JP7200068B2 - Light emitting device and manufacturing method thereof - Google Patents

Description

The present invention relates to a light-emitting device comprising a group III nitride semiconductor, and more particularly to a light-emitting device emitting ultraviolet light. The present invention also relates to a method for manufacturing the light emitting device.

Patent Document 1 discloses 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-tiered terrace, and a group III nitride semiconductor is step-flow-grown on the substrate to form a multi-tiered terrace of a light-emitting layer. By forming the light-emitting layer into such a shape, Ga is segregated in the step portion, thereby improving the light output.

WO2017/013729

However, even if the light-emitting layer has a multi-tiered terrace shape as in Patent Document 1, the ratio of Ga segregation is small, and the light output is not sufficiently improved. Moreover, in Patent Document 1, there are also problems that the light emitting layer does not emit light uniformly in the plane and that the resistance is not sufficiently reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to realize a light-emitting device that emits ultraviolet light and is made of a group III nitride semiconductor with high light-emitting efficiency.

The present invention provides an ultraviolet light-emitting element composed of a Group III nitride semiconductor having an n-layer, a light-emitting layer positioned on the n-layer, and a p-layer positioned on the light-emitting layer, wherein the n-layer and the light-emitting layer is composed of a group III nitride semiconductor containing Al and Ga, and the surface of the n-layer and the light-emitting layer has an uneven shape in which bowl-shaped protrusions are distributed two-dimensionally. A light-emitting device characterized in that a screw dislocation or compound dislocation exists, and a region in the vicinity of the screw dislocation or compound dislocation has a higher bandgap energy than other regions and acts as a potential barrier to carriers. be.

It is preferable that the height of the projections is 2 to 10 nm, the diameter of the projections is 100 to 2000 nm, and the average roughness of the n-layer surface and the light-emitting layer surface is 2 to 10 nm. Within this range, 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, luminous efficiency can be further improved.

The Si concentration of the n-layer is preferably 1×10 ¹⁹ to 5×10 ¹⁹ /cm ³ . It is possible to reduce the resistance of the light emitting element.

The present invention also provides a method for manufacturing an ultraviolet light-emitting device made of a Group III nitride semiconductor having an n-layer, a light-emitting layer positioned on the n -layer, and a p-layer positioned on the light-emitting layer, The layer and the light-emitting layer are made of a group III nitride semiconductor containing Al and Ga . The surface of the n-layer and the surface of the light-emitting layer are formed under the conditions satisfying 20T+R≦24000, where R is the V/III ratio. A light-emitting device characterized in that screw dislocations or compound dislocations are present in the region, and a region in the vicinity of the screw dislocations or compound dislocations has a higher bandgap energy than other regions and serves as a potential barrier to carriers. is a manufacturing method.

The n-layer is preferably formed at a growth temperature of 1000-1050° C. and a V/III ratio of 1050-2200. Luminous efficiency can be further improved.

According to the present invention, since the vicinity of the center of the projection has a high Al composition, a potential barrier is formed against carriers, and the carriers are not trapped by screw dislocations or composite dislocations at the center of the projection, or other dislocations in the vicinity thereof. , the luminous efficiency can be improved.

1A and 1B are diagrams showing a configuration of a light-emitting element of Example 1. FIG. FIG. 4 is a diagram schematically showing surface shapes of an n-contact layer 12 and a light-emitting layer 13; The figure which showed typically the energy band diagram of convex part 20 vicinity. An AFM image of the surface of the light-emitting layer 13 . FIG. 3 is a diagram showing a light emission intensity distribution of a light emitting layer 13; FIG. 4 is a diagram showing a CL image of a light-emitting layer 13; 4 is a graph showing current-light output characteristics of the light-emitting device of Example 1. FIG. 4 is a graph showing the relationship between the resistivity of n-AlGaN and the Si concentration; A STEM image near the convex portion 20 .

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

FIG. 1 is a diagram showing the configuration of a light-emitting device of Example 1. FIG. The light-emitting device of Example 1 is a flip-chip type ultraviolet light-emitting device, and includes a substrate 10, a buffer layer 11, an n-contact layer 12, a light-emitting layer 13, an electron blocking layer 14, 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 invention, and the electron blocking layer 14 and the p-contact layer 15 correspond to the p-layer of the invention.

