JP2016207870A - Light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element capable of improving the light extraction efficiency.SOLUTION: A light-emitting element according to an embodiment has: a semiconductor layer that has a regular hexagonal shape in a plan view; and a positive/negative pair of a first electrode and a second electrode provided on the semiconductor layer. The first electrode has a first pad part, and a first extension part extending from the first pad part and formed in a substantially rectangular shape. A first side that is one of four sides configuring the first extension part is opposed to any one corner of the semiconductor layer. The second electrode is arranged at an inner side from the first extension part.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a light emitting element.

  Conventionally, various developments have been made on light emitting elements in order to make the current density distribution uniform between electrodes provided on the upper surface of a semiconductor layer. For example, in a light-emitting element having a substantially rectangular semiconductor layer in plan view, one of the pair of positive and negative electrodes extends around the upper surface of the semiconductor layer in a substantially rectangular shape so as to surround the other electrode. An arranged light emitting element has been proposed (Patent Document 1).

JP 2001-345480 A

  On the other hand, when the light emitting element emits light, part of the light propagating inside the semiconductor layer is extracted to the outside from the side surface of the semiconductor layer, and there is light that is reflected by the side surface of the semiconductor layer and propagates to the upper surface side. . For this reason, there is a room for improvement in the light extraction efficiency because the light absorbed by the electrode tends to increase only by arranging the electrode along the periphery of the upper surface located in the vicinity of the side surface of the semiconductor layer.

  A light-emitting element according to an embodiment of the present invention includes a semiconductor layer having a regular hexagonal shape in a plan view, and a pair of positive and negative first and second electrodes provided on the semiconductor layer, and the first The electrode includes a first pad portion and a first extending portion extending from the first pad portion and formed in a substantially rectangular shape, and one of four sides constituting the first extending portion. The first side, which is one, is opposed to any one of the corners of the semiconductor layer, and the second electrode is a light emitting element disposed on the inner side of the first extending portion.

  According to the light emitting device according to the embodiment of the present invention, the light extraction efficiency can be improved.

3 is a plan view schematically showing the light emitting element according to Embodiment 1. FIG. 1B is a cross-sectional view taken along line A-A ′ of FIG. 1A schematically showing the light-emitting element according to Embodiment 1. FIG. 6 is a plan view schematically showing a light emitting element according to Embodiment 2. FIG. It is a top view which shows typically the light emitting element which concerns on a comparative example. FIG. 4 is a diagram showing a current density distribution of the light emitting element according to Example 1. 6 is a diagram showing a current density distribution of a light emitting device according to Example 2. FIG. It is a figure which shows the current density distribution of the light emitting element which concerns on a comparative example.

  Hereinafter, embodiments for implementing a light-emitting device according to the present invention will be described with reference to the drawings. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members in principle, and the detailed description will be omitted as appropriate.

<Embodiment 1>
FIG. 1A is a plan view schematically showing the light emitting element 100 according to Embodiment 1. FIG. FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. 1A schematically showing the light emitting device 100 according to the first embodiment.

  As illustrated in FIG. 1A, the light-emitting element 100 according to Embodiment 1 includes a semiconductor layer 20 (20a to 20c) having a regular hexagonal shape in plan view, and a pair of positive and negative first electrodes 40 provided on the semiconductor layer 20. , 41, 44 and second electrodes 50, 42, 43. The first electrodes 40, 41, and 44 include a first pad portion 40 and a first extending portion 41 that extends from the first pad portion 40 and is formed in a substantially rectangular shape. The first side 41a, which is one of the four sides constituting the, faces one of the corners of the semiconductor layer 20. The second electrodes 50, 42, and 43 are disposed on the inner side than the first extending portion 41. Note that “upper” in this specification refers to the side on which the first electrodes 40, 41, 44 and the second electrodes 50, 42, 43 are provided with respect to the semiconductor layer 20, and is the upward direction in FIG. 1B. .

  The first side 41 a of the first extending portion faces the corner of the semiconductor layer 20, so that the semiconductor layer is provided along two sides 21 a and 21 b constituting the corner, ie, along the periphery of the so-called semiconductor layer 20. Since the ratio of the area of the electrode to the upper surface of 20 can be reduced, light from the semiconductor layer 20 (20b) absorbed by the electrode can be reduced. Furthermore, since a closed region surrounded by the first side 41a of the first extending portion and the two sides 21a and 21b constituting the corner portion of the semiconductor layer 20 is formed, the first of the first extending portion is formed. The current from the side 41a can easily spread to the periphery of the semiconductor layer 20, and the area with low current density can be reduced. As a result, the light emitting element 100 according to the first embodiment can improve the light extraction efficiency and reduce the bias of the current density distribution on the upper surface of the semiconductor layer 20.

