JP2012015156A - Light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element having improved light distribution characteristics.SOLUTION: The light emitting element 1 of the present invention comprises an optical semiconductor layer 11 with multilayered semiconductor layers and a pari of electrodes 12 for applying a voltage to the optical semiconductor layer 11 to cause the optical semiconductor layer 11 to emit light. The pair of electrodes 12 has a one-sided electrode (second electrode) 14 which reflects light emitted by the optical semiconductor layer 11. The one-sided electrode 14 includes a first transparent electrode layer 14a disposed on the optical semiconductor layer 11 and having a refraction index smaller than that of a topmost semiconductor layer included in the optical semiconductor layer 11, a second transparent electrode layer 14b disposed on the first transparent electrode layer 14a and having a refraction index larger than that of the first transparent semiconductor layer 14a, and a reflective electrode layer 14c disposed on the second transparent electrode layer 14b for reflecting light penetrated through the second transparent electrode layer 14b to the optical semiconductor layer 11 direction. The light emitted by the optical semiconductor layer 11 can be favorably diffused in a direction perpendicular to a thickness direction of the optical semiconductor layer 11, which improves light distribution characteristics of the light emitting element 1.

Description

  The present invention relates to a light emitting device using an optical semiconductor layer in a light emitting portion.

  Currently, various light-emitting elements that emit ultraviolet light, blue light, green light, or the like have been proposed in which an optical semiconductor layer is stacked on a single crystal substrate. In particular, in the development of a light emitting element using a nitride semiconductor as an optical semiconductor constituting the optical semiconductor layer, it is necessary to improve the light extraction efficiency to the outside of the light emitting element.

  As a technique for improving the light extraction efficiency of a light emitting element, a technique is disclosed in which a light emitting element having a reflective electrode provided on one main surface of an optical semiconductor layer is mounted on a mounting substrate by a flip chip method (see, for example, Patent Document 1). ).

JP 2010-10591 A

  However, according to the light emitting element described in Patent Document 1, at the interface between the optical semiconductor layer and the reflective electrode, the position where the light emitted from the optical semiconductor layer enters the reflective electrode, and the reflection of the light reflected by the reflective electrode It was almost the same position. Therefore, there is a problem that it is difficult to improve the light distribution characteristic of diffusing the light emitted from the optical semiconductor layer over a wide area.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a light emitting element having improved light distribution characteristics for diffusing light emitted from an optical semiconductor layer over a wide region.

  The light-emitting element of the present invention includes an optical semiconductor layer in which a plurality of semiconductor layers are stacked, and a pair of electrodes for applying a voltage to the optical semiconductor layer and causing the optical semiconductor layer to emit light. And one electrode that reflects light emitted from the optical semiconductor layer, and the one electrode is provided on the optical semiconductor layer more than the uppermost semiconductor layer constituting the optical semiconductor layer. A first transparent electrode layer having a small refractive index, a second transparent electrode layer having a refractive index larger than that of the first transparent electrode layer provided on the first transparent electrode layer, and the second transparent electrode layer And a reflective electrode layer that reflects the light transmitted through the second transparent electrode layer in the direction of the optical semiconductor layer.

  According to the light emitting device of the present invention, the one electrode that reflects the light emitted from the optical semiconductor layer has a refractive index higher than that of the uppermost semiconductor layer constituting the optical semiconductor layer between the optical semiconductor layer and the reflective electrode layer. Since the first transparent electrode layer having a small refractive index and the second transparent electrode layer having a refractive index larger than that of the first transparent electrode layer are included, the light emitted from the optical semiconductor layer is perpendicular to the thickness direction of the optical semiconductor layer. The light distribution characteristics of the light-emitting element can be improved.

