JPH11121806A - Semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a light emitting device for emitting light of all wavelength bands in all arrange of visible light, by providing two or more luminescent layers having different wavelengths near to both of a p-type layer and an n-type layer. SOLUTION: An n-type current passing layer 202 comprising a GaN film, which is doped with Si of 5×10<19> atom/cm and has a thickness of about 4 μm, is formed on a sapphire substrate 201. Then, luminescent layers 203, 204, 205 (red. green, blue) are formed, each of which comprises In0.9 Ga0.1 N, In0.4 Ga0.6 N,-In0.2 Ga0.8 N, respectively and has a thickness of about 3 nm. The luminescent layers 203, 204, 205 are sandwiched by barrier layers 206 comprising In0.05 Ga0.95 N (-thickness: about 10 μm). A p-type current passing layer 207 comprising a GaN film, which is doped with Mg of 5×10<19> atom/cm and has a thickness of about 0.5 μm and, is formed on the barrier layers 206. This can produce a light emitting device for emitting light of all wavelength bands in all range of visible light.

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 semiconductor light emitting device having two or more light emitting layers of a semiconductor light emitting device and having two or more emission wavelengths.

[0002]

2. Description of the Related Art Conventionally, it is not uncommon to manufacture a light emitting device using a compound semiconductor. For example, taking a nitride semiconductor as an example, this semiconductor has a wide band gap of 2 eV or more, and is used as a light-emitting element material having a wide width from red to ultraviolet regions. Until now, these devices have been developed using an InGaN light-emitting layer as light-emitting devices having a single emission wavelength band such as blue or green.

Although a technique of producing a plurality of quantum well layers to emit light is also used, since the emission wavelength bands of the quantum wells are all the same (mostly because they form subbands). The emission wavelength is the same for all the layers.) Even in a device having a plurality of light-emitting layers, the emission wavelength of the device was intentionally aimed at one wavelength.

As light emitting elements having emission wavelengths of two or more colors, for example, a combination of LED light emission and photoluminescence light as disclosed in JP-A-8-288549, and a light-emitting element disclosed in JP-A-6-53549 are disclosed. In the same manner, between a plurality of electrodes, a large number of light emitting elements are stacked to form a multi-color light emitting element, a blue light emitting element is covered with a phosphor that emits yellow light, and two colors of blue and yellow are mixed, Light-emitting element that emits white light (for example, Nikkei Sangyo Shimbun, September 13, 1996)
Is being developed.

In addition, materials such as AlGaAs are often used as infrared or red light emitting elements.
As with the nitride semiconductors, these have been developed as light emitting elements having a single light emitting wavelength band as the light emitting layer.

[0006]

When the light emitting element is used as a light source of monochromatic light, it is desirable that the light emission wavelength is one. However, for example, when used as a light source having a wide emission wavelength band for use in a scanner, or when emitting white light used for illumination using a nitride semiconductor, a plurality of light emitting elements having different emission wavelengths To adjust the light to the required wavelength, or, as described above, adjust the light to the required wavelength by incorporating a light-emitting element with a short emission wavelength and a phosphor with a longer emission wavelength into the element. And so on.

Further, when laminating light emitting elements, it is necessary to connect a large number of electrodes. In this case, the element structure has a problem that the number of electrodes is increased and the emission control becomes complicated. In addition, when photoluminescence light is used as introduced in the related art, the photoluminescence light absorbs current injection light and emits light, so that the light emission efficiency of the light emitting element itself with respect to the injection current is reduced, and the photoluminescence is reduced. It was difficult to adjust the balance between light and current injection light. In addition, when a phosphor is coated with a nitride semiconductor to produce a white light-emitting element, it is necessary to perform a complicated process when molding a resin.

An object of the present invention is to solve the above-mentioned problems and to provide a semiconductor light emitting device which has a pair of electrodes in one light emitting device and generates light of a plurality of emission wavelengths.

[0009]

A semiconductor light emitting device according to the present invention (claim 1) is different from a semiconductor light emitting device formed between a pair of electrodes in the vicinity of both a p-type layer and an n-type layer. It is characterized by having two or more light emitting layers of wavelengths. Thus, the wavelength band of light emitted from the light emitting element becomes the sum of the wavelength bands emitted from the respective light emitting layers, and the above object is achieved.

