JPH08116092A - Semiconductor light emitting element and its manufacture - Google Patents

Abstract

PURPOSE: To provide a semiconductor light emitting element wherein the generation of crystal defect and dislocation due to the mismatching of lattice constant and the difference of thermal expansion coefficients are restrained to the utmost, and cleavage is possible, and a manufacturing method of the element. CONSTITUTION: Nitride gallium based compound semiconductors 4-9 are laminated on the main surface of a substrate 3 of III-V compound semiconductor, such as GaAs, InAs, GaP, and InP, wherein As or P atoms are the outermost surface, and a light emitting element is constituted.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device and a method for manufacturing the same. More specifically, it relates to a semiconductor light emitting device using a gallium nitride based compound semiconductor suitable for blue light emission and a method for manufacturing the same.

Here, a gallium nitride compound semiconductor is a compound of a group III element Ga and a group V element N or
A semiconductor made of a compound in which a part of Ga of the group III element is replaced with another group III element such as Al and In and / or a part of N of the group V element is replaced with another group V element such as P and As. Say.

A semiconductor light emitting device is a light emitting diode (hereinafter referred to as LED) having a double heterojunction such as a pn junction or a pin, a super luminescent diode (SLD) or a semiconductor laser diode (LD).
A semiconductor element that emits light.

[0004]

2. Description of the Related Art Conventionally, blue LEDs have a lower brightness than red and green and are difficult to put into practical use. In recent years, however, gallium nitride compound semiconductors have been used, and a low resistance p-type semiconductor layer doped with Mg has been formed. As a result, the brightness is improved and it is in the limelight.

A conventional gallium nitride based LED has a structure as shown in FIG. 5, for example. This LE
In order to manufacture D, first, a sapphire (Al ₂ O ₃ single crystal) substrate 21 is formed at a low temperature of 400 to 700 ° C. by a metal organic compound vapor phase growth method (hereinafter referred to as MOCVD method) together with a carrier gas H ₂ and an organic metal compound. A low temperature buffer layer 2 made of GaN by supplying trimethylgallium (hereinafter referred to as TMG) and ammonia (NH ₃ ) which are gases
2 is formed in the range of 0.01 to 0.2 μm, and then 700 to
The same gas is supplied at a high temperature of 1200 ° C. to form the high temperature buffer layer 23 made of n-type GaN having the same composition in a thickness of about 2 to 5 μm.

Then, a gas of trimethylaluminum (hereinafter referred to as TMA) is further supplied to the above-mentioned gas to form an n-type clad layer 24 of n-type Al _x Ga _{1 -x} N (0 <x <1). The thickness is about 1 to 0.3 μm, and an n-type clad layer for forming a double heterojunction is formed. To form these n-type layers, a source gas such as SiH ₄ is introduced at the same time.

Next, a material having a bandgap energy smaller than that of the cladding layer, for example, Ga _y , is produced by reducing the Al content and increasing the In content relative to the composition of the cladding layer.
An active layer 25 made of In _1-y N (0 <y ≦ 1) is formed.

Then, biscyclopentadienyl magnesium (hereinafter, Cp) for Mg or Zn as a p-type impurity is added to the same source gas as that for forming the n-type clad layer.
₂ Mg) or dimethylzinc (hereinafter referred to as DMZn) organometallic compound gas is added and introduced into the reaction tube,
A p _- type clad layer 26 made of p _- type Al _x Ga _1-x N is formed.

Further, in order to form the cap layer 27, the same gas as described above is supplied to vapor-deposit the p-type GaN layer.

After that, a protective film such as SiO ₂ is provided on the entire surface of the semiconductor growth layer, and the temperature is 400 to 800 ° C. and 20 to 6 ° C.
Annealing is performed for about 0 minutes to activate the p-type cap layer 27 and the p-type cladding layer 26. Then, after removing the protective film, in order to form an n-type electrode, a resist is applied and patterned, and as shown in FIG. 5, a part of each grown semiconductor layer is dried in an argon gas and chlorine gas atmosphere. N-type GaN by etching
The high temperature buffer layer 23 consisting of is exposed. Then A
A metal film of u, Al or the like is formed by sputtering or the like to form both electrodes 28 and 29, and the LED chip is formed by dicing.

[0011]

A conventional semiconductor light emitting device using a gallium nitride-based compound semiconductor has a sapphire substrate on the back side and is an insulator. Therefore, a complicated process such as etching is required to form an electrode on the back side. Will be needed.

