Light-emitting element and light-emitting device

Abstract

Provided are a light-emitting element and a light-emitting device with which leakage current flowing between electrodes of a plurality of light-emitting sections can be reduced. The third nitride semiconductor layer of the second light-emitting portion includes a first layer, a second layer located between the first layer and the second nitride semiconductor layer of the first light-emitting portion, and a third layer located between the first layer and the second active layer of the second light-emitting portion. The first layer contains at least one element selected from the group consisting of Be, Mg, Ca, Fe, Zn, and C. The third layer is thicker than the second layer. The first electrode is connected to the first nitride semiconductor layer of the first light-emitting part, the second electrode is connected to the third layer, the third electrode is connected to the second layer, and the fourth electrode is connected to the fourth nitride semiconductor layer of the second light-emitting part.

Description

Technical Field

[0001] The present invention relates to a light-emitting element and a light-emitting device. Background Art

[0002] For example, as shown in Patent Document 1, there is a light-emitting element in which a plurality of active layers are stacked on a substrate through a tunneling junction layer.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: European Patent Application Publication No. 4086964 Specification Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a light-emitting element and a light-emitting device capable of reducing leakage current flowing between electrodes of a plurality of light-emitting portions.

[0008] Means for Solving the Problems

[0009] According to one aspect of the present invention, a light-emitting element includes: a first light-emitting portion having a first nitride semiconductor layer containing a first conductivity type impurity, a second nitride semiconductor layer containing a second conductivity type impurity, and a first active layer located between the first nitride semiconductor layer and the second nitride semiconductor layer; a second light-emitting portion located on the second nitride semiconductor layer and having a third nitride semiconductor layer, a fourth nitride semiconductor layer containing a second conductivity type impurity, and a second active layer located between the third nitride semiconductor layer and the fourth nitride semiconductor layer; a first electrode; a second electrode; a third electrode; and a fourth electrode, wherein the third nitride semiconductor layer has a first layer, a second layer containing a first conductivity type impurity and located between the second nitride semiconductor layer and the first layer, and a third layer containing a first conductivity type impurity and located between the first layer and the second active layer, wherein the first layer contains at least one selected from Be, Mg, Ca, Fe, Zn, and C; the thickness of the third layer is greater than that of the second layer; the first electrode is connected to the first nitride semiconductor layer; the second electrode is connected to the third layer; the third electrode is connected to the second layer; and the fourth electrode is connected to the fourth nitride semiconductor layer.

[0010] According to one aspect of the present invention, a light-emitting element includes: a first structure; a second structure; and a third structure. The first structure has: a first stacked portion; a first electrode connected to the first nitride semiconductor layer; and a second electrode connected to the third nitride semiconductor layer. The first stacked portion has: a first nitride semiconductor layer containing a first-conductivity-type impurity, a second nitride semiconductor layer containing a second-conductivity-type impurity, a first active layer located between the first nitride semiconductor layer and the second nitride semiconductor layer, and a third nitride semiconductor layer disposed on the second nitride semiconductor layer and containing a first-conductivity-type impurity. The second structure has: a second stacked portion; a third electrode connected to the third nitride semiconductor layer; and a fourth electrode connected to the fifth nitride semiconductor layer. The second stacked portion has: the first stacked portion, a fourth nitride semiconductor layer containing a second-conductivity-type impurity, a second active layer located between the third nitride semiconductor layer and the fourth nitride semiconductor layer, and a fifth nitride semiconductor layer disposed on the fourth nitride semiconductor layer and containing a first-conductivity-type impurity. The third structure has: a third stacked portion; a fifth electrode connected to the fifth nitride semiconductor layer; and a sixth electrode connected to the sixth nitride semiconductor layer. The third stacked portion has: the first stacked portion, the second stacked portion, a sixth nitride semiconductor layer containing a second-conductivity-type impurity, and a third active layer located between the fifth nitride semiconductor layer and the sixth nitride semiconductor layer. The third nitride semiconductor layer of the second structure has: a first layer, a second layer located between the second nitride semiconductor layer and the first layer, and a third layer located between the first layer and the second active layer. The first layer contains at least one selected from Be, Mg, Ca, Fe, Zn, and C. The thickness of the third layer is greater than that of the second layer. The fifth nitride semiconductor layer of the third structure has: a fourth layer, a fifth layer located between the fourth nitride semiconductor layer and the fourth layer, and a sixth layer located between the fourth layer and the third active layer. The fourth layer contains at least one selected from Be, Mg, Ca, Fe, Zn, and C. The thickness of the sixth layer is greater than that of the fifth layer. The first stacked portion of the first structure is a first light-emitting portion; the second stacked portion of the second structure is a second light-emitting portion; and the third stacked portion of the third structure is a third light-emitting portion.

[0011] According to one aspect of the present invention, a light-emitting device does not include a wavelength conversion member containing a phosphor, and the light-emitting device includes: a wiring substrate having a first wiring portion that supplies current between the third electrode and the first electrode, and a second wiring portion that supplies current between the fourth electrode and the second electrode, and one or more light-emitting elements according to any one of claims 1 to 3 disposed on the wiring substrate.

[0012] Effects of the Invention

[0013] According to the present invention, a light-emitting element and a light-emitting device that reduce leakage current flowing between electrodes of a plurality of light-emitting portions can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic cross-sectional view of the light-emitting element according to the first embodiment.

[0015] Figure 2A is a schematic cross-sectional view of a part of the light-emitting element according to the first embodiment.

[0016] Figure 2B is a schematic cross-sectional view of a part of the light-emitting element according to the first embodiment.

[0017] Figure 3A is a schematic cross-sectional view of a part of the light-emitting element according to the first embodiment.

[0018] Figure 3B is a schematic cross-sectional view of a part of the light-emitting element according to the first embodiment.

[0019] Figure 4 is a schematic cross-sectional view of the light-emitting element according to the second embodiment.

[0020] Figure 5A is a schematic cross-sectional view of a part of the light-emitting element according to the second embodiment.

[0021] Figure 5B is a schematic cross-sectional view of a part of the light-emitting element according to the second embodiment.

[0022] Figure 6A is a schematic cross-sectional view of a part of the light-emitting element according to the second embodiment.

[0023] Figure 6B is a schematic cross-sectional view of a part of the light-emitting element according to the second embodiment.

[0024] Figure 7 is a schematic cross-sectional view of the light-emitting device according to the embodiment.

[0025] Figure 8 is a schematic cross-sectional view for explaining one process of the method for manufacturing the light-emitting element according to the first embodiment.

[0026] Figure 9 It is a schematic cross-sectional view showing one process of the manufacturing method of the light-emitting element according to the first embodiment.

[0027] Figure 10 It is a schematic cross-sectional view showing one process of the manufacturing method of the light-emitting element according to the first embodiment.

[0028] Figure 11 It is a schematic cross-sectional view showing one process of the manufacturing method of the light-emitting element according to the first embodiment.

[0029] Figure 12 It is a schematic cross-sectional view showing one process of the manufacturing method of the light-emitting element according to the first embodiment.

[0030] Figure 13 It is a schematic cross-sectional view showing one process of the manufacturing method of the light-emitting element according to the first embodiment.

[0031] Figure 14 It is a schematic cross-sectional view of the light-emitting element of the modified example of the first embodiment.

[0032] Figure 15 It is a graph showing an example of the operation of the current density with respect to the voltage in the second light-emitting portion of the light-emitting element according to the first embodiment.

[0033] Figure 16 It shows for having Figure 9 A graph showing an example of SIMS analysis of a sample of a wafer having the layer structure shown.

[0034] Symbol description

[0035] 1 to 3 light-emitting elements

[0036] 10 First nitride semiconductor layer

[0037] 20 Second nitride semiconductor layer

[0038] 30 Third nitride semiconductor layer

[0039] 31 First layer

[0040] 32 Second layer

[0041] 32A First GaN layer

[0042] 32B Second GaN layer

[0043] 32C First AlGaN layer

[0044] 33 Third layer

[0045] 33A Third GaN layer

[0046] 33B 4th GaN layer

[0047] 33C 2nd AlGaN layer

[0048] 40 4th nitride semiconductor layer

[0049] 50 5th nitride semiconductor layer

[0050] 60 6th nitride semiconductor layer

[0051] 61 1st active layer

[0052] 62 2nd active layer

[0053] 63 3rd active layer

[0054] 64 4th layer

[0055] 65 5th layer

[0056] 66 6th layer

[0057] 70 7th nitride semiconductor layer

[0058] 71 1st electrode

[0059] 72 2nd electrode

[0060] 73 3rd electrode

[0061] 74 4th electrode

[0062] 75 5th electrode

[0063] 76 6th electrode

[0064] 80 8th nitride semiconductor layer

[0065] 100 Substrate

[0066] 101 1st light-emitting part

[0067] 102 2nd light-emitting part

[0068] 103 3rd light-emitting part

[0069] 201 1st stacked part

[0070] 202 2nd stacked part

[0071] 203 3rd stacked part

[0072] 210 1st nitride semiconductor layer

[0073] 220 2nd nitride semiconductor layer

[0074] 230 3rd nitride semiconductor layer

[0075] Layer 1 of 231

[0076] Layer 2 of 232

[0077] Layer 3 of 233

[0078] First GaN layer of 233A

[0079] Second GaN layer of 233B

[0080] First AlGaN layer of 233C

[0081] Fourth nitride semiconductor layer of 240

[0082] Fifth nitride semiconductor layer of 250

[0083] Layer 4 of 254

[0084] Layer 5 of 255

[0085] Layer 6 of 256

[0086] Third GaN layer of 256A

[0087] Fourth GaN layer of 256B

[0088] Second AlGaN layer of 256C

[0089] Sixth nitride semiconductor layer of 260

[0090] First active layer of 271

[0091] Second active layer of 272

[0092] Third active layer of 273

[0093] First electrode of 301

[0094] Second electrode of 302

[0095] Third electrode of 303

[0096] Fourth electrode of 304

[0097] Fifth electrode of 305

[0098] Sixth electrode of 306

[0099] First structure of 401

[0100] Second structure of 402

[0101] Third structure of 403

[0102] Light-emitting device of 500

[0103] Wiring substrate of 600

[0104] 601 Insulating substrate

[0105] 611 First wiring portion

[0106] 612 Second wiring portion

[0107] 700 Joining member Detailed implementation manners

[0108] Hereinafter, the implementation manners will be described with reference to the accompanying drawings. Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the implementation manners are not limited thereto, but are merely illustrative examples. It should be noted that, for the sake of clear description, the sizes, positional relationships, etc. of the components shown in the respective drawings are sometimes exaggerated. In addition, in the following description, the same names and symbols denote the same or the same nature components, and their detailed descriptions are appropriately omitted. In addition, as sectional views, sometimes only the end faces showing the cut surfaces are shown.