(Composition of each layer)
First, the structure of each layer of the light emitting device of Example 1 will be described.

The substrate 10 is a growth substrate made of sapphire. The thickness is, for example, 900 μm. Besides sapphire, AlN, Si, SiC, ZnO, etc. can be used.

A buffer layer 11 is located on the substrate 10 . The buffer layer 11 has a structure in which three layers of a nucleus layer, a low-temperature buffer layer, and a high-temperature buffer layer are laminated in order. The nucleus layer is composed of non-doped AlN grown at a low temperature and serves as a nucleus for crystal growth. The thickness of the nucleus 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 nucleus 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 threading dislocations of AlN is reduced.

N-contact layer 12 is located on 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 in luminous efficiency and the reduction in resistance of the light emitting element of Example 1 can be achieved. As an example of the structure 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 .

Light-emitting layer 13 is located on n-contact layer 12 . The light emitting layer 13 has an MQW structure with 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 the 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 structure 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 blocking layer 14 is located on the light emitting layer 13 . The electron blocking layer 14 is made of p-AlGaN having a higher Al composition than the third barrier layer. The electron blocking layer 14 prevents electrons from diffusing to the p-contact layer 15 side. As an example of the configuration of the electron blocking layer 14, the Al composition is 80%, the thickness is 25 nm, and the Mg concentration is 5×10 ¹⁹ /cm ³ .

A p-contact layer 15 is located on the electron blocking 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 order. The first p-contact layer and the second p-contact layer are made of p-GaN. As an example of the configuration of the first p-contact layer, the thickness is 700 nm and the Mg concentration is 2×10 ¹⁹ /cm ³ . Also, 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 partial region of the surface of the p-contact layer 15 . The trench penetrates the p-contact layer 15 and the light-emitting layer 13 and has a depth reaching the n-contact layer. This groove is for providing the n-electrode 18 .

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

A 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 at the bottom of the trench. The n-electrode 18 is Ti/Al/Ni, V/Al/Ni, V/Al/Ru, or the like.

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

The surface of the n-contact layer 12 has an uneven shape in which bowl-shaped protrusions 20 are two-dimensionally distributed (see FIG. 2). Also, the surface of the n-contact layer 12 is less uneven 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 protrusion 20 exists corresponding to the position of the screw dislocation, and the screw dislocation 21 exists near the center of the protrusion 20 . This is because the protrusions 20 are formed by spirally growing crystals around the screw dislocations 21 . Therefore, the density of the protrusions 20 approximately matches the density of screw dislocations. The screw dislocation 21 may be a compound dislocation of a screw dislocation and an edge dislocation. In the following description, the screw dislocation 21 also includes the compound dislocation. In addition, many edge dislocations and compound dislocations (compound dislocations of screw dislocations and edge dislocations) are also present in the convex portion 20 .

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

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

The region near the center of the projection 20 (the region near the screw dislocation 21) has a higher Al composition than the other region 23 of the n-contact layer 12, or has a higher bandgap energy than the other region 23 due to crystal strain. There is an increased high energy region 22 . The high-energy region 22 is approximately circular in plan view and has a diameter of 100 to 1000 nm centered on the screw dislocation 21 . The bandgap energy of high energy region 22 is, for example, 4.4 to 5 eV, and the bandgap energy difference between high energy region 22 and 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 protrusions 20 are two-dimensionally distributed, and the screw dislocations 21 are present near the center of the protrusions 20, and the high-energy regions 22 are present in the vicinity of the screw dislocations 21. ing. The height H, diameter R, and density of the projections 20 and the average roughness of the surface of the light emitting layer 13 are also the same as those of the surface of the n-contact layer 12 .

In the light-emitting element of Example 1, the surface shape of the light-emitting layer 13 is set as described above, so that the light-emitting efficiency is improved. The reason will be explained based on 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, showing the vicinity of the convex portion 20. As shown in FIG. Screw dislocations 21 are present near the center of the bowl-shaped protrusion 20 . The screw dislocation 21 forms a trap level, and carriers trapped therein are non-radiatively coupled. Therefore, the screw dislocations 21 are a factor in lowering the luminous efficiency.

