JP5543164B2 - Light emitting element - Google Patents

Description

  The present invention relates to a light emitting device including a transparent electrode.

  Conventionally, a translucent substrate, an n-type nitride semiconductor layer formed on the translucent substrate, an active layer formed on the n-type nitride semiconductor layer, and a p-type nitride formed on the active layer A semiconductor layer, a mesh-type dielectric layer formed on the p-type nitride semiconductor layer and having a mesh structure having a plurality of open regions from which the p-type nitride semiconductor layer is exposed, a mesh-type dielectric layer, and a p-type A highly reflective ohmic contact layer formed on the open region where the nitride semiconductor layer is exposed, and a p-side bonding electrode and an n-side electrode formed on the highly reflective ohmic contact layer and the n-type nitride semiconductor layer, respectively. There is known a nitride semiconductor light emitting device for flip-chip including the above (see, for example, Patent Document 1).

  The semiconductor light-emitting device described in Patent Document 1 uses a dielectric layer having a mesh structure, and forms a highly reflective ohmic contact layer in the open region of the dielectric layer having the mesh structure, thereby adjacent to the n-side electrode. Since the current concentrated on the portion can be reduced, the forward voltage can be reduced and the light emission efficiency can be improved.

JP 2005-347728 A

  However, the semiconductor light emitting device described in Patent Document 1 has an ohmic contact layer formed on a dielectric layer having a mesh structure and an open region, and a part of the light is reflected by the ohmic contact layer. There is a limit to the amount of light absorbed in the layer.

  Accordingly, an object of the present invention is to provide a light emitting device capable of improving light extraction efficiency.

In order to achieve the above object, the present invention provides a semiconductor composed of a nitride compound semiconductor including a first conductivity type semiconductor layer, a light emitting layer, and a second conductivity type semiconductor layer different from the first conductivity type. A transparent intermediate portion provided on a part of the surface of the second conductivity type semiconductor layer and having a refractive index lower than the refractive index of the second conductivity type semiconductor layer; A transparent intermediate part that totally reflects a part of light at an interface with the second conductive type semiconductor layer; and a refraction of the transparent intermediate part provided on the transparent intermediate part and the second conductive type semiconductor layer. And having a refractive index higher than the refractive index and a refractive index lower than the refractive index of the second conductivity type semiconductor layer, a part of the light from the light emitting layer is totally absorbed at the interface with the second conductivity type semiconductor layer. A transparent electrode to be reflected, and provided above the transparent electrode Comprising a reflective film layer, the that, the transparent intermediate portion is made of a material having a high transmittance than the transmittance of the transparent electrode, wherein there between the reflective layer and the second conductive type semiconductor layer first A plurality of light-emitting elements provided in contact with a two-conductivity type semiconductor layer are provided.

In the light emitting device, the reflective film layer is a metal material or an alloy material that is electrically connected to the transparent electrode , and the plurality of transparent intermediate portions are the second conductive type semiconductor layer or the plane of the transparent electrode. It occupies an area of 10% or more and 40% or less with respect to the viewing area .

  In the light emitting device, the transparent intermediate portion may be formed of a plurality of layers having different refractive indexes.

In the light emitting device, the transparent intermediate portion is preferably made of SiO ₂ or Al ₂ O ₃ , and the transparent electrode is preferably made of ITO.

  In the light emitting device, the plurality of transparent intermediate portions may be periodically disposed on the second conductive type semiconductor layer along a first axis and a second axis orthogonal to the first axis. Good.

  Further, in the light emitting device, the transparent intermediate portion may be provided in a lattice shape on the second conductivity type semiconductor layer.

  In the light-emitting element, the reflective film layer may be provided so as to be covered with an insulating material, and the insulating material may have an opening for electrically connecting the transparent electrode and an external electrode.

  In the light emitting device, at least a part of the plurality of transparent intermediate portions may be provided immediately below the opening.

  The light emitting device according to the present invention can provide a light emitting device capable of improving the light extraction efficiency.

