JP2016009817A - Light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element in which emission unevenness is suppressed.SOLUTION: A light-emitting element has a first light-emitting part 1a and a second light-emitting part 1b including an n-type semiconductor layer 22 having a first region 22a and a second region 22b, an active layer 23 formed on the second region 22b so as to expose the first region 22a of the n-type semiconductor layer 22, a p-type semiconductor layer 24 formed on the active layer 23, a cathode electrode 31 connected with the first region 22a of the n-type semiconductor layer 22, and an anode electrode 32 arranged on the p-type semiconductor layer 24. The first light-emitting part 1a and second light-emitting part 1b are arranged so that the first regions 22a are arranged side by side in the first direction D1.

Description

  The present invention relates to a light emitting element made of a semiconductor material.

  A light emitting device (Light Emitting) in which a semiconductor material is stacked in a horizontal structure in which a cathode electrode and an anode electrode connected to an external power source are disposed at the top surface of the light emitting portion and a position shifted in the horizontal direction from the light emitting portion. Diode (LED) is known.

  In an LED having such a horizontal structure, it has been proposed to use an anode electrode that is elongated in the upper surface of the light emitting element in order to improve light emission unevenness (Patent Document 1).

JP 2007-281426 A

  However, even when a light emitting element as described in Patent Document 1 is used, there is a possibility that unevenness of light emission occurs due to a portion where current is concentrated. Therefore, there is a demand for a light-emitting element with less light emission unevenness.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a light-emitting element with less light emission unevenness.

  A light emitting device according to an embodiment of the present invention includes a first conductive semiconductor layer having a first region and a second region, and the second region so as to expose the first region of the first conductive semiconductor layer. An active layer formed on the region, a second conductive semiconductor layer formed on the active layer, a first electrode connected to the first region of the first conductive semiconductor layer, and the second A first light-emitting unit and a second light-emitting unit each including a second electrode connected to the conductive semiconductor layer, wherein the first light-emitting unit and the second light-emitting unit are mutually in the first direction. The regions are arranged in the first direction so that the regions are adjacent to each other.

  According to the light emitting element of the present invention, it is possible to provide a device with reduced light emission unevenness.

(A) is a top view which shows an example of embodiment of the light emitting element of this invention. (B) is a schematic sectional drawing along the Ib-Ib line | wire of Fig.1 (a). It is a principal part top view which shows the modification of the light emitting element shown in FIG. It is a principal part top view which shows the modification of the light emitting element shown in FIG. It is a principal part top view which shows the modification of the light emitting element shown in FIG. (A)-(c) is a principal part top view which shows the modification of the light emitting element shown in FIG. 1, respectively. (A)-(c) is the photograph which observed the light emission distribution of the light emitting element concerning an Example and a reference example, respectively. It is a diagram which shows the relationship of the emitted light intensity with respect to the applied electric current of the light emitting element concerning an Example and a reference example.

  Hereinafter, examples of embodiments of the light-emitting element of the present invention will be described with reference to the drawings. In addition, the following examples illustrate the embodiments of the method for manufacturing a light-emitting element of the present invention, and the present invention is not limited to these embodiments.

  A light emitting device according to an embodiment of the present invention includes a first conductive semiconductor layer, an active layer, a second conductive type layer, a first electrode connected to the first conductive semiconductor layer, and a first electrode connected to the second semiconductor layer. A plurality of light emitting units including two electrodes are provided.

  Here, the first conductivity type and the second conductivity type may be either p-type or n-type, respectively, but in the following example, the first conductivity type is n-type and the second conductivity type is p-type. . Thus, the first electrode is connected to the n-type semiconductor layer and functions as a cathode electrode, and the second electrode is connected to the p-type semiconductor layer and functions as an anode electrode. Hereinafter, in order to clarify the respective functions, the first conductive semiconductor layer is an n-type semiconductor layer, the second conductive semiconductor layer is a p-type semiconductor layer, the first electrode is a cathode electrode, and the second electrode is an anode electrode. explain.

