JP2016115920A - Light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the impact of sheet resistance increase of a transparent electrode.SOLUTION: A current block layer 18 is formed between a p layer 13 and a transparent electrode 14. The area 14a of the transparent electrode 14 on the current block layer 18 has a sheet resistance higher than that in the area of other transparent electrode 14. Plane pattern of the current block layer 18 is a circular pattern including a contact part 16c. A straight line passing an arbitrary position in the contact part 16c of the p electrode 16, and whose distance from that position to the contact part 17c of the n electrode 17 is shortest is L. The center O' of the width of the current block layer 18 in the direction of the straight line L is farther from the contact part 17c of the n electrode 17 than the center O of the width of the contact part 16c of the p electrode 16 in the direction of the straight line L. Consequently, driving voltage rise due to sheet resistance increase of the area 14a of the transparent electrode 14 can be reduced.SELECTED DRAWING: Figure 3.A

Description

  The present invention relates to a light emitting device made of a group III nitride semiconductor. In particular, the present invention relates to a device having characteristics in the position and the planar pattern of the current blocking layer.

  In a light-emitting element made of a group III nitride semiconductor, a technique for preventing light absorption by the p-electrode and improving the light-emitting efficiency by preventing the light-emitting layer at the position overlapping the p-electrode in plan view from being emitted is known. Yes.

  In Patent Documents 1 and 2, a current blocking layer made of a translucent insulator is provided between the p layer and the transparent electrode and immediately below the p pad electrode, and the light emitting layer immediately below the p pad electrode emits light. In addition, there is described a light-emitting element made of a group III nitride semiconductor in which light emission efficiency is improved by reflecting light at the interface between the p layer and the current blocking layer.

JP 2008-192710 A JP 2010-232649 A

  When the current blocking layer is provided on the p layer, a transparent electrode is provided so as to cover the p layer and the current blocking layer, and a p electrode is provided on the transparent electrode above the p layer. The current is diffused outside the region where the current blocking layer is provided by the transparent electrode. Therefore, the sheet resistance of the transparent electrode needs to be lowered.

However, depending on the combination of the selected material for the current blocking layer and the transparent electrode, the configuration of the current blocking layer and the transparent electrode, the processing conditions after formation, the transparent electrode on the current blocking layer has a high sheet resistance after its formation, and light emission There has been a problem that the drive voltage of the element increases. For example, a case where a material mainly containing indium oxide is used as the transparent electrode and a material containing oxygen as a constituent element such as SiO ₂ or SiON is used as the current blocking layer.

  Therefore, an object of the present invention is to reduce the influence of an increase in sheet resistance of a transparent electrode located on a current blocking layer. In particular, an object is to reduce an increase in driving voltage of the light emitting element. Another object is to increase the uniformity of light emission of the light emitting element.

  The present invention includes a semiconductor layer made of a group III nitride semiconductor and laminated in the order of an n layer, a light emitting layer, and a p layer, a transparent electrode made of a transparent conductive oxide located on the p layer, and a transparent electrode One or a plurality of p-side current injection portions located in contact with each other, one or a plurality of n-side current injection portions connected to the n layer, and between the p layer and the transparent electrode and below the p-side current injection portion And a current blocking layer made of a group III nitride semiconductor, and the current blocking layer is provided in a region including the p-side current injection portion in a plan view, L is a straight line that passes through an arbitrary position of the current injection portion and has the shortest distance from the position to the n-side current injection portion, O is the center of the width of the p-side current injection portion in the straight L direction, and is in the straight L direction. The center of the width of the current blocking layer is O ′, and the center O and the center in the straight line L direction O 'is not overlap, a light emitting element, characterized in that.

If the center O ′ of the width of the current blocking layer in the straight line L direction is located farther from the n-side current injection part in the straight line L direction than the center O of the width of the p-side current injection part in the straight line L direction, An increase in driving voltage due to an increase in sheet resistance of the transparent electrode located on the blocking layer can be reduced.
If the center O ′ of the width of the current blocking layer in the straight line L direction is closer to the n-side current injection part in the straight line L direction than the center O of the width of the p-side current injection part in the straight line L direction. The uniformity of light emission can be improved by controlling the flow of electrons in the device.
Further, the above two cases may be mixed in one chip with respect to the displacement direction of the width O of the current blocking layer relative to the center O of the width of the p-side current injection portion.
One configuration example is that when there are a plurality of different values regarding the distance between the p-type current injection portion and the n-type current injection portion closest to the p-type current injection portion, the maximum distance and the minimum distance When a half of the sum is taken as the average distance, the center O ′ of the width of the current blocking layer in the straight line L direction for the p-type current injection portion where the distance exists between the maximum distance and the average distance is The arrangement is a position farther from the n-side current injection portion in the straight line L direction than the center O of the width of the p-side current injection portion in the straight line L direction. In another configuration example, for a p-type current injection portion where a distance exists between the minimum distance and the average distance, the center O ′ of the width of the current blocking layer in the straight line L direction is the straight line L direction. The arrangement is such that it is positioned closer to the n-side current injection portion in the straight line L direction than the center O of the width of the p-side current injection portion. Moreover, it is good also as a structure which combines both the structural examples.
With this configuration, more uniform light emission can be realized on the surface.
Furthermore, in another configuration example, each light emission distribution is more uniform than the light emission distribution on the surface when the center O of the p-type current injection portion and the center O ′ of the current blocking layer are matched. The position deviation and the direction of the center O ′ of the current blocking layer with respect to the center O of the p-side current injection portion with respect to the p-type current insertion portion are determined. Irrespective of the electrode structure, more uniform light emission can be obtained on the surface of one chip. Further, as a result of making the current density uniform, the driving voltage can be reduced as compared with the case where the center O ′ and the center O are matched.

  The planar pattern of the current blocking layer may be any pattern, but all or part of the blocking layer outline including the p-side current injection part of the planar pattern of the current blocking layer may be the plane of the p-side current injection part. It is desirable to enlarge the similarity of the line outside the injection part of the pattern. This is from the point of uniformity of light emission and ease of production.

  As a method of making the width center O in the straight line L direction of the p-side current injection portion different from the width center O ′ in the straight line L direction of the current blocking layer in the straight line L direction, there is a current blocking layer. In addition to the method of shifting the position of the plane pattern itself, the following method may be used. That is, the blocking layer outline of the part including the p-side current injection part is formed by cutting out a part of a shape obtained by enlarging the injection part outline with the center of gravity of the injection part outline as the center of gravity. That is, instead of shifting the position of the planar pattern, the shape of the planar pattern is changed.

  The present invention is particularly effective when the sheet resistance of the region on the current blocking layer of the transparent electrode is higher than that of the region on the p layer, but can also be applied to other cases.

Any transparent conductive oxide can be used for the transparent electrode, but indium oxide-based materials such as IZO (zinc-doped indium oxide) and ITO (indium tin oxide) are preferable in terms of ease of production and cost. .

For the current blocking layer, a material made of an arbitrary insulator can be used, but it is preferable to use an arbitrary material made of a transparent insulator containing oxygen as a constituent element in terms of light extraction. Here, “transparent” means having a high transmittance with respect to the emission wavelength of the light emitting element. SiO ₂ , SiON, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , Nb ₂ O ₅ , etc. can be used, and silicon compounds are particularly desirable.

  The present invention is particularly effective for a light-emitting element having the following configuration.

  An insulating film positioned on the transparent electrode and having a hole for injecting current into the transparent electrode, and a p-electrode positioned on the insulating film, and the p-electrode is in contact with the transparent electrode through the hole A light-emitting element characterized in that a portion of the p electrode that contacts the transparent electrode inside the hole is a p-side current injection portion.

  An intermediate electrode positioned in contact with the transparent electrode, an insulating film positioned on the transparent electrode and the intermediate electrode, and having a hole for injecting a current into the intermediate electrode; a p-electrode positioned on the insulating film; The p-electrode is in contact with the intermediate electrode through a hole, and the intermediate electrode serves as a p-side current injection portion.

A p-electrode positioned on and in contact with the transparent electrode, and the p-electrode has a connection part electrically connected to the outside of the element, and a wiring-like part extending in a wiring shape from the connection part, A light-emitting element, wherein the p-electrode is a p-side current injection part.
In all the above-mentioned inventions, it is desirable that the minimum value of the positional deviation between the center O ′ of the current blocking layer and the center O of the p-side current injection portion is 2 μm. The maximum position deviation is determined by maximally displacing the center O ′ with respect to the center O on the condition that the orthogonal projection of the p-type current injection portion on the current blocking layer exists in the plane of the current blocking layer. It is the position deviation at the time.