FIG. 1A is a longitudinal sectional view of a light emitting device according to a first embodiment of the present invention. FIG. 1B is a plan view of the light-emitting element according to the first embodiment of the present invention. FIG. 1C is a diagram showing the arrangement of the transparent intermediate portion according to the first embodiment of the present invention. FIG. 2A is a schematic diagram of a manufacturing process of the light-emitting element according to the first embodiment of the present invention. FIG. 2B is a schematic diagram of a manufacturing process of the light-emitting element according to the first embodiment of the present invention. FIG. 3 is a longitudinal sectional view of a light emitting device according to the second embodiment of the present invention. FIG. 4 is a diagram showing the arrangement of the transparent intermediate portion of the light emitting device according to the third embodiment of the present invention. FIG. 5 is a diagram showing the arrangement of the transparent intermediate portion of the light emitting device according to the fourth embodiment of the present invention. FIG. 6 is a diagram showing the arrangement of the transparent intermediate portion of the light emitting device according to the fifth embodiment of the present invention. It is a figure which shows arrangement | positioning of the transparent intermediate part of the light emitting element which concerns on the 6th Embodiment of this invention.

[First Embodiment]
FIG. 1A shows an outline of a longitudinal section of a light emitting element according to the first embodiment of the present invention, and FIG. 1B shows an outline of an upper surface of the light emitting element according to the first embodiment of the present invention. In addition, FIG. 1A has shown the outline | summary of the longitudinal cross-section in the AA of FIG. 1B.

(Configuration of Light-Emitting Element 1)
As shown in FIG. 1A, the light-emitting element 1 according to the first embodiment of the present invention includes a sapphire substrate 10 having a C-plane (0001), a buffer layer 20 provided on the sapphire substrate 10, and a buffer layer 20. An n-side contact layer 22 that is an n-type semiconductor layer provided thereon, an n-side cladding layer 24 provided on the n-side contact layer 22, a light emitting layer 25 provided on the n side cladding layer 24, and a light emitting layer 25 A semiconductor laminated structure including a p-side cladding layer 26 provided on the upper surface and a p-side contact layer 28 which is a p-type semiconductor layer provided on the p-side cladding layer 26 is provided.

  The light-emitting element 1 includes an n-electrode 32 provided on the n-side contact layer 22 exposed by etching from the p-side contact layer 28 to at least the surface of the n-side contact layer 22, and the p-side contact layer 28. The transparent intermediate portion 40 provided in the upper partial region, the transparent electrode 30 as the p-electrode provided on the p-side contact layer 28 provided with the transparent intermediate portion 40, and the reflective film provided on the transparent electrode 30 A reflective electrode 50 as a layer, a p-side junction electrode 60 provided on the reflective electrode 50, and an n-side junction electrode 62 provided on the n-electrode 32 are provided. The p-side bonding electrode 60 and the n-side bonding electrode 62 can be formed having a barrier layer and a solder layer from the reflective electrode 50 or the n-electrode 32 side.

Here, the buffer layer 20, the n-side contact layer 22, the n-side cladding layer 24, the light emitting layer 25, the p-side cladding layer 26, and the p-side contact layer 28 are each made of a group III nitride compound semiconductor. It is a layer. The group III nitride compound semiconductor is, for example, a quaternary group III nitride of Al _x Ga _y In _1-xy N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). A compound compound semiconductor can be used, and a binary group III nitride compound semiconductor such as AlN, GaN, or InN, Al _x Ga _1-x N, Al _x In _1-x N, or Ga _x In _A ternary group III nitride compound semiconductor of _1-xN (where 0 <x <1) can also be used.

  In the present embodiment, the buffer layer 20 is made of AlN. The n-side contact layer 22 and the n-side cladding layer 24 are each formed from n-GaN doped with a predetermined amount of n-type dopant (for example, Si). The light emitting layer 25 has a multiple quantum well structure formed of InGaN / GaN / AlGaN. Further, the p-side cladding layer 26 and the p-side contact layer 28 are each formed from p-GaN doped with a predetermined amount of p-type dopant (for example, Mg).