  A light-emitting element 1 shown in FIGS. 1A and 1B includes a first light-emitting unit 1 a and a second light-emitting unit 1 b formed on a substrate 10. The first light emitting unit 1 a and the second light emitting unit 1 b are connected to the n-type semiconductor layer 22, the n-type semiconductor layer 22, the active layer 23, and the p-type semiconductor layer 24 that are sequentially stacked on the substrate 10. The cathode electrode 31 and the anode electrode 32 disposed on the p-type semiconductor layer 24 are included.

  The cathode electrode 31 is electrically connected to the cathode electrode pad 11 formed on the substrate 10. The anode electrode 32 is electrically connected to the anode electrode pad 12 formed on the substrate 10. When a voltage is applied from an external power source through the cathode electrode pad 11 and the anode electrode pad 12, the active layer 23 emits light. Here, the light extraction surface is on the p-type semiconductor layer 24 side, which is the upward direction in FIG.

  Here, the n-type semiconductor layer 22 of the first light emitting unit 1a and the second light emitting unit 1b is divided into a first region 22a and a second region 22b. The first region 22a is exposed with no other semiconductor layer formed on its upper surface, and the second region 22b has other semiconductor layers (23, 24) formed on its upper surface. In other words, the n-type semiconductor layer 22 includes a first region 22a exposed from the active layer 23 and the p-type semiconductor layer 24 and a second region 22b overlapping the active layer 23 and the p-type semiconductor layer 24 in a top view. Have. The anode electrode 32 has a linear configuration extending in the direction of the first region 22a in plan view.

  The first light emitting unit 1a and the second light emitting unit 1b are arranged side by side so that the first regions 22a are adjacent to each other.

  By arranging in this way, it is possible to suppress light emission unevenness as a whole of one light emitting element 1 constituted by the first light emitting unit 1a and the second light emitting unit 1b. Hereinafter, the mechanism will be described in detail. Here, “light emission unevenness” means that the light emission appears non-uniform when viewed from the light extraction surface side, for example, having a dark part where the light emission intensity is lower than others. “Improving light emission unevenness” means that the above-described dark portion ratio is reduced and light emission approaches uniformly.

Conventionally, in a light emitting element having a horizontal structure, it has been considered that the cause of unevenness in light emission is non-uniform current diffusion. Based on this, the inventors made the shape of the anode electrode a shape that does not have a bent portion that causes current concentration, or the shape of a cross-section or cross so as to be evenly connected to the entire surface of the p-type semiconductor layer. Although various studies were made on the shape of a (cross), etc., the light emission unevenness was not reduced. Further, even when a current diffusion layer for diffusing the current from the anode electrode in the plane direction is formed below the anode electrode, the light emission unevenness was not reduced. As a result of earnest execution based on these examination results, the inventors have found that the light emission unevenness of the light emitting element is caused by the length of the anode electrode. That is, no matter what kind of contrivance is added to the layer structure of the light emitting element and the electrode structure of the anode electrode, the current passes through the anode electrode having a lower electric resistance than the p-type semiconductor layer, and becomes the cathode electrode only at the tip of the anode electrode. It flowed toward the semiconductor layers 22, 23, and 24, and only the relevant part was considered to emit light. Therefore, in order to effectively use the area of the active layer, it is necessary to bring the tip of the anode electrode closer to the cathode electrode side and to shorten the distance of the anode electrode extending over the semiconductor layers 22, 23, 24. I found out. For this purpose, it has been found useful to divide the light emitting element.

  According to the light emitting element 1 shown in FIG. 1, one light emitting element is divided into a plurality of parts. Specifically, it is divided into two light emitting portions 1a and 1b, and the proportion of the area that is effectively utilized out of the total area of the active layer 23 is about twice that in the case where it is not divided, so that the proportion of the dark portion And uneven emission can be reduced.

