Group III nitride semiconductor light-emitting element and method for manufacturing the same

Abstract

Provided are a group-III nitride semiconductor light-emitting element having a more excellent light-emitting output than ever before and a method for manufacturing the same. The light-emitting wavelength of the group-III nitride semiconductor light-emitting element of the present invention is 200 to 350 nm, and it sequentially has an n-type semiconductor layer, a light-emitting layer, an AlN guiding layer, an electron blocking layer, and a p-type semiconductor layer. The light-emitting layer is formed by alternately laminating a barrier layer and a well layer N layers in sequence (where N is an integer). The aforementioned electron blocking layer is p-type Al z Ga 1‑z N (0.50 ≤ z ≤ 0.80), and the aforementioned barrier layer is n-type Al b Ga 1‑b N (z + 0.01 ≤ b ≤ 0.95).

Description

Technical Field

[0001] The present invention relates to a group-III nitride semiconductor light-emitting element and a method for manufacturing the same, and more particularly to a group-III nitride semiconductor light-emitting element having excellent light emission output and a method for manufacturing the same. Background Art

[0002] Conventionally, group-III nitride semiconductors formed of compounds of group-III elements such as Al, Ga, In and N have been used as materials for light-emitting elements emitting blue light to deep ultraviolet light. Among them, group-III nitride semiconductors formed of AlGaN having a high Al composition ratio are used for deep ultraviolet light-emitting elements (DUV-LEDs) having a light emission wavelength of 200 to 350 nm.

[0003] Generally speaking, it is said that the light emission efficiency of deep ultraviolet light-emitting elements using group-III nitride semiconductors is extremely low, and it is difficult to achieve high output. In order to realize a deep ultraviolet light-emitting element having a small size and a high output, various attempts have been made to achieve high light extraction efficiency, low resistance characteristics, etc. in addition to improving the internal quantum efficiency.

[0004] As such a deep ultraviolet light-emitting layer, a group-III nitride semiconductor light-emitting element 1 having an n-type semiconductor layer 3, a light-emitting layer 4 formed by alternately laminating a barrier layer 4b and a well layer 4w, an electron blocking layer 6, and a p-type semiconductor layer 7 in this order is known. A part of the band structure of the group-III nitride semiconductor light-emitting element 1 is shown in Figure 1A . As shown in Figure 1A , conventionally, the Al composition ratio of the electron blocking layer 6 is usually made higher than the Al composition ratio of the barrier layer 4b.

[0005] For example, Patent Document 1 discloses a nitride semiconductor light-emitting element having a light emission wavelength of 200 to 350 nm, in which, with respect to the Al composition ratio (a) of the barrier layer of the light-emitting layer, the Al composition ratio (b) of the p-type cladding layer is 0.1 < b - a ≤ 0.45, and the Al composition ratio (c) of the electron blocking layer is 0.11 ≤ c - a ≤ 0.98. According to Patent Document 1, by setting the relationship of such Al composition ratios, the light emission output of the nitride semiconductor light-emitting element can be increased.

[0006] In addition, the present applicant proposed in Patent Document 2 a group-III nitride semiconductor light-emitting element 1', which improves the reliability and light emission output of the element by providing an AlN guiding layer 5 having a specified thickness between the light-emitting layer 4 and the electron blocking layer 6 of the above-mentioned group-III nitride semiconductor light-emitting element 1 (refer to the band structure of Figure 1B ).

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-241397

[0010] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2017-34036 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] In recent years, there has been an increasing desire to improve the light emission output of deep ultraviolet light-emitting elements (DUV-LEDs), and further improvements are expected.

[0013] Therefore, an object of the present invention is to provide a group III nitride semiconductor light-emitting element having excellent light emission output and a method for manufacturing the same.

[0014] Solutions for Solving the Problems

[0015] The present inventors have conducted in-depth research on a method for increasing the light emission output when an AlN guiding layer 5 is provided between a light-emitting layer 4 and an electron blocking layer 6 as in Patent Document 2 described above. And it has been found that: in the case of providing the AlN guiding layer 5, contrary to the usual relationship between the Al composition ratios between the barrier layer and the electron blocking layer ([Al composition ratio of the barrier layer] < [Al composition ratio of the electron blocking layer]), when the Al composition ratio of the barrier layer is intentionally made larger than the Al composition ratio of the electron blocking layer, excellent light emission output can be obtained, and thus the present invention has been completed.

[0016] That is, the gist of the present invention is constituted as follows.

[0017] (1) A group III nitride semiconductor light-emitting element, which is a group III nitride semiconductor light-emitting element having a light emission wavelength of 200 to 350 nm, characterized in that

[0018] it sequentially has an n-type group III nitride semiconductor layer, a group III nitride semiconductor light-emitting layer, an AlN guiding layer, an electron blocking layer, and a p-type group III nitride semiconductor layer, and the group III nitride semiconductor light-emitting layer is formed by alternately laminating N layers (where N is an integer) of a barrier layer and a well layer having a band gap smaller than that of the aforementioned barrier layer in sequence,

[0019] the aforementioned electron blocking layer is p-type Al z Ga 1-z N (0.50 ≤ z ≤ 0.80),

[0020] the aforementioned barrier layer is n-type Al b Ga 1-b N (z + 0.01 ≤ b ≤ 0.95).

[0021] (2) The group-III nitride semiconductor light-emitting element according to (1) above, wherein the Al composition ratio (b) of the barrier layer is b ≤ z + 0.20.

[0022] (3) The group-III nitride semiconductor light-emitting element according to (1) or (2) above, wherein the thickness of the AlN guiding layer is 0.5 nm or more and 2.0 nm or less.

[0023] (4) The group-III nitride semiconductor light-emitting element according to any one of (1) to (3) above, wherein the well layer of the Nth layer in the group-III nitride semiconductor light-emitting layer is in contact with the AlN guiding layer; or,

[0024] a final barrier layer having an Al composition ratio greater than or equal to that of the barrier layer and less than that of the AlN guiding layer is provided between the well layer of the Nth layer in the group-III nitride semiconductor light-emitting layer and the AlN guiding layer, and the thickness of the final barrier layer is 1.5 nm or less.

[0025] (5) A method for manufacturing a group-III nitride semiconductor light-emitting element, characterized in that it is a method for manufacturing a group-III nitride semiconductor light-emitting element having a light emission wavelength of 200 to 350 nm, and includes the following steps:

[0026] The first step of forming an n-type group-III nitride semiconductor layer;

[0027] The second step of alternately laminating the barrier layer and the well layer having a band gap smaller than that of the barrier layer N times (where N is an integer) on the n-type group-III nitride semiconductor layer to form a group-III nitride semiconductor light-emitting layer;

[0028] The third step of forming an AlN guiding layer on the group-III nitride semiconductor light-emitting layer;

[0029] The fourth step of forming an electron blocking layer on the AlN guiding layer; and,

[0030] The fifth step of forming a p-type semiconductor layer on the electron blocking layer, wherein,

[0031] the electron blocking layer is made of p-type Al z Ga 1-z N (0.50 ≤ z ≤ 0.80),

[0032] the barrier layer is made of n-type Al b Ga 1-b N (z + 0.01 ≤ b ≤ 0.95).

