JP2001077480A - Gallium nitride compound semiconductor light-emitting element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gallium nitride compound semiconductor light emitting element and its manufacturing method by which the influence on a transition active layer caused from distortion can be reduce, diffusion of magnesium as a P-type impurity Mg into the active layer by means of transition to be reduced, and the light emission efficiency and reliability be improved. SOLUTION: This gallium nitride compound semiconductor light-emitting element contains indium and aluminum, and at least a pair of clad layers 4 and 8, a quantum-well structure active layer 6, and a cooling layer 5 and a heating layer 7, including a GaN thin layer between at least either of the clad layer, and the quantum-well structure active layer are laminated on a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gallium nitride-based compound semiconductor light emitting device capable of emitting light in the blue to ultraviolet region and a method of manufacturing the same, and more particularly, to a gallium nitride-based compound semiconductor light emitting device having excellent luminous efficiency and reliability. About.

[0002]

2. Description of the Related Art FIG. 11 shows a typical conventional nitride semiconductor laser device. This semiconductor laser device includes a GaN buffer layer 101, a SiO ₂
Layer 102, n-type GaN layer 103, n-type In _0.1 Ga _0.9 N
Layer 104, n-type _{Al 0.14 Ga 0. 86 N / GaN} · MD-S
LS (modulation doping superlattice) layer 105, n-type GaN layer 106, In _0.02 Ga _0.98 N / In _0.15 Ga _0.85 N quantum well structure active layer 107, p-type Al _0.2 Ga _0.8 N layer 10
8, p-type GaN layer 109, p-type Al _0.14 Ga _0.86 N / G
The aN · MD-SLS layer 110 and the p-type GaN contact layer 111 are sequentially grown, and the p-type electrode 112 and the n-type electrode 1
13. A nitride-based semiconductor laser device having the insulator film 114 formed thereon is manufactured.

[0003]

SUMMARY OF THE INVENTION An n-type AlGaN laminated below the InGaN multiple quantum well active layer 107
/ GaN-MD-SLS layer 105 causes n
The dislocations generated in the AlGaN / GaN MD-SLS layer 105 become threading dislocations into the InGaN multiple quantum well active layer 107, deteriorating the crystallinity of the active layer 107 and causing the active layer to have a significantly reduced luminous efficiency. In addition, there is a problem that the reliability of the light emitting element is deteriorated.

Further, in the p-type AlGaN / GaN MD-SLS layer 110 on the InGaN multiple quantum well active layer 107, the p-type AlGaN / GaN
The dislocation generated in the D-SLS layer 110 is caused by the InGaN
Dislocations are transferred to the multiple quantum well active layer 107, and p-type AlGaN / GaN MD is transferred to the active layer 107 via the dislocations.
The diffusion of Mg, which is a P-type impurity contained in the SLS layer 110 and the p-type GaN contact layer 111, deteriorates the crystallinity of the active layer, significantly lowers the luminous efficiency of the active layer, and reduces the There has been a problem of deteriorating reliability.

[0005]

The gallium nitride based compound semiconductor light emitting device of the present invention has a pair of clad layers and a quantum well active layer on a substrate, and comprises a gallium nitride based compound semiconductor light emitting device containing indium and aluminum. It has a stacked structure formed between at least one cladding layer and the quantum well active layer at a temperature lower than the growth temperature of the cladding layer and higher than the growth temperature of the quantum well active layer.

The gallium nitride based compound semiconductor light emitting device of the present invention is characterized in that the laminated structure includes a GaN layer.

The gallium nitride-based compound semiconductor light emitting device of the present invention is characterized in that at least one layer of AlGaN
And a GaN layer.

The gallium nitride based compound semiconductor light emitting device of the present invention is characterized in that the laminated structure has a three-layer structure including a GaN layer sandwiched between a pair of AlGaN layers.

The gallium nitride based compound semiconductor light emitting device of the present invention is characterized in that the laminated structure is formed on both sides of an active layer.

[0010] The method of manufacturing a gallium nitride-based compound semiconductor light-emitting device of the present invention forms a step of forming a Al _X Ga _1-X N cladding layer on a substrate, a quantum well active layer at a lower temperature than the cladding layer Forming a stacked structure between at least one of the cladding layers and the quantum well active layer at a temperature lower than the cladding layer and at a temperature higher than the quantum well active layer. It is characterized by doing.

[0011] The method of manufacturing a gallium nitride-based compound semiconductor light-emitting device of the present invention includes the steps of forming a Al _X Ga _1-X N cladding layer on a substrate, forming a laminated structure by lowering the substrate temperature, further The method is characterized by including a step of forming a quantum well active layer by lowering the substrate temperature, a step of forming a stacked structure by raising the substrate temperature again, and a step of forming a cladding layer by further raising the substrate temperature.

In the method of manufacturing a gallium nitride-based compound semiconductor light emitting device according to the present invention, the formation temperature of the laminated structure is changed intermittently or stepwise between a cladding layer formation temperature and a quantum well active layer formation temperature. Features.

