Light emitter

Abstract

To provide a light emitter capable of improving light extraction efficiency.SOLUTION: A light emitter includes a semiconductor structure having a p-side semiconductor layer, an active layer disposed on the p-side semiconductor layer, an n-side semiconductor layer including a first layer that is disposed on the active layer and has a first surface located on the opposite side to the active layer, and a second layer disposed on a part of the first surface, an n-side electrode that is disposed on the second layer and electrically connected to the second layer, a p-side electrode electrically connected to the p-side semiconductor layer, a first insulating film disposed between the first surface on which the second layer is not disposed in a sectional view and the n-side electrode, and a second insulating film covering the semiconductor structure. The band gap energy of the second layer is smaller than the band gap energy of the first layer, and the refractive index difference between the second insulating film and the first layer is smaller than the refractive index difference between the first insulating film and the first layer.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a light-emitting device. [Background technology]

[0002] Patent Document 1 discloses a light emitting device in which an n-type GaAs contact layer and a transparent dielectric reflector are disposed on an n-type AlGaInP cladding layer. The light emitting device of Patent Document 1 has room for improvement in light extraction efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-278112 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a light-emitting element capable of improving the light extraction efficiency. [Means for solving the problem]

[0005] According to one aspect of the present invention, a light-emitting element includes a semiconductor structure having a p-side semiconductor layer, an active layer arranged on the p-side semiconductor layer, an n-side semiconductor layer including a first layer arranged on the active layer and having a first surface located opposite the active layer, and a second layer arranged on a part of the first surface, an n-side electrode arranged on the second layer and electrically connected to the second layer, a p-side electrode electrically connected to the p-side semiconductor layer, a first insulating film arranged between the first surface on which the second layer is not arranged and the n-side electrode in a cross-sectional view, and a second insulating film covering the semiconductor structure, wherein the band gap energy of the second layer is smaller than the band gap energy of the first layer, and the refractive index difference between the second insulating film and the first layer is smaller than the refractive index difference between the first insulating film and the first layer.

[0006] According to one aspect of the present invention, a light-emitting element includes a semiconductor structure having a p-side semiconductor layer, an active layer arranged on the p-side semiconductor layer, an n-side semiconductor layer including a first layer arranged on the active layer and having a first surface located opposite the active layer, and a second layer arranged on a part of the first surface, an n-side electrode arranged on the second layer and electrically connected to the second layer, a p-side electrode electrically connected to the p-side semiconductor layer, a first insulating film arranged between the first surface on which the second layer is not arranged and the n-side electrode in a cross-sectional view, and a second insulating film covering the semiconductor structure, wherein a band gap energy of the second layer is smaller than a band gap energy of the first layer, and a thickness of the second insulating film is smaller than a thickness of the first insulating film. Effect of the Invention

[0007] According to the present invention, it is possible to provide a light emitting element capable of improving the light extraction efficiency. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic plan view of the light-emitting element according to the first embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 11 is a schematic plan view of a light-emitting element according to a second embodiment. [Figure 4] FIG. 13 is a schematic plan view of a light-emitting element according to a third embodiment. [Diagram 5] FIG. 13 is a schematic plan view of a light-emitting element according to a fourth embodiment. [Figure 6] FIG. 13 is a schematic plan view of a light-emitting element according to a fifth embodiment. [Figure 7] FIG. 13 is a schematic cross-sectional view of a portion of a light-emitting element according to a sixth embodiment. [Figure 8] FIG. 13 is a schematic cross-sectional view of a portion of a light-emitting element according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the light-emitting device of the embodiment will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiment are not intended to be limited thereto, and are merely illustrative examples, unless otherwise specified. The sizes and positional relationships of the components shown in each drawing may be exaggerated to clarify the explanation. In the following explanation, the same names and symbols indicate the same or similar components, and detailed explanations will be omitted as appropriate. In addition, as a cross-sectional view, an end view showing only a cut surface may be shown.

[0010] In the following description, terms indicating a specific direction or position (e.g., "upper", "lower", and other terms including these terms) may be used. However, these terms are merely used for the purpose of making the relative direction or position in the referenced drawings easier to understand. As long as the relationship of the relative direction or position by terms such as "upper" and "lower" in the referenced drawings is the same, the arrangement in drawings other than the present disclosure, in actual products, etc., may not be the same as that in the referenced drawings. In this specification, the positional relationship expressed as "upper (or lower)" includes, for example, when two members are assumed to exist, a case in which the two members are in contact with each other, and a case in which the two members are not in contact with each other and one member is located above (or below) the other member. In addition, unless otherwise specified, a member covering a covered object includes a case in which the member is in contact with the covered object and directly covers the covered object, and a case in which the member indirectly covers the covered object without contacting the covered object.