  According to the present invention, even if the sheet resistance of the transparent electrode on the current blocking layer increases, it can be made less susceptible to the influence, and the light emission efficiency can be improved or the uniformity of light emission can be increased. .

2 is a cross-sectional view illustrating a configuration of a light-emitting element according to Example 1. FIG. The top view which looked at the light emitting element of Example 1 from upper direction. 6 is a cross-sectional view illustrating a configuration of a light-emitting element according to a modification of Example 1. FIG. FIG. The top view of the contact part 16c part in A. FIG. The figure which expanded the contact part 16c part in the top view of FIG. The figure which showed the modification of the plane pattern of the electric current blocking layer. The figure which showed the principle of this invention typically. FIG. 6 shows a manufacturing process of the light-emitting element of Example 1. Sectional drawing which showed the structure of the light emitting element of Example 2. FIG. The figure which expanded the contact part 16c part of the light emitting element of Example 2. FIG. Sectional drawing which showed the structure of the light emitting element of Example 3. FIG. The top view which looked at the light emitting element of Example 3 from upper direction. The top view which looked at the light emitting element of Example 4 from upper direction. Sectional drawing which showed the structure of the light emitting element of Example 4. FIG. The top view which looked at the light emitting element of Example 5 from upper direction. The top view which looked at the light emitting element of Example 6 from upper direction. The top view which looked at the light emitting element of Example 7 from upper direction. The top view which looked at the light emitting element of Example 8 from upper direction.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to the examples.

  FIG. 1 is a cross-sectional view showing the configuration of one chip of a light-emitting element made of a group III nitride semiconductor of Example 1. FIG. 2 is a plan view of the light-emitting element made of a group III nitride semiconductor of Example 1 as viewed from above. 1 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the light-emitting element made of a group III nitride semiconductor of Example 1 is a rectangular face-up element in plan view. The chip has a rectangular shape with a short side piece of 200 μm and a long side of 800 μm. The short side may be formed in a range of 200 to 300 μm, and the long side may be formed in a range of 700 to 800 μm.

  As shown in FIG. 1, the light-emitting element made of a group III nitride semiconductor of Example 1 includes a substrate 10, an n layer 11 positioned on the substrate 10 via a buffer layer (not shown), and an n layer 11. It has a light emitting layer 12 located and a p layer 13 located on the light emitting layer 12. The n layer 11, the light emitting layer 12, and the p layer 13 are made of a group III nitride semiconductor. Further, a groove reaching the n layer 11 from the surface side of the p layer 13 is formed, and the n layer 11 is exposed on the bottom surface of the groove. Moreover, it has the transparent electrode 14 located on the p layer 13, and the insulating film 15 located continuously on the transparent electrode 14 and the n layer 11 exposed to the groove bottom face. A p-electrode 16 and an n-electrode 17 are separately provided on the insulating film 15. Further, a current blocking layer 18 is provided in a predetermined region between the p layer 13 and the transparent electrode 14. Hereinafter, each configuration will be described in more detail.

  The substrate 10 is a sapphire substrate having an uneven surface processing (not shown) on the surface on the n layer 11 side. Concavity and convexity processing is provided to improve light extraction efficiency. In addition to sapphire, the substrate 10 may be made of any material capable of crystal growth of a group III nitride semiconductor. For example, SiC, Si, ZnO or the like.

The n layer 11 has a structure in which an n-type contact layer, an n-type ESD layer, and an n-type SL layer are stacked in this order from the substrate 10 side. The n-type contact layer is a layer in contact with the n-electrode 17. The n-type contact layer is made of n-GaN having a Si concentration of 1 × 10 ¹⁸ / cm ³ or more. It is possible to reduce the contact resistance of the n-electrode 17 by configuring the n-type contact layer with a plurality of layers having different carrier concentrations. The n-type ESD layer is an electrostatic withstand voltage layer for preventing electrostatic breakdown of the element. The n-type ESD layer has a stacked structure of non-doped GaN and Si-doped n-GaN. The n-type SL layer is an n-type superlattice layer having a superlattice structure in which a unit of a structure in which InGaN, GaN, and n-GaN are stacked in order is repeatedly stacked. The n-type SL layer is a layer for relaxing stress applied to the light emitting layer 12.

  The light emitting layer 12 has an MQW structure in which a well layer made of InGaN and a barrier layer made of AlGaN are repeatedly stacked. A protective layer for preventing evaporation of In may be provided between the well layer and the barrier layer.

The p layer 13 has a structure in which a p-type cladding layer and a p-type contact layer are stacked in this order from the light emitting layer 12 side. The p-type cladding layer is a layer for preventing electrons from diffusing to the p-type contact layer side. The p-type cladding layer has a structure in which p-InGaN and p-AlGaN are sequentially stacked, and this is repeatedly stacked a plurality of times. The p-type contact layer is a layer provided for the p-electrode 16 to make good contact with the p-layer 13. The p-type contact layer is made of p-GaN having an Mg concentration of 1 × 10 ¹⁹ to 1 × 10 ²² / cm ³ and a thickness of 100 to 1000 mm.

  Note that the configurations of the n layer 11, the light emitting layer 12, and the p layer 13 are not limited to those described above, and any configuration conventionally used for a light emitting element made of a group III nitride semiconductor should be adopted. Can do.

  The transparent electrode 14 is made of IZO (zinc-doped indium oxide). In addition, indium oxide-based materials such as ITO (indium tin oxide) and other transparent conductive oxides can be used. The transparent electrode 14 is continuously formed on the p layer 13 and the current blocking layer 18. Therefore, the transparent electrode 14 is formed in a film-like shape that undulates at the top of the current blocking layer 18. A fine uneven shape may be provided on the surface of the transparent electrode 14 to improve the light extraction efficiency.

  Of the transparent electrode 14, a region 14 a located on the current blocking layer 18 has a higher sheet resistance than other regions of the transparent electrode 14. This is mainly because the region of the transparent electrode 14 located on the p-layer 13 is located on the current blocking layer 18 while the sheet resistance does not change much even after the heat treatment in the electrode formation process. The region 14a is caused by an increase in sheet resistance after the heat treatment. Further, as will be described later, the increase in the resistance of the region 14 a located in contact with the current blocking layer 18 is also caused by the influence of the irregularities on the surface of the current blocking layer 18.

The insulating film 15 is formed so as to cover from the surface of the n layer 11 exposed on the bottom surface of the groove to the surface of the transparent electrode 14. Insulating film 15 is made of SiO _2. In addition to SiO ₂ , SiN, Al ₂ O ₃ , TiO ₂ or the like can be used. In addition, a hole 21 p for the p electrode 16 and a hole 21 n for the n electrode 17 are provided at predetermined positions of the insulating film 15 and penetrate the insulating film 15. The hole 21p is filled with a wiring portion 16b of the p electrode 16 described later, and the hole 21n is filled with a wiring portion 17b of the n electrode 17. The contact portion between the transparent electrode 14 and the wiring portion 16b filled in the hole 21p is a contact portion 16c (intermediate electrode) of the p electrode 16, and the wiring shape filled in the n-type contact layer of the n layer 11 and the hole 21n. A contact portion with the portion 17 b is a contact portion 17 c of the n-electrode 17.

  As shown in FIG. 2, a reflective film 19 is provided in the insulating film 15 in a region (except for the contact portions 16c and 17c) that overlaps the p-electrode 16 and the n-electrode 17 in plan view. . Since the reflective film 19 is in the insulating film 15, it is electrically insulated and migration is prevented. This reflective film 19 is provided to suppress light absorption by the p-electrode 16 and the n-electrode 17 by reflecting light traveling toward the p-electrode 16 and the n-electrode 17, thereby improving luminous efficiency. .

  The reflective film 19 is made of a material having a higher reflectance than the material of the p-electrode 16 and the n-electrode 17 such as Al, Ag, Al alloy, or Ag alloy. The reflective film 19 may be a single layer or a multilayer. In the case of a multilayer, Al alloy / Ti, Ag alloy / Al, Ag alloy / Ti, Al / Ag / Al, Ag alloy / Ni, or the like can be used. Here, the symbol “/” means a laminate, and A / B means a laminate structure in which A is deposited and then B is deposited. Hereinafter, “/” is used in the same meaning in the description of the material. In order to improve the adhesion between the reflective film 19 and the insulating film 15, a thin film such as Ti, Cr, or Al may be provided between the reflective film 19 and the insulating film 15.

