs layer formed on the surface of the clad layer. (8) The light emitting device according to (6) or (7), which has an emission wavelength in the range of 850 to 900 nm. Is.

Further, according to the present invention, (9) the n-type Ga _{1 -X1} Al _X1 As cladding layer (0 <X1 is formed on the GaAs substrate by the liquid phase epitaxial growth method.
<1) and a p-type Ga _1-X2 Al _X2 As active layer (0 <X2 <
1) and a p-type Ga _1-X3 Al _X3 As clad layer (0 <X3
In the method for manufacturing an epitaxial wafer for a light emitting device, in which <1) is sequentially laminated to form a light emitting portion having a double hetero structure, Mg is added as an impurity during the growth of the p-type Ga _{1 -X3} Al _X3 As clad layer, The surface carrier concentration of the p-type Ga _1-X3 Al _X3 As clad layer is set to 1 × 10 ^{18 to} 6 × 10 ^18.
A method for manufacturing an epitaxial wafer for a light-emitting device, characterized by controlling within a range of / cm ³ . (10) Emission according to (9) above, wherein the surface carrier concentration of the p-type Ga _{1-X 3} Al _X3 As cladding layer is controlled within the range of 1 × 10 ^{18 to} 3 × 10 ¹⁸ / cm ^3. Manufacturing method of epitaxial wafer for device. (11) The thickness of the p-type Ga _1-X3 Al _X3 As clad layer is 5
The method for producing an epitaxial wafer for a light emitting device according to (9) or (10) above, wherein the thickness is not less than 30 μm and not more than 30 μm. (12) The epitaxial wafer for a light-emitting device as described in (9) to (11) above, wherein the oxygen concentration in the p-type Ga _1-X3 Al _X3 As clad layer is 3 × 10 ¹⁶ / cm ³ or less. Manufacturing method. Is.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be described below.
Explain. Fig. 1 shows the present invention used for manufacturing infrared emitting LEDs.
Schematic structure of the epitaxial wafer for light emitting device
Show. On the epitaxial wafer for light emitting device shown in FIG.
And each epitaxial layer is an n-type GaAs single crystal substrate
On the first n-type GaAlAs layer 2, second n-type GaA
lAs layer 3, n-type Ga_1-X1Al_X1As clad layer 4 (0
<X1 <1), p-type Ga_1-X2Al _X2As active layer 5 (0 <
X2 <1), and p-type Ga_1-X3Al_X3As clad layer 6
The layers are stacked in the order of (0 <X3 <1).

Regarding the Al mixed crystal ratio of each epitaxial layer, the active layer 5 is selected so that the emission wavelength is 850 to 900 nm, and the first n-type layer 2, the second n-type layer 3 and the n-type clad are formed. The layer 4 and the p-type cladding layer 6 are selected so that the bandgap is wider than that of the active layer 5 so as not to absorb the light emitted from the active layer 5. Te is used as the dopant for the first n-type layer 2, the second n-type layer 3, and the n-type cladding layer 4, Ge is used as the dopant for the p-type active layer 5, and Mg is used as the dopant for the p-type cladding layer 6. . Here, the amount of Ge doped into the active layer is selected so that the emission intensity and the response speed of the light emitting element are optimized.

The epitaxial wafer for light emitting device of the present invention is preferably manufactured by a liquid phase epitaxial growth method. For the liquid phase epitaxial growth, for example, a slide boat type growth apparatus as shown in FIG. 2 can be used. In the jig of the slide boat type growth apparatus shown in FIG. 2, the n-type GaAs substrate 7 is set in the substrate storage groove 8 of the slider 9. GaAs is used for the slide boat body 10.
Arrange crucibles according to the number of layers to be grown on the substrate 7,
In the crucible, a Ga metal, a metal Al, and a GaAs polycrystal having a composition suitable for growing the epitaxial layer and a dopant suitable for realizing the conductivity type and the carrier concentration of each epitaxial layer are compounded.

Further, in the slide boat jig shown in FIG. 2, the inside of the substrate storage groove 8 and the inside of the crucibles 11 to 15 are coated with glassy carbon.
It is preferable that the portion in direct contact with the solution is coated with glassy carbon, and that the crucible lid 16 is made of glassy carbon. (In FIG. 2, the hatched portion indicates a portion coated with glassy carbon or a glassy carbon product.)