[0011] In the figures shown below, directions may be indicated by the X-axis, Y-axis, and Z-axis. The X-axis, Y-axis, and Z-axis are mutually perpendicular. For example, in this specification, the direction along the X-axis is the first direction X, the direction along the Y-axis is the second direction Y, and the direction along the Z-axis is the third direction Z.

[0012] [First embodiment] The light-emitting element 1 of the first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. Note that the second insulating film 22 is not shown in Fig. 1 in order to make it easier to see the configuration covered with the second insulating film 22 in a plan view.

[0013] The light emitting element 1 of the first embodiment includes a semiconductor structure 10, an n-side electrode 31, a p-side electrode 32, a first insulating film 21, and a second insulating film 22.

[0014] <Semiconductor structure> The semiconductor structure 10 has a p-side semiconductor layer 17, an active layer 15 arranged on the p-side semiconductor layer 17 in the third direction Z, and an n-side semiconductor layer 16 arranged on the active layer 15 in the third direction Z. The third direction Z corresponds to the stacking direction of the p-side semiconductor layer 17, the active layer 15, and the n-side semiconductor layer 16. The size of one side of the semiconductor structure 10 in a plan view is, for example, not less than 50 μm and not more than 1000 μm.

[0015] The active layer 15 is a light-emitting layer that emits light, and may have, for example, a MQW (Multiple Quantum Well) structure including a plurality of barrier layers and a plurality of well layers. The active layer 15 emits light having an emission peak wavelength of, for example, 590 nm or more and 780 nm or less. The active layer 15 is, for example, Al x Ga y In 1-x-y P (x≧0, y≧0, x+y≦1). The n-side semiconductor layer 16 has a semiconductor layer containing an n-type impurity. The p-side semiconductor layer 17 has a semiconductor layer containing a p-type impurity.

[0016] The n-side semiconductor layer 16 includes a first layer 11 and a second layer 12. The first layer 11 is disposed on the active layer 15 in the third direction Z, and has a first surface 11a located on the opposite side of the active layer 15. The second layer 12 is disposed on a part of the first surface 11a. The first surface 11a has a portion where the second layer 12 and a first insulating film 21 described later are disposed, and a portion exposed from the second layer 12 and the first insulating film 21. In the first surface 11a, the area of ​​the portion exposed from the second layer 12 and the first insulating film 21 is larger than the area of ​​the portion where the second layer 12 and the first insulating film 21 are disposed. The band gap energy of the second layer 12 is smaller than the band gap energy of the first layer 11. In other words, the absorptance of the second layer 12 for the light emitted by the active layer 15 is higher than the absorptance of the first layer 11 for the light emitted by the active layer 15. For example, the first layer 11 is made of Al. x Ga y In 1-x-y The first layer 11 and the second layer 12 include a layer of GaAs (x≧0, y≧0, x+y≦1), and the second layer 12 includes a layer of GaAs. The first layer 11 and the second layer 12 include n-type impurities. The n-type impurity concentration of the first layer 11 is higher than the n-type impurity concentration of the second layer 12.

[0017] As described later, the second layer 12 functions as an n-side contact layer that reduces the resistance of the electrical connection between the n-side electrode 31 and the n-side semiconductor layer 16. The thickness of the first layer 11 is greater than the thickness of the second layer 12. The thickness of the first layer 11 is, for example, 1 μm or more and 5 μm or less. The thickness of the second layer 12 is, for example, 0.05 μm or more and 1 μm or less. The first layer 11 has a function of diffusing a current in the surface direction of the n-side semiconductor layer 16. The thickness of each layer of the semiconductor structure 10 represents the maximum thickness in the third direction Z.

[0018] The p-side semiconductor layer 17 includes a third layer 13 and a fourth layer 14. In the third direction Z, the fourth layer 14 is disposed on the third layer 13, and the active layer 15 is disposed on the fourth layer 14. The third layer 13 and the fourth layer 14 contain p-type impurities. The p-type impurity concentration of the third layer 13 is higher than that of the fourth layer 14. The third layer 13 functions as a p-side contact layer that reduces the resistance of the electrical connection between the p-side conductive layer 35 and the p-side semiconductor layer 17 described later. By disposing the third layer 13, the forward voltage can be reduced as compared with the case where the p-side conductive layer 35 is connected to the fourth layer 14. In addition, by providing the third layer 13, it is possible to facilitate the diffusion of current in the plane direction. For example, the third layer 13 includes a layer of GaP. The fourth layer 14 is, for example, a layer having a function of promoting the recombination of electrons and holes in the active layer 15 and a function of reducing the diffusion of p-type impurities into the active layer 15. For example, the fourth layer 14 includes a layer of AlInP or a layer of AlGaInP.