The semiconductor light emitting device according to the present invention (claim 2) has a plurality of light emitting layers which emit light in parallel between a pair of electrodes as one means for forming light emitting layers having different wavelengths. It is characterized by doing. According to this structure, the above-described object is achieved because light of different wavelengths can be emitted without each light emitting layer interfering with each other to emit light.

The semiconductor light emitting device according to the present invention (claim 3) has a plurality of light emitting layers that emit light in series between a pair of electrodes as one means for forming light emitting layers of different wavelengths. It is characterized by doing. With this structure, the light-emitting element can be easily manufactured and can emit light of different wavelengths, so that the above object is achieved.

A semiconductor light emitting device according to the present invention (claim 4) is a nitride semiconductor light emitting device.

[0013] In a semiconductor light emitting device according to the present invention (claim 5), in the semiconductor light emitting device according to claim 3, the plurality of light emitting layers are nitride semiconductor light emitting layers containing In. The In composition ratio is different, and the In composition ratio of the light emitting layer located closest to the substrate is the largest, and the In composition ratio of the light emitting layer decreases in order as the distance from the substrate increases.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to the third aspect, the light emitting layer is a nitride semiconductor light emitting layer containing In, and the light emitting layer located closest to the substrate. It is characterized in that the luminosity of the emission wavelength of the layer is the lowest, and the luminosity of the emission wavelength of the luminescence layer becomes higher as the distance from the substrate increases.

In the semiconductor light emitting device according to the present invention (claim 7), in the semiconductor light emitting device according to claim 2, the plurality of light emitting layers are nitride semiconductor light emitting layers containing In. In composition ratios are different, the layers are formed in order from the inside to the outside in a plane parallel to the substrate, and the light emitting layer located outside is formed so as to surround the light emitting layer adjacent inside.

The operation of the present invention will be described below. In the present invention, a plurality of light emitting layers having different light emission wavelengths are provided between a pair of electrodes. When a voltage is applied between the pair of electrodes, current is injected into the light-emitting element, and light is generated by recombination of electrons and holes in each light-emitting layer. The intensity and wavelength of the generated light are controlled by the composition, thickness and resistance of the constituent light emitting layer and the composition and resistance of the surrounding current injection layer, and at an appropriate wavelength and intensity, an emission spectrum having a multi-wavelength emission peak. Occurs.

Since the emission wavelength from a light emitting element having a plurality of light emitting layers having different emission wavelengths is the sum of the emission wavelengths from the respective light emitting layers, the luminous efficiency of each light emitting layer is determined by the composition and thickness of the light emitting layer. By adjusting the type and amount of doping, and doping, light emission of a required color can be obtained.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a schematic view showing an example of a light emitting device manufactured according to the present invention. In the figure, 101 is a substrate for performing crystal growth, 103, 105, and 106 are light-emitting layers having different emission wavelengths, 102 and 107 are n-type current injection layers for injecting current, and p-type current injection, respectively. Layers, 1
Numeral 04 denotes a barrier layer for isolating the light emitting layers, and 10
Reference numerals 8 and 109 are a p-type ohmic electrode and an n-type ohmic electrode, respectively.

For example, taking a light emitting device composed of a nitride semiconductor as an example, the structure of the light emitting device can be manufactured by, for example, metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxial growth (MBE). Here, an example of manufacturing a GaN-based nitride semiconductor light-emitting element manufactured on a sapphire substrate by MOCVD is shown. Crystal growth can be performed, for example, by the following procedure.

First, the substrate 101 is placed in a hydrogen atmosphere for about 11 hours.
After cleaning at a temperature of 00 ° C. for about 10 minutes, the temperature was lowered to about 600 ° C., and ammonia (NH ₃ ) as a raw material,
A predetermined amount of trimethylgallium (TMG) is flown to form a buffer layer. Thereafter, the supply of TMG is stopped, the temperature is raised to about 1000 ° C., and TMG and a doping gas for controlling the carrier concentration are again supplied to supply the n-type current injection layer 102.
Is epitaxially grown to about 3 μm. Then, TMG
And the supply of the doping gas is stopped, and the temperature is set to about 800 ° C.
To TMG and trimethylindium (TM
I) is supplied in a predetermined amount, and the light-emitting layers 103, 105, and 106 and the barrier layer 104 are grown with a predetermined thickness and a predetermined composition. Thereafter, the supply of TMG and TMI is stopped again, the temperature is raised to about 1000 ° C., and TMG and a doping gas are supplied again to grow the p-type current injection layer 107.

