JPH11220173A - Gallium nitride compound semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the performance of a nitride semiconductor light emitting element by putting a light emitting element in double hetero structure which has, between a substrate and an active layer, an n-type gallium nitride compound semiconductor layer having such structure that a second nitride semiconductor layer including one kind among Ina Ga1-a N, Aln Ga1-b N (a and b are specified values), etc., is put between first and third nitride semiconductor layers. SOLUTION: Putting a second nitride semiconductor layer different in composition in an n-type nitride semiconductor layer will let the second nitride semiconductor layer (buffer layer) works as a buffer layer, which can lighten a crystal defect. It is to be desired that this second buffer layer 33 should be a multilayer film where films of InIGa1-a N (0<a<=1) or Alb Ga1-b N (0<b<=1) or Alb Ga1-b N (0<a<=1) different in composition are stacked. Furthermore, for the most desirable combination, the n-type nitride semiconductor layers 3' and 3" are n-type GaN, and the second buffer layer 33 is n-type Ina Ga1-a N (0<a<=0.5) or n-type Alb Ga1-b N (0<b<=0.5), or the like. Accordingly, an excellent light emitting element little in crystal defects can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting diode, n-type gallium nitride compound is used in an electronic device such as a laser diode semiconductor _{(In X Al Y Ga 1-} XY N, 0 ≦ X,
0 ≦ Y, X + Y ≦ 1, hereinafter, a gallium nitride-based compound semiconductor is referred to as a nitride semiconductor. The present invention relates to a gallium nitride-based compound semiconductor light emitting device using the crystal of the above).

[0002]

2. Description of the Related Art Laser diodes emitting blue and ultraviolet light and nitride semiconductors (In _{X '}
Al _{Y ′} Ga _{1−X′−Y ′} N, 0 ≦ X ′, 0 ≦ Y ′, X ′ + Y ′ ≦ 1)
Recently, a blue light emitting diode with a luminous intensity of 1 cd has just been put to practical use with this material. As shown in FIG. 1, the blue light emitting diode has a buffer layer 2 made of GaN and a Ga layer on a surface of a substrate 1 made of sapphire.
An n-type layer 3 of N, an n-type cladding layer 4 of AlGaN, an active layer 5 of InGaN,
And a p-type contact layer 7 made of GaN.

[0003] A nitride semiconductor device is generally a MOVPE.
(Organic metal vapor phase epitaxy) method, MBE (molecular beam
(Pitaxial) method, HDVPE (hydride vapor phase epitaxy)
Nitridation on the substrate surface using vapor phase growth method such as
It is obtained by laminating an object semiconductor layer. On the board
Sapphire, ZnO, SiC, GaAs, MgO, etc.
Fees are used. N is provided on the surface of the substrate via a buffer layer.
Type nitride semiconductor (In _XAl_YGa_1-XYN, 0 ≦ X, 0
≦ Y, X + Y ≦ 1, among which n-type GaN and n-type Al
Mostly GaN. ) Will be grown. Also, SiC, ZnO
When using a substrate with a lattice constant close to that of a nitride semiconductor as in
In this case, the buffer layer is not formed, and the n-type nitride
Semiconductors may be grown. Basically, the board table
By first growing an n-type nitride semiconductor layer on the surface,
Nitride semiconductor devices such as light-emitting devices and light-receiving devices are manufactured.
You.

For example, according to the MOVPE method, as a nitride semiconductor, an organic metal compound gas serving as a Ga source, an Al source, and an In source and an ammonia gas serving as an N source are used as source gases. By bringing these source gases into contact with the heated substrate surface, the source gases are decomposed, and a nitride semiconductor is epitaxially grown on the substrate. Normally G
aN, AlN, GaAlN, etc. are selected,
It is grown at a temperature of 00 ° C. with a thickness of 10 Å to 0.1 μm. The n-type nitride semiconductor layer grown on the buffer layer is usually at least 1 μm at a temperature of 900 ° C. or more.
It is grown with a thickness of less than μm.

[0005]

It is known that a nitride semiconductor is a crystal that is very difficult to grow epitaxially because there is no substrate that is perfectly lattice-matched. Therefore, conventionally, a substrate close to the lattice constant of the nitride semiconductor to be grown, such as a SiC substrate, has been used, or epitaxial growth has been forcibly performed via a buffer layer that reduces lattice mismatch.

