Light-emitting element and light-emitting device

Abstract

Provided are a light-emitting element and a light-emitting device having improved light output and lifetime. A light-emitting element (1), which uses a group III nitride semiconductor containing Al and has an emission wavelength of 200 nm to 280 nm, is provided with: a substrate (10); a semiconductor layer in which an n-type layer (11), a light-emitting layer (12), and a p-type layer (14) are laminated in this order on the substrate (10); a hole (23) provided in a predetermined region on the surface of the p-type layer (14) and having a depth reaching the n-type layer (11); a p-side electrode (15) which is provided on the p-type layer (14) so as to be in contact with the p-type layer (14), and which has a reflectance of 50% or more for ultraviolet light having an emission wavelength; and an n-side electrode (16) provided on or above the n-type layer (11) exposed on the bottom surface of the hole (23). The hole (23) and the n-side electrode (16) have a pattern of a plurality of dots arranged two-dimensionally, and the area of the p-side electrode (15) is 0.75 mm2 or more.

Description

Technical Field

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

[0002] It is known that there is a sterilization device that sterilizes bacteria and viruses in running water by irradiating ultraviolet light. Mercury lamps are widely used as light sources. Mercury lamps use mercury, so there are problems such as strong toxicity and heavy environmental burden. In addition, if mercury lamps are used, there is also a problem that the size of the sterilization device becomes larger.

[0003] On the other hand, the wavelength of ultraviolet light of the light-emitting element using the III-nitride semiconductor corresponds to the band of about 210nm to 400nm. It is well known that UVC (wavelength 100nm to 280nm) can efficiently sterilize and disinfect, and its use in sterilization and disinfection of water, air, etc. has attracted attention. Therefore, the operation of replacing mercury lamps by using light-emitting elements of the III-nitride semiconductor with a light emission wavelength of UVC is being promoted.

[0004] Patent Documents 1 and 2 disclose a structure in which, in a light-emitting element using a Group III nitride semiconductor, an n-side electrode has a pattern of a plurality of dots arranged two-dimensionally.

[0005] Patent Document 1: Japanese Patent Application No. 2017-513234

[0006] Patent Document 2: International Publication No. 2010 / 146808

[0007] However, the light output and life of the existing UVC light emitting elements do not reach the performance required to replace the mercury lamp. In addition, the light output of the light emitting device in which the UVC light emitting element is mounted on a base also needs to be improved. Summary of the invention

[0008] The present disclosure is made in view of the above background. First, a light emitting element having improved light output and life is provided. Second, a light emitting device having improved light output is provided in which a light emitting element is mounted on a base.

[0009] One method disclosed herein is a light-emitting element, which uses a Group III nitride semiconductor containing Al and has a light-emitting wavelength of 200 nm to 280 nm, and comprises: a substrate; a semiconductor layer, which is formed by stacking an n-type layer, a light-emitting layer, and a p-type layer in order from the substrate side on the substrate; a hole, which is provided in a predetermined area on the surface of the p-type layer and has a depth reaching the n-type layer; a p-side electrode, which is provided on the p-type layer in contact with the p-type layer and has a reflectivity of ultraviolet light of the light-emitting wavelength of 50% or more; and an n-side electrode, which is provided on or above the n-type layer exposed at the bottom surface of the hole, the hole and the n-side electrode having a pattern of a plurality of points arranged in two dimensions, and the area of ​​the p-side electrode is 0.75 mm 2 above.

[0010] In addition, another embodiment of the present invention is a light-emitting device, comprising: a light-emitting element of the above-mentioned embodiment; and a base, on which the above-mentioned is mounted inverted, and a reflective layer is provided on the surface on which the light-emitting element is mounted, wherein the reflectivity of the reflective layer for ultraviolet light of the emission wavelength of the above-mentioned light-emitting element is greater than 50%, and in a plan view of the above-mentioned reflective layer, the above-mentioned reflective layer is provided in an area which is at least 0 μm or more and less than 500 μm outwardly from the side end face of the above-mentioned light-emitting element.

[0011] In addition, another embodiment of the present invention is a light-emitting device comprising: a light-emitting element, which uses a Group III nitride semiconductor containing Al and has a light-emitting wavelength of 200nm to 280nm; and a base, on which the light-emitting element is mounted inverted, and has a reflective layer arranged on the surface of the side on which the light-emitting element is mounted and a surface electrode layer bonded to the light-emitting element, and the base is formed in a flat plate shape, the reflective layer has an insulating layer as the bottom layer, and in a plan view of the surface electrode layer, a part of the surface electrode layer is arranged on the outside of the side end face of the light-emitting element, the reflectivity of the reflective layer for ultraviolet light of the light-emitting wavelength of the light-emitting element is greater than 50%, and in a plan view, the reflective layer is arranged in a region that is at least 0μm or more and less than 500μm deviated outward from the side end face of the light-emitting element.

[0012] In the above-described light-emitting element, the n-side electrode has a pattern of a plurality of dots arranged two-dimensionally. Therefore, the area of ​​the p-side electrode can be increased. Furthermore, the area of ​​the p-side electrode is set to 0.75 mm 2 In addition, in the above-described light emitting device, when the reflective layer is viewed from above, the reflective layer is provided in a region which is at least 0 μm or more and 500 μm or less outward from the side end face of the light emitting element. Therefore, the light output can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional view showing the structure of the light emitting element according to the first embodiment, and is a cross-sectional view taken in a direction perpendicular to the principal surface of the substrate.

[0014] Figure 2 It is a diagram showing the plan view shape of the electrode of the light emitting element according to the first embodiment.

[0015] Figure 3 It is a graph showing the relationship between the area of ​​the p-side electrode and the light output.

[0016] Figure 4 It is a graph showing the relationship between the area of ​​the p-side electrode and the lifespan.

[0017] Figure 5 It is a cross-sectional view showing the structure of a light emitting element according to a modification of the first embodiment, and is a cross-sectional view in a direction perpendicular to the principal surface of the substrate.

[0018] Figure 6 It is a diagram showing the plan view shape of an electrode of a light emitting element according to a modification of the first embodiment.

[0019] Figure 7 It is a diagram showing the plan view shape of an electrode of a light emitting element according to a modification of the first embodiment.

[0020] Figure 8 It is a diagram showing the plan view shape of an electrode of a light emitting element according to a modification of the first embodiment.