[0019] <n-side electrode> The n-side electrode 31 is disposed on the second layer 12 of the n-side semiconductor layer 16, is in contact with the second layer 12, and is electrically connected to the second layer 12. As described above, the first layer 11 is Al x Ga y In 1-x-y a layer of P, and the second layer 12 includes a layer of GaAs. The contact resistance between a GaAs-based material and a metal is generally lower than the contact resistance between an AlGaInP-based material and a metal. Therefore, by the n-side electrode 31 being in contact with the second layer 12, the contact resistance between the n-side electrode 31 and the n-side semiconductor layer 16 can be reduced as compared with the case where the n-side electrode 31 is in contact with the first layer 11.

[0020] As the material of the n-side electrode 31, for example, Au, Ge, Ni, Ti, Pt, etc. can be used.

[0021] The light emitted by the active layer 15 is extracted to the outside of the semiconductor structure 10 mainly from the first surface 11a exposed from the n-side electrode 31 in a plan view. The light emitted by the active layer 15 is also extracted to the outside of the semiconductor structure 10 from the side surfaces of the semiconductor structure 10. The side surfaces of the semiconductor structure 10 include the side surfaces of the n-side semiconductor layer 16, the side surfaces of the active layer 15, and the side surfaces of the p-side semiconductor layer 17.

[0022] <First insulating film> 2, the second layer 12 is disposed on a portion of the first surface 11a. In a cross-sectional view, the first insulating film 21 is disposed between the n-side electrode 31 and another portion of the first surface 11a on which the second layer 12 is not disposed. Between the n-side electrode 31 and the first surface 11a, the second layer 12 in contact with the portion of the first surface 11a and the first insulating film 21 in contact with the other portion of the first surface 11a are disposed.

[0023] The first insulating film 21 may be, for example, a silicon oxide film or a silicon nitride film.

[0024] In the region where the first insulating film 21 is disposed between the n-side electrode 31 and the first surface 11a, the absorption of light emitted by the active layer 15 in the second layer 12, which has a smaller band gap energy than the first layer 11, can be reduced. Furthermore, the light emitted by the active layer 15 can be totally reflected at the interface between the first insulating film 21 and the first surface 11a, reducing the light absorption in the n-side electrode 31, and can be further totally reflected at the interface between the p-side semiconductor layer 17 and a third insulating film 23 (described later) disposed below the p-side semiconductor layer 17, for example, and directed toward the side surface or the first surface 11a of the semiconductor structure 10. This can improve the light extraction efficiency of the light-emitting element 1.

[0025] The portion of the first surface 11a exposed from the second layer 12 and the first insulating film 21 can be a rough surface including a plurality of convex portions. This can improve the light extraction efficiency of the light emitting element 1. The arithmetic mean roughness of the portion of the first surface 11a exposed from the second layer 12 and the first insulating film 21 can be, for example, 0.01 μm or more and 0.5 μm or less. The surface roughness of the portion of the first surface 11a in contact with the first insulating film 21 is preferably smaller than the surface roughness of the portion of the first surface 11a exposed from the second layer 12 and the first insulating film 21. This can facilitate total reflection of the light emitted by the active layer 15 at the interface between the first insulating film 21 and the first surface 11a.

[0026] <Second insulating film> The second insulating film 22 covers the semiconductor structure 10 and protects the semiconductor structure 10 from moisture and the like. The second insulating film 22 covers the side surface and the first face 11a of the semiconductor structure 10. The surface of the second insulating film 22 opposite to the surface on the semiconductor structure 10 side is, for example, an interface with air or a resin layer covering the light-emitting element 1.

[0027] The second insulating film 22 can cover the second layer 12 and the n-side electrode 31. At least a part of the upper surface of the n-side electrode 31 is exposed from the second insulating film 22. A bonding member such as a wire can be bonded to the portion of the upper surface of the n-side electrode 31 that is exposed from the second insulating film 22.

[0028] The second insulating film 22 is transparent to light emitted by the active layer 15. The light emitted by the active layer 15 is extracted to the outside of the semiconductor structure 10 through the second insulating film 22 from the side surfaces and the first face 11a of the semiconductor structure 10.