In the present embodiment, the transparent electrode 30 is formed including an oxide semiconductor having a refractive index higher than that of the transparent intermediate portion 40. The transparent electrode 30 can be formed from, for example, ITO (Indium Tin Oxide). The transparent electrode 30 is formed with a thickness of 50 nm or more and 500 nm or less, for example. The transparent intermediate portion 40 is made of a material having a refractive index lower than that of the p-side contact layer 28 and the transparent electrode 30. The transparent intermediate portion 40 is made of a material having a transmittance of light in the wavelength range emitted from the light emitting layer 25 that is equal to or higher than the transmittance of the material constituting the transparent electrode 30. For example, the transparent intermediate portion 40 can be formed of an insulating material such as silicon dioxide (SiO ₂ ) or alumina (Al ₂ O ₃ ). That is, the transparent intermediate portion 40 according to the present embodiment configures the refractive index of the material constituting the p-side contact layer 20 and the transparent electrode 30 for the purpose of totally reflecting light incident on the transparent intermediate portion 40. with a material having a refractive index lower than the refractive index of the material, for the purpose of not absorb excess light transparent intermediate portion 40 has a higher transmittance than the transmittance of the material constituting the transparent electrode 30 Constructed using materials. In addition, the transparent intermediate part 40 can also be made into the laminated structure containing the predetermined number of repeating units of the pair of the 1st transparent intermediate part and 2nd transparent intermediate part of a mutually different refractive index.

  As shown in FIGS. 1A and 1B, the n-electrode 32 is formed on the n-side contact layer 22 and is formed from a mesa portion composed of a plurality of compound semiconductor layers from the n-side cladding layer 24 to the p-side contact layer 28. It is provided at a remote location. Specifically, as indicated by a broken line in FIG. 1B, the n-electrode 32 is formed in a comb shape as a whole in plan view, and extends along a predetermined side of the light emitting element 1 and emits light from the side. And a plurality of thin line portions 32 a to 32 f extending toward the opposite side of the element 1. Each thin wire | line part 32a-32f is arranged in parallel mutually, and the base end is mutually electrically connected by the side part. The n-side junction electrode 62 that is electrically connected to the n-electrode 32 is provided at two adjacent corners of the light emitting element 1.

  For example, the n-electrode 32 is formed to include at least one metal selected from the group consisting of Ni, Cr, Ti, Al, Pd, Pt, Au, V, Ir, and Rh. For example, when the n-side contact layer 22 is formed of n-type GaN, the n-electrode 32 may be formed including an Ni layer and an Au layer from the n-side contact layer 22 side, or the n-side contact layer You may form including a Cr layer and Au layer from the 22 side.

  The transparent electrode 30 is provided on the entire p-side contact layer 28 so as to cover the transparent intermediate portion 40. Specifically, as shown by a broken line in FIG. 1B, the transparent electrode 30 has a plurality of strip portions 30a to 30e arranged between the thin wire portions 32a to 32f and parallel to each other. One end is electrically connected to each other. That is, the transparent electrode 30 has a comb shape opposite to the n electrode 32. In FIG. 1B, since the p-side bonding electrode 60 is exposed on the surface, the transparent electrode 30 and the transparent intermediate portion 40 cannot be directly confirmed.

  The reflective electrode 50 on the transparent electrode 30 is formed of a metal material that reflects light emitted from the light emitting layer 25. The reflective electrode 50 can be formed from, for example, a metal material containing Ag, Rh, and Al, or an alloy material of Ag, Rh, and / or Al.

  The p-side bonding electrode 60 on the reflective electrode 50 is formed above each of the strip portions 30a to 30e of the transparent electrode 30, and is formed in a strip shape in plan view. Note that the n-side bonding electrodes 62 provided at the two corners of the light emitting element 1 are formed in a substantially square shape in plan view. The p-side junction electrode 60 and the n-side junction electrode 62 have a metal layer mainly composed of Ti as a barrier layer at a contact portion between the reflective electrode 50 and the n-electrode 32. The p-side bonding electrode 60 and the n-side bonding electrode 62 can have a solder layer formed of a eutectic material, for example, AuSn, on the barrier layer. The solder layer can be formed by, for example, a vacuum evaporation method (for example, an electron beam evaporation method or a resistance heating evaporation method), a sputtering method, a plating method, a screen printing method, or the like. The solder layer can also be formed from eutectic solder made of a eutectic material other than AuSn or lead-free solder such as SnAgCu.

  Specifically, the barrier layer is formed on the first barrier layer in contact with the n-electrode 32 and the reflective electrode 50, and the second barrier layer is formed on the first barrier layer, and suppresses the diffusion of the material constituting the solder layer. And a barrier layer. The first barrier layer is formed of a material that has ohmic contact with the material that forms the n-electrode 32 and the material that forms the reflective electrode 50 and has good adhesion, and is mainly formed of, for example, Ti. The second barrier layer is formed of a material that can prevent the material constituting the solder layer from diffusing to the n electrode 32 and the reflective electrode 50 side, and is mainly formed of Ni, for example.