Further, the sapphire substrate can withstand high temperatures and can be adjusted to relatively various crystal planes, so that it is advantageously used. However, the lattice constant of the sapphire substrate and the gallium nitride compound semiconductor crystal is Each 4.
Since 758Å and 3.189Å are significantly different and the thermal expansion coefficient is also different, dislocations and crystal defects occur in the buffer layer in contact with the sapphire substrate, as shown in A of FIG.
The crystal defects propagate to the gallium nitride-based compound semiconductor single crystal layer, which is the operating layer, and the operating region becomes narrower.
There is a problem that the optical quality of the semiconductor layer also deteriorates.

Further, since the sapphire substrate cannot be cleaved and the semiconductor light emitting device chip cannot be manufactured by the cleavage in the above-described structure, it is necessary to provide two parallel mirror surfaces with high precision like the semiconductor laser. There is a problem that the device is not suitable for.

It is an object of the present invention to solve the above problems and provide a semiconductor light emitting device in which the occurrence of crystal defects and dislocations due to the mismatch of lattice constants and the difference in thermal expansion coefficient is suppressed as much as possible, and a manufacturing method thereof. To do.

Still another object of the present invention is to use a gallium nitride-based compound semiconductor in a semiconductor light emitting device such as a semiconductor laser which requires two mirror surfaces parallel to the end surface and to obtain the end surface mirror surface by cleaving. An object of the present invention is to provide a semiconductor light emitting device that can be manufactured and a method for manufacturing the same.

[0016]

The semiconductor light emitting device of the present invention comprises a gallium nitride based compound semiconductor layer laminated on a III-V compound semiconductor substrate.

The gallium nitride based compound semiconductor layer is
By stacking the group V atom of the III-V group compound semiconductor on the outermost surface, the lattice matching at the interface becomes preferable.

It is preferable that the III-V compound semiconductor substrate is gallium arsenide for a semiconductor light emitting device having a structure containing gallium in the buffer layer.

It is preferable that the III-V compound semiconductor substrate is indium arsenide for a semiconductor light emitting device having a structure in which the buffer layer contains indium.

When the III-V compound semiconductor substrate is gallium phosphide, it is preferable for a semiconductor light emitting device that contains gallium in the buffer layer or has an emission wavelength of 550 nm or more.

It is preferable that the III-V compound semiconductor substrate is indium phosphide for a semiconductor light emitting device having a structure in which the buffer layer contains indium.

The gallium nitride based compound semiconductor layer is
It is preferable to have a plurality of layers including a p-type layer and an n-type layer and to have an active layer for light emission as a structure for easily realizing a light emitting element.

The gallium nitride based compound semiconductor layer is
It is preferable that the structure includes a buffer layer, a lower clad layer, an active layer, an upper clad layer, and a cap layer for realizing a light emitting device.

The buffer layer is n-type Ga _z In _{1 -z} N
(0 <z ≦ 1), the lower cladding layer is n-type Al _x Ga
_1-x N (0 <x <1), the active layer is Ga _y In _1-y N
(0 <y ≦ 1), the upper cladding layer is p-type Al _x Ga
_1-xN (0 <x <1) and it is preferable that the cap layer is p-type GaN in order to realize a light emitting device having a double hetero structure.

The manufacturing method of the semiconductor light emitting device of the present invention is III-V.
Preparing a Group III compound semiconductor substrate, stacking a gallium nitride based compound semiconductor buffer layer on the main surface of the III-V group compound semiconductor substrate, lower clad made of gallium nitride based compound semiconductor on the buffer layer A layer, an active layer, an upper clad layer and a cap layer, which are sequentially laminated with their crystal lattices aligned, on the cap layer and
The method includes a step of forming an electrode on the back surface of the III-V compound semiconductor substrate and a step of cleaving the chip for each element.

The step of stacking the buffer layer is a step of forming a low temperature buffer layer at a low temperature and a step of subsequently forming a high temperature buffer layer at a high temperature. It is preferable in preventing the occurrence of

The buffer layer is n-type Ga _z In _{1 -z} N
(0 <z ≦ 1), the lower cladding layer is n-type Al _x Ga
_1-x N (0 <x <1), the active layer is Ga _y In _1-y N
(0 <y ≦ 1), the upper cladding layer is p-type Al _x Ga
It is preferable that _1-x N (0 <x <1) and the cap layer be p-type GaN in order to realize a light emitting device having a double hetero structure.