[0109] In the following description, there are cases where terms showing specific directions or positions (for example, "upper", "lower", and other terms including them) are used. However, these terms are only used to facilitate understanding of the relative directions or positions in the accompanying drawings. In the accompanying drawings referred to, when the relative directions or positional relationships indicated by the terms "upper", "lower", etc. are the same, then in the drawings other than the present disclosure, actual products, etc., the configurations may be different from the accompanying drawings referred to. The positional relationships shown as "upper (or lower)" in this specification include, for example, when assuming that there are two components, the case where the two components are in contact, and the case where the two components are not in contact (one component is located above (or below) the other component). In addition, in this specification, the thickness of a layer represents the maximum thickness of the layer.

[0110] In this specification, the semiconductor layer and the active layer include nitride semiconductors. The nitride semiconductors include, for example, In x Al y Ga 1-x-y All semiconductors with composition ratios x and y varying within their respective ranges in the chemical formula represented by N(0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). In addition, with respect to the above chemical formula, substances further including group V elements other than N (nitrogen), and substances further including various elements added for controlling various physical properties such as conductivity are also included in the meaning of "nitride semiconductor".

[0111] In this specification, the first conductivity type is taken as n-type and the second conductivity type is taken as p-type for description. As the first conductivity type impurity (i.e., n-type impurity), for example, Si (silicon) or Ge (germanium) can be used. As the second conductivity type impurity (i.e., p-type impurity), for example, Mg (magnesium) can be used. It should be noted that the first conductivity type can be p-type and the second conductivity type can be n-type. In this case, in the electrodes described later, the cathode can be replaced with the anode. Additionally, the anode can also be replaced with the cathode.

[0112] [First Embodiment]

[0113] Refer to Figures 1 to 3B , and the light-emitting element 1 of the first embodiment will be described. The light-emitting element 1 is a light-emitting diode.

[0114] As Figure 1 shown, the light-emitting element 1 includes: a first light-emitting portion 101, a second light-emitting portion 102, a first electrode 71, a second electrode 72, a third electrode 73, and a fourth electrode 74.

[0115] <First Light-Emitting Portion 101>

[0116] The first light-emitting portion 101 has: a first nitride semiconductor layer 10 containing a first conductivity type impurity, a second nitride semiconductor layer 20 containing a second conductivity type impurity, and a first active layer 61 located between the first nitride semiconductor layer 10 and the second nitride semiconductor layer 20. The first active layer 61 is a light-emitting layer that emits light and has, for example, an MQW (Multiple Quantum Well) structure including a plurality of barrier layers and a plurality of well layers. The well layer of the first active layer 61 contains, for example, In x1 Ga 1-x1 N (0 ≤ x1 ≤ 1). The concentration of the first conductivity type impurity contained in the first nitride semiconductor layer 10 can be, for example, 1×10 18 cm -3 or more and 1×10 19 cm -3 or less. The concentration of the second conductivity type impurity contained in the second nitride semiconductor layer 20 can be, for example, 1×10 18 cm -3 or more and 1×10 20 cm -3 or less.

[0117] The first nitride semiconductor layer 10 has a first surface 10A on the side opposite to the interface with the first active layer 61. The light-emitting element 1 may have a substrate on the first surface 10A side. In addition, the first nitride semiconductor layer 10 has: a first active layer 61, a second nitride semiconductor layer 20, and a first connection surface 10B exposed from the second light-emitting portion 102. The first connection surface 10B is located on the side opposite to the first surface 10A.

[0118] <The second light-emitting portion 102>

[0119] The second light-emitting portion 102 is located on the second nitride semiconductor layer 20 of the first light-emitting portion 101. The second light-emitting portion 102 has: a third nitride semiconductor layer 30 located on the second nitride semiconductor layer 20, a fourth nitride semiconductor layer 40 containing a second-conductive-type impurity, and a second active layer 62 located between the third nitride semiconductor layer 30 and the fourth nitride semiconductor layer 40. The second active layer 62 is a light-emitting layer that emits light and has, for example, an MQW structure. The well layer of the second active layer 62 contains, for example, In x2 Ga 1-x2 N (0 ≤ x2 ≤ 1). x2 can be larger than x1. In the case of an MQW structure, it is sufficient to have at least one layer with x2 > x1. Therefore, compared with the first active layer 61, the second active layer 62 can emit light of a different wavelength. The concentration of the second-conductive-type impurity contained in the fourth nitride semiconductor layer 40 can be, for example, 1 × 10 18 cm -3 or more and 1 × 10 20 cm -3 or less.

[0120] The third nitride semiconductor layer 30 has a second connection surface 30B and a third connection surface 30A. The second connection surface 30B and the third connection surface 30A are exposed from the second active layer 62 and the fourth nitride semiconductor layer 40. The third nitride semiconductor layer 30 has: a first layer 31, a second layer 32, and a third layer 33. The structures of each of the layers 31 to 33 will be described in detail below. The second connection surface 30B is a surface of a part of the third layer 33. The third connection surface 30A is a surface of a part of the second layer 32.

[0121] The fourth nitride semiconductor layer 40 has a fourth connection surface 40A on the side opposite to the interface with the second active layer 62.

[0122] <The first electrode 71>

[0123] The first electrode 71 is disposed on the first connection surface 10B of the first nitride semiconductor layer 10 and is electrically connected to the first nitride semiconductor layer 10. As the material of the first electrode 71, for example, at least one selected from titanium, aluminum, platinum, rhodium, ruthenium, and gold can be used. The first electrode 71, for example, can use a combination of titanium, aluminum, and platinum. It should be noted that the other electrode materials described below can also use, for example, the same materials as the first electrode 71.

[0124] <The second electrode 72>

[0125] The second electrode 72 is disposed on the second connection surface 30B of the third nitride semiconductor layer 30 and is electrically connected to the third layer 33 of the third nitride semiconductor layer 30.

[0126] <The third electrode 73>

[0127] The third electrode 73 is disposed on the third connection surface 30A of the third nitride semiconductor layer 30 and is electrically connected to the second layer 32 of the third nitride semiconductor layer 30.

[0128] <The fourth electrode 74>

[0129] The fourth electrode 74 is disposed on the fourth connection surface 40A of the fourth nitride semiconductor layer 40 and is electrically connected to the fourth nitride semiconductor layer 40.

[0130] The third electrode 73 functions as the anode of the first light-emitting portion 101. The first electrode 71 functions as the cathode of the first light-emitting portion 101. Current is supplied to the first active layer 61 through the third electrode 73 and the first electrode 71, and the first active layer 61 emits light. The emission peak wavelength of the first active layer 61 is the first wavelength. The first wavelength is, for example, 360 nm or more and 550 nm or less, preferably 440 nm or more and 470 nm or less. It should be noted that the range of the first wavelength is not limited to this.

[0131] The fourth electrode 74 functions as the anode of the second light-emitting portion 102. The second electrode 72 functions as the cathode of the second light-emitting portion 102. Current is supplied to the second active layer 62 through the fourth electrode 74 and the second electrode 72, and the second active layer 62 emits light. The emission peak wavelength of the second active layer 62 is the second wavelength different from the first wavelength of the first active layer 61. The second wavelength is, for example, 450 nm or more and 700 nm or less, preferably 570 nm or more and 590 nm or less. It should be noted that the range of the second wavelength is not limited to this.

[0132] The light emitted from the first active layer 61 and the light emitted from the second active layer 62 are mainly led out to the outside of the light-emitting element 1 from the side of the first surface 10A of the first nitride semiconductor layer 10.

[0133] Regarding the light-emitting element 1, the following three states can be switched by controlling an external circuit: a first light-emitting state in which the first light-emitting unit 101 emits light and the second light-emitting unit 102 does not emit light, a second light-emitting state in which the second light-emitting unit 102 emits light and the first light-emitting unit 101 does not emit light, and a third light-emitting state in which the first light-emitting unit 101 and the second light-emitting unit 102 emit light simultaneously.

[0134] In the third state, the light-emitting element 1 emits visible light that is a mixture of light of a first wavelength emitted from the first active layer 61 and light of a second wavelength emitted from the second active layer 62. The light-emitting element 1 emits, for example, white light. The color temperature (including the correlated color temperature) of the white light is, for example, 3000 K or higher and 7000 K or lower.

[0135] When causing the first active layer 61 to emit light, a positive potential is applied to the third electrode 73, a potential lower than that of the third electrode 73 is applied to the first electrode 71, and a reverse voltage is applied to the pn junction between the second nitride semiconductor layer 20 containing a second conductivity type impurity (p-type impurity) and the second layer 32 containing a first conductivity type impurity (n-type impurity). According to the present embodiment, the light-emitting element 1 includes a tunneling junction between the second nitride semiconductor layer 20 and the second layer 32. The width of the depletion layer formed by the pn junction is reduced by increasing the impurity concentration in the pn junction between the second nitride semiconductor layer 20 and the second layer 32. As a result, electrons present in the valence band of the p-type second nitride semiconductor layer 20 can tunnel into the conduction band of the n-type second layer 32, and current can easily flow from the third electrode 73 to the first electrode 71.

[0136] The second nitride semiconductor layer 20 and the second layer 32 may be directly bonded. Alternatively, the light-emitting element 1 may further include a fifth nitride semiconductor layer 50 located between the second nitride semiconductor layer 20 and the second layer 32. The fifth nitride semiconductor layer 50 contains a first conductivity type impurity (n-type impurity) and forms an interface (pn junction) with the second nitride semiconductor layer 20. The maximum value of the concentration of the first conductivity type impurity contained in the fifth nitride semiconductor layer 50 is higher than the maximum value of the concentration of the first conductivity type impurity contained in the first nitride semiconductor layer 10 and the maximum value of the concentration of the first conductivity type impurity contained in the third nitride semiconductor layer 30. As a result, the width of the depletion layer formed by the pn junction between the second nitride semiconductor layer 20 and the fifth nitride semiconductor layer 50 can be reduced, and electrons present in the valence band of the second nitride semiconductor layer 20 can easily tunnel into the second layer 32. The concentration of the first conductivity type impurity contained in the fifth nitride semiconductor layer 50 may be, for example, 1×10 18 cm -3 or more and 1×10 20 cm -3 or less, or 1×10 18 cm-3 or more and 1×10 19 cm -3 or less.

[0137] (The third nitride semiconductor layer 30)

[0138] The first layer 31, the second layer 32, and the third layer 33 of the third nitride semiconductor layer 30 will be described in detail.