In the production of the light emitting device of the present invention, each GaAl as shown in FIG. 1 is formed on a GaAs substrate by the liquid phase epitaxial growth method using the growth apparatus having the above structure.
After epitaxially growing the As layer, the epitaxial wafer is taken out, the surface of the p-type GaAlAs cladding layer is protected by an acid resistant sheet, and the GaAs substrate is selectively removed by an ammonia-hydrogen peroxide-based etchant. Then, a p-type electrode and an n-type electrode made of gold are formed on both surfaces of the p-type GaAlAs clad layer surface and the first n-type GaAlAs layer surface of the epitaxial wafer, and the epitaxial wafer is separated into element shapes by dicing. It is possible to manufacture an infrared emitting LED in which the p-type GaAlAs clad layer is on the front surface side.

Since the infrared LED obtained by the present invention has a high light emission output, it can be suitably used for a light emitting element for transmission used in an optical communication device or a space transmission device utilizing infrared rays. The optical communication device and the space transmission device incorporating the infrared LED of the present invention are suitable for large capacity data transfer and long distance data transfer.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 In Example 1, an epitaxial wafer for a light emitting device having the laminated structure shown in FIG. 1 was prepared. Each GaAl of epitaxial wafer for light emitting device
The epitaxial growth of the As layer is performed by coating the inside of the substrate storage groove and the crucible described above with glassy carbon,
The slide boat type growth apparatus shown in FIG. 2 using a lid made of glassy carbon was used.

The epitaxial wafer for light emitting device was manufactured as follows. An n-type GaAs substrate was set in the substrate storage groove of the slide boat growth apparatus, and Ga metal, GaAs polycrystal, metal Al, and a dopant were added to each crucible at the time of performing epitaxial growth in the composition shown in Table 1 below. It was

[0022]

[Table 1]

A slide boat type growth apparatus in which these raw materials were set was set in a quartz reaction tube (not shown) and heated to 950 ° C. in a hydrogen stream to dissolve the raw materials. Subsequently, the ambient temperature was lowered to 915 ° C., the slider 9 was pushed to the right, the n-type GaAs substrate 7 was moved to below the crucible 11 and brought into contact with the raw material solution (melt). Next, the ambient temperature is lowered at a rate of 0.5 ° C./minute to make the n-type GaA
The first n-type GaAlAs layer 2 shown in FIG. 1 was grown on the s substrate. After the system temperature reached 870 ° C., the slider 9 was pushed again to separate it from the first melt and bring it into contact with the second melt. Hereinafter, in the same procedure as above, the second GaAlAs layer 3, the n-type GaAlAs cladding layer 4, and the p-type GaAlAs having different Al mixed crystal ratios were used in the temperature ranges shown in Table 2 below.
The active layer 5 and the p-type GaAlAs cladding layer 6 were sequentially grown.

[0024]

[Table 2]

In Example 1, in order to change the carrier concentration level of the p-type GaAlAs cladding layer 6, the amount of Mg added per kg of Ga metal was 0.03 to 0.3.
g was changed, and the other conditions were the same as the growth method described above, and the production of the epitaxial wafer was repeated. As a result, an epitaxial wafer was obtained in which the surface carrier concentration of the p-type GaAlAs cladding layer was 8 × 10 ¹⁷ to 8 × 10 ¹⁸ / cm ³ .

After completion of the epitaxial growth, the epitaxial wafer was taken out, the surface of the p-type GaAlAs cladding layer 6 in FIG. 1 was protected with an acid resistant sheet, and the n-type GaAs substrate 1 was selectively removed with an ammonia-hydrogen peroxide based etchant. . Then, p-type GaAs of the epitaxial wafer
A p-type electrode and an n-type electrode made of gold are formed on both surfaces of the 1As clad layer surface and the first n-type GaAlAs layer surface, and an epitaxial wafer is formed into 40 by dicing.
An LED having a structure shown in FIG. 3 was produced by separating the element into a 0 μm square element shape. In FIG. 3, 17 is an n-type electrode, 1
8 is the first n-type GaAlAs layer, and 19 is the second n-type Ga
AlAs layer, 20 is n-type GaAlAs clad layer, 21
Is a p-type GaAlAs active layer, 22 is a p-type GaAlAs cladding layer, and 23 is a p-type electrode.

Comparative Example 1 An epitaxial wafer for a light emitting device was manufactured under the same conditions as in Example 1. However,
In the wafer manufactured in Comparative Example 1, Zn was the main impurity in the p-type GaAlAs cladding layer. Then, using the produced epitaxial wafer, an LED was produced in the same manner as in Example 1.