FIG. 2 shows, as an example, a schematic cross-sectional view of an n-type nitride semiconductor crystal grown on the surface of a substrate that does not have lattice matching. This is the Journal of Crystal Growth, 115, (1991) P628−63.
3), n-type GaN is epitaxially grown on the surface of a sapphire substrate via a buffer layer made of AlN, and its cross section is TEM (transmission e).
(electron microscopy) and schematically shows the crystal structure from the TEM image. According to this figure, a buffer layer with poor orientation is grown on the substrate in a columnar shape, and when GaN is epitaxially grown on the buffer layer, a part of the buffer layer plays a role like a seed crystal. This shows that the GaN layer with improved crystallinity is grown by gradually adjusting the orientation of GaN.

However, Ga which is completely free from crystal defects
It is difficult to grow N, and many crystal defects as shown by broken lines in FIG. 2 extend from the interface between the buffer layer and the GaN layer until reaching the GaN layer surface. Some of these defects stop inside the crystal, but those reaching the surface of the GaN layer are, for example, 10 ⁷ to 10 ⁹ / cm ^{2 at} the surface. Similarly, in the light emitting diode element of FIG. 1, the same phenomenon occurs in the crystal of the n-type layer 3.

When a large number of crystal defects are present on the surface of the n-type nitride semiconductor layer grown on the surface of the substrate, the defects are inherited by all the semiconductor layers such as the cladding layer and active layer growing on the surface of the n-type layer. This has the problem of adversely affecting the entire element structure. An element having a large number of crystal defects has a disadvantage that, for example, when the above-described light emitting diode is used, the element performance such as light emission output and life is adversely affected.

In growing an n-type nitride semiconductor layer on the surface of a substrate, it is very important to grow an n-type crystal having few crystal defects. Since the number of crystal defects in the clad layer, active layer, and the like is reduced, the performance of any device made of a nitride semiconductor can be improved. Accordingly, the present invention has been made in view of such circumstances, and the MOV
When growing an n-type nitride semiconductor layer on the surface of a substrate that is not completely lattice-matched by a vapor phase growth method such as PE or MBE, the growth is performed by reducing lattice defects in the n-type nitride semiconductor layer. It is an object of the present invention to provide a light emitting device using the n-type nitride semiconductor.

[0010]

SUMMARY OF THE INVENTION The present invention provides an In _a Ga _1-a
N (0 <a ≦ 1) or Al _b Ga _1-b N (0 <b ≦
1) or Al _b Ga _1-b N having a different composition (0 ≦ b ≦
The second n-type gallium nitride-based compound semiconductor layer including any one of the multilayer films obtained by laminating the thin films of 1) is formed by combining the first n-type gallium nitride-based compound semiconductor layer with the third n-type gallium nitride-based compound semiconductor layer. A gallium nitride-based compound semiconductor light emitting device having a double hetero structure in which an n-type gallium nitride-based compound semiconductor having a structure sandwiched between gallium-based compound semiconductor layers is provided between a substrate and an active layer.

The light emitting device according to claim 2 is characterized in that the active layer is made of InGaN, and wherein the first gallium nitride compound semiconductor layer and the third gallium nitride compound semiconductor layer are made of InGaN. Have the same composition.

[0012]

In the n-type nitride semiconductor layer, a second composition having a different composition is contained.
Is formed, it is considered that the second nitride semiconductor acts as a buffer layer, that is, a buffer layer, so that crystal defects can be reduced in the buffer layer (hereinafter, in this specification, the second nitride semiconductor The semiconductor layer is called a second buffer layer). More specifically, when an n-type nitride semiconductor layer is grown on a substrate, a mismatch between the substrate and the nitride semiconductor is large, so that a crystal defect as shown by a broken line in FIG. 2 occurs in the crystal during the growth. . However, by interposing, as an intermediate layer, a second buffer layer having a different composition from the n-type nitride semiconductor layer to be grown, continuous crystal defects of the n-type nitride semiconductor layer cause the second buffer layer having a different composition. Stops temporarily in the buffer layer. Next, when the n-type nitride semiconductor is grown on the surface of the second buffer layer, the n-type nitride semiconductor acts like a substrate having a small mismatch, and is grown on the second buffer layer. It is presumed that the crystallinity of the n-type nitride semiconductor is improved.

The second buffer layer may be formed in one or more layers, and the thickness of one layer is in the range of 10 Å (0.001 μm) or more and 1 μm or less, and more preferably 0.001 μm or more and 0.1 μm or less. It is desirable to adjust. If the thickness is smaller than 0.001 μm, it tends to be difficult to stop crystal defects in the second buffer layer. If the thickness is larger than 1 μm, new crystal defects tend to be easily generated from the second buffer layer. The second buffer layer may have a thickness of several tens angstroms, and may be a multilayer film in which two or more layers are stacked.