In the light emitting device of Example 1, the high energy region 22 is formed around the screw dislocation 21 and has a higher bandgap energy than the other region 23 of the light emitting layer 13 . Therefore, the high energy region 22 forms a potential barrier against carriers. Due to the presence of this potential barrier, the number of carriers trapped by the screw dislocation 21 and other dislocations existing in the vicinity of the screw dislocation 21 is reduced, and non-radiative coupling is also reduced. In addition, the number of carriers radiatively coupled in the other region 23 of the light-emitting layer 13 increases accordingly. In this way, the luminous efficiency is improved due to the decrease in carriers trapped by the screw dislocation 21 and other dislocations in the vicinity thereof and the increase in radiatively coupled carriers.

As described above, in the light emitting device of Example 1, the surface shape of the light emitting layer 13 is an uneven shape in which the bowl-shaped protrusions 20 are two-dimensionally distributed, and the screw dislocations 21 are present near the centers of the protrusions 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 for manufacturing the light emitting device of Example 1 will be described. The MOCVD method is used for crystal growth of the Group III nitride semiconductor, and ammonia is used as a nitrogen source, trimethylgallium as a Ga source, and trimethylaluminum as an Al source. Silane is used as an n-type dopant gas, and bis(cyclopentadienyl)magnesium is used as a p-type dopant gas. Hydrogen and nitrogen are used as carrier gas.

First, a substrate 10 made of sapphire is prepared. Then, a buffer layer 11 is formed on the substrate 10 . In forming the buffer layer 11, first, a nucleation layer made of AlN is formed by sputtering. The growth temperature is 880° C., for example. Next, a low-temperature buffer layer and a high-temperature buffer layer made of AlN are sequentially formed on the nucleus layer by MOCVD. The growth conditions for the low-temperature buffer layer are, for example, a growth temperature of 1090° C. and a growth pressure of 5 kPa. The growth conditions for 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 MOCVD. The growth temperature is 850-1100° C., the V/III ratio is 500-3200, and the growth pressure is 2-20 kPa. Also, where T (° C.) is the growth temperature and R is the V/III ratio, 20T+R≦24000 is satisfied. By setting the growth temperature and the V/III ratio within these ranges, n-AlGaN can be spirally grown around the screw dislocation 21, and the spirally grown portion becomes the bowl-shaped protrusion 20. FIG. As a result, the surface shape of the n-contact layer 12 becomes an uneven shape in which the bowl-shaped protrusions 20 are two-dimensionally distributed. Moreover, this spiral growth is step-flow growth (growth in which the growth from the steps is more dominant than from the terraces), and Ga is incorporated in the steps. Therefore, the segregation of Ga in the in-plane direction is smaller than in the conventional case where the uneven shape is a multi-stage terrace shape. Further, by forming the protrusion 20 in this manner, a high energy region 22 can be formed around the screw dislocation 21 near the center of the protrusion 20 . The reason why the Al composition of the high-energy region 22 is high is that Al does not easily migrate and is easily trapped around dislocations. Conversely, there are more dislocations near the center of the projection 20 than in the other regions 23 .

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, the resistance of the n-contact layer 12 can be reduced while improving the luminous efficiency by making the surface shape of the n-contact layer 12 uneven.

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

Next, a light-emitting layer 13 is formed on the n-contact layer 12 by MOCVD. The light emitting layer 13 is formed by laminating a first barrier layer, a first well layer, a second barrier layer, a second well layer, and a third barrier layer in this order. The growth conditions for 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 becomes substantially the same as the surface shape of the n-contact layer 12 . That is, the bowl-shaped protrusions 20 are two-dimensionally distributed, and have a high-energy region 22 around the screw dislocations 21 near the center of the protrusions 20 .

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

Next, a p-contact layer 15 is formed on the electron blocking layer 14 by MOCVD. 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 for the first p-contact layer are, for example, a growth temperature of 1050° C. and a growth pressure of 20 kPa. The growth conditions for 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 of the surface of the p-contact layer 15 is dry-etched to form a groove reaching the n-contact layer 12 .

