JP2021034521A - Light-emitting device and manufacturing method thereof - Google Patents

Abstract

To realize an ultraviolet light-emitting device consisting of a group III nitride semiconductor with high luminous efficiency and low resistance.SOLUTION: A light-emitting element includes an n-contact layer 12 and a light-emitting layer 13 provided on the n-contact layer 12. The surfaces of the n-contact layer 12 and the light emitting layer 13 have a concave-convex shape in which bowl-shaped convex portions 20 are two-dimensionally distributed, and spiral dislocations 21 are present near the center of the convex portions 20, and there is an energy region 22 having higher Al composition in the vicinity of the spiral dislocations 21 than the other regions 23 in the n-contact layer 12. Since the high energy region 22 forms a potential barrier for carriers, the luminous efficiency is improved.SELECTED DRAWING: Figure 2

Description

The present invention relates to a light emitting device made of a group III nitride semiconductor, and more particularly to a light emitting device that emits ultraviolet light. It also relates to a method for manufacturing the light emitting element.

Patent Document 1 is a technique for improving the light output of an ultraviolet light emitting device made of a group III nitride semiconductor. Patent Document 1 describes that the surface of a substrate made of sapphire is formed into a multi-stage terrace shape, and the light emitting layer is also formed into a multi-stage terrace shape by step-flow growing a group III nitride semiconductor on the substrate. By forming the light emitting layer in such a shape, Ga is segregated in the stepped portion to improve the light output.

International Publication No. 2017/013729

However, even if the light emitting layer has a multi-stage terrace shape as in Patent Document 1, the segregation rate of Ga is small and the improvement in light output is not sufficient. Further, Patent Document 1 has a problem that the light emitting layer does not emit light uniformly in the plane and a problem that the resistance reduction is not sufficient.

Therefore, an object of the present invention is to realize an ultraviolet light emitting device made of a group III nitride semiconductor having high luminous efficiency.

The present invention relates to an ultraviolet light emitting device composed of a group III nitride semiconductor having an n layer, a light emitting layer located on the n layer, and a p layer located on the light emitting layer, the surface of the n layer and light emission. The layer surface has a concave-convex shape in which bowl-shaped convex parts are distributed in two dimensions, and spiral dislocations or compound dislocations are present near the center of the convex parts, and the region near the spiral dislocations or compound dislocations is , A light emitting device characterized by having a higher band gap energy than other regions.

The height of the convex portion is preferably 2 to 10 nm, the diameter of the convex portion is preferably 100 to 2000 nm, and the average roughness of the n-layer surface and the light emitting layer surface is preferably 2 to 10 nm. Within this range, the luminous efficiency can be further improved.

The density of the protrusions is preferably ^{1 × 10 6} to 1 × 10 ⁸ / cm ^2. Within this range, the luminous efficiency can be further improved.

The Si concentration of the n-layer is preferably ^{1 × 10 19 to} 5 × 10 ¹⁹ / cm ^3. The resistance of the light emitting element can be reduced.

Further, the present invention relates to a method for manufacturing an ultraviolet light emitting device made of a group III nitride semiconductor having an n layer, a light emitting layer located on the n layer, and a p layer located on the light emitting layer. The layer is formed under the conditions that the growth temperature is 850 to 1100 ° C., the V / III ratio is 500 to 3200, the growth temperature is T (° C.), and the V / III ratio is R, and 20T + R ≦ 24000 is satisfied. The surface of the n-layer and the surface of the light-emitting layer have a concave-convex shape in which bowl-shaped convex parts are two-dimensionally distributed. It is a method for manufacturing a light emitting element, characterized in that the band gap energy is higher than that in other regions.

For the formation of the n-layer, it is preferable that the growth temperature is 1000 to 1050 ° C. and the V / III ratio is 1050 to 2200. Luminous efficiency can be further improved.

According to the present invention, since the vicinity of the center of the convex portion has a high Al composition, a potential barrier is formed with respect to the carrier, and the carrier is not trapped by a spiral dislocation or a composite dislocation at the center of the convex portion, or other dislocations in the vicinity thereof. , The luminous efficiency can be improved.