In addition, a dielectric multilayer film can be employed as the reflective film 19. The dielectric multilayer film is a multilayer film in which a low refractive index material and a high refractive index material are alternately laminated, and each optical film thickness is designed to be ¼ of the emission wavelength. As the low refractive index material, SiO ₂ , MgF ₂ , or the like can be used, and as the high refractive index material, SiN, TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , Nb ₂ O _5, or the like can be used. . In order to improve the reflectivity of the dielectric multilayer film, it is desirable that the difference in refractive index between the low refractive index material and the high refractive index material is larger. Moreover, it is desirable that the number of stacked pairs is large, and it is desirable that the number is 5 pairs or more. However, the number of stacked pairs is preferably 30 pairs or less so that the total thickness of the dielectric multilayer film is increased and no problems occur in the manufacturing process.

  As shown in FIG. 2, the p electrode 16 includes a wire bonding portion 16a, a wiring portion 16b, and a contact portion 16c (a p-side current injection portion and an intermediate electrode of the present invention). 4 is an enlarged view of the contact portion 16c in the plan view of FIG. FIG. 4 is a plan view showing the orthogonal projection relationship of the wiring-like portion 16b, the hole 21p, the contact portion 16c, and the current blocking layer 18, as viewed from above, and the insulating film 15 and the transparent electrode 14 do not exist ( Expressed as transparent). Hereinafter, FIG. B, same as in FIGS. The contact portion 16c is made of Ni / Au / Al, and the wire bonding portion 16a and the wiring portion 16b are made of Ti / Au / Al.

  The wire bonding portion 16a is a circular region located on the insulating film 15, and is a region connected to the wire. The wiring portion 16b is a wiring-like portion located on the insulating film 15 and extending from the wire bonding portion 16a. The wiring portion 16b diffuses current in the surface direction by forming a wiring shape. Further, the wiring portion 16 b is also formed inside the hole 21 p provided in the insulating film 15. The contact portion 16 c is a plurality of dot-like circular regions provided on the transparent electrode 14. Further, the contact portion 16 c is connected to the wiring portion 16 b through a hole 21 p provided in the insulating film 15. The contact portion 16c is provided in order for the p-electrode 16 and the transparent electrode 14 to make good contact. Note that the hole 21p and the contact portion 16c do not have to have the same shape in plan view, and may be any shape as long as the hole 21p is included in the contact portion 16c in plan view.

  As shown in FIG. 2, the wire bonding portion 16a is located near the center of one short side. Two linear wiring portions 16b extend from the wire bonding portion 16a. The wiring portion 16b has a linear part extending along the long side in the vicinity of one long side, and a linear part extending along the long side in the vicinity of the other long side. . The straight portion is branched in the direction perpendicular to the surface by the hole 21p, and is connected to the circular contact portion 16c at the branch end. From the viewpoint of current diffusivity, it is desirable to match the center of the hole 21p with the center of the contact portion 16c.

  The n electrode 17 is composed of a wire bonding portion 17a, a wiring portion 17b, and a contact portion 17c (the n-side current injection portion of the present invention), as in the case of the p electrode 16. It is the same as the case of. As shown in FIG. 2, the wire bonding portion 17a is located in the vicinity of the center of the end opposite to the side where the wire bonding portion 16a is located. A single linear wiring portion 17b extends in parallel to the long side from the wire bonding portion 17a, and is located at the center of the short side between the two linear shapes of the wiring portion 16b. Yes. Further, the wire bonding portion 17a and the wiring portion 17b of the n electrode 17 are made of the same material as the wire bonding portion 16a and the wiring portion 16b of the p electrode 16, and the contact portion 17c is made of the same material as the contact portion 16c. ing.

  In addition, FIG. A and FIG. FIG. 3 is a plan view of the wiring-like portion 16b and the hole 21p of the p-electrode 16 in FIG. As shown in B, the wiring portion 16b may be in direct contact with and connected to the transparent electrode 14 without providing the contact portion 16c. In this case, the contact portion (contact portion 16d) of the wiring portion 16b with the transparent electrode 14 corresponds to the p-side current injection portion of the present invention. Similarly, the wiring portion 17b may be directly in contact with and connected to the n layer 11 without providing the contact portion 17c. In this case, the contact portion (contact portion 17d) of the wiring portion 17b with the contact layer of the n layer 11 corresponds to the n-side current injection portion of the present invention. FIG. A configuration in the case where both of the contact portions 16c and 17c are not provided in A is illustrated. Further, the p-electrode 16 and the n-electrode 17 are not necessarily configured to have the wiring portions 16b and 17b.

  The region excluding the wire bonding portion 16a of the p electrode 16 and the wire bonding portion 17a of the n electrode 17 is formed so as to cover a protective film (not shown). This is to prevent a short circuit of current.

  The current blocking layer 18 blocks the current in the region so that the region of the light emitting layer 12 that overlaps the current blocking layer 18 in a plan view (a region orthogonally projected onto the light emitting layer 12 of the current blocking layer 18) is prevented from being emitted. To. Further, the total reflection at the interface between the p-layer 13 and the current blocking layer 18 prevents light from being directed to the upper portion of the current blocking layer 18. With these two actions, light absorption / shielding by the p-electrode 16 located above the current blocking layer 18 can be suppressed, and the light emission efficiency can be improved.

  The current blocking layer 18 is shown in FIGS. B, as shown in FIG. 4, provided on the p layer 13 in a region including the contact portions 16 c and 16 d in plan view. That is, the current blocking layer 18 includes the contact portions 16c and 16d in plan view. Thus, by providing the current blocking layer 18 in a region wider than the contact parts 16c and 16d, light absorption and shielding by the contact parts 16c and 16d are effectively suppressed. In the present embodiment, the current blocking layer 18 is not provided in other portions of the p-electrode 16, that is, in the orthogonal projection regions below the wire bonding portion 16 a and the wiring-like portion 16 b. However, the current blocking layer 18 may be provided in the orthogonal projection region of the wire bonding portion 16a or the wiring portion 16b.

  In addition, FIGS. Like B, the current blocking layer 18 has a circular shape including the contact portions 16c and 16d in a plan view, and the centers of the contact portions 16c and 16d do not coincide with the center of the current blocking layer 18. In such a case, all of the blocking layer outlines including the p-side current injection portions 16c and 16d of the planar pattern of the current blocking layer 18 are the outer lines of the injection portion of the planar pattern of the p-side current injection portions 16c and 16d. This corresponds to the case of similar enlargement.

The method of not matching the centers of the warps is as follows. In the plan view, the contact portion that passes through an arbitrary position (for example, the center of the circle in the plan view) of the p-electrode 16 and is the closest to the contact portion 16c among the many contact portions 17c of the n-electrode 17 A straight line passing through an arbitrary position of 17c (for example, the center of a circle in plan view) is defined as L. The center of the width of the contact portion 16c of the p-electrode 16 in the straight line L direction is O, and the center of the width of the current blocking layer 18 in the straight line L direction is O ′. The width is the length of a line segment that the straight line L is cut off by both ends of the contact portion 16c or the current blocking layer 18. At this time, the center O ′ is farther from the contact portion 17c of the n-electrode 17 than the center O. However, the positional deviation of the center O ′ with respect to the center O is a deviation within a range in which the current blocking layer 18 includes the contact portion 16c.
Further, since the straight line L does not necessarily pass through the center (circular center) of the current blocking layer 18 in plan view, the center O ′ of the width of the current blocking layer 18 in the direction of the straight line L is It does not necessarily coincide with the center (circular center) in plan view. Similarly, since the straight line L may not be set so as to pass through the circular center of the contact portion 16c and the circular center of the contact portion 17c, the center O of the width in the straight line L direction of the contact portion 16c is the contact portion 16c. It does not necessarily coincide with the center (circular center) in plan view.
In Example 1, the center of the circular pattern of the current blocking layer 18 is positioned away from the contact part 17c in the short side direction of the light emitting element with respect to the center of the circular pattern of the contact part 16c. To satisfy the relationship between the centers O and O ′.