  Further, the first side 41a of the first extending portion is not parallel to any of the two sides 21a and 21b constituting the corners of the semiconductor layer 20, that is, the side surfaces of the so-called neighboring semiconductor layer 20, and therefore the side surface of the semiconductor layer 20 It is possible to reduce the light reflected toward the first side 41a of the first extending portion. On the other hand, the light extracted from the region surrounded by the first side 41a of the first extending portion and the two sides 21a and 21b constituting the corners of the semiconductor layer 20 is increased. Efficiency can be further improved.

More specifically, as illustrated in FIG. 1B, the light-emitting element 100 according to Embodiment 1 includes a substrate 10, a semiconductor layer 20, a second conductivity type semiconductor layer 20 a, and an active layer 20 b in order from the substrate 10 side. And a first conductivity type semiconductor layer 20c. Part of the second conductive type semiconductor layer 20a is exposed from the active layer 20b and the first conductive type semiconductor layer 20c, and the second electrodes 50 and 42 are formed on the exposed upper surface of the second conductive type semiconductor layer 20a. , 43 are provided. On the other hand, the first electrodes 40, 41, and 44 are provided on the upper surface of the translucent electrode 30 such as ITO provided on almost the entire surface of the first conductive semiconductor layer 20c, and are electrically connected to the first conductive semiconductor layer 20c. Connected. Further, the upper surface side of the semiconductor layer 20 is covered with a protective film 60 such as SiO ₂ , and a part of the upper surface of each pad portion 40, 50 of the first electrode and the second electrode is exposed from the protective film 60. Yes.

  As shown in FIG. 1A, the first electrode includes a substantially circular first pad portion 40 electrically connected to an external connection member (not shown) such as a wire, and the first pad portion 40 to the first pad portion. And a first extending portion 41 formed to be substantially rectangular by extending narrower than the diameter of 40. The first extending portion 41 includes a first side 41a facing one of the corners of the semiconductor layer 20, a second side 41b adjacent to the first side 41a, a second side 41b, and the first side 41a. And a fourth side 41d adjacent to the third side 41c and facing the second side 41b, and further connecting four adjacent corners 41e to 41c. Each of 41h has a curved shape so that current does not concentrate excessively. The second side 41b of the first extending portion is a side adjacent to the sides 21a and 21b constituting the corners of the semiconductor layer 20 opposed to the first side 41a among the six sides 21a to 21f constituting the semiconductor layer 20. (Hereinafter referred to as the first semiconductor side 21c). The first pad portion 40 is disposed on the second side 41b of the first extending portion, and is disposed in a relatively wide region between the second side 41b and the first semiconductor side 21c. For this reason, it is possible to reduce the bias as compared with light extracted outside from a narrow region surrounded by the first side 41a of the first extending portion and the two sides 21a and 21b constituting the corners of the semiconductor layer 20. Can do. In the first embodiment, the first side to the fourth side 41a to 41d constituting the first extending portion 41 are all parts extending linearly.

  In addition, the first side 41a of the first extending portion is located on the end of the first semiconductor side 21c near the first side 41a and the first side 41a of the second semiconductor side 21f facing the first semiconductor side 21c. It arrange | positions outside the 1st straight line L1 which ties the edge part of a near side. On the other hand, the third side 41c facing the first side 41a of the first extending portion is similarly the end of the first semiconductor side 21c near the third side 41c and the third side 41c of the second semiconductor side 21f. Is disposed on the outer side of the second straight line L <b> 2 that connects the end portion on the side close to the surface of the semiconductor layer 20 and faces one of the corner portions of the semiconductor layer 20. Thereby, the area | region where a current density falls can be reduced more in the area | region between the corner | angular part of the semiconductor layer 20 which the 1st edge | side 41a and the 3rd edge | side 41c of a 1st extending | stretching part respectively oppose.

  The second electrode includes a second pad portion 50 and two second extending portions 42 extending from the second pad portion 50 along the first extending portion 41. The second pad portion 50 is provided at a position closer to the fourth side 41d than the second side 41b of the first extending portion. At this time, the fourth side 41d of the first extending portion may have a separation region h separated by about 50 μm or more and 400 μm or less, and further by about 100 μm or more and 300 μm as in the first embodiment, but is not limited thereto. . In addition, it is preferable that the 2nd pad part 50 is arrange | positioned so that the separation area | region h may be opposed. Accordingly, it is possible to reduce the bias of the current between the second pad portion 50 that tends to increase the current density around the disposed portion and the fourth side 41d of the first extending portion, and the first Light from the semiconductor layer 20 (20b) absorbed by the fourth side 41d of the extending portion can be reduced. Of the two second extending portions 42, one second extending portion 42 extends from the second pad portion 50 along the fourth side 41d on the first side 41a side of the first extending portion, and further, the first straight line L1. The outer side is extended along the first side 41a of the first extending portion. The other second extending portion 42 extends from the second pad portion 50 along the fourth side 41d on the third side 41c side of the first extending portion, and further outside the second straight line L2 of the first extending portion. It extends along the third side 41c. As a result, a part of the current supplied to the region between the first pad portion 40 and the second pad portion 50, which tends to have a high current density, is converted into the first side 41 a and the third side of the first extending portion. Since it can be supplied in the vicinity of 41c, the bias of the current density distribution on the upper surface of the semiconductor layer 20 can be further reduced.