In this growth example, the light-emitting element composed of the current injection layer made of GaN and the light-emitting layer made of InGaN has been described. However, the present invention is not limited to this layer structure, and any structure that emits light by injecting current may be used. . Further, the composition of each layer is not limited to those described above, and AlGaN, GaN, InGaN, InN,
What is necessary is just to be comprised with the semiconductor which has nitrogen as a main component, such as AlGaInN.

The multilayer film thus grown is partially etched to the current injection layer 102 by, for example, a dry etching method, and then an n-type ohmic electrode 109 and a p-type ohmic electrode 108 are formed by a vapor deposition method or the like. Then, by cutting into a predetermined shape, a GaN-based nitride semiconductor light emitting device can be manufactured.

(Embodiment 1) In this embodiment, a light emitting layer which emits light having different wavelengths in series is provided between a pair of electrodes.
An example in which a nitride semiconductor light emitting device having layers is manufactured will be described.

FIG. 2 is a sectional view of a light emitting device manufactured according to this embodiment. In the figure, 201 is a substrate made of sapphire, 202 is an n-type current injection layer made of a GaN film of about 4 μm doped with 5 × 10 ¹⁹ Si / cm,
204 and 205, respectively _{In 0. 9 Ga 0.1 N, In} 0.4 Ga
_The light-emitting layers are made of _0.6 N and In _0.2 Ga _0.8 N, each having a thickness of about 3 nm, 206 is a barrier layer made of In _0.05 Ga _0.95 N, the thickness of each light-emitting layer is about 10 nm, and 207 is M
g of about 0.5 μm doped with 5 × 10 ¹⁹ / cm
This is a p-type current injection layer made of an N film.

The p-type ohmic electrode 2 of the light emitting device of this structure
08, a current was injected between the n-type ohmic electrodes 209 to emit light, and spectral analysis revealed that the light was composed of three colors of red, green, and blue emitted from each light emitting layer (FIG. 5). This is because the three light emitting layers are separated by a thin 10 nm barrier layer, but the three light emitting layers diffuse minority carriers (electrons or holes) from both the n-type current injection layer 202 and the p-type current injection layer 207. Length: juxtaposed within 50 nm, resulting from injection of electrons and holes into each light emitting layer.

Further, by adjusting the thickness of each light-emitting layer of the light-emitting element or intentionally adding impurities, the intensity of green light with high visibility is reduced and the light emission of blue with low visibility is reduced. By increasing the intensity, a white light-emitting element could be manufactured.

According to this method, a light-emitting element having a light-emitting layer emitting a plurality of different wavelengths can be easily manufactured. In addition, it was also confirmed that a light-emitting element having a light-emitting layer other than three layers (two layers or four layers or more) similarly showed light emission characteristics at a plurality of light emission wavelength peaks.

Further, in the structure of the light emitting device of the above embodiment, the relationship between the In content of each of the light emitting layers 203, 204, and 205 and the position from the substrate was examined. Here, the substrate 20
1, the light emitting layer 203 is In _x Ga _{1 -x} N, the light emitting layer 204 is In _y Ga _{1 -y} N, and the light emitting layer 205 is In _z Ga 1.
_{When 1-zN} , x>y> z,
It showed the highest luminous efficiency with respect to the input power. this is,
The more the InGaN layer contains more In, the more the n-type current injection layer 2
02, the crystal distortion with the p-type current injection layer 207 is large, the crystallinity is deteriorated, and the luminous efficiency is easily lowered. This is thought to be due to the interaction that the crystallinity is deteriorated and the luminous efficiency is apt to be reduced (the later formed in the crystal growth step). That is, I
By forming the n _x Ga _1-x N most substrate 201 side light-emitting layer 203 made of, is due to be able to maintain a high emission efficiency from the light-emitting layer 203. This configuration is applicable not only to the case of a three-layer light emitting layer structure for forming a white light emitting element, but also to the case of having two or four or more light emitting layers,
Similar effects were confirmed not only in the case of the light emitting layer configuration corresponding to the blue and green colors, but also in the case of the combination of yellow green and blue.

