JP6993843B2 - Nitride semiconductor light emitting device and method for manufacturing a nitride semiconductor light emitting device - Google Patents

Description

The present invention relates to a nitride semiconductor light emitting device and a method for manufacturing a nitride semiconductor light emitting device.

In recent years, nitride semiconductor light emitting devices such as light emitting diodes and laser diodes that output ultraviolet light have been provided, and development of nitride semiconductor light emitting devices with improved light emission intensity is underway (see Patent Document 1). ..

Japanese Patent No. 4291960

The nitride semiconductor light emitting element described in Patent Document 1 is a nitride semiconductor light emitting element having a structure in which an active layer is sandwiched between a p-type clad layer and an n-type clad layer on a nitride semiconductor substrate. It is a quantum well structure consisting of a barrier layer and a well layer in which the total number of well layers is 2 or less, both between the n-type clad layer and the active layer, and between the p-type clad layer and the active layer. Has a second nitride semiconductor layer composed of Al _c Ga _1-c N (0 ≦ c <1), and nitrides containing In between the active layer and the second nitride semiconductor layer. It has a first nitride semiconductor layer made of a physical semiconductor, and the first nitride semiconductor layer has a multilayer film structure containing In _z Ga _1-z N (0 <z ≦ 1), and the active layer. An electron confinement layer composed of Al _γ Ga _1-γ N (0 <γ <1) is provided between the first nitride semiconductor layer on the p side and the active layer, and the active layer has two or more barrier layers. The barrier layer having and located on the most p-type layer side is formed on the most p-side in the active layer, substantially free of n-type impurities, contains p-type impurities, and the other barrier layers are undoped or n. The p-type clad layer and the n-type clad layer contain type impurities, and are characterized in that the p-type clad layer and the n-type clad layer are composed of an Al _b Ga _1-b N (0.05 <b <1) and a super lattice of GaN.

By the way, in order to improve the flatness of the surface of the nitride semiconductor light emitting device, it is preferable to increase the number of superlattices stacked. However, as the number of superlattices stacked increases, the warpage of the wafer, which is the material of the nitride semiconductor light emitting device, increases, which may hinder the processing of the light emitting device.

Therefore, the present invention provides a nitride semiconductor light emitting device and a method for manufacturing a nitride semiconductor light emitting device, which can suppress the warp of a wafer, which is a material of the nitride semiconductor light emitting device, and make it difficult for the processing of the light emitting device to be hindered. The purpose is to do.

An object of the present invention is to solve the above-mentioned problems, an n-type clad layer formed of an n-type AlGaN located on a base structure including a substrate, and a plurality of barriers located on the n-type clad layer. A nitride semiconductor light emitting device including a multiplex quantum well layer in which layers and a plurality of well layers are alternately laminated in this order, wherein the n-type clad layer is located on the base structure side and is a second device. An Al that is located between the first AlGaN layer formed of n-type AlGaN having an Al composition ratio of 1 and the first AlGaN layer and the multiple quantum well layer, and is equal to or less than the first Al composition ratio. A buffer layer in which a plurality of layers formed of AlGaN having a composition ratio are alternately laminated is provided , and the buffer layer is formed by alternately stacking two types of layers formed of AlGaN having different Al composition ratios. The two types of layers are smaller than the second AlGaN layer containing AlGaN having a second Al composition ratio equal to or lower than the first Al composition ratio and the second Al composition ratio. A nitride semiconductor light emitting device and a nitride semiconductor light emitting device including a third AlGaN layer containing AlGaN having a third Al composition ratio, wherein the third AlGaN layer has a thickness larger than the thickness of the second AlGaN layer. Provided is a method for manufacturing a nitride semiconductor light emitting device.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a nitride semiconductor light emitting device and a method for manufacturing a nitride semiconductor light emitting device, which can suppress the warp of a wafer and make it difficult for the processing of the light emitting device to be hindered.

FIG. 1 is a cross-sectional view schematically showing the configuration of a nitride semiconductor light emitting device according to the first embodiment of the present invention. FIG. 2 is a graph schematically showing an example of the Al composition ratio of the n-type clad layer of the light emitting device shown in FIG. 1. FIG. 3 is a graph schematically showing an example of the Al composition ratio of the n-type clad layer of the light emitting device according to the modified example. FIG. 4 is a diagram showing configurations of light emitting elements according to Comparative Examples and Examples and measurement results. FIG. 5 is a graph showing the warp of the wafer, which is the material of the light emitting element according to the comparative example and the embodiment, and the in-plane light emission ratio of the wafer. FIG. 6 is a graph schematically showing an example of the Al composition ratio of the n-type clad layer of the light emitting device according to the second embodiment of the present invention.