It is preferable that the III-V group compound semiconductor substrate is prepared with the surface having the group V atom as the outermost surface as the main surface for good lattice matching at the interface.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a semiconductor light emitting device of the present invention will be described according to a manufacturing method with reference to the drawings. FIG. 1 is a cross-sectional explanatory view of a process of an embodiment of a method for manufacturing a semiconductor light emitting device of the present invention, and FIGS.

First, as shown in FIG. 1A, Ga
A III-V group compound semiconductor substrate 3 such as an As substrate, InAs substrate, GaP substrate or InP substrate is prepared. When any of the substrates 3 is used, the main surface uses the (111) plane, and the group V atom, that is, As or P, is used on the outermost surface.
Is exposed (hereinafter, referred to as (111) A plane). To obtain such a substrate, X-ray diffraction (11
1) Determine the plane direction, cut parallel to the (111) plane,
Since the surface with the larger atomic radius of the surface is the (111) A surface, the surface is observed with a tunnel current microscope (111)
It is obtained by processing so that the surface A becomes the surface of the substrate.

[0031] Then 1 as shown in (b), is disposed the substrate 3 into the reaction furnace, gallium nitride based compound semiconductor _{Al v Ga w In 1-vw} N (0 ≦ v <1, 0 <w ≦
1, 0 <x + w ≦ 1), and the low-temperature buffer layer 4 was made to have 0.
01 to 0.2 μm, the high temperature buffer layer 5 to 2 to 5 μm
Provide some degree. When a gallium nitride-based compound semiconductor single crystal is directly grown to form a gallium nitride-based compound semiconductor single crystal that directly becomes a clad layer or an active layer, crystal defects or dislocations due to lattice mismatch occur, but the low-temperature buffer layer Four
By providing the high temperature buffer layer 5, the clad layer and the active layer can be obtained in a clean crystal state, but the high temperature buffer layer 5 can be a part of the clad layer. This low-temperature buffer layer 4 is 400-70 by MOCVD method.
A polycrystalline film is grown at 0 ° C. for 0.01 to 0.2 μm. Following this, 700-1200 ° C
The high temperature buffer layer 5 is grown at the high temperature. When the high temperature buffer layer 5 is grown, the low temperature buffer layer 4 grown as a polycrystalline film at low temperature is also made into a single crystal, and the high temperature buffer layer 5 is formed.
Be aligned with.

Next, as shown in FIG. 1C, an n-type cladding layer 6, an undoped or n-type or p-type active layer 7, a p-type cladding layer 8 and a cap layer 9 are sequentially formed. The cladding layers 6 and 8 are usually formed to a thickness of about 0.1 to 2 μm, and the active layer 7 is formed to a thickness of about 0.02 to 0.2 μm. The active layer 7 is formed so thin that crystal defects and dislocations cannot occur, but there is a limit to how thin the clad layer is, and since it is thick, distortion is likely to occur if these are made of different materials. It is preferable that the thick layer together with the high temperature buffer layer 5 are made of a material having the same composition.

In order to form an n-type layer in the semiconductor layer such as the above-mentioned cladding layer, Si, Ge, Sn, Te, etc. are replaced with SiH.
It is obtained by mixing into the reaction gas as a gas such as ₄ , GeH ₄ , SnH ₄ , and TeH ₄ . Further, in order to form the p-type layer, Mg or Zn is replaced with Cp ₂ Mg or DMZn.
P by mixing with the source gas as the organometallic gas of
It can be a mold layer. This p-type layer is formed by forming a protective film made of SiO ₂ or the like on the cap layer 9 to 400 to 800
H combined with Mg by annealing at ℃ or by irradiating electron beam (H ₂ as carrier gas and H of NH ₃ gas as reaction gas combine)
Can be separated to facilitate the movement of Mg and lower the resistance.

In this example, a p-type layer and an n-type layer are provided on both sides of the active layer 7.
A double heterojunction structure sandwiched between both cladding layers 6 and 8 of the mold layer is formed, and the cladding layers 6 and 8 are made of a material having a bandgap energy larger than that of the active layer 7. The above-mentioned Al _v Ga _w In
To increase the bandgap energy of a _1-vw N material, increase v and decrease _1-vw . By making the sandwich structure with the cladding layers 6 and 8 having such band gap energy, the carriers injected into the active layer are confined by the energy barrier formed between the active layer, which is the light emitting layer, and the cladding layer. The establishment of radiative recombination is significantly improved and the luminous efficiency is also higher than the homojunction structure in which a pn junction is made of the same material. However, the manufacturing method of the present invention is not limited to such a double heterojunction structure, and is similarly applied to a homojunction or heterojunction pn junction only by changing the composition of the semiconductor layer to be grown. Further, a semiconductor light emitting device having a refractive index waveguide structure can be similarly manufactured by forming a stripe groove with a semiconductor laser. The cap layer 9 is for reducing the contact resistance with the electrode and is formed to have a thickness of about 0.2 to 2 μm.