[0021] Fig. 9 It is a cross-sectional view showing the structure of the light emitting device according to the second embodiment, and is a cross-sectional view perpendicular to the main surface of the base.

[0022] Fig.10 This is a plan view of the base from above.

[0023] Fig.11 It is a cross-sectional view showing the structure of the first reflective layer, and is a cross-sectional view perpendicular to the main surface of the base.

[0024] Fig.12 This is a graph showing the radiation intensity on the susceptor surface.

[0025] Description of Reference Numerals

[0026] 1, 2, 100...light emitting element; 3...light emitting device; 10...substrate; 11...n-type layer; 12...light emitting layer; 13...electron blocking layer; 14...p-type layer; 15...p-side electrode; 16...n-side electrode; 17A, 17B...intermediate electrode; 18...protective film; 19A...p-side wiring electrode; 19B...n-side wiring electrode; 20...p-side pad electrode; 21...n-side pad electrode; 101...base; 102...substrate layer; 103...surface electrode layer; 104...back electrode layer; 105...first reflective layer; 105A...first insulating layer; 105B...metal reflective layer; 105C...second insulating layer; 106...second reflective layer. DETAILED DESCRIPTION

[0027] The light-emitting element uses a Group III nitride semiconductor containing Al and has a light emission wavelength of 200nm to 280nm. In addition, it has: a substrate; a semiconductor layer, which is formed by stacking an n-type layer, a light-emitting layer, and a p-type layer in sequence on the substrate; a hole, which is provided in a predetermined area on the surface of the p-type layer and has a depth reaching the n-type layer; a p-side electrode, which is provided on the p-type layer in contact with the p-type layer and has a reflectivity of ultraviolet light of the light emission wavelength of 50% or more; and an n-side electrode, which is provided on or above the n-type layer exposed at the bottom surface of the hole. In addition, the hole and the n-side electrode have a pattern of multiple points arranged in two dimensions. The area of ​​the p-side electrode is 0.75mm 2 above.

[0028] In the above light emitting element, the diameter of the dots of the n-side electrode may be 5 μm to 100 μm, and the center-to-center distance between adjacent dots may be 50 μm to 200 μm. This can sufficiently increase the area of ​​the p-side electrode and improve the in-plane diffusibility of the current.

[0029] In the above-mentioned light-emitting element, the ratio of the area of ​​the p-side electrode to the total area of ​​the hole and the area of ​​the p-type layer in a plan view may be 70% or more. The reflection of ultraviolet light formed by the p-side electrode can be increased, thereby improving the light extraction efficiency.

[0030] In the above light emitting element, the overall thickness of the light emitting element may be greater than or equal to 0.5 mm and less than or equal to 1 mm. This can improve light output and life.

[0031] Alternatively, the light emitting element may include: a p-side pad electrode disposed on or above the p-side electrode and an n-side pad electrode disposed on or above the n-side electrode, wherein the total area of ​​the p-side pad electrode and the area of ​​the n-side pad electrode is 0.7 mm 2As described above, the contact area between the light emitting element and the mounting substrate is increased, thereby improving heat dissipation. As a result, the life span can be improved.

[0032] In the above-mentioned light-emitting element, the area of ​​the p-side electrode, the diameter of the n-side electrode dots, and the center-to-center distance of adjacent dots may be set so that the light output becomes 150 mW or more and the life becomes 10,000 hours or more when driven at 350 mA.

[0033] Alternatively, the light-emitting device comprises: the light-emitting element mentioned above; and a base, on which the light-emitting element is mounted inverted, and has a reflective layer arranged on the surface on the side on which the light-emitting element is mounted, the reflectivity of the reflective layer to ultraviolet light of the emission wavelength of the light-emitting element is greater than 50%, and in a plan view, the reflective layer is arranged in a local area that is at least 0 μm or more and less than 500 μm outward from the side end face of the light-emitting element.

[0034] In the above light emitting device, the reflective layer may be provided in all regions extending outward by 0 μm or more from the side end surface of the light emitting element in a plan view.

[0035] Alternatively, in the above-mentioned light-emitting device, the base has a surface electrode layer bonded to the light-emitting element, the reflective layer has an insulating layer as the bottom layer, and when looking down at the surface electrode layer, a part of the surface electrode layer is arranged outside the side end surface of the light-emitting element.

[0036] Alternatively, in the above-mentioned light emitting device, the reflective layer includes: an insulating layer; and a metal reflective layer, which is provided on or above the insulating layer and is composed of a metal having a reflectivity of 50% or more for ultraviolet light of a wavelength emitted by the light emitting element.

[0037] In the above-mentioned light emitting device, the reflective layer may include a DBR reflective layer having a reflectivity of 90% or more with respect to ultraviolet light having a wavelength of light emitted by the light emitting element.

[0038] Alternatively, in the above-mentioned light-emitting device, the reflective layer includes: an insulating layer; a metal reflective layer, which is arranged on or above the insulating layer and is composed of a metal having a reflectivity of 50% or more for ultraviolet light of the emission wavelength of the light-emitting element; and a DBR layer, which is arranged on or above the metal reflective layer and has a reflectivity of 50% or more for ultraviolet light of the emission wavelength of the light-emitting element.

[0039] In the above light-emitting device, a thickness of a substrate of the light-emitting element may be 900 μm or more.

[0040] The light-emitting device comprises: a light-emitting element, which uses a III-group nitride semiconductor containing Al and has a light-emitting wavelength of 200nm to 280nm; and a base, on which the light-emitting element is mounted inverted, and has a reflective layer arranged on the surface of the side on which the light-emitting element is mounted and a surface electrode layer bonded to the light-emitting element, and the above-mentioned base is formed in a flat plate shape, the reflective layer has an insulating layer as the lowermost layer, when the surface electrode layer is viewed from above, a part of the surface electrode layer is arranged on the outside of the side end face of the light-emitting element, the reflectivity of the reflective layer for ultraviolet light of the light-emitting wavelength of the light-emitting element is 50% or more, and in a plan view, the reflective layer is arranged in a region that is at least 0μm or more and 500μm or less deviated outward from the side end face of the light-emitting element.

[0041] (First embodiment)

[0042] Figure 1 1 is a cross-sectional view showing the structure of the light emitting element according to the first embodiment, and is a cross-sectional view in a direction perpendicular to the main surface of the substrate 10. Figure 2 The figure shows the plan view shape of the electrode of the light emitting element of the first embodiment. The light emitting element of the first embodiment is a flip-chip type and emits ultraviolet light. The light emission wavelength of the light emitting element 1 is UVC, for example, 200nm to 280nm.