  Note that the barrier layers of the p-side junction electrode 60 and the n-side junction electrode 62 may include a plurality of pair layers, with the first barrier layer and the second barrier layer as one pair layer. When the barrier layer includes a plurality of pair layers, diffusion of the material constituting the solder layer can be further suppressed. The film thickness of the first barrier layer of the barrier layer is, for example, about 150 nm, and the film thickness of the second barrier layer is, for example, about 100 nm or 150 nm. Furthermore, the solder layer is formed to have a thickness of 2 μm or more and 20 μm or less, for example.

(Details of arrangement of transparent intermediate portion 40)
FIG. 1C partially shows an outline of the arrangement of the transparent intermediate portion of the light emitting device according to the first embodiment of the present invention.

  The transparent intermediate portion 40 according to the present embodiment is provided on a part of the surface of the p-side contact layer 28. The transparent electrode 30 is in electrical contact with the p-side contact layer 28 through the non-formation region of the transparent intermediate portion 40.

  Specifically, the transparent intermediate portion 40 according to the present embodiment has a plurality of transparent intermediate portions 40a to 40i, and each transparent intermediate portion 40 is regularly arranged on the p-side contact layer 28 in plan view. The For example, the plurality of transparent intermediate portions are formed on the p-side contact layer 28 with a first axis (vertical axis in FIG. 1C) and a second axis orthogonal to the first axis (lateral direction in FIG. 1C). Are arranged periodically along the first axis and the second axis. Here, in FIG. 1C, for the sake of explanation, the first axis is the vertical direction and the second axis is the horizontal direction, but actually, as shown in FIG. 1B, the first axis and the second axis are The belt-shaped portions 30a to 30e are inclined by a predetermined angle (45 degrees in FIG. 1B). In the present embodiment, the interval between the transparent intermediate portions adjacent to each other with respect to the first axis and the second axis is constant, and the transparent intermediate portions 40a to 40i are provided at positions corresponding to the lattice points of the matrix. It has been. Note that the shape of the transparent intermediate portions 40a to 40i in plan view may be a circle or a polygon (for example, a triangle, a quadrangle, a pentagon, a hexagon, or the like). Further, the angle formed between the first axis and the second axis may be an acute angle.

  The diameters of the transparent intermediate portions 40a to 40i and the distance between the transparent intermediate portions are minimized in resistance increase between the transparent electrode 30 and the p-side contact layer 28, and between the p-side contact layer 28 and the transparent intermediate portion 40. For the purpose of maximizing the ratio of total reflection of light emitted from the light emitting layer 25 at the interface, for example, the diameter is 2 μm or more and 20 μm or less, the thickness is 50 nm or more and 500 nm or less, and the interval is 2 μm or more and 50 μm or less. It is preferable that Further, the ratio of the area of the transparent intermediate portion 40 to the area of the p-side contact layer 28 or the transparent electrode 30 in a plan view can be 10% or more and 40% or less.

  The light emitting element 1 configured as described above is a flip chip type light emitting diode (LED) that emits light having a wavelength in a blue region. For example, the light emitting element 1 emits light having a peak wavelength of 450 nm when the forward voltage is 3.2 V and the forward current is 350 mA. The light emitting element 1 is formed in a substantially square shape in plan view, and has a vertical dimension and a horizontal dimension of approximately 1 mm, for example. Since the p-electrode and the n-electrode are provided on the same surface side in the light-emitting element 1, in addition to the flip chip type LED as described above, a face-up type LED, a vertical light-emitting type LED (that is, a growth type) The present invention can also be applied to an LED formed by forming a semiconductor multilayer structure on a substrate, attaching a heterogeneous substrate to the surface of the semiconductor multilayer structure on the opposite side of the growth substrate, and then removing the growth substrate.

  The layers from the buffer layer 20 to the p-side contact layer 28 provided on the sapphire substrate 10 are, for example, metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (Molecular Beam Epitaxy): MBE), halide vapor phase epitaxy (HVPE), and the like. Here, the buffer layer 20 is formed of AlN, but the buffer layer 20 can also be formed of GaN. In addition, the quantum well structure of the light emitting layer 25 may be a single quantum well structure or a strained quantum well structure instead of a multiple quantum well structure.