Next, as described above, a protective film of SiO ₂ , Si ₃ N ₄ , GaAs, InP or the like is provided on the surface of the semiconductor layer and annealed at 400 to 800 ° C. for about 20 to 60 minutes. The electron beam irradiation with an accelerating voltage of about 3 to 20 kV is directly performed from the surface without providing a protective film. As a result, the bond between Mg and H, which are dopants in the p-type layer, is cut, activation is achieved, and the resistance of the p-type layer is reduced.

Then, an electrode material such as Au or Al is deposited by vapor deposition or sputtering, a lower (n-side) electrode 11 is formed on the entire back surface, and a light emitting region in the case of an LED on the front surface side. In order to secure the above, or to regulate the current injection region in the case of a semiconductor laser, the upper (p-side) electrode 10 is formed by patterning only the central portion, and then cleaved in each chip. A semiconductor light emitting device chip is formed as shown in a perspective view in d).

The semiconductor light emitting device chip is placed on a lead frame, wire bonded, and then molded with an epoxy resin to complete an LED.

According to the present invention, as a substrate for growing a gallium nitride based compound semiconductor layer, a GaAs substrate,
II such as InAs substrate, GaP substrate or InP substrate
Since the I-V group compound semiconductor substrate is used, the lattice constant and the thermal expansion coefficient of the semiconductor growth layer and the substrate are very close to each other, and lattice defects and dislocations are hard to occur at the interface. In particular, the coefficient of thermal expansion is Ga as compared with the sapphire substrate that has been conventionally used.
Since it is close to N, the occurrence rate of lattice strain due to heat treatment during the manufacturing process is significantly reduced.

As the main surface of these substrates, a surface closest to the C-plane of the conventional sapphire substrate is selected, and the gallium nitride compound is used by using it in a state where the outermost surface is a group V atom. Lattice mismatch between the semiconductor layer and the semiconductor layer is unlikely to occur, and dislocations and crystal defects are less likely to spread to the gallium nitride-based compound semiconductor single crystal layer serving as the operating layer. When the outermost surface is a group V atom, the substrate surface is likely to be nitrided, and the crystal planes of the stacked gallium nitride-based compound semiconductor layers are likely to be regularly aligned.

Further, the buffer layer and the clad layer have a thickness of 1 μm.
By setting the composition of the semiconductor single crystal layer of the layer formed thicker to the same as above, a clean cleavage plane can be obtained and a mirror surface can be easily obtained.

Further, if a substrate material containing the same group III atoms as the buffer layer is used, the strain at the interface between the buffer layer and the substrate is small.

[0042]

EXAMPLES Next, the present invention will be described in detail with reference to more specific light emitting devices.

Example 1 FIG. 2 is a cross-sectional explanatory view of a double heterojunction LED using a gallium nitride based compound semiconductor manufactured by the manufacturing method of the present invention. Al _v as a gallium nitride compound semiconductor
_{Ga w In 1-vw N (} 0 ≦ v <1,0 <w ≦ 1,0 <v
+ W ≦ 1) and the double heterojunction is formed by changing the ratio of Al, Ga and In.

First, GaAs and InA formed to a thickness of 50 to 500 μm as shown in FIG.
s, GaP or InP on the surface of the substrate 400 ~
At a low temperature of 700 ° C. n-type _{Al v Ga w In 1-vw} N (0 ≦
v <1, 0 <w ≦ 1, 0 <v + w ≦ 1, for example v =
The low temperature buffer layer 4 composed of 0, w = 1) is 0.01 to
About 0.2 μm was grown by MOCVD and then 70
At a high temperature of 0-1,200 ° C. provided a high-temperature buffer layer 5 made of n-type _{Al v Ga w In 1-vw} N having the same composition as the low-temperature buffer layer 4 to a thickness of about 2 to 5 [mu] m. Further 700-1
At 200 ° C. n-type _{Al x Ga y In 1-xy} N (0 <x <
1, 0 <y <1, 0 <x + y ≦ 1, v ≦ x, for example x
+ Y = 1) with an n-type cladding layer 6 of 0.1 to 2 μm
Al _p Ga _q In
_1-pq N (0 ≦ p <1, 0 <q ≦ 1, 0 <p + q <1,
p <x, 1-p- q> 1-x-y, for example, the active layer 7 made of p = 0) is grown to a thickness of about 0.02 to 0.1 [mu] m, further p-type Al _x Ga _y In _The p-type cladding layer 8 made of _1-xy N was grown to a thickness of about 0.1 to 2 μm. Al _r Ga _s In _1-rs N (0 ≦ r <1, 0 <s
≦ 1, 0 <r + s ≦ 1, r ≦ x)
Is provided with a thickness of about 0.2 to 2 μm.