[0029] The refractive index difference between the second insulating film 22 and the first layer 11 is smaller than the refractive index difference between the first insulating film 21 and the first layer 11. Or, the thickness of the second insulating film 22 is smaller than the thickness of the first insulating film 21. Or, the refractive index difference between the second insulating film 22 and the first layer 11 is smaller than the refractive index difference between the first insulating film 21 and the first layer 11, and the thickness of the second insulating film 22 may be smaller than the thickness of the first insulating film 21. The thicknesses of the first insulating film 21 and the second insulating film 22 represent the maximum thickness in the third direction Z on the first surface 11a.

[0030] By making the refractive index difference between the second insulating film 22 and the first layer 11 smaller than the refractive index difference between the first insulating film 21 and the first layer 11, it is possible to make it easier for total reflection to occur at the interface between the first insulating film 21 and the first surface 11a, while making it difficult for total reflection to occur at the interface between the second insulating film 22 and the first surface 11a. This makes it possible to improve the extraction efficiency of light extracted from the first surface 11a through the second insulating film 22, while reducing the absorption of light at the n-side electrode 31. The refractive index of the second insulating film 22 can be, for example, 1.45 or more and 1.9 or less. The refractive index of the first insulating film 21 can be, for example, in the range of 1.45 or more and 1.9 or less, and can be 0.02 or more and 0.45 or less smaller than that of the second insulating film 22. The refractive index of the first layer 11 can be, for example, 2.5 or more and 4 or less. The refractive index of the second layer 12 is, for example, 3.2 or more and 3.6 or less.

[0031] As described above, when the first surface 11a has a rough surface including a plurality of protrusions, it is preferable that a plurality of protrusions are formed on the upper surface of the second insulating film 22 covering the rough surface. This reduces the reflection of light at the interface between the second insulating film 22 and the air, and improves the efficiency of extracting light from the second insulating film 22.

[0032] By making the thickness of the second insulating film 22 thinner than the thickness of the first insulating film 21, light absorption in the second insulating film 22 can be reduced, and the light extraction efficiency of the light extracted from the second insulating film 22 to the outside of the semiconductor structure 10 can be improved. The thickness of the second insulating film 22 can be, for example, 110% or more and 400% or less of the thickness of the first insulating film 21. For example, the thickness of the first insulating film 21 can be 250 nm or more and 400 nm or less. For example, the thickness of the second insulating film 22 can be 100 nm or more and less than 250 nm.

[0033] As the second insulating film 22, for example, a silicon oxide film or a silicon nitride film can be used.

[0034] <p-side electrode> The p-side electrode 32 is electrically connected to the p-side semiconductor layer 17. The p-side electrode 32 can be electrically connected to the p-side semiconductor layer 17, for example, via a p-side conductive layer 35 described later. As the material of the p-side electrode 32, for example, Au, Ge, Ni, Ti, Pt, etc. can be used.

[0035] Also, as shown in FIG. 1, the n-side electrode 31 can have a pad portion 31A and an extension portion 31B extending from the pad portion 31A. In the example shown in FIG. 1, two extension portions 31B extend from the pad portion 31A. The extension portion 31B may be one or three or more. The first insulating film 21 can have a first portion 21A disposed at a position overlapping the pad portion 31A and a second portion 21B disposed at a position overlapping the extension portion 31B in a plan view.

[0036] The second layer 12 is located under the pad portion 31A and the extension portion 31B. In the example shown in FIG. 1, in a plan view, the outer edge 31a of the n-side electrode 31 is located inside the outer edge 12a of the second layer 12. Also, in a plan view, the outer edge 21a of the first insulating film 21 is located inside the outer edge 31a of the n-side electrode 31 and the outer edge 12a of the second layer 12.

[0037] The pad portion 31A is electrically connected to an external circuit via a bonding member such as a wire. The extension portion 31B and the second layer 12 arranged below the extension portion 31B facilitate the diffusion of current in the planar direction of the first layer 11.

[0038] 1, the area of ​​the pad portion 31A is larger than the area of ​​the extension portion 31B. In this case, by disposing the first portion 21A of the first insulating film 21 at a position overlapping with the pad portion 31A in a plan view, it is easy to reduce light absorption in the pad portion 31A and improve the light extraction efficiency.

[0039] By arranging the second portion 21B of the first insulating film 21 at a position overlapping with the extension portion 31B in a planar view, the current can be diffused by the extension portion 31B while reducing the absorption of light in the extension portion 31B, thereby improving the light extraction efficiency.

[0040] The light emitting element 1 may further include a third insulating film 23, a p-side conductive layer 35, and a substrate 50.