It is a figure which shows an example of embodiment of the light-emitting device using the light emitting element of this invention, Fig.1 (a) is a perspective view, FIG.1 (b) cut | disconnected by the AA 'line | wire of (a) FIG. It is a perspective view which shows an example of embodiment of the light emitting element of this invention. It is sectional drawing which shows an example of embodiment of the light emitting element of this invention, and is equivalent to a cross section when cut | disconnected by the B-B 'line | wire of FIG. In an example of embodiment of the light emitting element of this invention, it is an expanded sectional view which shows a part of optical semiconductor layer and a part of 2nd electrode. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the light emitting element of this invention, and is equivalent to a cross section when cut | disconnected by the B-B 'line | wire of FIG. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the light emitting element of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the light emitting element of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the light emitting element of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the light emitting element of this invention.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the example of the following embodiment, A various change can be given in the range which does not deviate from the summary of this invention.

<Light emitting device>
Fig.1 (a) is a perspective view of the light-emitting device 2 which mounted the light emitting element 1 which shows an example of embodiment of this invention. FIG. 1B is a cross-sectional view of the light-emitting device 2 shown in FIG. 1A, and corresponds to a cross section taken along the line AA ′ of FIG.

  As illustrated in FIG. 1B, the light emitting device 2 includes a mounting substrate 4 provided with a wiring conductor 3 and a light emitting element 1 mounted on the mounting substrate 4.

  The mounting substrate 4 is formed by a laminated body in which a first sheet 4a and a second sheet 4b made of, for example, ceramics are laminated. Specifically, the mounting substrate 4 includes a first sheet 4 a having a through hole for forming the substrate recess 5 of the mounting substrate 4, and an electrical connection from the mounting surface 6 on which the light emitting element 1 is mounted to the drawing surface 7. It is formed by pasting together a second sheet 4b having a wiring conductor 3 for ensuring proper conduction.

  For example, when a ceramic material is used as the first sheet 4a and the second sheet 4b, the wiring conductor 3 is formed by a metallized wiring made of a metal material such as tungsten, molybdenum, copper, or silver. And the mounting base | substrate 4 is formed by baking such 1st sheet | seat 4a and 2nd sheet | seat 4b at high temperature.

  The light emitting element 1 is mounted on the wiring conductor 3 on the mounting surface 6 via the bonding electrode 8. In this example, since the light emitting element 1 is mounted on the wiring conductor 3 in a flip chip connection arrangement, the heat generated in the light emitting element 1 can be efficiently radiated to the mounting substrate 1 side.

  The bonding electrode 8 is provided between the first electrode layer and the wiring conductor 3 and between the first electrode layer and the wiring conductor 3 in order to electrically connect the first electrode layer and the second electrode layer of the light emitting element 1 to be described later and the wiring conductor 3. It arrange | positions so that it may interpose between the wiring conductors 3.

The mold resin 9 covers the mounting substrate 4 so as to cover the light emitting element 1 mounted on the mounting substrate 4.
The substrate recess 5 is filled. As the mold resin 9, a translucent insulating material can be used. Thus, by covering the light emitting element 1 with the mold resin 9, the light emitting element 1 can be electrically insulated from the outside, and the reliability of the light emitting device 2 can be improved.

<Light emitting element>
Next, the light emitting element 1 mounted on the light emitting device 2 will be described in detail below with reference to the drawings.

  In FIG. 2, the perspective view of the light emitting element 1 which is an example of embodiment of this invention is shown. 3 is a cross-sectional view of the light-emitting element 1 shown in FIG. 2, and corresponds to a cross section taken along line B-B ′ of FIG.

  As shown in FIG. 2, the light-emitting element 1 includes an optical semiconductor layer 11 in which a plurality of semiconductor layers are stacked on a substrate 10, and a pair of light sources that emit light by applying a voltage to the optical semiconductor layer 11. And an electrode 12.

  For the substrate 10, a material capable of crystal growth of the optical semiconductor layer 11 can be used. For example, a crystalline material such as sapphire, gallium nitride, aluminum nitride, zirconium boride, or zinc oxide can be used. Such a substrate 10 is formed so as to have a square shape in plan view. The thickness of the substrate 10 is set to, for example, 10 μm or more and 1000 μm or less. The planar view shape of the substrate 10 can be set to a polygonal shape such as a quadrangular shape or a pentagonal shape or a circular shape, for example.