  Furthermore, the light emitting element 1 may be an LED that emits light having a peak wavelength in the ultraviolet region, the near ultraviolet region, or the green region, but the region of the peak wavelength of the light emitted by the LED is not limited thereto. In other modified examples, the planar dimension of the light emitting element 1 is not limited to this. For example, the planar dimension of the light emitting element 1 can be designed such that the vertical dimension and the horizontal dimension are 300 μm, respectively, and the vertical dimension and the horizontal dimension can be different from each other.

(Manufacturing process of light-emitting element 1)
2A to 2B show an example of a manufacturing process of the light-emitting element according to the first embodiment. Specifically, FIG. 2A (a) is a longitudinal sectional view before etching for exposing the surface of the n-side contact layer is performed. FIG. 2B is a longitudinal sectional view after the etching for exposing the surface of the n-side contact layer is performed. FIG. 2A (c) is a longitudinal sectional view showing a state in which a mask is formed on the p-side contact layer. And (a) of FIG. 2B is a longitudinal cross-sectional view after forming a transparent intermediate part. FIG. 2B is a longitudinal sectional view after forming the transparent electrode and the n-electrode. FIG. 2B (c) is a longitudinal sectional view after the bonding electrode is formed.

  First, a sapphire substrate 10 is prepared, and an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer are stacked in this order on the sapphire substrate 10 to form a semiconductor stacked structure. Specifically, the buffer layer 20, the n-side contact layer 22, the n-side cladding layer 24, the light emitting layer 25, the p-side cladding layer 26, and the p-side contact layer 28 are formed on the sapphire substrate 10. Epitaxial growth is sequentially performed to form an epitaxial growth substrate (semiconductor laminated structure forming step).

  Subsequently, a mask 200 made of a photoresist is formed on the p-side contact layer 28 of the epitaxial growth substrate by using a photolithography technique (FIG. 2A (a)). Next, after etching a part of the region excluding the portion where the mask 200 is formed from the p-side contact layer 28 to the surface of the n-side contact layer 22, the mask 200 is removed. Thereby, a mesa portion composed of a plurality of compound semiconductor layers from the n-side cladding layer 24 to the p-side contact layer 28 is formed, and a part of the surface of the n-side contact layer 22 is exposed (FIG. 2A (b)). , Removal step). In the removal step, etching is performed to a part of the n-side contact layer 22 for the purpose of completely removing the portion from the n-side cladding layer 24 to the p-side contact layer 28 where the mask 200 is not formed.

Thereafter, the transparent intermediate portion 40 is formed so as to cover the exposed surface of the n-side contact layer 22, the side surface of the mesa portion, and the surface of the p-side contact layer 28 (that is, the upper surface of the mesa portion). For example, it can be formed by a vacuum evaporation method using SiO ₂ as a material constituting the transparent intermediate portion 40. Then, a mask 202 is formed on a region where the transparent intermediate portion 40 is left, and etching is performed on a portion where the mask 202 is not formed. Thereby, as shown to Fig.2B (a), the transparent intermediate part 40 is formed (transparent intermediate part formation process).

  Subsequently, the transparent electrode 30 is formed on the p-side contact layer 28 on which the transparent intermediate portion 40 is formed (transparent electrode forming step). For example, the transparent electrode 30 is formed so as to cover the exposed surface of the n-side contact layer 22, the side surface of the mesa portion, and the surface of the p-side contact layer 28 on which the transparent intermediate portion 40 is formed. Then, a transparent electrode 30 is formed by forming a mask above the p-side contact layer 28 and etching the portion where the mask is not formed. The transparent electrode 30 can also be formed by a sputtering method, a CVD method, a vapor deposition method, a sol-gel method, or the like.

  Next, the n-electrode 32 is formed in a predetermined partial region on the surface of the n-side contact layer 22 by using a vacuum deposition method and a photolithography technique (FIG. 2B (b), n-electrode forming step). In addition, after forming the n electrode 32 and the transparent electrode 30, ohmic contact and adhesion between the n-side contact layer 22 and the n-electrode 32 and between the transparent electrode 30 and the p-side contact layer 28 are obtained. In order to ensure, heat treatment for a predetermined time can be performed at a predetermined temperature and a predetermined atmosphere.