The figure which showed the structure of the light emitting element of Example 1. FIG. The figure which shows typically the surface shape of n contact layer 12 and light emitting layer 13. The figure which shows typically the energy band figure around the convex part 20. An AFM image of the surface of the light emitting layer 13. The figure which showed the light emission intensity distribution of a light emitting layer 13. The figure which showed the CL image of the light emitting layer 13. The graph which showed the current-light output characteristic of the light emitting element of Example 1. FIG. The graph which showed the relationship between the resistivity of n-AlGaN and the Si concentration. STEM image near the convex part 20.

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

FIG. 1 is a diagram showing a configuration of a light emitting element of the first embodiment. The light emitting element of Example 1 is a flip-chip type ultraviolet light emitting element, and includes a substrate 10, a buffer layer 11, an n-contact layer 12, a light-emitting layer 13, an electron block layer 14, and a p-contact layer 15. It has a transparent electrode 16, a p electrode 17, and an n electrode 18. The n-contact layer 12 corresponds to the n-layer of the present invention, and the electron block layer 14 and the p-contact layer 15 correspond to the p-layer of the present invention.

(Structure of each layer)
First, the configuration of each layer of the light emitting element of the first embodiment will be described.

The substrate 10 is a growth substrate made of sapphire. The thickness is, for example, 900 μm. In addition to sapphire, AlN, Si, SiC, ZnO and the like can be used.

The buffer layer 11 is located on the substrate 10. The buffer layer 11 has a structure in which three layers of a nuclear layer, a low temperature buffer layer, and a high temperature buffer layer are laminated in this order. The nuclear layer is composed of non-doped AlN grown at a low temperature and is a layer that becomes a core of crystal growth. The thickness of the nuclear layer is, for example, 10 nm. The low temperature buffer layer is a layer made of non-doped AlN grown at a temperature higher than that of the nuclear layer. The thickness of the low temperature buffer layer is, for example, 0.3 μm. The high temperature buffer layer is a layer made of non-doped AlN grown at a higher temperature than the low temperature buffer layer. The thickness of the high temperature buffer layer is, for example, 2.7 μm. By providing such a buffer layer 11, the density of through dislocations of AlN is reduced.

The n-contact layer 12 is located on the buffer layer 11. The n-contact layer 12 is made of n-AlGaN. The Si concentration is preferably 1 × 10 ^{19 to} 5 × 10 ¹⁹ / cm ³ . This is because, as will be described later, both the improvement of the luminous efficiency and the reduction of the resistance of the light emitting element of the first embodiment can be achieved. As an example of the configuration of the n-contact layer 12, the Al composition is 62%, the thickness is 1.3 μm, and the Si concentration is 2 × 10 ¹⁹ / cm ³ .

The light emitting layer 13 is located on the n contact layer 12. The light emitting layer 13 has an MQW structure having two well layers. That is, the structure is such that the first barrier layer, the first well layer, the second barrier layer, the second well layer, and the third barrier layer are laminated in this order. The first well layer and the second well layer are made of n-AlGaN. The Al composition is set according to a desired emission wavelength. The first barrier layer, the second barrier layer, and the third barrier layer are made of n-AlGaN having a higher Al composition than the first well layer and the second well layer. As an example of the composition of the first well layer and the second well layer, the Al composition is 40%, the thickness is 2.4 nm, and the Si concentration is 9 × 10 ¹⁸ / cm ³ . As an example of the composition of the first barrier layer and the second barrier layer, the Al composition is 55%, the thickness is 19 nm, and the Si concentration is 9 × 10 ¹⁸ / cm ³ . As an example of the composition of the third barrier layer, the Al composition is 55%, the thickness is 4 nm, and the Si concentration is 5 × 10 ¹⁸ / cm ³ .

The electron block layer 14 is located on the light emitting layer 13. The electron block layer 14 is made of p-AlGaN having a higher Al composition than the third barrier layer. The electron block layer 14 suppresses the diffusion of electrons toward the p-contact layer 15. As an example of the structure of the electron block layer 14, the Al composition is 80%, the thickness is 25 nm, and the Mg concentration is 5 × 10 ¹⁹ / cm ³ .