  Such a substrate 10 is preferably removed by etching or the like after an optical semiconductor layer 11 described later is grown. As a result, the light emitted from the optical semiconductor layer 11 is less likely to be absorbed by the substrate 10, and the light extraction efficiency can be improved. In addition, by providing a concavo-convex structure on the main surface of the optical semiconductor layer 11 from which the substrate 10 has been removed, it is possible to prevent total reflection on the main surface of the optical semiconductor layer 11 from which the substrate 10 has been removed, thereby improving light extraction efficiency. Can be improved.

  As shown in FIG. 3, the optical semiconductor layer 11 is configured by laminating a plurality of semiconductor layers on a substrate 10. The planar shape of the optical semiconductor layer 11 can be, for example, a polygonal shape such as a square shape or a pentagonal shape, a circular shape, or the like, similar to the planar shape of the substrate 10. The optical semiconductor layer 11 is formed with an overall thickness of, for example, 100 nm or more and 10000 nm or less. Further, the refractive index of each layer of the optical semiconductor layer 11 is set to, for example, 1.80 or more and 2.70 or less when gallium nitride is used.

  As the optical semiconductor layer 11, a group III-V semiconductor can be used. Examples of the group III-V semiconductor include a group III nitride semiconductor, gallium phosphide, gallium arsenide, and the like. Furthermore, as the group III nitride semiconductor, a mixed crystal made of at least one nitride of boron, aluminum, gallium or indium can be used, for example, gallium nitride can be used.

  In the optical semiconductor layer 11, a first semiconductor layer 11a, an active layer 11b, and a second semiconductor layer 11c are stacked as a plurality of semiconductor layers.

  The first semiconductor layer 11a is provided on the substrate 10. Such a first semiconductor layer 11a is made of gallium nitride and has a thickness of, for example, 50 nm or more and 500 μm or less. The first semiconductor layer 11a is given an n-type conductivity type using electrons as a majority carrier, for example, by including silicon as an impurity.

  The active layer 11b is provided on the first semiconductor layer 11a. As the active layer 11b, a multilayer quantum well structure (MQW) in which a quantum well structure including a barrier layer having a wide forbidden band and a well layer having a narrow forbidden band is regularly stacked a plurality of times can be used. As the barrier layer and the well layer, a mixed crystal composed of a nitride of indium and gallium with the composition ratio of indium and gallium adjusted can be used. The active layer 11b configured as described above can emit light having a peak emission intensity at a wavelength of 350 nm to 600 nm, for example.

  The second semiconductor layer 11c is provided on the active layer 11b. The second semiconductor layer 11c is given a p-type conductivity type in which holes are majority carriers by including, for example, magnesium as an impurity. The first semiconductor layer 11a and the second semiconductor layer 11c may be set so as to exhibit opposite conductivity types.

  The optical semiconductor layer 11 is provided with a pair of electrodes 12 for applying light to emit light. The pair of electrodes 12 are electrically connected to the first semiconductor layer 11a, the first electrode 13 as the other electrode, and the second electrode 14 as one electrode electrically connected to the second semiconductor layer 11c. It consists of and.

  The first electrode 13 as the other electrode is provided on the first semiconductor layer 11a. Examples of the first electrode 13 include metals such as aluminum, titanium, nickel, chromium, indium, tin, molybdenum, silver, gold, tantalum, and platinum, alloy films containing these metals, tin oxide, An oxide such as indium oxide or indium tin oxide can be used.

  On the other hand, the second electrode 14 as an electrode is provided on the optical semiconductor layer 11 and is formed of a laminated body in which the first transparent electrode layer 14a, the second transparent electrode layer 14b, and the reflective electrode layer 14c are sequentially laminated. ing.

  The first transparent electrode layer 14 a is provided on the second semiconductor layer 11 c which is the outermost semiconductor layer constituting the optical semiconductor layer 11. The first transparent electrode layer 14a is provided so as to have a refractive index smaller than that of the second semiconductor layer 11c. As the first transparent electrode layer 14a, transparent conductive materials such as indium oxide containing tin oxide (refractive index of 1.30 to 2.40) and zinc oxide (refractive index of 1.90) having a refractive index smaller than that of the second semiconductor layer 11c. Materials can be used.