[0139] The first layer 31 is located between the second layer 32 and the third layer 33. The first layer 31 contains at least one selected from Be (beryllium), Mg (magnesium), Ca (calcium), Fe (iron), Zn (zinc), and C (carbon). Hereinafter, at least one selected from Be, Mg, Ca, Fe, Zn, and C will be simply referred to as an additive. By including such an additive in the first layer 31, the resistivity of the first layer 31 is higher than the resistivity of the second layer 32 and the resistivity of the third layer 33. Therefore, it is difficult for current to take a path from the third electrode 73, which is the anode of the first light-emitting unit 101, to the second electrode 72, which is the cathode of the second light-emitting unit 102 (schematically indicated by arrow A in Figure 1 ). Therefore, the leakage current flowing between the third electrode 73 (anode) of the first light-emitting unit 101 and the second electrode 72 (cathode) of the second light-emitting unit 102 can be reduced.

[0140] The concentration of the additive contained in the first layer 31 is higher than the concentration of the additive contained in the second layer 32 and the concentration of the additive contained in the third layer 33. The first layer 31 may further contain a first-conductivity-type impurity. The concentration of the additive contained in the first layer 31 is higher than the concentration of the first-conductivity-type impurity contained in the first layer 31. Therefore, electrons and holes compensate each other, the first layer 31 can have a higher resistance, and the above-mentioned leakage current can be further reduced.

[0141] The thickness of the first layer 31 is thinner than the thickness of the second layer 32 and the thickness of the third layer 33. The thickness of the first layer 31 is, for example, 100 nm or more and 1000 nm or less, or 200 nm or more and 600 nm or less. Thereby, while increasing the resistance of the first layer 31, the absorption of light caused by the first layer 31 can be reduced.

[0142] The first layer 31 preferably contains C as the above-mentioned additive. As described below, the first layer 31 can be formed by the MOCVD (metalorganic chemical vapor deposition) method. According to the conditions at this time, the C concentration contained in the first layer 31 can be adjusted more easily. In addition, compared with other additives, when C is introduced into the first layer 31, it is easy to improve the flatness of the first layer 31. The C concentration of the first layer 31 is higher than the C concentrations of the second layer 32 and the third layer 33. Thereby, the leakage current flowing between the electrodes of the plurality of light-emitting portions can be reduced. The C concentration of the first layer 31 is, for example, 1×10 18 cm -3 or more and 1×10 21 cm -3 or less, preferably 1×10 19 cm -3 or more and 1×10 20 cm -3 or less. Thereby, while reducing the influence of light absorption, the leakage current flowing between the electrodes of the plurality of light-emitting portions can be reduced.

[0143] The C concentration contained in the first layer 31 is higher than the concentration of the first conductive-type impurity (for example, Si) contained in the first layer 31. Therefore, the first layer 31 can have a higher resistance, and the above-mentioned leakage current can be further reduced. The C concentration contained in the first layer 31 can be 10 times or more and 1000 times or less, or 10 times or more and 100 times or less of the concentration of the first conductive-type impurity contained in the first layer 31. In addition, the difference between the C concentration and the Si concentration contained in the first layer 31 is, for example, 9×10 17 cm -3 or more and 1×10 20 cm -3 or less, preferably 1×10 19 cm -3 or more and 1×10 20 cm -3 or less. Thereby, the resistance of the first layer 31 can be further increased.

[0144] The second layer 32 is located between the second nitride semiconductor layer 20 and the first layer 31. When the light-emitting element 1 includes the above-mentioned fifth nitride semiconductor layer 50, the second layer 32 is located between the fifth nitride semiconductor layer 50 and the first layer 31. The second layer 32 contains a first conductive-type impurity. In addition, the second layer 32 may contain the above-mentioned additive. The concentration of the first conductive-type impurity contained in the second layer 32 is higher than the concentration of the additive contained in the second layer 32. Therefore, the resistance of the second layer 32 can be reduced, and the forward voltage of the first light-emitting portion 101 can be reduced. The concentration of the additive contained in the second layer 32 is, for example, 1×10 16 cm-3 above and 5×10 18 cm -3 below, 1×10 16 cm -3 above and 1×10 18 cm -3 below, or 1×10 16 cm -3 above and 1×10 17 cm -3 below. The thickness of the second layer 32 is, for example, 100 nm or more and 2000 nm or less.

[0145] The third layer 33 is located between the first layer 31 and the second active layer 62 and contains an impurity of the first conductivity type. In addition, the third layer 33 may contain the above-mentioned additive. The concentration of the impurity of the first conductivity type contained in the third layer 33 is higher than the concentration of the additive contained in the third layer 33. Therefore, the resistance of the third layer 33 can be reduced, and the forward voltage of the second light-emitting portion 102 can be reduced. The concentration of the additive contained in the third layer 33 is, for example, 1×10 16 cm -3 above and 5×10 18 cm -3 below, 1×10 16 cm -3 above and 1×10 18 cm -3 below, or 1×10 16 cm -3 above and 1×10 17 cm -3 below. The thickness of the third layer 33 is, for example, 100 nm or more and 2000 nm or less.

[0146] The thickness of the third layer 33 is greater than the thickness of the second layer 32. Thereby, the surface resistance of the third layer 33 can be reduced, the current can be more easily diffused, and the forward voltage of the second light-emitting portion 102 can be reduced. The crystal defects can be reduced by making the second layer 32 thinner. In addition, by making the second layer 32 thinner, when the second layer 32 is formed by the MOCVD method, the film formation time required can be reduced, and thus the thermal damage to the layer below the second layer 32 can be reduced.

[0147] The thickness of the third layer 33 can be, for example, 0.5 times or more and 1.2 times or less the thickness of the first nitride semiconductor layer 10. Thereby, a larger current can be injected into the second light-emitting portion 102 to improve the output. For example, when the thickness of the first nitride semiconductor layer 10 is 1 μm or more and 3 μm or less, the thickness of the third layer can be 0.5 μm or more and 3.6 μm or less, 1 μm or more and 2 μm or less.

[0148] The concentrations of the additives in the first layer 31, the second layer 32, and the third layer 33 can be analyzed by SIMS (Secondary Ion Mass Spectrometry). Similarly, the concentration of the first conductivity type impurity can also be analyzed by SIMS. In addition, for more detailed analysis, the observation of a cross-sectional view using TEM (Transmission Electron Microscope) and elemental analysis by EDX (Energy Dispersive X-ray Spectroscopy) can be used in combination.

[0149] As Figure 2A and Figure 2B shown, the second layer 32 may have a first GaN layer 32A, a second GaN layer 32B, and a first AlGaN layer 32C. The second GaN layer 32B is closer to the first layer 31 than the first GaN layer 32A. The second GaN layer 32B is located between the first AlGaN layer 32C and the first layer 31. The first AlGaN layer 32C is located between the first GaN layer 32A and the second GaN layer 32B. For example, the composition of the first AlGaN layer 32C may be Al x3 Ga 1-x3 N (0.05 < x3 ≤ 0.4, preferably 0.05 ≤ x3 ≤ 0.2). Thereby, the degradation of the quality of the first AlGaN layer 32C can be reduced. The resistivity of the first AlGaN layer 32C is higher than the resistivity of the first GaN layer 32A and the resistivity of the second GaN layer 32B. Similar to the first layer 31, such a first AlGaN layer 32C can function as a resistance layer for reducing the leakage current flowing between the third electrode 73 (anode) of the first light-emitting unit 101 and the second electrode 72 (cathode) of the second light-emitting unit 102.

[0150] In Figure 2A the example shown, the first AlGaN layer 32C has a third connection surface 30A on which the third electrode 73 is disposed. The third electrode 73 contacts the first AlGaN layer 32C on the third connection surface 30A and is electrically connected to the first AlGaN layer 32C. Thereby, the leakage current flowing between the third electrode 73 (anode) of the first light-emitting unit 101 and the second electrode 72 (cathode) of the second light-emitting unit 102 is reduced.

[0151] In Figure 2BIn the example shown, the first GaN layer 32A has a third connection surface 30A. The third electrode 73 contacts the first GaN layer 32A at the third connection surface 30A and is electrically connected to the first GaN layer 32A. The contact resistance between the third electrode 73 and the first GaN layer 32A can also be lower than the contact resistance between the third electrode 73 and the first AlGaN layer 32C. Therefore, while reducing the forward voltage for causing the first light-emitting unit 101 to emit light, the leakage current flowing between the third electrode 73 (anode) of the first light-emitting unit 101 and the second electrode 72 (cathode) of the second light-emitting unit 102 is reduced.

[0152] As Figure 3A and Figure 3B shown, the third layer 33 may have a third GaN layer 33A, a fourth GaN layer 33B, and a second AlGaN layer 33C. The fourth GaN layer 33B is farther from the first layer 31 than the third GaN layer 33A. The fourth GaN layer 33B is located between the second AlGaN layer 33C and the second active layer 62. The second AlGaN layer 33C is located between the third GaN layer 33A and the fourth GaN layer 33B. For example, the composition of the second AlGaN layer 33C may be Al x4 Ga 1-x4 N (0.05 ≤ x4 ≤ 0.4, preferably 0.05 ≤ x4 ≤ 0.2). Thereby, a decrease in the quality of the second AlGaN layer 33C can be reduced. The resistivity of the second AlGaN layer 33C is higher than the resistivity of the third GaN layer 33A and the resistivity of the fourth GaN layer 33B.

[0153] In Figure 3A the example shown, the second AlGaN layer 33C has a second connection surface 30B where the second electrode 72 is disposed. The second electrode 72 contacts the second AlGaN layer 33C at the second connection surface 30B and is electrically connected to the second AlGaN layer 33C. At this time, similar to the first layer 31, the second AlGaN layer 33C functions as a resistance layer for reducing the leakage current flowing between the third electrode 73 (anode) of the first light-emitting unit 101 and the second electrode 72 (cathode) of the second light-emitting unit 102. Therefore, the leakage current flowing between the third electrode 73 (anode) of the first light-emitting unit 101 and the second electrode 72 (cathode) of the second light-emitting unit 102 is reduced.

[0154] In Figure 3B the example shown, the third GaN layer 33A has a second connection surface 30B where the second electrode 72 is disposed. The second electrode 72 contacts the third GaN layer 33A at the second connection surface 30B and is electrically connected to the third GaN layer 33A. The contact resistance between the second electrode 72 and the third GaN layer 33A can be lower than the contact resistance between the second electrode 72 and the second AlGaN layer 33C.

[0155] The structure of Figure 3A or Figure 3B can be combined with the structure of Figure 2A . Alternatively, the structure of Figure 3A or Figure 3B can be combined with the structure of Figure 2B .

[0156] [Second Embodiment]

[0157] Referring to Figures 4 to 6B , the light-emitting element 2 of the second embodiment will be described.

