JP2023109274A - Light-emitting element - Google Patents

Abstract

To provide a light-emitting element with high light extraction efficiency.SOLUTION: A light-emitting element includes: a first semiconductor layer; an active layer; a second semiconductor layer; a first electrode electrically connected to the first semiconductor layer; a first insulating film disposed on a part of an upper surface of the second semiconductor layer; a second insulating film disposed on the upper surface of the second semiconductor layer; a light-transmitting conductive layer electrically connected to the second semiconductor layer and covering the first insulating film and the second insulating film; and a second electrode disposed on a part of an upper surface of the light-transmitting conductive layer and electrically connected to the second semiconductor layer. The first insulating film is disposed between the second semiconductor layer and the second electrode. An absolute value of a difference between a refractive index of the second semiconductor layer and a refractive index of the second insulating film is smaller than an absolute value of a difference between the refractive index of the second semiconductor layer and a refractive index of the light-transmitting conductive layer. An absolute value of a difference between the refractive index of the second semiconductor layer and a refractive index of the first insulating film is larger than the absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the light-transmitting conductive layer.SELECTED DRAWING: Figure 1

Description

Embodiments relate to light emitting devices.

As a light emitting element, a light emitting diode (LED) has been developed in which a p-type semiconductor layer, an active layer and an n-type semiconductor layer are laminated. In such a light emitting device, electrodes connected to the p-type semiconductor layer and the n-type semiconductor layer may be arranged on the light extraction surface of the light emitting device. Even in such a case, it is desired to improve the light extraction efficiency.

JP 2011-100839 A

The embodiments of the present invention have been made in view of the above problems, and an object thereof is to provide a light-emitting device with high light extraction efficiency.

A light emitting device according to an embodiment of the present invention includes a first semiconductor layer of a first conductivity type, and a first semiconductor layer disposed on a part of an upper surface of the first semiconductor layer and electrically connected to the first semiconductor layer. an electrode, an active layer arranged in a region where the first electrode is not arranged on the upper surface of the first semiconductor layer, a second conductive type second semiconductor layer arranged on the upper surface of the active layer, the a first insulating film arranged on a part of an upper surface of a second semiconductor layer; and a second insulating film arranged on a part of an upper surface of the second semiconductor layer where the first insulating film is not arranged. a film, a translucent conductive layer disposed on an upper surface of the second semiconductor layer, electrically connected to the second semiconductor layer, and covering the first insulating film and the second insulating film; a second electrode disposed on a portion of the upper surface of the conductive layer and electrically connected to the second semiconductor layer. In a cross-sectional view, the first insulating film is arranged between the second semiconductor layer and the second electrode. The absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the second insulating film is greater than the absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the translucent conductive layer. is also small. The absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the first insulating film is greater than the absolute value of the difference between the refractive index of the second semiconductor layer and the transparent conductive layer. is also big.

According to the embodiments of the present invention, a light emitting device with high light extraction efficiency can be realized.

1 is a top view showing a light emitting device according to a first embodiment; FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. 1; FIG. 2 is a cross-sectional view taken along line III-III shown in FIG. 1; FIG. 4A and 4B are schematic cross-sectional views showing the operation of the light emitting device according to the first embodiment; FIG. 4 is a top view showing a light emitting device according to a comparative example; FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5; 4A and 4B are schematic cross-sectional views showing the operation of a light-emitting element according to a comparative example; It is a top view which shows the light emitting element which concerns on the 1st modification of 1st Embodiment. It is a top view which shows the light emitting element which concerns on the 2nd modification of 1st Embodiment. FIG. 11 is a top view showing a light emitting device according to a third modified example of the first embodiment; It is a top view which shows the light emitting element which concerns on 2nd Embodiment. It is a top view which shows the light emitting element which concerns on the modification of 2nd Embodiment. It is a top view which shows the light emitting element which concerns on 3rd Embodiment. It is a top view which shows the light emitting element which concerns on 4th Embodiment. It is a top view which shows the light emitting element which concerns on 5th Embodiment.

<First Embodiment>
FIG. 1 is a top view showing a light emitting device according to this embodiment.
FIG. 2 is a cross-sectional view taken along line II--II shown in FIG.
FIG. 3 is a cross-sectional view taken along line III--III shown in FIG.
Note that each drawing is schematic, and is appropriately simplified and emphasized. For example, some components are drawn smaller and larger than they actually are. In addition, the numbers, positions and dimensional ratios of constituent elements are not necessarily consistent between the drawings. The same applies to other figures to be described later. Also, in FIG. 1, dots are attached to the first insulating film 40 and the second insulating film 50 to make the drawing easier to see. The same applies to other top views to be described later.