Further, the tips of the two second extending portions 42 are opposed to the corner portions 41e and 41f of the first extending portion in the extending direction, respectively. The shortest distance a ₁ between the tip of the second extending portion 42 extending along the first side 41a of the first extending portion and the corner portion 41e connecting the first side 41a and the second side 41b of the first extending portion is It is preferable that the length is longer than the shortest distance b ₁ between the first side 41a of the first extending portion and the portion of the second extending portion 42 extending along the first side 41a. Thereby, the first side 41a of the first extension part away from the first pad part 40 where the current tends to be deficient than between the tip of the second extension part 42 and the second side 41b of the first extension part. The current supplied between the second extending portion 42 extending along the first side 41a can be increased. Similarly, the current supplied between the third side 41c of the first extension part and the portion of the second extension part 42 extending along the third side 41c is increased, and the current to the first side 41a side is increased. In order to reduce the unevenness of the density distribution, the tip of the second extending portion 42 extending along the third side 41c of the first extending portion is connected to the third side 41c and the second side 41b of the first extending portion. the shortest distance a ₂ between the corner portion 41f includes a third side 41c of the first extending portion, the long is preferred than the shortest distance b ₂ between the site of the second extending portion 42 extending along the third side 41c . More specifically, the shortest distances a ₁ and a ₂ are each preferably about 90 μm to 190 μm, and more preferably about 100 μm to 150 μm. Further, the shortest distances b ₁ and b ₂ are each preferably about 40 μm to 150 μm, and more preferably about 60 μm to 100 μm.

Further, a fourth side 41d which is adjacent to the first side 41a of the first extending portion, the shortest distance c ₁ between portions of the second extending portion 42 extending along the fourth side 41d are the first extending portion It is preferable that the distance is longer than the shortest distance b ₁ between the first side 41a and the portion of the second extending portion 42 extending along the first side 41a. As a result, current is less biased between the fourth side 41d closer to the second pad portion 50 than the first side 41a of the first extended portion and the second extended portion 42 along the fourth side 41d. In addition, current can be collected in the vicinity of the first side 41a. Similarly, the current is less biased between the fourth side 41d adjacent to the third side 41c of the first extension part and the second extension part 42 along the fourth side 41d, and the third side In order to collect current in the vicinity of the side 41c, the shortest distance c between the fourth side 41d adjacent to the third side 41c of the first extension part and the portion of the second extension part 42 extending along the fourth side 41d. _2, a third side 41c of the first extending portion, the long is preferred than the shortest distance b ₂ between the site of the second extending portion 42 extending along the third side 41c. More specifically, the shortest distances c ₁ and c ₂ are each preferably about 90 μm or more and 190 μm or less, and more preferably about 100 μm or more and 150 μm or less. Further, the shortest distances b ₁ and b ₂ are each preferably about 40 μm to 150 μm, and more preferably about 60 μm to 100 μm.

  Further, the second electrode includes a third extending portion 43 that extends linearly from the second pad portion 50 toward the first pad portion 40 between the two second extending portions 42. On the other hand, the first electrode extends between the third extending portion 43 and the two second extending portions 42 in two fourth extending directions extending in parallel from the first pad portion 40 to the third extending portion 43. Part 44. As a result, the current can be spread in the direction in which the first pad portion 40 and the second pad portion 50 face each other, so that the current density distribution in the region between the first pad portion 40 and the second pad portion 50 is uneven. Can be reduced.

On the diagonal L3 of the semiconductor layer 20 parallel to the second side 41b of the first extending portion, the distance b ₁ (or b ₂ ) between the adjacent first extending portion 41 and the second extending portion 42 is the adjacent second It is preferably shorter than the distance d ₁ (or d ₂ ) between the extending portion 42 and the fourth extending portion 44. That is, each of the distances b ₁ and b ₂ between the first side 41 a and the third side 41 c of the first extension part and the two second extension parts 42 adjacent to the first side 41 a and the third side 41 c is the same as the two second extension parts 42. The distances d ₁ and d ₂ between the two fourth extending portions 44 adjacent to each other are preferably shorter (distance b ₁ <distance d ₁ and distance b ₂ <distance d ₂ ). Such an extending portion tends to make it difficult for a current to flow as the distance from the first pad portion 40 and the second pad portion 50 increases. For this reason, by narrowing the distance between the first extending portion 41 and the second extending portion 42 adjacent thereto, current can be easily diffused even on the peripheral side of the semiconductor layer 20. The distance b ₁ and the distance b ₂ can be different, but are preferably the same. For example, any distance is preferably about 40 μm to 150 μm, and more preferably about 60 μm to 100 μm. Similarly, the distance d ₁ and the distance d ₂ are preferably about 90 μm to 190 μm, and more preferably about 100 μm to 130 μm.

