JPH06140714A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To constitute a refractive index waveguide type visible light laser in the self-alignment manner by one time growth, by selectively forming a semi-insulating current blocking layer doped with oxygen, on a substrate having the slant of a trench, a ridge, etc. CONSTITUTION:A slant having an A face is formed by selectively etching an N-GaAs substrate 1 having a main surface inclined to the A face side. On the slant, an N-GaAs buffer layer 2 and an N-type AlGaInP clad layer 3 are grown, and thereon an AlGaInP layer is grown by simultaneous doping of Si and O. An N-type AlGaInP clad layer 41 is formed on the slant. An Si-AlGaInP current- blocking layer 42 is formed on the main surface. Thereby a refractive index waveguide type visible light laser can be constituted in the self-alignment manner by one time growth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly to a visible light region semiconductor laser having a wavelength band of 600 to 800 nm. In recent years, there has been an increasing demand for a semiconductor light emitting device such as a visible light laser using an AlGaInP-based material as a light source for reading a high density information recording optical disk, a light source for writing, a light source for POS, a light source for a printer and the like.

[0002]

2. Description of the Related Art FIG. 10 is a diagram showing the construction of the most conventional conventional visible light laser. The visible light laser with this structure is
It is a refractive index guided laser called a loss guide type.
In this figure, 11 is a GaAs substrate and 12 is n-type Al.
GaInP clad layer, 13 is a GaInP active layer, 14
Is a p-type AlGaInP cladding layer, and 15 is a p-type GaIn
A P intermediate layer, 16 is an n-type GaAs current blocking layer, and 17 is a p-type GaAs contact layer.

In this conventional visible light laser, an n-type AlGaInP clad layer 12, a GaInP active layer 13, and a p-type AlGaI are formed on a flat (100) surface of a GaAs substrate 11.
AlGaInP / GaIn composed of nP clad layer 14
P double hetero (DH) structure and p-type GaInP
The intermediate layer 15 is continuously grown (first growth), and a <01-1> direction is formed on the p-type GaInP intermediate layer 15 (this "-1" is usually a bar on "1". SiO ₂ stripes formed by means which expressed), the Si
Using the O ₂ stripe as a mask, the p-type GaInP intermediate layer 15 and part of the p-type AlGaInP clad layer 14 are selectively removed by etching to form a ridge structure, and the SiO ₂ stripe on the ridge structure is masked. And n type G
The aAs current blocking layer 16 is grown (second growth), the SiO ₂ stripe is removed, and the p-type GaA is formed on the p-type GaInP intermediate layer 15 and the n-type GaAs current blocking layer 16.
It is configured by growing the s contact layer 17 (third growth).

The conventional visible light laser thus constructed has the advantage that good characteristics can be obtained relatively easily.

[0005]

As described above, this conventional visible light laser has an advantage that good characteristics can be obtained relatively easily, but it is complicated to perform crystal growth three times. is there. Therefore, an object of the present invention is to provide a visible light semiconductor light emitting device that can be manufactured by a simpler method.

[0006]

In a semiconductor light emitting device according to the present invention, a double layer having first and second clad layers and a light emitting active region layer sandwiched between the first clad layer and the second clad layer is provided. The double heterostructure has a hetero structure, and the double hetero structure is formed on a substrate in which a slope is partially formed on a flat main surface, and the main surface orientation of the substrate is (100).
In the plane, the (h11) A plane (h ≧ 1) appears on the slope, and the n-type cladding layer formed on the substrate is simultaneously doped with oxygen and Si which is an n-type impurity. We adopted a structure in which the electron concentration on the main surface of the cladding layer is lower than the electron concentration on the slope.

In this case, oxygen and p-type impurities are contained in the p-type clad layer formed on the substrate in which the principal plane orientation is (100) and the (h11) A plane (h ≧ 1) appears on the slope. Zn
Alternatively, Mg can be doped at the same time so that the hole concentration on the main surface of the p-type cladding layer is lower than the hole concentration on the inclined surface, and the main surface orientation is the (100) plane, and h1
1) p formed on the substrate where the B surface (h ≧ 1) appears
Oxygen and Zn, which is a p-type impurity, can be simultaneously doped into the type clad layer to make the hole concentration on the main surface of the p-type clad layer higher than the hole concentration on the inclined surface.

In these cases, in order to obtain a desired emission wavelength, the substrate is GaAs, the clad layer and the active layer are AlG.
The substrate can be made of aInP, or the substrate can be made of GaAs and the clad layer and the active layer can be made of AlGaAs.