[0041] The substrate 50 supports the p-side conductive layer 35, the third insulating film 23, and the semiconductor structure 10. As the substrate 50, for example, a silicon substrate or an aluminum nitride substrate can be used.

[0042] The third insulating film 23 is disposed on the p-side conductive layer 35, and the semiconductor structure 10 is disposed on the third insulating film 23. The third insulating film 23 contacts the surface of the p-side semiconductor layer 17 opposite to the active layer 15. Light from the active layer 15 toward the third insulating film 23, and light reflected at the interface between the first insulating film 21 and the first surface 11a toward the third insulating film 23 can be reflected toward the side surface or the first surface 11a of the semiconductor structure 10 at the interface between the third insulating film 23 and the p-side semiconductor layer 17. This can improve the light extraction efficiency of the light emitting element 1. For example, a silicon oxide film or a silicon nitride film can be used as the third insulating film 23. The thickness of the third insulating film 23 is preferably thicker than the thickness of the second insulating film 22. This can efficiently reflect the light toward the third insulating film 23 at the interface between the third insulating film 23 and the p-side semiconductor layer 17. For example, the thickness of the third insulating film 23 is 110% or more and 500% or less of the thickness of the second insulating film 22. For example, the thickness of the third insulating film 23 can be set to be not less than 250 nm and not more than 500 nm.

[0043] The third insulating film 23 has a plurality of holes 23a. The holes 23a penetrate the third insulating film 23 in the third direction Z.

[0044] The p-side conductive layer 35 is disposed on the substrate 50. The p-side electrode 32 is electrically connected to the p-side semiconductor layer 17 via the p-side conductive layer 35. The p-side conductive layer 35 has a plurality of p-side connection parts 35a located in the holes 23a of the third insulating film 23. The p-side connection parts 35a contact the p-side semiconductor layer 17 in the holes 23a of the third insulating film 23. The p-side conductive layer 35 has a p-side electrode arrangement part 35b disposed at a position not overlapping with the semiconductor structure 10 in a plan view. The p-side electrode 32 is disposed on the p-side electrode arrangement part 35b.

[0045] The p-side conductive layer 35 can have a first p-side conductive layer 33 and a second p-side conductive layer 34. The first p-side conductive layer 33 is disposed on the substrate 50. The first p-side conductive layer 33 can be made of a material having a lower electrical resistivity than the second p-side conductive layer 34. This can reduce the forward voltage of the light-emitting element 1. The first p-side conductive layer 33 can be made of a metal such as gold or platinum. The p-side electrode 32 is in contact with the upper surface of the first p-side conductive layer 33 exposed from the second p-side conductive layer 34 in the p-side electrode arrangement portion 35b.

[0046] The second p-side conductive layer 34 is disposed between the first p-side conductive layer 33 and the p-side semiconductor layer 17 at the p-side connection portion 35a. The second p-side conductive layer 34 contacts the p-side semiconductor layer 17. The second p-side conductive layer 34 can reduce the diffusion of metal contained in the first p-side conductive layer 33 into the p-side semiconductor layer 17. By using a material having a lower electrical resistivity for the first p-side conductive layer 33 than the second p-side conductive layer 34, the forward voltage rise of the light-emitting element 1 can be reduced. Examples of materials that can be used for the second p-side conductive layer 34 include ITO (Indium Tin Oxide) and ZnO (Zinc Oxide).

[0047] The second insulating film 22 can cover the p-side conductive layer 35 and the p-side electrode 32. At least a part of the upper surface of the p-side electrode 32 is exposed from the second insulating film 22. A bonding member such as a wire can be bonded to the portion of the upper surface of the p-side electrode 32 that is exposed from the second insulating film 22.

[0048] Hereinafter, the other embodiments will be described mainly with respect to configurations different from the first embodiment with reference to Figures 3 to 8. In the plan views of Figures 3 to 6, the second insulating film 22 is not shown, similar to Figure 1.

[0049] [Second embodiment] In the light-emitting element 1 of the first embodiment, the second portion 21B of the first insulating film 21 is continuous along the extension direction of the extension portion 31B of the n-side electrode 31. In contrast, according to the light-emitting element 2 of the second embodiment, as shown in FIG. 3, the second portions 21B of the first insulating film 21 are arranged apart from each other along the extension direction of the extension portion 31B of the n-side electrode 31. In this embodiment, the second layer 12 has a plurality of through holes, and the second portions 21B of the first insulating film 21 are arranged in each of the plurality of through holes. In a plan view, the plurality of second portions 21B are covered by the extension portion 31B of the n-side electrode 31. In a plan view, the second layer 12 is arranged on the first surface 11a of the first layer 11 located between the plurality of second portions 21B.