[0033] Effects of the Invention

[0034] According to the present invention, it is possible to provide a group-III nitride semiconductor light-emitting element having a light output more excellent than that of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A FIG. is an example showing a part of the band structure of a conventionally known group-III nitride semiconductor light-emitting element.

[0036] Figure 1B FIG. is another example showing a part of the band structure of a conventionally known group-III nitride semiconductor light-emitting element.

[0037] Figure 2 FIG. is a schematic cross-sectional view illustrating a group-III nitride semiconductor light-emitting element according to an embodiment of the present invention.

[0038] Figure 3A FIG. is a diagram showing a part of the band structure of one mode of the group-III nitride semiconductor light-emitting element according to the present invention.

[0039] Figure 3B FIG. is a diagram showing a part of the band structure of another mode of the group-III nitride semiconductor light-emitting element according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] Before describing the embodiments according to the present invention, the following will be described in advance. First, in this specification, when only "AlGaN" is marked without giving the Al composition ratio, it means an arbitrary compound in which the chemical composition ratio of group-III elements (the sum of Al and Ga) to N is 1:1, and the ratio of group-III element Al to Ga is not fixed. At this time, even if there is no mark regarding In as a group-III element, it means that 5% or less of In can be contained with respect to Al and Ga as group-III elements. In addition, when only "AlN" or "GaN" is marked, it means that Ga and Al are not included in the composition ratio, but by only marking "AlGaN", neither AlN nor GaN is excluded. It should be noted that the value of the Al composition ratio can be measured by photoluminescence measurement, X-ray diffraction measurement, etc.

[0041] In addition, in this specification, a group-III nitride semiconductor layer that electrically functions as a p-type layer is sometimes simply referred to as a p-type layer, and a group-III nitride semiconductor layer that electrically functions as an n-type layer is sometimes simply referred to as an n-type layer. On the other hand, when no specific impurities such as Mg and Si are deliberately added and it does not electrically function as a p-type or n-type layer, it is called "i-type" or "undoped". The undoped layer may contain inevitable impurities during the manufacturing process. Specifically, the carrier density is small (for example, less than 4×10 16 / cm3 ) In this case, it is referred to as "undoped" in this specification. In addition, the values of impurity concentrations such as Mg and Si are the values obtained by SIMS analysis.

[0042] In addition, the total thickness of each layer formed by epitaxial growth can be measured using an optical interference film thickness measuring instrument. In addition, for the thickness of each layer, when the composition ratios of adjacent layers are significantly different (for example, when the difference in Al composition ratio is more than 0.01), it can be calculated based on the cross-sectional observation of the growth layer by a transmission electron microscope. In addition, for the boundary and thickness of layers with the same or substantially the same Al composition ratio (for example, less than 0.01) but different impurity concentrations in adjacent layers, the boundary between the two and the thickness of each layer are the values obtained based on TEM-EDS measurement. In addition, the impurity concentrations of the two can be measured by SIMS analysis. In addition, when the thickness of each layer is relatively thin as in the superlattice structure, TEM-EDS can be used to measure the thickness.

[0043] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the same reference numerals are generally assigned to the same components, and the description thereof is omitted. In addition, in each figure, for convenience of explanation, the horizontal and vertical ratios of the substrate and each layer are shown exaggerated compared to the actual ratios.

[0044] (Group-III Nitride Semiconductor Light-Emitting Element)

[0045] As Figure 2 shown, the group-III nitride semiconductor light-emitting element 100 according to an embodiment of the present invention sequentially includes: an n-type group-III nitride semiconductor layer 30, a group-III nitride semiconductor light-emitting layer 40 formed by alternately laminating N layers (where N is an integer) of a barrier layer 40b and a well layer 40w having a bandgap smaller than that of the barrier layer 40b, an AlN guiding layer 50, an electron blocking layer 60, and a p-type group-III nitride semiconductor layer 70. In this specification, the Al composition ratio of the barrier layer 40b is denoted as b, the Al composition ratio of the well layer 40w is denoted as w, and the Al composition ratio of the electron blocking layer 60 is denoted as z. In the group-III nitride semiconductor light-emitting element 100 according to the present invention, the Al composition ratio (b) of the barrier layer 40b is greater than the Al composition ratio (z) of the electron blocking layer 60. Hereinafter, in this specification, the n-type group-III nitride semiconductor layer 30 is abbreviated as "n-type layer 30", the group-III nitride semiconductor light-emitting layer 40 is abbreviated as "light-emitting layer 40", and the p-type group-III nitride semiconductor layer 70 is abbreviated as "p-type layer 70".

[0046] As Figure 2As shown, the n-type layer 30 of the group-III nitride semiconductor light-emitting element 100 can be provided on an AlN template substrate having an AlN layer 20 on the surface of a substrate 10. In addition, the group-III nitride semiconductor light-emitting element 100 can be provided with an n-type electrode 80 and a p-type electrode 90 formed on a p-type layer 70, and the n-type electrode 80 is formed on the n-type layer 30 exposed by removing a part of the light-emitting layer 40, the AlN guiding layer 50, the electron blocking layer 60, and the p-type layer 70 by etching or the like. The above-mentioned substrate 10, AlN layer 20, n-type electrode 80, and p-type electrode 90 can be formed into a conventional structure based on a generally known conventional group-III nitride semiconductor light-emitting element, and there is no particular limitation on the specific structure. In addition, although not shown, a buffer layer selected from one or more of an AlGaN layer, a composition-graded layer, and a superlattice layer can be provided between the AlN layer 20 and the n-type layer 30.

[0047] <n-type layer>

[0048] The n-type layer 30 is a group-III nitride semiconductor layer containing at least Al, and a conventional n-type semiconductor layer can be used as long as it functions as an n-type semiconductor layer in the group-III nitride semiconductor light-emitting element 100. The n-type layer 30 is formed of, for example, an AlGaN material, and in addition, it can contain In in an amount of 5% or less with respect to Al and Ga as group-III elements. The n-type layer 30 is doped with an n-type dopant (impurity), and examples of the n-type dopant include Si, Ge, Sn, S, O, Ti, Zr, etc. The doping concentration is not particularly limited as long as it can function as an n-type, and can be set to, for example, 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 . In addition, the Al content rate of the n-type layer 30 is not particularly limited and can be set to a general range. In addition to forming the n-type layer 30 into a structure composed of a single layer or multiple layers, it can also be formed into a structure including a composition-graded layer in which the composition ratio of group-III elements changes in the crystal growth direction and a superlattice structure. The n-type layer 30 not only forms a contact portion with the n-side electrode but also has a function of improving crystallinity from the substrate to the light-emitting layer.