  The second transparent electrode layer 14b is provided on the first transparent electrode layer 14a so as to have a higher refractive index than the first transparent electrode layer 14a. Therefore, the light transmitted through the first transparent electrode layer 14a can be prevented from being totally reflected at the boundary surface between the first transparent electrode layer 14a and the second transparent electrode layer 14b, and is incident on the second transparent electrode layer 14b. Can be easier. As the second transparent electrode layer 14b, a transparent conductive material such as indium oxide containing tin oxide (refractive index 1.30 to 2.40) or zinc oxide (refractive index 1.90) having a higher refractive index than the first transparent electrode layer 14a is used. Can be used. In addition, when using the transparent conductive material of the same component as the 1st transparent electrode layer 14b as the 2nd transparent electrode layer 14b, the refractive index of the 2nd transparent electrode layer 14b is adjusted by adjusting the ratio of the component of a transparent conductive material. What is necessary is just to make it larger than the refractive index of the 1st transparent conductive layer 14a.

  The reflective electrode layer 14c is provided on the second transparent electrode layer 14b. As the reflective electrode layer 14c, a material capable of reflecting the light emitted from the optical semiconductor layer 11 can be used. For example, aluminum, titanium, nickel, chromium, indium, tin, molybdenum, silver, gold, tantalum can be used. Alternatively, a metal such as platinum or an alloy film containing these metals can be used. Among these materials, by using silver, the light emitted from the optical semiconductor layer 11 can easily reflect light whose emission intensity peaks in the wavelength range of 350 nm or more and 500 nm or less, and the light extraction efficiency can be improved. Can do.

  As described above, the second electrode 14 is formed of a laminated body in which the first transparent electrode layer 14a, the second transparent electrode layer 14b, and the reflective electrode layer 14c are sequentially laminated. It is possible to increase the amount of light diffused in the second direction that is the surface direction of the optical semiconductor layer 11 perpendicular to the first direction. This principle will be described with reference to FIG. In the following description, the thickness direction of the optical semiconductor layer 11 is referred to as “first direction”, and the in-plane direction of the optical semiconductor layer 11 that is perpendicular to the thickness direction of the optical semiconductor layer 11 is referred to as “second direction”. It is called “direction”.

  FIG. 4 is a cross-sectional view in which a part of the optical semiconductor layer 11 and the second electrode 14 is partially enlarged. The incident angle α is an angle formed by the incident direction of light incident on the first transparent electrode layer 14a from the optical semiconductor layer 11 and the virtual perpendicular 15 at the boundary surface between the second semiconductor layer 11c and the first transparent electrode layer 14a. Represents. The refraction angle α2 represents an angle formed by the refraction direction of the light incident on the first transparent electrode layer 14a and the virtual perpendicular 15 at the boundary surface between the second semiconductor layer 11c and the first transparent electrode layer 14a. The refraction angle α3 represents the angle formed by the refraction direction of the light incident on the second transparent electrode layer 14b and the virtual perpendicular 15 at the boundary surface between the first transparent electrode layer 14a and the second transparent electrode layer 14b. ing. The virtual perpendicular line 15 indicates a normal line at the boundary surface between different media when light is incident on different media.

  As shown in FIG. 4, the light incident on the first transparent electrode layer 14a from the second semiconductor layer 11c has a refractive index smaller than that of the second semiconductor layer 11c, as shown in FIG. The light is refracted at a refraction angle α2 that is larger than the incident angle α1. Thereafter, the light that has passed through the first transparent electrode layer 14a enters the second transparent electrode layer 14b having a refractive index larger than that of the first transparent electrode layer 14a at the same angle as the refraction angle α2, and is smaller than the refraction angle α2. Refraction occurs at an angle of refraction angle α3. The light incident on the second transparent electrode layer 14b is reflected at the interface between the second transparent electrode layer 14b and the reflective electrode layer 14c in the first direction of the optical semiconductor layer 11, that is, in the first direction of the optical semiconductor layer 11. Is done.