[0050] According to the second embodiment, the contact area between the second layer 12 and the n-side electrode 31 and the contact area between the second layer 12 and the first surface 11a are increased, thereby reducing the forward voltage, compared to the first embodiment. Also, the light absorption in the extension portion 31B is reduced, thereby improving the light extraction efficiency.

[0051] [Third embodiment] As shown in Fig. 4, according to the light-emitting element 3 of the third embodiment, similarly to the second embodiment, the multiple second portions 21B of the first insulating film 21 are arranged at a distance from each other along the extension direction of the extension portion 31B of the n-side electrode 31. Note that in Fig. 4, the first insulating film 21 is shown shaded. In addition to the portion of the first insulating film 21 exposed from the n-side electrode 31, the portion overlapping under the n-side electrode 31 is also shaded. In plan view, the second layer 12 is arranged on the first surface 11a of the first layer 11 located between the multiple second portions 21B.

[0052] Furthermore, according to the light emitting device 3 of the third embodiment, the width of the second portion 21B of the first insulating film 21 in the direction perpendicular to the extension direction of the extension portion 31B of the n-side electrode 31 is larger than the width of the extension portion 31B in the direction perpendicular to the extension direction of the extension portion 31B. As a result, compared to the second embodiment, the area where the first surface 11a contacts the first insulating film 21 can be increased, and the light extraction efficiency can be easily improved by reflection at the interface between the first surface 11a and the first insulating film 21. In addition, in this embodiment, the width of the second portion 21B of the first insulating film 21 in the direction perpendicular to the extension direction of the extension portion 31B is the same as the width of the second layer 12 in the direction perpendicular to the extension direction of the extension portion 31B. As shown in FIG. 4, the upper surface of the second portion 21B of the first insulating film 21 is exposed from the extension portion 31B.

[0053] [Fourth embodiment] 5, the contact area between the second portion 21B of the first insulating film 21 and the first layer 11 decreases with increasing distance from the pad portion 31A. As a result, the contact area between the n-side electrode 31 and the second layer 12 increases toward the tip side in the extension direction of the extension portion 31B, making it difficult for current to concentrate near the pad portion 31A and increasing the current density in an area away from the pad portion 31A, thereby reducing the variation in current density distribution in the n-side semiconductor layer 16.

[0054] In the fourth embodiment, the second portion 21B of the first insulating film 21 continues along the extension direction of the extension portion 31B of the n-side electrode 31, and the width of the second portion 21B in a direction perpendicular to the extension direction of the extension portion 31B decreases with increasing distance from the pad portion 31A. On the other hand, the width of the second layer 12 in a direction perpendicular to the extension direction of the extension portion 31B is constant. As a result, the contact area between the n-side electrode 31 and the second layer 12 increases toward the tip side of the extension portion 31B.

[0055] [Fifth embodiment] In the light-emitting element 5 of the fifth embodiment shown in Fig. 6, similarly to the fourth embodiment, the contact area between the second portion 21B of the first insulating film 21 and the first layer 11 decreases with increasing distance from the pad portion 31A. This can reduce the variation in the current density distribution in the n-side semiconductor layer 16. In Fig. 6, similarly to Fig. 4, the first insulating film 21 is shown shaded.

[0056] In the fifth embodiment, the second portions 21B of the first insulating film 21 are disposed apart from one another along the extension direction of the extension portion 31B, and the width of the second portions 21B in the extension direction of the extension portion 31B decreases with increasing distance from the pad portion 31A. As a result, the contact area between the n-side electrode 31 and the second layer 12 increases toward the tip side of the extension portion 31B.

[0057] [Sixth embodiment] Fig. 7 is an enlarged cross-sectional view of a portion of the light-emitting device 6 of the sixth embodiment. The cross section shown in Fig. 7 is the same as the cross section taken along line VII-VII in Fig. 1, and corresponds to the cross section of the portion where the extension portion 31B of the n-side electrode 31 is disposed. The cross-sectional structure shown in Fig. 7 is also applicable to the portion where the pad portion 31A of the n-side electrode 31 is disposed.

[0058] According to the sixth embodiment, the thickness of the first insulating film 21 is greater than the thickness of the second layer 12. This makes it possible to increase the reflectance of the first insulating film 21 with respect to light from the active layer 15, while reducing light absorption in the second layer 12. For example, the thickness of the first insulating film 21 is 110% or more and 300% or less of the thickness of the second layer 12.