[0049] <n-type guiding layer>

[0050] It should be noted that although in Figure 2Although not shown in the figure, an n-type guiding layer 35 may be provided between the light-emitting layer 40 and the n-type layer 30. The n-type guiding layer 35 is preferably made of an AlGaN material, and the Al composition ratio thereof is preferably set to be equal to or higher than the Al composition ratio of the aforementioned n-type layer 30 and lower than the Al composition ratio (b) of the barrier layer 40b. Its thickness can be set to 3 nm to 30 nm. In addition, in the n-type guiding layer 35, it is preferable to dope an n-type dopant (impurity) in the same manner as in the n-type layer, and the doping amount is preferably less than that of the n-type layer.

[0051] <Light-emitting layer>

[0052] In the group-III nitride semiconductor light-emitting element 100, the light-emitting layer 40 and the n-type layer 30 are arranged adjacent to each other. The light-emitting layer 40 is formed by alternately laminating the barrier layer 40b and the well layer 40w with a bandgap smaller than that of the barrier layer 40b, each N layers (where N is an integer). For example, as the barrier layer 40b and the well layer 40w, AlGaN materials with different Al composition ratios can be used. The barrier layer 40b and the well layer 40w can be made into an AlGaInN material or the like by introducing a group-III element such as In at a composition ratio within 5% as needed, and more preferably made into a ternary AlGaN material using only Al and Ga as the group-III elements. The well layer 40w can be made into either an n-type or an i-type, and the barrier layer 40b is made into an n-type. This is because: as the electron concentration increases, it has the effect of compensating for crystal defects in the well layer. It should be noted that the light-emitting layer 40 can be said to be equivalent to a layer obtained by removing the last barrier layer on the p-type semiconductor layer side from a general multiple quantum well (MQW: Multiple Quantum Well) structure in which the barrier layer 40b and the well layer 40w are repeatedly formed and clamped by the barrier layer 40b.

[0053] <<Barrier layer and well layer>>

[0054] Al b Ga 1-b N material can be used as the barrier layer 40b, and Al w Ga 1-w N material can be used as the well layer 40w. The Al composition ratio (b) of the barrier layer 40b can be set, for example, to 0.51 to 0.95, more preferably to 0.53 to 0.85, and the Al composition ratio (w) of the well layer 40w can be set, for example, to 0.30 to 0.80 (where w < b). In addition, the number of layers N of the barrier layer 40b and the well layer 40w can be set to a positive integer from 1 to 10, for example. Furthermore, the thickness of the barrier layer 40b can be set to 3 nm to 30 nm, and the thickness of the well layer 40w can be set to 0.5 nm to 5 nm.

[0055] Furthermore, the present inventors have found that: by making the Al composition ratio (b) of the barrier layer 40b greater than the Al composition ratio (z) of the electron blocking layer described later, and setting z + 0.01 ≤ b ≤ 0.95, a further improvement in the light emission output can be obtained. Furthermore, in order to ensure the effect of improving the light emission output, it is preferable to set the upper limit of the Al composition ratio (b) of the barrier layer 40b to z + 0.2 (b ≤ z + 0.2), more preferably to z + 0.17 (b ≤ z + 0.17), and particularly preferably to z + 0.15 (b ≤ z + 0.15). Particularly preferably, the Al composition ratio (b) of the barrier layer 40b is set to z + 0.05 ≤ b ≤ z + 0.15.

[0056] It should be noted that the center wavelength of the emitted light can be roughly adjusted by the Al composition ratio (w) of the well layer 40w. As the center wavelength of the light, it can be set to 200 to 350 nm, preferably 200 to 300 nm, and more preferably 270 to 295 nm. For example, if the Al composition ratio (w) of the well layer 40w in the light emitting layer 40 is set to 0.35 or more, the center wavelength of the light radiated from the light emitting layer 40 becomes 300 nm or less.

[0057] Here, Figure 3A 、 Figure 3B shows a mode of the band structure of the conduction band of the group III nitride semiconductor light emitting element 100 based on an embodiment of the present invention. Compared with the aforementioned conventionally known Figure 1B for comparison, the characteristic band structure of the present invention is described. As shown in the existing example of Figure 1B generally, for the electron blocking layer 60, compared with the Al composition ratio (b) of the barrier layer 40b, for example, Al z Ga 1-z N material (b < z < 1) is set to an Al composition ratio higher than that of the barrier layer, thereby making the band gap of the electron blocking layer greater than that of the barrier layer.

[0058] Compared with the Figure 1B band structure, in the Figure 3A based on the embodiment of the present invention, the Al composition ratio (b) of the barrier layer 40b has a structure with a band gap greater than that of the electron blocking layer 60. That is, the Al composition ratio (b) of the barrier layer 40b is made greater than the Al composition ratio (z) of the electron blocking layer 60 (see details later), satisfying the relationship of z + 0.01 ≤ b ≤ 0.95. Figure 3A For the case where the n-type guiding layer 35 has the same band gap as the barrier layer 40b, Figure 3B and for the case where the band gap of the n-type guiding layer 35 is different from that of the barrier layer 40b and the same as that of the n-type layer 30. In both cases, the Al composition ratio (b) of the barrier layer 40b is greater than the Al composition ratio (z) of the electron blocking layer 60.

[0059] The present inventors have confirmed through experiments that, based on the relationship between the band gaps of the barrier layer and the electron blocking layer of the present invention, a group-III nitride semiconductor light-emitting device with a more excellent light emission output than before can be achieved. Without being bound by theory, the present inventors consider the reasons for obtaining such an effect as follows. First, the AlGaN-based semiconductor material used as the material for DUV-LEDs has a large band gap, so it is difficult to achieve low resistance. In particular, it is difficult to increase the hole concentration in the p-type AlGaN layer. Therefore, at the electrode portion, the contact resistance increases, and a large forward voltage Vf is required for device driving of the device. On the other hand, it can be considered that the larger the forward voltage Vf applied for device driving, the more easily electrons with a high carrier concentration and a long diffusion length overflow in the p-type electron blocking layer. At this time, the light emission output of the DUV-LED decreases corresponding to the amount of deterioration in the electron injection efficiency. However, it can be considered that if the Al composition of the barrier layer is increased, the effect of suppressing electron overflow can be obtained, and thus the light emission output will increase. Among 200 to 350 nm that require a large forward voltage Vf, if the center wavelength of the light is 300 nm or less, the effect of the present invention brought about by increasing the Al composition of the barrier layer is particularly large. On the other hand, in the wavelength region where the center wavelength exceeds 300 nm, compared with the wavelength region where the center wavelength is 300 nm or less, the Al composition of the electron blocking layer can be set lower, and it is easy to obtain the effect of improving the hole injection efficiency in the electron blocking layer. Even in this case, the anti-overflow effect brought about by increasing the Al composition of the barrier layer by 40w is also effective, and although it is smaller than that in the wavelength region of 300 nm or less, it has the effect of the present invention. It can also be considered that this is because if the Al composition of the barrier layer is increased, the electron concentration flowing into the well layer close to the p-type electron blocking layer decreases. It should be noted that although it is considered that the overflow may be reduced by increasing the Al composition of the p-type electron blocking layer, the result in this case is a reduction in hole injection, and it is speculated that an adverse effect may occur when the center wavelength of the light is 300 nm or less.

