JP5737096B2 - Group III nitride semiconductor light emitting device - Google Patents

Description

  The present invention relates to a group III nitride semiconductor light-emitting device having a wide emission spectrum and high emission efficiency.

  As of 2011, white light emitting packages combining blue LEDs and yellow phosphors are used as LED bulbs for general lighting, etc., and have begun to spread rapidly due to their higher luminous efficiency and longer life compared to incandescent bulbs. Yes.

  In this white light emitting package, in order to stabilize the excitation efficiency of the phosphor, it is desired that the emission spectrum of the blue LED is wide.

  As group III nitride semiconductor light emitting devices having a wide emission spectrum, for example, there are Patent Documents 1 and 2. Patent Document 1 discloses that a plurality of inclined surfaces having different inclination angles are provided on the upper surface of a group III nitride semiconductor layer, and a light emitting layer is formed along the inclined surfaces. When the angle of the inclined surface is different, the emission wavelength of the region of the light emitting layer located thereon is different. As a result, the group III nitride semiconductor light-emitting device emits light at a plurality of emission wavelengths, and the emission spectrum is broadened.

  Patent Document 2 discloses a group III nitride semiconductor light-emitting device having a light-emitting layer with an MQW structure so that the band gap of each well layer of the light-emitting layer becomes smaller toward the n-type layer side. It has been shown. With the light emitting layer having such a structure, the carrier distribution spreads to each well layer, and the light emission wavelength in each well layer is different, so that the emission spectrum can be widened.

JP 2010-182832 A JP 2004-128443 A

  However, in Patent Document 1, it is necessary to provide inclined surfaces with different inclination angles on the upper surface of the group III nitride semiconductor layer. However, it is technically difficult to grow and process crystals so as to have such a structure. Is expensive, expensive and not a practical method.

  Further, in the method of Patent Document 2, the carrier distribution is widened, so that the holes overflow to the n-type layer side, the carrier injection efficiency into the light emitting layer is lowered, and the light emitting efficiency is lowered.

  Accordingly, an object of the present invention is to realize a group III nitride semiconductor light-emitting device having a broad emission spectrum and high emission efficiency.

According to a first aspect of the present invention, there is provided an n-contact layer, a light-emitting layer having an MQW structure, which is positioned in contact with the n-contact layer and in which a well layer made of InGaN and a barrier layer made of GaN or AlGaN are alternately and repeatedly stacked. In the group III nitride semiconductor light emitting device having the above, the In composition ratio of each well layer is from each of the first well layer closest to the n contact layer to the well layer closest to the n contact layer 3 to 10th. For the well layer, the In composition ratio is a predetermined value, and for each of the subsequent well layers, the In composition ratio is smaller than the predetermined value, and the well layer farther from the n contact layer side has a smaller In composition ratio. And the difference between the In composition ratio of the well layer having the highest In composition ratio and the In composition ratio of the well layer having the lowest In composition ratio is 5 to 20%. It is an element.
In the present specification, the following other inventions are also described. Group III nitride having an n contact layer and a light emitting layer having an MQW structure in which a well layer made of InGaN and a barrier layer made of GaN or AlGaN are alternately and repeatedly stacked a plurality of times, located above the n contact layer In a semiconductor light emitting device, a hole blocking layer made of n-AlGaN having a thickness of 5 to 100 mm is provided between an n contact layer and a light emitting layer, and the In composition ratio of each well layer is a well far from the n contact layer side. The group III nitride semiconductor light-emitting device is characterized in that the layer has a smaller In composition ratio.

In the present invention and other inventions described in the specification, the structure of the light emitting layer may be any conventionally known MQW structure in which a well layer made of InGaN and a barrier layer made of GaN or AlGaN are repeatedly stacked. Structure may be sufficient. For example, a cap layer made of GaN or AlGaN grown at the same temperature as the well layer may be provided between the well layer and the barrier layer. By providing the cap layer, it is possible to suppress the evaporation of In from the well layer at the temperature rise when forming the barrier layer.

The number of repetitions of the well layer and the barrier layer of the light emitting layer is desirably 4 to 20 times in the present invention and other inventions described in the specification . If the number of repetitions is within this range, the light emission efficiency can be more effectively improved.