[0009]

According to the present invention, a semi-insulating current blocking layer doped with oxygen is selectively formed on a substrate having a sloped surface such as a groove or a ridge, and self-aligned by one growth. A refractive index guided visible light laser can be constructed.

FIG. 2 is a diagram showing the relationship between the oxygen doping amount and the carrier concentration, where (A) is n-type AlGaInP and (B).
Indicates the carrier concentration when p-type AlGaInP is doped with oxygen. From this figure, p-type AlGaInP
As for the n-type AlGaInP, it can be seen that the carrier concentration decreases as the oxygen doping amount increases, and finally the crystal becomes high in resistance or semi-insulating.

This is because, as previously revealed by the inventors of the present invention, oxygen creates a deep level in AlGaInP, and this level has the effect of trapping electrons and holes. Yes (J. Appl. Phys., Vo
l. 70, p. 4946 (1991)). Therefore, oxygen-doped semi-insulating AlGaInP is very effective as a current blocking layer of a laser device.

[0012] Now, the inventors of the present invention have previously used M, which is used in crystal growth for manufacturing a visible light laser, for example.
In the OVPE method, impurities (Si, Se, Zn, Mg, etc.)
However, it was clarified that the amount of incorporation into the crystal remarkably depends on the plane orientation (J. Crystal Growth,
(During printing), and more recently, it has been found that the amount of oxygen taken into the crystal also remarkably depends on the crystal plane orientation.

FIG. 3 is a plane orientation dependence characteristic diagram of oxygen concentration in AlGaInP. This figure shows AlGaInP
When the substrate is doped with oxygen, the relationship between the inclination angle (degree) from the (100) plane of the substrate and the oxygen concentration standardized with the oxygen concentration of the (100) plane as 1. In addition,
In the (111) A plane direction data, the degree of decrease seems to be small due to the detection limit of SIMS, but it is actually decreased as indicated by the dotted line from the measurement of the deep level density caused by oxygen. (See Solid State Conference 1992, p.300).

From this figure, when the oxygen concentration of the (100) plane is used as a reference, the oxygen concentration decreases remarkably as the tilt angle of the substrate in the (111) A plane direction increases, and the oxygen concentration of the substrate in the (111) B direction increases. It can be seen that it does not change significantly depending on the tilt angle. This is the same characteristic as the relationship between the inclination angle of the substrate and the amount of incorporation when doping other VI group impurities (Se, S, Te) or the like.

Also, regarding other impurities, it is known that the amount of impurities taken in depends on the tilt angle of the substrate.
An example will be examined below for Si, Zn, and Mg.

FIG. 4 is a plane orientation dependence characteristic diagram of the Si concentration in AlGaInP. This figure shows AlGaInP
It shows the relationship between the relative silicon concentration and the relative carrier concentration, and the inclination angle (degree) from the (100) plane of the substrate when the substrate is doped with silicon (Si).

In this figure, the case where SiH ₄ is used to dope silicon, the case where Si ₂ H ₆ is used to dope silicon, the growth temperature is 690 ° C., and the case where the growth temperature is 730 ° C.
It is shown for the case of ° C. From this figure, it can be seen that the relative Si concentration and the relative carrier concentration have almost no plane orientation dependence.

FIG. 5 is a plane orientation dependence characteristic diagram of Zn and Mg concentrations in AlGaInP. This figure shows Al
When the GaInP substrate is doped with Zn and Mg,
The relationship between the inclination angle (degree) from the (100) plane of the substrate, the concentrations of Zn and Mg, and the carrier concentration is shown.

From this figure, Zn and Mg are both (10
The tilt angle of the substrate from the (0) plane toward the (111) A plane is (3
It increases remarkably when it grows to the (11) plane, and becomes (111) B
It can be seen that it does not change significantly depending on the tilt angle of the substrate in the direction. Therefore, by simultaneously doping oxygen and other impurities, the difference in the plane orientation dependence of the uptake amount of oxygen and other impurities is utilized, and the light emission active region is partially formed in the cladding layer on the shaped substrate. Layers and current blocking layers can be built in.

6A and 6B are explanatory views (1) of the principle of the method of forming a current blocking layer by simultaneous doping with oxygen and impurities, where (A) shows the cross section of the cladding layer and (B) shows the relationship between the orientation of the substrate and the concentration. Is schematically shown. According to this method of forming a current blocking layer, the (100) plane is the main plane, and the (h11) A plane (h
On the substrate having a slope of ≧ 1), an n-type region is formed on the slope and a semi-insulating oxygen concentration is formed on the main surface by growing a clad layer while simultaneously doping Si, which is an n-type impurity, and oxygen. Can form a high area (SI).