[First Embodiment]
The first embodiment of the present invention will be described with reference to FIGS. 1 and 2. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect. Further, the dimensional ratio of each component in each drawing does not necessarily match the dimensional ratio of the actual nitride semiconductor light emitting device.

FIG. 1 is a cross-sectional view schematically showing the configuration of a nitride semiconductor light emitting device according to the first embodiment of the present invention. The nitride semiconductor light emitting device 1 (hereinafter, also simply referred to as “light emitting device 1”) is a light emitting diode (LED) that emits light having a wavelength in the ultraviolet region. In the present embodiment, in particular, a light emitting device 1 that emits deep ultraviolet light having a center wavelength of 280 nm to 360 nm will be described as an example.

As shown in FIG. 1, the light emitting device 1 includes a substrate 10, a buffer layer 22, an n-type clad layer 30, an active layer 50 including a multiple quantum well layer, an electron block layer 60, and a p-type clad layer 70. The p-type contact layer 80, the n-side electrode 90, and the p-side electrode 92 are included.

The semiconductor constituting the light emitting device 1 is, for example, a binary system represented by Al _x Gay In _{1-xy N} (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). A ternary or quaternary group III nitride semiconductor can be used. Further, a part of these Group III elements may be replaced with boron (B), thallium (Tl) or the like, and a part of N may be replaced with phosphorus (P), arsenic (As), antimony (Sb), etc. It may be replaced with bismuth (Bi) or the like.

The substrate 10 has translucency with respect to the deep ultraviolet light emitted by the light emitting element 1. The substrate 10 is, for example, a sapphire substrate containing sapphire (Al ₂ O ₃ ). As the substrate 10, in addition to the sapphire (Al ₂ O ₃ ) substrate, for example, an aluminum nitride (AlN) substrate or an aluminum nitride gallium (AlGaN) substrate may be used.

The buffer layer 22 is formed on the substrate 10. The buffer layer 22 is configured to include an AlN layer. The substrate 10 and the buffer layer 22 form the base structure portion 2. When the substrate 10 is an AlN substrate or an AlGaN substrate, the buffer layer 22 does not necessarily have to be provided.

The n-type clad layer 30 is formed on the base structure portion 2. The n-type clad layer 30 is a layer formed of n-type AlGaN (hereinafter, also simply referred to as “n-type AlGaN”), and contains, for example, AlGaN doped with silicon (Si) as an n-type impurity. It is a layer. As the n-type impurities, germanium (Ge), selenium (Se), tellurium (Te), carbon (C) and the like may be used.

The n-type clad layer 30 includes a first AlGaN layer 32 formed on the base structure portion 2 and a buffer layer 34 formed on the first AlGaN layer 32. In other words, the n-type clad layer 30 is located between the first AlGaN layer located on the base structure portion 2 side, the first AlGaN layer 32, and the multiple quantum well layer described later in the n-type clad layer 30. It is provided with a cushioning layer 34 located at.

Next, the details of the first AlGaN layer 32 and the buffer layer 34 will be described with reference to FIG. FIG. 2 is a graph schematically showing an example of the Al composition ratio of the n-type clad layer 30 of the light emitting device 1 shown in FIG. As another expression, "AlN mole fraction" (%) may be used for the Al composition ratio. The vertical axis of FIG. 2 shows the Al composition ratio (%) of the n-type clad layer 30, and the horizontal axis schematically shows the positions of the first AlGaN layer 32 and the buffer layer 34 constituting the n-type clad layer 30. Shows. Reference numerals “t ₁ ”, “t ₂ ”, and “t ₃ ” in FIG. 2 are for the first AlGaN layer 32, the second AlGaN layer 342 (described later), and the third AlGaN layer 344 (described later), respectively. Shows the thickness.

As shown in FIG. 2, the first AlGaN layer 32 is a layer formed in Al _q Ga _1-q N (0 <q ≦ 1) having the first Al composition ratio q. Further, the first AlGaN layer 32 has a thickness t ₁ of 1.5 μm (micrometer) or less.