In another invention described in the specification, the Al composition ratio of the hole block layer is desirably 10 to 30%. It is possible to suppress the occurrence of hole overflow more effectively and to improve the efficiency of carrier injection into the light emitting layer without hindering electron tunneling. A more desirable Al composition ratio of the hole block layer is 20 to 30%. The hole blocking layer is preferably doped with Si so that the Si concentration is 5 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ . When Si is doped in this range, the resistance of the element can be reduced, and the drive voltage can be lowered. The hole block layer is more preferably 5 to 50 mm thick. When the thickness is within this range, the occurrence of hole overflow can be suppressed more effectively, and the efficiency of carrier injection into the light emitting layer can be improved without impeding electron tunneling.

In the onset bright, well layer with constant In composition ratio is nearest the first well layer to the n-contact layer, it is more desirable to be up to the well layer closest to the 3-8-th to the n-contact layer. It is possible to suppress the occurrence of hole overflow more effectively and to improve the efficiency of carrier injection into the light emitting layer without hindering electron tunneling. More preferably, it is up to the third to fifth nearest well layer to the n contact layer.

In the present invention and other inventions described in the specification, most n contact layer In composition ratio near the well layer, namely the In composition ratio of the most In composition ratio a high well layer (predetermined value in the present onset bright) is 15 30% is desirable. If it is lower than 15%, the emission spectrum cannot be sufficiently broadened. If it is higher than 30%, the crystallinity of the well layer is deteriorated. More desirably, it is 20 to 30%. The In composition ratio of the well layer farthest from the n contact layer, that is, the In composition ratio of the well layer having the lowest In composition ratio is preferably 5 to 20%. If it is lower than 5%, it is difficult to confine carriers in the well layer, and if it is higher than 20%, the emission spectrum cannot be sufficiently expanded. More desirably, it is 10 to 20%. The difference between the In composition ratio of the well layer having the highest In composition ratio and the In composition ratio of the well layer having the lowest In composition ratio is preferably 5 to 20%. If it is this range, while being able to make a light emission spectrum sufficiently wide, the fall of luminous efficiency can be suppressed. Furthermore, (in this onset bright excluding section is In composition ratio is constant) difference in the In composition ratio of the adjacent well layers is preferably 1 to 5%. This is because the emission spectrum becomes more continuous and smooth.

In another invention described in the specification, the hole block layer may have an Al composition ratio of 10 to 30% .

In another invention described in the specification, the hole blocking layer may have a thickness of 5 to 50 mm .

In another invention described in the specification, the number of repetitions of the well layer and the barrier layer of the light emitting layer can be 4 to 20 times .

A second invention is a group III nitride semiconductor light-emitting device according to the first invention, characterized in that the In composition ratio is constant up to the third to the eighth closest well layer to the n-contact layer. is there.

A third invention is a group III nitride semiconductor light emitting device according to the first invention or the second invention, wherein the number of repetitions of the well layer and the barrier layer of the light emitting layer is 4 to 20 times. . A fourth invention is a group III nitride semiconductor light-emitting device according to any one of the first to third inventions, wherein the certain predetermined value is 15 to 30%.
A fifth invention is a group III nitride semiconductor light emitting device according to the first to fourth inventions, wherein the In composition ratio of the well layer farthest from the n contact layer is 5 to 20%. is there.

As in the present invention and other inventions described in the specification, the distribution of the In composition ratio of each well layer is a distribution in which the In composition ratio decreases with increasing distance from the n contact layer side, thereby broadening the carrier distribution. A broad emission spectrum can be obtained. However, as a result of the carrier distribution being widened, hole overflow occurs. Therefore, in the first invention, by providing a hole blocking layer made of n-AlGaN having a thickness of 10 to 100 mm between the n contact layer and the light emitting layer, In the fifth aspect of the invention, overflow is suppressed by keeping the In composition ratio of each of the 3 to 10 well layers on the n contact layer side constant. As a result, the efficiency of carrier injection into the light emitting layer is maintained, and the light emission efficiency can be improved.

FIG. 3 is a diagram showing a configuration of a group III nitride semiconductor light-emitting device of Example 1. The figure which showed the structure of the light emitting layer. The band diagram of the hole block layer 12 and the light emitting layer 13. The figure which showed the emission spectrum of the group III nitride semiconductor light-emitting device of Example 1. FIG. 3 is a diagram showing a configuration of a group III nitride semiconductor light-emitting device of Example 2. The figure which showed the structure of the light emitting layer. The band figure of the light emitting layer 23. FIG.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to the examples.