[0059] Furthermore, a part of the first insulating film 21 is disposed on the second layer 12. As a result, the first insulating film 21 is disposed in contact with the n-side semiconductor layer 16 on the first surface 11a of the first layer 11 and the second layer 12, and the contact area between the first insulating film 21 and the n-side semiconductor layer 16 can be increased compared to the case where the first insulating film 21 is in contact with the n-side semiconductor layer 16 only on the first surface 11a. As a result, the first insulating film 21 is less likely to peel off from the n-side semiconductor layer 16.

[0060] The n-side electrode 31 covers the upper surface of the first insulating film 21, the side surface of the first insulating film 21, and a part of the upper surface of the second layer 12 continuing from the side surface of the first insulating film 21. A part of the first insulating film 21 is disposed on the second layer 12, and the n-side electrode 31 covers a part of the upper surface of the second layer 12 continuing from the side surface of the first insulating film 21 located on the second layer 12. This allows the n-side electrode 31 to be in contact with a part of the upper surface of the second layer 12 even when the n-side electrode 31 is disposed in contact with a part of the upper surface of the second layer 12 and the first insulating film 21 is continuous in the extension direction of the extension portion 31B.

[0061] [Seventh embodiment] Fig. 8 is an enlarged cross-sectional view of a portion of the light-emitting element 7 of the seventh embodiment. The cross section shown in Fig. 8 corresponds to the cross section of the same portion as in Fig. 7. Note that the cross-sectional structure shown in Fig. 8 is also applicable to the portion where the pad portion 31A of the n-side electrode 31 is arranged.

[0062] According to the seventh embodiment, the first insulating film 21 is in contact with the n-side semiconductor layer 16 only on the first surface 11a of the first layer 11, and is not in contact with the second layer 12. A gap is disposed between the second layer 12 and the first insulating film 21 on the first surface 11a, and the n-side electrode 31 is in contact with the first surface 11a in the gap. With this arrangement, light from the active layer 15 that propagates through the first insulating film 21 can be more easily reflected at the interface between the first insulating film 21 and the n-side electrode 31 than when the first insulating film 21 is in contact with the second layer 12, and light absorption in the second layer 12 can be reduced.

[0063] Moreover, since the thickness of the first insulating film 21 is greater than the thickness of the second layer 12, it is possible to reduce light absorption in the second layer 12 while increasing the reflectance of the first insulating film 21 to the light from the active layer 15. Note that, in the first to fifth embodiments, the thickness of the first insulating film 21 may be greater than the thickness of the second layer 12.

[0064] Embodiments of the present invention may include the following light emitting devices.

[0065] [Section 1] a semiconductor structure including a p-side semiconductor layer, an active layer disposed on the p-side semiconductor layer, an n-side semiconductor layer including a first layer disposed on the active layer and having a first surface located opposite the active layer, and a second layer disposed on a portion of the first surface; an n-side electrode disposed on the second layer and electrically connected to the second layer; a p-side electrode electrically connected to the p-side semiconductor layer; a first insulating film disposed between the first surface, on which the second layer is not disposed, and the n-side electrode in a cross-sectional view; A second insulating film covering the semiconductor structure; Equipped with the band gap energy of the second layer is smaller than the band gap energy of the first layer; a refractive index difference between the second insulating film and the first layer is smaller than a refractive index difference between the first insulating film and the first layer. [Section 2] a semiconductor structure including a p-side semiconductor layer, an active layer disposed on the p-side semiconductor layer, an n-side semiconductor layer including a first layer disposed on the active layer and having a first surface located opposite the active layer, and a second layer disposed on a portion of the first surface; an n-side electrode disposed on the second layer and electrically connected to the second layer; a p-side electrode electrically connected to the p-side semiconductor layer; a first insulating film disposed between the first surface, on which the second layer is not disposed, and the n-side electrode in a cross-sectional view; A second insulating film covering the semiconductor structure; Equipped with the band gap energy of the second layer is smaller than the band gap energy of the first layer; The light emitting element, wherein the second insulating film is thinner than the first insulating film. [Section 3] 3. The light emitting device according to item 1 or 2, wherein the first insulating film has a thickness greater than a thickness of the second layer. [Section 4] the n-side electrode has a pad portion and an extension portion extending from the pad portion, The light-emitting element according to any one of items 1 to 3, wherein the first insulating film has, in a planar view, a first portion arranged at a position overlapping the pad portion and a second portion arranged at a position overlapping the extension portion. [Section 5] The second portions are arranged apart from each other along the extension direction of the extension portion, 5. The light-emitting device according to item 4, wherein the second layer is disposed on the first surface located between the plurality of second portions in a plan view. [Section 6] Item 6. The light-emitting element according to item 5, wherein a width of the second portion in a direction perpendicular to the extension direction is larger than a width of the extension portion in the direction perpendicular to the extension direction. [Section 7] 7. The light emitting device according to any one of items 4 to 6, wherein a contact area between the second portion and the first layer decreases with increasing distance from the pad portion. [Section 8] 8. The light emitting device according to any one of items 1 to 7, wherein a part of the first insulating film is disposed on the second layer. [Section 9] Item 9. The light-emitting element according to item 8, wherein the n-side electrode covers an upper surface of the first insulating film, a side surface of the first insulating film, and a part of an upper surface of the second layer that is continuous with the side surface of the first insulating film.