Using this principle, a double hetero structure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer is provided. , The main surface of the substrate is a (100) plane, and the (h11) A
Surface (h ≧ 1) appears, and the electron concentration on the main surface is lower than the electron concentration on the slope of the n-type cladding layer. A semiconductor light emitting device having a light emitting active region layer on the slope. Can be configured.

FIG. 7 is a diagram (2) for explaining the principle of a method for forming a current blocking layer by simultaneous doping with oxygen and impurities. (A) shows the cross section of the cladding layer, and (B) shows the relationship between the substrate orientation and the concentration. Is schematically shown. According to this method of forming a current blocking layer, the (100) plane is the main plane, and the (h11) A plane (h
On a substrate having a slope of ≧ 1), a p-type region is formed on the slope and a semi-insulating oxygen concentration is formed on the main surface by growing a cladding layer while simultaneously doping Zn which is a p-type impurity and oxygen. Can form a high area (SI).

Using this principle, a double hetero structure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer is provided. , The main surface of the substrate is a (100) plane, and the (h11) A surface (h ≧ 1) is formed on the flat surface. And the hole concentration on the main surface is lower than the hole concentration on the slope of the p-type cladding layer, and a semiconductor light emitting device having a light emitting active region layer on the slope can be configured. it can.

FIG. 8 is a diagram (3) for explaining the principle of a method for forming a current blocking layer by simultaneous doping with oxygen and impurities. (A) shows the cross section of the cladding layer, and (B) shows the relationship between the orientation of the substrate and the concentration. Is schematically shown. According to this method of forming a current blocking layer, the (100) plane is the main plane, and the (h11) A plane (h
On the substrate having a slope of ≧ 1), a p-type region is formed on the slope by growing a cladding layer while simultaneously doping p-type impurities Mg and oxygen, and a semi-insulating oxygen concentration is formed on the main surface. Can form a high area (SI).

When this principle is used, as in the case of the principle of FIG. 7, the first and second cladding layers and the light emitting active region layer sandwiched between the first and second cladding layers are provided. The double hetero structure has a double hetero structure formed on a substrate having a partially inclined surface on a flat main surface, and the main surface orientation of the substrate is (10
In the (0) plane, this slope (h11) A plane (h ≧ 1) appears, and the hole concentration on the main surface is lower than the hole concentration on the slope of the p-type cladding layer. A semiconductor light emitting device having a light emitting active region layer on the slope can be configured.

FIG. 9 is a diagram (4) for explaining the principle of a method for forming a current blocking layer by simultaneous doping with oxygen and impurities. (A) shows the cross section of the cladding layer, and (B) shows the relationship between the orientation of the substrate and the concentration. Is schematically shown. According to this method of forming a current blocking layer, the (100) plane is the main surface and the (h11) B plane (h
On the substrate having a slope of ≧ 1), a p-type region is formed on the main surface by growing a cladding layer while simultaneously doping p-type impurities Mg and oxygen, and a semi-insulating oxygen concentration is formed on the slope. Can form a high area (SI).

Using this principle, a double hetero structure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer is provided. Is formed on a substrate in which a slope is partially formed on a flat main surface, and the main surface orientation of the substrate is the (100) plane, and the (h11) B surface (h ≧ 1) is formed on this slope. And the hole concentration on the main surface is higher than the hole concentration on the slope of the p-type cladding layer, and a semiconductor light emitting device having a light emitting active region layer on the main surface is to be configured. You can

In the above embodiment, for a semiconductor light emitting device having a wavelength of 550 to 700 nm, the substrate is GaAs, the clad layer is the active layer, and the active layer is AlGaI, depending on the desired emission wavelength.
For a semiconductor light emitting device having a thickness of nP and a wavelength of 750 to 850 nm, the substrate can be made of GaAs, the clad layer, and the active layer can be made of AlGaAs.

[0029]

EXAMPLE An example of the present invention will be described below. Figure 1
FIG. 3 is a configuration explanatory view of a semiconductor light emitting device of one embodiment of the present invention. The semiconductor light emitting device of this embodiment shows a case where the present invention is applied to the previously proposed slope laser having a light emitting region on the (311) A slope (see Japanese Patent Application No. 4-132304).