The buffer layer 34 is a layer in which a plurality of layers formed of AlGaN having an Al composition ratio equal to or lower than the first Al composition ratio are alternately formed. Specifically, the buffer layer 34 includes a multi-layer in which two types of layers 342 and 344 respectively formed of AlGaN having different Al composition ratios equal to or lower than the first Al composition ratio are alternately laminated. There is. More specifically, the buffer layer 34 includes a multi-layer in which two types of layers 342 and 344 are alternately laminated with L (L is a natural number) layers.

More specifically, the buffer layer 34 has an Al _u Ga _1-u having a relatively large Al composition ratio (hereinafter, “second Al composition ratio u”) among the two types of layers 342 and 344. Al _v Ga _1-v having a second AlGaN layer 342 formed by N (0 <u ≦ q ≦ 1) and a relatively small Al composition ratio (hereinafter, “third Al composition ratio v”). It includes a third AlGaN layer 344 formed by N (0 <v <u ≦ q ≦ 1).

In other words, the buffer layer 34 has a second AlGaN layer 342 containing AlGaN having a second Al composition ratio u equal to or less than the first Al composition ratio, and a third Al smaller than the second Al composition ratio. It includes a third AlGaN layer 344 containing AlGaN having a composition ratio v.

The second AlGaN layer 342 is formed on the first AlGaN layer 32. Further, the second AlGaN 342 and the third AlGaN layer 344 are alternately laminated with each other in this order from the first AlGaN layer 32 toward the multiple quantum well layer described later. L can be appropriately selected, for example, 15, 20, 30, and the like.

Preferably, the thickness of the buffer layer 34 ((t ₂ + t ₃ ) xL) is 4.0 μm or less. Also, preferably, the thickness t ₃ of the third AlGaN layer 344 is larger than the thickness t ₂ of the second AlGaN layer 342. That is, t ₂ and t ₃ have a relationship of t ₂ <t ₃ . Each of the second AlGaN layer 342 and the third AlGaN layer 344 has a thickness as small as 4.0 μm or less (for example, several tens of nm) even if it is thick. The second AlGaN layer 342 and the third AlGaN layer 344 may be superlattice layers.

The active layer 50 including the multiple quantum well layer is formed on the n-type clad layer 30. The active layer 50 is a three-layered layer including a barrier layer 52a on the n-type clad layer 30 side of a multiple quantum well layer composed of Allr Ga _{1-r N} and a barrier layer 52c on the electron block layer 60 side described later. With the three well layers 54a, 54b, 54c (0 ≦ r ≦ 1, 0 ≦ s ≦ 1, r> s) including the barrier layers 52a, 52b, 52c and Al _s Ga _1-s N. It is a layer including a multiple quantum well layer in which is alternately laminated. The active layer 50 is configured to have a band gap of 3.4 eV or more in order to output deep ultraviolet light having a wavelength of 360 nm or less. In the present embodiment, the active layer 50 is provided with three barrier layers 52a, 52b, 52c and three well layers 54a, 54b, 54c, but the active layer 50 is not necessarily limited to three layers, and two or less layers are provided. However, it may have four or more layers.

The electron block layer 60 is formed on the active layer 50. The electron block layer 60 is formed of p-type AlGaN (hereinafter, also simply referred to as “p-type AlGaN”). The electron block layer 60 has a thickness of about 1 nm to 10 nm. The electron block layer 60 may include a layer formed of AlN. Further, the electron block layer 60 is not necessarily limited to the p-type semiconductor layer, and may be an undoped semiconductor layer.

The p-type clad layer 70 is formed on the electron block layer 60. The p-type clad layer 70 is a layer formed of p-type AlGaN, and is, for example, an AlGaN layer doped with magnesium (Mg) as a p-type impurity. As the p-type impurities, zinc (Zn), beryllium (Be), calcium (Ca), strontium (Sr), barium (Ba) and the like may be used. The p-type clad layer 70 has a thickness of about 300 nm to 700 nm, and has a thickness of, for example, about 400 nm to 600 nm.

The p-type contact layer 80 is formed on the p-type clad layer 70. The p-type contact layer 80 is, for example, a p-type GaN layer doped with impurities such as Mg at a high concentration.

The n-side electrode 90 is formed on a partial region of the n-type clad layer 30. The n-side electrode 90 is formed of, for example, a multilayer film in which titanium (Ti) / aluminum (Al) / Ti / gold (Au) are sequentially laminated on the n-type clad layer 30.