[0066] The above describes the embodiments of the present invention with reference to specific examples. However, the present invention is not limited to these specific examples. All forms that can be implemented by a person skilled in the art through appropriate design modifications based on the above-described embodiments of the present invention also belong to the scope of the present invention as long as they include the gist of the present invention. In addition, within the scope of the concept of the present invention, a person skilled in the art may come up with various modified examples and examples of modifications, and these modified examples and examples of modifications also belong to the scope of the present invention. [Explanation of symbols]

[0067] Reference Signs List 1 to 7: light-emitting element, 10: semiconductor structure, 11: first layer, 11a: first surface, 12: second layer, 13: third layer, 14: fourth layer, 15: active layer, 16: n-side semiconductor layer, 17: p-side semiconductor layer, 21: first insulating film, 21A: first portion, 21B: second portion, 22: second insulating film, 23: third insulating film, 31: n-side electrode, 31A: pad portion, 31B: extension portion, 32: p-side electrode, 33: first p-side conductive layer, 34: second p-side conductive layer, 35: p-side conductive layer, 50: substrate

Claims

1. a semiconductor structure including a p-side semiconductor layer, an active layer disposed on the p-side semiconductor layer, an n-side semiconductor layer including a first layer disposed on the active layer and having a first surface located opposite the active layer, and a second layer disposed on a portion of the first surface; an n-side electrode disposed on the second layer and electrically connected to the second layer; a p-side electrode electrically connected to the p-side semiconductor layer; a first insulating film disposed between the first surface, on which the second layer is not disposed, and the n-side electrode in a cross-sectional view; A second insulating film covering the semiconductor structure; Equipped with the band gap energy of the second layer is smaller than the band gap energy of the first layer; A light-emitting element, wherein a refractive index difference between the second insulating film and the first layer is smaller than a refractive index difference between the first insulating film and the first layer.

2. a semiconductor structure including a p-side semiconductor layer, an active layer disposed on the p-side semiconductor layer, an n-side semiconductor layer including a first layer disposed on the active layer and having a first surface located opposite the active layer, and a second layer disposed on a portion of the first surface; an n-side electrode disposed on the second layer and electrically connected to the second layer; a p-side electrode electrically connected to the p-side semiconductor layer; a first insulating film disposed between the first surface, on which the second layer is not disposed, and the n-side electrode in a cross-sectional view; A second insulating film covering the semiconductor structure; Equipped with the band gap energy of the second layer is smaller than the band gap energy of the first layer; A light emitting element, wherein the second insulating film is thinner than the first insulating film.

3. The light-emitting element according to claim 1 , wherein the first insulating film is thicker than the second layer.

4. the n-side electrode has a pad portion and an extension portion extending from the pad portion, The light-emitting element according to claim 1 , wherein the first insulating film has, in a plan view, a first portion arranged at a position overlapping the pad portion and a second portion arranged at a position overlapping the extension portion.

5. The second portions are arranged apart from each other along the extension direction of the extension portion, The light-emitting element according to claim 4 , wherein the second layer is disposed on the first surface located between the plurality of second portions in a plan view.

6. The light-emitting element according to claim 5 , wherein a width of the second portion in a direction perpendicular to the extension direction is larger than a width of the extension portion in the direction perpendicular to the extension direction.

7. The light-emitting element according to claim 4 , wherein a contact area between the second portion and the first layer decreases with increasing distance from the pad portion.

8. The light-emitting element according to claim 1 , wherein a portion of the first insulating film is disposed on the second layer.

9. The light-emitting element according to claim 8 , wherein the n-side electrode covers an upper surface of the first insulating film, a side surface of the first insulating film, and a part of an upper surface of the second layer that is continuous with the side surface of the first insulating film.

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