  FIG. 1 is a diagram showing the configuration of the group III nitride semiconductor light emitting device of Example 1. The group III nitride semiconductor light emitting device of Example 1 has a sapphire substrate 10, and an n contact layer 11, a hole blocking layer 12, and a light emitting layer 13 via a buffer layer (not shown) made of AlN on the sapphire substrate 10. , A p-cladding layer 14 and a p-contact layer 15 are sequentially stacked. A groove having a depth reaching the n contact layer 11 from the surface is formed in a partial region of the surface of the p contact layer 15, and an n electrode 16 is provided on the n contact layer 11 exposed on the bottom surface of the groove. It has been. A transparent electrode 17 made of ITO is provided on almost the entire surface except the groove forming portion on the p contact layer 15, and a p electrode 18 is provided on the transparent electrode 17.

An uneven pattern such as a dot shape or a stripe shape may be provided on the surface of the sapphire substrate 10 on the n contact layer 11 side so as to improve the light extraction efficiency. Besides the sapphire substrate, SiC, Si, ZnO, spinel, GaN, Ga ₂ O ₃ or the like can be used as the growth substrate.

The n contact layer 11 is made of n-GaN having a thickness of 4 μm and a Si concentration of 2 × 10 ¹⁸ / cm ³ . In order to further reduce the contact resistance with the n-electrode 16, the n-contact layer 11 may be composed of a plurality of layers having different Si concentrations.

The hole blocking layer 12 is made of n-AlGaN having a thickness of 100 mm, a Si concentration of 2 × 10 ¹⁸ / cm ³ , and an Al composition ratio of 20%.

The thickness and Al composition ratio of the hole blocking layer 12 may be any thickness and Al composition ratio that can tunnel electrons and block holes. 100% and Al composition ratio may be 10 to 30%. More desirably, the thickness is 5 to 50 mm and the Al composition ratio is 20 to 30%. The Si concentration of the hole blocking layer 12 may be in the range of 5 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ .

An ESD layer may be provided between the hole block layer 12 and the n contact layer 11 in order to increase electrostatic withstand voltage. The ESD layer has the following configuration, for example. In order from the n-contact layer 11 side, a three-layer structure of a first ESD layer, a second ESD layer, and a third ESD layer is formed, and the first ESD layer has pits of 1 × 10 ⁸ / cm ² or less formed on the surface on the light emitting layer 13 side. , Having a thickness of 200 to 1000 nm and a Si concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁷ / cm ³ , and the second ESD layer has a surface of 2 × 10 ⁸ / cm ² or more on the light emitting layer 13 side. A pit is formed, the GaN is composed of GaN having a thickness of 50 to 200 nm and a carrier concentration of 5 × 10 ¹⁷ / cm ³ or less. The ^third ESD layer is a product of Si concentration (/ cm ³ ) and film thickness (nm). It is composed of GaN having a defined characteristic value of 0.9 × 10 ^{20 to} 3.6 × 10 ²⁰ (nm / cm ³ ). By configuring the ESD layer in this manner, it is possible to improve the light emission efficiency and reliability while improving the electrostatic withstand voltage characteristics, and to reduce current leakage.

  As shown in FIG. 2, the light emitting layer 13 has an MQW structure in which four pairs are repeatedly stacked with a well layer 130 made of InGaN and a barrier layer 131 made of GaN as one pair. The well layer 130 is a well layer 130-1, 130-2, 130-3, 130-4 in order from the side closer to the n contact layer 11. The In composition ratio of the well layer 130-1 is x1 (unit is%, the same applies hereinafter), the In composition ratio of the well layer 130-2 is x2, the In composition ratio of the well layer 130-3 is x3, and the well layer 130-4 If the In composition ratio of x is x4, the well layers 130-1 to 130-4 are configured to satisfy x1> x2> x3> x4. That is, the well layer 130 is configured such that the closer to the n-contact layer 11 the higher the In composition ratio and the lower the distance, the lower the In composition ratio.

  x1 is preferably 15 to 30%. If it is lower than 15%, the emission spectrum cannot be sufficiently broadened. If it is higher than 30%, the crystallinity of the well layer 130-1 is deteriorated. More desirably, it is 20 to 30%. x4 is preferably 5 to 20%. If it is lower than 5%, it is difficult to confine carriers in the well layer 130-4, and if it is higher than 20%, the emission spectrum cannot be sufficiently expanded. More desirably, it is 10 to 20%. The difference between x1 and x4 is preferably 5 to 20%. If it is this range, while being able to make a light emission spectrum sufficiently wide, the fall of luminous efficiency can be suppressed. The difference between adjacent well layers 130, that is, the difference between x1 and x2, the difference between x2 and x3, and the difference between x3 and x4 is preferably 1 to 5%. This is because the emission spectrum becomes more continuous and smooth.