First, the configuration of the light emitting device 1 according to this embodiment will be schematically described.
The light emitting element 1 includes an n-type first semiconductor layer 11, a first electrode 20 disposed on a part of the upper surface of the first semiconductor layer 11 and electrically connected to the first semiconductor layer 11, and a first semiconductor layer 11. The active layer 12 arranged in the region where the first electrode 20 is not arranged on the upper surface of the layer 11, the p-type second semiconductor layer 13 arranged on the upper surface of the active layer 12, and the upper surface of the second semiconductor layer 13. a first insulating film 40 arranged on a part of the first insulating film 13a; , a translucent conductive layer 60 disposed on the upper surface 13a of the second semiconductor layer 13, electrically connected to the second semiconductor layer 13, and covering the first insulating film 40 and the second insulating film 50; and a second electrode 30 disposed on a portion of the upper surface of the layer 60 and electrically connected to the second semiconductor layer 13 . In a cross-sectional view, the first insulating film 40 is arranged between the second semiconductor layer 13 and the second electrode 30 . The absolute value of the difference between the refractive index of the second semiconductor layer 13 and the refractive index of the second insulating film 50 is more than the absolute value of the difference between the refractive index of the second semiconductor layer 13 and the transparent conductive layer 60. is also small. The absolute value of the difference between the refractive index of the second semiconductor layer 13 and the refractive index of the first insulating film 40 is greater than the absolute value of the difference between the refractive index of the second semiconductor layer 13 and the transparent conductive layer 60. is also big.

The configuration of the light emitting element 1 will be described in detail below.
As shown in FIGS. 1 to 3, the light emitting element 1 is arranged on the substrate 100. As shown in FIG. The type of substrate 100 is not particularly limited. The substrate 100 is, for example, a sapphire substrate for crystal growth of the semiconductor structure 10 . The shape of the light emitting element 1 is approximately a rectangular parallelepiped. The light emitting device 1 has a semiconductor structure 10 , a first electrode 20 , a second electrode 30 , a first insulating film 40 , a second insulating film 50 and a translucent conductive layer 60 .

Hereinafter, in this specification, the XYZ orthogonal coordinate system is adopted for convenience of explanation. The longitudinal direction of the light emitting element 1 is defined as the "first direction X", the lateral direction of the light emitting element 1 is defined as the "second direction Y", and the direction orthogonal to the first direction X and the second direction Y is defined as the "third direction Z". ”. Of the third direction Z, the direction (+Z) from the substrate 100 toward the light emitting element 1 is also called “up”, and the opposite direction (−Z) is also called “down”, but this expression is also for convenience. , independent of the direction of gravity. In this specification, "top view" refers to viewing from above, and "cross-sectional view" refers to viewing a cross section including the third direction Z.

The semiconductor structure 10 has a first semiconductor layer 11, an active layer 12, and a second semiconductor layer 13 in order from the substrate 100 side. The conductivity type of the first semiconductor layer 11 is the first conductivity type, for example, the n-type. The conductivity type of the second semiconductor layer 13 is the second conductivity type, for example, p-type. The first semiconductor layer 11 may be p-type and the second semiconductor layer 13 may be n-type.

An opening 14 is arranged in the active layer 12 and the second semiconductor layer 13 . The first semiconductor layer 11 is exposed at the bottom of the opening 14 . A first electrode 20 is arranged in a region of the upper surface of the first semiconductor layer 11 exposed at the bottom of the opening 14 . The first electrode 20 is arranged on part of the upper surface of the first semiconductor layer 11 . The active layer 12 is arranged in a region on the upper surface of the first semiconductor layer 11 where the first electrode 20 is not arranged. The second semiconductor layer 13 is arranged on the upper surface of the active layer 12 . Except for the opening 14, the first semiconductor layer 11, the active layer 12, and the second semiconductor layer 13 are rectangular in top view.

The first electrode 20 is made of a conductive material. The first electrode 20 has a first pad portion 21 and a first extending portion 22 extending from the first pad portion 21 . The first pad portion 21 is arranged on the +X side in the first direction X and in the center portion in the second direction Y, for example. When viewed from above, the shape of the first pad portion 21 is, for example, circular. In this embodiment, two first extending portions 22 are arranged. The two first extending portions 22 extend from the first pad portion 21 to both sides in the second direction Y, the extending direction continuously changes in an arc, and has a linear portion along the first direction X. ing.

A first portion 41 of the first insulating film 40 is arranged between the first semiconductor layer 11 and the first pad portion 21 in a cross-sectional view. When viewed from above, the shape of the first portion 41 is, for example, circular. When viewed from above, the diameter of the first portion 41 is larger than the diameter of the first pad portion 21 of the first electrode 20 . The first pad portion 21 is arranged on the first portion 41 . The first insulating film 40 is not arranged between the first semiconductor layer 11 and the first extending portion 22 , and the first extending portion 22 is in contact with the first semiconductor layer 11 . The first electrode 20 is electrically connected to the first semiconductor layer 11 by the contact of the first extending portion 22 with the first semiconductor layer 11 .

A second portion 42 , a third portion 43 and a fourth portion 44 of the first insulating film 40 , and a second insulating film 50 are arranged on a portion of the upper surface 13 a of the second semiconductor layer 13 . The material of the second insulating film 50 is different from the material of the first insulating film 40 . The film thickness of the first insulating film 40 is thicker than the film thickness of the second insulating film 50 . The second insulating film 50 is arranged in a part of the upper surface 13a of the second semiconductor layer 13 where the first insulating film 40 is not arranged. The planar arrangement of the first insulating film 40 and the second insulating film 50 will be described later.