[0158] As Figure 4 shown, the light-emitting element 2 includes: a first structure 401, a second structure 402, and a third structure 403.

[0159] [First Structure 401]

[0160] The first structure 401 has: a first stacked portion 201, a first electrode 301, and a second electrode 302.

[0161] (First Stacked Portion 201)

[0162] The first stacked portion 201 has: a first nitride semiconductor layer 210 containing a first conductive-type impurity, a second nitride semiconductor layer 220 containing a second conductive-type impurity, a first active layer 271 located between the first nitride semiconductor layer 210 and the second nitride semiconductor layer 220, and a third nitride semiconductor layer 230 disposed on the second nitride semiconductor layer 220 and containing a first conductive-type impurity. The second nitride semiconductor layer 220 is located between the first active layer 271 and the third nitride semiconductor layer 230. The first active layer 271 is a light-emitting layer that emits light and has, for example, a MQW structure. The first stacked portion 201 is a first light-emitting portion.

[0163] The first nitride semiconductor layer 210 has a first surface 210A on the opposite side of the interface with the first active layer 271. The light-emitting element 2 may have a substrate on the first surface 210A side. In addition, the first nitride semiconductor layer 210 has: the third nitride semiconductor layer 230, the second nitride semiconductor layer 220, and a first connection surface 210B exposed from the first active layer 271. The first connection surface 210B is located on the opposite side of the first surface 210A.

[0164] The third nitride semiconductor layer 230 has a third connection surface 230A on the opposite side of the interface with the second nitride semiconductor layer 220.

[0165] (First Electrode 301)

[0166] The first electrode 301 is disposed on the first connection surface 210B of the first nitride semiconductor layer 210 and is electrically connected to the first nitride semiconductor layer 210.

[0167] (The second electrode 302)

[0168] The second electrode 302 is disposed on the third connection surface 230A of the third nitride semiconductor layer 230 and is electrically connected to the third nitride semiconductor layer 230.

[0169] The second electrode 302 functions as the anode of the first structure 401. The first electrode 301 functions as the cathode of the first structure 401. By supplying current to the first active layer 271 from the second electrode 302 and the first electrode 301, the first active layer 271 of the first structure 401 emits light. The peak emission wavelength of the first active layer 271 of the first structure 401 is the first wavelength. The first wavelength is, for example, 440 nm or more and 470 nm or less. It should be noted that the range of the first wavelength is not limited to this.

[0170] <The second structure 402>

[0171] The second structure 402 includes a second stacked portion 202, a third electrode 303, and a fourth electrode 304.

[0172] (The second stacked portion 202)

[0173] The second stacked portion 202 includes a first stacked portion 201, a fourth nitride semiconductor layer 240 containing a second-conductive-type impurity, a second active layer 272 located between the third nitride semiconductor layer 230 and the fourth nitride semiconductor layer 240, and a fifth nitride semiconductor layer 250 disposed on the fourth nitride semiconductor layer 240 and containing a first-conductive-type impurity. The fourth nitride semiconductor layer 240 is located between the second active layer 272 and the fifth nitride semiconductor layer 250. The second active layer 272 is a light-emitting layer that emits light and has, for example, an MQW structure. The second stacked portion 202 is a second light-emitting portion.

[0174] The first stacked portion 201 of the first structure 401 and the first stacked portion 201 of the second structure 402 are separated from each other with the first groove 901 therebetween. The first connection surface 210B of the first structure 401 defines the bottom of the first groove 901. The width of the first groove 901 (i.e., the distance between the first stacked portion 201 of the first structure 401 and the first stacked portion 201 of the second structure 402) is, for example, 1 μm or more and 20 μm or less. For the light-emitting element 2 of the second embodiment, when the width of the first groove 901 becomes relatively small like this, the insulation between the plurality of light-emitting portions effectively functions. The same applies to the second groove 902 described later.

[0175] The third nitride semiconductor layer 230 of the second structure 402 has a third connection surface 230B. The third connection surface 230B is exposed from the second active layer 272, the fourth nitride semiconductor layer 240, and the fifth nitride semiconductor layer 250. The third nitride semiconductor layer 230 has: a first layer 231, a second layer 232, and a third layer 233. The structures of the respective layers 231 to 233 will be described in detail below. The third connection surface 230B is the surface of a part of the third layer 233.

[0176] The fifth nitride semiconductor layer 250 has a fourth connection surface 250A on the side opposite to the interface with the fourth nitride semiconductor layer 240.

[0177] (The third electrode 303)

[0178] The third electrode 303 is disposed on the third connection surface 230B of the third nitride semiconductor layer 230 and is electrically connected to the third nitride semiconductor layer 230.

[0179] (The fourth electrode 304)

[0180] The fourth electrode 304 is disposed on the fourth connection surface 250A of the fifth nitride semiconductor layer 250 and is electrically connected to the fifth nitride semiconductor layer 250.

[0181] The fourth electrode 304 functions as the anode of the second structure 402. The third electrode 303 functions as the cathode of the second structure 402. By supplying current to the second active layer 272 from the fourth electrode 304 and the third electrode 303, the second active layer 272 of the second structure 402 emits light. The emission peak wavelength of the second active layer 272 of the second structure 402 is the second wavelength. The second wavelength is, for example, 570 nm or more and 590 nm or less. Note that the range of the second wavelength is not limited to this.

[0182] <The third structure 403>

[0183] The third structure 403 has: a third stacked portion 203, a fifth electrode 305, and a sixth electrode 306.

[0184] (The third stacked portion 203)

[0185] The third stacked portion 203 has: a first stacked portion 201, a second stacked portion 202, a sixth nitride semiconductor layer 260 containing a second-conductivity-type impurity, and a third active layer 273 located between the fifth nitride semiconductor layer 250 and the sixth nitride semiconductor layer 260. The third active layer 273 is a light-emitting layer that emits light and has, for example, a MQW structure. The third stacked portion 203 is a third light-emitting portion.

[0186] The first stacked portion 201 of the second structure 402 and the first stacked portion 201 of the third structure 403 are separated from each other with the second groove 902 therebetween. The width of the second groove 902 (the distance between the first stacked portion 201 of the second structure 402 and the first stacked portion 201 of the third structure 403) is, for example, 1 μm or more and 20 μm or less.

[0187] The fifth nitride semiconductor layer 250 of the third structure 403 has a fifth connection surface 250B. The fifth connection surface 250B is exposed from the third active layer 273 and the sixth nitride semiconductor layer 260. The fifth nitride semiconductor layer 250 has a fourth layer 254, a fifth layer 255, and a sixth layer 256. The structures of the respective layers 254 to 256 will be described in detail below. The fifth connection surface 250B is the surface of a part of the sixth layer 256.

[0188] The sixth nitride semiconductor layer 260 has a sixth connection surface 260A located on the side opposite to the interface with the third active layer 273.

[0189] (The fifth electrode 305)

[0190] The fifth electrode 305 is disposed on the fifth connection surface 250B of the fifth nitride semiconductor layer 250 and is electrically connected to the fifth nitride semiconductor layer 250.

[0191] (The sixth electrode 306)

[0192] The sixth electrode 306 is disposed on the sixth connection surface 260A of the sixth nitride semiconductor layer 260 and is electrically connected to the sixth nitride semiconductor layer 260.

[0193] The sixth electrode 306 functions as the anode of the third structure 403. The fifth electrode 305 functions as the cathode of the third structure 403. Current is supplied to the third active layer 273 through the sixth electrode 306 and the fifth electrode 305, and the third active layer 273 of the third structure 403 emits light. The emission peak wavelength of the third active layer 273 of the third structure 403 is the third wavelength. The third wavelength is, for example, 590 nm or more and 770 nm or less. It should be noted that the range of the third wavelength is not limited to this.

[0194] The first wavelength of the light emitted by the first active layer 271 of the first structure 401, the second wavelength of the light emitted by the second active layer 272 of the second structure 402, and the third wavelength of the light emitted by the third active layer 273 of the third structure 403 are different from each other. For example, the first wavelength is shorter than the second wavelength, and the second wavelength is shorter than the third wavelength.

[0195] Light emitted from the first active layer 271 of the first structure 401, light emitted from the second active layer 272 of the second structure 402, and light emitted from the third active layer 273 of the third structure 403 are mainly extracted to the outside of the light-emitting element 2 from the first surface 210A side of the first nitride semiconductor layer 210.

[0196] In the light-emitting element 2, the first active layer 271 of the first structure 401, the second active layer 272 of the second structure 402, and the third active layer 273 of the third structure 403 can each emit light independently. In addition, the light emission of the first active layer 271 of the first structure 401, the second active layer 272 of the second structure 402, and the third active layer 273 of the third structure 403 can be controlled independently. Two of the first active layer 271 of the first structure 401, the second active layer 272 of the second structure 402, and the third active layer 273 of the third structure 403 can emit light simultaneously. In addition, the first active layer 271 of the first structure 401, the second active layer 272 of the second structure 402, and the third active layer 273 of the third structure 403 can all emit light simultaneously. For example, one pixel formed by combining the three primary colors of RGB can be constituted by the first structure 401, the second structure 402, and the third structure 403.

[0197] (The third nitride semiconductor layer 230 of the second structure 402)

[0198] The first layer 231, the second layer 232, and the third layer 233 of the third nitride semiconductor layer 230 of the second structure 402 will be described in detail.

[0199] The first layer 231 is located between the second layer 232 and the third layer 233. The first layer 231 contains the same additive as the first layer 31 of the first embodiment. By making the first layer 231 contain such an additive, the resistivity of the first layer 231 is higher than the resistivity of the second layer 232 and the resistivity of the third layer 233. Therefore, it is difficult for the current to take a path from the fourth electrode 304, which is the anode of the second structure 402, to the first electrode 301, which is the cathode of the first structure 401. Therefore, the leakage current flowing between the fourth electrode 304 (anode) of the second structure 402 and the first electrode 301 (cathode) of the first structure 401 can be reduced.

[0200] In addition, the first layer 231 can reduce the leakage current flowing between the second electrode 302, which is the anode of the first structure 401, and the third electrode 303, which is the cathode of the second structure 402.

[0201] In addition, the first layer 231 can reduce the leakage current flowing between the sixth electrode 306, which is the anode of the third structure 403, and the third electrode 303, which is the cathode of the second structure 402.

[0202] The concentration of the additive contained in the first layer 231 is higher than the concentration of the additive contained in the second layer 232 and the concentration of the additive contained in the third layer 233. The first layer 231 may further contain an impurity of the first conductivity type. The concentration of the additive contained in the first layer 231 is higher than the concentration of the impurity of the first conductivity type contained in the first layer 231. Thereby, the first layer 231 can have a higher resistance and further reduce the above-mentioned leakage current.