  In the light emitting layer 13 of Example 1, GaN is used as the barrier layer 131, but AlGaN may be used. When AlGaN is used, the Al composition ratio is desirably 5 to 10%. Further, a cap layer formed at the same temperature as the well layer 130 may be provided between the well layer 130 and the barrier layer 131. It is possible to suppress the evaporation of In in the well layer 130 during the temperature rise when the barrier layer 131 is formed. In Example 1, the number of repetitions of the well layer 130 and the barrier layer 131 is four. However, if the number of repetitions is 4 to 20, the light emission efficiency can be sufficiently increased.

p-cladding layer 14 has a thickness of 2 nm, a p-AlGaN layer of Mg concentration 5 × 10 ¹⁹ / cm ^3, a thickness of 2 nm, and a p-InGaN layer of Mg concentration 5 × 10 ¹⁹ / cm ³ as a unit, This is a superlattice structure in which 7 units are repeatedly laminated. However, the first layer, that is, the layer in contact with the light emitting layer 13 is a p-InGaN layer, and the last layer, that is, the layer in contact with the p contact layer 15 is a p-AlGaN layer. The p-clad layer 14 may be a single layer made of p-AlGaN.

The p contact layer 15 is made of p-GaN having a thickness of 10 nm and an Mg concentration of 1.0 × 10 ²¹ / cm ³ . In order to achieve both improvement in crystallinity and reduction in contact resistance with the transparent electrode 17, the p contact layer 15 may be composed of a plurality of layers having different Mg concentrations. For example, in order from the p-cladding layer 14 side, a first p contact layer made of GaN having an Mg concentration of 1 to 3 × 10 ¹⁹ / cm ³ and a thickness of 320 mm, and a Mg concentration of 4 to 6 × 10 ¹⁹ / cm ³ and a thickness of 320 mm A three-layer structure of a second p-contact layer made of GaN and a third p-contact layer made of GaN having an Mg concentration of 1 to 2 × 10 ²⁰ / cm ³ and a thickness of 80 mm may be adopted. Further, the third p contact layer in contact with the transparent electrode 17 may be InGaN instead of GaN. Since the work function is close to that of the transparent electrode 17, the contact resistance can be further reduced.

  The transparent electrode 17 is provided on almost the entire surface of the p contact layer 15. In addition to ITO, the transparent electrode 17 can be made of a transparent oxide conductor material such as ICO (cerium-doped indium oxide) or IZO (zinc-doped indium oxide), or a metal thin film such as Au.

  In order to improve current diffusibility, the n electrode 16 and the p electrode 18 are connected to a pad portion to which a wire is bonded and a wiring shape (for example, a lattice shape, a comb tooth shape, a radial shape) in a plane. It is good also as a structure which has a wiring-shaped part to do.

  FIG. 3 shows a band diagram for the group III nitride semiconductor layer (layer stacked in order from the n contact layer 11 to the p contact layer 15) of the group III nitride semiconductor light-emitting device of Example 1. As shown in FIG. 3, since the In composition ratio of the well layer 130 of the light emitting layer 13 decreases as the distance from the n contact layer 11 increases, the band gap gradually increases as the distance from the n contact layer 11 increases. When the band gap of the well layer 130 has such a distribution, light emission occurs due to the difference in mobility of electrons and holes in the group III nitride semiconductor (the mobility of holes is smaller than the mobility of electrons). Carrier distribution spreads in each of the well layers 130-1 to 130-4 in the layer 13. Since the emission wavelengths of the well layers 130-1 to 130-4 are different, a wide emission spectrum can be obtained.