The present invention for solving the problem will be described with reference to FIG. After growing a layer containing n-type AlGaN located below the InGaN-based active layer (here, the n-type AlGaN cladding layer 4 is shown), the substrate temperature must be lowered in order to grow the active layer. . Here, the growth temperature of the n-type cladding layer is 1100 ° C., and the growth temperature of the active layer is 750 ° C. In the present invention, in order to suppress the dislocation generated in the n-type cladding layer from propagating to the active layer during the cooling down to the growth of the active layer, the n-type AlGaN as the n-type cooling layer 5 is formed on the n-type AlGaN cladding layer 4. Layer 51, n
Type GaN layer 52 and an n-type AlGaN layer 53 are sequentially stacked,
The n-type GaN layer 52 grows when the substrate temperature is between 1050 ° C. and 850 ° C. By growing at a substrate temperature between 1050 ° C. and 850 ° C., the n-type GaN layer 52 is laminated while maintaining good crystallinity. The dislocations generated in the n-type AlGaN cladding layer 4 due to the strain are absorbed by the n-type GaN layer 52, so that the density of threading dislocations into the InGaN multiple quantum well active layer 6 decreases.

Next, after growing the active layer, the substrate temperature must be raised. After growing the InGaN multiple quantum well active layer, the p-type A
During the heating up to the growth of the layer containing lGaN (here, the p-type AlGaN cladding layer 8 is shown), the InGa
On the N multiple quantum well active layer 6, a p-type AlGaN layer 71, a p-type GaN layer 72,
A p-type AlGaN layer 73 is sequentially stacked, and a p-type GaN layer 72 is formed.
Grows at a substrate temperature of 850C to 1050C.
By growing at a substrate temperature between 850 ° C. and 1050 ° C., the p-type GaN layer 72 is stacked while maintaining good crystallinity. As a result, dislocations generated in the p-type AlGaN cladding layer 8 due to the strain are absorbed by the p-type GaN layer 72, and the dislocation density to the InGaN multiple quantum well active layer 6 is reduced. Of the p-type cladding layer 8 to the active layer 6 and the p-type
The diffusion of Mg, which is a type impurity, is reduced, and the deterioration of the crystallinity of the active layer 6 is suppressed.

Thus, a gallium nitride-based compound semiconductor light-emitting device having high luminous efficiency and excellent reliability can be obtained.

Here, the n-type GaN layer 52 during the temperature drop is
The layer thickness of the p-type GaN layer 72 during the temperature rise is from 10 nm to 10 nm.
0 nm, preferably in the range of 50 nm to 80 nm. If the layer thickness is less than 10 nm, the dislocations of the AlGaN layer penetrate, and if it is more than 100 nm, the efficiency of confining light from the active layer is reduced and the light emission efficiency is reduced. .

Here, the n-type AlGaN layer 51 and the n-type AlGaN
The relationship of the Al composition ratio of the GaN layer 53 is that if the In composition ratio of the InGaN-based multiple quantum well layer 6 is large, the n-type AlGaN
The Al composition ratio of the layer 51 may be smaller than that of the n-type AlGaN layer 53,
When the n composition ratio is set to be small, the energy gap difference between the cladding layers 4 and 8 becomes small, so that the Al composition ratio of the n-type AlGaN layer 51 becomes n-type AlGaN layer 53.
By setting it larger, the n-type AlGaN layer 51
Functions as a barrier layer for holes injected into the active layer. Here, the n-type AlGaN layer 53 and the p-type AlGaN layer 71 are grown at a substrate temperature of 750 ° C. to 950 ° C. However, since the thickness of each layer is small, the crystallinity of the stacked layers is There is no particular problem.

Here, the cooling layer 5 or the heating layer 7 may be grown while cooling or raising the temperature, or may be grown at a certain temperature between the growth temperature of the active layer and the growth temperature of the cladding layer. I don't care. Also, an AlGaN layer in contact with the cladding layer in the temperature-lowering layer and the temperature-raising layer, that is, n-type AlGaN
The layer 51 and the p-type AlGaN layer 73 may be included in the cladding layer without being clearly distinguished from the cladding layer. At this time, it is necessary to change the growth temperature in the cladding layer so as to be similar to the growth temperature of the n-type AlGaN layer 51 and the p-type AlGaN layer 73.

The AlGaN layers in contact with the active layer in the temperature-lowering layer and the temperature-raising layer, that is, the n-type AlGaN layer 53 and the p-type AlGaN layer 71 are formed of the well layer of the InGaN single or multiple quantum well of the active layer. When the In composition ratio is larger than 0.2, the Eg of the cladding layers 4 and 8
Can be omitted because it is not necessary to particularly form it.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. In the following embodiments, the semiconductor laser device of the present invention will be described, but it goes without saying that the present invention can be applied to a light emitting diode. Here, the gallium nitride-based compound semiconductor described below _{In s Al t Ga 1-st} N (0 ≦
s, 0 ≦ t, s + t ≦ 1).

Example 1 FIG. 1 is a schematic sectional view of a semiconductor laser according to a first embodiment of the present invention. This semiconductor laser device has a GaN buffer layer 2, an n-type GaN contact layer 3, an n-type AlGaN
Cladding layer 4, n-type cooling layer (n-type AlGaN layer 51, n-type
-Type GaN layer 52, n-type AlGaN layer 53) 5, InGa
An N-single quantum well active layer 6, a p-type AlGaN cladding layer 8, and a p-type GaN contact layer 9 are sequentially provided. 10 is a p-type electrode and 11 is an n-type electrode. The semiconductor laser device according to the present invention includes an n-type cooling layer 5, that is, an n-type AlGaN layer 51;
The n-type GaN layer 52 and the n-type AlGaN layer 53 are n-type AlG
It is characterized in that it is laminated between the aN cladding layer 4 and the InGaN single quantum well active layer 6.