  Furthermore, in the light emitting element 1 shown in FIG. 1, of the two light emitting portions 1 a and 1 b, the first region 22 a where the active layer 23 is not formed is adjacent along the first direction which is the arrangement direction. Two light emitting portions 1a and 1b are arranged. In such a configuration, in the two light emitting units 1a and 1b, the closest distance between the cathode electrodes 31 is shorter than the closest distance between the anode electrodes 32.

  With this configuration, light emission is collected toward the center in the arrangement direction. Since portions of the individual active layers 23 that contribute to light emission can be gathered closer to the central portion of the light emitting element 1, the light emission intensity can be maintained even in the central portion of the light emitting element 1.

  As described above, the light-emitting element 1 reduces unevenness in light emission, and particularly reduces the drop in light emission intensity at the center of the element. By adopting such a configuration, it is possible to cope with an increase in luminance and area of the light emitting element 1.

  Hereinafter, the configuration of each part will be described in detail.

(Substrate 10)
The substrate 10 is not particularly limited as long as it can hold the first light emitting unit 1a and the second light emitting unit 1b. Various insulating boards, wiring boards, printed boards and the like can also be used. In that case, what is necessary is just to comprise the semiconductor layer which comprises the 1st light emission part 1a arrange | positioned on it and the 2nd light emission part 1b, for example by bonding an epi film etc.

  In the case where the semiconductor layers (22, 23, 24) constituting the first light emitting unit 1a and the second light emitting unit 1b are formed by epitaxial growth on the substrate 10, the substrate 10 is made of a material system of the semiconductor layer grown on the substrate 10 Can be selected as appropriate. For example, when growing a nitride-based semiconductor material, a sapphire substrate, a zinc oxide substrate, a gallium nitride substrate, an aluminum nitride substrate, or the like can be used as the substrate 10. In the case of growing a GaAs-based semiconductor material, a GaAs substrate, a Si substrate, or the like can be used. In FIG. 1, a case where a GaAs-based semiconductor layer (22, 23, 24) is formed using a Si substrate as the substrate 10 will be described as an example.

(Semiconductor layer constituting light emitting part 1a and light emitting part 1b)
A plurality of semiconductor layers are stacked on the upper surface 10 a of the substrate 10. These semiconductor layers can be formed by epitaxial growth on the substrate 10 using, for example, a MOCVD (Metal-organic Chemical Vapor Deposition) apparatus.

  First, a buffer layer 21 is provided on the upper surface of the substrate 10 to buffer a difference in lattice constant between the substrate 10 and a semiconductor layer (an n-type contact layer 221 described later in this example) stacked on the upper surface of the substrate 10. Is formed. The buffer layer 21 reduces lattice defects such as lattice strain generated between the substrate 10 and the semiconductor layer by buffering the difference in lattice constant between the substrate 10 and the semiconductor layer formed on the upper surface 10a of the substrate 10. As a result, it has a function of reducing lattice defects or crystal defects in the entire semiconductor layer formed on the upper surface 10 a of the substrate 10.

  The buffer layer 21 of this example is made of gallium arsenide (GaAs) containing no impurities and has a thickness of about 2 to 3 μm. If the difference in lattice constant between the substrate 10 and the semiconductor layer stacked on the upper surface of the substrate 10 is not large, the buffer layer 21 can be omitted.

An n-type contact layer 221 is formed on the upper surface of the buffer layer 21. The n-type contact layer 221 is formed by doping gallium arsenide (GaAs) with n-type impurities such as silicon (Si) or selenium (Se), and the doping concentration is 1 × 10 ¹⁶ to 1 × 10 ²⁰ atoms / cm ^3. The thickness is about 0.8 to 1 μm.

In this example, silicon (Si) is doped as an n-type impurity at a doping concentration of 1 × 10 ¹⁸ to 2 × 10 ¹⁸ atoms / cm ³ . A part of the upper surface of the n-type contact layer 221 is exposed, and the exposed part is connected to an external power source via the cathode electrode 31. The n-type contact layer 221 has a function of reducing contact resistance with the cathode electrode 31 connected to the n-type contact layer 221.