A translucent conductive layer 60 is arranged on the upper surface 13 a of the second semiconductor layer 13 . The translucent conductive layer 60 is not arranged inside the opening 14 . The translucent conductive layer 60 can use a translucent and conductive material. The translucent conductive layer 60 covers the first insulating film 40 and the second insulating film 50 arranged on the second semiconductor layer 13 and covers the first insulating film 40 and the second insulating film 50 on the upper surface 13 a of the second semiconductor layer 13 . It touches the area where 50 is not arranged. Thereby, the translucent conductive layer 60 is electrically connected to the second semiconductor layer 13 . In cross-sectional view, the second portion 42 , the third portion 43 and the fourth portion 44 of the first insulating film 40 , and the second insulating film 50 are located between the second semiconductor layer 13 and the translucent conductive layer 60 . are placed. The first insulating film 40 and the second insulating film 50 are in contact with the second semiconductor layer 13 and the translucent conductive layer 60 .

A second electrode 30 is arranged on part of the upper surface of the translucent conductive layer 60 . The second electrode 30 is made of a conductive material. The second electrode 30 has a second pad portion 31 and second extending portions 32 and 33 extending from the second pad portion 31 . In this embodiment, for example, three second extending portions 32 and 33 are arranged. The second pad portion 31 is arranged on the −X side in the first direction X and in the center portion in the second direction Y, for example. When viewed from above, the shape of the second pad portion 31 is, for example, circular.

One second extending portion 32 extends linearly from the second pad portion 31 toward the +X side in the first direction X. As shown in FIG. The two second extending portions 33 extend from the second pad portion 31 to both sides in the second direction Y, and have linear portions along the first direction X, with the extending direction continuously changing in an arc. ing. Further, the second extending portion 33 extends along the first direction X, the extending direction continuously changes by drawing an arc, and has a straight portion along the second direction Y. As shown in FIG. A portion of the second extending portion 33 is located on the +X side in the first direction X with respect to the first pad portion 21 . The straight portion of the first extending portion 22 is arranged between the second extending portion 32 and the second extending portion 33 in the second direction Y. As shown in FIG.

When viewed from above, the second extending portion 32 of the second electrode 30 is positioned between the two first extending portions 22 of the first electrode 20 on the upper surface 13a of the second semiconductor layer 13 in the second direction Y. It is arranged in the first region R1. Further, when viewed from the top, the first pad portion 21 and the first extension portion 22 of the first electrode 20 are the two second electrodes 30 of the second electrode 30 on the upper surface 13a of the second semiconductor layer 13 in the second direction Y. It is arranged in the second region R2 located between the extension portions 33 . The first region R1 is part of the second region R2.

The second pad portion 31 and the second extending portions 32 and 33 are in contact with the translucent conductive layer 60 . Thereby, the second electrode 30 is electrically connected to the second semiconductor layer 13 through the translucent conductive layer 60 .

A detailed structure of the first insulating film 40 will be described.
The first insulating film 40 has a first portion 41 , a second portion 42 , a third portion 43 and a fourth portion 44 . The second portion 42 , the third portion 43 and the fourth portion 44 are arranged on the upper surface 13 a of the second semiconductor layer 13 . In a cross-sectional view, the second portion 42 is arranged between the second semiconductor layer 13 and the second pad portion 31 . When viewed from above, the shape of the second portion 42 is, for example, circular. The diameter of the second portion 42 is larger than the diameter of the second pad portion 31 . The second pad portion 31 is arranged on the second portion 42 .

In a cross-sectional view, the third portion 43 is arranged between the second semiconductor layer 13 and the second extending portion 32 . The third portion 43 has a straight portion along the first direction X when viewed from above. The second extension 32 is arranged on the third portion 43 . In the second direction Y, the width of the third portion 43 is greater than the width of the second extending portion 32 . Further, in a cross-sectional view, the fourth portion 44 is arranged between the second semiconductor layer 13 and the second extending portion 33 . The fourth portion 44 has a straight portion along the first direction X when viewed from above. In the second direction Y, the width of the fourth portion 44 is greater than the width of the second extending portion 33 . The second extension 33 is arranged on the fourth portion 44 .

Thus, the second portion 42 , the third portion 43 and the fourth portion 44 of the first insulating film 40 are arranged between the second semiconductor layer 13 and the second electrode 30 . When viewed from the top, the second electrode 30 is arranged within the region of the upper surface 13a of the second semiconductor layer 13 where the first insulating film 40 is arranged. Thereby, the light absorption by the second electrode 30 can be reduced, and the light extraction efficiency can be increased.

A detailed structure of the second insulating film 50 will be described.
The second insulating film 50 has, for example, a plurality of dot portions. The dot portions are separated from each other, for example. When viewed from above, the shape of each dot portion is, for example, circular or elliptical. However, it is not limited to this, and the shape of each dot portion may be, for example, a polygon, a triangle, or a square when viewed from above. Also, adjacent dot portions may be connected to each other. For example, the plurality of dot portions of the second insulating film 50 are arranged in a matrix along the first direction X and the second direction Y. As shown in FIG. However, it is not limited to this, and the plurality of dot portions of the second insulating film 50 may be arranged, for example, concentrically when viewed from above. Alternatively, the second insulating film 50 may be arranged in a grid pattern.