  Here, the optical path of the light reflected at the interface between the second transparent electrode layer 14b and the reflective electrode layer 14c will be described. As shown in FIG. 4, the optical path of the reflected light is such that the optical path from the optical semiconductor layer 11 to the reflective electrode layer 14c is folded around the reflection position of the reflective electrode layer 14c. The light reflected at the interface between the second transparent electrode layer 14b and the reflective electrode layer 14c travels along the optical path and is extracted outside.

  The light generated in the optical semiconductor layer 11 in this way proceeds in the second direction of the optical semiconductor layer 11 while refracting the first transparent electrode layer 14a and the second transparent electrode layer 14b. The incident position 16 incident on the electrode layer 14a and the emission position 17 reflected by the reflective electrode layer 14c and emitted from the first transparent electrode layer 14a to the optical semiconductor layer 11 are shifted by the diffusion distance 18 in the second direction. be able to. As described above, the incident position 16 and the reflection position 17 from the optical semiconductor layer 11 to the second electrode 14 can be shifted by the diffusion distance 18 in the second direction, so that the light reaching the end face of the optical semiconductor layer 11 can be reduced. The amount of light emitted from the end face of the optical semiconductor layer 11 can be increased. As a result, the light emitted from the light emitting element 1 can be diffused in the second direction, and the light distribution characteristics of the light emitting element 1 can be improved.

  On the other hand, in the configuration of the light emitting element in which the refractive index of the second transparent electrode layer is smaller than the refractive index of the first transparent electrode layer, the light passing from the first transparent electrode layer to the second transparent electrode layer is second. Since the critical angle at the interface between the transparent electrode layer and the first transparent electrode layer becomes small, total reflection is likely to occur at the interface between the first transparent electrode layer and the second transparent electrode layer. As a result, it becomes difficult to effectively shift the diffusion distance in the second direction of the optical semiconductor layer.

  Furthermore, it is preferable to use a transparent conductive material containing the same component in both the first transparent electrode layer 14a and the second transparent electrode layer 14b.

  When the first transparent electrode layer 14a and the second transparent electrode layer 14b are made of, for example, indium oxide containing tin oxide, the first transparent electrode layer is adjusted by adjusting the concentrations of tin, indium, and oxygen. The refractive index of 14a can be adjusted.

  As a method for adjusting the refractive index of the first transparent electrode layer 14a, for example, the first transparent electrode layer 14a is made to have a first transparent electrode layer 14a having a lower oxygen concentration than usual and a relatively high concentration of tin and indium. The refractive index of the electrode layer 14a can be reduced. The reason why the refractive index can be reduced by reducing the oxygen concentration in this way is that the influence of tin and indium having a relatively low refractive index becomes stronger in the first transparent electrode layer 14a made of indium oxide containing tin oxide. is there.

  The indium oxide containing tin oxide whose oxygen concentration used for the first transparent electrode layer 14a is lower than usual may be set so that the oxygen concentration of normal indium oxide containing tin oxide is about 2% by mass. Specifically, when the oxygen concentration of the entire indium oxide including normal tin oxide is set to 60% by mass, for example, the oxygen concentration can be set to 58% by mass or more and 60% by mass or less.

  In addition, when the oxygen concentration of indium oxide containing tin oxide is lowered as described above, indium oxide containing tin oxide has a higher oxygen defect and thus has a higher carrier concentration and can improve conductivity. .

  Therefore, by using indium oxide containing tin oxide with a low oxygen concentration as the first transparent electrode layer 14a, the refractive index of the first transparent electrode layer 14a is reduced and the electric resistance of the first transparent electrode layer 14a is reduced. The value can be lowered, and the light emission unevenness of the light emitting element 1 can be improved. That is, by using the first transparent electrode layer 14a having a low oxygen concentration, it is possible to improve the light distribution characteristics while improving the light emission unevenness of the light emitting element 1.