Further, on the diagonal line L3 of the semiconductor layer 20 parallel to the second side 41b of the first extending portion, the distance e ₁ (or e ₂ ) between the third extending portion 43 and the fourth extending portion 44 is adjacent to the second side. It is preferable that the distance d ₁ (or d ₂ ) between the extending portion 42 and the fourth extending portion 44 is longer. That is, each of the distances d ₁ and d ₂ between the two second extending portions 42 and the two fourth extending portions 44 adjacent to each of the two second extending portions 42 is the third extending portion 43 and the two fourth extending portions adjacent thereto. It is preferable that the distances e ₁ and e ₂ with the portion 44 are shorter (distance d ₁ <distance e ₁ and distance d ₂ <distance e ₂ ). The third extending portion 43 on the straight line connecting the first pad portion 40 and the second pad portion 50 and the two fourth extending portions 44 adjacent thereto tend to easily flow current. For this reason, it can suppress that an electric current density becomes high too much by widening the space | interval of the 3rd extending | stretching part 43 and the 4th extending | stretching part 44. FIG. The distance d ₁ and the distance d ₂ can be different but are preferably the same. For example, each distance is preferably about 90 μm to 190 μm, and more preferably about 100 μm to 130 μm. Similarly, the distance e ₁ and the distance e ₂ are preferably about 100 μm to 200 μm, and more preferably about 130 μm to 150 μm.

In the first embodiment, the distances (e ₁ , e ₂ ) between the third extending part 43 and the fourth extending part 44 and the distances (d ₁ ) between the second extending part 42 and the fourth extending part 44 in the order of increasing distance. , D ₂ ), and the distance (b ₁ , b ₂ ) between the first extending portion 41 and the second extending portion 42, the bias of the current density distribution on the upper surface of the semiconductor layer 20 can be further reduced.

Further, the shortest distance f ₁ (or f ₂ ) between the tip of the fourth extending portion 44 and the portion of the second extending portion 42 extending along the fourth side 41d of the first extending portion is the first extending portion. It is preferably longer than the shortest distance c ₁ (or c ₂ ) between the fourth side 41d and the portion of the second extending portion 42 extending along the fourth side 41d. Thereby, it is possible to suppress the current density from becoming excessively high in the region between the first pad portion 40 and the second pad portion 50, and to diffuse the current toward the fourth side 41d of the first extending portion. Moreover, it is preferable that the shortest distance f ₁ (or f ₂ ) is shorter than the shortest distance g between the first pad portion 40 and the tip of the third extending portion 43, and the _first distance is shorter than the shortest distance f ₁ (or f ₂ ). It is preferable that the shortest distance a ₁ (or a ₂ ) between the tip end of the two extending portions 42 and the corner portion 41e (or 41f) of the first extending portion opposite thereto is short. In this manner, the current is spread toward the first side 41a side and the third side 41c side of the first extending portion by narrowing the interval as the distance from the straight line connecting the first pad portion 40 and the second pad portion 50 increases. Can do. More specifically, the shortest distances f ₁ and f ₂ may be different but are preferably the same. For example, each distance is preferably about 120 μm to 190 μm, and more preferably about 120 μm to 150 μm. It is. The shortest distance g is preferably about 120 μm to 200 μm, and more preferably about 130 μm to 170 μm.

  Hereinafter, each structure which concerns on Embodiment 1 is explained in full detail.

(Semiconductor layer)
The semiconductor layer 20 is a light emitting unit in the light emitting device 100. For example, the first conductive type semiconductor layer 20c and the second conductive type semiconductor layer 20a, and the first conductive type semiconductor layer 20c and the second conductive type semiconductor layer 20a. The thing comprised by the active layer 20b arrange | positioned between is mentioned. The first conductivity type semiconductor layer 20c and the second conductivity type semiconductor layer 20a have different conductivity types. The first conductive semiconductor layer 20c and the second conductive semiconductor layer 20a may have a single layer structure or a stacked structure. In the case of a stacked structure, not all the layers constituting the first conductivity type semiconductor layer 20c or the second conductivity type semiconductor layer 20a need to exhibit the first conductivity type or the second conductivity type. The active layer 20b may be either a single quantum well structure or a multiple quantum well structure formed in a thin film in which a quantum effect is generated. Material used for the semiconductor layer 20 is not particularly limited, for _{example, In X Al Y Ga 1-} XY N (0 ≦ X, 0 ≦ Y, X + Y ≦ 1) , and the like.