[0203] The thickness of the first layer 231 is thinner than the thickness of the second layer 232 and the thickness of the third layer 233. The thickness of the first layer 231 is, for example, 100 nm or more and 1000 nm or less.

[0204] As described above, from the viewpoints of ease of concentration adjustment and flatness, the first layer 231 preferably contains C as the above-mentioned additive. The C concentration of the first layer 231 is higher than the C concentration of the second layer 232 and the C concentration of the third layer 233. The C concentration of the first layer 231 is, for example, 1×10 18 cm -3 or more and 1×10 21 cm -3 or less, preferably 1×10 19 cm -3 or more and 1×10 20 cm -3 or less. Thereby, while reducing the influence of light absorption, the leakage current flowing between the electrodes of the plurality of light-emitting portions can be reduced.

[0205] The C concentration contained in the first layer 231 is higher than the concentration of the impurity of the first conductivity type (for example, Si) contained in the first layer 231. Thereby, the first layer 231 can have a higher resistance and further reduce the above-mentioned leakage current. The difference between the C concentration contained in the first layer 231 and the Si concentration contained in the first layer 231 is, for example, 9×10 17 cm -3 or more and 1×10 20 cm -3 or less, preferably 1×10 19 cm -3 or more and 1×10 20 cm -3 or less.

[0206] The second layer 232 is located between the second nitride semiconductor layer 220 and the first layer 231. The second layer 232 contains an impurity of a first conductivity type. In addition, the second layer 232 may contain the above-described additive. The concentration of the impurity of the first conductivity type contained in the second layer 232 is higher than the concentration of the additive contained in the second layer 232. Thereby, the resistance of the second layer 232 can be reduced, and thus the forward voltage of the second structure 402 can be reduced. The concentration of the additive contained in the second layer 232 is, for example, 1×10 16 cm -3 or more and 5×10 18 cm -3 or less, 1×10 16 cm -3 or more and 1×10 18 cm -3 or less, or 1×10 16 cm -3 or more and 1×10 17 cm -3 or less.

[0207] The third layer 233 is located between the first layer 231 and the second active layer 272 and contains an impurity of a first conductivity type. In addition, the third layer 233 may contain the above-described additive. The concentration of the impurity of the first conductivity type contained in the third layer 233 is higher than the concentration of the additive contained in the third layer 233. Thereby, the resistance of the third layer 233 can be reduced, and thus the forward voltage of the second structure 402 can be reduced. The concentration of the additive contained in the third layer 233 is, for example, 1×10 16 cm -3 or more and 5×10 18 cm -3 or less, 1×10 16 cm -3 or more and 1×10 18 cm -3 or less, or 1×10 16 cm -3 or more and 1×10 17 cm -3 or less.

[0208] The thickness of the third layer 233 is greater than the thickness of the second layer 232. Thereby, the surface resistance of the third layer 233 can be reduced, making it easier for current to diffuse, and the output of the second structure 402 can be improved. Crystal defects can be reduced by making the second layer 232 thinner. In addition, by making the second layer 232 thinner, when the second layer 232 is formed by the MOCVD method, the thermal damage to the layer below the second layer 32 corresponding to the shortening of the film formation time can be reduced. The thickness of the second layer 232 is, for example, 100 nm or more and 2000 nm or less. The thickness of the third layer 233 is, for example, 100 nm or more and 2000 nm or less.

[0209] (The fifth nitride semiconductor layer 250 of the third structure 403)

[0210] The fourth layer 254, the fifth layer 255, and the sixth layer 256 of the fifth nitride semiconductor layer 250 of the third structure 403 will be described in detail.

[0211] The fourth layer 254 is located between the fifth layer 255 and the sixth layer 256. The fourth layer 254 contains the same additive as the first layer 31 of the first embodiment described above. By making the fourth layer 254 contain such an additive, the resistivity of the fourth layer 254 is higher than the resistivity of the fifth layer 255 and the resistivity of the sixth layer 256. Therefore, it is difficult for current to take a path from the sixth electrode 306, which is the anode of the third structure 403, to the third electrode 303, which is the cathode of the second structure 402, and the first electrode 301, which is the cathode of the first structure 401. Therefore, the leakage current flowing between the sixth electrode 306 of the third structure 403 and the third electrode 303 of the second structure 402, and the leakage current flowing between the sixth electrode 306 of the third structure 403 and the first electrode 301 of the first structure 401 can be reduced.

[0212] The concentration of the additive contained in the fourth layer 254 is higher than the concentration of the additive contained in the fifth layer 255 and the concentration of the additive contained in the sixth layer 256. The fourth layer 254 may further contain a first-conductivity-type impurity. The concentration of the additive contained in the fourth layer 254 is higher than the concentration of the first-conductivity-type impurity contained in the fourth layer 254. Thereby, the fourth layer 254 can have a higher resistance, thereby further reducing the above-mentioned leakage current.

[0213] The thickness of the fourth layer 254 is smaller than the thickness of the fifth layer 255 and the thickness of the sixth layer 256. The thickness of the fourth layer 254 is, for example, 100 nm or more and 1000 nm or less.

[0214] As described above, from the viewpoints of ease of concentration adjustment and flatness, the fourth layer 254 preferably contains C as the above-mentioned additive. The C concentration of the fourth layer 254 is higher than the C concentration of the fifth layer 255 and the C concentration of the sixth layer 256. The C concentration of the fourth layer 254 is, for example, 1×10 18 cm -3 or more and 1×10 21 cm -3 or less, preferably 1×10 19 cm -3 or more and 1×10 20 cm -3 or less.

[0215] The concentration of C contained in the fourth layer 254 is higher than the concentration of the first conductivity type impurity (e.g., Si) contained in the fourth layer 254. Thereby, the fourth layer 254 can have a higher resistance, further reducing the leakage current described above. The difference between the concentration of C contained in the fourth layer 254 and the concentration of Si contained in the fourth layer 254 is, for example, 9×10 17 cm -3 or more and 1×10 20 cm -3 or less, preferably 1×10 19 cm -3 or more and 1×10 20 cm -3 or less.

[0216] The fifth layer 255 is located between the fourth nitride semiconductor layer 240 and the fourth layer 254. The fifth layer 255 contains a first conductivity type impurity. In addition, the fifth layer 255 may contain the above-mentioned additive. The concentration of the first conductivity type impurity contained in the fifth layer 255 is higher than the concentration of the additive contained in the fifth layer 255. Thereby, the resistance of the fifth layer 255 can be reduced, thereby reducing the forward voltage of the third structure 403. The concentration of the additive contained in the fifth layer 255 is, for example, 1×10 16 cm -3 or more and 5×10 18 cm -3 or less, 1×10 16 cm -3 or more and 1×10 18 cm -3 or less, or 1×10 16 cm -3 or more and 1×10 17 cm -3 or less.

[0217] The sixth layer 256 is located between the fourth layer 254 and the third active layer 273 and contains a first conductivity type impurity. In addition, the sixth layer 256 may contain the above-mentioned additive. The concentration of the first conductivity type impurity contained in the sixth layer 256 is higher than the concentration of the additive contained in the sixth layer 256. Thereby, the resistance of the sixth layer 256 can be reduced, thereby reducing the forward voltage of the third structure 403. The concentration of the additive contained in the sixth layer 256 is, for example, 5×10 18 cm -3 or less, 1×10 18 cm -3 or less, 1×10 17 cm -3 or less.

[0218] The thickness of the sixth layer 256 is greater than the thickness of the fifth layer 255. Thus, the surface resistance of the sixth layer 256 can be reduced, making it easier for current to spread, and the output of the third structure 403 can be increased. Crystal defects can be reduced by making the fifth layer 255 thinner. In addition, by making the fifth layer 255 thinner, thermal damage to the layer below the fifth layer 255 can be reduced when the fifth layer 255 is formed by the MOCVD method. The thickness of the fifth layer 255 is, for example, 100 nm or more and 2000 nm or less. The thickness of the sixth layer 256 is, for example, 100 nm or more and 2000 nm or less.

[0219] As Figure 5A and Figure 5B shown, the third layer 233 can have a first GaN layer 233A, a second GaN layer 233B, and a first AlGaN layer 233C. The first GaN layer 233A is located between the first AlGaN layer 233C and the first layer 231. The second GaN layer 233B is farther from the first layer 231 than the first GaN layer 233A. The first AlGaN layer 233C is located between the first GaN layer 233A and the second GaN layer 233B. The Al composition ratio of the first AlGaN layer 233C is higher than the Al composition ratios of the first GaN layer 233A and the second GaN layer 233B. The resistivity of the first AlGaN layer 233C is higher than the resistivities of the first GaN layer 233A and the second GaN layer 233B. Similar to the first layer 231, such a first AlGaN layer 233C functions as a resistance layer for reducing the leakage current flowing between the fourth electrode 304 that reduces the anode of the second structure 402 and the cathodes (the first electrode 301 and the fifth electrode 305) of other structures.

[0220] In Figure 5A the example shown, the first AlGaN layer 233C has a third connection surface 230B where the third electrode 303 is disposed. The third electrode 303 contacts the first AlGaN layer 233C at the third connection surface 230B and is electrically connected to the first AlGaN layer 233C.

[0221] In Figure 5B the example shown, the first GaN layer 233A has a third connection surface 230B. The third electrode 303 contacts the first GaN layer 233A at the third connection surface 230B and is electrically connected to the first GaN layer 233A. The contact resistance between the third electrode 303 and the first GaN layer 233A can be lower than the contact resistance between the third electrode 303 and the first AlGaN layer 233C.

[0222] As Figure 6A and Figure 6BAs shown, the sixth layer 256 may have a third GaN layer 256A, a fourth GaN layer 256B, and a second AlGaN layer 256C. The third GaN layer 256A is located between the second AlGaN layer 256C and the fourth layer 254. The fourth GaN layer 256B is farther from the fourth layer 254 than the third GaN layer 256A. The second AlGaN layer 256C is located between the third GaN layer 256A and the fourth GaN layer 256B. The Al composition ratio of the second AlGaN layer 256C is higher than the Al composition ratios of the third GaN layer 256A and the fourth GaN layer 256B. The resistivity of the second AlGaN layer 256C is higher than the resistivities of the third GaN layer 256A and the fourth GaN layer 256B. Similar to the fourth layer 254, the second AlGaN layer 256C functions as a resistance layer that reduces the leakage current flowing between the sixth electrode 306 that is the anode of the third structure 403 and the cathodes (the third electrode 303 and the first electrode 301) of other structures.