  1 and 4, as an example, the straight line L is a straight line connecting the circular center of the contact portion 16c of the p electrode 16 and the circular center of the contact portion 17c of the n electrode 17, and the contact portion 16c in the direction of the straight line L is shown. In this case, the center O of the width is made to coincide with the center of the circle in plan view of the actual contact portion 16c. The cross-sectional view of FIG. 1 is a cross-sectional view taken along the line AA along the straight line L of FIG.

  In the first embodiment, the planar pattern of the current blocking layer 18 is circular and the similar enlarged pattern of the contact portion 16c. However, the planar shape of the current blocking layer 18 is not necessarily similar. For example, if the plane pattern of the current blocking layer 18 is a similar enlarged pattern in which the center (centroid) in plan view coincides with the center (center of gravity) of the contact portion 16c, and a part of the pattern is cut away, In the straight line L direction, the width center O ′ of the current blocking layer 18 in the straight line L direction and the width center O of the contact portion 16 c in the straight line L direction can be easily made different. That is, the center O ′ and the center O ′ are made different from each other by a simple means of providing a notch in the pattern of the current blocking layer 18 having a similar enlarged pattern with the same center. To avoid overlapping).

  An example is shown in FIG. FIG. 5 shows a case where the straight line L passes through the circular center of the contact portion 16c (the center O of the width in the direction of the straight line L coincides with the circular center). As a planar pattern of the current blocking layer 18, the center is the same as the center of the contact portion 16c and the diameter is larger than that of the contact portion 16c, and a part of the circle near the contact portion 17c of the n-electrode 17 is formed. It is a notch. Thus, by the notch, the center O ′ of the width of the current blocking layer 18 in the straight line L direction can be shifted from the center O of the width of the contact part 16 c in a direction away from the contact part 17 c in the straight line L direction. In such a case, a part of the blocking layer outline including the p-side current injection part 16c of the planar pattern of the current blocking layer 18 is a similar enlargement of the injection part external line of the planar pattern of the p-side current injection part 16c. This is the case.

In addition to SiO ₂ , a transparent insulator containing oxygen as a constituent element, particularly a silicon compound can be used for the current blocking layer 18. For example, metal oxide, metal oxynitride, etc., specifically, SiON, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , Nb ₂ O ₅ , etc. can be used. In addition, various insulators such as nitrides such as AlN and SiN, carbides such as SiC, and fluorides can be used. However, in the case of an insulator containing oxygen as a constituent element, the region 14a of the transparent electrode 14 located on the current blocking layer 18 tends to have a higher sheet resistance than other regions of the transparent electrode 14, and the effect of the present invention can be achieved. Easy to get. A single layer or a multilayer of these materials may be used, and any of a single crystal, a polycrystal, and an amorphous state may be used. Moreover, it is good also as a dielectric multilayer film which laminated | stacked two types of films | membranes from which an optical film thickness is 1/4 wavelength and a refractive index differ alternately. When such a dielectric multilayer film is used, the light toward the p-electrode 16 is reduced due to the improvement in reflectance, and the light absorption by the p-electrode 16 is reduced, so that the light emission efficiency can be further improved. .

  The current blocking layer 18 is desirably made of an arbitrary material having a refractive index smaller than that of the p layer 13. The light extraction efficiency can be improved by totally reflecting light at the interface between the p layer 13 and the current blocking layer 18 and not directing the light toward the p electrode 16 side. When the p layer 13 is composed of a plurality of layers, the refractive index should be lower than that of the layer closest to the current blocking layer 18. In the case where the p layer 13 is a laminate of a p-type cladding layer and a p-type contact layer in order from the substrate side, any material lower than that of the p-type contact layer may be used.

  Further, the current blocking layer 18 may have a shape whose side surface has an inclination of 5 to 60 ° with respect to the surface of the p layer 13. That is, the shape in a cross section perpendicular to the element is preferably trapezoidal (tapered). By setting it as such a shape, disconnection of the transparent electrode 14, the p electrode 16, a wire, etc. can be prevented. A more desirable inclination angle is 5 to 30 °. When the side surface of the current blocking layer 18 has an inclination as described above, the width of the current blocking layer 18 in the straight line L direction is the width at the lower surface of the current blocking layer 18 (the surface on the p layer 13 side). The center of the width is O ′. When the side surface of the contact portion 16c is inclined, the width of the contact portion 16c in the direction of the straight line L is the width on the lower surface of the contact portion 16c (the surface on the side in contact with the transparent electrode 14). Let O be the center.

  The thickness of the current blocking layer 18 is desirably thicker than λ / (4n) (λ is the emission wavelength, and n is the refractive index of the current blocking layer 18). By making it thicker than λ / (4n), the insulation and the reflection function can be made sufficient. More desirably, it is 100 nm or more. The thickness of the current blocking layer 18 is preferably less than 1500 nm. If it is thicker than this, there is a possibility that the wire, the transparent electrode 14, the p-electrode 16, or the like may be broken due to a step caused by the thickness. More desirably, it is 500 nm or less.

  As described above, in the light-emitting element composed of the group III nitride semiconductor of Example 1, the current blocking layer 18 has a pattern including the contact portion 16c in plan view, and passes through an arbitrary position in the contact portion 16c. The straight line with the shortest distance from the position to the contact part 17c of the n electrode 17 is L, and the center O ′ of the width of the current blocking layer 18 in the direction of the straight line L is The current blocking layer 18 is provided so as to be farther from the contact portion 17c of the n electrode 17 than the center O of the width. Thereby, there is an advantage that an increase in drive voltage is suppressed. The reason will be described below.

When the transparent electrode 14 made of IZO is formed on the current blocking layer 18 made of SiO ₂ and then subjected to heat treatment, the sheet resistance of the region 14a located on the current blocking layer 18 in the transparent electrode 14 is higher than before the heat treatment. Become. This is considered to be a phenomenon that occurs because oxygen contained in the current blocking layer 18 diffuses during heat treatment and is taken into the transparent electrode 14, and oxygen in the transparent electrode 14 becomes excessive and carriers are reduced.

  Alternatively, the sheet resistance of the region 14a of the transparent electrode 14 may be increased due to unevenness on the surface of the current blocking layer 18. That is, since the transparent electrode 14 is formed along the unevenness on the surface of the current blocking layer 18, if the unevenness is large, the thickness of the transparent electrode 14 on the current blocking layer 18 varies, resulting in unevenness or breakage. As a result, the sheet resistance of the region 14a of the transparent electrode 14 becomes higher than that of other regions.

  When the center O of the width of the contact portion 16c in the direction of the straight line L and the center O ′ of the width of the current blocking layer 18 in the direction of the straight line L are made to coincide, as shown in FIG. The current flowing from the portion 16c to the region 14a of the transparent electrode 14 in the horizontal direction and going to the p layer 13 becomes difficult to flow because the distance flowing through the region 14a becomes longer. As a result, the drive voltage increases.

  Therefore, in the first embodiment, the center O ′ of the width of the current blocking layer 18 in the straight line L direction is positioned farther from the contact part 17 c than the center O of the width of the contact part 16 c in the straight line L direction. As a result, as shown in FIG. 6A, the region 14a of the transparent electrode 14 flows from the contact portion 16c to the contact portion 17c side in the horizontal direction, and the current flowing through the region 14a in the current toward the p layer 13 is shortened. . Therefore, it becomes difficult to be influenced by the region 14a having a high sheet resistance, and the current easily flows. Therefore, an increase in drive voltage can be suppressed.

  In order to further reduce the increase in drive voltage, the smaller the distance between α and β in FIGS. That is, the width of the current blocking layer 18 in the straight line L direction is 2 × d1, and the current injection part in the straight line L direction (the contact portion 16c in the first embodiment shown in FIGS. 1, 4 and 5, FIG. 3. In the modification shown in B, the width of the hole 21p) is 2 × d2, and the distance between α and β is preferably smaller than d1 to d2 (see FIGS. 1 to 6). The case where the distance between α and β is equal to d1-d2 is the case where the center O coincides with the center O ′, and the case where the distance between α and β is smaller than d1-d2 is the center O ′ as the center O. In this case, the position is farther from the contact portion 16c (see FIG. 6). The width of the contact portion 16c of the p-electrode 16 is desirably ½ or less of the diameter of the contact portion 16c, and most preferably, α and β are matched. Here, α is a point closer to the contact portion 17c of the n-electrode 17 out of two points where the straight line L and the outer periphery of the current blocking layer 18 intersect. Β is the outer circumference of the straight line L and the current injection portion (the contact portion 16c in the first embodiment shown in FIGS. 1, 4 and 5 and the hole 21p in the modification shown in FIGS. 3.A and 3.B). Among the two points where the crossing points, the point on the side close to the contact portion 17c of the n-electrode 17 is.