The p-contact layer 15 is located on the electron block layer 14. The p-contact layer 15 has a structure in which a first p-contact layer and a second p-contact layer are laminated in this order. The first p-contact layer and the second p-contact layer are made of p-GaN. As an example of the structure of the first p contact layer, the thickness is 700 nm and the Mg concentration is 2 × 10 ¹⁹ / cm ³ . Further, as an example of the configuration of the second p contact layer, the thickness is 60 nm and the Mg concentration is 1 × 10 ²⁰ / cm ³ .

A groove is provided in a part of the surface of the p-contact layer 15. The groove is deep enough to penetrate the p-contact layer 15 and the light-emitting layer 13 and reach the n-contact layer. This groove is for providing the n electrode 18.

The transparent electrode 16 is located on the p-contact layer 15. The material of the transparent electrode 16 is, for example, a transparent conductive oxide such as IZO, ITO, ICO, and ZnO. Transparency here means that the transmittance in the visible light wavelength region is high.

The p-electrode 17 is located on the transparent electrode 16. The p electrode 17 is Ni / Au or the like.

The n-electrode 18 is located on the n-contact layer 12 exposed on the bottom surface of the groove. The n electrode 18 is Ti / Al / Ni, V / Al / Ni, V / Al / Ru, or the like.

(About the surface shape of each layer)
Next, the surface shape of each layer of the light emitting element of Example 1 will be described.

The surface of the n-contact layer 12 has a concave-convex shape in which bowl-shaped convex portions 20 are two-dimensionally distributed (see FIG. 2). Further, the surface of the n-contact layer 12 has less unevenness than the surface of the buffer layer 11, and the average roughness of the surface of the n-contact layer 12 is smaller than the surface roughness of the buffer layer 11.

The convex portion 20 exists corresponding to the position of the spiral dislocation, and the spiral dislocation 21 exists near the center of the convex portion 20. This is because the convex portion 20 is a spiral growth of crystals around the spiral dislocation 21. Therefore, the density of the convex portion 20 is approximately the same as the density of the spiral dislocations. The spiral dislocation 21 may be a composite dislocation of a spiral dislocation and a blade dislocation. Hereinafter, the term "spiral dislocation 21" includes the case of compound dislocations. Further, many blade-shaped dislocations and composite dislocations (composite dislocations of spiral dislocations and blade-shaped dislocations) also exist in the convex portion 20.

The density of the convex portion 20 is preferably ^{1 × 10 6} to 1 × 10 ⁸ / cm ^2. Within this range, the luminous efficiency can be further improved. For example, in Example 1, the density of the convex portion 20 is 7.8 × 10 ⁷ / cm ² .

The preferred shape of the convex portion 20 is as follows. The height H of the convex portion 20 is 2 to 10 nm. The diameter R of the convex portion is 100 to 2000 nm. For example, in Example 1, the diameter R of the convex portion is in the range of 200 to 800 nm. The average roughness of the surface of the n-contact layer 12 is 2 to 10 nm. The average roughness of the surface of the n-contact layer 12 is preferably larger than the thickness of the first well layer and the second well layer in the light emitting layer 13.

The region near the center of the convex portion 20 (the region near the spiral dislocation 21) has an Al composition higher than that of the other region 23 of the n-contact layer 12, or has a bandgap energy higher than that of the other region 23 due to crystal strain. There is an increasing high energy region 22. The high energy region 22 is substantially circular in a plan view, and is circular with a diameter of 100 to 1000 nm centered on the spiral dislocation 21. The bandgap energy of the high energy region 22 is, for example, 4.4 to 5 eV, and the bandgap energy difference between the high energy region 22 and the other region 23 is, for example, 0.1 to 0.6 eV.

The surface of the light emitting layer 13 inherits the surface shape of the surface of the n-contact layer 12 as it is. That is, the bowl-shaped convex portion 20 has a concave-convex shape in which the convex portion 20 is two-dimensionally distributed, the spiral dislocation 21 exists near the center of the convex portion 20, and the high-energy region 22 exists in the region near the spiral dislocation 21. ing. The height H, diameter R, density, and average roughness of the surface of the light emitting layer 13 of the convex portion 20 are also the same as those of the surface of the n contact layer 12.