[0060] <AlN guiding layer>

[0061] The AlN guiding layer 50 is disposed adjacent to and on the light-emitting layer 40. The AlN guiding layer 50 is most preferably a nitride semiconductor layer composed of AlN formed by setting the composition ratio of Al of group III elements to 100%. However, considering the inevitable mixing of other group III elements (such as Ga) during the manufacturing process, the gases generated during modification, or the modification intensification situation, as a result, if the Al composition ratio is 96% to 100%, it is included in the AlN guiding layer 50. The thickness of the AlN guiding layer 50 is preferably 0.5 nm or more and 2.0 nm or less, more preferably 0.7 nm or more and 1.7 nm or less. The AlN guiding layer 50 is preferably undoped (i-type), and p-type dopants such as Mg or n-type dopants such as Si may also be added. In addition, the impurity concentration in the AlN guiding layer 50 does not need to be uniform. For example, the impurity concentration may be different between the light-emitting layer 40 side and the p-type layer 70 side. When dopants are added, not only the i-type, as a result, p-type or n-type conversion may occur partially or entirely.

[0062] It should be noted that "i-type" means: as described above, a layer that does not actively add specific impurities (also called an undoped layer). In addition, even if more p-type dopants diffuse compared to the p-type layer 70, specific impurities are not actively added.

[0063] <Final barrier layer>

[0064] Here, the group III nitride semiconductor light-emitting element 100 may further have a final barrier layer between the Nth well layer 40w on the AlN guiding layer 50 side in the light-emitting layer 40 and the AlN guiding layer 50, with a bandgap greater than or equal to that of the barrier layer 40b and less than that of the AlN guiding layer 50. When using Al f Ga 1-f N material as the final barrier layer, the Al composition ratio (f) of the final barrier layer is preferably b ≤ f ≤ 0.95 relative to the Al composition ratio (b) of the barrier layer. At this time, the thickness of the final barrier layer is set to 1.5 nm or less, more preferably 0.1 nm or more and 1.0 nm or less, which is very thin compared to the thickness of the final barrier layer used in the prior art. When a part of the final barrier layer becomes the AlN guiding layer through modification during the change of the carrier gas described in the aforementioned Patent Document 2, if the thickness of the final barrier layer is 0.1 nm or more, one atomic layer that is not affected by the modification remains, so that the modification of the well layer 40w on the Nth layer (the electron blocking layer 60 side) can be avoided.

[0065] <Electron blocking layer>

[0066] Next, the electron blocking layer 60 is disposed adjacent to the AlN guiding layer 50. Generally, the electron blocking layer 60 functions as a layer for blocking electrons, injecting electrons into the light-emitting layer (the well layer in the case of MQW), and improving the electron injection efficiency by being disposed between the quantum well structure (MQW) that functions as the light-emitting layer and the p-type layer (p-type cladding layer or p-type contact layer). This is because when the Al composition ratio of the light-emitting layer is high, the hole concentration in the p-type layer 70 is low, so it is difficult to inject holes into the light-emitting layer, and a part of the electrons flow to the p-type layer 70 side. As a result, by providing the electron blocking layer 60, this electron flow can be prevented. In the present embodiment, the electron blocking layer 60 disposed adjacent to the AlN guiding layer 50 can prevent the flow of electrons to the p-type layer 70 side in the same manner as the above-described layer, and can improve the electron injection efficiency.

[0067] However, as described above, in the past, for such an electron blocking layer 60, compared with the Al composition ratio (b) of the barrier layer 40b, for example, Al z Ga 1-z N material (b < z < 1), the Al composition ratio (z) is usually set higher than the Al composition ratio (b) of the barrier layer. However, in the present invention, contrary to this common technical knowledge, the Al composition ratio (z) of the electron blocking layer is made smaller than the Al composition ratio (b) of the barrier layer. And the present inventors have found that by setting the electron blocking layer 60 to Al z Ga 1-z N (0.5 ≤ z ≤ 0.8), and having an Al composition ratio (z) smaller than the Al composition ratio (b) of the barrier layer 40b, and setting z + 0.01 ≤ b (i.e., z ≤ b - 0.01), a further improvement in light output can be obtained. The overall thickness of the electron blocking layer 60 is preferably, for example, 6 nm to 60 nm. It should be noted that for the p-type dopant doped in the electron blocking layer, the same as the p-type dopant in the p-type layer 70 described later, dopants other than p-type can be doped as needed, or an undoped region can be locally provided.

[0068] <p-type layer>

[0069] The p-type layer 70 disposed adjacent to the electron blocking layer 60 is not particularly limited as long as it can inject holes into the light-emitting layer 40, and can be of a conventional configuration, or a multi-layer structure made of an AlGaN material with a different Al composition ratio and including only a p-type contact layer or a p-type contact layer above the p-type cladding layer (details will be described later). In addition, examples of the p-type dopant doped in the p-type layer 70 include Mg, Zn, Ca, Be, Mn, etc. In addition, the overall average doping concentration of the p-type layer 70 is not particularly limited as long as it is a doping concentration that can function as a p-type, and can be set to, for example, 1.0×10 18 atoms / cm3 ~5.0×10 21 atoms / cm 3 。

[0070] The Al composition ratio of the p-type "cladding" means: a composition ratio that is more than 0.1 less than the Al composition ratio of the electron blocking layer and more than 0.1 greater than the p-type contact layer. When the Al composition ratio of the p-type cladding is set as y, the Al composition ratio of the electron blocking layer 60 is set as z, and the Al composition ratio of the p-type contact layer is set as x, x + 0.1 < y < z - 0.1.

[0071] It should be noted that in the group-III nitride semiconductor light-emitting element 100 based on this embodiment, the p-type cladding is optional and can be not provided. Preferably, the p-type layer 70 is composed only of the p-type contact layer. It should be noted that if the p-type cladding is provided, its thickness can be set to 2 nm to 300 nm. In addition, the thickness of the p-type contact layer can be set to 5 nm or more and 200 nm or less. It should be noted that although not shown, the p-type contact layer is also preferably a multi-layer structure (including a superlattice structure) in which any one or more of the Al composition ratio, dopant type, doping concentration, carrier gas type during formation, etc. are changed.

[0072] -Specific Manner-

[0073] Hereinafter, for Figure 2 the illustrated substrate 10, AlN layer 20, n-type electrode 80, and p-type electrode 90, their specific manners will be illustratively described, but they can be variously deformed. As described above, in the embodiment based on the present invention, Figure 2 the illustrated substrate 10, AlN layer 20, n-type electrode 80, and p-type electrode 90 are not limited to the present invention at all.