  Next, the manufacturing method of the light emitting element which consists of a group III nitride semiconductor of Example 1 is demonstrated with reference to FIG.

  First, a substrate 10 made of sapphire having a concavo-convex process on its surface was prepared, and heat treatment was performed in a hydrogen atmosphere to remove impurities adhering to the surface.

  Next, an n layer 11, a light emitting layer 12, and a p layer 13 were sequentially stacked on the substrate 10 by MOCVD (FIG. 7A). Source gases include TMG (trimethylgallium) as a Ga source, TMA (trimethylaluminum) as an Al source, TMI (trimethylindium) as an In source, ammonia as an N source, biscyclopentadienylmagnesium as a p-type dopant gas, n Silane was used as the type dopant gas. Hydrogen and nitrogen were used as the carrier gas.

Next, the current blocking layer 18 was formed on the p layer 13. The current blocking layer 18 was patterned by photolithography and wet etching after forming a SiO ₂ film by vapor deposition or CVD. The pattern may be formed by photolithography, sputtering or vapor deposition, or lift-off. The current blocking layer 18 is a circular pattern including a circular plane pattern of the contact portion 16c of the p electrode 16 to be formed later. Further, as a planar pattern of the current blocking layer 18, from the contact portion 17c of the n electrode 17 formed later in the short side direction of the light emitting element with respect to the circular center of the contact portion 16c. The pattern was kept away.

  Next, the transparent electrode 14 was formed in a predetermined region on the p layer 13 and the current blocking layer 18 (FIG. 7B). The transparent electrode 14 was formed by photolithography and wet etching after forming an IZO film by sputtering. Thereafter, heat treatment was performed in vacuum at 650 ° C. for 5 minutes, and the transparent electrode 14 was baked to reduce resistance.

  Next, a predetermined region on the surface of the p layer 13 was dry etched to form a groove, and the n layer 11 was exposed on the bottom surface of the groove. Then, a contact portion 16c of the p electrode 16 was formed in a predetermined region on the transparent electrode 14, and a contact portion 17c of the n electrode 17 was formed in a predetermined region on the n layer 11 exposed at the bottom of the groove (see FIG. 7C). The contact portions 16c and 17c were patterned by photolithography, vapor deposition, and lift-off. The contact parts 16c and 17c may be formed separately, but when the contact parts 16c and 17c are made of the same material, the contact parts 16c and 17c may be formed simultaneously. The manufacturing process can be simplified and the manufacturing cost can be reduced. Thereafter, heat treatment was performed at 550 ° C. for 5 minutes in a reduced pressure oxygen atmosphere of 15 Pa to alloy the contact portions 16c and 17c.

Here, the sheet resistance of the transparent electrode 14 in the region 14a located on the current blocking layer 18 in the transparent electrode 14 is increased by the heat treatment of baking the transparent electrode 14 or alloying the contact portions 16c and 17c. The sheet resistance increases by about 10 to 20 times in the heat treatment for firing the transparent electrode 14 and about 600 to 800 times in the heat treatment for alloying. This is considered because IZO which is the transparent electrode 14 has taken in oxygen due to SiO ₂ which is the current blocking layer 18. Therefore, when a transparent conductive oxide is used as the transparent electrode 14 and a transparent insulator containing oxygen as a constituent element is used as the current blocking layer 18, the same phenomenon occurs and the sheet resistance of the transparent electrode 14 increases. It is thought that it will end.

  Next, an insulating film 15 is formed so as to cover the entire upper surface. Subsequently, a reflective film 19 was formed on the entire surface, and a predetermined pattern of the insulating film 15 and the reflective film 19 was formed by photolithography and etching. Thereafter, the insulating film 15 was further formed on the entire surface, and predetermined regions (regions corresponding to the upper portions of the contact portions 16c and 17c) of the insulating film 15 were dry-etched to form holes 21p and 21n penetrating the insulating film 15. Contact portions 16c and 17c are exposed on the bottom surfaces of the holes 21p and 21n, respectively. Then, the wire bonding part 16a and the wiring part 16b of the p electrode 16, and the wire bonding part 17a and the wiring part 17b of the n electrode 17 were formed on the insulating film 15 by photolithography, vapor deposition, and lift-off. Here, the wiring portions 16b and 17b are formed so as to also fill the insides of the holes 21p and 21n, and the wiring portions 16b, the contact portions 16c, and the wiring portions 17b are formed inside the holes 21p and 21n, respectively. And the contact portion 17c are connected. The reflective film 19 is inside the insulating film 15 in a lower region including orthogonal projections of the wire bonding portion 16a and the wiring portion 16b of the p electrode 16 and the wire bonding portion 17a and the wiring portion 17b of the n electrode 17. Exists.

  Next, a protective film was formed on the entire surface excluding the wire bonding portions 16a and 17a by CVD, photolithography, and dry etching. By the above method, the group III nitride semiconductor light emitting device of Example 1 shown in FIG. 1 was produced.

  FIG. 8 is a cross-sectional view of a light-emitting element made of a group III nitride semiconductor of Example 2. The light emitting device of Example 2 is a current blocking layer 28 in place of the current blocking layer 18 in the light emitting device of Example 1, and the current blocking layer 28 changes the plane pattern of the current blocking layer 18 of Example 1. It is a thing. Other configurations are the same as those of the light-emitting element of Example 1.

  FIG. 9 is an enlarged view of the contact portion 16c when the light emitting device of Example 2 is viewed from above. As shown in FIGS. 8 and 9, the current blocking layer 28 has a circular planar pattern, and is formed in a pattern including the contact portion 16 c in plan view. Further, when the straight line L is defined in the same manner as in the first embodiment, the center O ′ of the width of the current blocking layer 28 in the direction of the straight line L is more contacted than the center O of the width of the contact portion 16c in the straight line L direction. The pattern is a position close to the portion 17c.

  When the planar pattern of the current blocking layer 28 is set in this way, the region 14a of the transparent electrode 14 flows from the contact portion 16c in the horizontal direction toward the contact portion 17c, and the current flowing toward the p layer 13 has a long distance flowing through the region 14a. It becomes difficult to flow. On the other hand, the current flowing toward the side opposite to the contact portion 17c side is easy to flow because the distance flowing through the region 14a is shortened. For this reason, the current on the contact portion 17c side, which has been flowing a lot in the past, is reduced, the current on the side opposite to the contact portion 17c side which has been small in the prior art is increased, the current distribution is equalized, and the light emission uniformity is improved.

  In order to make the current distribution uniform, the larger the distance between α and β in FIGS. That is, when d1 and d2 are defined as in the first embodiment, it is better that the distance between α and β is larger than d1 and d2 (see FIGS. 8 and 9). The case where the distance between α and β is larger than d1−d2 is the case where the center O ′ is positioned closer to the contact portion 16c than the center O (see FIGS. 8 and 9). Desirably, it should be 1/2 or more of the diameter of the contact portion 16c. α and β are the same definitions as in the first embodiment.

  FIG. 10 is a cross-sectional view of a light emitting device made of a Group III nitride semiconductor of Example 3. FIG. 11 is a plan view of the light-emitting element of Example 3 as viewed from above. FIG. 10 is a cross section taken along line BB in FIG. B-B is the short side direction of the light emitting element. As shown in FIG. 10, the light emitting device of Example 3 is a rectangular face-up device in plan view. 10 and 11, the same components as those of the light emitting device of Example 1 are denoted by the same reference numerals.

  As shown in FIG. 10, the light emitting device of Example 3 is different from Example 1 in the configuration on the transparent electrode 14. The light emitting device of Example 1 has a configuration in which the insulating film 15 is provided on the transparent electrode 14 and the p electrode 16 is provided on the insulating film 15. However, in the light emitting device of Example 3, the p is directly formed on the transparent electrode 14. An electrode 36 is provided. An n electrode 37 is provided directly on the n layer 11. Further, a current blocking layer 38 is provided in place of the current blocking layer 18. The current blocking layer 38 is the same as the current blocking layer 18 except for the planar pattern.