  The semiconductor layer 20 includes, for example, one of the second conductivity type semiconductor layers 20a in order to arrange first electrodes 40, 41, 44 and second electrodes 50, 42, 43, which will be described later, on the same surface side of these semiconductor layers 20. The first conductivity type semiconductor layer 20c is laminated on the second conductivity type semiconductor layer 20a so that the portion is exposed, or the second conductivity type is exposed so that a part of the first conductivity type semiconductor layer 20c is exposed. The semiconductor layer 20a is stacked on the first conductivity type semiconductor layer 20c.

  The planar shape of the semiconductor layer 20 can be substantially a regular hexagonal shape. The corner may be rounded and allows an angle of up to about 120 ° ± 5 °. Also, the length of one side is allowed up to about ± 5% of the length of the other side. Further, the diagonal distance on the upper surface of the semiconductor layer 20 is, for example, about several hundred μm to several thousand μm, and preferably about 600 μm to 1500 μm.

The semiconductor layer 20 is usually stacked on the substrate 10. The material of the substrate 10 is not particularly limited, and examples thereof include sapphire (Al ₂ O ₃ ). However, in the light emitting element 100 according to Embodiment 1, such a substrate 10 does not necessarily exist.

(First electrode and second electrode)
The first electrodes 40, 41, 44 and the second electrodes 50, 42, 43 are members for supplying current to the semiconductor layer 20 from the outside, and are formed as a pair of positive and negative electrodes on the same surface side of the semiconductor layer 20. The semiconductor layers 20 are opposed to each other. In the first embodiment, the first electrodes 40, 41, 44 are p-side electrodes and the second electrodes 50, 42, 43 are n-side electrodes. However, the present invention is not limited to this, and the first electrodes 40, 41, 44 are not limited thereto. Can be an n-side electrode, and the second electrodes 50, 42, and 43 can be p-side electrodes. Moreover, as materials used for the first electrodes 40, 41, 44 and the second electrodes 50, 42, 43, for example, metals such as Ni, Rh, Ru, Cr, Au, W, Pt, Ti, and Al, Alternatively, alloys of these metals can be given, and among them, it is preferable to use a multilayer structure in which Ti / Pt / Au, CrRh / Pt / Au, and the like are laminated in order.

  The first electrodes 40, 41, 44 and the second electrodes 50, 42, 43 include pad portions 40, 50 and extending portions 41, 44, 42, 43 extending from the pad portions 40, 50, respectively. Yes. The pad portions 40 and 50 are portions that are electrically connected to an external circuit (not shown), and are, for example, portions to which wires are bonded. The pad portions 40 and 50 are preferably disposed on the inner side of the side surface of the semiconductor layer 20 in a top view, and the pad portion (first pad portion) 40 of the first electrode and the pad portion (first electrode) of the second electrode. The forward voltage can be reduced by reducing the distance from the (2 pad portion) 50. Although the planar shape of the 1st pad part 40 and the 2nd pad part 50 is not specifically limited, For example, it can be set as shapes, such as circular and a regular polygon. Among these, considering the bondability with a wire by wire bonding, a circular shape having a diameter of about 70 μm to 150 μm or a shape similar to this is preferable. Further, the arrangement of the first pad portion 40 and the second pad portion 50 in the first embodiment is opposed to the direction of the opposite sides of the semiconductor layer 20 in plan view. For example, as in the second embodiment, the semiconductor layer It can also be opposed to 20 diagonal directions.

  The extending portions 41, 44, 42, and 43 are portions for uniformly diffusing the current supplied to the first pad portion 40 and the second pad portion 50 to the semiconductor layer 20. The width | variety of each extending | stretching part 41,44,42,43 is not specifically limited, For example, it shall be about 5-30% of width | variety with respect to the diameter of the 1st pad part 40 or the 2nd pad part 50. More preferably, the width is about 5 to 15%, and more specifically, the width is preferably about 2 μm to 15 μm.

  <Embodiment 2>

  FIG. 2 is a plan view schematically showing the light emitting device 200 according to the second embodiment.

  As shown in FIG. 2, the light emitting device 200 according to the second embodiment includes the first electrodes 40, 41, 44 and the second electrodes 50, 42, 43 at 90 ° centering on the central portion of the semiconductor layer 20 in the light emitting device 100. Except for rotation, it has substantially the same structure as that of the first embodiment. In addition, about the same structure, description is abbreviate | omitted suitably.