  The cathode electrode 31 is formed with a thickness of about 0.5 to 5 μm using, for example, a gold (Au) antimony (Sb) alloy, a gold (Au) germanium (Ge) alloy, or a Ni-based alloy. At the same time, since it is disposed on the insulating layer 208 formed so as to cover the upper surface of the n-type contact layer 221 from the upper surface of the substrate 10, it is electrically connected to the semiconductor layers other than the substrate 10 and the n-type contact layer 221. Is insulated.

The insulating layer 208 is formed of, for example, an inorganic insulating film such as silicon nitride (SiN _x ) or silicon oxide (SiO ₂ ), an organic insulating film such as polyimide, and the thickness thereof is set to about 0.1 to 1 μm. Yes.

An n-type cladding layer 222 is formed on the upper surface of the n-type contact layer 221, and has a function of confining electrons in an active layer 23 described later. The n-type cladding layer 222 is formed by doping aluminum gallium arsenide (AlGaAs) with silicon (Si) or selenium (Se), which is an n-type impurity, and has a doping concentration of 1 × 10 ¹⁶ to 1 × 10 ²⁰ atoms / cm. The thickness is about ³ , and the thickness is about 0.2 to 0.5 μm. In this example, silicon (Si) is doped as an n-type impurity at a doping concentration of 1 × 10 ^{17 to} 5 × 10 ¹⁷ atoms / cm ³ .

The n-type contact layer 221 and the n-type cladding layer 222 are combined to form an n-type semiconductor layer 22. The n-type semiconductor layer 22 has a first region 22a and a second region 22b in plan view. Of these, the active layer 23 is formed on the second region 22b. In this example, the n-type cladding layer 222 is formed only in the second region 22b. That is, the n-type semiconductor layer 22 has a terrace-shaped step, the terrace portion is the first region 22a, and the cathode electrode 31 is formed along the direction in which the first region 22a extends. Has been.

  An active layer 23 is formed on the upper surface of the n-type cladding layer 222, and functions as a light emitting layer that emits light when carriers such as electrons and holes are concentrated and recombined. The active layer 23 is made of aluminum gallium arsenide (AlGaAs) containing no impurities and has a thickness of about 0.1 to 0.5 μm. The active layer 23 of this example is a layer that does not contain impurities, but it may be a p-type active layer containing p-type impurities or an n-type active layer containing n-type impurities. It is sufficient that the band gap 23 is smaller than the band gap of the n-type cladding layer 222 and the p-type cladding layer 241 described later.

  The shape of the active layer 23 in the planar direction is rectangular, and the ratio of the lengths of two sides orthogonal to each other is set to 0.75 to 1.25. By adopting such a shape, if the current spreads isotropically, the area of the active layer 23 can be effectively utilized. For example, the two sides constituting the planar shape of the active layer 23 may be about 35 to 45 μm and about 40 to 60 μm.

A p-type cladding layer 241 is formed on the upper surface of the active layer 23 and has a function of confining holes in the active layer 23. The p-type cladding layer 241 is formed by doping aluminum gallium arsenide (AlGaAs) with p-type impurities such as zinc (Zn), magnesium (Mg), or carbon (C), and the doping concentration is 1 × 10 ¹⁶ to 1 ×. The thickness is about 10 ²⁰ atoms / cm ³ and the thickness is about 0.2 to 0.5 μm. In this example, magnesium (Mg) is doped as a p-type impurity at a doping concentration of 1 × 10 ^{19 to} 5 × 10 ²⁰ atoms / cm ³ .

A p-type contact layer 242 is formed on the upper surface of the p-type cladding layer 241. In the p-type contact layer 242, aluminum gallium arsenide (AlGaAs) is doped with p-type impurities such as zinc (Zn), magnesium (Mg), or carbon (C), and the doping concentration is 1 × 10 ¹⁶ to 1 ×. The thickness is about 10 ²⁰ atoms / cm ³ and the thickness is about 0.2 to 0.5 μm.

  The p-type contact layer 242 is electrically connected to an external power source via the anode electrode 32. The p-type contact layer 242 has a function of reducing contact resistance with the anode electrode 32 connected to the p-type contact layer 242.