[0043] 1. Structure of Light Emitting Element 1

[0044] like Figure 1 As shown, the light emitting element 1 of the first embodiment includes a substrate 10, an n-type layer 11, a light emitting layer 12, an electron blocking layer 13, a p-type layer 14, a p-side electrode 15, an n-side electrode 16, intermediate electrodes 17A, 17B, a protective film 18, a p-side wiring electrode 19A, an n-side wiring electrode 19B, a p-side pad electrode 20, and an n-side pad electrode 21. Hereinafter, each element will be described. Hereinafter, the stack of the n-type layer 11, the light emitting layer 12, the electron blocking layer 13, and the p-type layer 14 is sometimes referred to as a semiconductor layer.

[0045] The substrate 10 is a substrate made of sapphire with the c-plane as the main surface. For the substrate 10, any material other than sapphire can be used as long as it has a high transmittance for the emission wavelength and can grow a group III nitride semiconductor. The thickness of the substrate 10 is preferably 0.5 mm to 1 mm. It can improve the light extraction efficiency.

[0046] Alternatively, an anti-reflection film may be provided on the back side of the substrate 10. The back side of the substrate 10 corresponds to the surface on the side opposite to the n-type layer 11 side and corresponds to the light output side. By providing the anti-reflection film, the ultraviolet light is prevented from being reflected on the back side of the substrate 10 and returning to the element side, thereby improving the light extraction efficiency. The anti-reflection film is composed of SiO2 with a thickness of, for example, 1 / 4 of the emission wavelength.

[0047] The n-type layer 11 is located on the substrate 10 via a buffer layer (not shown). The n-type layer 11 is composed of n-AlGaN. The n-type impurity is composed of Si, and the Si concentration is 5×10 18 / cm 3 ~5×10 19 / cm 3 The n-type layer 11 may be composed of a plurality of layers.

[0048] The light-emitting layer 12 is located on the n-type layer 11. The light-emitting layer 12 has an MQW structure in which well layers and barrier layers are alternately and repeatedly stacked. The number of repetitions is, for example, 2 to 5. The well layer is composed of AlGaN, and its Al composition is set according to the desired emission wavelength. The barrier layer is composed of AlGaN with a larger Al composition than the well layer. The barrier layer can also be AlGaInN with a larger band gap energy than the well layer. In addition, the light-emitting layer 12 can also have an SQW structure.

[0049] The electron blocking layer 13 is located on the light emitting layer 12. The electron blocking layer 13 is composed of p-AlGaN having a higher Al composition than the barrier layer of the light emitting layer 12. The electron blocking layer 13 prevents electrons injected from the n-side electrode 16 from diffusing to the p-type layer 14 side beyond the light emitting layer 12.

[0050] The p-type layer 14 is located on the electron blocking layer 13. The p-type layer 14 is composed of p-AlGaN. In the light emitting element 1 of the first embodiment, all semiconductor layers from the n-type layer 11 to the p-type layer 14 are composed of AlGaN. This suppresses the absorption of ultraviolet light by the semiconductor layer. The Al composition of the p-type layer 14 is, for example, 5% to 80%. The p-type impurity is composed of Mg. The Mg concentration is 1×10 19 / cm 3 The above. Alternatively, the p-type layer 14 may be composed of a plurality of layers having different Al compositions and Mg concentrations. In this case, the layer in contact with the p-side electrode 15 may be composed of p-AlGaN having an Al composition of 5% to 80%. In addition, the p-type layer 14 is not limited to being composed of AlGaN, and may be a III-group nitride semiconductor containing Al, or may be composed of AlGaInN.

[0051] The uppermost layer of the p-type layer 14 composed of multiple layers may be composed of a thin GaN layer having a thickness of 1 molecular layer or more and 50 nm or less. The uppermost layer of the p-type layer 14 constitutes a contact layer with the p-side electrode 15 .

[0052] A hole 23 having a depth reaching the n-type layer 11 is formed locally on the surface of the p-type layer 14. The hole 23 has a pattern of a plurality of dots, and the plurality of holes 23 are arranged in a lattice shape (see Figure 2). The n-type layer 11 is exposed at the bottom of the hole 23. The hole 23 for exposing the n-type layer 11 has a pattern of multiple dots, thereby ensuring the uniformity of light emission within the surface. In addition, the hole 23 has a pattern of multiple dots, so that the reduction of the light emitting area (the area of ​​the p-type layer 14) caused by the hole 23 is minimized, and the area of ​​the p-side electrode 15 is expanded, thereby achieving an increase in light output.

[0053] The plan view shape of each hole 23 is circular. In addition, each hole 23 can also be formed into a polygon such as a square or a regular hexagon. In the case of a regular hexagon, it is preferred to use the side of the hole 23 as the m-plane. The arrangement pattern of the holes 23 is a regular triangular lattice. In addition, the arrangement pattern of the holes 23 can also be a two-dimensional arrangement pattern such as a square lattice or a honeycomb. Preferably, it is a regular triangular lattice or a square lattice.

[0054] The diameter of the hole 23 is preferably 5 μm to 100 μm. In addition, the center-to-center distance between adjacent holes 23 is preferably 50 μm to 200 μm. By setting the diameter and spacing of the hole 23 in this way, not only can the area of ​​the p-side electrode 15 be sufficiently ensured, but also the in-plane diffusibility of the current can be improved. Here, the diameter of the hole 23 is the diameter of the circumscribed circle of the hole 23.

[0055] The p-side electrode 15 is provided on the p-type layer 14 so as to be in contact with the p-type layer. The p-side electrode 15 is provided in the region where the hole 23 is not provided on the surface of the p-type layer 14 and in the region other than the vicinity of the edge of the p-type layer 14 (see Figure 2 ). As a result, the light emitting area becomes larger. The p-side electrode 15 is a reflective electrode for improving the light extraction efficiency by reflecting the ultraviolet light radiated from the light emitting layer 12 toward the substrate 10. The p-side electrode 15 is composed of a material having a reflectivity of 50% or more for ultraviolet light of the emission wavelength. For example, it is composed of an alloy mainly composed of Ru, Rh, Ru, and Rh, ITO / Al, etc. Ru and Rh have a higher reflectivity in UVC, and the contact resistance relative to the p-type layer 14 composed of p-AlGaN is also low. Therefore, they are preferably the p-side electrode 15 of the light emitting element 1 of UVC. A more preferred reflectivity is 70% or more.