[0223] In Figure 6A the example shown, the second AlGaN layer 256C has a fifth connection surface 250B disposed on the fifth electrode 305. The fifth electrode 305 contacts the second AlGaN layer 256C at the fifth connection surface 250B and is electrically connected to the second AlGaN layer 256C.

[0224] In Figure 6B the example shown, the third GaN layer 256A has a fifth connection surface 250B disposed on the fifth electrode 305. The fifth electrode 305 contacts the third GaN layer 256A at the fifth connection surface 250B and is electrically connected to the third GaN layer 256A. The contact resistance between the fifth electrode 305 and the third GaN layer 256A may be lower than the contact resistance between the fifth electrode 305 and the second AlGaN layer 256C.

[0225] The structure of Figure 6A or Figure 6B can be combined with the structure of Figure 5A Or, the structure of Figure 6A or Figure 6B can be combined with the structure of Figure 5B

[0226] The nitride semiconductor layer described can be provided between the second nitride semiconductor layer 220 and the third nitride semiconductor layer 230, and between the fourth nitride semiconductor layer 240 and the fifth nitride semiconductor layer 250 to further form a tunneling junction. Figure 1

[0227] [Light-emitting device]

[0228] Referring to Figure 7 ​​, an explanation will be given of the light-emitting device 500 of the embodiment.

[0229] The light-emitting device 500 includes: a wiring substrate 600, and one or more light-emitting elements 1 disposed on the wiring substrate 600. As the light-emitting element of the light-emitting device 500, Figure 7 In the example shown, the light-emitting element 1 of the first embodiment is shown. The light-emitting element 1 is disposed on the wiring substrate 600, and the surface on which the first electrode 71 to the fourth electrode 74 are disposed faces the wiring substrate 600. The light-emitting device 500 may include a plurality of light-emitting elements 1. At this time, the light emission of the plurality of light-emitting elements 1 can be controlled separately. The light-emitting device 500 includes, for example, 1000 or more, or 10000 or more light-emitting elements 1, and can be used for vehicle headlights and the like. In addition, the light-emitting device 500 can also be used for display devices such as displays. It should be noted that the light-emitting element of the light-emitting device 500 may also be the light-emitting element 2 of the second embodiment.

[0230] The wiring substrate 600 has an insulating substrate 601, a first wiring portion 611, and a second wiring portion 612. The insulating substrate 601 has a mounting surface 601A on which the light-emitting element 1 is disposed. The first wiring portion 611 and the second wiring portion 612 are disposed on the mounting surface 601A of the insulating substrate 601.

[0231] The third electrode 73 and the first electrode 71 of the light-emitting element 1 are electrically connected to the first wiring portion 611. The first wiring portion 611 supplies current to the third electrode 73 and the first electrode 71 to cause the first active layer 61 of the first light-emitting portion 101 to emit light. The first wiring portion 611 has a first portion 611A electrically connected to the first electrode 71 and a third portion 611B electrically connected to the third electrode 73. The third electrode 73 and the first electrode 71 are joined to the first wiring portion 611 by a joining member 700 such as solder. Alternatively, the third electrode 73 and the first electrode 71 can be directly joined to the first wiring portion 611.

[0232] The fourth electrode 74 and the second electrode 72 of the light-emitting element 1 are electrically connected to the second wiring portion 612. The second wiring portion 612 supplies current to the fourth electrode 74 and the second electrode 72 to cause the second active layer 62 of the second light-emitting portion 102 to emit light. The second wiring portion 612 has a fourth portion 612A electrically connected to the fourth electrode 74 and a second portion 612B electrically connected to the second electrode 72. The fourth electrode 74 and the second electrode 72 are joined to the second wiring portion 612 by a joining member 700 such as solder. Alternatively, the fourth electrode 74 and the second electrode 72 can be directly joined to the second wiring portion 612.

[0233] The light-emitting device 500 emits visible light formed by mixing light of a first wavelength from the first active layer 61 and light of a second wavelength from the second active layer 62. The light-emitting device 500 emits, for example, white light. The color temperature (including the correlated color temperature) of the white light is, for example, 3000K or higher and 7000K or lower.

[0234] As an example of a conventional light-emitting device that emits white light, a light-emitting device can be considered in which a wavelength conversion member containing a phosphor is disposed on a plurality of light-emitting elements so as to straddle the plurality of light-emitting elements, and white light is emitted by combining the light emitted from the light-emitting elements and the light wavelength-converted by the wavelength conversion member. The phosphor is excited by the light of the light-emitting element and emits light omnidirectionally. Therefore, when one light-emitting element emits light and other light-emitting elements adjacent to the one light-emitting element do not emit light, the light of the phosphor located on the one light-emitting element propagates to the non-light-emitting region on the other light-emitting elements, and there is a risk of a decrease in the contrast between the light-emitting region and the non-light-emitting region. Due to the decrease in the contrast between the light-emitting region and the non-light-emitting region, the outline of the image of the light generated by the light-emitting device may become blurred. In addition, the light emitted from one light-emitting element may be scattered by the phosphor located on the one light-emitting element and propagate to the non-light-emitting region on the other light-emitting elements. This can also cause a decrease in the contrast between the light-emitting region and the non-light-emitting region.

[0235] On the other hand, the light-emitting device 500 of the embodiment does not include a wavelength conversion member containing a phosphor. The light-emitting device 500 can achieve white light by combining light of a first wavelength and light of a second wavelength emitted from the light-emitting element 1. The light emitted from the light-emitting element 1 has a higher directivity than the light emitted from the wavelength conversion member containing a phosphor. Therefore, when the plurality of light-emitting elements 1 are individually controlled to emit light, the light in the light-emitting region of the driven light-emitting element 1 hardly propagates to the non-light-emitting region of the other non-driven light-emitting elements 1, and highly directional light can be emitted from the light-emitting region, thereby highlighting the contrast between the light-emitting region and the non-light-emitting region.

[0236] [Manufacturing method of light-emitting element]

[0237] Refer to Figures 8 to 13 , and the manufacturing method of the light-emitting element 1 of the first embodiment will be described.

[0238] As Figure 8As shown, the manufacturing method of the light-emitting element 1 includes: on the substrate 100, sequentially laminating a first nitride semiconductor layer 10 containing a first-conductivity-type impurity, a first active layer 61, and a second nitride semiconductor layer 20 containing a second-conductivity-type impurity to prepare a first light-emitting portion 101. For example, in a furnace capable of adjusting pressure and temperature, by using the MOCVD method, the first light-emitting portion 101 can be prepared by sequentially forming the first nitride semiconductor layer 10, the first active layer 61, and the second nitride semiconductor layer 20 on the substrate 100.

[0239] The substrate 100 is disposed in the processing chamber. Based on the MOCVD method, while heating the substrate 100, raw material gases are introduced into the processing chamber to form each layer on the substrate 100. As the substrate 100, for example, a sapphire substrate can be used.

[0240] As needed, the manufacturing method of the light-emitting element 1 includes: on the second nitride semiconductor layer 20, forming a fifth nitride semiconductor layer 50 in such a manner that the concentration of the first-conductivity-type impurity is higher than that of the first nitride semiconductor layer 10 and the third nitride semiconductor layer 30 formed through subsequent processes.

[0241] As Figure 9 shown, the manufacturing method of the light-emitting element 1 includes: forming a third nitride semiconductor layer 30 on the second nitride semiconductor layer 20. The third nitride semiconductor layer 30 is formed by, for example, the MOCVD method. While heating the substrate 100, ammonia gas is introduced into the processing chamber to form the third nitride semiconductor layer 30. The third nitride semiconductor layer 30 contains at least N (nitrogen) and Ga (gallium). Ammonia gas is the raw material gas for N. Further, trimethylgallium or triethylgallium is introduced into the processing chamber as the raw material gas for Ga to form the third nitride semiconductor layer 30.

[0242] In the process of forming the third nitride semiconductor layer 30, at least one of the heating temperature of the substrate 100 and the ammonia gas flow rate is reduced. As a result, C in the C and / or Ga source gas remaining in the processing chamber is easily introduced into the third nitride semiconductor layer 30, and the first layer 31 can be formed in the third nitride semiconductor layer 30. That is, the first layer 31 is formed on the second layer 32. In the process of forming the third nitride semiconductor layer 30, the heating temperature of the substrate 100 can be decreased by only more than 100 °C and less than 200 °C compared with the formation of the second layer 32. In addition, in the process of forming the third nitride semiconductor layer 30, the flow rate of ammonia gas can be decreased to, for example, more than 1% and less than 10% of the ammonia flow rate when forming the second layer 32. In addition, the flow rate of ammonia gas, for example, can be decreased to more than 0.1% and less than 0.5% of the ammonia flow rate when forming the first nitride semiconductor layer 10. The first layer 31 is located between the second layer 32 and the third layer 33. The C concentration of the first layer 31 is higher than the C concentration of the second layer 32 and the C concentration of the third layer 33.

[0243] The heating temperature of the substrate 100 when forming the first layer 31 is lower than the heating temperature of the substrate 100 when forming the second layer 32 and the heating temperature of the substrate 100 when forming the third layer 33. Or, the flow rate of ammonia gas when forming the first layer 31 is lower than the flow rate of ammonia gas when forming the second layer 32 and the flow rate of ammonia gas when forming the third layer 33. Or, the heating temperature and the flow rate of ammonia gas when forming the first layer 31 are lower than the heating temperature and the flow rate of ammonia gas when forming the second layer 32 and the heating temperature and the flow rate of ammonia gas when forming the third layer 33.

[0244] As Figure 10 shown, the manufacturing method of the light-emitting element 1 includes: sequentially laminating the second active layer 62 and the fourth nitride semiconductor layer 40 containing the second conductive type impurity on the third nitride semiconductor layer 30 to prepare the second light-emitting unit 102. For example, the MOCVD method can be adopted to prepare the second light-emitting unit 102 by sequentially forming the second active layer 62 and the fourth nitride semiconductor layer 40 on the third nitride semiconductor layer 30.

[0245] As Figure 11As shown, the manufacturing method of the light-emitting element 1 includes: etching the second light-emitting portion 102 and the first light-emitting portion 101 to expose the third nitride semiconductor layer 30 and the first nitride semiconductor layer 10. For example, using a resist mask, the second light-emitting portion 102 and the first light-emitting portion 101 are etched from above the fourth nitride semiconductor layer 40 by RIE (Reactive Ion Etching). By etching the second light-emitting portion 102 and the first light-emitting portion 101, a first connection surface 10B is formed on the first nitride semiconductor layer 10. By etching the second light-emitting portion 102, a second connection surface 30B and a third connection surface 30A are formed on the third nitride semiconductor layer 30.