The p-side electrode 92 is formed on the p-type contact layer 80. The p-side electrode 92 is formed of, for example, a nickel (Ni) / gold (Au) multilayer film that is sequentially laminated on the p-type contact layer 80.

(Production method)
Next, a method of manufacturing the light emitting element 1 will be described. A wafer in which a buffer layer 22, an n-type clad layer 30, an active layer 50, an electron block layer 60, and a p-type clad layer 70 are continuously grown at a high temperature on a substrate 10 in this order, for example, while gradually lowering the temperature. To form. As an example, the wafer has a circular shape having a diameter of about 50 mm. The growth of these layers includes the Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), Halide Vapor Phase Epitaxy (NVPE), etc. It can be formed by using the well-known epitaxial growth method of.

Next, a mask is formed on the p-type clad layer 70, and the active layer 50, the electron block layer 60, and the p-type clad layer 70 in the exposed region where the mask is not formed are removed. The active layer 50, the electron block layer 60, and the p-type clad layer 70 can be removed by, for example, plasma etching. The n-side electrode 90 is formed on the exposed surface 30a (see FIG. 1) of the n-type clad layer 30, and the p-side electrode 92 is formed on the p-type contact layer 80 from which the mask has been removed. The n-side electrode 90 and the p-side electrode 92 can be formed by a well-known method such as an electron beam vapor deposition method or a sputtering method. By cutting this wafer into predetermined dimensions, the light emitting element 1 shown in FIG. 1 is formed.

(Example)
Next, an example according to the first embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram showing the configuration of the light emitting element 1 according to the comparative example and the embodiment and the measurement result. FIG. 5 is a graph showing the warp of the wafer, which is the material of the light emitting element according to the comparative example and the embodiment, and the in-plane light emission ratio of the wafer. The “number of loops” in FIG. 4 indicates the number L of each layer of the second AlGaN layer 342 and the third AlGaN layer 344 (also referred to as “stacking number L”).

As shown in FIG. 4, the light emitting device 1 of the embodiment has a buffer layer 34 in which a plurality of second AlGaN layer 342 and a third AlGaN layer 344 are alternately laminated, whereas the light emitting element 1 of the comparative example has a buffer layer 34. The light emitting element is different from each other in that it does not have such a buffer layer 34.

Specifically, as shown in FIG. 4, the light emitting element 1 according to the first embodiment has a first AlGaN layer 32 formed of AlGaN having an Al composition ratio of 39.3% as the first Al composition ratio q. , The second AlGaN layer 344 formed of AlGaN having an Al composition ratio of 39.3% equal to the first Al composition ratio q as the second Al composition ratio u, and the second Al composition ratio v as the third Al composition ratio v. Includes a third AlGaN layer 344 formed of AlGaN having an Al composition ratio of 25.8%, which is smaller than the Al composition ratio u of.

The light emitting element 1 according to the first embodiment includes a multi-layer in which 20 layers of a second AlGaN layer 342 and a third AlGaN layer 344 are alternately laminated. Further, the thickness t ₁ of the first AlGaN layer 32 is 0.2 μm, the thickness t ₂ of the second AlGaN layer 342 is 0.035 μm, and the thickness t of the third AlGaN layer 344 is t. ₃ is 0.085 μm. That is, the thickness of the buffer layer 34 is approximately 2.4 μm ((0.035 + 0.085) x 20).

Further, the light emitting element 1 according to the second embodiment includes first to third AlGaN layers 32, 342 and 344 having the same Al composition ratio as the light emitting element 1 according to the first embodiment described above. The number of layers L of the buffer layer 34 of the light emitting element 1 according to the second embodiment is 15. Further, the thickness t ₁ of the first AlGaN layer 32 is 0.4 μm, the thickness t ₂ of the second AlGaN layer 342 is 0.035 μm, and the thickness t of the third AlGaN layer 344 is t. ₃ is 0.11 μm. That is, the thickness of the buffer layer 34 is approximately 2.18 μm ((0.035 + 0.11) × 15).

With respect to Examples 1 and 2 above, the light emitting device according to the comparative example does not include a layer corresponding to the first AlGaN layer 32. The number of layers is 1. The thickness t ₂ of the second AlGaN layer 342 is 1 μm, and the thickness t ₃ of the third AlGaN layer 344 is 2 μm.