Next, the manufacturing process of this semiconductor laser is shown in FIG.
This will be described based on FIG. The gallium nitride semiconductor laser metal organic vapor phase growth method for the preparation of (hereinafter MOCVD method) using trimethyl gallium as ammonia NH _3, III group material sapphire substrate, as a group V raw material as a substrate (TMG), trimethyl aluminum ( TMA), trimethylindium (TMIn), biscyclopentadienyl magnesium (CP ₂ Mg) as a p-type impurity,
Monosilane (SiH ₄ ) is used as an n-type impurity, and H ₂ and N ₂ are used as carrier gases.

First, the sapphire substrate 1 is introduced on a susceptor of the MOCVD apparatus. The substrate temperature is raised to 1200 ° C., and the surface of the substrate is cleaned in an atmosphere of H ₂ and N ₂ . Next, a GaN buffer layer 2 (50 nm thick) is laminated on the sapphire substrate 1 at a substrate temperature of 540 ° C. N-type GaN contact layer 3 (4 μm thickness) at a substrate temperature of 1050 ° C., n-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
The N cladding layer 4 (thickness 0.15 μm) is laminated (FIG.
(A)).

Next, the substrate temperature is increased from 1100 ° C. to 750 ° C.
While the temperature is lowered to n, the n-type Al _0.1 Ga _0.9 N clad layer 4
An n-type Al _0.15 Ga _0.85 N layer 51 (thickness: 50 nm) is formed thereon,
n-type GaN layer 52 (80 nm thick), n-type Al _0.12 Ga
_0.88 N layer 53 (50 nm thick) is laminated (FIG. 4
(B)).

Here, the n-type Al _0.15 Ga _0.85 N layer 51 has a substrate temperature between 1100 ° C. and 1050 ° C., the n-type GaN layer 52 has a substrate temperature between 1050 ° C. and 850 ° C.
_The substrate temperature of the _0.12 Ga _0.88 N layer 53 is 850 ° C. to 750 ° C.
It is preferred to grow between.

Next, at a substrate temperature of 750.degree._0.01Ga
_0.99An N quantum well active layer (thickness: 3 nm) 6 is laminated (FIG.
4 (c)). Next, the substrate temperature is raised to 1100 ° C. and the p-type
Al _0.1Ga_0.9N cladding layer 8 (0.15 μm thickness),
At a substrate temperature of 1050 ° C., the p-type GaN contact layer 9 (thickness:
(Thickness: 0.3 μm).

Next, the wafer is taken out of the MOCVD apparatus, a resist mask for dry etching is formed on the p-type GaN contact layer 9, and the surface of the n-type GaN contact layer 3 is exposed by dry etching (FIG. 4).
(D) 12).

Next, an n-type electrode 11 is formed on the exposed surface 12 of the n-type GaN contact layer 3 and a p-type electrode 10 is formed on the surface of the p-type GaN contact layer 9. Finally 350μ width
The semiconductor laser device is divided into chips having a length of 600 μm and a length of 600 μm by scribing or the like (FIG. 4E).

FIG. 5 shows the relationship between the growth temperature and the stacked body.

At a substrate temperature of 1050 ° C., an n-type GaN contour
Layer 3, n-type Al at a substrate temperature of 1100 ° C._0.1Ga_0.9
The N clad layer 4 is laminated, and the substrate temperature is reduced from 1100 ° C. to 75
While cooling to 0 ° C., an n-type cooling layer 5 is formed on the cladding layer 4.
Are laminated. More specifically, as the n-type cooling layer 5, the substrate temperature
N-type Al between 1100 ° C and 1050 ° C_0.15Ga
_0.85N layer 51, when substrate temperature is between 1050 ° C and 850 ° C
n-type GaN layer 52, substrate temperature between 850 ° C. and 750 ° C.
N-type Al_0.12Ga_0.88The N layer 53 is laminated. Next
At a substrate temperature of 750 ° C._0.01Ga_0.99N quantum well active
Layer (thickness: 3 nm) 6, p-type A at substrate temperature of 1100 ° C
l_0.1Ga_0.9N clad layer 8 at substrate temperature of 1050 ° C
A p-type GaN contact layer 9 is sequentially stacked.

According to the device structure of the present invention, n-type AlGa
On the N cladding layer 4, an n-type AlGa
An N layer 51, an n-type GaN layer 52, and an n-type AlGaN layer 53 are sequentially stacked, and the n-type GaN layer 52 has a substrate temperature of 1050.
It grows between 850C and 850C. Substrate temperature 1050 ° C ~
The n-type GaN layer 52 is grown at a temperature between 850 ° C.
Are laminated while maintaining good crystallinity. The dislocation generated in the n-type AlGaN cladding layer 4 due to the strain is n-type GaN
Absorbed in the layer 52, the density of threading dislocations into the active layer decreases.

When the In composition ratio of the InGaN multiple quantum well layer 6 is set to be small, the cladding layers 4 and 8
N-type Al
By setting the Al composition ratio of the GaN layer 51 to be higher than that of the n-type AlGaN layer 53, the n-type AlGaN layer 51 also has a function as a barrier layer for holes injected into the active layer. From the above phenomenon, the n-type AlGaN layer 51 is particularly effective when the In composition ratio of the multiple or single InGaN quantum structure active layer 6 is in the range of 0.2 or less. For this reason, a light emitting element in the ultraviolet region with excellent luminous efficiency and reliability can be provided.

The nitride-based semiconductor laser manufactured in this embodiment has a long life of 2000 hours at an ambient temperature of 60 ° C. and an optical output of 3 mW, and has improved reliability.

The method of manufacturing a semiconductor light emitting device according to the present invention may further comprise a step of laminating at least a clad layer on a semiconductor substrate, a step of laminating the temperature-lowering layer while lowering the substrate temperature, a single or multiple quantum well active layer. And the above object is achieved.