In this embodiment, the second insulating film 50 is arranged in a region of the upper surface 13a of the second semiconductor layer 13 where the first insulating film 40 and the opening 14 are not arranged.

An example of materials and dimensions of each member will be described.
The semiconductor structure 10 includes a nitride semiconductor such as gallium nitride (GaN), indium gallium nitride (InGaN), or the like. The first electrode 20 and the second electrode 30 are made of a conductive material, and are, for example, multilayer films having a plurality of metal layers. The first electrode 20 is, for example, nickel (Ni), rhodium (Rh), copper (Cu), gold (Au), titanium (Ti), chromium (Cr), tungsten (W), or an alloy containing these metals. can be used. In the second direction Y, the width of the first extending portion 22 of the first electrode 20 and the width of the second extending portions 32 and 33 of the second electrode 30 are, for example, 2 μm or more and 5 μm or less.

The first insulating film 40 is made of, for example, silicon oxynitride (SiON), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO), or niobium oxide (Nb ₂ O ₅ ). It is made of silicon oxynitride (SiON). The thickness of the first insulating film 40 is, for example, 50 nm or more and 500 nm or less. The thickness of the first insulating film 40 is, for example, 270 nm. In the second direction Y, the width of the third portion 43 and the width of the fourth portion 44 of the first insulating film 40 are, for example, 5 μm or more and 20 μm or less. The width of the third portion 43 of the first insulating film 40 and the width of the fourth portion 44 of the first insulating film 40 are each 11 μm, for example.

The second insulating film 50 is made of, for example, tantalum oxide (Ta ₂ O ₅ ), aluminum nitride (AlN), or silicon nitride (SiN), such as tantalum oxide (Ta ₂ O ₅ ). The thickness of the second insulating film 50 is, for example, 5 nm or more and 100 nm or less. The thickness of the second insulating film 50 is, for example, 10 nm. When the second insulating film 50 has a plurality of dot portions, the diameter of each dot portion of the second insulating film 50 is, for example, 2 μm or more and 10 μm or less. The thickness of the first insulating film 40 is preferably thicker than the thickness of the second insulating film 50 . As a result, the reflection efficiency at the interface between the first insulating film 40 and the second semiconductor layer 13 can be increased, and disconnection of the translucent conductive layer 60 by the second insulating film 50 can be reduced. The thickness of the first insulating film 40 is preferably 10 to 30 times the thickness of the second insulating film 50, for example. The thickness of the translucent conductive layer 60 from the upper surface of the second semiconductor layer 13 is, for example, 10 nm or more and 100 nm or less. The thickness of the translucent conductive layer 60 is, for example, 60 nm. The translucent conductive layer 60 is made of, for example, ITO (Indium-Tin-Oxide).

The absolute value of the difference between the refractive index _{n 13} of the second semiconductor layer 13 and the refractive index n ₅₀ of the second insulating film 50 (|n ₁₃ −n ₅₀ |) It is smaller than the absolute value of the difference from the refractive index n ₆₀ of the photoconductive layer 60 (|n ₁₃ −n ₆₀ |). The absolute value of the difference between the refractive index n ₁₃ of the second semiconductor layer 13 and the refractive index n ₄₀ of the first insulating film 40 (|n ₁₃ −n ₄₀ |) is the refractive index n 13 of the second semiconductor layer ₁₃ and the refractive index n ₆₀ of the translucent conductive layer 60 (|n ₁₃ −n ₆₀ |).

For example, the main component of the second semiconductor layer 13 is gallium nitride (GaN), and the refractive index _n13 is about 2.4. The first insulating film 40 is made of silicon oxynitride (SiON) and has a refractive index _n40 of about 1.6. The second insulating film 50 is made of tantalum oxide (Ta ₂ O ₅ ) and has a refractive index n ₅₀ of about 2.2. The translucent conductive layer 60 is made of ITO and has a refractive index _n60 of about 2.0.

Therefore, the absolute value of the difference between the refractive index n ₁₃ (approximately 2.4) of the second semiconductor layer 13 and the refractive index n ₅₀ (approximately 2.2) of the second insulating film 50 (|n ₁₃ −n ₅₀ |) is about 0.2. The absolute value of the difference (|n ₁₃ −n ₆₀ |) between the refractive index n ₁₃ (approximately 2.4) of the second semiconductor layer 13 and the refractive index n ₆₀ (approximately 2.0) of the translucent conductive layer 60 is about 0.4. The absolute value of the difference (|n ₁₃ −n ₄₀ |) between the refractive index n ₁₃ (approximately 2.4) of the second semiconductor layer 13 and the refractive index n ₄₀ (approximately 1.6) of the first insulating film 40 is approximately 0.8.