<Method for manufacturing light-emitting element>
Next, an example of an embodiment of a method for manufacturing a light emitting element of the present invention will be described. 5 to 9 are cross-sectional views for explaining a method for manufacturing the light-emitting element 1, and show a portion corresponding to a cross section taken along line BB 'of the light-emitting element 1 shown in FIG.

  First, as shown in FIG. 5, the optical semiconductor layer 11 is formed on the substrate 10. The optical semiconductor layer 11 is composed of a stacked structure in which a first semiconductor layer 11a, an active layer 11b, and a second semiconductor layer 11c are sequentially stacked. Such an optical semiconductor layer 11 is grown on the substrate 10 by, for example, a metal organic chemical vapor deposition method. As another method for growing the optical semiconductor layer 11, for example, a molecular beam epitaxy method, a hydride vapor phase growth method, a pulse laser deposition method, or the like can be used.

  Next, the second electrode 14 having the first transparent electrode layer 14a, the second transparent electrode layer 14b, and the reflective electrode layer 14c is formed on the optical semiconductor layer 11 as follows.

As shown in FIG. 6, the first transparent electrode layer 14a is formed on the upper surface 11A of the optical semiconductor layer 11 using a sputtering method. Examples of such a sputtering method include a parallel plate sputtering method in which the upper surface 11A of the optical semiconductor layer 11 and the transparent conductive material face each other, and a counter sputtering method in which the upper surface 11A of the optical semiconductor layer 11 and the transparent conductive material do not face each other. Can be used. In particular, when the counter sputtering method is used when forming the first transparent electrode layer 14a, the upper surface 11A of the optical semiconductor layer 11 can be hardly damaged by sputtering, and the upper surface 11A of the optical semiconductor layer 11 can be prevented from being damaged. A state can be formed satisfactorily. As a result, the second semiconductor layer 11c constituting the upper surface 11A of the optical semiconductor layer 11 and the first transparent electrode layer 14a can be in good electrical contact.

  As the transparent conductive material of the first transparent electrode layer 14a, a transparent conductive material such as indium oxide or zinc oxide containing tin oxide having a refractive index smaller than that of the optical semiconductor layer 11 can be used. As a method for forming the first transparent electrode layer 14a, a vacuum deposition method, a CVD method, or the like can be used in addition to the sputtering method.

  As shown in FIG. 7, the second transparent electrode layer 14b is formed on the first transparent electrode layer 14b. As a method of forming the second transparent electrode layer 14b, a sputtering method ring such as a parallel plate sputtering method or a counter sputtering method can be used. As the transparent conductive material of the second transparent electrode layer 14b, a transparent conductive material such as indium oxide containing zinc oxide or zinc oxide having a refractive index larger than that of the first transparent electrode layer 14a can be used. As a method for forming the second transparent electrode layer 14b, a vacuum deposition method, a CVD method, or the like can be used in addition to the sputtering method.

  Thereafter, as shown in FIG. 8, a reflective electrode layer 14c for reflecting the light emitted from the optical semiconductor layer 11 is formed on the second transparent electrode layer 14b. As the reflective electrode layer 14c, for example, a metal material such as silver, gold, or rhodium can be used. As a method of laminating such a metal material on the second transparent electrode layer 14b, a sputtering method, a vacuum evaporation method, a CVD method, or the like can be used.

  Next, as shown in FIG. 9, the first electrode 13 is formed. As a method of forming the first electrode 13, a part of the second electrode 14 and the optical semiconductor are etched by an etching method or the like until a part of the first semiconductor layer 11 a is exposed in the depth direction from the surface of the second electrode 14. Part of layer 11 is removed. Then, a first electrode 13 electrically connected to the first semiconductor layer 11a is formed on the exposed first semiconductor layer 11a by a vacuum deposition method or a sputtering method.

