JPH06314818A - Manufacture of gaalas semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To provide a GaAlAs semiconductor light emitting element of high humidity resistance wherein high output can be acquired even if AlAs mixed crystal ratio is restricted in both sides of an element. CONSTITUTION:After growth melt solution 9 of a lower layer is brought into contact with a GaAs substrate 13 by partitioning a first bath 1a for forming a first clad layer in an epitaxial boat by a partition 4 up and down, a temperature is lowered by melt back and a GaAlAs first clad (a) layer of low AlAs mixed crystal ratio is formed in a growth starting surface of the GaAs substrate 13. Thereafter, the partition 4 is removed and growth melt solution 10 is brought into contact with the GaAs substrate 13 to form a conventional GaAlAs first clad layer (b) layer. Humidity resistance and high output are ensured regardless of AlAs mixed crystal ratio in both sides of an element after removal of the GaAs substrate 13 by forming the first clad layer to the two layers of the first clad (a) layer of low AlAs mixed crystal ratio and the first clad (b) layer of high AlAs mixed crystal ratio in this way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a GaAlAs semiconductor element capable of manufacturing a substrate-removable double hetero GaAlAs semiconductor light emitting element having high output and high reliability.

[0002]

2. Description of the Related Art In the case of forming a GaAlAs semiconductor light emitting device by using a slow cooling method, as shown in FIG.
On the As substrate, a GaAlAs first cladding layer, an active layer and a Ga
A second heterostructure is formed by sequentially and continuously performing liquid phase epitaxial growth of the AlAs second cladding layer. In this way, by effectively confining the carriers in the active layer region by utilizing the difference in the forbidden band, it is possible to more effectively obtain the desired wavelength light. Next, as shown in FIG. 3B, the GaAs substrate on the wafer after the growth is removed. By doing so, light can be extracted also from the back surface of the GaAsAlAs semiconductor light emitting element (the GaAsAs first cladding layer growth start surface).

[0003]

[Problems to be Solved by the Invention] However, the above G
The method for producing the aAs substrate-removed double hetero GaAlAs semiconductor light emitting device has the following problems. That is, as described above, the GaAs substrate-removable double hetero GaAlA
s When manufacturing a semiconductor light emitting device, in order to obtain a sufficient effect of confining carriers in the active layer region, increase the AlAs mixed crystal ratio at both interfaces of the active layer (indicated by A and B in FIG. 3). It is necessary to form a clad layer having a bandgap of a certain value or more on both sides of the active layer. However, if the AlAs mixed crystal ratio is too high, Al oxidation is promoted, which is a disadvantageous condition for the moisture resistance of the cladding layer.

Therefore, the above-mentioned GaAs substrate removal type Ga
Although the AlAs semiconductor light-emitting device is protected by the die-bonding adhesive and the mold resin after being assembled, it may absorb a little moisture depending on the type of the die-bonding adhesive and the mold resin under a use condition where the environment changes drastically such as outdoors. There is a problem that will happen. Therefore, it is necessary to set the optimum value of the AlAs mixed crystal ratio of the clad layer in consideration of the balance between humidity resistance and high output.

Further, when a GaAlAs semiconductor light emitting device is formed by the liquid phase epitaxial slow cooling method as described above, Al which is taken in as a solid phase may be formed depending on the growth raw material charge amount and the growth conditions such as the epitaxial temperature.
A segregation phenomenon occurs in which the ratio of As (AlAs mixed crystal ratio) decreases toward the growth direction. Therefore, as shown in FIG.
The AlAs mixed crystal ratio of the GaAs first cladding layer is GaAs
High at the interface C of the substrate-GaAlAs first cladding layer,
It becomes lower at the interface A of the AlAs first cladding layer-active layer.
Therefore, when the AlAs mixed crystal ratio of the GaAlAs first clad layer growth start surface C, which becomes the contact surface with the die bonding adhesive after removing the GaAs substrate, is restricted,
There is also a problem that the AlAs mixed crystal ratio at the interface A of the active layer, which is the growth end surface of the AlAs first cladding layer, may be further lowered, and a sufficient carrier confinement effect may not be obtained.

Therefore, the object of the present invention is to provide a high moisture-proof GaAl which has a sufficient carrier confinement effect even if there are restrictions on the AlAs mixed crystal ratio on both the front and back surfaces of the device.
An object of the present invention is to provide a method for manufacturing a GaAlAs semiconductor light emitting device capable of manufacturing an As semiconductor light emitting device.

[0007]

In order to achieve the above object, the present invention is a GaAlAs semiconductor light emitting device in which a GaAlAs first cladding layer is formed on a GaAs substrate, and an active layer and a GaAlAs second cladding layer are sequentially formed. In the method of manufacturing, the growth melt for growing the GaAlAs first cladding layer is divided into upper and lower two layers when the GaAlAs first cladding layer is formed, and a lower layer of the divided growth melt is grown. The melt is brought into contact with the surface of the GaAs substrate and the melt back of the GaAs substrate is used to
A first GaAlAs first clad layer having a low As mixed crystal ratio is grown, and subsequently, the division of the growth melt is released to remove the first
Is characterized in that a second GaAlAs first clad layer exhibiting an AlAs mixed crystal ratio higher than that of the GaAlAs first clad layer is grown.