(Embodiment 2) FIG. 2 is a schematic sectional view of a semiconductor laser according to a second embodiment of the present invention. This semiconductor laser device has a GaN substrate on a sapphire substrate 1.
Buffer layer 2, n-type GaN contact layer 3, n-type AlG
aN cladding layer 4, InGaN single quantum well active layer 6
And a p-type temperature raising layer (p-type AlGaN layer 71, p-type GaN layer 72, p-type AlGaN layer 73) 7, a p-type AlGaN cladding layer 8, and a p-type GaN contact layer 9 in this order. 10 is a p-type electrode and 11 is an n-type electrode. According to the semiconductor laser device of the present invention, the p-type heating layer (P-type AlGaN layer 7)
1, p-type GaN layer 72, p-type AlGaN layer 73) 7
It is characterized in that it is stacked between the AlGaN cladding layer 8 and the InGaN single quantum well active layer 6.

Next, the manufacturing process of this semiconductor laser is shown in FIG.
This will be described based on FIG.

For manufacturing a gallium nitride based semiconductor laser, M
Sapphire substrate, group V raw material, III using OCVD method
The group material, p-type impurity, n-type impurity and carrier gas were the same as in the first embodiment.

First, the sapphire substrate 1 is introduced onto a susceptor of the MOCVD apparatus. The substrate temperature is raised to 1200 ° C., and the surface of the substrate is cleaned in an atmosphere of H ₂ and N ₂ . Next, a GaN buffer layer 2 (thickness: 50 nm) is laminated on the sapphire substrate 1 at a substrate temperature of 550 ° C. N-type GaN contact layer 3 (4 μm thickness) at a substrate temperature of 1050 ° C., n-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
An N clad layer 4 (0.1 μm thick) is laminated (FIG. 6).
(A)).

Next, at a substrate temperature of 770 ° C., In_0.3Ga
_0.7An N quantum well active layer (thickness: 3 nm) 6 is laminated. Next
Meanwhile, while raising the substrate temperature from 770 ° C. to 1100 ° C.
In _0.3Ga_0.7On the N quantum well active layer (thickness: 3 nm) 6
P-type Al_0.05Ga_0.95N layer 71 (20 nm thick), p
GaN layer 72 (50 nm thick), p-type Al_0.12Ga_0.
88An N layer 73 (thickness: 30 nm) is laminated.

Here, p-type Al_0.05Ga_0.95N layer 71
When the substrate temperature is between 770 ° C. and 950 ° C., the p-type GaN layer 72
Is a substrate temperature between 950 ° C. and 1050 ° C., p-type Al_0.12
Ga _0.88The substrate temperature of the N layer 73 is 1050 ° C. to 1100 ° C.
It is preferable that the growth be carried out during this period (FIG. 6B).

Next, at a substrate temperature of 1100.degree.
_0.1 Ga _0.9 N clad layer 8 (0.1 μm thick), p-type GaN contact layer 9 (0.1 mm thick) at a substrate temperature of 1050 ° C.
3 μm) are sequentially laminated (FIG. 6C).

Next, the wafer is taken out of the MOCVD apparatus, a resist mask is formed as a dry etching mask on the p-type GaN contact layer 9, and the surface of the n-type GaN contact layer 3 is exposed by dry etching (FIG. 6 ( d) 12).

Next, an n-type electrode 11 is formed on the exposed surface of the n-type GaN contact layer 3, and a p-type electrode 10 is formed on the surface of the p-type GaN contact layer 9.

Finally, a semiconductor laser device is manufactured by dividing into chips of 350 μm in width and 600 μm in length by scribing or the like (FIG. 6E).

FIG. 7 shows the relationship between the growth temperature and the laminated body. N-type GaN contact layer 3 at a substrate temperature of 1050 ° C., n-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
An N clad layer 4 is laminated, and then the substrate is heated at a substrate temperature of 770 ° C.
An n _0.3 Ga _0.7 N quantum well active layer (thickness: 3 nm) 6 is laminated, and a substrate temperature of 770 ° C.
While the temperature is raised to 100 ° C., the p-type temperature raising layer 7 is laminated. More specifically, the substrate temperature is 770 ° C. to 95
The p-type Al _0.05 Ga _0.95 N layer 71 during 0 ° C., the p-type GaN layer 72 between 950 ° C. and 1050 ° C., and the p-type Al _0.12 Ga between 1050 ° C. and 1100 ° C.
_0.88 N layer 73 is laminated.

Next, at a substrate temperature of 1100.degree.
_0.1 Ga _0.9 N clad layer 8, p at substrate temperature 1050 ° C
Type GaN contact layers 9 are sequentially stacked.

According to the device structure of the present invention, the InGa
On the N multiple quantum well active layer 6, a p-type AlGaN layer 71, a p-type GaN layer 72, a p-type AlGaN
The layers 73 are sequentially stacked, and the p-type GaN layer 72 grows at a substrate temperature of 950 ° C. to 1050 ° C. Substrate temperature is 95
By growing between 0 ° C. and 1050 ° C., p-type Ga
The N layer 72 is laminated while maintaining good crystallinity. The dislocation generated in the p-type AlGaN cladding layer 8 due to the strain is p
Is absorbed by the p-type GaN layer 72 and the threading dislocation density into the InGaN multiple quantum well active layer 6 is reduced. Therefore, the diffusion of Mg, which is a p-type impurity, through the threading dislocation is reduced. Deterioration of crystallinity can be suppressed. Therefore, a light-emitting element having excellent luminous efficiency and reliability can be obtained.