In the light emitting element of the first embodiment, the surface shape of the light emitting layer 13 is set as described above, so that the luminous efficiency is improved. The reason will be described with reference to the energy band diagram shown in FIG. FIG. 3 is a diagram schematically showing an energy band diagram in the plane of the light emitting layer 13, and shows the vicinity of the convex portion 20. A spiral dislocation 21 exists near the center of the bowl-shaped convex portion 20. The spiral dislocation 21 forms a trap level, and the carriers trapped in the trap level are non-emissive-bonded. Therefore, the spiral dislocation 21 is a factor that lowers the luminous efficiency.

In the light emitting device of the first embodiment, the high energy region 22 is formed around the spiral dislocation 21, and the bandgap energy is larger than that of the other regions 23 of the light emitting layer 13. Therefore, the high energy region 22 forms a potential barrier with respect to carriers. Due to the presence of this potential barrier, carriers trapped in the spiral dislocation 21 and other dislocations existing in the vicinity of the spiral dislocation 21 are reduced, and non-luminescent bonds are also reduced. In addition, the number of carriers that emit light and bond in the other region 23 of the light emitting layer 13 increases accordingly. As described above, the luminous efficiency is improved by reducing the carriers trapped in the spiral dislocation 21 and other dislocations in the vicinity thereof and increasing the number of carriers that are luminescently bonded.

As described above, in the light emitting element of the first embodiment, the surface shape of the light emitting layer 13 is a concave-convex shape in which bowl-shaped convex portions 20 are two-dimensionally distributed, and spiral dislocations 21 are present near the center of the convex portions 20. Since the high energy region 22 exists around the dislocation 21, the luminous efficiency is improved.

(About the manufacturing method of the light emitting element of Example 1)
Next, a method of manufacturing the light emitting element of the first embodiment will be described. The MOCVD method is used for crystal growth of group III nitride semiconductors, ammonia is used as the nitrogen source, trimethylgallium is used as the Ga source, and trimethylaluminum is used as the Al source. Further, silane is used as the n-type dopant gas, and bis (cyclopentadienyl) magnesium is used as the p-type dopant gas. Further, hydrogen and nitrogen are used as the carrier gas.

First, a substrate 10 made of sapphire is prepared. Then, the buffer layer 11 is formed on the substrate 10. To form the buffer layer 11, first, a nuclear layer made of AlN is formed by sputtering. The growth temperature is, for example, 880 ° C. Next, a low-temperature buffer layer and a high-temperature buffer layer made of AlN are sequentially formed on the nuclear layer by the MOCVD method. The growth conditions of the low temperature buffer layer are, for example, a growth temperature of 1090 ° C. and a growth pressure of 5 kPa. The growth conditions of the high temperature buffer layer are, for example, a growth temperature of 1270 ° C. and a growth pressure of 5 kPa.

Next, an n-contact layer 12 made of n-AlGaN is formed on the buffer layer 11 by the MOCVD method. The growth temperature is 850 to 1100 ° C., the V / III ratio is 500 to 3200, and the growth pressure is 2 to 20 kPa. Further, the growth temperature is T (° C.) and the V / III ratio is R, so that 20T + R ≦ 24000 is satisfied. By setting the growth temperature and the V / III ratio in such a range, n-AlGaN can be spirally grown around the spiral dislocation 21, and the spirally grown portion becomes a bowl-shaped convex portion 20. As a result, the surface shape of the n-contact layer 12 becomes a concave-convex shape in which the bowl-shaped convex portions 20 are two-dimensionally distributed. In addition, this spiral growth is step flow growth (growth from the step is dominant rather than from the terrace), and Ga is taken in by the step. Therefore, the segregation of Ga in the in-plane direction is smaller than that in the conventional case where the uneven shape is a multi-stage terrace shape. Further, by forming the convex portion 20 in this way, the high energy region 22 can be formed around the spiral dislocation 21 near the center of the convex portion 20. The Al composition in the high energy region 22 is high because Al is difficult to migrate and is easily trapped around dislocations. Conversely, there are more dislocations in the vicinity of the center of the convex portion 20 than in the other regions 23.