[0246] As Figure 1 shown, the manufacturing method of the light-emitting element 1 includes: disposing the first electrode 71 to the fourth electrode 74. The first electrode 71 is disposed on the first connection surface 10B, the second electrode 72 is disposed on the second connection surface 30B, the third electrode 73 is disposed on the third connection surface 30A, and the fourth electrode 74 is disposed on the fourth connection surface 40A which is the upper surface of the fourth nitride semiconductor layer 40.

[0247] In the manufacturing method of the light-emitting element 1, the substrate 100 can be removed. In addition, in the manufacturing method of the light-emitting element 1, the first surface 10A of the first nitride semiconductor layer 10 exposed due to the removal of the substrate 100 can be roughened.

[0248] As Figure 12 shown, the formation of the third nitride semiconductor layer 30 can include: forming GaN layers (the first GaN layer 32A and the second GaN layer 32B); and forming the first AlGaN layer 32C in the middle of the GaN layers (the first GaN layer 32A and the second GaN layer 32B) before reducing at least one of the heating temperature of the substrate 100 and the flow rate of ammonia gas, in other words, before forming the above-mentioned first layer 31.

[0249] As Figure 13 shown, the formation of the third nitride semiconductor layer 30 can include: forming GaN layers (the third GaN layer 33A and the fourth GaN layer 33B); and forming the second AlGaN layer 33C in the middle of the GaN layers (the third GaN layer 33A and the fourth GaN layer 33B) after reducing at least one of the heating temperature of the substrate 100 and the flow rate of ammonia gas, in other words, after forming the above-mentioned first layer 31.

[0250] Regarding RIE under the same conditions, the etching rate of the AlGaN layer is slower than that of the GaN layer. Therefore, as Figure 12As shown, by forming the first AlGaN layer 32C in the middle of the second layer 32 of the third nitride semiconductor layer 30, using the change in the etching rate as a marker, the etching used to form the third connection surface 30A in the second layer 32 can be easily stopped at the desired depth. As Figure 2A shown, the etching can be stopped in the middle of the first AlGaN layer 32C. Alternatively, as Figure 2B shown, the etching can also be stopped after the etching passes through the first AlGaN layer 32C and reaches the first GaN layer 32A. At this time, since the material changes from AlGaN to GaN, the etching rate becomes faster. This change in the etching rate is the marker for stopping the etching.

[0251] In addition, as Figure 13 shown, by forming the second AlGaN layer 33C in the middle of the third layer 33 of the third nitride semiconductor layer 30, the etching used to form the second connection surface 30B in the third layer 33 can be easily stopped at the desired depth. As Figure 3A shown, the etching can be stopped in the middle of the second AlGaN layer 33C. Or as Figure 3B shown, the etching can also be stopped after the etching passes through the second AlGaN layer 33C and reaches the third GaN layer 33A.

[0252] Figure 4 The method for manufacturing the light-emitting element 2 of the second embodiment shown includes: in the same manner as the method for manufacturing the light-emitting element 1 of the first embodiment, forming a laminate of each layer included in the light-emitting element 2 on a substrate by, for example, the MOCVD method, and forming the first groove 901 and the second groove 902 on the laminate formed on the substrate by, for example, the RIE method.

[0253] In the same manner as the method for manufacturing the light-emitting element 1 of the first embodiment, in the process of forming the third nitride semiconductor layer 230, the first layer 231 can be formed by reducing at least one of the heating temperature of the substrate and the flow rate of ammonia; in the process of forming the fifth nitride semiconductor layer 250, the fourth layer 254 can be formed by reducing at least one of the heating temperature of the substrate and the flow rate of ammonia.

[0254] When forming the first groove 901 and the second groove 902 by the RIE method, there is a possibility that deposits adhere to the side surfaces of the first groove 901 and the second groove 902. The deposits can form a path for leakage current between the electrodes of different structures 401 to 403. The first layer 231 and the fourth layer 254 can reduce the leakage current that can flow through the deposits.

[0255] (Modification example)

[0256] Figure 14The light-emitting element 3 showing a modified example of the first embodiment. The difference between the light-emitting element 3 and the light-emitting element 1 of the first embodiment is that a third light-emitting portion 103 is provided on the second light-emitting portion 102. The third light-emitting portion has: a sixth nitride semiconductor layer 60 containing a first-conductivity-type impurity, a seventh nitride semiconductor layer 70 containing a second-conductivity-type impurity, and a third active layer 63 located between the sixth nitride semiconductor layer 60 and the seventh nitride semiconductor layer 70. In addition, from the viewpoint that the fourth electrode 74 is disposed on the fourth connection surface 60A of the sixth nitride semiconductor layer 60, the light-emitting element 3 is different from the light-emitting element 1. The third active layer 63 is a light-emitting layer that emits light and has, for example, an MQW structure. A fifth electrode 75 is formed on the fifth connection surface 60B of the sixth nitride semiconductor layer 60, and the fifth electrode 75 functions as a cathode of the third light-emitting portion 103. A sixth electrode 76 is disposed on the sixth connection surface 70A of the seventh nitride semiconductor layer 70, and the sixth electrode 76 functions as an anode of the third light-emitting portion 103.

[0257] The sixth nitride semiconductor layer 60 has a fourth layer 64, a fifth layer 65, and a sixth layer 66. The fourth layer 64 is located between the fifth layer 65 and the sixth layer 66. The fourth layer 64 contains the same additive as the first layer 31 of the first embodiment. By making the fourth layer 64 contain such an additive, the resistivity of the fourth layer 64 is higher than the resistivity of the fifth layer 65 and the resistivity of the sixth layer 66. Thereby, the leakage current flowing between the fifth electrode 75 and the fourth electrode 74 can be reduced. The concentration of the additive contained in the fourth layer 64 is higher than the concentration of the additive contained in the fifth layer 65 and the concentration of the additive contained in the sixth layer 66. The fourth layer 64 preferably contains C as the above additive. The C concentration of the fourth layer 64 can be in the same range as the C concentration of the first layer 31.

[0258] The thickness of the fourth layer 64 is smaller than the thickness of the fifth layer 65 and the thickness of the sixth layer 66. The thickness of the fourth layer 64 can be in the same range as the thickness of the first layer 31. The thickness of the fifth layer 65 can be in the same range as the thickness of the second layer 32. The thickness of the sixth layer 66 can be in the same range as the thickness of the third layer 33. The thickness of the sixth layer 66 can be greater than the thickness of the fifth layer 65.

[0259] The concentration of the first-conductivity-type impurity contained in the fourth layer 64 can be in the same range as the concentration of the first-conductivity-type impurity contained in the first layer 31. The concentration of the first-conductivity-type impurity contained in the fifth layer 65 can be in the same range as the concentration of the first-conductivity-type impurity contained in the second layer 32. The concentration of the first-conductivity-type impurity contained in the sixth layer 66 can be in the same range as the concentration of the first-conductivity-type impurity contained in the third layer 33.

[0260] The fifth layer 65 is located between the fourth nitride semiconductor layer 40 of the second light-emitting section 102 and the fourth layer 64. The sixth layer 66 is located between the fourth layer 64 and the third active layer 63.

[0261] In the light-emitting element 3 of the modified example, the first active layer 61 of the first light-emitting section 101 emits light of a first wavelength having a peak emission wavelength of 440 nm or more and 470 nm or less. The second active layer 62 of the second light-emitting section 102 emits light of a second wavelength having a peak emission wavelength of 570 nm or more and 590 nm or less. The third active layer 63 of the third light-emitting section 103 emits light of a third wavelength having a peak emission wavelength of 590 nm or more and 770 nm or less. The first wavelength, the second wavelength, and the third wavelength are all different. In the light-emitting element 3, since the first layer 31 and the fourth layer 64 reduce the leakage current between the light-emitting sections, each light-emitting section can emit light independently. The light-emitting element 3 can cause each light-emitting section to emit light independently, or can cause two or more light-emitting sections to emit light simultaneously to emit a desired color. The light-emitting element 3 can cause the first light-emitting section 101, the second light-emitting section 102, and the third light-emitting section 103 to emit light simultaneously to obtain white light.

[0262] Similar to the first embodiment, the fifth layer 65 may sequentially include a GaN layer, an AlGaN layer, and a GaN layer from the side closer to the fourth nitride semiconductor layer 40. Further, the sixth layer 66 may sequentially include a GaN layer, an AlGaN layer, and a GaN layer from the side closer to the fourth layer 64.

[0263] The light-emitting element 3 may include an eighth nitride semiconductor layer 80 located between the fourth nitride semiconductor layer 40 and the fifth layer 65. The eighth nitride semiconductor layer 80 contains a first-conductivity-type impurity and forms an interface (pn junction) with the fourth nitride semiconductor layer 40. The concentration range of the first-conductivity-type impurity contained in the eighth nitride semiconductor layer 80 is the same as that of the first-conductivity-type impurity contained in the fifth nitride semiconductor layer 50. Thereby, the width of the depletion layer formed by the pn junction between the fourth nitride semiconductor layer 40 and the eighth nitride semiconductor layer 80 can be reduced, and electrons present in the valence band of the fourth nitride semiconductor layer 40 can easily tunnel into the fifth layer 65.

[0264] (Operation of current density with respect to voltage)

[0265] In this example, the light-emitting element 1 shown in Figure 1 was fabricated by MOCVD method, and the light emission of the second light-emitting section 102 was confirmed. The proportion of In contained in the second active layer 62 of the second light-emitting section 102 was adjusted so as to emit light with the second wavelength being 570 nm or more and 590 nm or less. In this example, the third electrode 73 and the fourth electrode 74 are ordinary electrodes. Figure 15It is a graph showing the behavior of the current density of the second light-emitting portion 102 of the light-emitting element 1 with respect to voltage. From this graph, it can be seen that good characteristics can be obtained. That is, it can be seen that the power conduction between the second electrode 72 and the fourth electrode 74 is good, and the leakage between the second electrode 72 and the third electrode 73 decreases.

[0266] (SIMS analysis)

[0267] In order to study the behavior of the C concentration, a SIMS analysis was performed on a sample of a wafer having the Figure 9 shown layer structure. During the formation of the third nitride semiconductor layer 30 by MOCVD, the heating temperature of the substrate 100 and the flow rate of ammonia were reduced to form the first layer 31. That is, the second layer 32 and the first layer 31 were formed in sequence. Compared with the temperature when the second layer 32 was formed, the heating temperature of the substrate 100 when the first layer 31 was formed only decreased by 170 °C. In addition, the flow rate of ammonia decreased to 5% of the ammonia flow rate when the second layer 32 was formed. After the first layer 31 was formed to a given thickness, the heating temperature of the substrate 100 and the flow rate of ammonia were restored to the original to form the third layer 33. It should be noted that the introduction of the Si raw material was interrupted when the first layer 31 was formed. The introduction of the Si raw material was also restored to the original flow rate when the third layer 33 was formed.