[0074] As the substrate 10 of the group-III nitride semiconductor light-emitting element 100, a sapphire substrate can be used. An AlN template substrate provided with an AlN layer epitaxially grown on the surface of the sapphire substrate can also be used. As the sapphire substrate, any sapphire substrate can be used, and the presence or absence of a tilt angle is arbitrary. When a tilt angle is provided, the crystal axis orientation of the tilt direction can be either the m-axis direction or the a-axis direction. For example, the main surface of the sapphire substrate can be set as a surface that is tilted at a tilt angle θ of 0.5 degrees with respect to the C plane. When using the AlN template substrate, it is preferable that the crystallinity of the AlN layer on the surface of the sapphire substrate is excellent. In addition, it is also preferable that an undoped AlGaN layer is provided on the surface of the AlN template substrate. In addition, as the substrate 10, an AlN single crystal substrate can also be used.

[0075] The n-type electrode 80 can be, for example, a metal composite film having a Ti-containing film and an Al-containing film formed on the Ti-containing film, and its thickness, shape, and size can be appropriately selected according to the shape and size of the light-emitting element.

[0076] In addition, for the p-type electrode 90, it can also be made into, for example, a metal composite film having a Ni-containing film and an Au-containing film formed on the Ni-containing film, and its thickness, shape, and size can be appropriately selected according to the shape and size of the light-emitting element.

[0077] (Manufacturing method of group-III nitride semiconductor light-emitting element: First embodiment)

[0078] Next, a first embodiment of the manufacturing method of the group-III nitride semiconductor light-emitting element 100 based on the present invention will be described. The manufacturing method of the first embodiment includes the following steps: First step, forming an n-type group-III nitride semiconductor layer 30 (hereinafter denoted as n-type layer 30); Second step, forming a group-III nitride semiconductor light-emitting layer 40 (hereinafter denoted as light-emitting layer 40) on the n-type layer 30 by alternately laminating N layers of a barrier layer 40b and a well layer 40w having a bandgap smaller than that of the barrier layer 40b in sequence (where N is an integer); Third step, forming an AlN guiding layer 50 on the light-emitting layer 40; Fourth step, forming an electron blocking layer 60 on the AlN guiding layer 50; and Fifth step, forming a p-type group-III nitride semiconductor layer 70 on the electron blocking layer 60. And regarding setting the electron blocking layer 60 as p-type Al z Ga 1-z N (0.50 ≤ z ≤ 0.80), and setting the barrier layer 40b as n-type Al b Ga 1-b N (z + 0.01 ≤ b ≤ 0.95), as described above, is a characteristic matter unique to the present invention.

[0079] Here, in the first embodiment, in the above third step, a raw material gas containing trimethylaluminum gas and ammonia gas can be used to epitaxially grow the AlN guiding layer 50.

[0080] First, as the substrate 10, a sapphire substrate is usually prepared. It is preferable to form an AlN template substrate having an AlN layer 20 formed on the surface of the substrate 10, and a commercially available AlN template substrate can also be used. It should be noted that the AlN layer 20 can be formed by a known thin film growth method such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or sputtering.

[0081] Trimethylaluminum (TMA) can be used as the Al source for the AlN layer 20. Additionally, ammonia (NH3) gas can be used as the N source. These source gases can be used to form the AlN layer 20 by using hydrogen as the carrier gas.

[0082] It should be noted that the growth temperature of the AlN layer 20 is not particularly limited, preferably 1270 °C or higher and 1350 °C or lower, more preferably 1290 °C or higher and 1330 °C or lower. If within this temperature range, the crystallinity of the AlN layer 20 can be improved during subsequent heat treatment processes. Additionally, the growth pressure in the chamber can be set, for example, to 5 Torr to 20 Torr. More preferably, it is 8 Torr to 15 Torr.

[0083] Furthermore, for the molar ratio of group V elements to group III elements (hereinafter referred to as the V / III ratio) calculated based on the growth gas flow rates of group V element gases such as NH3 gas and group III element gases such as TMA gas, it can be set, for example, to 130 or higher and 190 or lower. More preferably, it is 140 or higher and 180 or lower. It should be noted that there is an optimal V / III ratio depending on the growth temperature and growth pressure. Therefore, it is preferable to appropriately set the growth gas flow rates.

[0084] Next, it is preferable that: for the AlN layer 20 on the substrate 10 formed of sapphire obtained as described above, heat treatment is performed at a temperature higher than the growth temperature of the AlN layer 20. This heat treatment process can be carried out using a known heat treatment furnace. By performing this heat treatment, the full width at half maximum of the X-ray rocking curve of the (10 - 12) plane of the AlN layer 20 can be made 400 seconds or less, enabling high crystallinity.

[0085] Thereafter, it is also preferable to form an undoped AlGaN layer on the AlN layer 20. By using TMA as the Al source, trimethylgallium (TMG) as the Ga source, and NH3 gas as the N source, a layer composed of AlGaN material can be formed, which is the same in the formation of the n-type layer 30, n-type guiding layer 35, light-emitting layer 40, final barrier layer, AlN guiding layer 50, electron blocking layer 60, and p-type layer 70 described below. These source gases are supplied into the chamber using hydrogen or nitrogen or a mixed gas of both as the carrier gas. Additionally, for the V / III ratio calculated based on the growth gas flow rates of group V element gases such as NH3 gas and group III element gases such as TMA gas, it can be set, for example, to 100 or higher and 100000 or lower. More preferably, it is 300 or higher and 30000 or lower. Since there is an optimal V / III ratio depending on the growth temperature and growth pressure, it is preferable to appropriately set the growth gas flow rates in the same manner as in the case of forming the AlN layer 20.

[0086] Next, a first process of forming the n-type layer 30 is performed. The n-type layer 30 can be formed on the AlN layer 20, preferably on an undoped AlGaN layer. Regarding the n-type dopant, as described above.

[0087] Next, a second process of forming the light-emitting layer 40 is performed. When adjusting the Al composition ratio in forming the well layer 40w and the barrier layer 40b, it is sufficient to appropriately change the ratio of the flow rate of the Al source to the flow rate of the Ga source. When forming the light-emitting layer 40 with an AlGaN material, it is preferable to set the growth temperature to 1000 °C or higher and 1400 °C or lower, and more preferably to 1050 °C or higher and 1350 °C or lower.

[0088] Next, a third process of forming the AlN guiding layer 50 on the light-emitting layer 40 is performed. In the first embodiment, in this process, a raw material gas containing trimethylaluminum gas (TMA gas) and ammonia gas (NH3 gas) is used to epitaxially grow the AlN guiding layer 50 directly on the light-emitting layer 40. In order to actively exclude the incorporation of other group III elements such as Ga, it is particularly preferable that the raw material gas consists only of trimethylaluminum gas (TMA gas) and ammonia gas (NH3 gas). As the carrier gas, a carrier gas mainly composed of nitrogen is preferably used, and nitrogen is more preferably used. In addition, it is preferable to set the growth temperature to 1000 °C or higher and 1400 °C or lower, and more preferably to 1050 °C or higher and 1350 °C or lower. By appropriately selecting the growth time, the thickness of the AlN guiding layer 50 can be set to 0.5 nm or more and 2.0 nm or less.