  The p-type cladding layer 241 and the p-type contact layer 242 are combined into a p-type semiconductor layer 24.

  Further, a cap layer having a function of preventing oxidation of the p-type contact layer 242 may be formed on the upper surface of the p-type contact layer 242. The cap layer may be formed of, for example, gallium arsenide (GaAs) that does not contain impurities, and the thickness thereof may be about 0.01 to 0.03 μm.

  The anode electrode 32 is not particularly limited as long as it is a conductive material, for example, but a combination of gold (Au) or aluminum (Al) and nickel (Ni), chromium (Cr) or titanium (Ti) as an adhesion layer. It is formed of AuNi, AuCr, AuTi, or AlCr alloy, and the thickness thereof is about 0.5 to 5 μm, and is formed so as to cover the upper surface of the p-type contact layer 242 from the upper surface 10 a of the substrate 10. Since the semiconductor layer is disposed on the insulating layer 208, it is electrically insulated from the semiconductor layer other than the substrate 10 and the p-type contact layer 242.

  In this example, the anode electrode 32 extends linearly from the end of the second region 22b opposite to the first region 22a toward the first region 22a in plan view. The length of the line needs to be long enough to cross the second region 22b so as to approach the first region 22a. When the line width is increased, the ratio of covering the light extraction surface is increased. In order to effectively use the active layer 23, the active layer 23 is provided so as to extend in the vicinity of the width center.

  In the light emitting portions 1a and 1b configured by such a stack of semiconductor layers, the active layer 23 emits light by applying a bias between the cathode electrode 31 and the anode electrode 32, and functions as a light source of light. To do.

(Arrangement of light emitting unit 1a and light emitting unit 1b)
The light emitting unit 1a and the light emitting unit 1b having the above-described configuration are arranged so that the first regions 22a face each other in the first direction D1 (the vertical direction in FIG. 1A). That is, the 1st area | region 22a of the light emission part 1a and the light emission part 1b is arrange | positioned so that it may adjoin along the 1st direction D1 which is an arrangement direction.

(Electrode pads 11, 12)
A cathode electrode pad 11 and an anode electrode pad 12 are formed on the upper surface 10 a of the substrate 10. The cathode electrode pad 11 is electrically connected to the cathode electrode 31 of the first light emitting unit 1a and the second light emitting unit 1b, and the anode electrode pad 12 is connected to the anode electrode 32 of the first light emitting unit 1a and the second light emitting unit 1b. Electrically connected. That is, the cathode electrodes 31 and the anode electrodes 32 of the first light emitting unit 1a and the second light emitting unit 1b are connected to the same electrode pads 11 and 12, respectively. Thereby, it becomes possible to operate the 1st light emission part 1a and the 2nd light emission part 1b simultaneously.

  Such electrode pads 11 and 12 are made of, for example, AuNi, AuCr, AuTi, or a combination of gold (Au) or aluminum (Al) and nickel (Ni), chromium (Cr), or titanium (Ti) as an adhesion layer. It is made of an AlCr alloy or the like and has a thickness of about 0.5 to 5 μm. When the substrate 10 has conductivity, it is electrically insulated from the substrate 10 by being disposed on the insulating layer 208 formed on the upper surface 10a of the substrate 10.

  As described above, by connecting the first light emitting unit 1a and the second light emitting unit 1b to the electrode pads 11 and 12, the first light emitting unit 1a and the second light emitting unit 1b are connected in parallel. By connecting in parallel, an increase in junction temperature can be suppressed, and the applied current can be increased. Thereby, the light emitting element 1 which has high light emission intensity can be provided.

  Such a light-emitting element 1 is incorporated in a sensor device, the detection body is irradiated with light from the light-emitting element 1, the reflected light or transmitted light is received by the light-receiving element, and the position and type of the detection body according to the amount of received light , Size, etc. can be sensed. Moreover, it can incorporate in a light irradiation apparatus and shall be able to irradiate light uniformly with respect to a large area.