[0056] The area of ​​the p-side electrode 15 is 0.75 mm 2 The element area, the diameter of the hole 23, and the arrangement pattern are set to satisfy this condition. As a result, the light output and life of the light emitting element 1 of the first embodiment can be improved. The light output is improved because the reflection area formed by the p-side electrode 15 is increased. The life is improved because the current density is reduced by increasing the area of ​​the p-side electrode 15.

[0057] In particular, by making the area of ​​the p-side electrode 15 0.75 mm 2As described above, the light emitting element 1 of the first embodiment can provide sufficient performance to replace the mercury lamp. In order to replace the mercury lamp with the light emitting element 1, a light output of 150 mW when driven at 350 mA and a life of 10,000 hours when driven at 350 mA are required. By making the area of ​​the p-side electrode 15 0.75 mm 2 The above can achieve this condition.

[0058] The p-side electrode 15 preferably has an area of ​​8 mm 2 This is because if the area of ​​the p-side electrode 15 is too large, the probability that the semiconductor layer includes crystal defects increases, resulting in a decrease in production yield.

[0059] In addition, it is preferred that the area of ​​the p-side electrode 15 is 70% or more compared to the element area (the total value of the area of ​​the p-type layer 14 and the area of ​​the hole 23). The reflection of ultraviolet light formed by the p-side electrode 15 can be increased, and the light extraction efficiency can be improved. In addition, it is preferred that the area of ​​the p-side electrode 15 is 95% or less of the element area. This is to ensure that the area of ​​the hole 23 is sufficient and the in-plane diffusibility of the current is not impaired.

[0060] The n-side electrode 16 is provided on or above the n-type layer 11 exposed at the bottom surface of each hole 23. Therefore, the n-side electrode 16 also has a pattern of a plurality of dots (see Figure 2 ).

[0061] The plan view shape of the dots of the n-side electrode 16 has a shape obtained by reducing the plan view shape of the hole 23. If the plan view shape of the hole 23 is a circle, the plan view shape of the n-side electrode 16 is a circle with a smaller diameter than the hole 23. The arrangement pattern of the dots of the n-side electrode 16 is also the same as the arrangement pattern of the hole 23. In this way, the n-side electrode 16 has a pattern of dots arranged two-dimensionally, so that the area where the p-side electrode 15 is provided can be expanded, and the in-plane diffusibility of the current can be improved.

[0062] The n-side electrode 16 is composed of a structure formed by heat-treating V / Al / Ti. In addition, Ti / Al / Ti and the like can be used for the n-side electrode 16. Specifically, the structure formed by heat-treating V / Al / Ti has AlN x The structure of a layer composed of, a layer composed of a metal mainly composed of Al and containing V and Ti, and a layer composed of Ti.

[0063] AlN x The thickness of the layer is 1 nm to 3 nm. x is, for example, 0.4 to 0.7. Alternatively, x may decrease as the distance from the n-type layer 11 in the thickness direction increases. In this case, the average value of x in the thickness direction is 0.4 to 0.7. In addition, there is also a case where Ga diffuses from the n-type layer 11. In this case, the AlN xThe layer composed of Al has a higher Al composition than the n-type layer 11. y Ga 1-y N x (0.4≤x≤0.7). If the Al composition of the n-type layer 11 is a, then a<y≤1 exists. y is, for example, greater than 0.7. In addition, in this case, x may decrease as the distance from the n-type layer 11 in the thickness direction is increased, or y may increase as the distance from the n-type layer 11 in the thickness direction is increased.

[0064] The layer composed of a metal mainly composed of Al and containing V and Ti has a thickness of 50 nm to 500 nm. The ratio of Al, V and Ti is, for example, 50 mol% to 85 mol% for Al, 5 mol% to 20 mol% for V and 10 mol% to 30 mol% for Ti.

[0065] In the n-side electrode 16 having the above structure, the contact resistance with respect to the n-type layer 11 is reduced. For example, the contact resistance of the n-side electrode 16 with respect to the n-type layer 11 is 4×10 -4 Ω·cm 2 The following is considered to be the reason that, first, AlN x The structured layer functions as a good contact layer for the n-type layer 11. In addition, secondly, it is considered that nitrogen vacancies are generated on the surface of the n-type layer 11, and the n-type layer 11 is converted, so that the contact resistance is reduced.

[0066] The layer composed of Ti is provided as a cover for suppressing evaporation of Al in the n-side electrode 16 during alloying. In addition to Ti, TiN, Ni, Pt, Au, etc. can also be used.

[0067] The intermediate electrodes 17A and 17B are provided on the p-side electrode 15 and the n-side electrode 16, respectively. The plan view shape of the intermediate electrode 17A is the same as the plan view shape of the p-side electrode 15. The plan view shape of the intermediate electrode 17B is the same as the plan view shape of the n-side electrode 16, and has a pattern of a plurality of dots. The intermediate electrodes 17A and 17B are composed of, for example, Ti / Ni / Au / Al.

[0068] Alternatively, the intermediate electrodes 17A and 17B may be omitted, and the p-side wiring electrode 19A may be directly connected to the p-side electrode 15 , and the n-side wiring electrode 19B may be directly connected to the n-side electrode 16 .

[0069] The protective film 18 is provided to cover the entire upper surface of the element. That is, the protective film 18 is continuously provided on the side and surface of the p-side electrode 15 and the n-side electrode 16, the surface and side of the semiconductor layer, the side of the element separation groove, and the inside of the hole 23. In addition, the protective film 18 has a structure in which the first protective film 18A and the second protective film 18B are stacked in order from the semiconductor layer side.

[0070] The protective film 18 is made of an insulator, for example, SiO2. In addition, SiN, Al2O3, TiO2, AlN, etc. can also be used. It can also be a stack of multiple materials. In addition, the materials of the first protective film 18A and the second protective film 18B can also be changed.

[0071] The p-side wiring electrode 19A and the n-side wiring electrode 19B are provided between the first protection film 18A and the second protection film 18B. The p-side wiring electrode 19A is connected to the intermediate electrode 17A via a hole formed in the first protection film 18A, and is connected to the p-side pad electrode 20 via a hole formed in the second protection film 18B. In addition, the n-side wiring electrode 19B is connected to each intermediate electrode 17B via a hole formed in the first protection film 18A, and is connected to the n-side pad electrode 21 via a hole formed in the second protection film 18B. The p-side wiring electrode 19A and the n-side wiring electrode 19B are composed of, for example, Ti / Ni / Au / Al.