[0089] Next, a fourth process of forming the electron blocking layer 60 on the AlN guiding layer 50 is performed. Further, a fifth process of forming the p-type layer 70 on the electron blocking layer 60 is performed. As described above, the p-type layer 70 can be a single p-type contact layer or a multilayer structure including a p-type cladding layer and a p-type contact layer.

[0090] As the dopant for forming the p-type layer 70, it can be appropriately selected and used from, for example, Mg or Zn, etc. As the Mg source, cyclopentadienylmagnesium (CP2Mg) can be used, and as the Zn source, ZnCl2 can be used. When doping a mixture of multiple dopants, it is sufficient to supply a mixed gas of the dopant sources to the chamber.

[0091] Here, with Al z Ga 1-zWhen forming the electron blocking layer 60 with N material, a gas with hydrogen as the main component can be used as the carrier gas for forming the electron blocking layer 60. As described above, the source gases are TMA, TMG, and NH3 gases. Furthermore, the gas of the dopant source is appropriately selected and used. It should be noted that when using nitrogen as the carrier gas to form the AlN guiding layer 50 and using hydrogen as the carrier gas to form the electron blocking layer 60, the carrier gas needs to be switched. At this time, after forming the AlN guiding layer 50, the supply of TMA gas is interrupted, the carrier gas is switched from nitrogen to hydrogen, and after about 20 seconds to 1 minute, TMA gas and TMG gas are supplied to form the electron blocking layer 60.

[0092] It should be noted that in this specification, the "carrier gas with hydrogen as the main component" means that the volume ratio of hydrogen to the total volume of the carrier gas is 60% or more. More preferably, it is 85% or more. It should be noted that as long as a gas with the purity commercially available for semiconductor manufacturing use is used. The same meaning applies to the "carrier gas with nitrogen as the main component". It should be noted that the volume ratio of the carrier gas here is targeted at the gas supplied into the chamber and flowing in the space near the wafer, and does not include the gas that is exhausted without flowing in the space near the wafer for the main purpose of purging the heater and the inner wall of the chamber. In other words, even if a large flow of hydrogen is circulated to the heater and the inner wall of the chamber and exhausted, and substantially nitrogen flows near the wafer, it becomes the "carrier gas with nitrogen as the main component".

[0093] In addition, as the growth temperature of the p-type layer 70, it also varies depending on the Al composition ratio, and is preferably 1000 °C or higher and 1400 °C or lower, more preferably 1050 °C or higher and 1350 °C or lower. In addition, for the growth pressure in the chamber, it can be set to, for example, 10 Torr to 760 Torr. More preferably, it is 20 Torr to 380 Torr. Among them, as the growth temperature when forming the p-type contact layer with a small Al composition ratio in the p-type layer 70, it is preferably 800 °C or higher and 1400 °C or lower, more preferably 900 °C or higher and 1300 °C or lower. In addition, for the growth pressure in the chamber, it can be set to, for example, 10 Torr to 760 Torr, more preferably 20 Torr to 600 Torr. As the carrier gas, as described above, hydrogen or nitrogen or a mixed gas of both can be used. Although not shown, when making the p-type contact layer in the p-type layer into a multi-layer structure in which any one or more of the elements such as the Al composition ratio, the dopant type, the doping concentration, and the type of the carrier gas during formation are changed, the carrier gas on the AlN guiding layer 50 side can be set to hydrogen, and the opposite side (i.e., the p-type electrode 90 side) can be set to nitrogen, or vice versa. A p-type cladding can be provided, but as described above, it is preferably not provided.

[0094] Finally, a part of the light-emitting layer 40, the AlN guiding layer 50, the electron blocking layer 60, and the p-type layer 70 can be removed by etching or the like, and an n-type electrode 80 is formed on the exposed n-type layer 30, and a p-type electrode 90 is formed on the p-type layer 70, respectively. By performing such operations, the group-III nitride semiconductor light-emitting element 100 can be fabricated according to the manufacturing method of the first embodiment of the present invention.

[0095] (Manufacturing Method of Group-III Nitride Semiconductor Light-Emitting Element: Second Embodiment)

[0096] In the second embodiment, instead of directly forming the AlN guiding layer 50 on the light-emitting layer 40, an AlGaN layer having an Al composition ratio greater than or equal to that of the barrier layer 40b and less than that of the AlN guiding layer 50 is formed on the light-emitting layer 40 in the third process, and the AlN guiding layer 50 is formed by modifying the aforementioned AlGaN layer. Except for this, it is the same as the first embodiment. When the carrier gas is switched from nitrogen to hydrogen before forming the electron blocking layer 60, the AlGaN layer formed by the third process is exposed in a carrier gas atmosphere (for example, a carrier gas atmosphere mainly composed of hydrogen) having a lower nitrogen partial pressure than during growth, and thus modification occurs in which Ga is removed from the surface. As a result, the surface side is converted from the AlGaN layer to the AlN guiding layer 50, and the light-emitting layer side remains as the final barrier layer. According to the thickness of the AlGaN layer and the exposure time in a carrier gas atmosphere having a lower nitrogen partial pressure than during growth after stopping the supply of the group-III element source gas, the thicknesses of the aforementioned AlN guiding layer 50 and the final barrier layer can be controlled.

[0097] Examples

[0098] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the following examples at all.

[0099] [Example 11]

[0100] Prepare a sapphire substrate (diameter: 2 inches, thickness: 430 μm, plane orientation: (0001), m-axis direction deviation angle θ: 0.5 degrees). Next, grow an AlN layer with a center film thickness of 0.60 μm (average film thickness of 0.61 μm) on the above sapphire substrate by MOCVD method to fabricate an AlN template substrate. At this time, the growth temperature of the AlN layer is 1300 °C, the growth pressure in the chamber is 10 Torr, and the growth gas flow rates of ammonia gas and TMA gas are set so that the V / III ratio reaches 163. The flow rate of group V element gas (NH3) is 200 sccm, and the flow rate of group III element gas (TMA) is 53 sccm. It should be noted that for the film thickness of the AlN layer, a light interference type film thickness measuring machine (Nanospec M6100A; manufactured by NANOMETRICS) is used to measure the film thickness at a total of 25 sites equally spaced and dispersed including the center in the crystal plane.

[0101] Next, introduce the above AlN template substrate into a heat treatment furnace, evacuate to 10 Pa and then purge with nitrogen to normal pressure, thereby making the inside of the furnace a nitrogen atmosphere, and then raise the temperature inside the furnace to perform heat treatment on the AlN template substrate. At this time, the heating temperature is set to 1650 °C and the heating time is set to 4 hours.