The second buffer layer is composed of In _a Ga _1-a N (0 <
a ≦ 1), Al _b Ga _1-b N (0 <b ≦ 1), or a multilayer film in which thin films of Al _b Ga _1-b N (0 ≦ b ≦ 1) having different compositions are stacked. desirable. More preferably, In _a Ga _1-a N having an _a value of 0.5 or less or Al _b Ga _1-b N having a b value of 0.5 or less is grown. Because
In a nitride semiconductor, the ternary mixed crystal has better crystallinity than the quaternary semiconductor layer. In _a Ga _1-a N ternary mixed crystal Among them, the _{Al b Ga 1-b N,} a value, and the buffer layer a b value was adjusted to the range further for good crystallinity is obtained In addition, crystal defects of the second buffer layer are reduced, and crystal defects of the n-type nitride semiconductor layer grown on the second buffer layer are reduced. further,
When the second buffer layer is a multilayer film, crystal defects can be stopped very well. The most preferred combination is n
N-type GaN (GaN has the fewest lattice defects), and the second buffer layer is n-type In _a Ga _1-a N
(0 <a ≦ 0.5) or n-type Al _b Ga _1-b N
(0 <b ≦ 0.5) or Al _b Ga having a different composition
_1-b N (0 ≦ b ≦ 1) multilayer film (superlattice)
It is.

Further, the electron carrier concentration of the second buffer layer is substantially the same as that of the previously formed n-type nitride semiconductor layer.
Or it is desirable to adjust larger. FIGS. 3 and 4 show that an n-cladding layer 4 ', an active layer 5', a p-cladding layer 6 ', and a p-contact layer 7' are laminated on the n-type nitride semiconductor layer 3 "obtained by the method of the present invention. 3 is a cross-sectional view showing the structure of the light emitting device as an actual light emitting device, wherein the second buffer layer 33 is more active than the etched surface of the n-type layer for forming the negative electrode. 4 differs from the layer 5 'in that the second buffer layer 33 is formed closer to the substrate 1' than the etched surface.For example, a light emitting device as shown in FIG. In other words, when an element is realized in which the position of the second buffer layer 33 is closer to the active layer side than the etching surface on which the negative electrode is to be formed, the electron carrier concentration of the second buffer layer 33 is Is smaller than the n-type layer 3 ′, n is supplied from n to p in the second buffer layer. Electrons are blocked and p-type
Current hardly flows through the layer, and the performance of the device deteriorates. Conversely, if the electron carrier concentration of the second buffer layer 33 is higher than that of the n-type layer 3, electrons are likely to spread uniformly in the second buffer layer 33, so that uniform light emission can be obtained. On the other hand, in the device as shown in FIG. 4, even if the electron carrier concentration of the second buffer layer 33 is low, the current flows through the n-type layer 3 ″ having a high electron carrier concentration. Has almost no effect, but conversely, if the electron carrier concentration of the second buffer layer 33 is high, the current tends to flow toward the second buffer layer 33, and uniform light emission is obtained. The electron carrier concentration of the second buffer layer 33 is preferably adjusted to be substantially the same as or higher than that of the n-type nitride semiconductor layer formed earlier.

By growing the n-type nitride semiconductor layer thicker than 5 μm, crystal defects reaching the surface can be reduced. In FIG. 2, the broken line stops in the middle of the n-type layer, indicating that the crystal defect stops in the middle. When the crystal defects stopped on the way were studied in more detail, it was newly found that many of the n-type nitride semiconductor layers stopped at about 4 μm from the substrate. Therefore, if the same material is continuously grown, it is possible to gradually stop the crystal defects during the growth. Therefore, by growing the n-layer at 5 μm or more, the crystal defects reaching the surface of the n-layer can be obtained. Can be reduced. More preferably, the thickness of the n-type nitride semiconductor layer is 7 μm or more.