[0072] By disposing the p-side wiring electrode 19A and the n-side wiring electrode 19B between the intermediate electrodes 17A and 17B and the p-side pad electrode 20 and the n-side pad electrode 21, the shapes of the p-side pad electrode 20 and the n-side pad electrode 21 can be freely set. In addition, the hole 23 can be arranged on the entire surface, so that the in-plane uniformity of light emission can be improved.

[0073] The p-side pad electrode 20 and the n-side pad electrode 21 are provided on and apart from the protective film 18. The p-side pad electrode 20 is connected to the p-side wiring electrode 19A via a hole formed in the second protective film 18B. In addition, the n-side pad electrode 21 is connected to the n-side wiring electrode 19B via a hole formed in the second protective film 18B. The p-side pad electrode 20 and the n-side pad electrode 21 are made of, for example, Ti / Pt / Au / AuSn.

[0074] like Figure 2 As shown, the p-side pad electrode 20 and the n-side pad electrode 21 are arranged in a small rectangular shape slightly inside the outer rectangular shape of the light emitting element 1. The p-side pad electrode 20 and the n-side pad electrode 21 have a region obtained by dividing the small rectangular shape. The p-side pad electrode 20 and the n-side pad electrode 21 have a shape divided into two equal parts by a band-shaped boundary region along a straight line parallel to one side of the small rectangular shape. Figure 2 In the embodiment, the band-shaped boundary region has a shape extending in the up-down direction at the center in the left-right direction.

[0075] The total area of ​​the p-side pad electrode 20 and the area of ​​the n-side pad electrode 21 is preferably 0.7 mm 2The above. The contact area between the light emitting element 1 of the first embodiment and the mounting substrate is enlarged, which can improve the heat dissipation. As a result, the life span can be improved. In addition, for the same reason, the ratio of the area of ​​the p-side pad electrode 20 and the area of ​​the n-side pad electrode 21 to the total value of the light emitting area (the area of ​​the p-side electrode 15) is preferably 70% or more.

[0076] The overall thickness of the light emitting element 1 of the first embodiment (the distance from the back surface of the substrate 10 to the surfaces of the p-side pad electrode 20 and the n-side pad electrode 21 ) is preferably 0.5 mm to 1 mm. Within this range, light output and life can be improved.

[0077] According to the above, in the light emitting element 1 of the first embodiment, the n-side electrode 16 has a pattern of a plurality of dots arranged two-dimensionally. Thus, the area of ​​the n-side electrode 16 is reduced and the area of ​​the p-side electrode 15 is increased without impairing the in-plane diffusion of the current. In addition, the area of ​​the p-side electrode 15 is 0.75 mm 2 As a result, the light output and life of the light emitting element 1 can be improved. In particular, a light output of 150 mW when driven at 350 mA and a life of 10,000 hours when driven at 350 mA, which are required performances as a replacement for a mercury lamp, can be achieved. Here, the life is the time until the light output becomes 70% of the initial driving level.

[0078] 2. Experimental results

[0079] Next, experimental results related to the light emitting element 1 of the first embodiment will be described.

[0080] For the light emitting element 1 of the first embodiment, the light emitting element 1 was produced with the area of ​​the p-side electrode 15 changed to various values, and the light output and life when driven at 350 mA were measured. The area of ​​the p-side electrode 15 was changed according to the outer shape of the p-side electrode 15, the hole 23, and the diameter of the n-side electrode 16. In addition, the life is the time until the light output becomes 70% of the initial driving when driven at 350 mA.

[0081] Figure 3 1 is a graph showing the relationship between the area of ​​the p-side electrode 15 and the light output. The vertical axis of the graph represents the value when the light output is 150 mW and normalized to 1. Figure 3 As shown in FIG. 1 , it can be seen that the larger the area of ​​the p-side electrode 15 is, the greater the light output is. The light output required to replace the mercury lamp is 150 mW when driven at 350 mA. Figure 3 It can be seen that if the area of ​​the p-side electrode 15 is 0.5 mm 2 The above can achieve this condition.

[0082] also, Figure 4is a graph showing the relationship between the area of ​​the p-side electrode 15 and the lifetime. Figure 4 As shown in FIG. 1 , it can be seen that the lifetime increases linearly with the increase in the area of ​​the p-side electrode 15. The lifetime required to replace the mercury lamp is 10,000 hours when driven at 350 mA. Figure 4 It can be seen that the life exceeds 10,000 hours when the area of ​​the p-side electrode 15 is 0.75 mm 2 The above situation.

[0083] like Figure 3 and Figure 4 As shown in FIG. 1 , it can be seen that in order to satisfy the light output and life required for replacing the mercury lamp, the area of ​​the p-side electrode 15 is set to 0.75 mm 2 That’s all.

[0084] (Variation of the first embodiment)

[0085] Figure 5 1 is a cross-sectional view showing the structure of the light emitting element 2 according to a modification of the first embodiment, and is a cross-sectional view in a direction perpendicular to the main surface of the substrate. Figure 5 As shown in FIG. 1 , the light emitting element 2 of the modified embodiment omits the p-side wiring electrode 19A and the n-side wiring electrode 19B from the light emitting element 1 of the first embodiment. Compared with the light emitting element 1 of the first embodiment, the light emitting element 2 changes the plan view shape of the p-side electrode 15, the n-side electrode 16, the p-side pad electrode 20, and the n-side pad electrode 21. The light emitting element 2 has a structure in which the intermediate electrode 17A is connected to the p-side pad electrode 20, and the intermediate electrode 17B is connected to the n-side pad electrode 21.

[0086] If the p-side wiring electrode 19A and the n-side wiring electrode 19B are omitted, restrictions are imposed on the shapes of the n-side electrode 16 , the p-side pad electrode 20 , and the n-side pad electrode 21 , but the structure of the light emitting element 2 can be simplified.

[0087] Figure 6 to Figure 8 It is shown Figure 5 FIG. 2 is a diagram showing various electrode shapes of the light emitting element 2 in a modified form. Figure 6 to Figure 8 The electrode shape is described below.