In the above structure, both cladding layers 6 and 8 are formed to have the same composition, and these layers are formed to have a bandgap energy larger than that of the active layer 7. That is, by increasing the amount of Al and decreasing the amount of In, a material having a large band gap energy can be obtained, and the cladding layers 6 and 8 made of a material having a large band gap energy are made of a material having a small band gap energy. It has a structure in which the active layer 7 is sandwiched, and the carriers injected into the active layer are confined by an energy barrier to enhance the luminous efficiency.

After that, as described above, the electron beam irradiation is applied to p.
By lowering the resistance of the mold layer and forming an electrode and cleaving, a double heterojunction blue LED having a brightness of 0.5 candela (cd) was obtained.

According to this embodiment, since the active layer made of a material having a small band gap energy has a double heterojunction structure having a sandwich structure, it is possible to improve the light emission efficiency and to increase the thickness of a thick semiconductor such as a clad layer or a buffer layer. The layers are made of materials of the same composition, and the semiconductor layers of different compositions are formed so thin that crystal defects do not occur, so that it is possible to obtain a semiconductor layer with excellent film quality without defects and to facilitate cleavage. Become.

Example 2 This example is an example of a semiconductor laser, and as shown in the sectional explanatory view of FIG. 3, formation is performed in exactly the same manner as in Example 1 up to formation of each layer and formation of electrodes, and electrode formation. Later upper electrode 1
The upper portions of the cap layer 9 and the p-type clad layer 8 on both sides of 1 are etched into a mesa shape. With such a structure, the current can be concentrated only in the central portion of the active layer, and since the end surface is a mirror surface due to the cleavage, it can be reflected by the end surface and oscillate, and the output is 0. A 2 mW blue semiconductor laser was obtained.

Embodiment 3 This embodiment is an embodiment of a pn-junction LED, and is selected from GaAs substrate, InAs substrate, GaP substrate, InP substrate and the like as shown in the sectional view of FIG. A low temperature buffer layer 4 made of n-type GaN is formed on the III-V compound semiconductor substrate 3 in an amount of about 0.01 to 0.2 μm and an n-type G
The high temperature buffer layer 5 made of aN was grown under the same conditions as in Example 1 to a thickness of about 2 to 5 μm, and then n-type Al was formed.
_The n-type layer 12 made of _t Ga _1-t N (0 ≦ t <1) is set to 0.
About _{1 to 1} μm, p-type In _u Ga _1-u N (0 ≦ u <1)
A p-type layer (active layer) 13 composed of about 0.1 to 1 μm,
Each is formed into a film, and then p-type Al _z Ga _1-z N (0 ≦ z
The cap layer 14 made of <1) is formed, the p-type layer 13 is irradiated with an electron beam at an accelerating voltage of 3 to 20 kV, and annealed, and then the lower (n-side) electrode 11 and the upper (p-side) electrode 11 are formed.
The electrode 10 was formed to manufacture a heterojunction pn junction LED. With this heterojunction structure, the luminous efficiency was higher than that of a homojunction pn junction LED, and a blue LED with a brightness of 0.2 candela (cd) was obtained.

[0050]

According to the present invention, since the substrate is not an insulating substrate, the lower electrode may be formed on the back surface of the substrate, and the lower conductive type layer is exposed by etching from the upper surface as in the conventional case. It is not necessary to form an electrode. Therefore, the dry etching step is not required, the structure process is simplified, and the characteristic deterioration due to the resistance due to the contamination that tends to occur during etching does not occur.

As a characteristic of the substrate material, gallium arsenide is
The structure containing gallium in the buffer layer, indium arsenide,
The structure containing indium in the buffer layer, gallium phosphide,
A light emitting device having a wavelength of 550 nm or more, or a structure containing gallium in the buffer layer, and indium phosphide are semiconductor light emitting devices having a structure containing indium in the buffer layer, and a light emitting device having excellent characteristics can be obtained.