[0268] Figure 16 To show the 12 C and 28 Si concentration estimated by SIMS analysis. The horizontal axis represents the depth, and the vertical axis represents the 12 C and 28 Si concentration. Hereinafter, it is simply referred to as the C concentration and the Si concentration. In Figure 16 , the dotted line represents the C concentration, and the solid line represents the Si concentration. The depth is obtained by converting the depth of the sputtering trace measured by a profilometer. Starting from the surface side, the analyzed semiconductor layers are the third layer 33, the first layer 31, and the second layer 32 in sequence. The SIMS analysis is estimated by irradiating the sample with primary ions (Cs + ). It is carried out under two conditions of the acceleration voltage of the primary ions being 2 keV and 15 keV. Figure 16 is the result of the behavior of the secondary ion intensity with respect to Si and C and the conversion of the concentration when the acceleration voltage is 15 keV. In the conversion of the concentration, a GaN layer with a known Si concentration and a GaN layer implanted with C ions were used as standard samples. Among them, for C, the result obtained by converting the concentration estimated under the condition of an acceleration voltage of 15 keV to the concentration estimated under the acceleration voltage of 2 keV was used.

[0269] From Figure 16The results can confirm that at the same moment when the Si concentration drops sharply, the C concentration rises sharply. Therefore, it can be known that by performing SIMS analysis, the first layer 31, the second layer 32, and the third layer 33 can be separated.

[0270] From the results of SIMS, it can be seen that regarding the C concentration, at least the C concentration in the first layer 31 is greater than the concentrations in the second layer 32 and the third layer 33. The C concentration in the first layer 31 is estimated to be 2.64×10 19 cm -3 . In addition, the C concentrations in the second layer 32 and the third layer 33 are estimated to be 2.18×10 18 cm -3 or so. Among them, the second layer 32 and the third layer 33 with relatively low C concentrations are affected by C from the atmosphere, so the absolute values of the concentrations are accompanied by uncertainties. It should be noted that in the measurement with an acceleration voltage of 15 keV, due to the influence of the first layer 31 with a higher C concentration, the C concentration in the second layer 32 cannot be quantitatively analyzed. However, in the measurement with an acceleration voltage of 2 keV, the secondary ion intensity of C is at the same level in the second layer 32 and the third layer 33, so it is speculated that the C concentrations are also at the same level.

[0271] The Si concentration in the third layer 33 is 1.14×10 19 cm -3 , which is smaller than 1.00×10 17 cm -3 in the first layer 31, and the Si concentration in the second layer 32 is estimated to be 1.11×10 19 cm -3 . The Si concentration in the first layer 31 is less than the background concentration.

[0272] Embodiments of the present invention may include the following light-emitting elements, light-emitting devices, and manufacturing methods of light-emitting elements.

[0273] As described above, embodiments of the present invention have been described with reference to specific examples. However, the present invention is not limited to these specific examples. Based on the above embodiments of the present invention, all modes that can be implemented by those skilled in the art through appropriate design changes as long as they include the key points of the present invention belong to the scope of the present invention. In addition, within the scope of the idea of the present invention, all various modification examples and correction examples that can be conceived by those skilled in the art also belong to the scope of the present invention.

Claims

1. A light-emitting element, comprising: a first light-emitting section having a first nitride semiconductor layer containing a first-conductivity-type impurity, a second nitride semiconductor layer containing a second-conductivity-type impurity, and a first active layer disposed between the first nitride semiconductor layer and the second nitride semiconductor layer; a second light-emitting section disposed on the second nitride semiconductor layer, the second light-emitting section having a third nitride semiconductor layer, a fourth nitride semiconductor layer containing a second-conductivity-type impurity, and a second active layer disposed between the third nitride semiconductor layer and the fourth nitride semiconductor layer; a first electrode; a second electrode; a third electrode; and a fourth electrode, Among them, wherein the third nitride semiconductor layer has: a first layer, a second layer containing a first-conductivity-type impurity and disposed between the second nitride semiconductor layer and the first layer, and a third layer containing a first-conductivity-type impurity and disposed between the first layer and the second active layer, wherein the first layer contains at least one selected from the group consisting of Be, Mg, Ca, Fe, Zn, and C, the thickness of the third layer is greater than the thickness of the second layer, the first electrode is connected to the first nitride semiconductor layer, the second electrode is connected to the third layer, the third electrode is connected to the second layer, the fourth electrode is connected to the fourth nitride semiconductor layer.

2. The light-emitting element according to claim 1, wherein the second layer has a first GaN layer, a second GaN layer, and a first AlGaN layer, the second GaN layer is closer to the first layer than the first GaN layer, the first AlGaN layer is disposed between the first GaN layer and the second GaN layer, the third electrode is connected to the first GaN layer or the first AlGaN layer.

3. The light-emitting element according to claim 1, wherein the third layer has a third GaN layer, a fourth GaN layer, and a second AlGaN layer, the fourth GaN layer is farther from the first layer than the third GaN layer, the second AlGaN layer is disposed between the third GaN layer and the fourth GaN layer, the second electrode is connected to the third GaN layer or the second AlGaN layer.

4. The light-emitting element according to any one of claims 1 to 3, wherein the thickness of the third layer is 0.5 times or more and 1.2 times or less the thickness of the first nitride semiconductor layer.

5. The light-emitting element according to any one of claims 1 to 3, wherein the emission peak wavelength of the first active layer is a first wavelength, the emission peak wavelength of the second active layer is a second wavelength different from the first wavelength.

6. The light-emitting element according to claim 5, wherein the first wavelength is 440 nm or more and 470 nm or less, the second wavelength is 570 nm or more and 590 nm or less.

7. The light-emitting element according to any one of claims 1 to 3, further comprising: A fifth nitride semiconductor layer, which is located between the second nitride semiconductor layer and the second layer, forms an interface with the second nitride semiconductor layer, and contains an impurity of a first conductivity type. The maximum value of the concentration of the impurity of the first conductivity type contained in the fifth nitride semiconductor layer is higher than the maximum value of the concentration of the impurity of the first conductivity type contained in the first nitride semiconductor layer and the maximum value of the concentration of the impurity of the first conductivity type contained in the third nitride semiconductor layer.

8. The light-emitting element according to any one of claims 1 to 3, wherein the first layer contains C, the C concentration of the first layer is higher than the C concentration of the second layer and the C concentration of the third layer.

9. The light-emitting element according to claim 8, wherein The C concentration of the first layer is 1×10 18 cm -3 or more and 1×10 21 cm -3 or less.

10. A light-emitting element, comprising: a first structure, a second structure, and a third structure, wherein the first structure has: a first stacked portion having a first nitride semiconductor layer containing an impurity of a first conductivity type, a second nitride semiconductor layer containing an impurity of a second conductivity type, a first active layer located between the first nitride semiconductor layer and the second nitride semiconductor layer, and a third nitride semiconductor layer disposed on the second nitride semiconductor layer and containing an impurity of a first conductivity type; a first electrode connected to the first nitride semiconductor layer; and a second electrode connected to the third nitride semiconductor layer, the second structure has: a second stacked portion having the first stacked portion, a fourth nitride semiconductor layer containing an impurity of a second conductivity type, a second active layer located between the third nitride semiconductor layer and the fourth nitride semiconductor layer, and a fifth nitride semiconductor layer disposed on the fourth nitride semiconductor layer and containing an impurity of a first conductivity type; a third electrode connected to the third nitride semiconductor layer; and a fourth electrode connected to the fifth nitride semiconductor layer, the third structure has: a third stacked portion having the first stacked portion, the second stacked portion, a sixth nitride semiconductor layer containing an impurity of a second conductivity type, and a third active layer located between the fifth nitride semiconductor layer and the sixth nitride semiconductor layer; a fifth electrode connected to the fifth nitride semiconductor layer; and a sixth electrode connected to the sixth nitride semiconductor layer, wherein the third nitride semiconductor layer of the second structure has: a first layer, a second layer located between the second nitride semiconductor layer and the first layer, and a third layer located between the first layer and the second active layer, wherein the first layer contains at least one selected from Be, Mg, Ca, Fe, Zn, and C, the thickness of the third layer is greater than the thickness of the second layer, the fifth nitride semiconductor layer of the third structure has: a fourth layer, a fifth layer located between the fourth nitride semiconductor layer and the fourth layer, and a sixth layer located between the fourth layer and the third active layer, Among them, the 4th layer contains at least one selected from Be, Mg, Ca, Fe, Zn, and C. The thickness of the 6th layer is greater than that of the 5th layer. The 1st stacked portion of the 1st structure is the 1st light-emitting portion. The 2nd stacked portion of the 2nd structure is the 2nd light-emitting portion. The 3rd stacked portion of the 3rd structure is the 3rd light-emitting portion.

11. The light-emitting element according to claim 10, wherein The 3rd layer has: a 1st GaN layer, a 2nd GaN layer, and a 1st AlGaN layer. Among them, the 2nd GaN layer is farther from the 1st layer than the 1st GaN layer. The 1st AlGaN layer is located between the 1st GaN layer and the 2nd GaN layer. The 3rd electrode is connected to the 1st GaN layer or the 1st AlGaN layer.

12. The light-emitting element according to claim 10 or 11, wherein The 6th layer has: a 3rd GaN layer, a 4th GaN layer, and a 2nd AlGaN layer. Among them, the 4th GaN layer is farther from the 4th layer than the 3rd GaN layer. The 2nd AlGaN layer is located between the 3rd GaN layer and the 4th GaN layer. The 5th electrode is connected to the 3rd GaN layer or the 2nd AlGaN layer.

13. A light-emitting device that does not include a wavelength conversion member containing a phosphor, the light-emitting device includes: A wiring substrate having a 1st wiring portion that supplies current between the 3rd electrode and the 1st electrode, and a 2nd wiring portion that supplies current between the 4th electrode and the 2nd electrode; and One or more light-emitting elements according to any one of claims 1 to 3, which are arranged on the wiring substrate.

14. A light-emitting device that emits visible light formed by mixing light of the following 1st wavelength and light of the following 2nd wavelength, the light-emitting device includes: A wiring substrate having a 1st wiring portion that supplies current between the 3rd electrode and the 1st electrode, and a 2nd wiring portion that supplies current between the 4th electrode and the 2nd electrode; and One or more light-emitting elements according to any one of claims 1 to 3, which are arranged on the wiring substrate. Among them, The emission peak wavelength of the 1st active layer is the 1st wavelength. The emission peak wavelength of the 2nd active layer is the 2nd wavelength different from the 1st wavelength.

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