  However, as a result of the carrier distribution spreading, the holes overflow to the n contact layer 11 side. Therefore, in the group III nitride semiconductor light-emitting device of Example 1, hole overflow is suppressed by providing the hole blocking layer 12 made of n-AlGaN having a thickness of 100 mm and an Al composition ratio of 20%. The effect of blocking holes increases as the Al composition ratio increases, that is, as the band gap increases, and increases as the hole blocking layer 12 increases. On the other hand, if the Al composition ratio is too high or the hole blocking layer 12 is too thick, the efficiency with which electrons are injected into the light emitting layer 13 is lowered. Therefore, the thickness of the hole block layer 12 is 100 mm, and the Al composition ratio is 20%. By providing the hole blocking layer 12 in this manner, the efficiency of carrier injection into the light emitting layer 13 is maintained, and as a result, the light emitting efficiency can be improved.

  4 is a graph showing an emission spectrum of the group III nitride semiconductor light-emitting device of Example 1. FIG. In this case, the drive currents are 20 mA, 100 mA, and 200 mA, respectively. In either case, it can be seen that the emission spectrum is wide with a full width at half maximum of approximately 40 nm. Further, it can be seen that the shape of the emission spectrum is continuous and smooth and is not a shape having a plurality of peaks. It can also be seen that the spectrum shape changes with the drive current. This is because, when a white light emitting package in which the group III nitride semiconductor light emitting device of Example 1 is sealed with a resin mixed with a yellow phosphor is prepared, the chromaticity of the white light emitting package can be adjusted by the drive current. Is shown.

  As described above, in the group III nitride semiconductor light emitting device of Example 1, the In composition ratio of the well layers 130-1 to 130-4 of the light emitting layer 13 is set to be farther from the n contact layer 11 and the In composition ratio is higher. Further, a hole blocking layer 12 having a thickness of 100 mm and an Al composition ratio of 20% is provided between the n contact layer 11 and the light emitting layer 13. As a result, a Group III nitride semiconductor light-emitting device having a wide emission spectrum and high emission efficiency is realized.

  FIG. 5 is a diagram showing the configuration of the group III nitride semiconductor light emitting device of Example 2. As shown in FIG. 5, the Group III nitride semiconductor light-emitting device of Example 2 is the same as the Group III nitride semiconductor light-emitting device of Example 1, except that the hole blocking layer 12 is omitted and the light-emitting layer 13 is replaced. The light emitting layer 23 is provided.

  As shown in FIG. 6, the light emitting layer 23 has an MQW structure in which a well layer 230 made of InGaN and a barrier layer 231 made of GaN are paired and 10 pairs are repeatedly stacked. The well layer 230 is referred to as well layers 230-1, 230-2, 230-3,..., 230-10 in order from the side closer to the n contact layer 11. If the In composition ratio of the well layer 230-i (1 ≦ i ≦ 10) is yi (unit:%), y1 = y2 = y3. That is, the first to third well layers 230-1 to 230-3 from the n contact layer 11 side have the same In composition ratio (composition ratio at which the emission wavelength is 450 nm). Further, y3> y4> y5>...> Y9> y10. y10 is the composition ratio at which the emission wavelength is 420 nm. In other words, the fourth and subsequent well layers 230-4 to 230-10 from the n contact layer 11 side all have an In composition ratio lower than that of the well layer 230-3 and closer to the n contact layer 11, the In composition ratio. The well layers 230-4 to 230-10 are configured such that the In composition ratio decreases as the distance increases.

  In the light emitting layer 23 of Example 2, GaN is used as the barrier layer 231, but AlGaN may be used. When AlGaN is used, the Al composition ratio is desirably 5 to 10%. Further, a cap layer formed at the same temperature as the well layer 230 may be provided between the well layer 230 and the barrier layer 231. It is possible to suppress the evaporation of In in the well layer 230 during the temperature rise when the barrier layer 231 is formed. In Example 2, the number of repetitions of the well layer 230 and the barrier layer 231 is 10 times. However, if the number of repetitions is 4 to 20, the light emission efficiency can be sufficiently improved.