FIG. 4 shows the relationship between the surface carrier concentration of the p-type GaAlAs cladding layers of the LEDs obtained in Example 1 and Comparative Example 1 and the emission output, and FIG. 5 shows the relationship between Example 1 and Comparative Example 1. The relationship between the surface carrier concentration of the p-type GaAlAs clad layer of the LED and the forward voltage (VF) is shown.

As is apparent from FIG. 4, p-type GaAlA
If major impurities s clad layer is Mg, in the range surface carrier concentration of ^{8 × 10 17 ~3 × 10 18} / cm 3 is a light emitting output is constant, 3 × exceeding 10 ¹⁸ / cm ³ and the light-emitting output Fell below the target output when it exceeded 6 × 10 ¹⁸ / cm ³ . On the other hand, for VF, p-type GaA
When the main impurity of the 1As clad layer was Mg, it decreased as the surface carrier concentration increased, as can be seen from FIG. The VF value in FIG. 5 indicates the VF (at a forward current of 500 mA) of an LED with a chip size of 400 μm square, and the standard chip size of 400 μm square LE
Considering the practicality of D, VF (at a current of 500 mA)
Is preferably 2.2 V or less, and therefore p-type Ga
The surface carrier concentration of the AlAs clad layer is 1 × 10 ¹⁸ /
It is desirable to set it to cm ³ or more.

On the other hand, when Zn was used as the main impurity of the p-type GaAlAs cladding layer, as is apparent from FIG. 4, the emission output decreased when the surface carrier concentration became 2 × 10 ¹⁸ / cm ³ or more. Further, as can be seen from FIG. 5, VF decreased as the surface carrier concentration increased.

When the GaAlAs layer is epitaxially grown using the liquid phase epitaxial growth method of the slow cooling method, the carrier concentration distribution in the layer differs depending on the element used as the dopant. When the dopant is Mg, the segregation coefficient increases as the growth temperature decreases, so that the carrier concentration increases as the growth proceeds, and the carrier concentration at the growth end portion becomes the highest. P-type GaAl grown in Example 1
In the case of the As clad layer, the carrier concentration at the interface with the active layer, which is the growth start portion, is the lowest, and the carrier concentration on the surface forming the electrode is high, so the contact resistance with the electrode can be lowered and the forward direction It leads to the reduction of voltage.

On the other hand, when the dopant is Zn, there is almost no change in the segregation coefficient with respect to temperature changes, so the carrier concentration in the epitaxial layer is almost constant. In order to increase the carrier concentration in the part that contacts the electrode, p-type G
When Zn is doped at high concentration in the aAlAs clad layer,
Since the entire epitaxial layer has a high carrier concentration, a decrease in output due to high doping and diffusion into the n-type cladding layer are likely to occur, which is disadvantageous in decreasing a forward voltage.

From Example 1 above, the main impurity of the p-type GaAlAs cladding layer was Mg, and the surface carrier concentration was in the range of 1 × 10 ^{18 to} 6 × 10 ¹⁸ / cm ³ , preferably 1 × 10 ^{18 to} 3 ×. It was found that a high output LED with a low VF can be obtained by setting it within the range of 10 ¹⁸ / cm ³ .

Example 2 Further, based on the results of Example 1, p-type GaAlAs is formed under the condition that the surface carrier concentration of the p-type GaAlAs cladding layer is 3 × 10 ¹⁸ / cm ^3.
By changing the layer thickness of the clad layer within a range of 2 to 41 μm,
Other than that, an epitaxial wafer for a light-emitting element was grown under the same conditions as in Example 1, and LED production was repeated.

FIG. 6 shows the relationship between the layer thickness of the p-type GaAlAs clad layer of the LED obtained in Example 2 and the light emission output. As is clear from FIG. 6, it was found that the light emission output was improved when the layer thickness of the p-type GaAlAs cladding layer was 30 μm or less. Furthermore, it was confirmed that the output increased as the layer thickness became thinner. However, it was also confirmed that the output decreased when the layer thickness was 5 μm or less. Therefore, p-type G
It was found that the LED has a high output by setting the layer thickness of the aAlAs clad layer within the range of 5 μm or more and 30 μm or less, preferably within the range of 10 to 20 μm.