The semiconductor laser fabricated in this embodiment has a long life of 3000 hours at an ambient temperature of 60 ° C. and an optical output of 3 mW, and has improved reliability.

Further, the method for manufacturing a semiconductor light emitting device of the present invention includes a step of laminating at least a clad layer on a semiconductor substrate, a step of laminating a single or multiple quantum well active layer, and the step of increasing the substrate temperature while increasing the temperature. The above object is achieved by including a step of laminating a thermal layer.

(Embodiment 3) FIG. 3 is a schematic sectional view of a semiconductor laser according to a third embodiment of the present invention. This semiconductor laser device has a GaN substrate on a sapphire substrate 1.
Buffer layer 2, n-type GaN contact layer 3, n-type AlG
aN cladding layer 4, n-type cooling layer (n-type AlGaN layer 5)
1, n-type GaN layer 52, n-type AlGaN layer 53) 5, I
An nGaN multiple quantum well active layer 6 and a p-type temperature raising layer (p-type A
An lGaN layer 71, a p-type GaN layer 72, a p-type AlGaN layer 73) 7, a p-type AlGaN cladding layer 8, and a p-type GaN contact layer 9 are sequentially provided. 10 is a P-type electrode, 11
Is an N-type electrode.

The semiconductor laser device of the present invention comprises an n-type cooling layer 5, ie, an n-type AlGaN layer 51, an n-type GaN layer 52,
Type AlGaN layer 53 is formed of n-type AlGaN cladding layer 4 and
Between the nGaN multiple quantum well active layers 6 and the p-type temperature raising layer (p-type AlGaN layer 71, p-type GaN layer 72, p-type AlGaN
The layers 73) and 7 are composed of the p-type AlGaN cladding layer 8 and the InGaN
It is characterized in that it is stacked between the multiple quantum well active layers 6.

Next, the manufacturing process of this semiconductor laser is shown in FIG.
This will be described based on FIG. The MOCVD method was used to fabricate a gallium nitride based semiconductor laser, and a sapphire substrate, a group V material,
Group II raw materials, p-type impurities, N-type impurities, and carrier gas were the same as in the first embodiment.

First, the sapphire substrate 1 is introduced on a susceptor of the MOCVD apparatus. The substrate temperature is raised to 1200 ° C., and the surface of the substrate is cleaned in an atmosphere of H ₂ and N ₂ . Next, a GaN buffer layer 2 (50 nm thick) is laminated on the sapphire substrate 1 at a substrate temperature of 540 ° C. N-type GaN contact layer 3 (4 μm thick) at a substrate temperature of 1050 ° C., N-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
An N clad layer 4 (0.15 μm thick) is laminated (FIG. 8).
(A)).

Next, the n-type Al _0.1 Ga _0.9 N cladding layer 4
While the substrate temperature is lowered from 1100 ° C. to 750 ° C., an n-type Al _0.15 Ga _0.85 N layer 51 (thickness: 50 nm)
-Type GaN layer 52 (80 nm thick), n-type Al _0.12 Ga
_0.88 N layer 53 (thickness: 50 nm) is laminated (FIG. 8)
(B)).

Here, the n-type Al _0.15 Ga _0.85 N layer 51 has a substrate temperature between 1100 ° C. and 1050 ° C., the n-type GaN layer 52 has a substrate temperature between 1050 ° C. and 850 ° C.
_The substrate temperature of the _0.12 Ga _0.88 N layer 53 is 850 ° C. to 750 ° C.
It is preferred to grow between.

Here, the n-type Al _0.15 Ga _0.85 N layer 51 has a substrate temperature between 1100 ° C. and 1030 ° C., the n-type GaN layer 52 has a substrate temperature between 1030 ° C. and 950 ° C.
_The substrate temperature of the _0.12 Ga _0.88 N layer 53 is 950 ° C. to 790 ° C.
It is preferred to grow between. Next, a substrate temperature of 790 ° C.
The In _0.15 Ga _0.85 N quantum well layer (thickness 4 nm) was
A quantum structure active layer 6 composed of two layers, an In _0.02 Ga _0.98 N barrier layer (8 nm thick), is laminated.

Next, the substrate temperature was raised from 770 ° C. to 1100 on the In _0.3 Ga _0.7 N quantum well active layer (thickness: 3 nm).
While raising the temperature to ° C., the p-type Al _0.05 Ga _0.95 N layer 71 (thickness 20 nm), the p-type GaN layer 72 (thickness 50 nm),
A type Al _0.12 Ga _0.88 N layer 73 (thickness: 30 nm) is laminated.

Here, p-type Al_0.05Ga_0.95N layer 71
When the substrate temperature is between 770 ° C. and 950 ° C., the p-type GaN layer 72
Is a substrate temperature between 950 ° C. and 1050 ° C., p-type Al_0.12
Ga _0.88The substrate temperature of the N layer 73 is 1050 ° C. to 1100 ° C.
It is preferable to grow during (FIG. 8C).

Next, at a substrate temperature of 1100 ° C., the p-type Al
_0.1 Ga _0.9 N clad layer 8 (0.1 μm thick), p-type GaN contact layer 9 (0.1 mm thick) at a substrate temperature of 1050 ° C.
3 μm).

Next, at a substrate temperature of 1100 ° C., the p-type Al
_0.1 Ga _0.9 N clad layer 8 (0.1 μm thick), p-type GaN contact layer 9 (0.1 mm thick) at a substrate temperature of 1030 ° C.
3 μm).