In the present invention, the substrate is grown on a substrate.
n-type nitride semiconductor (In_XAl_YGa _1-XYN, 0 ≦ X, 0
≦ Y, X + Y ≦ 1) means that the Y value is in the range of 0 ≦ Y ≦ 0.5._Y
Ga _1-YN, more preferably Al not more than 0.3_YGa
_1-YGrow N, most preferably Y = 0 GaN. What
In other words, as described above, a quaternary mixed crystal nitride semiconductor
The original mixed crystal nitride semiconductor has fewer crystal defects.
You. In addition, electronic devices such as light emitting elements and light receiving elements
When using an n-type nitride semiconductor, the
The n-type nitride semiconductor to be elongated has a small band gap.
AlGaN having a larger band gap than InGaN,
GaN has various structures such as single hetero and double hetero.
This is because it is convenient for realizing the structure. inside that
However, in particular, AlGaN has crystal defects that contain Al.
GaN tends to increase and n
Type nitride semiconductor layers tend to grow.

The substrate is sapphire, GaAs, Si, Z
Although materials such as nO and SiC can be used, sapphire is generally used. When sapphire is used as a substrate, it is preferable to grow a buffer layer on the substrate. However, depending on the plane orientation of the sapphire substrate, growth can be performed without a buffer layer. By preferably growing the buffer layer, it is possible to obtain a smooth and mirror-like n-type nitride semiconductor crystal capable of measuring lattice defects. Further, in order to make the nitride semiconductor n-type, a non-doped state or S
This can be realized by doping a donor impurity such as i, Ge, and C during crystal growth.

[0019]

The method of the present invention by the MOVPE method will be described in detail below. [Example 1] First, a well-washed sapphire substrate is placed on a susceptor in a reaction vessel. After evacuating the container,
While flowing hydrogen gas into the container, the substrate is heated at 1050 ° C. for about 20 minutes to remove oxides on the surface, and the substrate is cleaned. Thereafter, the temperature of the susceptor was adjusted to 500 ° C., and at 500 ° C., TMG (trimethyl gallium gas) as a Ga source and ammonia gas as an N source were flowed over the surface of the substrate, and the buffer layer made of GaN was placed at 0.0 ° C.
It is grown to a thickness of 2 μm.

Next, the TMG gas is stopped and the temperature is set to 10
After the temperature is raised to 50 ° C., TMG gas and SiH ₄ gas are flowed to grow a Si-doped n-type GaN layer to a thickness of 2 μm.

Next, the TMG gas and the SiH ₄ gas are stopped and the temperature is set to 800 ° C. When the temperature reaches 800 ° C., the carrier gas is switched to nitrogen, TMG gas, TMI (trimethylindium), and SiH ₄ gas are flown, and a Si-doped n-type In0.1Ga0.9N layer is formed as a second buffer layer by 0.01.
It is grown to a thickness of μm.

After the growth of the In0.1Ga0.9N layer, the temperature is increased again to 1050 ° C., the carrier gas is returned to hydrogen, and the TMG gas and the SiH ₄ gas are flown.
An i-doped n-type GaN layer is grown to a thickness of 2 μm. Note that the carrier concentration of the second buffer layer and the carrier concentration of this n-type GaN layer were almost the same.

After the growth, the substrate is taken out of the reactor, the surface of the uppermost n-type GaN layer is measured by TEM, and its TE is measured.
When the number of crystal defects per unit area was measured from the M image, it was about 1 × 10 ⁴ / cm ² .

In Example 2 and the step of forming the n-type nitride semiconductor layer, TMG, TMA (trimethylaluminum) and SiH ₄ gas were used, and the Si-doped n-type Al
The procedure is the same as that of the first embodiment, except that a 0.3Ga0.7N layer is grown to a thickness of 2 μm to sandwich the second buffer layer. As a result, the number of crystal defects reaching the surface of the Si-doped n-type Al0.3Ga0.7N layer was about 5 × 10 ⁵ / cm ² , as measured in the same manner. The electron carrier concentration of the Si-doped n-type Al0.3Ga0.7N layer is the second
Of the buffer layer.

A Si-doped n-type GaN layer is grown to a thickness of 1 μm in the same manner as in the step of forming the n-type nitride semiconductor layer in [Example 3]. Next, as in the step of the second buffer layer, a Si-doped n-type In0.
A 1 Ga 0.9 N layer is grown to a thickness of 50 Å. Further, similarly to the process of the n-type nitride semiconductor layer, a Si-doped n-type GaN layer is sequentially grown to a thickness of 1 μm.

Further, in the same manner as in the step on the Si-doped n-type GaN layer, a Si-doped n-type In0.1Ga0.9N layer is grown once more as a third buffer layer to a thickness of 50 angstroms. As in the last step, a Si-doped GaN layer is grown to a thickness of 2 μm. That is, in Example 3, the GaN buffer layer 200 Å, the n-type GaN layer 1 μm,
An Si-doped n-type In0.1Ga0.9N second buffer layer 50 Å, an n-type GaN layer 1 μm, a Si-doped n-type In0.1Ga0.9N third buffer layer 50 Å, and an n-type GaN layer 2 μm were sequentially stacked.