[0088] Figure 6 The electrode shapes shown are as follows. In a plan view, the p-side pad electrode 20 and the n-side pad electrode 21 are arranged in a small rectangular shape slightly inside the outer rectangular shape of the light emitting element 2. The p-side pad electrode 20 and the n-side pad electrode 21 have regions formed by unequally dividing the small rectangular shape. The p-side pad electrode 20 and the n-side pad electrode 21 are divided into two by a linear boundary region along the end edge near the end edge of the light emitting element 2. Figure 6In the figure, the linear boundary region has a shape extending in the up-down direction on the right side in the left-right direction. The one with the smaller area is the p-side pad electrode 20, and the one with the larger area is the n-side pad electrode 21. The n-side pad electrode 21 is formed into a wide rectangle, and the p-side pad electrode 20 is formed into a long and narrow rectangle.

[0089] The holes 23 and the n-side electrode 16 have circular dot shapes and are arranged in an equilateral triangular lattice in the region corresponding to the lower portion of the n-side pad electrode 21. The holes 23 and the n-side electrode 16 are not arranged in the region corresponding to the lower portion of the p-side pad electrode 20 and the lower portion of the linear region.

[0090] In a plan view, holes 24 for connecting the p-side electrode 15 and the p-side pad electrode 20 are included in the p-side pad electrode 20. The holes 24 have a circular dot shape and are arranged in a straight line along the edge of the light emitting element 2 at predetermined intervals.

[0091] Figure 7 The electrode shapes shown are as follows. Figure 7 The electrode shape shown is consistent with Figure 6 Examples of different electrode shapes shown. In the plan view, the p-side pad electrode 20 and the n-side pad electrode 21 are arranged in a small rectangular shape that is slightly inside the outer rectangular shape of the light-emitting element 2. The p-side pad electrode 20 and the n-side pad electrode 21 have an area formed by dividing the small rectangular shape unequally. The p-side pad electrode 20 and the n-side pad electrode 21 are, relative to the small rectangular shape, divided into two by a boundary area along a straight line at a 45° angle relative to the side of the rectangle at its corner. The one that is a right-angled isosceles triangle is the p-side pad electrode 20, and the other (a pentagon with the corner of the rectangle cut off) is the n-side pad electrode 21.

[0092] and Figure 6 Similarly, the holes 23 and the n-side electrode 16 have circular dot shapes and are arranged in an equilateral triangular lattice in the region corresponding to the lower portion of the n-side pad electrode 21. The holes 23 and the n-side electrode 16 are not arranged in the region corresponding to the lower portion of the p-side pad electrode 20 and the lower portion of the linear region.

[0093] In a plan view, the hole 24 for connecting the p-side electrode 15 and the p-side pad electrode 20 is included in the p-side pad electrode 20 and has a shape obtained by reducing the right-angled isosceles triangle of the p-side pad electrode 20 .

[0094] Figure 8 The electrode shapes shown are as follows. Figure 8 The electrode shape shown is consistent with Figure 6 and Figure 7 Examples of different electrode shapes are shown. Figure 8 In Figure 7The plan view shape of the hole 23 in the n-side electrode 16 is changed from a circle to a square, so that the diameter and interval of the dots are reduced. Figure 7 same.

[0095] By making the electrode shape Figure 6 to Figure 8 In any of the above-mentioned methods, the sum of the areas of the p-side pad electrode 20 and the n-side pad electrode 21 can be increased, and heat dissipation can be improved.

[0096] In the light emitting element 2 of the above-described modified embodiment, the area of ​​the p-side electrode 15 can also be set to 0.75 mm 2 As described above, the light output and life can be improved, and in particular, the light output and life required to replace the mercury lamp can be improved.

[0097] (Second embodiment)

[0098] Fig. 9 2 is a diagram showing the structure of the light emitting device 3 according to the second embodiment, and is a cross-sectional view perpendicular to the base. Fig. 9 As shown, the light emitting device 3 of the second embodiment has a light emitting element 100 that emits ultraviolet light and a base 101 formed in a flat plate shape. The light emitting element 100 can use the light emitting element of the first embodiment. In particular, the thickness of the substrate of the light emitting element 100 is preferably 400 μm or more. This is because the light extraction efficiency of light taken out from the side is improved, and the light output is improved by reflection formed by the first reflective layer 105 described later. The thickness of the substrate of the light emitting element 100 is more preferably 600 μm or more, and further preferably 900 μm or more. There is no particular upper limit on the thickness, but it is preferably 2000 μm or less in consideration of mass productivity and processability.

[0099] The light emitting element 100 is flip-chip mounted on a base 101. The light emitting element 100 has a p-side pad electrode 100a and an n-side pad electrode 100b. The p-side pad electrode 100a and the n-side pad electrode 100b are bonded to two surface electrode layers 103 of the base 101 via bonding electrodes 108a and 108b, respectively.

[0100] The base 101 includes a substrate layer 102 , a surface electrode layer 103 on the substrate layer 102 , a back electrode layer 104 provided on the back surface of the substrate layer 102 , a first reflective layer 105 , and a second reflective layer 106 . Fig.10 This is a diagram showing the base 101 as viewed from above.

[0101] The substrate layer 102 is formed of a flat plate made of ceramic and is formed in a square shape in a plan view. The ceramic is preferably a material with high thermal conductivity. This is to efficiently conduct the heat of the light emitting element 100 to the outside. For example, AlN is preferably used.

[0102] The surface electrode layer 103 is provided in two parts on the surface of the substrate layer 102. The two surface electrode layers 103 are connected to the p-side pad electrode 100a and the n-side pad electrode 100b of the light emitting element 100 via the bonding electrodes 108a and 108b. The two surface electrode layers 103 are made of Au, for example.

[0103] like Fig.10 As shown, in the plan view, two surface electrode layers 103 are arranged in the central part of the square of the base 101. The two surface electrode layers 103 have a shape similar to a rectangle and are arranged at intervals. In addition, a notch is provided in a stepped shape at the corner of each rectangle for alignment of the light emitting element 100. In the plan view, the two surface electrode layers 103 are partially present at the outer side than the side end face 109 of the light emitting element 100.

[0104] The back electrode layer 104 is provided in two parts on the back side of the substrate layer 102. The two back electrode layers 104 are connected to the two surface electrode layers 103 via the holes 107. The two back electrode layers 104 are electrically connected to the outside. The two back electrode layers 104 are made of Au, for example.