Therefore, the absolute value of the difference (approximately 0.2) between the refractive index of the second semiconductor layer 13 and the refractive index of the second insulating film 50 is It is smaller than the absolute value (about 0.4) of the difference from the refractive index. The absolute value of the difference (about 0.8) between the refractive index of the second semiconductor layer 13 and the refractive index of the first insulating film 40 is the refractive index of the second semiconductor layer 13 and the refractive index of the translucent conductive layer 60 is greater than the absolute value of the difference (approximately 0.4). That is, the following formula (1) is established.

|n ₁₃ −n ₅₀ |<|n ₁₃ −n ₆₀ |<|n ₁₃ −n ₄₀ | (1)

Next, the operation of the light emitting device according to this embodiment will be described.
FIG. 4 is a schematic cross-sectional view showing the operation of the light emitting device according to this embodiment.

As shown in FIG. 4, in the light emitting device 1, part of the light generated in the active layer 12 of the semiconductor structure 10 is transmitted through the translucent conductive layer 60 and emitted to the outside, as indicated by the optical path L1. do.

Further, as indicated by the optical path L2, another part of the light generated in the active layer 12 of the semiconductor structure 10 is refracted from the second semiconductor layer 13 into the second insulating film 50 and enters the second insulating film. The light is refracted from 50 into the translucent conductive layer 60 to be incident thereon, transmitted through the translucent conductive layer 60 and emitted to the outside. At this time, the absolute value of the difference between the refractive index of the second semiconductor layer 13 and the refractive index of the second insulating film 50 is the difference between the refractive index of the second semiconductor layer 13 and the transparent conductive layer 60. Since it is smaller than the absolute value, light is less reflected at the interface between the second semiconductor layer 13 and the second insulating film 50 than at the interface between the second semiconductor layer 13 and the translucent conductive layer 60 . If the second insulating film 50 were not arranged, the light incident on the translucent conductive layer 60 from the second semiconductor layer 13 would be likely to be reflected at the interface between the second semiconductor layer 13 and the translucent conductive layer 60 . As a result, the light extraction efficiency of the light emitting element 1 is lowered.

Further, as indicated by the optical path L2, the light emitted from the active layer 12 passes through the interface between the second semiconductor layer 13 and the second insulating film 50 and the interface between the second insulating film 50 and the translucent conductive layer 60. refracts at

Furthermore, as indicated by the optical path L3, still another portion of the light generated in the active layer 12 is reflected at the interface between the second semiconductor layer 13 and the first insulating film 40 and propagates through the semiconductor structure 10. After that, the light is emitted to the outside through the translucent conductive layer 60 . If the first insulating film 40 were not arranged, still another part of the light generated in the active layer 12 would pass through the second semiconductor layer 13 and the translucent conductive layer 60 and reach the second electrode 30. However, part of the light reaching the second electrode 30 is absorbed by the second electrode 30 . As a result, the light extraction efficiency of the light emitting element 1 is lowered.

In the light-emitting element 1, the current flowing from the second electrode 30 into the translucent conductive layer 60 flows along the XY plane due to the first insulating film 40 and the second insulating film 50, as indicated by the current path I1. expands. Thereby, the current distribution in the light emitting element 1 can be improved.

Effects of the present embodiment will be described.
In the light-emitting device 1 according to this embodiment, in a cross-sectional view, the second insulating film 50 is arranged between the second semiconductor layer 13 and the translucent conductive layer 60, and the refractive index of the second semiconductor layer 13 is and the refractive index of the second insulating film 50 is smaller than the absolute value of the difference between the refractive index of the second semiconductor layer 13 and the refractive index of the translucent conductive layer 60 . Therefore, when the light from the active layer 12 is emitted from the second semiconductor layer 13, the reflection at the interface between the second semiconductor layer 13 and the translucent conductive layer 60 can be reduced, and the light extraction efficiency can be improved. can.

Furthermore, in the light emitting device 1, the first insulating film 40 is arranged between the second semiconductor layer 13 and the second electrode 30 in a cross-sectional view. The absolute value of the difference between the refractive index of the second semiconductor layer 13 and the refractive index of the first insulating film 40 is greater than the absolute value of the difference between the refractive index of the second semiconductor layer 13 and the transparent conductive layer 60. Therefore, the light emitted from the second semiconductor layer 13 and reaching the first insulating film 40 is likely to be reflected at the interface between the second semiconductor layer 13 and the first insulating film 40 . This can reduce the amount of light emitted from the active layer 12 reaching the second electrode 30 , and can reduce the amount of light absorbed by the second electrode 30 . The light reflected by the first insulating film 40 may, for example, be repeatedly reflected between the substrate 100 and the first insulating film 40, propagate through the semiconductor structure 10, and eventually be emitted from the light emitting element 1. expensive. This also improves the light extraction efficiency.

Furthermore, in the light emitting element 1, the current path I1 between the second electrode 30 and the second semiconductor layer 13 spreads along the XY plane due to the first insulating film 40 and the second insulating film 50. The density distribution can be made uniform, and the emission intensity distribution of the light emitting element 1 can be made uniform.

<Comparative example>
FIG. 5 is a top view showing a light emitting device according to this comparative example.
FIG. 6 is a cross-sectional view taken along line VI-VI of FIG.
FIG. 7 is a schematic cross-sectional view showing the operation of the light emitting device according to this comparative example.