On the other hand, when the device of this embodiment is used as a white lamp as described above, a light emitting layer corresponding to three colors of red, green and blue is required, but the light emitting layer 203 emits blue light. When the light-emitting layer 204 was a light-emitting layer emitting red light, and the light-emitting layer 205 was a light-emitting layer emitting green light, the luminous intensity was highest with respect to the input power. this is,
Of the three colors, the green light-emitting layer having the highest luminosity is the light-emitting layer 205 farthest from the substrate (to be formed later in the crystal growth step).
Then, by forming red with high visibility on the light emitting layer 204 and blue with the lowest visibility on the light emitting layer 203, the luminous efficiency, which decreases in the order closer to the substrate 201, can be compensated for by luminosity. This is a result of maintaining the balance of the emission intensities of the three colors required for white.

As a comparative example, the light emitting layer closest to the substrate 201 (the light emitting layer formed first in the crystal growth step) 2
In the case where 03 is a light emitting layer that emits green light having the highest luminosity among the three colors, the light emitting layer that emits red or blue light having a relatively low luminous efficiency is replaced with the light emitting layer 204 whose light emission efficiency is apt to decrease. The layer 205 must be formed on the layer 205, and it is not possible to realize the optimum three-color light emission intensity for obtaining white light (green light is too strong compared to red or blue). It is considered that the reason why the quality of the crystal is good and the luminous efficiency is high is that the damage of the luminous layer having low luminosity among the three colors is most reduced.

(Embodiment 2) In this embodiment, two light emitting layers each emitting light having a different wavelength are provided in parallel between a pair of electrodes.
An example of manufacturing a light-emitting element having a surface will be described.

FIG. 3A is a sectional view of a light emitting device manufactured according to this embodiment. First, 5 × of Si is placed on
10 ¹⁹ / cm doped 4μm thickness of the GaN film (n
Current injection layer 302) is grown, and a 3 nm thick In _0.4 G
a _0.6 N film (light-emitting layer 303), 1000 nm-thick Mg-doped GaN film (p-type current injection layer 304), 1
A GaN film (contact layer 305) having a thickness of 00 nm and heavily doped with Mg is sequentially grown. After that, the growth film is once taken out of the growth apparatus, and about half of the part to be an element is etched using a technique such as reactive ion etching (RIE). The mask used for the etching may be of any material, but if SiO ₂ is used, a step of forming a new mask at the time of regrowth can be omitted. In this embodiment, a mask of SiO ₂ is used. did. Etching, depth is 1 μm.

The etched growth film is transported again to the growth apparatus with the SiO ₂ mask attached, and Si is added to the growth film.
A GaN film (n-type current injection layer 306) doped with × 10 ¹⁹ / cm, an In _0.3 Ga _0.7 N film (light-emitting layer 307) with a thickness of 2.5 nm, and a Mg film with a thickness of 1000 nm of 5 × 10 ¹⁹ / cm
cm-doped GaN film (p-type current injection layer 30
8) A GaN film (contact layer 309) doped with 100 nm thick Mg at a concentration of 1 × 10 ²⁰ / cm is sequentially grown to a total thickness of 1 μm, taken out of the growth chamber again, and HF or the like. Is used to remove the SiO ₂ mask.

Thereafter, in order to form the n-type ohmic electrode 310, a part of the chip was again masked and etched by about 3 μm, and the n-type ohmic electrode 310 was masked on the etched surface. A p-type ohmic electrode 311 is formed on each of the portions (the portions over the contact layers 305 and 309) by an evaporation method. Both electrodes (n-type ohmic electrode 31) of the chip manufactured by the method described above
By applying a voltage to the 0, p-type ohmic electrode 311), light having a wavelength emitted from the two light emitting layers (303, 307) could be observed (FIG. 6).

FIG. 3B is a schematic view of a light-emitting device having three different types of light-emitting layers manufactured by the same method. In the figure, 351 is a substrate, 352 is an n-type current injection layer (GaN
353, 354 are the regrown n-type current injection layer, 3
Light emitting layers 56, 357, and 358 emit light at different wavelengths, and light emitting layers 359, 360, and 361 each include p-type Ga.
The N current injection layers 362 and 363 are electrodes, which are a p-type ohmic electrode and an n-type ohmic electrode, respectively. From this device, emission spectra of three different wavelengths could be confirmed.