[0105] The second reflective layer 106 is provided in a predetermined region on the surface of the substrate layer 102. The second reflective layer 106 is a layer for reflecting the ultraviolet light emitted from the light emitting element 100 upward to improve the light output. The second reflective layer 106 is composed of Au, for example. The second reflective layer 106 is composed of the same material as the surface electrode layer 103, and therefore, the second reflective layer 106 and the surface electrode layer 103 can be formed at the same time.

[0106] In the plan view, Fig.10 As shown in FIG. 1 , the second reflective layer 106 has a square ring-shaped outer shape. The surface electrode layer 103 is located inside the inner circumference of the ring constituting the second reflective layer 106 .

[0107] The first reflective layer 105 is formed in a predetermined plan view shape on the surface electrode layer 103, the substrate layer 102, and the second reflective layer 106. The first reflective layer 105 is a layer for reflecting the ultraviolet light emitted from the light emitting element 100 upward to improve light output.

[0108] like Fig.11 As shown, the first reflective layer 105 has a structure in which a first insulating layer 105A, a metal reflective layer 105B, and a second insulating layer 105C are stacked in this order from the substrate layer 102 side.

[0109] The reflectivity of the first reflective layer 105 is 50% or more. Here, the reflectivity is the reflectivity of ultraviolet light of the emission wavelength of the light-emitting element 100, and the reflectivity is the reflectivity under vertical incidence. Hereinafter, the reflectivity has the same meaning unless otherwise specified. The reflectivity is more preferably 70% or more, and even more preferably 90% or more.

[0110] The first insulating layer 105A is a layer made of an insulator. The first insulating layer 105A is, for example, made of SiO2. The first insulating layer 105A is a layer provided to ensure the insulation between the surface electrode layer 103 and the metal reflective layer 105B. This is because the first reflective layer 105 is also provided on the surface electrode layer 103, and therefore, the bottom layer needs to be an insulator. The thickness of the first insulating layer 105A is sufficient to maintain the insulation between the surface electrode layer 103 and the metal reflective layer 105B, and is, for example, 500nm.

[0111] The metal reflective layer 105B is a layer made of a metal having a reflectivity of 50% or more. The metal reflective layer 105B is more preferably 60% or more, and further preferably 80% or more. For example, the metal reflective layer 105B can use Al, Mg, Ru, Rh, or an alloy containing them as main components. In particular, Al, Mg, or an alloy containing them as main components is preferred from the perspective of high reflectivity. The thickness of the metal reflective layer 105B can be a thickness that sufficiently reduces the transmittance of the metal reflective layer 105B. For example, it can be 50 nm or more.

[0112] The second insulating layer 105C is a layer made of an insulator. The second insulating layer 105C is made of, for example, SiO 2 . The second insulating layer 105C is a layer provided to protect the metal reflective layer 105B. The thickness of the second insulating layer 105C is, for example, 200 nm.

[0113] In a plan view, the first reflective layer 105 is formed by Fig.10 In other words, in a plan view, the first reflective layer 105 is provided in all regions of the square region of the base 101 except the region of the light emitting element 100 (all regions that are more than 0 μm outward from the side end face 109 of the light emitting element 100). If the substrate of the light emitting element 100 is thicker, the output of ultraviolet light from the side end face 109 increases, but the ultraviolet light can be reflected upward by the first reflective layer 105, and the light output can be improved.

[0114] In addition, in the second embodiment, the first reflective layer 105 is provided in all regions that are more than 0 μm outward from the side end face 109 of the light emitting element 100, but the present invention is not limited thereto. The first reflective layer 105 may be provided at least in a region that is more than 0 μm and less than 500 μm outward from the side end face 109 of the light emitting element 100. In such a region, the radiation intensity of the ultraviolet light emitted from the light emitting element 100 becomes stronger. Therefore, if the first reflective layer 105 is provided in such a region, the ultraviolet light emitted from the light emitting element 100 can be efficiently reflected upward by the first reflective layer 105, and the light output can be improved.

[0115] In the second embodiment, the first reflective layer 105 has a structure in which the metal reflective layer 105B reflects light, but the first reflective layer 105 may also have a structure in which the metal reflective layer 105B reflects light. Alternatively, the first reflective layer 105 may have a structure in which the metal reflective layer 105B reflects light, or a combination of the metal reflective layer 105B and the metal reflective layer 105B reflects light. For example, a DBR reflective layer may be provided between the metal reflective layer 105B and the second insulating layer 105C, or a DBR reflective layer may be provided instead of the second insulating layer 105C.

[0116] In particular, from the perspective of the angular dependence of the reflectivity, it is preferred that the first reflective layer 105 is configured as a structure composed of a DBR reflective layer and a metal reflective layer 105B. For the DBR reflective layer, the reflectivity is angularly dependent, and there is a case where the reflectivity is reduced depending on the incident angle. On the other hand, the metal reflective layer 105B does not have the angular dependence of the reflectivity. Therefore, the first reflective layer 105 has a structure composed of a DBR reflective layer and a metal reflective layer 105B, so that the reflectivity can be increased regardless of the incident angle.

[0117] The DBR reflective layer is a layer of a DBR structure obtained by alternately stacking two or more materials with different refractive indices at a predetermined thickness. It is preferred that the reflectivity of the DBR reflective layer be set to be 90% or more. Preferably, it is 95%, and more preferably, it is 98% or more. The DBR reflective layer is composed of materials such as SiO2, TiO2, HfO2, Nb2O5, ZrO2, MgF2, etc.

[0118] As described above, in the light emitting device 3 of the second embodiment, the first reflective layer 105 is provided in a region at least 500 μm or less outward from the side end surface 109 of the light emitting element 100. Therefore, the ultraviolet light emitted from the light emitting element 100 can be efficiently reflected upward by the first reflective layer 105, and the light output can be improved.

[0119] Next, experimental results related to the second embodiment will be described.

[0120] Experiment 1

[0121] For the light emitting device 3 of the second embodiment, the radiation intensity of the surface of the base 101 when the light emitting element 100 emits light is obtained by simulation. The base 101 is a square with a side of 3.5 mm in plan view. The light emitting element 100 is a square with a side of 1.06 mm in plan view and a thickness of 950 μm.

[0122] Fig.12 is the radiation intensity (W / μm 2 ). Fig.12 As shown, it can be seen that there is a region with high radiation intensity in the region that is 500 μm or less outside the side end face 109 of the light emitting element 100. As a result, it can be seen that by providing a reflective layer in the region that is 500 μm or less outside the side end face 109 of the light emitting element 100, it is possible to efficiently achieve an improvement in light output.