<Modification 1>
FIG. 2 shows a top view of the main part of the light emitting element 1A. The light emitting element 1A shown in FIG. 2 is different in that the light emitting element 1 includes a p-type semiconductor layer 22A and a cathode electrode 31A. Since the other configuration is the same as that of the light emitting element 1, only different portions will be described and redundant description will be omitted.

In the light emitting element 1A, the first light emitting unit 1a and the second light emitting unit 1b share a common cathode electrode 31A. More specifically, a continuous buffer layer 21 and an n-type contact layer 221 common to the first light emitting unit 1 a and the second light emitting unit 1 b are provided on the substrate 10.

  By setting it as such a structure, the active layer 23 of the 1st light emission part 1a and the active layer 23 of the 2nd light emission part 1b can be arrange | positioned closely. Thereby, the fall of the emitted light intensity in the element center part of 1 A of light emitting elements can be suppressed.

<Modification 2>
FIG. 3 shows a top view of the main part of the light emitting element 1B. The light emitting element 1B shown in FIG. 3 is different in that the combination of the first light emitting unit 1a and the second light emitting unit 1b constituting the light emitting element 1 is arranged in a second direction D2 orthogonal to the first direction D1. Only different points will be described below.

  In the light emitting element 1B, a combination of the first light emitting unit 1a and the second light emitting unit 1b is arranged in a second direction D2 orthogonal to the first direction D1. That is, four light emitting portions are arranged in a matrix. By arranging in this way, the cathode electrodes 31 of each other are gathered on the center side of the structure formed by the assembly of the active layers of the four light emitting parts, and the anode electrodes 32 are gathered outside the structure. .

  With such a configuration, it is possible to provide the light-emitting element 1B in which the occurrence of unevenness in light emission is reduced and the decrease in light emission intensity at the center of the element is suppressed even when the light-emitting area is increased. In this example, two rows are arranged in the second direction, but three or more rows may be arranged.

<Modification 3>
FIG. 4 shows a top view of the main part of the light emitting element 1C. The light emitting element 1C shown in FIG. 4 is different in that the light emitting element 1B includes a p-type semiconductor layer 22C and a cathode electrode 31C. Only different points will be described below.

  In the light emitting element 1C, the two first light emitting units 1a and the two second light emitting units 1b share the cathode electrode 31C with each other. More specifically, a continuous buffer layer 21 and an n-type contact layer 221 common to the first light emitting unit 1 a and the second light emitting unit 1 b are provided on the substrate 10.

  With such a configuration, the active layers 23 of the four light emitting units (two first light emitting units 1a and two second light emitting units 1b) can be arranged close to each other. Thereby, the fall of the emitted light intensity in the element center part of the light emitting element 1C can be suppressed.

  Further, in this example, the first region 22a is also provided between the two first light emitting units 1a and the two second light emitting units 1b along the second direction, and the cathode electrode 31C2 is provided thereon. Yes. That is, the cathode electrode 31C has a shape along the cross shape between the four light emitting portions. Thereby, in addition to the current of the individual light emitting portions 1a and 1b flowing from the tip of the anode electrode 32C toward the cathode electrode 31C1 in the first direction to emit light (broken line), the anode electrode 32C to the cathode electrode 31C1 in the second direction. A current flows through each of the light emitting units 1a and 1b to emit light (dotted line). As a result, it is possible to increase the proportion of the active layers 23 of the individual light emitting portions 1a and 1b in which the current flows and is effectively used, and it is possible to provide the light emitting element 1C with less light emission unevenness.

<Modification 4>
In the above-described example, the anode electrode 32 is described as an example of a linear shape, but is not limited to this example. For example, it may be an electrode on a layer made of a light-transmitting material such as ITO, which is formed on the entire upper surface of the p-type semiconductor layer 24, or as shown in a schematic diagram of a main part in FIG. In plan view, the main portion 32Da extending from the end of the second region 22b opposite to the first region 22a toward the first region 22a and the shape of the first region 22a from the tip of the main portion 32Da It may include the extending portion 32Db extending in this manner. In other words, the extending portion 32Db is formed along a shape in which the first region 22a and the second region 22b are opposed to each other. In this example, it is T-shaped.