  As shown in FIG. 11, the p-electrode 36 is provided in contact with the transparent electrode 14 and has a wire bonding portion 36a and a wiring-like portion 36b. These are the same planar patterns as the wire bonding portion 16a and the wiring-like portion 16b of Example 1, respectively. As shown in FIG. 11, the n-electrode 37 is provided in contact with the n-layer 11 and includes a wire bonding portion 37a and a wiring-like portion 37b. These are the same planar patterns as the wire bonding part 17a and the wiring part 17b of Example 1, respectively. The entire p electrode 36 corresponds to the p-side current injection portion of the present invention, and the entire n electrode 37 corresponds to the n-side current injection portion of the present invention.

  The current blocking layer 38 is provided between the p layer 13 and the transparent electrode 14. The planar pattern of the current blocking layer 38 is a pattern in which the p electrode 36 is enlarged in a similar manner, and is a pattern that includes the p electrode 36. Further, when the straight line L is defined as in the first embodiment, the center O ′ of the width of the current blocking layer 38 in the direction of the straight line L is more n electrode than the center O of the width of the p electrode 36 in the direction of the straight line L. The position is far from 37. Similarly to Example 1, the region of the transparent electrode 14 located on the current blocking layer 38 is a region 14a having a higher sheet resistance than other regions.

  As a specific example of the straight line L, a case where an intersection P between BB and the wiring portion 36b is selected as shown in FIG. 11 will be described. In this case, the shortest straight line L from the point P to the n-electrode 37 (wiring-like portion 37b) is the same as a straight line parallel to the short side of the light emitting element, that is, BB. This is because the wiring portion 36b and the wiring portion 37b are parallel to the long side direction of the light emitting element.

  When the current blocking layer 38 is formed as described above, the same effect as in the first embodiment can be obtained. That is, the center O ′ of the width of the current blocking layer 38 in the straight line L direction is farther from the wiring part 37 b of the n electrode 37 than the center O of the width of the wiring part 36 b of the p electrode 36 in the straight line L direction. Therefore, the distance flowing through the region 14a in the current flowing from the p-electrode wiring portion 36b in the horizontal direction through the region 14a of the transparent electrode 14 toward the wiring portion 37b of the n-electrode 37 and toward the p-layer 13 is as follows. Shorter. Therefore, it becomes difficult to be influenced by the region 14a having a high sheet resistance, and the current easily flows. Therefore, an increase in drive voltage can be suppressed.

  In order to further reduce the increase in drive voltage, the smaller the distance between α and β in FIG. 10, the better, as in the first embodiment. That is, when d1 and d2 are defined as in the first embodiment, it is better that the distance between α and β is smaller than d1 and d2 (see FIG. 10). Desirably, the line width of the wiring portion 36b as a contact portion is ½ or less, and most desirably, α and β are made to coincide. α and β have the same definitions as in the first embodiment.

  In Example 3, the center O ′ of the current blocking layer 38 in the straight line L direction is closer to the wiring part 37 b of the n electrode 37 than the center O of the wiring part 36 b of the p electrode 36 in the straight line L direction. If it becomes a position, the effect similar to Example 2 can be acquired. That is, the uniformity of light emission can be improved. In this case, as in the second embodiment, the larger the distance between α and β, the better. That is, the larger the distance between α and β is, the better. Desirably, it should be ½ or more of the line width of the wiring portion 36b which is a contact portion.

  In the light emitting device of Example 4, the center O ′ of the width of the current blocking layer 18 in the straight line L direction is set at the contact part 16c in the straight line L direction (the modified example of FIG. 3.A having no special contact part 16c). In Example 1, the center O ′ of the width of the current blocking layer 28 is located farther from the contact portion 17c of the n-electrode 17 than the center O of the width of the hole 21p), and the contact portion of the n-electrode 17 from the center O. This is an example in combination with Example 2 at a position close to 17c. The structure is shown in FIG. 13 which is a cross-sectional view taken along the line A2-A2 of FIGS. In the figure, the wiring portion 16b is directly joined to the transparent electrode 14 through the hole 21p without the special contact portions 16c and 17c, and the wiring portion 17b is connected to the n layer 11 through the hole 21n. In this example, the contact layer is directly bonded to the contact layer. These joint portions also function as the contact portions 16c and 17c. Therefore, the joint part between the wiring part 16b and the transparent electrode 14 and the joint part between the wiring part 17b and the contact layer of the n layer 11 are referred to as “contact part” in all the following examples.

  For the linear wiring portion 16by1 of the p electrode 16 on the line Y1, the structure of the first embodiment is used. For the linear wiring portion 16by2 of the p electrode 16 on the line Y2, the linear wiring portion 16by1 of the second embodiment is used. The structure is used. The wire-like portion 16by2 on the line Y2 is closer to the linear wire-like portion 17b (of the n-electrode 17) extending in parallel with the long side from the center of the chip short side than the wire-like portion 16by1 on the line Y1. . Therefore, the distance of the first path between the contact portion 16dy1 of the wiring portion 16by1 on the line Y1 and the contact 17d portion of the wiring portion 17b of the n electrode 17 is equal to that of the contact portion 16dy2 of the wiring portion 16by2 on the line Y2. It is longer than the distance of the second path between the contact portions 17d of the wiring portion 17d of the electrode 17. For this reason, the resistance of the first path is larger than the resistance of the second path.

Therefore, in order to realize a uniform current distribution on the surface, the center O ′ of the width of the current blocking layer 18y1 on the line Y1 is set to the center of the chip with respect to the center O of the width of the contact portion 16dy1 of the wiring portion 16by1. By moving away from the wiring-like part 17b of the part, the current path on the current blocking layer 18y1 toward the contact part 17d is shortened, and the resistance of the first path is reduced. Further, the center O ′ of the width of the current blocking layer 18y2 on the line Y2 is brought closer to the wiring portion 17b at the center of the chip with respect to the center O of the width of the contact portion 16dy2 of the wiring portion 16by2. Thereby, the resistance of the path on the current blocking layer 18y2 is increased in the second path having a low resistance. On the contrary, the resistance on the current blocking layer 18y2 in the path toward the long side of the chip on the current blocking layer 18y2 is reduced as in the second embodiment. As a result, even if the linear wiring portions 16by1 and the wiring portions 16by2 parallel to the long side of the chip are disposed asymmetrically with respect to the midpoint of the short side of the chip, the light emitting layer is formed on the surface of the chip. The current density distribution on the surface of the current flowing vertically through 12 can be made more uniform and uniform. As a result, the emission luminance can be made uniform and uniform on the surface.
In this embodiment, the special contact portions 16c and 17c shown in FIG. 1 of the first embodiment and FIG. 8 of the second embodiment may be provided.

The light-emitting element of Example 5 is an example in which the arrangement of the p-electrode wiring portions of Example 4 is asymmetric with respect to the midpoint of the chip short side in the structure of Example 3 shown in FIG.
As shown in FIG. 14, the light-emitting element of Example 5 has a center O ′ of the width in the straight line L direction (parallel to the chip short side) of the current blocking layer 38y1 extending linearly in parallel to the chip long side. Example 1 in which the wiring portion 36by1 extending linearly parallel to the long side of the chip is positioned farther from the wiring portion 37b of the n electrode 37 than the center O of the width in the straight line L direction, and the current blocking layer 38y2 This is an example in which the center O ′ of the width is combined with an example in which the center O ′ of the width of the wiring part 36by2 is closer to the wiring part 37b of the n electrode 17.

  The structure of the third embodiment is used for the linear wiring portion 36by1 of the p-electrode 36 on the line Y1. The linear wiring portion 36by2 on the line Y2 has a linear wiring portion 37b (the n-electrode 37 of the n-electrode 37) extending in parallel with the long side from the center portion of the short side of the chip than the wiring portion 36by1 on the line Y1. Close to). Therefore, the distance of the 1st path | route between the wiring-shaped part 36by1 directly aligned with the transparent electrode 14 on the line Y1 and the linear wiring-shaped part 37b directly joined to the n contact layer of the n layer 11 is on the line Y2. It is longer than the distance of the second path between the wiring part 36by2 and the wiring part 37b of the n-electrode 37. For this reason, the resistance of the first path is larger than the resistance of the second path.