  FIG. 7 shows a band diagram for the group III nitride semiconductor layer (layer stacked in order from the n contact layer 11 to the p contact layer 15) of the group III nitride semiconductor light emitting device of Example 2. As shown in FIG. 7, the well layer 230 has a constant band gap because the In composition ratio is constant for the first to third well layers 230-1 to 230-3 from the n-contact layer 11 side. Further, in the fourth and subsequent well layers 230-4 to 230-10 from the n contact layer 11 side, the In composition ratio decreases as the distance from the n contact layer 11 increases. It gets bigger and bigger as you leave. When the band gap of the well layers 230-4 to 230-10 has such a distribution, the difference between the mobility of electrons and holes in the group III nitride semiconductor (the mobility of holes is smaller than the mobility of electrons). As a result, the carrier distribution spreads in each of the well layers 230-4 to 230-10 in the light emitting layer 23. Since each of the well layers 230-4 to 230-10 has a different emission wavelength, a wide emission spectrum can be obtained.

  However, as a result of the carrier distribution spreading, the holes overflow to the n contact layer 11 side. Therefore, in the group III nitride semiconductor light-emitting device of Example 2, well layers 230-1 to 230-3 having an In composition ratio higher than the well layer 230-4 and constant are provided on the n contact layer 11 side. . In the well layers 230-1 to 230-3, the overflow of holes is suppressed by joining holes to overflow with electrons. As a result, the efficiency of carrier injection into the light emitting layer 23 is maintained, and as a result, the light emission efficiency can be improved.

  The effect of suppressing the overflow of holes becomes higher as the number of the well layers 230 having a constant In composition ratio on the n contact layer 11 side increases. On the other hand, if the number of the well layers 230 having a constant In composition ratio is too large, the number of electrons reaching the well layer on the side away from the n contact layer 11 decreases, the carrier distribution in the light emitting layer 23 is biased, and the width of the light emission spectrum. Becomes narrower. Therefore, it is desirable that the well layer 230 having a constant In composition ratio is from the first to the third to the tenth from the n-contact layer 11 side. Within this range, it is possible to obtain a broad emission spectrum while efficiently suppressing the hole overflow and improving the emission efficiency. More desirably, it is the third to eighth, and more desirably third to fifth.

  Although the group III nitride semiconductor light emitting device of Examples 1 and 2 was a face-up type device, the present invention is not limited to this, and the group III nitride semiconductor light emitting device of any conventionally known structure is used. It can be applied to an element. For example, the present invention can also be applied to a flip chip type element, an element using a conductive substrate, or an element having a structure that conducts in the vertical direction by removing the substrate by a technique such as laser lift-off. . And like Example 1, 2, luminous efficiency can be improved, obtaining a wide light emission spectrum. In the case of a flip-chip type element or a laser lift-off element, light is extracted from the well layer side with a high In composition ratio, but light absorption in the well layer with a high In composition ratio is slight, which is a problem. The light can be taken out.

  The group III nitride semiconductor light-emitting device of the present invention is particularly effective for use in lighting devices.

10: sapphire substrate 11: n contact layer 12: hole blocking layer 13, 23: light emitting layer 14: p cladding layer 15: p contact layer 16: n electrode 17: transparent electrode 18: p electrode 130, 230: well layer 131, 231: barrier layer

Claims (5)

a group III having an n-contact layer and a light-emitting layer having an MQW structure, which is located in contact with the n-contact layer and in which a well layer made of InGaN and a barrier layer made of GaN or AlGaN are alternately and repeatedly stacked a plurality of times In the nitride semiconductor light emitting device,
The In composition ratio of each well layer is the In composition ratio for each well layer from the first well layer closest to the n contact layer to the well layer closest to the third to tenth to the n contact layer. There is a constant predetermined value, for each of the well layers of the later, smaller than the in composition ratio is the predetermined value, and said n from the contact layer side farther well layer in composition ratio rather small, most in The difference between the In composition ratio of the well layer having a high composition ratio and the In composition ratio of the well layer having the lowest In composition ratio is 5 to 20%.
A group III nitride semiconductor light emitting device characterized by the above. 2. The group III nitride semiconductor light-emitting device according to claim 1 , wherein the In composition ratio is constant from the third to the eighth closest well layer to the n-contact layer. 3. The group III nitride semiconductor light emitting device according to claim 1 , wherein the number of repetitions of the well layer and the barrier layer of the light emitting layer is 4 to 20 times. The group III nitride semiconductor light-emitting device according to any one of claims 1 to 3, wherein the predetermined predetermined value is 15 to 30%. 5. The group III nitride semiconductor light-emitting device according to claim 1, wherein an In composition ratio of a well layer farthest from the n-contact layer is 5 to 20%.

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