  Subsequently, the reflective electrode 50 is formed on the transparent electrode 30 using a vacuum deposition method and a photolithography technique (reflective electrode forming step). Then, the p-side bonding electrode 60 is formed on the reflective electrode 50 and the n-side bonding electrode 62 is formed on the n-electrode 32 using a vacuum deposition method and a photolithography technique (bonding electrode forming step). The bonding electrode forming step includes a barrier layer forming step of forming a barrier layer in contact with the reflective electrode 50 and a barrier layer in contact with the n electrode 32, and a solder layer forming step of forming a solder layer on the barrier layer. Can be included. Thereby, the p-side junction electrode 60 and the n-side junction electrode 62 composed of the barrier layer and the solder layer are formed, and the light emitting device 1 shown in FIG. 2B (c) is manufactured.

  The light emitting element 1 formed through the above steps is mounted by flip chip bonding at a predetermined position on a substrate made of ceramic or the like in which a wiring pattern of a conductive material is formed in advance. And the light emitting element 1 mounted on the board | substrate can be packaged as a light emitting device by sealing integrally with a sealing material.

(Effects of the first embodiment)
In the light emitting element 1 according to the present embodiment, a transparent intermediate portion 40 formed by including a material having a lower refractive index than that of the material constituting the transparent electrode 30 is provided in part on the p-side contact layer 26. Since the transparent electrode 30 is formed on the p-side contact layer 26 provided with the transparent intermediate portion 40 so as to cover the transparent intermediate portion 40, the current diffusion in the horizontal direction (that is, the sheet direction (horizontal direction)) is transparent. As with the case where the portion 40 is not provided, the number can be reduced, and even if the transparent intermediate portion 40 is provided, the drive voltage of the light emitting element 1 can be prevented from increasing. Furthermore, since the light-emitting element 1 according to the present embodiment has the above-described configuration, the transparent electrode 30 may be formed from a material that is difficult to make ohmic contact with the p-side contact layer 28, and the resistance is low. The transparent electrode 30 may be formed from a material that is somewhat high. Furthermore, since the light emitting element 1 can form the reflective electrode 50 using a material with high reflectance, light absorption in the reflective electrode 50 can be reduced. Thereby, in the light emitting element 1 which concerns on this Embodiment, the breadth of selection of a material with high reflectance can be expanded.

  In the light emitting element 1 according to the present embodiment, the transparent intermediate portion 40 is provided in a part between the p-side contact layer 26 and the transparent electrode 30, and therefore the p-side of the light emitted from the light-emitting layer 25. A part of the light incident on the interface between the contact layer 26 and the transparent intermediate portion 40 can be totally reflected at the interface. Also, part of the light can be totally reflected at the interface between the transparent electrode 30 and the p-side contact layer 26. Thereby, since the light which injects into the transparent electrode 30 and the reflective electrode 50 reduces, the light absorbed in the transparent electrode 30 and the reflective electrode 50 can be reduced. Since the transparent electrode 30 is in contact with the p-side contact layer 28 as a unit in the region excluding the transparent intermediate portion 40, an increase in contact resistance of the transparent electrode 30 can be suppressed. Therefore, according to the light emitting element 1 according to the present embodiment, it is possible to improve the light extraction efficiency while keeping the contact resistance of the transparent electrode 30 low.

[Second Embodiment]
FIG. 3 shows an outline of a longitudinal section of a light emitting device according to the second embodiment of the present invention.

  The light emitting element 2 according to the second embodiment has substantially the same configuration and function as the light emitting element 1 according to the first embodiment, except that the reflective layer 55 that is a reflective film layer is sandwiched between insulating layers. Have Therefore, a detailed description is omitted except for differences.

  The light emitting element 2 according to the second embodiment includes a sapphire substrate 10, a buffer layer 20 provided on the sapphire substrate 10, an n-side contact layer 22 provided on the buffer layer 20, and an n-side contact layer 22. An n-side cladding layer 24 provided on the light-emitting layer 25, a light-emitting layer 25 provided on the n-side cladding layer 24, a p-side cladding layer 26 provided on the light-emitting layer 25, and a p-side contact provided on the p-side cladding layer 26. A semiconductor stacked structure including the layer 28 is provided.