[0102] Next, by MOCVD method, as an undoped AlGaN layer, form an undoped AlGaN layer with an Al composition ratio of 0.85 to 0.65 and a composition gradient along the crystal growth direction and a thickness of 200 nm. Next, as an n-type layer, form an n-type layer with a thickness of 2 μm composed of Al 0.65 Ga 0.35 N and doped with Si. It should be noted that as a result of SIMS analysis, the Si concentration in the n-type layer is 1.0×10 19 atoms / cm 3 .

[0103] Next, form an n-type guiding layer with a thickness of 20 nm composed of Al 0.65 Ga 0.35 N and doped with Si on the n-type layer. Furthermore, form an Al 0.70 Ga 0.30 N with a thickness of 4 nm as a barrier layer. Next, alternately form two layers each of a well layer with a thickness of 3 nm composed of Al 0.45 Ga 0.55 N and a barrier layer with a thickness of 4 nm composed of Al 0.70 Ga 0.30 N, and then form an Al 0.45 Ga 0.55A well layer with a thickness of 3 nm composed of N. That is, both the number of well layers and the number of barrier layers N are 3, the Al composition ratio (b) of the barrier layer is 0.70, and the Al composition ratio (w) of the well layer is 0.45. It should be noted that Si is doped during the formation of the barrier layer.

[0104] Thereafter, on the third well layer, using nitrogen as the carrier gas, an undoped AlN guiding layer is formed. The thickness of the AlN guiding layer is set to 1 nm. Then, the supply of TMA gas is stopped, and ammonia gas is continuously supplied. In this state, the nitrogen of the carrier gas is stopped and hydrogen is supplied to change the carrier gas to hydrogen, and then the TMA gas and TMG gas as group III element source gases are supplied again to form a layer difference of 40 nm electron blocking layer composed of Al 0.68 Ga 0.32 N and doped with Mg. That is, the Al composition ratio (z) of the electron blocking layer is 0.68, the Al composition ratio (b) of the barrier layer is greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) is 0.02.

[0105] Next, after switching the carrier gas to nitrogen, a p-type layer (p-type contact layer) with a thickness of 150 nm composed of GaN and doped with Mg is formed. It should be noted that in the region with a thickness of 25 nm in contact with the electrode within the 150 nm thickness, the flow rate of TMG gas is reduced and the probability of Mg presence is increased, and the growth rate is reduced, thereby forming a layer with a high Mg concentration. As a result of SIMS analysis, the average Mg concentration of the p-type layer in the 125 nm part on the p-type electron blocking layer side is 3.0×10 19 atoms / cm 3 , and the average Mg concentration of the part with a high Mg concentration is 1.2×10 20 atom / cm 3 .

[0106] Thereafter, a mask is formed on the p-type layer and mesa etching is performed by dry etching to expose a part of the n-type layer. Next, a p-type electrode composed of Ni / Au is formed on the p-type layer, and an n-type electrode composed of Ti / Al is formed on the exposed n-type layer. It should be noted that among the p-type electrodes, the thickness of Ni is the thickness of Au is In addition, among the n-type electrodes, the thickness of Ti is the thickness of Al is Finally, contact annealing (RTA) is performed at 550 °C to form the electrodes.

[0107] The compositions of the respective layers of the group III nitride semiconductor light-emitting element fabricated as described above are shown in Table 1.

[0108] [Table 1]

[0109]

[0110] [Example 12]

[0111] Set the Al composition ratio (b) of the barrier layer to 0.71 and the Al composition ratio of the n-type guiding layer to 0.71. Except for this, perform the same operations as in Example 11 to fabricate a Group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer is 0.68, the Al composition ratio (b) of the barrier layer is greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) is 0.03.

[0112] [Example 13]

[0113] Set the Al composition ratio b of the barrier layer to 0.75. Except for this, perform the same operations as in Example 11 to fabricate a Group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer is 0.68, the Al composition ratio (b) of the barrier layer is greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) is 0.07.

[0114] [Example 14]

[0115] Set the Al composition ratio (b) of the barrier layer to 0.80. Except for this, perform the same operations as in Example 11 to fabricate a Group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer is 0.68, the Al composition ratio (b) of the barrier layer is greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) is 0.12.

[0116] [Example 15]

[0117] Set the Al composition ratio (b) of the barrier layer to 0.85. Except for this, perform the same operations as in Example 11 to fabricate a Group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer is 0.68, the Al composition ratio (b) of the barrier layer is greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) is 0.17.

[0118] [Comparative Example 11]

[0119] Set the Al composition ratio (b) of the barrier layer to 0.60. Except for this, perform the same operations as in Example 11 to fabricate a Group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer is 0.68, the Al composition ratio (b) of the barrier layer is less than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) is -0.08.

[0120] [Comparative Example 12]

[0121] The Al composition ratio (b) of the barrier layer was set to 0.65, and otherwise, the same operations as in Example 11 were performed to fabricate a group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer was 0.68, the Al composition ratio (b) of the barrier layer was less than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) was -0.03.

[0122] [Comparative Example 13]

[0123] The Al composition ratio (b) of the barrier layer was set to 0.68, and the Al composition ratio of the n-type guiding layer was set to 0.68. Otherwise, the same operations as in Example 11 were performed to fabricate a group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer was 0.68, the Al composition ratio (b) of the barrier layer was the same as the Al composition ratio (z) of the electron blocking layer, and thus, the difference (b - z) was 0.

[0124] In Examples 11 to 15 and Comparative Examples 11 to 13, when the Al composition ratio (z) of the p-type electron blocking layer was set to 0.68, an experiment of changing it to 0.63 was conducted. Hereinafter, the fabrication conditions of the group-III nitride semiconductor light-emitting elements of Examples 21 to 23 and Comparative Example 21 will be described.

[0125] [Example 21]

[0126] The Al composition ratio (b) of the barrier layer was set to 0.65, and the Al composition ratio (z) of the electron blocking layer was set to 0.63. Otherwise, the same operations as in Example 11 were performed to fabricate a group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer was 0.63, the Al composition ratio (b) of the barrier layer was greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) was 0.02.

[0127] [Example 22]

[0128] The Al composition ratio (b) of the barrier layer was set to 0.75, and the Al composition ratio (z) of the electron blocking layer was set to 0.63. Otherwise, the same operations as in Example 11 were performed to fabricate a group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer was 0.63, the Al composition ratio (b) of the barrier layer was greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) was 0.12.

[0129] [Example 23]

[0130] The Al composition ratio (b) of the barrier layer was set to 0.80, and the Al composition ratio (z) of the electron blocking layer was set to 0.63. Except for this, the same operations as in Example 11 were performed to fabricate a group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer was 0.80, the Al composition ratio (b) of the barrier layer was greater than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) was 0.17.