  Therefore, in order to realize a uniform current distribution on the surface, the center O ′ of the width of the current blocking layer 38y1 on the line Y1 is set to the wiring shape at the center of the chip with respect to the center O of the width of the wiring portion 36by1. By moving away from the portion 37b, the path toward the wiring-shaped portion 37b on the current blocking layer 38y1 is shortened, and the resistance of the first path is reduced. Further, the center O 'of the width of the current blocking layer 38y2 on the line Y2 is brought closer to the wiring portion 37b in the center of the chip with respect to the center O of the width of the wiring portion 36by2. Thereby, in the second path having a small resistance, the resistance of the current path toward the wiring-like portion 37b of the path on the current blocking layer 38y2 is increased. Conversely, the resistance on the current blocking layer 38y2 in the current path toward the long side of the chip on the current blocking layer 38y2 is reduced as in the second embodiment. As a result, even if the linear wiring portions 36by1 and the wiring portions 36by2 parallel to the long side of the chip are arranged asymmetrically with respect to the midpoint of the short side of the chip, the light emitting layer The current density distribution on the surface of the current flowing vertically through 12 can be made more uniform and uniform. As a result, the emission luminance can be made uniform and uniform on the surface.

The light-emitting element of Example 6 has a structure in which the structures of Example 1 and Example 2 are combined in the chip long side direction.
In FIG. 15, the wiring portion 46 b of the p electrode is a distance (hereinafter referred to as “the contact portion 46 d) and the contact portion 47 d of the wiring portion 47 b of the n electrode 47 extending parallel to the long side at the center of the short side of the chip. The distance between the pn contact portions ”) is formed in a waveform such that long regions E1 and short regions E2 appear alternately in the chip long side direction. In this embodiment, the special contact portions 16c and 17c as shown in FIG. 1 are not provided, and the wiring portion 46b is directly bonded to the transparent electrode 14 through the hole 21p as shown in FIG. In this example, the wiring portion 47b is directly joined to the contact layer of the n layer 11 through the hole 21n as shown in FIG. These joint portions also function as the contact portions 16c and 17c. Therefore, the joint part between the wiring part 46b and the transparent electrode 14 is represented as contact parts 46de1 and 46de2, and the joint part between the wiring part 47b and the contact layer of the n layer 11 and the contact part 47d.

  In the region E1 where the distance between the pn contact portions is long, the structure of the first embodiment is used, and in the region E2 where the distance between the pn contact portions is short, the structure of the second embodiment is used. The first path, which is the shortest path between the contact part 46de1 of the wiring part 46b in the area E1 and the contact part 47d of the wiring part 47b, is the contact part 46de2 of the wiring part 46b and the wiring part 47b in the area E2. It is longer than the second path which is the shortest path between the contact portions 47d. For this reason, the resistance of the first path is larger than the resistance of the second path.

Therefore, in order to realize a uniform current distribution on the surface, the center O ′ of the width of the current blocking layer 18e1 in the region E1 is set to the center O of the width of the contact portion 46de1 of the wiring portion 46b. By moving away from the central wiring-like part 47b, the current path on the current blocking layer 18e1 toward the contact part 47d is shortened, and the resistance of the first path is reduced. In the region E2, the center O ′ of the width of the current blocking layer 18e2 is brought closer to the wiring portion 47b at the center of the chip with respect to the center O of the width of the contact portion de2 of the wiring portion 46b. As a result, in the second path with low resistance, the resistance of the current path on the current blocking layer 18e2 toward the contact portion 47d is increased. On the contrary, the resistance on the current blocking layer 18e2 in the path toward the long side of the chip on the current blocking layer 18e2 is reduced as in the second embodiment. As a result, the current density distribution on the surface of the chip, and hence on the surface of the current flowing vertically through the light emitting layer 12, can be made more uniform and uniform. As a result, the emission luminance can be made uniform and uniform on the surface.
In this embodiment, the special contact portions 16c and 17c shown in FIG. 1 of the first embodiment and FIG. 8 of the second embodiment may be provided.

  In the present embodiment, the structure of the first embodiment is used for the four ends of the wiring portion of the p electrode, and the structure of the second embodiment is used for other regions. As shown in FIG. 16, in the region E2 at the center of the chip, there are two contact portions 46de2 of the wiring-like portion 46b of the p electrode 48 and two contact portions 47d of the n electrode 47 closest thereto. On the other hand, the contact portion 46de1 of the p-electrode 46 existing in the region E1 at the four corners of the chip has only one contact portion 47d of the n-electrode 47 closest to the contact portion 46de1. Therefore, the resistance of the second path between one contact portion 46de2 of the p-electrode 46 and the contact portion 47d of the n-electrode 47 in the region E2 is small. In contrast, the resistance of the first path between one contact portion 46de1 of the p-electrode 46 and the contact portion 47d of the n-electrode 47 in the region E1 is large.

Therefore, in order to realize a uniform current distribution on the surface, the center O ′ of the width of the current blocking layer 18e1 in the region E1 is set to the center O of the width of the contact portion 46de1 of the wiring portion 46b. By keeping away from the closest contact part 47d in the center, the path toward the contact part 47d on the current blocking layer 18e1 is shortened, and the resistance of the first path is reduced. In the region E2, the center O ′ of the width of the current blocking layer 18e2 is brought closer to the wiring portion 47b at the center of the chip with respect to the center O of the width of the contact portion de2 of the wiring portion 46b. As a result, in the second path with low resistance, the resistance of the path toward the contact portion 47d on the current blocking layer 18e2 is increased. Conversely, the resistance of the path toward the long side of the chip on the current blocking layer 18e2 is reduced as in the second embodiment. As a result, the current density distribution on the surface of the chip, and hence on the surface of the current flowing vertically through the light emitting layer 12, can be made more uniform and uniform. As a result, the emission luminance can be made uniform and uniform on the surface.
In this embodiment, the special contact portions 16c and 17c shown in FIG. 1 of the first embodiment and FIG. 8 of the second embodiment may be provided.

  Example 8 is shown in FIG. Example 8 is a structure in which, in the structure of Example 3 shown in FIG. 11, the positional relationship between the current blocking layer and the contact portion of the p-electrode is alternately changed in the chip long side direction. Parts having the same functions as those in FIG. 11 are denoted by the same reference numerals. The wiring portions 36b extending in a straight line parallel to the chip long side of the p electrode 36 are arranged symmetrically with respect to the midpoint of the chip short side. The center O 'of the width of the current blocking layer 38e1 in the region E1 is moved away from the wiring portion 37b in the center of the chip with respect to the center O of the width of the wiring portion 36b. On the other hand, in the region E2, the center O 'of the width of the current blocking layer 38e2 is brought closer to the wiring portion 37b in the center of the chip with respect to the center O of the width of the wiring portion 36b. And the area | region E1 and the area | region E2 are alternately arrange | positioned in the chip | tip long side direction. Note that the four corners of the chip are defined as regions E1.

  With such a configuration, in the region E1, the path on the current blocking layer 38e1 in the direction from the wiring part 36b to the wiring part 37b at the center of the chip is shortened to reduce the resistance. On the other hand, in the region E2, the path on the current blocking layer 38e2 in the direction from the wiring portion 36b to the wiring portion 37b in the center of the chip is lengthened to increase the resistance of the path on the current blocking layer 38e2. On the contrary, the resistance on the current blocking layer 38e2 in the path toward the long side of the chip on the current blocking layer 38e2 is reduced as in the second embodiment. As described above, the region E1 in which the current density toward the wiring portion 37b of the n electrode 37 is increased and the region E2 in which the current density toward the long side of the chip is increased are mixed. The current density distribution on the surface of the current flowing vertically through the light emitting layer 12 can be made more uniform and uniform. As a result, the emission luminance can be made uniform and uniform on the surface. At the four corners of the chip, the current density between the wiring portion 36b and the wiring portion 37b at the center of the chip is smaller than that at the center, so this region is preferably the region E1.

As described above, the embodiments 1 to 8 have been described in many embodiments. However, the present invention aims to suppress an increase in driving voltage and make the light emission distribution on the chip surface uniform. Therefore, in addition to the above embodiments, the following embodiments can be obtained by combining the ideas of the above embodiments.
For each p-type current insertion portion, the emission distribution is more uniform than the emission distribution on the surface when the center O of the p-type current injection portion and the center O ′ of the current blocking layer coincide with each other. The position deviation and the direction between the center O ′ of the current blocking layer and the center O of the p-side current injection portion are determined. That is, when the center O ′ and the center O are matched, the p-type is such that the current density from the p-type current insertion portion toward the n-type current injection portion closest thereto is larger than the current density toward the long side of the chip. For the current injection portion, a structure in which the center O ′ of the second embodiment is brought closer to the n-type current insertion portion with respect to the center O is employed. Conversely, for the p-type current injection portion where the current density from the p-type current insertion portion toward the n-type current injection portion closest thereto is smaller than the current density toward the long side of the chip, the center O of Example 1 is used. A structure is adopted in which 'is away from the n-type current insertion portion with respect to the center O.
With the above configuration, the driving voltage can be reduced and the uniformity of the light emission distribution can be improved.