Next, the wafer is taken out of the MOCVD apparatus, a resist mask is formed as a dry etching mask on the p-type GaN contact layer 9, and the surface of the n-type GaN contact layer 3 is exposed by dry etching (FIG. 8 ( d) 12).

Next, an n-type electrode 11 is formed on the exposed surface of the n-type GaN contact layer 3, and a p-type electrode 10 is formed on the surface of the p-type GaN contact layer 9. Finally, a semiconductor laser device is manufactured by dividing into chips of 350 μm in width and 600 μm in length by scribing or the like (FIG. 8E).

Here, FIG. 9 shows the relationship between the growth temperature and the stacked body.

An n-type GaN contact layer 3 at a substrate temperature of 1030 ° C. and an n-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
An N-type cooling layer 5 is stacked on the cladding layer 4 while the substrate temperature is lowered from 1100 ° C. to 790 ° C.
Are laminated. N-type Al _0.15 Ga _{0. 85} while the substrate temperature is 1100 ℃ ~1030 ℃ as n-type cooling layer 5 is more
N layer 51, n-type GaN layer 52 at a substrate temperature of 1030 ° C. to 850 ° C., n at a substrate temperature of 950 ° C. to 790 ° C.
A type Al _0.12 Ga _0.88 N layer 53 is laminated. Next, a multiple quantum well active layer 6 is laminated at a substrate temperature of 790 ° C., and then a multiple quantum well active layer 6 is laminated at a substrate temperature of 790 ° C.
While the temperature is raised to ° C., a p-type temperature raising layer 7 is laminated. More specifically, the p-type Al _0.05 Ga _0.95 N layer 71 is used as the p-type temperature raising layer 7 when the substrate temperature is between 790 ° C. and 950 ° C., and the substrate temperature is 950.
The p-type GaN layer 72 has a substrate temperature of 1 ° C. to 1050 ° C.
The p-type Al _0.12 Ga _0.88 N layer 73 is laminated between 050 ° C. and 1100 ° C. P-type A at 1100 ° C substrate temperature
A l _0.1 Ga _0.9 N cladding layer 8 and a p-type GaN contact layer 9 are sequentially laminated at a substrate temperature of 1030 ° C.

According to the device structure of the present invention, n-type AlGa
On the N cladding layer 4, an n-type AlGa
An N layer 51, an n-type GaN layer 52, and an n-type AlGaN layer 53 are sequentially arranged, and the n-type GaN layer 52 has a substrate temperature of 1030 ° C.
Grow between ９950 ° C. Substrate temperature 1030 ° C-9
By growing at 50 ° C., the n-type GaN layer 52 is stacked while maintaining good crystallinity. N-type A due to strain
Dislocations generated in the lGaN cladding layer 4 are absorbed by the n-type GaN layer 52, and the density of threading dislocations into the InGaN multiple quantum well active layer 6 decreases.

Further, on the InGaN multiple quantum well active layer 6, a p-type AlGaN layer 71 as a p-type temperature raising layer 7,
A p-type GaN layer 72 and a p-type AlGaN layer 73 are sequentially arranged, and the p-type GaN layer 72 has a substrate temperature of 1030 ° C. to 95 ° C.
Grow during 0 ° C. Substrate temperature is 1030 ℃ ～ 950 ℃
The p-type GaN layer 72 is stacked while maintaining good crystallinity. P-type AlGa
Dislocations generated in the N cladding layer 8 are absorbed by the p-type GaN layer 72, and the density of threading dislocations into the InGaN multiple quantum well active layer 6 is reduced. Therefore, the dislocations are p-type impurities via the threading dislocations. Mg diffusion is reduced, and deterioration of the crystallinity of the active layer can be suppressed.

For this reason, a light emitting device having more excellent luminous efficiency and reliability than the semiconductor lasers of the first and second embodiments can be realized.

The method for manufacturing a semiconductor light-emitting device according to the present invention includes a step of laminating at least a clad layer on a semiconductor substrate, a step of laminating the temperature-lowering layer while lowering the substrate temperature, a single or multiple quantum well active layer. Laminating, the step of laminating the heating layer while raising the substrate temperature,
This achieves the above object.

(Embodiment 4) FIG. 10 shows a first embodiment of the present invention.
1 is a schematic sectional view of a semiconductor laser according to an embodiment.
This semiconductor laser device has a sapphire substrate 1 on which Ga
N buffer layer 2, n-type GaN contact layer 3, n-type Al
GaN cladding layer 4, n-type cooling layer (n-type AlGaN layer 5)
1, an n-type GaN layer 52), an InGaN single quantum well active layer 6, a p-type AlGaN cladding layer 8, and a p-type GaN contact layer 9 in this order. 10 is a p-type electrode and 11 is an n-type electrode. According to the semiconductor laser device of the present invention, the n-type cooling layer 5, that is, the n-type AlGaN layer 51 and the n-type GaN layer 52
Are stacked between the n-type AlGaN cladding layer 4 and the InGaN single quantum well active layer 6.

Next, the manufacturing process of this semiconductor laser will be described. MOCV for fabrication of gallium nitride based semiconductor laser
Using method D, a sapphire substrate was used as a substrate, ammonia NH ₃ was used as a group V material, and TMG and TM were used as a group III material.
A, TMIn, CP ₂ Mg as a p-type impurity, SiH ₄ as an n-type impurity, and H ₂ and N as carrier gases.
_{Use 2} .