[0131] [Comparative Example 21]

[0132] The Al composition ratio (b) of the barrier layer was set to 0.60, and the Al composition ratio (z) of the electron blocking layer was set to 0.63. Except for this, the same operations as in Example 11 were performed to fabricate a group-III nitride semiconductor light-emitting element. The Al composition ratio (z) of the electron blocking layer was 0.63, the Al composition ratio (b) of the barrier layer was less than the Al composition ratio (z) of the electron blocking layer, and the difference (b - z) was -0.03.

[0133] (Evaluation 1: Evaluation of the thickness and Al composition of each layer)

[0134] For Examples 11 to 15, 21 to 23, Comparative Examples 11 to 13, and 21, the thicknesses of the respective layers formed by epitaxial growth were measured using an optical interference type film thickness measuring device.

[0135] In addition, for layers with thicknesses as thin as several nm to several tens of nm including the barrier layer and the blocking layer, the thickness and Al composition ratio of each layer were measured using TEM-EDS in the cross-sectional observation of each layer based on a transmission electron microscope.

[0136] In addition, for layers with a sufficiently large thickness (for example, 1 μm or more), the Al composition ratio of the target layer was confirmed from the emission wavelength (bandgap energy) based on photoluminescence measurement.

[0137] (Evaluation 2: Light emission output and light emission)

[0138] For Examples 11 to 15, 21 to 23, Comparative Examples 11 to 13, and 21, a Si photodiode (S1227-1010BQ, manufactured by Hamamatsu Photonics) was used to measure the light emission output when the current was 10 mA. Furthermore, a fiber optic spectrometer (USB2000+, manufactured by Ocean Photonics) was also used to measure the light emission wavelength when the current was 10 mA.

[0139] The results of evaluating the group-III nitride semiconductor light-emitting elements of Examples 11 to 15, 21 to 23, Comparative Examples 11 to 13, and 21 were compared with the Al composition ratios of the n-type guiding layer, the barrier layer, and the electron blocking layer, and are shown in Table 2.

[0140] [Table 2]

[0141]

[0142] It can be confirmed from Table 2 that when the Al composition ratio (b) of the barrier layer is greater than the Al composition ratio (z) of the electron blocking layer, the light emission output can be increased.

[0143] It should be noted that in Examples 21 to 23 and Comparative Example 21, the Al composition ratio (z) of the electron blocking layer was set to 0.63. Compared with the case where the Al composition ratio (z) of the electron blocking layer is 0.68 and b - z is the same, although there is a difference in their light emission output, there is an advantage that the forward voltage becomes lower. In applications where reducing the forward voltage is important, sometimes it is also preferable to reduce the Al composition ratio (z). Thus, the Al composition ratio (z) of the electron blocking layer is appropriately set according to the application. However, regardless of the value of z, when the value of b - z reaches the scope of the present invention, a tendency for the light emission output to increase is exhibited.

[0144] Industrial Applicability

[0145] According to the present invention, it is possible to provide a group-III nitride semiconductor light-emitting element having a more excellent light emission output than conventional ones, and thus it is useful.

[0146] Explanation of Reference Numerals

[0147] 10 Substrate

[0148] 20 AlN layer

[0149] 30 n-type layer

[0150] 40 Light-emitting layer

[0151] 40b Barrier layer

[0152] 40w Well layer

[0153] 50 AlN guiding layer

[0154] 60 Electron blocking layer

[0155] 70 p-type layer

[0156] 80 n-type electrode

[0157] 90 p-type electrode

[0158] 100 Group-III nitride semiconductor light-emitting element

Claims

1. A group-III nitride semiconductor light-emitting element, which is a group-III nitride semiconductor light-emitting element having a light-emitting wavelength of 200 to 350 nm, characterized in that it sequentially has an n-type group-III nitride semiconductor layer, a group-III nitride semiconductor light-emitting layer, an AlN guiding layer, an electron blocking layer, and a p-type group-III nitride semiconductor layer, the group-III nitride semiconductor light-emitting layer is formed by alternately stacking N layers of a barrier layer and a well layer having a bandgap smaller than that of the barrier layer, where N is an integer, the well layer of the Nth layer in the group-III nitride semiconductor light-emitting layer is in contact with the AlN guiding layer, The electron blocking layer is p-type Al z Ga 1-z N, where 0.50 ≤ z ≤ 0.80 The barrier layer is n-type Al b Ga 1-b N, where z + 0.01 ≤ b ≤ 0.

95.

2. The group-III nitride semiconductor light-emitting device according to claim 1, wherein, the Al composition ratio (b) of the barrier layer is b ≤ z + 0.

20.

3. The group-III nitride semiconductor light-emitting element according to claim 1 or 2, wherein, The thickness of the AlN guiding layer is 0.5 nm or more and 2.0 nm or less.

4. A group-III nitride semiconductor light-emitting element, which is a group-III nitride semiconductor light-emitting element having a light-emitting wavelength of 200 to 350 nm, characterized in that it sequentially has an n-type group-III nitride semiconductor layer, a group-III nitride semiconductor light-emitting layer, a final barrier layer, an AlN guiding layer, an electron blocking layer, and a p-type group-III nitride semiconductor layer, the group-III nitride semiconductor light-emitting layer is formed by alternately stacking N layers of a barrier layer and a well layer having a bandgap smaller than that of the barrier layer, where N is an integer, the final barrier layer is between the well layer of the Nth layer in the group-III nitride semiconductor light-emitting layer and the AlN guiding layer, the Al composition ratio of the final barrier layer is greater than or equal to that of the barrier layer and less than that of the AlN guiding layer, and the thickness of the final barrier layer is 1.5 nm or less The electron blocking layer is p-type Al z Ga 1-z N, where 0.50 ≤ z ≤ 0.80, The barrier layer is n-type Al b Ga 1-b N, where z + 0.01 ≤ b ≤ 0.

95.

5. The group-III nitride semiconductor light-emitting element according to claim 4, wherein, the Al composition ratio (b) of the barrier layer is b ≤ z + 0.

20.

6. The group-III nitride semiconductor light-emitting element according to claim 4 or 5, wherein, The thickness of the AlN guiding layer is 0.5 nm or more and 2.0 nm or less.

7. A method for manufacturing a group-III nitride semiconductor light-emitting element, characterized in that, It is a method for manufacturing a group-III nitride semiconductor light-emitting element having a light-emitting wavelength of 200 to 350 nm, including the following steps: The first step, forming an n-type group-III nitride semiconductor layer; The second step, alternately stacking N layers of a barrier layer and a well layer having a bandgap smaller than that of the barrier layer on the n-type group-III nitride semiconductor layer to form a group-III nitride semiconductor light-emitting layer, where N is an integer; The third step, forming an AlN guiding layer on the group-III nitride semiconductor light-emitting layer; The fourth step, forming an electron blocking layer on the AlN guiding layer; and, The fifth step, forming a p-type semiconductor layer on the electron blocking layer, where Set the electron blocking layer to p-type Al z Ga 1-z N, 0.50 ≤ z ≤ 0.80, Set the barrier layer as n-type Al b Ga 1-b N, where z + 0.01 ≤ b ≤ 0.95.

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