  By forming the anode electrode 32D in this way, current diffusion is also promoted in the second direction. In the figure, the cathode electrode 31 is not shown.

  In addition, the planar shape of the first region 22a and the second region 22b has been described as an example in which rectangular shapes are arranged in the first direction, but as shown in FIG. The rectangular 1st area | region 22a may be located in one corner of the parts 1a and 1b.

  Further, as shown in FIG. 5C, an L-shaped first region 22a along two continuous sides of the rectangular second region 22b may be used. In this case, the cathode electrode 31D is positioned in the first direction D1 and the second direction D2, and the distance between the cathode electrode 31D and the main portion 32Da of the anode electrode 32D can be kept substantially constant. Can be used effectively. Thereby, the light emitting element which suppressed light emission nonuniformity can be provided.

  Furthermore, the anode electrode 32D may include an extending part 32Db and a branch part 32Dc extending from the middle of the main part 32Da toward the first region 22a located in the second direction. When the length of the main portion 32Da extending in the first direction D1 is long, the branch portion 32Dc can diffuse current to the active layer 23 at a position away from the first region 22a located in the first direction D1. it can.

  Based on the light emitting element 1B shown in FIG. 3, the light emitting element which concerns on an Example was manufactured. Specifically, a GaAs-based semiconductor layer was laminated on a substrate 10 made of a Si single crystal substrate to form four light emitting portions 1a and 1b. The planar shape of the active layer 23 of each light emitting section 1a, 1b is rectangular, the length of the side parallel to the first direction is 55 μm, and the length of the side parallel to the second direction is 40 μm.

  The anode electrode 32 has a linear shape extending in the first direction from the center in the second direction of each active layer in plan view.

  Next, as Comparative Example 1, a light-emitting element including one light-emitting portion having the same element area as the light-emitting element of the example was manufactured. In the light-emitting element of the comparative example, the planar shape of the active layer was rectangular, the length of the side parallel to the first direction was 150 μm, and the length of the side parallel to the second direction was 80 μm. The anode electrode had a linear shape extending from the central portion in the second direction of each active layer in the first direction in plan view.

  Further, as Comparative Example 2, in the configuration of the light emitting device according to the example, the arrangement of the four light emitting portions is arranged such that the second region 22b is gathered at the center of the device and the first region 22a is located at the outer peripheral portion of the device. A light-emitting element arranged in the above manner was manufactured. In addition, the shape of each light emission part, the shape of the anode electrode, etc. were made the same as the light emitting element of an Example.

  Next, as a reference example, a light-emitting element including a light-emitting portion in which the element area of the light-emitting element of the comparative example was divided into two in the second direction was manufactured. In the light emitting device of the reference example, the planar shape of the active layer was rectangular, the length of the side parallel to the first direction was 150 μm, and the length of the side parallel to the second direction was 40 μm. The anode electrode had a linear shape extending from the central portion in the second direction of each active layer in the first direction in plan view.

As a second reference example, a light emitting device having a cross-shaped anode electrode instead of the anode electrode of the first reference example was manufactured.

  A current was applied to each of the light emitting elements described above, and the state of light emission from the upper surface side, which was the light extraction surface, was confirmed. A part of the result is shown in FIG. As shown in FIG. 6A, the light emitting device according to the example has a dark portion in a region where the first regions 22a of the respective light emitting portions are gathered in the central portion, but the entire active layer emits light. It could be confirmed. As a result, when the emission spectrum of the entire device was confirmed, it was confirmed that the emission intensity was maintained over the entire device area, although there was a drop in the center.