  The light-emitting element 2 includes an n-electrode 32 provided on the n-side contact layer 22 exposed by etching from the p-side contact layer 28 to at least the surface of the n-side contact layer 22, and the p-side contact layer 28. A transparent intermediate portion 40 provided in a part of the upper region; a transparent electrode 30 provided on the p-side contact layer 28 provided with the transparent intermediate portion 40; an exposed n-side contact layer 22; a side surface of the mesa portion; And an insulating layer 70 covering a part of the upper surface of the transparent electrode 30; a reflective layer 55 provided on a part of the insulating layer 70; and p electrically connected to the transparent electrode 30 through an opening 70a of the insulating layer 70. A side junction electrode 60 and an n side junction electrode 62 provided on the n electrode 32 are provided. Here, in the present embodiment, the reflective layer 55 is provided in the insulating layer 70. That is, the reflective layer 55 as the reflective film layer is electrically insulated from the outside.

The reflective layer 55 can be composed of a metal material such as Ag that reflects light emitted from the light emitting layer 25, or a DBR layer having a pair of insulating films having different refractive indexes. The insulating layer 70 is made of an oxide such as SiO ₂ , titanium oxide (TiO ₂ ), alumina (Al ₂ O ₃ ), tantalum pentoxide (Ta ₂ O ₅ ), or an electrically insulating resin material such as polyimide. Can be formed from A plurality of transparent intermediate portions 40 can also be provided preferentially immediately below the opening of the reflective layer 55. In this case, light incident on the bonding electrode 60 having a low reflectance can be reduced, and the light extraction efficiency of the light emitting element 2 can be improved.

  Further, in the light emitting element 2 according to the second embodiment, since the reflective layer 55 is sandwiched between the insulating layers 70, the characteristics of the reflective layer 55 due to electromigration even if a high current is passed through the light emitting element 2. No deterioration occurs.

[Third Embodiment]
FIG. 4 partially shows the arrangement outline of the transparent intermediate portion of the light emitting device according to the third embodiment of the invention.

  The light emitting device according to the third embodiment has substantially the same configuration and function except that the arrangement of the transparent intermediate portion is different from that of the light emitting device 1 according to the first embodiment. Therefore, a detailed description is omitted except for differences.

  A plurality of transparent intermediate portions 40 included in the light emitting element according to the third embodiment are irregularly arranged on the p-side contact layer 28. The shape of the transparent intermediate portion 40 in plan view can be a circle, a polygon, or the like. When the transparent intermediate portion 40 is circular, the diameter thereof can be 2 μm or more and 20 μm or less. For example, the area of the transparent intermediate portion 40 occupying the area of the p-side contact layer 28 or the transparent electrode 30 in a plan view. The ratio can be 10% or more and 40% or less.

[Fourth Embodiment]
FIG. 5 partially shows an outline of the arrangement of the transparent intermediate portion of the light emitting device according to the fourth embodiment of the present invention.

  The light emitting device according to the fourth embodiment has substantially the same configuration and function, except that the shape of the transparent intermediate portion is different from that of the light emitting device 1 according to the first embodiment. Therefore, a detailed description is omitted except for differences.

  The transparent intermediate portion 42 included in the light emitting device according to the fourth embodiment is not integrally formed with a plurality of portions on the p-side contact layer 28, but is integrally formed as a whole. Specifically, the transparent intermediate part 42 is provided in a lattice shape in plan view. Here, the lattice is a shape formed by combining a plurality of straight lines so as to intersect each other on a predetermined plane, and an angle α formed by the two intersecting straight lines is 0 ° <α ≦ 90 °. However, the lattice point is formed by two straight lines. In the present embodiment, α is 90 °. The shape of the transparent intermediate portion 42 is arbitrary. For example, the shape of the region where the p-side contact layer 28 is exposed can be rectangular, polygonal, circular, or the like in plan view, and is exposed. The shapes of the plurality of regions may have different shapes.

[Fifth Embodiment]
FIG. 6 partially shows an outline of the arrangement of the transparent intermediate portion of the light emitting device according to the fifth embodiment of the invention.

  The light emitting device according to the fifth embodiment has substantially the same configuration and function, except that the shape of the transparent intermediate portion is different from that of the light emitting device 1 according to the first embodiment. Therefore, a detailed description is omitted except for differences.