In this figure, 1 is an n-GaAs substrate,
2 is an n-GaAs buffer layer, 3 is an n-type AlGaInP
Cladding layer, 4 ₁ n-type AlGaInP cladding layer, 4
₂ is S. I-AlGaInP current blocking layer, 5 is GaIn
P active layer 6 is p-AlGaInP cladding layer, 7 ₁ p-AlGaInP cladding layer, 7 ₂ n-AlGaI
nP current blocking layer, 8 is p-GaInP intermediate layer, 9 is p-
It is a GaAs contact layer.

An example of a method of manufacturing the semiconductor light emitting device of this embodiment will be described together with the description of the structure thereof.

(1) n-G having a (100) plane or a major surface inclined to the (111) A plane side by 6 ° from the (100) plane
By selectively etching the aAs substrate (Si-doped) 1, a slope having a (311) A plane is formed.

(2) On top of that, an n-GaAs buffer layer (Si-doped, impurity concentration n = 1 × 10 ¹⁸ cm ⁻³ , layer thickness 0.5 μm) 2 and an n-type AlGaInP clad layer (S
i-doped, n = 5 × 10 ¹⁷ cm ⁻³ , 1 to 2 μm) 3 is grown, on which Si and O are simultaneously doped to form AlGa.
An InP layer is grown, and an n-type AlGaInP cladding layer (Si-doped, n = 5 × 10 ¹⁷ cm ⁻³ , 1-2 μ) is formed on the slope.
m) 4 ₁ is formed, S. on the major surface I-AlGaInP
A current blocking layer (O-doped) 4 ₂ is formed.

(3) On top of that, a GaInP active layer (undoped, 0.015 to 0.1 μm) 5, p-AlGaI.
nP clad layer (Zn-doped, p = 1 × 10 ¹⁸ cm ⁻³ ,
0.5 μm) 6 is formed.

(4) Then, Zn and Se are simultaneously doped to grow an AlGaInP layer, and p-Al is formed on the slope.
GaInP clad layer (Zn-doped, p = 1 × 10 ¹⁸ c
m ⁻³ , 0.5 μm) 7 ₁ , and n-Al is formed on the main surface.
GaInP current blocking layer (Se-doped, n = 5 × 10 ¹⁷ c
m ⁻³ , 1 to 1.5 μm).

(5) A p-AlGaInP clad layer 7 ₁ and a p-GaAs contact layer 9 to be formed later are formed on the p-AlGaInP clad layer 7 _1.
P-Ga for reducing potential spikes that occur during
InP intermediate layer (Zn-doped, p = 1 × 10 ¹⁸ cm ⁻³ ,
0.1 μm) 8 and a p-GaAs contact layer (Zn-doped, p = 1 × 10 ¹⁹ cm ⁻³ , 5 μm) 9 are formed.

In the present invention, particularly in this embodiment, MOCVD is used as the epitaxial growth method of the semiconductor layer, and trimethyl indium (TM) is used as the semiconductor raw material.
I), triethylgallium (TEG), arsine (As
H ₃ ), phosphine (PH ₃ ), silane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is used as a raw material of silicon used as an n-type impurity, and cyclosilane is used as a raw material of Mg used as a p-type impurity. It is possible to use pentadiphenyl magnesium (Cp ₂ Mg) and dimethyl zinc (DMZn), diethyl zinc or the like as a raw material of Zn.
Hydrogen selenide (H ₂ Se) is used as a raw material for Se.

As the oxygen source, an oxygen gas diluted with hydrogen or an organic metal Al source containing oxygen such as (CH ₃ ) ₂ AlO (CH ₃ ) can be used. Also, hydrogen can be used as the carrier gas.
The growth temperature is 670 ° C to 730 ° C and the pressure is 50 to 7 ° C.
The carrier gas flow rate is 6 torr and 5 to 9 LM.

[0039]

As described above, according to the present invention,
Wavelength 6 that can be manufactured by a simple method with few crystal growth times
It is possible to provide a visible light semiconductor light emitting device in the band of 0 to 800 nm, and read an optical disc for high density information recording,
It contributes greatly in the technical fields related to writing light sources, POS light sources, printer light sources, and the like.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a relationship diagram between oxygen doping amount and carrier concentration, (A) is n-type AlGaInP, and (B) is p-type AlG.
It shows the carrier concentration when aInP is doped with oxygen.

FIG. 3 is a plane orientation dependence characteristic diagram of oxygen concentration in AlGaInP.