As a result, the final layer of Si-doped n-type GaN
The number of crystal defects reaching the surface of the layer is approximately 1 × 10 ⁴
Pieces / cm ² . The electron carrier concentrations of the second buffer layer, the third buffer layer, and the Si-doped n-type GaN layer were almost the same.

In a step of the second buffer layer of Example 4], TMG without changing the growth temperature, TMA (trimethyl aluminum), using the SiH ₄ gas, a Si-doped n-type Al0.3Ga0.7N layer 0 The process is performed in the same manner as in the first embodiment, except that the second buffer layer is formed by growing at a thickness of 0.01 μm. As a result, when measured in the same manner, Si
The number of crystal defects reaching the surface of the doped n-type GaN layer was about 1 × 10 ⁴ / cm ² . Note that the electron carrier concentration of the second buffer layer was almost the same as that of the Si-doped n-type GaN layer.

In the step of forming the second buffer layer in the fifth embodiment, TMG, TMA, Si
Using H ₄ gas, first, Si-doped n-type Al0.02Ga0.98
An N layer is grown to a thickness of 30 Å. Next, the TMA gas is stopped, and a Si-doped n-type GaN layer is grown to a thickness of 30 Å. This operation is repeated five times to form a multilayer film in which 30 angstrom Si-doped n-type Al0.02Ga0.98N layers and 30 angstrom n-type GaN layers are alternately laminated by five layers. Except for forming the second buffer layer as described above, the same operation as in the first embodiment is performed. As a result, when the lattice defect was measured in the same manner, the Si-doped n-type G
The number of crystal defects reaching the surface of the aN layer is about 5 × 10
^{It was 3} pieces / cm ² . Note that the electron carrier concentration of the multilayer film as the second buffer layer was substantially the same as that of the Si-doped n-type GaN layer.

[Embodiment 6] In the process of Embodiment 2, Si-doped n-type Al0.1GaGa was used as the second buffer layer.
A Si-doped n-type Al0.3Ga0.7N layer was grown in the same manner except that 0.9N was grown to a thickness of 0.01 μm.
As a result, the number of lattice defects reaching the outermost n-type Al0.3Ga0.7N layer was about 1 × 10 ⁵ / cm 2. The electron carrier concentration in this example was also substantially the same.

[Comparative Example 1] In Example 1, the second buffer layer was not grown and Si-doped n-type GaN was continuously formed.
When the layer was grown to a thickness of 4 μm, the number of crystal defects reaching the surface of the n-type GaN layer was about 1 × 10 ⁷ / cm ² .

[Embodiment 7] An embodiment in which the structure of an actual light emitting element is used will be described. The following steps were added after the steps of Example 1. After the growth of the Si-doped n-type GaN layer, a new TMA (trimethylaluminum) gas is
Then, as an n-cladding layer, Si-doped n-type Al0.2 Ga0.8
An N layer is grown to a thickness of 0.1 μm.

After growing the n-cladding layer, TMG, TM
A, the SiH ₄ gas was stopped, the temperature was set again to 800 ° C., and in addition to TMG, TMI, and SiH ₄ gas, DEZ (diethyl zinc) was flown, and an Si and Zn-doped In0.05Ga0.95N layer was formed as an active layer. It is grown to a thickness of 0.1 μm.

After growing the active layer, TMG, TMI, Si
After stopping H ₄ and DEZ gas and setting the temperature to 1050 ° C.,
TMG, TMA, and Cp2Mg (cyclopentadienylmagnesium) gas are flowed, and a Mg-doped p-type Al0.1Ga0.9N layer is grown as a p-cladding layer to a thickness of 0.1 .mu.m.

After growing the p-type Al0.1Ga0.9N layer, the TM
The A gas is stopped, and a Mg-doped p-type GaN layer is grown at 1050 ° C. as a p-contact layer with a thickness of 0.3 μm.

The device obtained as described above is etched, and the n-type GaN grown next to the second buffer layer is etched.
The layer was exposed, and electrodes were formed on the p-contact layer and the exposed Si-doped n-type GaN layer. That is, a light emitting diode element having a structure as shown in FIG. 4 was obtained. The device was mounted on a lead frame and molded with resin. This light-emitting diode had a Vf of 3.6 V, an emission wavelength of 450 nm, a luminous intensity of 3.0 cd, and an emission output of 3.5 mW at 20 mA.