Further, in Example 4-8, the center O ′ of the width of the current blocking layer in the straight line L direction is larger in the straight line L direction than the center O of the width of the p side current injection portion in the straight line L direction. An arrangement far from the injection portion and the center O ′ of the width of the current blocking layer in the straight line L direction is n side in the straight line L direction from the center O of the width of the p-side current injection portion in the straight line L direction. This is an example in which arrangements close to the current injection portion are mixed.
In Examples 4 and 6, when there are a plurality of different values regarding the distance between the p-type current injection part and the n-type current injection part closest to the p-type current injection part, the maximum distance and the minimum distance When the average distance is ½ of the sum of the distances, for the p-type current injection portion (16 dy 1, 46 de 1) where the distance exists between the maximum distance and the average distance, the current blocking layer in the straight line L direction The width center O ′ is arranged so as to be farther from the n-side current injection portion in the straight line L direction than the width center O of the p-side current injection portion in the straight line L direction, and between the minimum distance and the average distance. For the p-type current injection portion ((16dy2, 46de2) where the distance exists, the center O ′ of the width of the current blocking layer in the straight line L direction is the width of the p-side current injection portion in the straight line L direction. Closer to the n-side current injection portion in the straight line L direction than the center O This is a special case of an example of a position arrangement, and in the case as shown in Fig. 15, when the p-type current injection portions are randomly arranged, the distance from the nearest n-type current injection portion is Since there are many, in such a case, the arrangement of the first embodiment and the arrangement of the second embodiment may be mixed by dividing the distance into two groups.

[Modification]
The light-emitting elements in Examples 1 to 8 are all face-up elements, but the present invention is not limited to face-up elements, and can be applied to flip-chip elements.

  The various modifications shown in the first embodiment can also be adopted in other embodiments.

  The light-emitting element of the present invention can be used for lighting devices, display devices, and the like.

10: Substrate 11: n layer 12: light emitting layer 13: p layer 14: transparent electrode 15: insulating film 16, 36: p electrode 16a, 17a, 36a, 37a: wire bonding part 16b, 16by1, 16by2, 17b, 36b, 36 by 1, 36 by 2, 37 b, 46 b: wiring portion 16 c, 16 d, 17 c, 17 d, 16 dy 1, 16 dy 2, 46 d, 46 de 1, 46 de 2, 47 d: contact portion 17, 37: n electrode 18, 18 e 1, 18 e 2, 18 y 1, 18 y 2, 28 , 38, 38y1, 38y2, 38e1, 38e2, 48e1, 48e2: current blocking layer 19: reflective film 21p, 21n: hole

Claims (19)

A semiconductor layer made of a group III nitride semiconductor and laminated in the order of an n layer, a light emitting layer, and a p layer, a transparent electrode made of a transparent conductive oxide located on the p layer, and in contact with the transparent electrode The one or more p-side current injection parts located in the n-layer, the one or more n-side current injection parts connected to the n layer, and the p-side current injection part between the p layer and the transparent electrode In a light emitting device made of a group III nitride semiconductor having a current blocking layer made of an insulator located below
The current blocking layer is provided in a region including the p-side current injection portion in plan view,
L is a straight line passing through an arbitrary position of the p-side current injection portion and the shortest distance from the position to the n-side current injection portion, and O is the center of the width of the p-side current injection portion in the straight line L direction. The center of the width of the current blocking layer in the straight line L direction is defined as O ′, and the center O and the center O ′ are not overlapped in the straight line L direction.
A light emitting element characterized by the above.   The center O ′ of the width of the current blocking layer in the straight line L direction is located farther from the n-side current injection part in the straight line L direction than the center O of the width of the p-side current injection part in the straight line L direction. The light-emitting element according to claim 1.   The width center O ′ of the current blocking layer in the straight line L direction is closer to the n-side current injection part in the straight line L direction than the width center O of the p-side current injection part in the straight line L direction. The light-emitting element according to claim 1.   The width center O ′ of the current blocking layer in the straight line L direction is located farther from the n-side current injection part in the straight line L direction than the width center O of the p-side current injection part in the straight line L direction. Arrangement and the center O ′ of the width of the current blocking layer in the straight line L direction is closer to the n-side current injection part in the straight line L direction than the center O of the width of the p-side current injection part in the straight line L direction The light emitting element according to claim 1, wherein arrangements of positions are mixed. In the case where there are a plurality of different values regarding the distance between the p-type current injection part and the n-type current injection part closest to the p-type current injection part, 1/2 of the sum of the maximum distance and the minimum distance Is the average distance,
For the p-type current injection portion where the distance exists between the maximum distance and the average distance, the center O ′ of the width of the current blocking layer in the straight line L direction is the p side in the straight line L direction. 5. The light emitting device according to claim 4, wherein the light emitting element is disposed at a position farther from the n-side current injection portion in the straight line L direction than the center O of the width of the current injection portion. In the case where there are a plurality of different values regarding the distance between the p-type current injection part and the n-type current injection part closest to the p-type current injection part, 1/2 of the sum of the maximum distance and the minimum distance Is the average distance,
For the p-type current injection portion where the distance exists between the minimum distance and the average distance, the center O ′ of the width of the current blocking layer in the straight line L direction is the p side in the straight line L direction. 6. The light emitting device according to claim 4, wherein the light emitting element is arranged in a position closer to the n-side current injection portion in a straight line L direction than a center O of a width of the current injection portion.   In each p-type current, the light emission distribution is more uniform than the light emission distribution on the surface when the center O of the p-type current injection portion and the center O ′ of the current blocking layer coincide with each other. 2. The light emitting device according to claim 1, wherein a position deviation and a direction of the center O ′ of the current blocking layer with respect to the center O of the p-side current injection portion are determined with respect to the entrance portion.   The whole or part of the blocking layer outline including the p-side current injection part of the planar pattern of the current blocking layer is a similar enlargement of the external line of the injection part of the planar pattern of the p-side current injection part. The light emitting device according to claim 1, wherein the light emitting device is a light emitting device.   The said blocking layer outline is a shape which notched a part of the shape which enlarged the injection | pouring outline of the injection | pouring part outline by making the gravity center of the said injection | pouring outline the center of gravity. Light emitting element.   10. The light emitting device according to claim 1, wherein the transparent electrode has a sheet resistance higher in a region on the current blocking layer than in a region on the p layer.   The light emitting device according to claim 1, wherein the transparent electrode is an indium oxide-based material.   The light emitting device according to claim 11, wherein the transparent electrode is IZO.   13. The light emitting device according to claim 1, wherein the current blocking layer is a transparent insulator containing oxygen as a constituent element.   The light emitting device according to claim 1, wherein the current blocking layer is a silicon compound. Said current blocking layer, the light emitting device according to claim 14, characterized in that the SiO _2. An insulating film located on the transparent electrode and having a hole for injecting a current into the transparent electrode; and a p-electrode located on the insulating film,
The p electrode is in contact with the transparent electrode through the hole, and a portion of the p electrode that is in contact with the transparent electrode inside the hole is the p-side current injection part.
The light emitting device according to claim 1, wherein the light emitting device is a light emitting device. An intermediate electrode positioned in contact with the transparent electrode, an insulating film positioned on the transparent electrode and the intermediate electrode, and having a hole for injecting a current into the intermediate electrode; and positioned on the insulating film A p-electrode,
The p-electrode is in contact with the intermediate electrode through the hole, and the intermediate electrode is the p-side current injection part.
The light emitting device according to claim 1, wherein the light emitting device is a light emitting device. A p-electrode positioned in contact with the transparent electrode;
The p-electrode has a connection part that is electrically connected to the outside of the element, and a wiring part that extends from the connection part in a wiring shape,
The p-electrode serves as the p-side current injection portion;
The light emitting device according to claim 1, wherein the light emitting device is a light emitting device.   19. The minimum value of the positional deviation between the center O ′ of the current blocking layer and the center O of the p-side current injection portion is 2 μm. 19. Light emitting element.

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