Since the compound semiconductor crystal serving as the substrate has a close lattice constant and the like, it is easy to match, and crystal defects and dislocations can be prevented from occurring. As a result, the quality of the semiconductor layer is improved, and the luminous efficiency and life of the device are improved. Further, since the same kind of crystals as the thick layer such as the clad layer are aligned, the cleavage can be easily performed and the mirror surface can be easily obtained. As a result, a blue semiconductor laser can be easily obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a semiconductor light emitting device of the present invention according to a manufacturing process.

FIG. 2 is an explanatory cross-sectional view of an LED of an embodiment of the semiconductor light emitting device of the present invention.

FIG. 3 is a cross-sectional explanatory view of a semiconductor laser of another embodiment of the semiconductor light emitting device of the present invention.

FIG. 4 is a sectional explanatory view of an LED of still another embodiment of the semiconductor light emitting device of the present invention.

FIG. 5 is a cross-sectional explanatory view of a conventional GaN-based LED.

FIG. 6 is a diagram illustrating a state of dislocations that occur in a buffer layer formed on a conventional sapphire substrate.

[Explanation of symbols]

 3 substrate 4 low temperature buffer layer 5 high temperature buffer layer 6 n-type clad layer 7 active layer 8 p-type clad layer 12 n-type layer 13 p-type layer

Claims (13)

[Claims] 1. A semiconductor light emitting device having a gallium nitride based compound semiconductor layer laminated on a III-V group compound semiconductor substrate as a constituent element. 2. The gallium nitride-based compound semiconductor layer is laminated on a substrate whose main surface is a surface of the III-V compound semiconductor having a group V atom as an outermost surface. Semiconductor light emitting device. 3. The semiconductor light emitting device according to claim 1, wherein the III-V compound semiconductor substrate is gallium arsenide. 4. The semiconductor light emitting device according to claim 1, wherein the III-V compound semiconductor substrate is indium arsenide. 5. The semiconductor light emitting device according to claim 1, wherein the III-V compound semiconductor substrate is gallium phosphide. 6. The semiconductor light emitting device according to claim 1, wherein the III-V compound semiconductor substrate is indium phosphide. 7. The gallium nitride-based compound semiconductor layer is a plurality of layers including a p-type layer and an n-type layer, and
6. An active layer for light emission, claim 1, 2, 3, 4, 5.
Alternatively, the semiconductor light emitting device according to the item 6. 8. The gallium nitride-based compound semiconductor layer comprises a buffer layer, a lower clad layer, an active layer, an upper clad layer, and a cap layer.
6. The semiconductor light emitting device according to 6 or 7. 9. The buffer layer is n-type Ga _z In _{1 -z} N
(0 <z ≦ 1), the lower cladding layer is n-type Al _x Ga
_1-x N (0 <x <1), the active layer is Ga _y In _1-y N
(0 <y ≦ 1), the upper cladding layer is p-type Al _x Ga
The semiconductor light emitting device according to claim 8, wherein the cap layer is _1-xN (0 <x <1), and the cap layer is p-type GaN. 10. A step of preparing a III-V group compound semiconductor substrate, a step of laminating a gallium nitride based compound semiconductor buffer layer on the main surface of the III-V group compound semiconductor substrate, and a nitride layer on the buffer layer. A step of sequentially laminating a lower clad layer, an active layer, an upper clad layer and a cap layer made of a gallium compound semiconductor with matching crystal lattices, and forming electrodes on the cap layer and the back surface of the III-V compound semiconductor substrate. And a step of cleaving a chip for each element, to manufacture a semiconductor light emitting element. 11. The method for manufacturing a semiconductor light emitting device according to claim 10, wherein the step of stacking the buffer layer includes a step of forming a low temperature buffer layer at a low temperature and a step of subsequently forming a high temperature buffer layer at a high temperature. . 12. The buffer layer is n-type Ga _z In _{1 -z}
N (0 <z ≦ 1), the lower cladding layer is n-type Al _x G
a _1-x N (0 ≦ x <1), the active layer is Ga _y In _1-y
N (0 <y ≦ 1), the upper cladding layer is p-type Al _x G
a _1-x N (0 ≦ x <1), and the cap layer is p-type GaN
The method for producing a semiconductor light emitting device according to claim 10 or 11, wherein 13. The III-V compound semiconductor substrate is V
The method for producing a semiconductor light-emitting device according to claim 8, 9 or 10, wherein a surface having a group atom as an outermost surface is prepared as a main surface.