FIG. 4 shows a light emitting element formed of three kinds of light emitting layers having the same composition and the same area as those of FIG.
A configuration example having a different shape will be described. In the figure, 376 is a p-type ohmic electrode, 370, 371 and 372 are light emitting regions, 373
Is a light emitting layer. The light emitting layer 373 includes light emitting regions 370, 3
373a, 37
3b and 373c (not shown). Also,
375 is an n-type ohmic electrode, 374 is an n-type current injection layer (GaN film), and 379 is a regrown n-type current injection layer. The n-type current injection layer 379 is not formed in a region corresponding to the light-emitting layer 373a, and the n-type current injection layer 374 is formed until it contacts the light-emitting layer 373a. The n-type current injection layer 379 corresponds to the light emitting layers 373b and 373c,
79b and 379c (not shown). 37
Reference numeral 7 denotes a p-type current injection layer (GaN film), on which 377a, 377b, and 377c are formed similarly to the light emitting layer 373 (not shown). 378 is a substrate. This structure is a structure in which a light emitting layer is sequentially formed in a plane parallel to the substrate 378 in a peripheral direction thereof.

In this device, three types of light emitting regions 370, 371, and 372 having light emitting layers made of three different materials.
Are arranged so as to surround the inner light emitting region in this order from the center of the element. In the manufacturing configuration of this element, first, the light emitting region 370 is formed, and then the light emitting region 37 is formed.
A light emitting area 371 around 0 and finally a light emitting area 3
72 were formed. By adopting such a shape, in any of the light-emitting regions in the manufacturing process, all of the cross section around the light-emitting region (that is, a portion serving as an interface between different light-emitting regions) passes through exactly the same process.

On the other hand, as a comparative example, in the case of FIG. 3B, the cross sections on both sides of the light emitting region 360 pass through two different processes for forming the light emitting regions 359 and 361, respectively. In this way, by adopting the configuration as shown in FIG. 4, it becomes possible to maintain the same quality in all portions of the peripheral cross section (interface) of each light emitting region 370, 371, 372. This means that three different light emitting areas 37
This shows that, regardless of the position of each of the interfaces 0, 371, and 372, the degree of introduction of crystal distortion due to interface leakage current and contact of different regions is the same. Therefore, it is possible to make each of the light emitting regions 370, 371, and 372 shine evenly.

It was also found that the light emitting device of FIG. 4 has a higher light emitting efficiency with respect to the applied power than the light emitting device of FIG. 3B. This is because when etching is performed to form light emitting layers having different emission wavelengths, only one kind of light emitting layer can be etched by one etching, so that etching conditions according to each light emitting layer can be adapted, This is considered to be because etching damage to the layer could be minimized.

In the above embodiment, an example using a sapphire substrate in a nitride semiconductor light emitting device has been described.
Adaptation is also possible in a substrate having conductivity such as -GaN. In this case, the electrodes can be formed on the growth surface and the back surface of the substrate, and there is an advantage that the etching process can be omitted when the device is manufactured. Furthermore, when a light emitting element is formed in series with an electrode, the order of forming a light emitting layer is such that when a substrate is made of a material that does not absorb light from the light emitting layer, light from the light emitting layer is applied to the substrate. Since it can be taken out from the side or from the growth surface, there is no problem if the light-emitting layers are stacked in ascending order of the emission wavelength from the substrate side, or conversely, the light-emitting layers are stacked in ascending order of the emission wavelength from the substrate side. Since it is necessary to adopt a structure in which light is extracted from the surface of the growth layer as long as it is made of a material that absorbs light from the substrate, light-emitting layers having long emission wavelengths are sequentially stacked from the substrate side in order to prevent absorption between the light-emitting layers. Is more advantageous. Although the above description has been given with reference to the example of a nitride semiconductor, for example, GaAs, InP
A light emitting element having a plurality of light emitting layers can be manufactured by this method in any of the semiconductors such as a GaSb-based or GaSb-based semiconductor or a semiconductor in which the third and fourth elements are added thereto. A light-emitting element having a plurality of bands can be easily obtained.