  As in this example, when the first transparent electrode layer 14a and the second transparent electrode layer 14b are stacked by sputtering, the first transparent electrode layer 14a is formed by counter sputtering and the second transparent electrode layer 14b is formed by parallel plate sputtering. It is preferable to form each by a method. By forming the first transparent electrode layer 14a and the second transparent electrode layer 14b in this manner, productivity can be improved while maintaining the state of the upper surface 11A of the optical semiconductor layer 11.

  On the other hand, when the first transparent electrode layer 14a and the second transparent electrode layer 14b are formed only by the counter sputtering method, the film formation rate of the transparent electrode layer by the counter sputtering method is slower than the parallel plate sputtering method. It may be difficult to improve the performance.

  Further, as the first transparent electrode layer 14a and the second transparent electrode layer 14b, for example, when indium oxide containing tin oxide is used, as a method of reducing the oxygen concentration of the first transparent electrode layer 14a, a forming atmosphere or a transparent What is necessary is just to change the material composition of an electrode layer.

  As a method for reducing the oxygen concentration by changing the formation atmosphere of the first transparent electrode layer 14a and the second transparent electrode layer 14b, the first transparent electrode layer 14a is formed in an atmosphere of argon and nitrogen gas, then the second A method of forming the transparent electrode layer 14b in an atmosphere of argon gas and oxygen gas can be used. Specifically, when the first transparent electrode layer 14a and the second transparent electrode layer 14b are formed by the parallel plate sputtering method, after the first transparent electrode layer 14a is formed in a nitrogen gas atmosphere, the nitrogen gas atmosphere is changed to oxygen gas. The second transparent electrode layer 14b may be formed in place of the atmosphere.

Further, the first transparent electrode layer 14a and the second transparent electrode layer 14b may be formed by different forming methods. At that time, as a method for lowering the oxygen concentration of the first transparent electrode layer 14a, for example, after the first transparent electrode layer 14a is formed by a vacuum vapor deposition method with little oxygen in the atmosphere, the second transparent electrode layer 14b is formed by a sputtering method. The formation method of the 1st transparent electrode layer 14a and the 2nd transparent electrode layer 14b may be changed by forming.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light emitting apparatus 3 Wiring conductor 4 Mounting base | substrate 4a 1st sheet | seat 4b 2nd sheet | seat 5 Base | substrate recessed part 6 Mounting surface 7 Leading surface 8 Joining electrode 9 Mold resin
10 Board
11 Optical semiconductor layer
11a First semiconductor layer
11b Active layer
11c Second semiconductor layer
12 Pair of electrodes
13 First electrode (the other electrode)
14 Second electrode (one electrode)
14a First transparent electrode layer
14b Second transparent electrode layer
14c Reflective electrode layer
15 Virtual perpendicular
16 Incident position
17 Output position
18 Diffusion distance

Claims (4)

An optical semiconductor layer formed by laminating a plurality of semiconductor layers;
A pair of electrodes for applying a voltage to the optical semiconductor layer and causing the optical semiconductor layer to emit light,
The pair of electrodes has one electrode that reflects light emitted from the optical semiconductor layer, and the one electrode is provided on the optical semiconductor layer and is the uppermost layer constituting the optical semiconductor layer. A first transparent electrode layer having a refractive index lower than that of the semiconductor layer; a second transparent electrode layer having a refractive index higher than that of the first transparent electrode layer provided on the first transparent electrode layer; A light emitting device comprising: a reflective electrode layer provided on a transparent electrode layer that reflects light transmitted through the second transparent electrode layer toward the optical semiconductor layer.   2. The light emitting device according to claim 1, wherein the second transparent electrode layer has a refractive index smaller than that of the uppermost semiconductor layer constituting the optical semiconductor layer. The optical semiconductor layer is made of a gallium nitride-based material, and the first transparent electrode layer and the second transparent electrode layer are made of indium oxide containing tin,
The light emitting device according to claim 1 or 2, wherein the first transparent electrode layer has an oxygen concentration lower than that of the second transparent electrode layer.   The light emitting element according to claim 1, wherein the uppermost semiconductor layer constituting the optical semiconductor layer has irregularities, and the one electrode is provided so as to cover the irregularities.

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