Further, at the above growth temperature, the Si concentration of the n-contact layer 12 is preferably ^{1 × 10 19 to} 5 × 10 ¹⁹ / cm ^3. Within this range, it is possible to improve the luminous efficiency by making the surface shape of the n-contact layer 12 the above-mentioned uneven shape, and to reduce the resistance of the n-contact layer 12.

More preferable growth conditions for the n-contact layer 12 for forming the uneven shape are as follows. The growth temperature is preferably 1000 to 1050 ° C. The V / III ratio is preferably 1050 to 2200.

Next, the light emitting layer 13 is formed on the n contact layer 12 by the MOCVD method. The light emitting layer 13 is formed by laminating the first barrier layer, the first well layer, the second barrier layer, the second well layer, and the third barrier layer in this order. The growth conditions of the light emitting layer 13 are, for example, a growth temperature of 975 ° C. and a growth pressure of 40 kPa. Here, since the light emitting layer 13 is sufficiently thin, the surface shape of the n contact layer 12 is inherited, and the surface shape of the light emitting layer 13 is substantially the same as the surface shape of the n contact layer 12. That is, the bowl-shaped convex portion 20 has a concave-convex shape in which the convex portion 20 is two-dimensionally distributed, and has a high energy region 22 around the spiral dislocation 21 near the center of the convex portion 20.

Next, the electron block layer 14 is formed on the light emitting layer 13 by the MOCVD method. The growth conditions of the electron block layer 14 are, for example, a growth temperature of 1025 ° C. and a growth pressure of 5 kPa. Since the electron block layer 14 is also thin, the surface shape of the light emitting layer 13 is inherited.

Next, the p-contact layer 15 is formed on the electron block layer 14 by the MOCVD method. The p-contact layer 15 is formed by laminating the first p-contact layer and the second p-contact layer in this order. Here, as the p-contact layer 15 grows, its surface becomes flatter than the surfaces of the n-contact layer 12 and the light emitting layer 13. The growth conditions of the first p contact layer are, for example, a growth temperature of 1050 ° C. and a growth pressure of 20 kPa. The growth conditions of the second p-contact layer are, for example, a growth temperature of 1050 ° C. and a growth pressure of 10 kPa.

Next, a predetermined region on the surface of the p-contact layer 15 is dry-etched to form a groove having a depth reaching the n-contact layer 12.

Next, the transparent electrode 16 is formed on the p-contact layer 12. Next, the p electrode 17 is formed on the transparent electrode 16, and the n electrode is formed on the n contact layer 12 exposed on the bottom surface of the groove. The transparent electrode 16, the p electrode 17, and the n electrode 18 are formed by sputtering, vapor deposition, or the like. As described above, the light emitting element of Example 1 is manufactured.

(Results of various experiments)
Next, various experimental results regarding the light emitting device of Example 1 will be described.

FIG. 4 is an AFM image obtained by photographing the surface of the light emitting layer 13. FIG. 4A shows a growth temperature of 1013 ° C. and a V / III ratio of 1587, FIG. 4B shows a growth temperature of 1013 ° C. and a V / III ratio of 3174, and FIG. 4C shows a growth temperature of 1043 ° C. and a V / III ratio of 2116. 4 (d) shows a growth temperature of 1043 ° C. and a V / III ratio of 3174, FIG. 4 (e) shows a growth temperature of 1083 ° C. and a V / III ratio of 1058, and FIG. 4 (f) shows a growth temperature of 1083 ° C. and a V / III ratio. It is 3174.

In FIGS. 4 (a) to 4 (c) and 4 (e), the surface of the light emitting layer 13 has a concave-convex shape in which bowl-shaped convex portions 20 are two-dimensionally distributed, and FIGS. 4 (d) and 4 (f). ), The surface of the light emitting layer 13 had a terrace-like uneven shape. As a result, in order to make the surface shape of the light emitting layer 13 a concave-convex shape in which the bowl-shaped convex portions 20 are two-dimensionally distributed, the growth temperature is T (° C.) and the V / III ratio is R, and 20T + R ≦ 24000. It turns out that it is necessary to meet. It was also found that the growth temperature should be 1100 ° C. or lower. It is considered that the lower limit of the growth temperature may be 850 ° C. or higher from the viewpoint of the crystallinity of n-AlGaN. It was also found that the V / III ratio should be in the range of 500 to 3200.