As shown in FIGS. 5 and 6, the light-emitting device 101 according to this comparative example has the first insulating film 40 and the second insulating film 50 arranged in comparison with the light-emitting device 1 according to the first embodiment. The difference is that there is no

As shown in FIG. 7, also in the light emitting element 101, part of the light generated in the active layer 12 of the semiconductor structure 10 is transmitted through the translucent conductive layer 60 and emitted to the outside, as indicated by the optical path L1. do. However, another part of the light generated in the active layer 12 of the semiconductor structure 10 is reflected at the interface between the second semiconductor layer 13 and the translucent conductive layer 60, as indicated by the optical path L4. Further, as indicated by the optical path L5, still another part of the light generated in the active layer 12 is incident on the second electrode 30 via the translucent conductive layer 60 and is absorbed by the second electrode 30. FIG. Therefore, the light extraction efficiency of the light emitting element 101 according to this comparative example is lower than the light extraction efficiency of the light emitting element 1 according to the first embodiment.

Also, as indicated by the current path I2, the current between the second electrode 30 and the second semiconductor layer 13 tends to concentrate in the region connecting the second electrode 30 and the second semiconductor layer 13 with the shortest distance. Therefore, when viewed from above, the current density distribution tends to be non-uniform, and the light emission intensity distribution of the light emitting element 101 becomes non-uniform.

<First Modification of First Embodiment>
FIG. 8 is a top view showing a light emitting device according to this modification.
In this modified example, different parts from the first embodiment will be mainly described, and descriptions of the same configurations, operations and effects as those of the first embodiment will be omitted. The same applies to other modifications and embodiments to be described later.

As shown in FIG. 8, in the light-emitting device 1a according to the present modification, when viewed from above, the surface density of the second insulating film 50 in the second region R2 is the same as that of the upper surface of the second semiconductor layer 13 excluding the second region R2. It is higher than the surface density of the second insulating film 50 in the region 13a. In one example, the areal density of the second insulating film 50 in the second region R2 is about twice the areal density of the second insulating film 50 in the region of the upper surface 13a of the second semiconductor layer 13 excluding the second region R2.

The surface density of the second insulating film 50 is the ratio of the second insulating film 50 per unit area. For example, when the second insulating film 50 has a plurality of dot portions, if the number of dot portions is constant, the surface density of the second insulating film 50 increases as the area of each dot portion increases. is constant, the surface density of the second insulating film 50 increases as the number of dot portions increases. Further, as described in the first embodiment, the second region R2 is located in the second direction Y between the two second extending portions 33 of the second electrode 30 on the upper surface 13a of the second semiconductor layer 13. is a region located in

In this modification, the areal density of the second insulating film 50 in the second region R2 is set higher than the areal density of the second insulating film 50 in the region other than the second region R2. As a result, while improving the light extraction efficiency in the second region R2, which tends to have a higher current density than in the region other than the second region R2, the second semiconductor layer 13 and the translucent conductive material in the region other than the second region R2 It is possible to secure a contact area with the layer 60 and reduce deterioration of the forward voltage.

<Second Modification of First Embodiment>
FIG. 9 is a top view showing a light emitting device according to this modification.
As shown in FIG. 9, in the light-emitting element 1b according to the present modification, when viewed from above, the surface density of the second insulating film 50 in the first region R1 is the same as that of the upper surface of the second semiconductor layer 13 excluding the first region R1. It is higher than the surface density of the second insulating film 50 in the region 13a. In one example, the areal density of the second insulating film 50 in the first region R1 is about twice the areal density of the second insulating film 50 in the region of the upper surface 13a of the second semiconductor layer 13 excluding the first region R1. . As described in the first embodiment, the first region R1 is positioned between the pair of first extending portions 22 of the first electrode 20 on the upper surface 13a of the second semiconductor layer 13 in the second direction Y. area.

In this modification, the areal density of the second insulating film 50 in the first region R1 is set higher than the areal density of the second insulating film 50 in the region other than the first region R1. As a result, while improving the light extraction efficiency in the first region R1, which tends to have a higher current density than in the regions other than the first region R1, the second semiconductor layer 13 and the translucent conductive material in the regions other than the first region R1 It is possible to secure a contact area with the layer 60 and reduce deterioration of the forward voltage.

<Third Modification of First Embodiment>
FIG. 10 is a top view showing a light emitting element according to this modification.
As shown in FIG. 10, in the light-emitting device 1c according to the present modification, when viewed from above, the surface density of the second insulating film 50 in the third region R3 is the same as that of the upper surface of the second semiconductor layer 13 excluding the third region R3. It is higher than the surface density of the second insulating film 50 in the region 13a. In one example, the areal density of the second insulating film 50 in the third region R3 is about twice the areal density of the second insulating film 50 in the region of the upper surface 13a of the second semiconductor layer 13 excluding the third region R3. . The third region R3 is a region located in the center in the first direction X in the first region R1, and is an elliptical region having the first direction X as the major axis, for example. The length of the third region R3 in the second direction Y is the same as the length of the first region R1, and the length of the third region R3 in the first direction X is shorter than the length of the first region R1. Therefore, of the outer edge of the third region R3, both ends in the second direction Y reach the outer edge of the first region R1, and the other portions are located inside the first region R1. In the example shown in FIG. 10, the tip of the second extending portion 32 of the second electrode 30 is located inside the third region R3. The shape of the third region R3 may be oval or rectangular. The third region R3 is part of the first region R1.