[0123] Experiment 2

[0124] In the second embodiment, the range of the first reflective layer 105 is changed to a region that is 500 μm or more and 1220 μm or less from the side end face 109 of the light emitting element 100 to the outside, and the light output is calculated. In addition, the output improvement rate relative to the case where the first reflective layer 105 is not provided is calculated. The thickness of the sapphire substrate of the light emitting element 100 is 400 μm and 950 μm. The other conditions are the same as those of Experiment 1. As a result, when the thickness of the sapphire substrate is 400 μm, the output improvement rate is 0.88%, and when the thickness of the sapphire substrate is 950 μm, the output improvement rate is 2.85%. As a result, it can be seen that the thicker the substrate, the higher the effect of improving the light output obtained by the first reflective layer 105.

[0125] Experiment 3

[0126] In the second embodiment, the range of the first reflective layer 105 is changed to a region that is more than 0 μm and less than 1220 μm outward from the side end face 109 of the light emitting element 100, and the light output is calculated. In addition, the output improvement rate relative to the case where the first reflective layer 105 is not provided is calculated. The thickness of the sapphire substrate of the light emitting element 100 is 950 μm. The other conditions are the same as those of Experiment 1. As a result, the output improvement rate is 3.88%. According to the comparison with Experiment 2, when the first reflective layer 105 is provided in a region that is more than 500 μm and less than 1220 μm outward from the side end face 109, the light output improvement effect per unit area is improved. Therefore, it is found that it is preferable to provide the first reflective layer 105 at least in a region which is 0 μm or more and 500 μm or less outward from the side end surface 109 of the light emitting element 100 .

Claims

1. A light-emitting element, using a Group III nitride semiconductor containing Al and having a light emission wavelength of 200 nm to 280 nm, wherein the light-emitting element has: substrate; a semiconductor layer formed by stacking an n-type layer, a light-emitting layer, and a p-type layer in order from the substrate side on the substrate; a hole, which is disposed in a predetermined area on the surface of the p-type layer and has a depth reaching the n-type layer; A p-side electrode, which is disposed on the p-type layer and in contact with the p-type layer, and has a reflectivity of ultraviolet light of a light emission wavelength of 50% or more; as well as an n-side electrode disposed on or above the n-type layer exposed at the bottom surface of the hole, The holes and the n-side electrode have a pattern of a plurality of dots arranged two-dimensionally, The area of ​​the p-side electrode is 0.75 mm 2 above.

2. The light emitting element according to claim 1, characterized in that The diameter of the dots of the n-side electrode is 5 μm to 100 μm, and the distance between the centers of adjacent dots is 50 μm to 200 μm.

3. The light emitting element according to claim 1 or 2, characterized in that: A ratio of the area of ​​the p-side electrode to the total value of the area of ​​the hole and the area of ​​the p-type layer is 70% or more.

4. The light emitting element according to claim 1 or 2, characterized in that: The overall thickness of the light emitting element is greater than or equal to 0.5 mm and less than or equal to 1 mm.

5. The light emitting element according to claim 1 or 2, characterized in that: The device comprises: a p-side pad electrode disposed on or above the p-side electrode and an n-side pad electrode disposed on or above the n-side electrode, The total area of ​​the p-side pad electrode and the n-side pad electrode is 0.7 mm 2 above.

6. The light emitting element according to claim 1 or 2, characterized in that: The area of ​​the p-side electrode, the diameter of the dots of the n-side electrode, and the center-to-center distance of adjacent dots are set so that the optical output becomes 150 mW or more when driven at 350 mA and the life becomes 10,000 hours or more.

7. A light emitting device, characterized in that: have: The light emitting element according to claim 1; and a base on which the light emitting element is flip-chip mounted and a reflective layer is provided on the surface on which the light emitting element is mounted, The reflectivity of the reflective layer to ultraviolet light of the emission wavelength of the light-emitting element is 50% or more. The reflective layer is provided in a region which is at least 0 μm or more and 500 μm or less outward from a side end surface of the light emitting element in a plan view.

8. The light emitting device according to claim 7, characterized in that: The reflective layer is provided in all regions extending outward by 0 μm or more from the side end surface of the light emitting element in a plan view.

9. The light emitting device according to claim 7, characterized in that: The base has a surface electrode layer bonded to the light emitting element. The reflective layer has an insulating layer as a lowermost layer, When the surface electrode layer is viewed in plan, a portion of the surface electrode layer is provided outside a side end surface of the light emitting element.

10. The light emitting device according to claim 7, characterized in that: The reflective layer has: Insulation layer; as well as The metal reflective layer is disposed on or above the insulating layer and is composed of a metal having a reflectivity of 50% or more for ultraviolet light of the emission wavelength of the light emitting element.

11. The light emitting device according to claim 7, characterized in that: The reflective layer includes a DBR reflective layer having a reflectivity of 90% or more with respect to ultraviolet light having a wavelength of light emitted by the light emitting element.

12. The light emitting device according to claim 7, characterized in that: The reflective layer has: Insulation layer; a metal reflective layer, which is disposed on or above the insulating layer and is composed of a metal having a reflectivity of 50% or more for ultraviolet light of the emission wavelength of the light emitting element; and The DBR layer is disposed on or above the metal reflective layer and has a reflectivity of 50% or more for ultraviolet light of the emission wavelength of the light emitting element.

13. The light emitting device according to claim 7, characterized in that: The substrate of the light emitting element has a thickness of 900 μm or more.

14. A light emitting device, characterized in that: have: A light-emitting element using a Group III nitride semiconductor containing Al and having a light emission wavelength of 200 nm to 280 nm; as well as a base on which the light emitting element is flip-chip mounted, and which has a reflective layer provided on the surface on which the light emitting element is mounted and a surface electrode layer bonded to the light emitting element, and the base is formed in a flat plate shape, The reflective layer has an insulating layer as a lowermost layer, When the surface electrode layer is viewed from above, a portion of the surface electrode layer is disposed outside the side end surface of the light emitting element. The reflectivity of the reflective layer to ultraviolet light of the emission wavelength of the light-emitting element is 50% or more. The reflective layer is provided in a region which is at least 0 μm or more and 500 μm or less outward from a side end surface of the light emitting element in a plan view.

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