The results regarding the warp of the wafer, which is the material of the light emitting element, and the in-plane light emission ratio of the wafer will be described with reference to FIGS. 4 and 5. The symbol A in FIG. 5 indicates the in-plane emission ratio (see the left axis) described later, and the symbol B indicates the warp of the wafer (see the right axis). As shown in FIGS. 4 and 5, the warpage of the wafer was 160 km ^-1 in Comparative Example, whereas it was suppressed to 77 km ^-1 in Example 1 and up to 89 km ^-1 in Example 2. It was suppressed.

Further, as the warp of the wafer is suppressed, the ratio of the number of light emitting elements that emit light with an intensity equal to or higher than a predetermined light emission intensity to the total number of light emitting elements that can be obtained from one wafer (hereinafter, "in-plane light emission"). (Also referred to as “ratio”) was 16% in Comparative Example, improved to 55% in Example 1, and improved to 52% in Example 2. In this embodiment, the predetermined emission intensity was set to 4.2 mW.

As described above, the warp of the light emitting element 1 of the first embodiment is suppressed to about 48% of the warp of the light emitting element of the comparative example, and the warp of the light emitting element 1 of the second embodiment is about the warp of the light emitting element of the comparative example. It was suppressed to 56%. Further, the in-plane light emitting ratio of the light emitting element 1 of Example 1 is about 3.8 times the in-plane light emitting ratio of the light emitting element of Comparative Example, and the in-plane light emitting ratio of the light emitting element 1 of Example 2 is the comparative example. The ratio of in-plane light emission of the light emitting element was about 3.2 times. As described above, it has been clarified by the present invention that the warp of the light emitting element 1 is suppressed and the variation in the in-plane portion of the light emitting intensity is increased. As a result, it is possible to make it difficult for the processing of the light emitting element to be hindered, and it is possible to suppress a decrease in the yield of the light emitting element.

<Modification example>
FIG. 3 is a graph schematically showing an example of the Al composition ratio of the n-type clad layer of the light emitting device according to the modified example. As shown in FIG. 3, the second Al composition ratio u may be set to a value equal to the first Al composition ratio q.

[Second Embodiment]
FIG. 6 is a graph schematically showing a modification of the Al composition ratio of the n-type clad layer of the light emitting device 1 according to the second embodiment of the present invention. The light emitting device 1 according to the second embodiment is different from the light emitting device 1 according to the first embodiment in that it includes a fourth AlGaN layer 36 described later. Hereinafter, the same components as those of the first embodiment will be referred to with the same reference numerals, duplicated description will be omitted, and the points different from those of the first embodiment will be mainly described.

As shown in FIG. 6, the n-type clad layer 30 of the light emitting element 1 further includes a fourth AlGaN layer 36 located on the buffer layer 34. The fourth AlGaN layer 36 is formed by Al _w Ga _1-w N (0 <w ≦ v <u ≦ q ≦ 1) having a fourth Al composition ratio w equal to or less than the third Al composition ratio v. There is.

The fourth AlGaN layer 36 has a thickness t ₄ of 2.0 μm or less. That is, t ₄ can take a value in the range of 0 ≦ t ₄ ≦ 2.0 μm.

Although not shown, the fourth Al composition ratio w may be set to a value equal to the third Al composition ratio v.

Even in the above manner, the warp of the wafer can be suppressed as in the light emitting element 1 according to the first embodiment. In addition, the in-plane distribution of emission intensity can be improved. As a result, it is possible to prevent the processing of the light emitting element from being hindered, and it is possible to suppress a decrease in the yield of the light emitting element.

(Actions and effects of embodiments)
As described above, in the light emitting element 1 according to the first embodiment of the present invention, its modifications, and the second embodiment, the n-type clad layer 30 is located on the base structure portion 2 side. Al located between the first AlGaN layer 32 formed of n-type AlGaN having the first Al composition ratio, the first AlGaN layer 32 and the multiple quantum well layer, and equal to or less than the first Al composition ratio. It has a buffer layer 34 in which a plurality of layers 342 and 344 formed of AlGaN having a composition ratio are alternately laminated. As a result, the warp of the wafer, which is the material of the light emitting element 1, is suppressed, and the in-plane distribution of the light emitting intensity can be improved.

(Summary of embodiments)
Next, the technical idea grasped from the embodiment described above will be described with reference to the reference numerals and the like in the embodiment. However, the respective reference numerals and the like in the following description are not limited to the members and the like in which the components within the scope of the claims are specifically shown in the embodiment.