  The light-emitting element 200 according to Embodiment 2 includes a semiconductor layer 20 (20a, 20b, 20c) having a regular hexagonal shape in plan view, and a pair of positive and negative first electrodes 40, 41, 44 provided on the semiconductor layer 20. And at least second electrodes 50, 42, and 43. The first electrode includes a first pad portion 40 and a first extending portion 41 extending from the first pad portion 40 and formed in a substantially rectangular shape. The first side 41 a, which is one of the four sides constituting the first extending portion 41, faces one of the corners of the semiconductor layer 20, and further includes a first pad portion 40. Further, the second electrode is disposed on the inner side of the first extending portion 41a. Accordingly, since the ratio of the area of the electrode in the upper surface of the semiconductor layer can be reduced as compared with the two sides 21a and 21b constituting the corner portion, that is, provided along the periphery of the so-called semiconductor layer 20, it is absorbed by the electrode. The light from the semiconductor layer 20 (20b) can be reduced. Furthermore, since a closed region surrounded by the first side 41a of the first extending portion and the two sides 21a and 21b constituting the corner portion of the semiconductor layer 20 is formed, the first of the first extending portion is formed. The current from the side 41a can easily spread to the periphery of the semiconductor layer 20, and the area with low current density can be reduced. Furthermore, since the first side 41a of the first extending portion is not parallel to any of the two sides 21a and 21b constituting the corner of the semiconductor layer, that is, the side surface of the so-called neighboring semiconductor layer 20, the side surface of the semiconductor layer 20 It is possible to reduce the light reflected toward the first side 41a of the first extending portion. On the other hand, the light extracted outside from the region surrounded by the first side 41a of the first extending portion and the two sides 21a and 21b constituting the corners of the semiconductor layer 20 can be increased.

  Further, the second side 41b adjacent to the first side 41a of the first extending portion is a side adjacent to the sides 21a and 21b forming the corners among the six sides 21a to 21f forming the semiconductor layer 20. 1 facing the semiconductor side 21c. The first side 41a of the first extending portion is an end of the first semiconductor side 21c that is closer to the first side 41a and a first side of the second semiconductor side 21f that faces the first semiconductor side 21c. It arrange | positions outside the 1st straight line L1 which ties the edge part near 41a. The third side 41c facing the first side 41a of the first extending portion is an end of the first semiconductor side 21c that is closer to the third side 41c and a third side 41c of the second semiconductor side 21f. It is arrange | positioned on the outer side rather than the 2nd straight line L2 which connects the edge part near the side. The first pad portion 40 is disposed on the second side 41b of the first extending portion, and is disposed in a relatively wide region between the second side 41b and the first semiconductor side 21c. Thereby, the area | region where a current density falls can be reduced more in the area | region between the corner | angular part of the semiconductor layer 20 which the 1st edge | side 41a and the 3rd edge | side 41c of a 1st extending | stretching part respectively oppose.

  The light emitting element 200 according to the second embodiment having the above configuration improves the light extraction efficiency as in the first embodiment by the first side 41a of the first extending portion facing the corner of the semiconductor layer 20. In addition, the bias of the current density distribution on the upper surface of the semiconductor layer 20 can be reduced.

  Hereinafter, light emitting devices according to examples of the present invention will be described.

<Example 1>
The light-emitting element according to Example 1 has substantially the same structure as the light-emitting element 100 according to Embodiment 1, and will be described with reference to FIGS. 1A and 1B. In addition, about the same structure, description is abbreviate | omitted suitably.

  As shown in FIGS. 1A and 1B, the light emitting device according to Example 1 includes a substrate 10, an n-type semiconductor layer (second conductivity type semiconductor layer) 20 a provided on the substrate 10, an active layer 20 b, and a p-type. A semiconductor layer 20 having a semiconductor layer (first conductivity type semiconductor layer) 20c in order, and an n-side electrode (second electrode) 50 provided on the n-type semiconductor layer 20a exposed from the active layer 20b and the p-type semiconductor layer 20c. , 42, 43 and p-side electrodes (first electrodes) 40, 41, 44 disposed on the p-type semiconductor layer 20c so as to surround the n-side electrode in plan view.

  The planar shape of the semiconductor layer 20 is a regular hexagon having a side length of about 500 μm.

  Each of the first electrode and the second electrode has pad portions 40, 50 and narrow extending portions 41, 42, 43, 44 extending from the pad portions 40, 50. The pad portion (first pad portion) 40 of the first electrode and the pad portion (second pad portion) 50 of the second electrode each have a substantially circular shape with a diameter of about 80 μm. The distance between the centers of the first pad portion 40 and the second pad portion 50 is about 470 μm.