In this modification, the areal density of the second insulating film 50 in the third region R3 where the current density tends to be higher among the first regions R1 is set to is also high. As a result, while improving the light extraction efficiency in the third region R3, the contact area between the second semiconductor layer 13 and the translucent conductive layer 60 in regions other than the third region R3 is ensured, and the deterioration of the forward voltage is reduced. can do.

<Second embodiment>
FIG. 11 is a top view showing a light emitting device according to this embodiment.
As shown in FIG. 11, in the light-emitting device 2 according to the present embodiment, the second insulating film 50 does not cover the upper surface of the second semiconductor layer 13 when viewed from the top, as compared with the light-emitting device 1 according to the first embodiment. It is different in that it is arranged in a region of the second semiconductor layer 13 excluding the corner portion R4 of the second semiconductor layer 13a. That is, in the light emitting element 2, the second insulating film 50 is not arranged at the four corners R4. In this embodiment, the shape of each corner R4 is a right triangle when viewed from above.

A corner portion R4 where the first electrode 20 and the second electrode 30 are not arranged is a region having a lower current density than other regions. In the present embodiment, the second insulating film 50 is arranged in a region other than the corner R4, and the second insulating film 50 is not arranged in the corner R4. It is possible to secure a contact area between the second semiconductor layer 13 and the translucent conductive layer 60 and reduce the deterioration of the forward voltage.

<Modification of Second Embodiment>
FIG. 12 is a top view showing a light emitting element according to this modification.
As shown in FIG. 12, in the light-emitting element 2a according to this modified example, the second insulating film 50 is not arranged at the four corners R5 of the second semiconductor layer 13. As shown in FIG. The corner R5 where the first electrode 20 and the second electrode 30 are not arranged is a region having a lower current density than other regions, similarly to the corner R4 described above. In this modified example, each corner R5 has a rectangular shape when viewed from above. Further, the areal density of the second insulating film 50 in the second region R2 is higher than the areal density of the second insulating film 50 in the region of the upper surface 13a of the second semiconductor layer 13 excluding the corner portion R5 and the second region R2. . As a result, like the light emitting device 2 of the second embodiment, while improving the light extraction efficiency, the contact area between the second semiconductor layer 13 and the translucent conductive layer 60 at the corner portion R5 is ensured, and the forward voltage is reduced. aggravation can be reduced.

<Third Embodiment>
FIG. 13 is a top view showing a light emitting device according to this embodiment.
As shown in FIG. 13, in the light emitting element 3 according to the present embodiment, the second insulating film 50 is arranged only in the second region R2 when viewed from above, compared to the light emitting element 1 according to the first embodiment. The difference is that As a result, while improving the light extraction efficiency in the second region R2, the contact area between the second semiconductor layer 13 and the translucent conductive layer 60 is secured in regions other than the second region R2, thereby reducing deterioration of the forward voltage. can do.

In this embodiment, even if the areal density of the second insulating film 50 in the first region R1 is higher than the areal density of the second insulating film 50 in the region of the second region R2 excluding the first region R1, good. Further, the areal density of the second insulating film 50 in the third region R3 may be higher than the areal density of the second insulating film 50 in the region of the second region R2 excluding the third region R3.

<Fourth Embodiment>
FIG. 14 is a top view showing a light emitting device according to this embodiment.
As shown in FIG. 14, in the light-emitting element 4 according to the present embodiment, the second insulating film 50 is arranged only in the first region R1 in top view, compared to the light-emitting element 1 according to the first embodiment. The difference is that As a result, while improving the light extraction efficiency in the first region R1, the contact area between the second semiconductor layer 13 and the translucent conductive layer 60 is secured in regions other than the first region R1, thereby reducing the deterioration of the forward voltage. can do.

In this embodiment, even if the areal density of the second insulating film 50 in the third region R3 is higher than the areal density of the second insulating film 50 in the region of the first region R1 excluding the third region R3, good.

<Fifth Embodiment>
FIG. 15 is a top view showing a light emitting device according to this embodiment.
As shown in FIG. 15, in the light-emitting element 5 according to the present embodiment, the second insulating film 50 is arranged only in the third region R3 when viewed from above, compared to the light-emitting element 1 according to the first embodiment. The difference is that As a result, while improving the light extraction efficiency in the third region R3, the contact area between the second semiconductor layer 13 and the translucent conductive layer 60 is secured in regions other than the third region R3, thereby reducing the deterioration of the forward voltage. can do.

Each of the above-described embodiments and modifications thereof are examples embodying the present invention, and the present invention is not limited to these embodiments and modifications. For example, the present invention also includes additions, deletions, or modifications of some components in each of the above-described embodiments and modifications. Moreover, each of the embodiments and modifications described above can be implemented in combination with each other.