[1] An n-type clad layer (30) formed of n-type AlGaN located on the base structure portion (2) including the substrate (10), and a plurality of n-type clad layers (30) located on the n-type clad layer (30). A nitride semiconductor light emitting device (1) including a multiple quantum well layer in which a barrier layer (52a, 52b, 52c) and a plurality of well layers (54a, 54b, 54c) are alternately laminated in this order. The n-type clad layer (30) is located on the base structure portion (2) side and has a first AlGaN layer (32) formed of n-type AlGaN having a first Al composition ratio (q). , A plurality of layers formed of AlGaN having an Al composition ratio of the first Al composition ratio (q) or less, which are located between the first AlGaN layer (32) and the multiple quantum well layer, alternate. A nitride semiconductor light emitting device, comprising a buffer layer (34) laminated on the above.
[2] The nitride semiconductor light emitting device according to the above [1], wherein the buffer layer (34) is formed by alternately stacking two types of layers formed of AlGaN having different Al composition ratios. (1).
[3] The two types of layers are a second AlGaN layer (342) containing AlGaN having a second Al composition ratio (u) equal to or lower than the first Al composition ratio, and the second Al composition ratio. The nitride semiconductor light emitting device (1) according to the above [2], which includes a third AlGaN layer (344) containing AlGaN having a third Al composition ratio (v) smaller than that.
[4] The nitride semiconductor light emitting device (1) according to the above [3], wherein the second AlGaN layer (342) is formed on the first AlGaN layer (32).
[5] The buffer layer (34) includes a plurality of the second AlGaN layer (342) and the plurality of the third AlGaN layer (344) from the first AlGaN layer (32) side. The nitride semiconductor light emitting device according to the above [4], which includes multiple layers in which L layers are alternately laminated in this order toward the multiple quantum well layer side.
[6] The nitride semiconductor light emitting device according to the above [4] or [5], wherein the second Al composition ratio (u) is a value substantially equal to the first Al composition ratio (q).
[7] The third AlGaN layer (344) has a thickness (t ₃ ) larger than the thickness (t ₂ ) of the second AlGaN layer (342), from [3] to [6]. The nitride semiconductor light emitting device (1) according to any one of the above.
[8] The nitride semiconductor light emitting device according to any one of [1] to [7], wherein the first AlGaN layer (32) has a thickness (t ₁ ) of 1.5 micrometers or less. Element (1).
[9] The nitride semiconductor light emitting device (1) according to any one of the above [1] to [8], wherein the buffer layer (34) has a thickness of 4.0 micrometers or less.
[10] The n-type clad layer (30) is located on the buffer layer (34) and has an n-type having a fourth Al composition ratio (w) equal to or less than the third Al composition ratio (v). The nitride semiconductor light emitting device (1) according to any one of the above [1] to [9], further including a fourth AlGaN (36) layer formed of AlGaN.
[11] The nitride semiconductor light emitting device (1) according to the above [10], wherein the fourth AlGaN layer (36) has a thickness (t ₄ ) of 2.0 micrometers or less.
[12] The nitride semiconductor light emitting device according to [1] 0 or [11], wherein the fourth Al composition ratio (w) is substantially equal to the third Al composition ratio (v). 1).
[13] A step of forming an n-type clad layer (30) having an n-type AlGaN located on the base structure portion (2) including the substrate (10), and a step of forming the n-type clad layer (30) located on the n-type clad layer (30). A nitride semiconductor light emitting device (including a step of forming a multiple quantum well layer in which a plurality of barrier layers (52a, 52b, 52c) and a plurality of well layers (54a, 54b, 54c) are alternately laminated in this order. In the manufacturing method of 1), the step of forming the n-type clad layer (30) is located on the base structure portion (2) side and has the first Al composition ratio (q). Located between the step of forming the first AlGaN layer (32) including the first AlGaN layer (32) and the first AlGaN layer (32) and the multiple quantum well layer, the first Al composition ratio (q) or less. A method for manufacturing a nitride semiconductor light emitting device (1), comprising a step of forming a buffer layer (34) in which a plurality of layers containing AlGaN having an Al composition ratio are alternately laminated.