[0008]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is an explanatory diagram related to a method of manufacturing a GaAlAs semiconductor light emitting device in this embodiment. FIG. 2 shows a cross-sectional view of a GaAlAs semiconductor light emitting device formed by the method for manufacturing a GaAlAs semiconductor light emitting device according to this embodiment and the AlAs mixed crystal ratio of each layer. Hereinafter, FIG. 1 and FIG.
A method of manufacturing the GaAsAs semiconductor light emitting device in this embodiment will be described below.

First, as shown in FIG. 1 (a), the melt reservoir 1
Material in each tank (Ga, GaAs polycrystal, Al, dopant, etc.)
The epitaxial boat containing is heated to 900 ° C. to 1000 ° C. in a hydrogen atmosphere and held for a certain period of time until the materials in the respective tanks are melted to form a growth melt having a uniform liquid composition. In addition, 3 is a base of the above-mentioned epitaxial boat.

Next, as shown in FIG. 1 (b), the operating rod 11
Is operated to separate the growth melt 5 in the first tank 1a into the growth melt 8 and the growth melt 9 by the partition plate 4. After that, Fig. 1 (c)
As shown in FIG. 1, the operating rod 12 is operated to move the slider 2, and the GaAs substrate 13 mounted on the slider 2 is moved to the first position.
The growth melt 9 in the tank 1a is brought into contact, and the atmospheric temperature is raised by Δt ° C.

Then, the GaAs substrate 13 is melted back in an amount obtained from the temperature difference (Δt ° C.) and the absolute amount of the growth melt 9, and the growth melt 9 is A
The liquid composition is such that the lAs mixed crystal ratio is low. Here, in order to reduce the meltback amount in the growth melt 9, the amount of the growth melt 9 needs to be sufficiently smaller than the amount of the growth melt 8.

Subsequently, the temperature is lowered in the above-mentioned state, and epitaxial growth is performed to form the first GaAlAs first clad layer 14 which is the first GaAlAs first clad layer 14. As shown in FIG. 2, the GaAlAs first clad a layer 14 has a low AlAs mixed crystal ratio and serves as a protective layer for the purpose of moisture resistance. Therefore, it is sufficient to have a film thickness of several μm.

Thereafter, as shown in FIG. 1 (d), the operating rod 11 is operated to pull out the partition plate 4 from the first tank 1a. Then, the growth melt 10 (mixed melt of the growth melt 8 and the growth melt 9) is coated on the GaAs substrate 13 after the growth of the above-described GaAsAlAs first clad a layer 14, and the temperature is lowered. 2 GaAlAs first cladding layer, which is GaAlAs first
The clad b layer 15 is formed. At that time, since the amount of the growth melt 9 is sufficiently smaller than the amount of the growth melt 8 as described above, even if the partition plate 4 is removed from the first tank 1a, the growth melt 10 and the growth melt The liquid composition between No. 8 and 8 is almost unchanged. Therefore, the GaAlAs first clad b layer 15
There is little influence of the growth melt 9 when forming

Thereafter, as in the case of the conventional epitaxial growth, the operating rod 12 is operated to move the slider 2 to move the GaAl.
As first clad a layer 14 and GaAlAs first clad b
The GaAs substrate 13 on which the layer 15 is formed is sequentially brought into contact with the growth melt 6 and the growth melt 7, and the temperature is also lowered, thereby sequentially growing the active layer 16 and the GaAsAs second cladding 17.

Thus, as shown in FIG. 2 (A), GaAs
On the substrate 13, a GaAlAs first clad a layer 14, GaAlA
A double heterostructure GaAlAs semiconductor light emitting device in which the s first clad b layer 15, the active layer 16, and the GaAlAs second clad layer 17 are successively and successively grown by liquid phase epitaxial growth is obtained. After that, as shown in FIG. 2 (B), GaAlAs
Back surface of semiconductor light emitting device (GaAlAs first cladding a
The GaAs substrate 13 is removed so that light can be extracted also from the growth initiation surface C) of the layer 14.

The GaAs substrate removal type double hetero GaAs semiconductor light emitting device formed as described above is shown in FIG.
As shown in (B), the outermost GaAlAs first cladding a
Since the AlAs mixed crystal ratio of the layer growth start surface C is low, Al oxidation is not promoted, moisture resistance can be improved, and high reliability can be achieved.

The GaAlAs first clad b layer 15 formed on the GaAs substrate 13 side of the active layer 16 for effectively confining carriers in the active layer 16 is a GaAlAs first layer.
Since it is formed inside the clad a layer 14, the AlAs mixed crystal ratio of the growth start surface is not particularly limited. Therefore, if the AlAs mixed crystal ratio on the growth initiation surface of the GaAlAs first clad b layer is sufficiently high, the AlAs mixed crystal ratio at the active layer interface A can be kept high even if the segregation phenomenon occurs. That is, the GaAsAs first clad a which becomes the contact surface with the die bonding adhesive after the GaAs substrate 13 is removed.
Even if the AlAs mixed crystal ratio of the layer growth start surface C is limited, Ga
The AlAs first clad b layer 15 has a bandgap of a certain level or more, so that carriers can be sufficiently confined in the region of the active layer 16, and a high output can be obtained.