First, the sapphire substrate 1 is introduced on the susceptor of the MOCVD apparatus. The substrate temperature is raised to 1200 ° C., and the surface of the substrate is cleaned in an atmosphere of H ₂ and N ₂ . Next, a GaN buffer layer 2 (50 nm thick) is laminated on the sapphire substrate 1 at a substrate temperature of 540 ° C. N-type GaN contact layer 3 (4 μm thickness) at a substrate temperature of 1050 ° C., n-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
An N clad layer 4 (0.15 μm thick) is laminated.

Next, the N-type Al _0.1 Ga _0.9 N clad layer 4
While the substrate temperature is lowered from 1100 ° C. to 750 ° C., an n-type Al _0.30 Ga _0.70 N layer 51 (thickness: 50 nm), n
A GaN layer 52 (80 nm thick) is laminated.

Here, it is preferable that the n-type Al _0.30 Ga _0.70 N layer 51 grows at a substrate temperature of 1100 ° C. to 1050 ° C., and the n-type GaN layer 52 grows at a substrate temperature of 1050 ° C. to 750 ° C.

Next, at a substrate temperature of 750 ° C., In _0.3 Ga
_{A 0.7} N quantum well active layer (thickness: 3 nm) 6 is laminated.

Next, the substrate temperature was raised to 1100 ° C., and the p-type Al _0.1 Ga _0.9 N clad layer 8 (thickness 0.15 μm) was formed.
At a substrate temperature of 1050 ° C., a p-type GaN contact layer 9 (thickness: 0.3 μm) is sequentially laminated.

Next, the wafer is taken out of the MOCVD apparatus, a resist mask is formed on the p-type GaN contact layer 9 as a dry etching mask, and the surface of the n-type GaN contact layer 3 is exposed by dry etching.

Next, an n-type electrode 11 is formed on the exposed surface of the n-type GaN contact layer 3 and a p-type electrode 10 is formed on the surface of the p-type GaN contact layer 9. Finally, 350 μm in width,
When the chip is divided into chips with a length of 600 μm by scribing or the like, a semiconductor laser device is manufactured.

Here, the relationship between the growth temperature and the stacked body will be described.

An n-type GaN contact layer 3 at a substrate temperature of 1050 ° C. and an n-type Al _0.1 Ga _0.9 at a substrate temperature of 1100 ° C.
An N-type cooling layer 5 is stacked on the cladding layer 4 while the substrate temperature is lowered from 1100 ° C. to 750 ° C.
Are laminated. N-type Al _0.30 Ga _{0. 70} while the substrate temperature is 1100 ° C. to 1050 ° C. as n-type cooling layer 5 is more
An N layer 51 and an n-type GaN layer 52 are laminated at a substrate temperature of 1050 ° C. to 750 ° C. Next, the substrate temperature is 750 ° C.
In _0.3 Ga _0.7 N quantum well active layer (thickness 3 nm)
6, a p-type Al _0.1 Ga _0.9 N cladding layer 8 at a substrate temperature of 1100 ° C., and a p-type GaN contact layer 9 at a substrate temperature of 1050 ° C. are sequentially stacked.

According to the device structure of the present invention, n-type AlGa
On the N cladding layer 4, an n-type AlGa
An N layer 51 and an n-type GaN layer 52 are sequentially stacked to form an n-type Ga
The N layer 52 grows when the substrate temperature is between 1050 ° C. and 750 ° C. By growing at a substrate temperature between 1050 ° C. and 750 ° C., the n-type GaN layer 52 is laminated while maintaining good crystallinity. N-type AlGaN cladding layer 4 due to strain
Are generated in the nGaN layer 52, and the density of threading dislocations to the active layer decreases. Therefore, a light-emitting element having excellent luminous efficiency and reliability can be obtained.

In the first to fourth embodiments, the embodiments using the sapphire substrate as the substrate have been described. Even when the GaN substrate is used, the same effects as those obtained in the first to fourth embodiments can be obtained. Have confirmed. Regarding the plane orientation of the GaN substrate, the [0001] plane, [1-10
0] plane, [11-20] plane, [1-101] plane, [11-2] plane
2] plane and [01-12] plane.
It has been confirmed that the same effects as those of the present invention can be obtained even if they are shifted by about degrees.

In the first to fourth embodiments, the temperature-lowering layer and the temperature-raising layer are formed while the temperature is lowered or raised, respectively. However, the temperature is intermediate between the growth temperatures of the active layer and the cladding layer, for example, the active layer. Is 750 ° C., the n-type cladding layer is 1100 ° C., and the n-type AlGaN layer 51 in the cooling layer is 950 ° C.
℃, n-type GaN 52 is 950 ° C., n-type AlGaN layer 53
Can be obtained at 950 ° C. to obtain the same effect. Similarly, the p-type AlGaN layer 71 in the heating layer is 950 ° C.
The N layer 72 is 950 ° C., and the p-type AlGaN layer 73 is 950 ° C.
When formed in the same manner, the same effect as in the example was obtained.

Further, in all of the first to third embodiments, the temperature-lowering layer and the temperature-raising layer are each formed of three layers. However, even if the AlGaN layer 51 or 73 in contact with the cladding layer is included in the cladding layer. I don't care. In this case, AlGa
When a layer corresponding to the N layer 51 is included in the clad layer, it is desirable that the temperature be lowered during the formation of the clad layer 4 and that the temperature be lowered to about 1050 ° C. to 750 ° C. when the GaN layer 52 is formed. Similarly, when a layer corresponding to the AlGaN layer 73 is included in the clad layer, it is desirable to start growth at about 750 ° C. to 1050 ° C. when forming the clad layer 8 and then raise the temperature to 1100 ° C.