1 ... Nitride semiconductor light emitting device (light emitting element)
2 ... Underlayer structure 10 ... Substrate 22 ... Buffer layer 30 ... n-type clad layer 30a ... Exposed surface 32 ... First AlGaN layer 34 ... Buffer layer 342 ... Second AlGaN layer 344 ... Third AlGaN layer 36 ... Third AlGaN layer 50 ... Active layer 52, 52a, 52b, 52c ... Barrier layer 54, 54a, 54b, 54c ... Well layer 60 ... Electronic block layer 70 ... p-type clad layer 80 ... p-type contact layer 90 ... n-side electrode 92 ... p-side electrode L ... Number of stacks t ₁ ... Thickness of first AlGaN layer t ₂ ... Thickness of second AlGaN layer t ₃ ... Thickness of third AlGaN layer t ₄ ... Fourth AlGaN layer Thickness q ... 1st Al composition ratio u ... 2nd Al composition ratio v ... 3rd Al composition ratio w ... 4th Al composition ratio

Claims (10)

An n-type clad layer formed of n-type AlGaN located on the underlying structure including the substrate, and an n-type clad layer.
A nitride semiconductor light-emitting device including a multiple quantum well layer in which a plurality of barrier layers and a plurality of well layers are alternately laminated in this order, which are located on the n-type clad layer.
The n-type clad layer is
A first AlGaN layer located on the base structure side and formed of an n-type AlGaN having a first Al composition ratio,
A buffer layer in which a plurality of layers formed of AlGaN having an Al composition ratio equal to or lower than that of the first Al composition ratio are alternately laminated, located between the first AlGaN layer and the multiple quantum well layer. Equipped with
The buffer layer is formed by alternately laminating two types of layers formed of AlGaN having different Al composition ratios.
The two types of layers are a second AlGaN layer containing AlGaN having a second Al composition ratio equal to or lower than the first Al composition ratio, and a third Al composition ratio smaller than the second Al composition ratio. A third AlGaN layer containing AlGaN and
The third AlGaN layer has a thickness larger than the thickness of the second AlGaN layer.
Nitride semiconductor light emitting device. The second AlGaN layer is formed on the first AlGaN layer.
The nitride semiconductor light emitting device according to claim 1 . The buffer layer is
A plurality of the second AlGaN layer and the plurality of the third AlGaN layers are alternately laminated in this order from the first AlGaN layer side toward the multiple quantum well layer side. Including multiple layers,
The nitride semiconductor light emitting device according to claim 2 . The second Al composition ratio is a value equal to the first Al composition ratio.
The nitride semiconductor light emitting device according to claim 2 or 3 . The first AlGaN layer has a thickness of 1.5 micrometers or less.
The nitride semiconductor light emitting device according to any one of claims 1 to 4 . The buffer layer has a thickness of 4.0 micrometers or less.
The nitride semiconductor light emitting device according to any one of claims 1 to 5 . The n-type clad layer further includes a fourth AlGaN layer located on the buffer layer and formed of n-type AlGaN having a fourth Al composition ratio equal to or lower than the third Al composition ratio.
The nitride semiconductor light emitting device according to any one of claims 1 to 6 . The fourth AlGaN layer has a thickness of 2.0 micrometers or less.
The nitride semiconductor light emitting device according to claim 7 . The fourth Al composition ratio is a value equal to the third Al composition ratio.
The nitride semiconductor light emitting device according to claim 7 . A step of forming an n-type clad layer having an n-type AlGaN located on a base structure including a substrate, and a step of forming the n-type clad layer.
A method for manufacturing a nitride semiconductor light emitting device, which comprises a step of forming a multiple quantum well layer in which a plurality of barrier layers and a plurality of well layers are alternately laminated in this order, which are located on the n-type clad layer. hand,
The step of forming the n-type clad layer is
A step of forming a first AlGaN layer containing an n-type AlGaN having a first Al composition ratio, which is located on the base structure side.
A buffer layer is formed between the first AlGaN layer and the multiple quantum well layer, in which a plurality of layers containing AlGaN having an Al composition ratio equal to or lower than the first Al composition ratio are alternately laminated. With the process ,
In the step of forming the buffer layer, two types of layers formed of AlGaN having different Al composition ratios are alternately laminated.
The two types of layers are a second AlGaN layer containing AlGaN having a second Al composition ratio equal to or lower than the first Al composition ratio, and a third Al composition ratio smaller than the second Al composition ratio. A third AlGaN layer containing AlGaN and
In the step of forming the third AlGaN layer, the third AlGaN layer is formed so that the thickness of the formed third AlGaN layer is larger than the thickness of the second AlGaN layer. Ru,
A method for manufacturing a nitride semiconductor light emitting device.

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