FIG. 5 is a photograph showing the emission intensity distribution of the light emitting layer 13. In FIG. 5, the higher the emission intensity, the brighter it is shown. As shown in FIG. 5, it can be seen that a plurality of black dots are distributed. This corresponds to the position of the dislocation.

FIG. 6 shows a CL image of the light emitting layer 13. In FIG. 6, the region where the Al composition of the light emitting layer 13 is high is shown brighter. As shown in FIG. 6, a plurality of circular white areas can be seen. This region is near the center of the convex portion 20. That is, the circular white region corresponds to the high energy region 22 of the first embodiment.

Further, from the dislocation distribution in FIG. 5 and the distribution of the convex portion 20 in FIGS. 4 and 6, the convex portion 20 is a spiral crystal growth of n-AlGaN centered on the spiral dislocation 21, and is near the center of the convex portion 20. It is presumed that there is a spiral dislocation 21 in the area, and a high energy region 22 exists around the spiral dislocation 21.

FIG. 7 is a graph showing the current-light output characteristics of the light emitting device of the first embodiment. The growth conditions of the n-contact layer 12 were changed as follows. In Example 1-1, the growth temperature was 1013 ° C. and the V / III ratio was 1058. In Example 1-2, the growth temperature of the n-contact layer 12 was 1043 ° C., and the V / III ratio was 1058. In Comparative Example 1, the growth temperature was 1173 ° C. and the V / III ratio was 1058.

As shown in FIG. 7, it was found that the light emitting element of Example 1 had a significantly improved light output as compared with the light emitting element of Comparative Example 1. It was also found that the lower the growth temperature of the n-contact layer 12, the higher the light output.

FIG. 8 is a graph showing the relationship between the resistivity of n-AlGaN having an Al composition of 62% and the Si concentration. The growth temperature of n-AlGaN was set to 3 patterns of 1173 ° C., 1043 ° C. and 1013 ° C.

As shown in FIG. 8, the resistivity decreases until the Si concentration reaches a certain value regardless of the growth temperature, and the resistivity starts to increase when the Si concentration exceeds a certain value. Met. At 1173 ° C., the resistivity was the minimum when the Si concentration was 6 × 10 ¹⁸ / cm ³ , and the resistivity at that time was 2 × 10 ⁻² Ω · cm. Further, in the case of 1043 ° C. ^{, the resistivity was the minimum when the Si concentration was 2 × 10 19} / cm ³ , and the resistivity at that time was 7 × 10 ^-3 Ω · cm. Further, in the case of 1013 ° C. ^{, the resistivity was the minimum when the Si concentration was 3 × 10 19} / cm ³ , and the resistivity at that time was 3 × 10 ^-3 Ω · cm. As described above, it was found that the lower the growth temperature, the higher the Si concentration at which the resistivity is minimized.

From this result, it was found that the resistivity of the n-contact layer 12 can be reduced by setting the Si concentration to an appropriate value according to the growth temperature of the n-contact layer 12. Therefore, if the surface shape of the n-contact layer 12 is set to a range in which the bowl-shaped convex portions 20 are two-dimensionally distributed in a concavo-convex shape with respect to the growth temperature, and the Si concentration is set to an appropriate range at the growth temperature, the luminous efficiency is improved. It was found that it is possible to reduce the resistance while improving it.

9A and 9B are STEM images of the convex portion 20 of n-AlGaN, FIG. 9A is a BF-STEM image, and FIG. 9B is a HAADF-STEM image. The Al composition of n-AlGaN is 62%, the growth temperature is 1013 ° C., and the V / III ratio is 1058. In FIG. 9, the heavier the element, the whiter it appears. That is, the more Ga, the whiter the image, and the more Al, the blacker the image.

As shown in FIG. 9A, it was found that a dislocation (spiral dislocation) extending in the vertical direction exists in the center of the convex portion 20. It was also found that there are many dislocations extending in the diagonal direction (composite dislocations) and dislocations extending in the lateral direction (blade-shaped dislocations) in the vicinity of the spiral dislocations.