  On the other hand, the light emitting element of Comparative Example 1 emits light at the center in the second direction at one end on the first region side (cathode electrode side) in the first direction, and most of the other is a dark part. Confirmed that. In the light-emitting element of Comparative Example 2, the light emission ratio of each active layer in each light-emitting portion was a constant amount, but the outer frame of the portion that emits light with respect to the outer peripheral frame of the element when the first region is located on the outer peripheral side Was small. Further, in each active layer, light emission is distributed in the direction toward the outer peripheral side of the device, and a dark portion is generated in the central portion of the device. The dark part in the center part of the element is added with the dark part caused by the gap between the light emitting parts and the anode electrode wiring in addition to the dark part caused by the light emission distribution. As a result, the dark part exceeding the area of the dark part in the element center part of the light emitting element according to Example 1 was generated.

  Further, it was confirmed that the light emitting element of the reference example emitted light only at one end on the first region side (cathode electrode side) in the first direction as shown in FIG. 6B. However, compared with the light emitting element of Comparative Example 1, the spread of light in the second direction was increased, and it was confirmed that it was preferable to divide the light emitting portion.

  Furthermore, as shown in FIG. 6C, it was confirmed that the light emitting device of the second reference example had the same light emission distribution as the light emitting device of the reference example even when the shape of the anode electrode was changed. Thereby, it was confirmed that only the tip region on the first region side (cathode electrode side) of the anode electrode contributes to light emission, and the electrode shape on the side away from the first region does not affect the light emission characteristics.

  From the above, it was confirmed that the light emission intensity could be maintained over the entire area of the element only by dividing the light emitting portion and arranging the first region 22a side by side on the element center side.

  Further, a DC current was passed through the light emitting element of the example and the light emitting element of the reference example, and the relationship between the current value and the light emission intensity was measured. As a result, as shown in FIG. 7, the light emitting intensity of the light emitting element of the example increases with an increase in current, but it is confirmed that the light emitting intensity of the light emitting element of the reference example decreases when it exceeds a certain current value. It was done. In the light emitting element of the example, it is considered that the increase in the junction temperature can be suppressed by increasing the number of the light emitting units arranged in parallel, so that the emission intensity is not reduced. From this, it was confirmed that by increasing the number of light emitting units arranged in parallel, it is possible to increase the current value that can be input, and as a result, it is possible to form a light emitting element with high light emission intensity.

DESCRIPTION OF SYMBOLS 1 Light emitting element 1a 1st light emission part 1b 2nd light emission part 10 Board | substrate 11 Cathode electrode pad 12 Anode electrode pad 21 Buffer layer 22 N-type semiconductor layer (1st conductivity type semiconductor layer)
22a 1st area | region 22b 2nd area | region 23 Active layer 24 p-type semiconductor layer (2nd conductivity type semiconductor layer)
31 Cathode electrode (first electrode)
32 Anode electrode (second electrode)
32a main part

Claims (6)

A first conductive semiconductor layer having a first region and a second region; an active layer formed on the second region so as to expose the first region of the first conductive semiconductor layer; A second conductivity type semiconductor layer formed on the layer; a first electrode connected to the first region of the first conductivity type semiconductor layer; a second electrode disposed on the second conductivity type semiconductor layer; A first light emitting unit and a second light emitting unit,
The light emitting device, wherein the first light emitting unit and the second light emitting unit are arranged in the first direction such that the first regions are adjacent to each other in the first direction.   The first light emitting unit and the second light emitting unit are arranged such that a closest distance between the second electrodes is larger than a closest distance between the first electrodes. The light emitting element of description.   The light emitting element of Claim 1 or 2 which arranges the combination of a said 1st light emission part and a said 2nd light emission part along with the 2nd direction orthogonal to the said 1st direction.   4. The light emitting device according to claim 1, wherein the first electrode of the first light emitting unit and the first electrode of the second light emitting unit are shared.   The planar shape of the second region is a rectangular shape, and the ratio of the lengths of two orthogonal directions is 0.75 to 1.25. Light emitting element.   The said 2nd electrode contains the main part extended toward the said 1st area | region by planar view, and the extension part extended so that the shape of the said 1st area | region may be extended from the front-end | tip part of the said main part. The light emitting device according to any one of 5.