Example 3 In the present invention, p-type GaAlA is used.
the oxygen concentration of the s cladding layer is required to be ³ × 10 ¹⁶ / cm 3 or less, but in order to suppress the oxygen concentration in the p-type GaAlAs cladding layer reproducibly in ³ × 10 ¹⁶ / cm 3 or less, It is preferable to take the oxygen concentration reduction measures shown in. That is, the GaAs single crystal substrate and the GaAs polycrystal used for epitaxial growth are subjected to etching treatment before use, and then sufficiently washed with ultrapure water and dried. Further, the hydrogen gas and the argon gas that form the atmosphere for epitaxial growth are purified by using a commercially available high-purity gas using a refining device, and then supplied to the reaction furnace. Regarding the slide boat type growth device made of graphite,
The portion that is in direct contact with the raw material is made of glassy carbon or is coated with glassy carbon, and a baking treatment is further performed at 900 ° C. or higher to sufficiently remove the moisture adhering to the growth apparatus.

In Example 3, the production of the epitaxial wafer having the above oxygen concentration reduction measures was repeated several times. As a result of implementing the measures for reducing the oxygen concentration as described above, the p-type GaAlA of the epitaxial wafer obtained was obtained.
The oxygen concentration of the s clad layer is 3 × 10 ¹⁶ / cm
It was ³ or less. The p-type Ga produced in Example 3 was used.
The surface carrier concentration of the AlAs clad layer is 3 × 10 ¹⁸ /
cm ³ , and the layer thickness was 15 μm.

(Comparative Example 2) In Comparative Example 2, a measure for reducing the oxygen concentration described in Example 3 above, that is,
Epitaxial wafers were produced several times without performing the etching treatment before the use of GaAs polycrystal, the washing with ultrapure water, the drying treatment and the purification treatment of the atmosphere gas to be used. As a result, p-type GaAlA of the obtained epitaxial wafer
The oxygen concentration in the s clad layer is all 4 × 10 ¹⁶ / cm ³
That was all. The p-type GaA produced in Comparative Example 2 was used.
The surface carrier concentration of the 1As clad layer is 3 × 10 ¹⁸ / c
m ³ and the layer thickness was 15 μm.

FIG. 7 shows the relationship between the oxygen concentration in the p-type GaAlAs clad layer of the LEDs produced in Example 3 and Comparative Example 2 and the emission output. From this result, p-type GaA
It was clarified that a light emission output higher than the target output can be obtained by setting the oxygen concentration of the 1As clad layer to 3 × 10 ¹⁶ / cm ³ or less.

[0040]

As described above, according to the present invention, it is possible to provide an epitaxial wafer for producing a high-power infrared LED, and an infrared LED produced from this epitaxial wafer. In particular, p-type GaAlA
By making Mg the main impurity of the s clad layer and setting the surface carrier concentration within the range of 1 × 10 ^{18 to} 6 × 10 ¹⁸ / cm ³ , it has become possible to improve the light emission output and reduce the VF. . Further, by setting the layer thickness of the p-type GaAlAs clad layer within the range of 5 to 30 μm, it has become possible to further increase the output of the LED.

The infrared LED epitaxial wafer of the present invention enables high emission output of the infrared LED,
LE capable of supporting large-capacity data transmission and long-distance data transmission
It became possible to fabricate D. Especially the LED of the present invention
When is incorporated into optical communication and space transmission equipment, it has become possible to provide high-performance equipment that has never existed before.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of an epitaxial wafer for a light emitting device of the present invention.

FIG. 2 is a view showing a slide boat type growth apparatus used for liquid phase epitaxial growth.

FIG. 3 is a diagram showing a structure of an LED according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a surface carrier concentration of a p-type GaAlAs clad layer of an LED and a light emission output.

FIG. 5 is a diagram showing a relationship between a surface carrier concentration of a p-type GaAlAs clad layer of an LED and a forward voltage (VF).

FIG. 6 is a diagram showing a relationship between a layer thickness of a p-type GaAlAs clad layer of an LED and a light emission output.

FIG. 7 is a diagram showing the relationship between the oxygen concentration in the p-type GaAlAs cladding layer of the LED and the light emission output.