  The transparent intermediate portion included in the light emitting element according to the fifth embodiment is formed by having a dot-like transparent intermediate portion 44 and a connecting portion 46 provided between the dot-like transparent intermediate portions 44. For example, the dot-shaped transparent intermediate portion 44 is provided in a circular shape in a plan view at a position corresponding to a lattice point of the matrix, and the connecting portion 46 is provided in a line shape in a plan view on a line connecting the lattice points. . The connecting unit 46 connects the other lattice point having the shortest linear distance from the one lattice point to the other lattice point among the other lattice points adjacent to the one lattice point.

[Sixth Embodiment]
FIG. 7 partially shows the arrangement outline of the transparent intermediate portion of the light emitting device according to the sixth embodiment of the present invention.

  The light emitting device according to the sixth embodiment has substantially the same configuration and function except that the shape of the transparent intermediate portion is different from that of the light emitting device 1 according to the first embodiment. Therefore, a detailed description is omitted except for differences.

  The transparent intermediate portion 48 included in the light emitting element according to the sixth embodiment is formed in a substantially rectangular shape in plan view. The plurality of transparent intermediate portions 48 are arranged on the p-side contact layer 28 at intervals. For example, the ratio of the area of the transparent intermediate portion 40 to the area of the p-side contact layer 28 or the transparent electrode 30 in plan view can be 10% or more and 40% or less.

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1, 2 Light emitting element 10 Sapphire substrate 20 Buffer layer 22 n side contact layer 24 n side clad layer 25 Light emitting layer 26 p side clad layer 28 p side contact layer 30 Transparent electrode 30a, 30b, 30c, 30d, 30e Band-shaped part 32 n Electrode 32a, 32b, 32c, 32d, 32e, 32f Thin wire part 40, 40a, 40b, 40c, 40d Transparent intermediate part 40e, 40f, 40g, 40h, 40i Transparent intermediate part 42 Mesh-like transparent intermediate part 44 Dot-like transparent intermediate part 46 connecting portion 48 transparent intermediate portion 50 reflective electrode 55 reflective layer 60, 62 junction electrode 70 insulating layer 70a opening 200, 202 mask

Claims (8)

A semiconductor multilayer structure comprising a nitride compound semiconductor including a semiconductor layer of a first conductivity type, a light emitting layer, and a semiconductor layer of a second conductivity type different from the first conductivity type;
Part of light from the light emitting layer by being a transparent intermediate part provided on a part of the surface of the second conductivity type semiconductor layer and having a refractive index lower than that of the second conductivity type semiconductor layer A transparent intermediate part that totally reflects at the interface with the semiconductor layer of the second conductivity type,
It provided in the transparent intermediate portion and on said second conductivity type semiconductor layer, having a refractive index lower than the refractive index of the second conductive type semiconductor layer and having a refractive index higher than the refractive index of the transparent intermediate portion A transparent electrode that totally reflects a part of the light from the light emitting layer at the interface with the semiconductor layer of the second conductivity type,
A reflective film layer provided above the transparent electrode,
The transparent intermediate portion, said of a material having a high transmittance than the transmittance of the transparent electrode, in contact with the semiconductor layer of the second conductivity type located between the second conductive type semiconductor layer and the reflective layer A plurality of light emitting elements provided. The reflective film layer is a metal material or alloy material that is electrically connected to the transparent electrode ,
2. The light emitting device according to claim 1, wherein the plurality of transparent intermediate portions occupy an area of 10% to 40% with respect to an area of the second conductive type semiconductor layer or the transparent electrode in a plan view .   The light-emitting element according to claim 1, wherein the transparent intermediate portion includes a plurality of layers having different refractive indexes. The plurality of transparent intermediate portions are made of SiO ₂ or Al ₂ O ₃ ,
The light emitting device according to claim 1, wherein the transparent electrode is made of ITO.   The plurality of transparent intermediate portions are periodically arranged on the second conductive type semiconductor layer along a first axis and a second axis orthogonal to the first axis. The light emitting element of description. The light emitting device according to claim 4, wherein the plurality of transparent intermediate portions are provided in a lattice shape on the second conductivity type semiconductor layer. The reflective film layer is electrically insulated from the outside by being provided in an insulating material,
The light emitting device according to claim 1, wherein the insulating material has an opening that electrically connects the transparent electrode and an external electrode.   The light emitting element according to claim 7, wherein at least a part of the plurality of transparent intermediate portions is provided immediately below the opening.

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