[0041]

As is apparent from the above description, according to the present invention, a light emitting device having a plurality of light emitting layers having different light emission wavelengths is manufactured. By using this method, for example, in the case of a nitride semiconductor, a light emitting element that emits white light or a light emitting element that emits light in an entire wavelength band in the entire range of visible light is manufactured. In addition, in a GaAs-based, InP-based, GaSb-based or a semiconductor in which the third and fourth elements are added thereto,
A light-emitting element that covers an arbitrary wavelength band required by infrared light can be manufactured.

The light emitting device can be used as a lamp or an illumination which requires a wide wavelength band, and can be effectively used as a light source for reading by a scanner. Since nitride semiconductors can be applied to light emitting devices of all wavelengths from the ultraviolet region to red, the present invention provides a light emitting device having a wide spectrum in a high energy band including blue, a white light emitting device, and the like. An element can be realized.

[Brief description of the drawings]

FIG. 1 is an example of a light-emitting element manufactured according to this embodiment.

FIG. 2 is a cross-sectional view of a white LED manufactured according to an example of the present embodiment.

3A and 3B are cross-sectional views of a light-emitting element manufactured according to an example of the present embodiment. FIG. 3A is an element that emits light of two different wavelengths, and FIG. 3B is an element that emits light of three different wavelengths. It is.

FIG. 4 is a cross-sectional view of a light-emitting element manufactured according to an example of the present embodiment, which is an element having another configuration that emits light of three different wavelengths.

FIG. 5 is an emission spectrum from a light-emitting element manufactured according to an example of the present embodiment.

FIG. 6 is an emission spectrum from a light-emitting element manufactured according to an example of the present embodiment.

[Explanation of symbols]

 101 substrate 102 n-type current injection layer 103, 105, 106 light-emitting layer 104 barrier layer 107 p-type current injection layer 108 p-type ohmic electrode 109 n-type ohmic electrode 201 substrate 202 n-type current injection layer 203, 204, 205 light-emitting layer 206 Barrier layer 207 p-type current injection layer 208 p-type ohmic electrode 209 n-type ohmic electrode 301 substrate 302, 306 n-type current injection layer 303, 307 light-emitting layer 304, 308 p-type current injection layer 305 309 contact layer 310 n-type ohmic electrode 311 p-type ohmic electrode 351 substrate 352, 353, 354 n-type current injection layer 356, 357, 358 light-emitting layer 359, 360, 361 p-type current injection layer 362 p-type ohmic electrode 363 n-type ohmic electrode 370, 371, 372 Region 3 3 light-emitting layer 374,379 n-type current injection layer 375 n-type ohmic electrode 376 p-type ohmic electrode 377 p-type current injection layer 378 substrate

Claims (7)

[Claims] 1. A semiconductor light-emitting element formed between a pair of electrodes, comprising two or more light-emitting layers having different wavelengths near both a p-type layer and an n-type layer. 2. The semiconductor light emitting device according to claim 1, wherein a plurality of light emitting layers having different emission wavelengths are provided in parallel between a pair of electrodes. 3. The semiconductor light emitting device according to claim 1, wherein a plurality of light emitting layers having different emission wavelengths are arranged in series between a pair of electrodes. 4. The semiconductor light emitting device according to claim 1, wherein said semiconductor light emitting device is a nitride semiconductor light emitting device. 5. The plurality of light emitting layers are nitride semiconductor light emitting layers containing In, wherein the respective light emitting layers have different In composition ratios, and the light emitting layer located closest to the substrate has the largest In composition ratio, 4. The semiconductor light emitting device according to claim 3, wherein the In composition ratio of the light emitting layer gradually decreases as the distance from the substrate increases. 6. The light-emitting layer is a nitride semiconductor light-emitting layer containing In. The light-emitting wavelength of the light-emitting layer located closest to the substrate has the lowest visibility, and the light-emitting wavelength of the light-emitting layer increases with distance from the substrate. 4. The semiconductor light emitting device according to claim 3, wherein the sensitivities increase in order. 7. The plurality of light-emitting layers are nitride semiconductor light-emitting layers containing In, and each light-emitting layer has a different In composition ratio and is formed in order from inside to outside in a plane parallel to the substrate, 3. The semiconductor light emitting device according to claim 2, wherein the outer light emitting layer is formed so as to surround the inner light emitting layer.