Further, corner portions 41e and 41f connecting the second side 41b of the first extending portion 41 extending from the first pad portion 40 and the first side 41a or the third side 41c adjacent thereto, and the second pad portion 50. The shortest distances a ₁ and a _{2 to} the tips of the two second extending portions 42 extending from are about 100 μm. The shortest distances b ₁ and b ₂ between the first side 41a or the third side 41c of the first extending part and the portion of the second extending part 42 along the first side 41a or the third side 41c are about 60 μm. The shortest distances c ₁ and c ₂ between the fourth side 41d of the first extending portion and the portion of the second extending portion 42 along this are each about 90 μm. The distances d ₁ and d ₂ between the second extending portion 42 and the fourth extending portion 44 adjacent on the diagonal line L3 of the semiconductor layer 20 are about 100 μm. The distances e ₁ and e ₂ between the third extending portion 43 and the two fourth extending portions 44 on the diagonal line L3 of the semiconductor layer 20 are each about 130 μm. The shortest distances f ₁ and f ₂ between the tip of the fourth extending portion 44 and the portion of the second extending portion 42 extending along the fourth side 41d of the first extending portion are about 165 μm. The shortest distance g between the first pad portion 40 and the tip of the third extending portion 43 is about 150 μm. The separation distance h at the fourth side 41d of the first extending portion is about 240 μm. In addition, the width | variety of 1st extending | stretching part-4th extending | stretching parts 41-44 is all about 10 micrometers.

<Example 2>
The light emitting element according to Example 2 has substantially the same structure as the light emitting element 200 according to Embodiment 2, and will be described with reference to FIG.

  As shown in FIG. 2, the light emitting device according to Example 2 has the arrangement of the first electrodes 40, 41, 44 and the second electrodes 50, 42, 43 in Example 1 (FIG. 1) in the center of the semiconductor layer 20. It has a structure rotated 90 ° around the part. For this reason, the length of one side of the semiconductor layer 20 and the relationship between the distances in the pad portions 40 and 50 and the extending portions 41, 42, 43, and 44 are the same as those in the first embodiment, and the description thereof is omitted.

<Comparative example>
As shown in FIG. 3, the light emitting device 300 according to the comparative example has substantially the same structure as that of Example 1 except that the planar shape of the semiconductor layer 20 (20a, 20b, 20c) is a square. In plan view, the length of one side of the semiconductor layer 20 is about 800 μm, and the area of the semiconductor layer 20 is the same as that of the first embodiment.

<Comparison of current density distribution>
Next, the current density distributions in the light emitting elements of Example 1, Example 2, and Comparative Example were each analyzed by simulation software using a finite element method. The results are shown in FIG. 4 (Example 1), FIG. 5 (Example 2) and FIG. 6 (Comparative example). In addition, FIG.4, FIG.5 and FIG.6 shows that a current density is so high that all are dark and light.

  As shown in FIGS. 4, 5, and 6, the light emitting device 100 of Example 1 and the light emitting device 200 of Example 2 are different from the light emitting device 300 of the comparative example in that the first pad portion and the second pad portion are different. Regions with high current density are reduced in the region between. Moreover, in the light emitting element 300 of the comparative example, a region having a low current density is biased toward the first pad portion side of the periphery of the semiconductor layer. On the other hand, in the light emitting element 100 of Example 1 and the light emitting element 200 of Example 2, regions with low current density are distributed in a well-balanced manner on both sides of the first pad portion and the second pad portion. Furthermore, in Example 1 in which the second pad part faces the side of the semiconductor layer, the degree of decrease in current density on the second pad part side is more relaxed than in Example 2 in which the corner part of the semiconductor layer faces. It can be seen that the bias of the current density distribution is improved.

<Comparison of forward voltage, light output and power conversion efficiency>
Next, in the light-emitting elements of Example 1, Example 2, and Comparative Example, a current of 65 mA was applied, and the values of forward voltage [V], light output [mW], and power conversion efficiency [%] were measured. In addition, the value of power efficiency WPE [%] can be calculated | required by Formula (1).

  These results are shown in Table 1.

  As shown in Table 1, the light-emitting element 100 of Example 1 and the light-emitting element 200 of Example 2 have good values with respect to the light-emitting element 300 of the comparative example, and particularly the light output and power conversion efficiency. The improvement is large, and it is considered that the light extraction efficiency of the light emitting element is improved.

  As mentioned above, although the light emitting element which concerns on this invention was concretely demonstrated by embodiment and an Example, the meaning of this invention is not limited to these description, and interprets widely based on description of a claim. It must be. Needless to say, various changes and modifications based on these descriptions are also included in the spirit of the present invention.

  The light emitting device according to the embodiment of the present invention is used as a light source for illumination, a backlight light source such as an LED display and a liquid crystal display device, a traffic light, an illumination switch, various sensors and various indicators, and other general consumer light sources. It can be suitably used.