FIG. 4 is a plane orientation dependence characteristic diagram of Si concentration in AlGaInP.

FIG. 5 is a plane orientation dependence characteristic diagram of Zn and Mg concentrations in AlGaInP.

FIG. 6 is an explanatory view (1) of the principle of a method for forming a current blocking layer by simultaneous doping with oxygen and impurities, (A) showing a cross section of the cladding layer, and (B) schematically showing the relationship between the substrate orientation and the concentration. Is shown in.

7A and 7B are explanatory views (2) of the principle of a method for forming a current blocking layer by simultaneous doping of oxygen and impurities, (A) showing a cross section of the cladding layer, and (B) schematically showing the relationship between the orientation of the substrate and the concentration. Is shown in.

FIG. 8 is an explanatory view (3) of the principle of a method for forming a current blocking layer by simultaneous doping with oxygen and impurities, (A) showing a cross section of the cladding layer, and (B) schematically showing the relationship between the substrate orientation and the concentration. Is shown in.

FIG. 9 is an explanatory view (4) of the principle of a method for forming a current blocking layer by simultaneous doping with oxygen and impurities, (A) showing a cross section of the cladding layer, and (B) schematically showing the relationship between the orientation of the substrate and the concentration. Is shown in.

FIG. 10 is a structural explanatory view of a conventional most common visible light laser.

[Explanation of symbols]

1 n-GaAs substrate 2 n-GaAs buffer layer 3 n-type AlGaInP clad layer 4 ₁ n-type AlGaInP clad layer 4 ₂ S. I-AlGaInP current blocking layer 5 GaInP active layer 6 p-AlGaInP clad layer 7 ₁ p-AlGaInP clad layer 7 ₂ n-AlGaInP current blocking layer 8 p-GaInP intermediate layer 9 p-GaAs contact layer 11 GaAs substrate 12 n-type AlGaInP Cladding layer 13 GaInP active layer 14 p-type AlGaInP cladding layer 15 p-type GaInP intermediate layer 16 n-type GaAs current blocking layer 17 p-type GaAs contact layer

Claims (6)

[Claims] 1. A double heterostructure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer, the double heterostructure having a flat main structure. It is formed on a substrate in which a slope is partially formed on the surface, the principal plane orientation of the substrate is the (100) plane, and the (h11) A plane (h ≧ 1) appears on the slope. ,
Oxygen and Si, which is an n-type impurity, are simultaneously doped into the n-type cladding layer formed on the substrate, so that the electron concentration on the main surface of the n-type cladding layer is lower than the electron concentration on the slope. A semiconductor light emitting device characterized by the above. 2. A double heterostructure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer, the double heterostructure having a flat main structure. It is formed on a substrate in which a slope is partially formed on the surface, the principal plane orientation of the substrate is the (100) plane, and the (h11) A plane (h ≧ 1) appears on the slope. ,
Oxygen and Zn, which is a p-type impurity, are simultaneously doped into the p-type clad layer formed on the substrate, so that the hole concentration on the main surface of the p-type clad layer becomes lower than the hole concentration on the slope. A semiconductor light emitting device characterized in that. 3. A double heterostructure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer, the double heterostructure having a flat main structure. It is formed on a substrate in which a slope is partially formed on the surface, the principal plane orientation of the substrate is the (100) plane, and the (h11) A plane (h ≧ 1) appears on the slope. ,
Oxygen and Mg, which is a p-type impurity, are simultaneously doped into the p-type clad layer formed on the substrate, so that the hole concentration on the main surface of the p-type clad layer becomes lower than the hole concentration on the slope. A semiconductor light emitting device characterized in that. 4. A double heterostructure having first and second cladding layers and a light emitting active region layer sandwiched between the first cladding layer and the second cladding layer, the double heterostructure having a flat main structure. It is formed on a substrate in which a slope is partially formed on the surface, the main surface orientation of the substrate is the (100) face, and the (h11) B face (h ≧ 1) appears on the slope. ,
Oxygen and Zn, which is a p-type impurity, are simultaneously doped into the p-type clad layer formed on the substrate, so that the hole concentration on the main surface of the p-type clad layer becomes higher than the hole concentration on the slope. A semiconductor light emitting device characterized in that. 5. The semiconductor light emitting device according to claim 1, wherein the substrate is composed of GaAs, the clad layer and the active layer are composed of AlGaInP. 6. The semiconductor light emitting device according to claim 1, wherein the substrate is composed of GaAs, the clad layer and the active layer are composed of AlGaAs.