Next, a transparent electrode 16 is formed on the p-contact layer 15 . Next, a p-electrode 17 is formed on the transparent electrode 16, and an n-electrode is formed on the n-contact layer 12 exposed at the bottom of the groove. The transparent electrode 16, p-electrode 17, and n-electrode 18 are formed by sputtering, vapor deposition, or the like. The light emitting element of Example 1 is manufactured by the above.

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

FIG. 4 is an AFM image of the surface of the light-emitting layer 13 . FIG. 4(a) shows growth temperature of 1013° C., V/III ratio of 1587, FIG. 4(b) shows growth temperature of 1013° C., V/III ratio of 3174, FIG. 4(c) shows growth temperature of 1043° C., V/III ratio of 2116. 4(d) shows growth temperature of 1043° C. and V/III ratio of 3174; FIG. 4(e) shows growth temperature of 1083° C. and V/III ratio of 1058; FIG. 4( f) shows growth temperature of 1083° C. and V/III ratio 3174.

4(a) to (c) and (e), the surface of the light emitting layer 13 has an uneven shape in which bowl-shaped convex portions 20 are distributed two-dimensionally. ), the surface of the light-emitting layer 13 had a terraced uneven shape. As a result, in order to make the surface shape of the light-emitting layer 13 an uneven shape in which the bowl-shaped protrusions 20 are two-dimensionally distributed, the growth temperature is T (° C.) and the V/III ratio is R, where 20T+R≦24000. It was found necessary to satisfy Also, it was found that the growth temperature should be 1100° C. or lower. Regarding the lower limit of the growth temperature, it is considered that 850° C. or higher is sufficient from the viewpoint of the crystallinity of n-AlGaN. It was also found that the V/III ratio should be in the range of 500-3200.

FIG. 5 is a photograph showing the emission intensity distribution of the light emitting layer 13. As shown in FIG. In FIG. 5, the higher the emission intensity, the brighter the light. 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. FIG. In FIG. 6, the higher the Al composition of the light-emitting layer 13, the brighter the area. As shown in FIG. 6, a plurality of circular white areas can be seen. This area is near the center of the convex portion 20 . That is, the circular white area corresponds to the high energy area 22 of the first embodiment.

Further, from the dislocation distribution in FIG. 5 and the distribution of the projections 20 in FIGS. It is presumed that a screw dislocation 21 exists in the region and a high energy region 22 exists around the screw dislocation 21 .

FIG. 7 is a graph showing current-light output characteristics of the light-emitting device of Example 1. FIG. 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 1,043° C. and the V/III ratio was 1,058. 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 output of the light emitting device of Example 1 was significantly improved as compared with the light emitting device of Comparative Example 1. It was also found that the lower the growth temperature of the n-contact layer 12, the more the optical output is improved.

FIG. 8 is a graph showing the relationship between the resistivity of n-AlGaN with an Al composition of 62% and the Si concentration. Three patterns of 1173° C., 1043° C., and 1013° C. were used as the n-AlGaN growth temperature.

As shown in FIG. 8, regardless of the growth temperature, the resistivity decreases up to a certain value of Si concentration, and when it exceeds a certain value, the resistivity turns to increase, and the characteristic that draws a downward convex curve. Met. At 1173° C., the resistivity was minimized when the Si concentration was 6×10 ¹⁸ /cm ³ , and the resistivity at that time was 2×10 ⁻² Ω·cm. At 1043° C., the resistivity was minimized when the Si concentration was 2×10 ¹⁹ /cm ³ , and the resistivity at that time was 7×10 ⁻³ Ω·cm. At 1013° C., the resistivity was minimized when the Si concentration was 3×10 ¹⁹ /cm ³ , and the resistivity at that time was 3×10 ⁻³ Ω·cm. Thus, 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 adjusting 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 surface shape of the n-contact layer 12 is in a range in which the bowl-shaped protrusions 20 are two-dimensionally distributed, and the Si concentration is set to an appropriate range at the growth temperature, the luminous efficiency can be improved. It was found that the resistance can be lowered while improving the resistance.