The conventional GaAs substrate removal type GaAs
In the case of an As semiconductor light-emitting device, if there is a restriction on the AlAs mixed crystal ratio on both the front and back sides, a GaAl
As the first cladding layer is formed, the active layer interface A is inevitably formed.
The AlAs mixed crystal ratio is substantially determined by the segregation phenomenon. However, according to this embodiment, two GaAlAs first clad layers having different compositions can be formed on the GaAs substrate by the growth melt of one composition.
Substrate removal type GaAs AlAs on both front and back surfaces of semiconductor light emitting device
Even if the s mixed crystal ratio is restricted, the AlAs mixed crystal ratio at the active layer interface A can be increased. Therefore, the degree of freedom in the element design is expanded accordingly.

The specific construction of the epitaxial boat for carrying out the present invention is not limited to the construction of the epitaxial boat in the above-mentioned embodiment. In short,
It is only necessary that the first tank 1a has a structure in which it is temporarily divided into upper and lower parts.

[0020]

As is apparent from the above, the method of manufacturing a GaAlAs semiconductor light emitting device according to the present invention is characterized in that when the GaAlAs first cladding layer is formed on the GaAs substrate, the Ga
The growth melt for growing the AlAs first clad layer is divided into upper and lower layers, and the growth melt of the lower layer is brought into contact with the surface of the GaAs substrate, and the melt back of the GaAs substrate is used to make Al.
After growing the first GaAlAs first clad layer having a low As mixed crystal ratio, the division of the growth melt is released to exhibit a higher AlAs mixed crystal ratio than the first GaAlAs first clad layer. The second GaAlAs first clad layer is grown, and the active layer and the GaAlAs second clad layer are sequentially grown. Therefore, the GaAlAs first clad layer in the obtained GaAlAs semiconductor light emitting device is in contact with the GaAs substrate. The first Ga having a low AlAs mixed crystal ratio
AlAs a high Al in contact with the first cladding layer and the active layer
It is composed of two layers, that is, the second GaAlAs first cladding layer having an As mixed crystal ratio.

Therefore, according to the present invention, even if the GaAs substrate is removed to extract light from both the front and back surfaces of the device, the first GaAsAlAs first cladding layer side, which has a low AlAs mixed crystallinity, is the outermost side, which is excellent. Further, it is possible to manufacture a highly reliable GaAsAs semiconductor light emitting device exhibiting moisture resistance.

Further, according to the present invention, since the AlAs mixed crystal ratio of the second GaAlAs first cladding layer in contact with the active layer is high, there is a restriction of the AlAs mixed crystal ratio on the growth starting surface of the GaAs substrate. Even if the second GaAlAs first clad layer has a bandgap of a certain level or more, carriers can be sufficiently confined in the active layer region.
An As semiconductor light emitting device can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing an operation of an epitaxial boat in the method of manufacturing a GaAsAs semiconductor light emitting device of the present invention.

FIG. 2 is a cross-sectional view of a GaAlAs semiconductor light emitting device formed by the method for manufacturing a GaAlAs semiconductor light emitting device according to the present invention and a diagram showing AlAs mixed crystal ratios of respective layers.

FIG. 3 is a cross-sectional view of a GaAlAs semiconductor light emitting device formed by a conventional method for manufacturing a GaAlAs semiconductor light emitting device and a diagram showing AlAs mixed crystal ratios of respective layers.

[Explanation of symbols]

1 ... Melt reservoir, 2 ... Slider,
4 ... Partition board, 5, 6, 7, 8,
9, 10 ... Growth melt, 11, 12 ... Operation rod,
13 ... GaAs substrate, 14 ... GaAlAs first clad a layer, 15 ... GaAlAs first clad b layer, 16 ... Active layer, 17 ... GaAlAs second clad layer.

Claims (1)

[Claims] 1. A method of manufacturing a GaAlAs semiconductor light-emitting device, comprising: forming a GaAlAs first clad layer on a GaAs substrate; and sequentially forming an active layer and a GaAlAs second clad layer, wherein the GaAlAs first clad layer is formed. , The growth melt for growing the first GaAlAs clad layer is divided into upper and lower layers, and the lower growth melt of the divided growth melt is GaAs.
The first GaAlAs first clad layer having a low AlAs mixed crystal ratio is grown by contacting with the substrate surface and utilizing the melt back of the GaAs substrate. 1 G
aAlAs AlA higher than the AlAs mixed crystal ratio of the first cladding layer
A method of manufacturing a GaAlAs semiconductor light-emitting device, which comprises growing a second GaAlAs first cladding layer exhibiting an s mixed crystal ratio.