Further, as shown in FIG. 9B, it was found that there was almost no light and darkness near the center of the convex portion 20, and bright and dark stripes were seen outward in a region slightly distant from the center. From this, it was found that the convex portion 20 is formed by spiral growth. Further, since there was almost no light and darkness in the horizontal direction, it was found that the spiral growth was a step flow growth, and the growth was carried out while taking in Ga in the step, and therefore the segregation of Ga was small.

(Modification example)
Although the light emitting element of Example 1 was a flip-chip type element, the present invention can also be applied to a face-up type element and a vertical type element that conducts conduction in the vertical direction.

The light emitting element of the present invention is not limited to the layer structure of the light emitting element of the first embodiment, and can be applied to a light emitting element having an arbitrary structure as long as it has a structure in which an n layer, a light emitting layer, and a p layer are laminated in this order.

The light emitting device of the present invention may have any wavelength as long as it emits ultraviolet light, but is suitable for UVB to UVC (wavelength 200 to 350 nm). In particular, it has been difficult to improve the luminous efficiency of a UVC band light emitting device having a wavelength of 300 nm or less, but according to the present invention, this is possible.

The light emitting device of the present invention can be used for sterilization, lighting, resin curing and the like.

10: Substrate 11: Buffer layer 12: n contact layer 13: Light emitting layer 14: Electronic block layer 15: p contact layer 16: Transparent electrode 17: p electrode 18: n electrode 20: Convex part 21: Spiral dislocation 22: High energy region

Claims (9)

In an ultraviolet light emitting device made of a group III nitride semiconductor having an n-layer, a light-emitting layer located on the n-layer, and a p-layer located on the light-emitting layer.
The n-layer surface and the light-emitting layer surface have a concave-convex shape in which bowl-shaped convex portions are two-dimensionally distributed.
A spiral dislocation or a compound dislocation exists near the center of the convex portion, and the region near the spiral dislocation or the compound dislocation has a higher bandgap energy than the other regions.
A light emitting element characterized by this. The height of the convex portion is 2 to 10 nm, and the diameter of the convex portion is 100 to 2000 nm.
The average roughness of the n-layer surface and the light-emitting layer surface is 2 to 10 nm.
The light emitting element according to claim 1. The light emitting element according to claim 1 or 2, wherein the density of the convex portion is 1 × 10 ⁶ to 1 × 10 ⁸ / cm ^2. The light emitting device according to any one of claims 1 to 3, wherein the Si concentration of the n layer is 1 × 10 ^{19 to} 5 × 10 ¹⁹ / cm ^3. In a method for manufacturing an ultraviolet light emitting device made of a group III nitride semiconductor having an n-layer, a light-emitting layer located on the n-layer, and a p-layer located on the light-emitting layer.
The n-layer is formed under the conditions that the growth temperature is 850 to 1100 ° C., the V / III ratio is 500 to 3200, the growth temperature is T (° C.), and the V / III ratio is R, and 20T + R ≦ 24000 is satisfied. As a result, the surface of the n-layer and the surface of the light-emitting layer are formed into a concavo-convex shape in which bowl-shaped convex portions are two-dimensionally distributed, and spiral dislocations or composite dislocations are present near the center of the convex portions, and the spiral dislocations or composite dislocations are present. Make sure that the region near the dislocation has a higher band gap energy than the other regions.
A method for manufacturing a light emitting element. The method for manufacturing a light emitting device according to claim 5, wherein the formation of the n-layer has a growth temperature of 1000 to 1050 ° C. and a V / III ratio of 1050 to 2200. The height of the convex portion is 2 to 10 nm, and the diameter of the convex portion is 100 to 2000 nm.
The average roughness of the n-layer surface and the light-emitting layer surface is 2 to 10 nm.
The method for manufacturing a light emitting element according to claim 5 or 6, wherein the light emitting element is manufactured. The method for manufacturing a light emitting element according to any one of claims 5 to 7, wherein the density of the convex portion is 1 × 10 ⁶ to 1 × 10 ⁸ / cm ^2. The method for manufacturing a light emitting device according to any one of claims 5 to 8, wherein the Si concentration of the n layer is 1 × 10 ^{19 to} 5 × 10 ¹⁹ / cm ^3.