9A and 9B are STEM images of the n-AlGaN protrusions 20, FIG. 9A being a BF-STEM image, and FIG. 9B being a HAADF-STEM image. The n-AlGaN has an Al composition of 62%, a growth temperature of 1013° C., and a V/III ratio of 1058. In FIG. 9, heavier elements appear whiter. That is, the more Ga, the whiter the image, and the more Al, the blacker the image.

As shown in FIG. 9( a ), it was found that a vertically extending dislocation (screw dislocation) was present in the center of the protrusion 20 . It was also found that there are many dislocations extending in an oblique direction (compound dislocations) and dislocations extending in a lateral direction (edge dislocations) in the vicinity of screw dislocations.

Moreover, as shown in FIG. 9(b), there is almost no contrast in the vicinity of the center of the projection 20, and a striped pattern of contrast can be seen toward the outside in a region slightly away from the center. From this, it was found that the convex portion 20 was formed by spiral growth. In addition, since there is almost no contrast in the horizontal direction, it was found that the spiral growth is step-flow growth, and the growth takes place while taking Ga in the steps, so that the segregation of Ga is small.

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

The light-emitting device of the present invention is not limited to the layer structure of the light-emitting device of Example 1, and can be applied to a light-emitting device having any structure as long as it has a structure in which an n-layer, a light-emitting layer, and a p-layer are laminated in order.

The light-emitting element of the present invention may emit ultraviolet light at any wavelength, but is suitable for UVB to UVC (wavelength 200 to 350 nm). In particular, it has been difficult to improve the luminous efficiency of light-emitting elements in the UVC band with a wavelength of 300 nm or less, but the present invention makes it possible.

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

10: substrate 11: buffer layer 12: n-contact layer 13: light emitting layer 14: electron blocking layer 15: p-contact layer 16: transparent electrode 17: p-electrode 18: n-electrode 20: convex portion 21: screw dislocation 22: high energy region

Claims (9)

An ultraviolet emitting 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 and the light-emitting layer are made of a group III nitride semiconductor containing Al and Ga,
The n-layer surface and the light-emitting layer surface have an uneven shape in which bowl-shaped protrusions are two-dimensionally distributed,
A screw dislocation or composite dislocation is present near the center of the protrusion, and a region near the screw dislocation or composite dislocation has a higher bandgap energy than other regions and acts as a potential barrier against carriers.
A light emitting device characterized by: The height of the convex portion is 2 to 10 nm , 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 device according to claim 1, characterized in that: 3. The light-emitting device according to claim 1, wherein the density of said protrusions is 1×10 ⁶ to 1×10 ⁸ /cm ² . 4. The light-emitting device according to claim 1, wherein the n-layer has a Si concentration of 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 positioned on the n-layer, and a p-layer positioned on the light-emitting layer,
The n-layer and the light-emitting layer are made of a group III nitride semiconductor containing Al and Ga,
The n-layer is formed at a growth temperature of 850 to 1100° C., a V/III ratio of 500 to 3200, a growth temperature of T (° C.), a V/III ratio of R, and satisfying 20T+R≦24000. Thus, the surface of the n-layer and the surface of the light-emitting layer have an uneven shape in which bowl-shaped protrusions are two-dimensionally distributed, screw dislocations or compound dislocations are present near the centers of the protrusions, and the screw dislocations or compound dislocations so that the region near the dislocation has a higher bandgap energy than other regions and acts as a potential barrier to carriers ;
A method for manufacturing a light-emitting device, characterized by: 6. The method according to claim 5, wherein the n-layer is formed at a growth temperature of 1000-1050.degree. C. and a V/III ratio of 1050-2200. The height of the convex portion is 2 to 10 nm , 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.
7. The method of manufacturing a light-emitting device according to claim 5 or 6, characterized in that: 8. The method of manufacturing a light-emitting device according to claim 5, wherein the density of the protrusions is 1×10 ⁶ to 1×10 ⁸ /cm ² . 9. The method of manufacturing a light-emitting device according to claim 5, wherein the n-layer has a Si concentration of 1×10 ¹⁹ to 5×10 ¹⁹ /cm ³ .

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