For example, the surface density of the second insulating film 50 may be set in three stages or more. For example, the surface density of the second insulating film 50 in the third region R3 is set to be the highest, the surface density of the second insulating film 50 in the first region R1 is set to be second highest, and the surface density of the second insulating film 50 in the second region R2 is set to be the highest. The second insulating film 50 has the lowest surface density in the area excluding the second region R2 and the corner R4 or R5 on the upper surface 13a of the second semiconductor layer 13, and the corner R4 or R5 has the lowest surface density. may have a form in which the second insulating film 50 is not arranged. In order to make the light emission intensity distribution of the light emitting element nearly uniform, the surface density of the second insulating film 50 is increased in the central portion of the light emitting element when viewed from above, and the surface area of the second insulating film 50 increases toward the periphery of the light emitting element. A low density is preferred.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, as a light source for lighting devices and display devices.

1, 1a, 1b, 1c, 2, 2a, 3, 4, 5: light emitting element 10: semiconductor structure 11: first semiconductor layer 12: active layer 13: second semiconductor layer 13a: upper surface of second semiconductor layer 14 : opening 20: first electrode 21: first pad 22: first extension 30: second electrode 31: second pad 32, 33: second extension 40: first insulating film 41: first portion 42: Second part 43: Third part 44: Fourth part 50: Second insulating film 60: Translucent conductive layer 100: Substrate 101: Light emitting element I1, I2: Current path L1, L2, L3, L4, L5 : optical path R1: first region R2: second region R3: third region R4: corner R5: corner X: first direction Y: second direction Z: third direction

Claims (9)

a first semiconductor layer of a first conductivity type;
a first electrode disposed on a portion of the upper surface of the first semiconductor layer and electrically connected to the first semiconductor layer;
an active layer arranged in a region where the first electrode is not arranged on the upper surface of the first semiconductor layer;
a second semiconductor layer of a second conductivity type disposed on the upper surface of the active layer;
a first insulating film disposed on a portion of the upper surface of the second semiconductor layer;
a second insulating film arranged on a part of the upper surface of the second semiconductor layer where the first insulating film is not arranged;
a translucent conductive layer disposed on the upper surface of the second semiconductor layer, electrically connected to the second semiconductor layer, and covering the first insulating film and the second insulating film;
a second electrode disposed on a portion of the upper surface of the translucent conductive layer and electrically connected to the second semiconductor layer;
with
In a cross-sectional view, the first insulating film is arranged between the second semiconductor layer and the second electrode,
The absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the second insulating film is greater than the absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the translucent conductive layer. is also small,
The absolute value of the difference between the refractive index of the second semiconductor layer and the refractive index of the first insulating film is greater than the absolute value of the difference between the refractive index of the second semiconductor layer and the transparent conductive layer. A large light-emitting element. 2. The light emitting device according to claim 1, wherein said first insulating film is further disposed between said first semiconductor layer and said first electrode in a cross-sectional view. The first electrode has a first pad portion and a first extending portion extending from the first pad portion,
3. The light emitting device according to claim 1, wherein said first insulating film is further arranged between said first semiconductor layer and said first pad portion in a cross-sectional view. the second electrode has a second pad portion and a second extending portion extending from the second pad portion;
In a cross-sectional view, the first insulating film is arranged between the second semiconductor layer and the second pad portion and between the second semiconductor layer and the second extending portion, and is arranged between the first semiconductor layer and the second pad portion. 4. The light-emitting device according to claim 3, wherein the light-emitting device is not arranged between the first extending portion. The first electrode has a first pad portion and a plurality of first extending portions extending from the first pad portion,
the second electrode has a second pad portion and a second extending portion extending from the second pad portion in a first direction from the second pad portion toward the first pad portion;
When viewed from above, the second extending portion is arranged in a first region located between the first extending portions on the top surface of the second semiconductor layer in a second direction orthogonal to the first direction,
3. The areal density of the second insulating film according to claim 1, wherein the surface density of the second insulating film in the first region is higher than the surface density of the second insulating film in a region on the upper surface of the second semiconductor layer excluding the first region. light-emitting element. The first electrode has a first pad portion and a first extending portion extending from the first pad portion,
the second electrode has a second pad portion and a plurality of second extending portions extending from the second pad portion;
the first extending portion and the second extending portion each have a portion extending along a first direction from the second pad portion toward the first pad portion;
When viewed from above, the first pad portion and the first extending portion are second pad portions positioned between the second extending portions on the upper surface of the second semiconductor layer in a second direction orthogonal to the first direction. placed in the area,
3. The areal density of the second insulating film in the second region is higher than the areal density of the second insulating film in a region of the upper surface of the second semiconductor layer excluding the second region. light-emitting element. The shape of the second semiconductor layer is rectangular in top view,
The light emitting device according to any one of claims 1 to 6, wherein the second insulating film is arranged in a region of the upper surface of the second semiconductor layer excluding corner portions of the second semiconductor layer when viewed from above. . The light emitting device according to any one of claims 1 to 7, wherein, when viewed from above, the second electrode is arranged in a region on the upper surface of the second semiconductor layer where the first insulating film is arranged. The light emitting device according to any one of claims 1 to 8, wherein the film thickness of the first insulating film is thicker than the film thickness of the second insulating film.

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