Comparative Example 2 The same process as in Example 7 was performed on the Si-doped GaN layer grown in Comparative Example 1 to obtain a light emitting diode device having a structure as shown in FIG. The diode has a Vf of 3.6 at 20 mA.
V, the emission wavelength was 450 nm, but the luminous intensity was 1.0 cd.
And the light emission output was only 1.2 mW.

As described above, since the light emitting device of the present invention has the n-type layer with few crystal defects, the crystal defects such as the cladding layer and the active layer laminated thereon are reduced. In particular, since the thickness of the active layer is as thin as about 0.2 μm or less, it is very important to grow a crystal having few crystal defects. Therefore, since a crystal having few crystal defects can be grown, it is possible to realize a light-emitting diode element having a luminous intensity of 1 cd or more and excellent in light-emission output as in the related art.

[Embodiment 8] A buffer layer made of GaN is grown to a thickness of 0.02 μm on the surface of a sapphire substrate in the same manner as in the process of Embodiment 1.

In the same manner as in the first embodiment, a Si-doped n-type GaN layer is grown to a thickness of 10 μm on the buffer layer.

After the growth, the substrate is taken out of the reaction vessel and n
GaN layer surface is measured by TEM, and from the TEM image,
When the number of crystal defects per unit area was measured, it was about 1 × 10 ⁵ / cm ² .

Example 9 Crystal growth was performed in the same manner as in Example 5 except that the thickness of the Si-doped n-type GaN layer was changed to 5 μm, and the number of crystal defects on the surface of the n-type GaN layer was about 5 × 10 ⁶ pieces.

[Embodiment 10] In the process of Embodiment 5, the Si-doped n-type Al 0.3
Crystal growth was performed in the same manner except that a Ga0.7N layer was continuously grown to a thickness of 10 μm.
The number of crystal defects on the a0.7N layer surface is approximately 3 × 10 ⁶ /
It was cm ^2.

[Embodiment 11] An n-cladding layer, an active layer, a p-cladding layer and a p-contact layer were laminated on the Si-doped GaN layer obtained in the embodiment 5 in the same manner as in the embodiment 7, and As a result, the characteristics were almost the same as those of Example 7.

[0045]

As described above, the light emitting device of the present invention has the n-type nitride semiconductor layer with few crystal defects on the substrate. Therefore, the present invention is very useful because it can be applied to an electronic device such as a light-receiving element, because the nitride semiconductor light-emitting element having no lattice-matching substrate has crystals with few crystal defects stacked thereon.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one structure of a conventional light emitting diode element.

FIG. 2 is a schematic cross-sectional view showing a crystal structure when an n-type GaN layer is grown on a surface of a substrate via an AlN buffer layer.

FIG. 3 is a schematic cross-sectional view showing one structure of a light emitting diode device having an n-type nitride semiconductor layer of the present invention.

FIG. 4 is a schematic cross-sectional view showing one structure of a light emitting diode device having an n-type nitride semiconductor layer of the present invention.

[Explanation of symbols]

1, 1 '... substrate 2, 2'
..Buffer layers 3,3 ', 3 "... N-type nitride semiconductor layers 4,4'.
..N-type cladding layers 5, 5 '... Active layers 6, 6'
..P cladding layer 7, 7 '... p contact layer 33 ... second buffer layer (second nitride semiconductor layer)

Claims (3)

[Claims] 1. A _{In a Ga 1-a N (} 0 <a ≦ 1), or _{Al b Ga 1-b N (} 0 <b ≦ 1), or a different Al _b Ga _1-b N compositions (0 ≦ b ≦ 1), a second n-type gallium nitride-based compound semiconductor layer including any one of the multilayer films laminated with the first n-type gallium nitride-based compound semiconductor layer and a third n-type gallium nitride-based compound semiconductor layer A gallium nitride-based compound semiconductor light-emitting device having a double hetero structure, comprising an n-type gallium nitride-based compound semiconductor having a structure sandwiched between n-type gallium nitride-based compound semiconductor layers between a substrate and an active layer. 2. The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein said active layer is made of InGaN. 3. The growth of a gallium nitride-based compound semiconductor according to claim 1, wherein the first gallium nitride-based compound semiconductor layer and the third gallium nitride-based compound semiconductor layer have the same composition. Method.