Further, even if it is a clad layer, the clad layer is removed from the clad layer of the present invention by the temperature-lowering layers 51, 52,
The same effect as that of the present invention can be obtained when the growth is performed by changing the temperature in the same manner as in the case of the temperature raising layer 53 or the temperature raising layers 71, 72, 73.

[0085]

According to the device structure and device manufacturing conditions of the present invention, an n-type GaN layer 52 that forms an n-type cooling layer 5 by stacking an n-type cooling layer on the n-type AlGaN cladding layer 4 is formed.
Since the substrate temperature is grown between 1030 ° C. and 950 ° C., the n-type GaN layer 52 is stacked while maintaining good crystallinity. Therefore, dislocations generated in the n-type AlGaN cladding layer 4 due to strain are absorbed by the n-type GaN layer 52,
The threading dislocation density into the InGaN multiple quantum well active layer 6 decreases.

Further, a p-type heating layer 7 is laminated on the InGaN multiple quantum well active layer 6, and the p-type GaN layer 72 constituting the p-type heating layer 7 has a substrate temperature of 1030 ° C. to 95 ° C.
Since it is grown at 0 ° C., the p-type GaN layer 72 is stacked while maintaining good crystallinity. Mg which is a p-type impurity
Are contained in the p-type AlGaN cladding layer 8 and the GaN contact layer 9, so that diffusion into the active layer via dislocations generated in the p-type AlGaN cladding layer 8 due to strain is reduced. This is because the dislocation generated in the p-type AlGaN cladding layer 8 due to the strain is absorbed by the p-type GaN layer 72 and the dislocation to the InGaN multiple quantum well active layer 6 is reduced. Mg as an impurity
Is reduced, and deterioration of the crystallinity of the active layer can be suppressed.

As a result, a gallium nitride-based compound semiconductor light emitting device having excellent luminous efficiency and reliability can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a gallium nitride-based compound semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a gallium nitride-based compound semiconductor light emitting device according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of a gallium nitride-based compound semiconductor light emitting device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram of the fabrication of the gallium nitride-based compound semiconductor light emitting device of Embodiment 1.

FIG. 5 is a diagram illustrating a relationship between a growth temperature and a stacked body according to the first embodiment.

FIG. 6 is a schematic diagram illustrating the fabrication of a gallium nitride-based compound semiconductor light emitting device of Embodiment 2.

FIG. 7 is a diagram illustrating a relationship between a growth temperature and a stacked body according to a second embodiment.

FIG. 8 is a schematic diagram of a gallium nitride-based compound semiconductor light emitting device according to a third embodiment.

FIG. 9 is a relationship diagram between a growth temperature and a stacked body according to a third embodiment.

FIG. 10 is a schematic sectional view of a gallium nitride-based compound semiconductor light emitting device according to a fourth embodiment of the present invention.

FIG. 11 is a schematic sectional view illustrating a conventional gallium nitride-based compound semiconductor laser.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sapphire substrate 2 GaN buffer layer 3 n-type GaN contact layer 4 n-type AlGaN cladding layer 5 n-type cooling layer 51 n-type AlGaN layer 52 n-type GaN layer 53 n-type AlGaN layer 6 InGaN Quantum structure active layer 7 p-type heating layer 71 p-type AlGaN layer 72 p-type GaN layer 73 p-type AlGaN layer 8 p-type AlGaN cladding layer 9 p-type GaN contact layer 10 p-type electrode 11 n-type electrode 12... exposed surface of n-type GaN contact layer 3

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) AA55 AA73 CA07 CB05 CB07 CB10 CB19 DA05 DA24 EA29

Claims (8)

[Claims] 1. A gallium nitride based compound semiconductor light emitting device containing indium and aluminum having a pair of cladding layers and a quantum well active layer on a substrate, wherein a cladding layer is provided between at least one of the cladding layers and the quantum well active layer. A gallium nitride-based compound semiconductor light emitting device having a laminated structure formed at a temperature lower than the growth temperature of the semiconductor layer and higher than the growth temperature of the quantum well active layer. 2. The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein the stacked structure includes a GaN layer. 3. The laminated structure has at least one layer of Al.
2. A GaN layer and a GaN layer.
3. The gallium nitride-based compound semiconductor light-emitting device according to item 1. 4. The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein the laminated structure is a three-layer structure including a GaN layer sandwiched between a pair of AlGaN layers. 5. The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein said laminated structure is formed on both sides of an active layer. 6. A process for forming a Al _X Ga _1-X N cladding layer on a substrate, method of manufacturing a gallium nitride-based compound semiconductor light-emitting device comprising a step of forming a quantum well active layer at a temperature lower than that of the clad layer A gallium nitride-based compound semiconductor light emitting device, wherein a stacked structure is formed between at least one clad layer and the quantum well active layer at a temperature lower than the clad layer and at a temperature higher than the quantum well active layer. Manufacturing method. Forming a 7. Al _X Ga _1-X N cladding layer on a substrate, forming a laminated structure by lowering the substrate temperature, further the step of forming the quantum well active layer by lowering the substrate temperature 6. The gallium nitride based compound semiconductor light emitting device according to claim 5, further comprising: increasing the substrate temperature again to form a laminated structure; and further increasing the substrate temperature to form a cladding layer. Production method. 8. The method according to claim 6, wherein the formation temperature of the laminated structure is changed intermittently or stepwise between the cladding layer formation temperature and the quantum well active layer formation temperature.
The method for producing a gallium nitride-based compound semiconductor light-emitting device according to any one of the above.