100, 200, 300 Light emitting element 10 Substrate 20 Semiconductor layer 20a Second conductive type semiconductor layer 20b Active layer 20c First conductive type semiconductor layer 21c First semiconductor side 21f Second semiconductor side 30 Translucent electrode 40 First pad portion 41 First extending portion 41a First side 41b Second side 41c Third side 41d Fourth side 41e, 41f, 41g, 41h Corner portion 42 Second extending portion 43 Third extending portion 44 Fourth extending portion 50 Second pad portion 60 Protective film

Claims (17)

A semiconductor layer having a regular hexagonal shape in plan view, and a pair of positive and negative first and second electrodes provided on the semiconductor layer;
The first electrode includes a first pad portion and a first extending portion that extends from the first pad portion and is formed in a substantially rectangular shape,
A first side which is one of four sides constituting the first extending portion is opposed to any corner of the semiconductor layer;
The second electrode is a light-emitting element disposed inside the first extending portion.   The light emitting device according to claim 1, wherein the first pad portion is disposed on the first side of the first extending portion.   The light emitting device according to claim 1, wherein the first pad portion is disposed on a second side adjacent to the first side of the first extending portion. The second side of the first extending portion is opposed to a first semiconductor side which is a side adjacent to a side constituting the corner portion among six sides constituting the semiconductor layer,
The first side of the first extending portion is the first of the second semiconductor side facing the first semiconductor side and the end of the first semiconductor side near the first side. It is arranged outside the first straight line connecting the end on the side close to the side,
The third side of the first extending portion that faces the first side is an end of the first semiconductor side that is closer to the third side, and the third side of the second semiconductor side. The light emitting element of Claim 3 arrange | positioned outside the 2nd straight line which connects the edge part near the side. The second electrode includes a second pad portion and two second extending portions extending from the second pad portion along the first extending portion,
One of the second extending portions extends outside the first straight line along the first side of the first extending portion,
The light emitting device according to claim 4, wherein the other of the second extending portions extends outside the second straight line along the third side of the first extending portion.   The 4th edge which counters the 2nd edge of the 1st extension part has a separation area, and the 2nd pad part is arranged so that the separation area may be opposed. Light emitting element.   The shortest distance between the fourth side adjacent to the first side of the first extension part and the portion of the second extension part extending along the fourth side is the first distance of the first extension part. The light-emitting element according to claim 6, wherein the light-emitting element is longer than a shortest distance between a side and a portion of the second extending portion that extends along the first side.   The shortest distance between the fourth side adjacent to the third side of the first extension part and the portion of the second extension part extending along the fourth side is the first distance of the first extension part. The light-emitting element according to claim 6 or 7, wherein the light-emitting element is longer than a shortest distance between a side and a portion of the second extending portion that extends along the first side.   The shortest distance between the tip of the second extending portion extending along the first side of the first extending portion and the corner portion connecting the first side and the second side of the first extending portion is: 9. The light emitting device according to claim 5, wherein the light emitting element is longer than a shortest distance between the first side of the first extending portion and a portion of the second extending portion extending along the first side. .   The shortest distance between the tip of the second extending portion extending along the third side of the first extending portion and the corner connecting the third side and the second side of the first extending portion is: 10. The light emitting device according to claim 5, wherein the light emitting element is longer than a shortest distance between the third side of the first extending portion and a portion of the second extending portion extending along the third side. . The second electrode has a third extending portion that extends between the two second extending portions from the second pad portion,
The said 1st electrode has two 4th extending | stretching parts extended | stretched from the said 1st pad part to between the said 3rd extending | stretching part and two said 2nd extending | stretching parts, respectively. The light emitting element as described in one.   On the diagonal line of the semiconductor layer parallel to the second side of the first extending portion, the distance between the adjacent first extending portion and the second extending portion is the second extending portion and the fourth extending adjacent to each other. The light-emitting element according to claim 11, wherein the light-emitting element is shorter than the distance from the extending portion.   On the diagonal line of the semiconductor layer parallel to the second side of the first extension part, the distance between the third extension part and the fourth extension part is the second extension part and the fourth extension part adjacent to each other. The light emitting element of Claim 11 or 12 longer than a distance.   The shortest distance between the tip of the fourth extending portion and the portion of the second extending portion extending along the fourth side opposite to the second side of the first extending portion is the first extending portion. 14. The light emitting device according to claim 11, wherein the light emitting element is longer than a shortest distance between a fourth side and a portion of the second extending portion that extends along the fourth side of the first extending portion.   The shortest distance between the tip of the fourth extending portion and the portion of the second extending portion extending along the fourth side opposite to the second side of the first extending portion is the first pad portion and the The light emitting element according to claim 11, wherein the light emitting element is shorter than a shortest distance from a tip of the third extending portion.   The shortest distance between the tip end of the second extension portion and the second side of the first extension portion is the fourth side facing the tip end of the fourth extension portion and the second side of the first extension portion. The light emitting element according to claim 11, wherein the light emitting element is shorter than a shortest distance from a portion of the second extending portion extending along the line.   The light emitting device according to any one of claims 1 to 16, wherein each of the four corners constituting the first extending portion has a curved shape.

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