[Explanation of symbols]

1 n-type GaAs substrate 2 First n-type GaAlAs layer 3 Second n-type GaAlAs layer 4 n-type GaAlAs clad layer 5 p-type GaAlAs active layer 6 p-type GaAlAs clad layer 7 n-type GaAs substrate 8 substrate storage groove 9 slider 10 Slide boat body 11 crucibles 12 crucibles 13 crucibles 14 crucibles 15 crucibles 16 crucible lid 17 n-type electrode 18 First n-type GaAlAs layer 19 Second n-type GaAlAs layer 20 n-type GaAlAs clad layer 21 p-type GaAlAs active layer 22 p-type GaAlAs clad layer 23 p-type electrode

Claims (12)

[Claims] 1. n-type Ga_1-X1Al_X1As clad layer (0 <
X1 <1) and p-type Ga _1-X2Al_X2As active layer (0 <X
2 <1) and p-type Ga_1-X3Al_X3As clad layer (0 <
Double heterostructure light emission in which X3 <1) are sequentially stacked
Epitaxial wafer for light emitting device
And p-type Ga_1-X3Al_X3Main impurities of As clad layer
Is Mg and the p-type Ga is_1-X3Al_X3As clad
The surface carrier concentration of the layer is 1 × 10¹⁸~ 6 × 10¹⁸/ Cm
³Epitaxy for light-emitting devices characterized in that
Shull wafer. 2. A p-type Ga_1-X3Al_X3Surface of As clad layer
Carrier concentration is 1 × 10 ¹⁸~ 3 x 10¹⁸/ Cm³Range of
The light emitting element according to claim 1, wherein
Epitaxial wafer. 3. The epitaxial wafer for a light emitting device according to claim 1, wherein the p-type Ga _{1 -X3} Al _X3 As clad layer has a layer thickness of 5 μm or more and 30 μm or less. 4. The epitaxial wafer for a light emitting device according to claim 1, wherein the p-type Ga _{1 -X3} Al _X3 As cladding layer has an oxygen concentration of 3 × 10 ¹⁶ / cm ³ or less. 5. One or more n-type GaAlAs layers are formed on the surface of the n-type Ga _1-X1 Al _X1 As cladding layer opposite to the side where the p-type Ga _1-X2 Al _X2 As active layer is laminated. The epitaxial wafer for a light emitting device according to claim 1, wherein the epitaxial wafer is a light emitting device. 6. The light emitting device according to claim 1, wherein a p-type electrode is provided in contact with the surface of the p-type Ga _{1 -X3} Al _X3 As clad layer. A light emitting device manufactured using an epitaxial wafer. 7. A p-type electrode is provided in contact with the surface of the p-type Ga _1-X3 Al _X3 As clad layer, and n-type Ga _1-X1 Al is provided.
N-type GaAlAs formed on the surface of the _X1 As cladding layer
The light emitting device manufactured using the epitaxial wafer for a light emitting device according to claim 5, wherein an n-type electrode is provided in contact with the surface of the layer. 8. The light emitting device according to claim 6, which has an emission wavelength in the range of 850 to 900 nm. 9. A liquid phase epitaxial growth method is used to obtain Ga.
N-type Ga on As substrate _1-X1Al_X1As clad layer (0
<X1 <1) and p-type Ga_1-X2Al_X2As active layer (0 <
X2 <1) and p-type Ga_1-X3Al_X3As clad layer (0
<X3 <1) are sequentially stacked to form a light emitting portion having a double hetero structure.
Method for manufacturing epitaxial wafer for light emitting device for forming light emitting element
In, p-type Ga_1-X3Al_X3Growth of As clad layer
At this time, Mg was added as an impurity, and the p-type Ga_1-X3Al_X3
The surface carrier concentration of the As clad layer is 1 × 10¹⁸~ 6x
10¹⁸/ Cm³Is characterized by controlling within the range of
Method for manufacturing epitaxial wafer for optical device. 10. The surface carrier concentration of the p-type Ga _{1 -X3} Al _X3 As cladding layer is controlled within the range of 1 × 10 ^{18 to} 3 × 10 ¹⁸ / cm ³ . Method for manufacturing epitaxial wafer for light emitting device. 11. The method for producing an epitaxial wafer for a light emitting device according to claim 9, wherein the p-type Ga _{1 -X3} Al _X3 As clad layer has a layer thickness of 5 μm or more and 30 μm or less. 12. The epitaxial wafer for a light emitting device according to claim 9, wherein the oxygen concentration in the p-type Ga _{1 -X3} Al _X3 As clad layer is 3 × 10 ¹⁶ / cm ³ or less. Production method.