JP2006351575A - Semiconductor light emitting device - Google Patents

Abstract

A semiconductor light-emitting element capable of achieving high luminance by improving light emission efficiency is provided.
In a semiconductor light emitting device, an n-type semiconductor layer is stacked on a substrate, an n-side electrode for bonding and a light-emitting layer are stacked on the n-type semiconductor layer, and a p-type is formed on the light-emitting layer. The semiconductor layer 5 is laminated, the p-type transparent electrode part 6 having light transmittance is laminated on the p-type semiconductor layer 5, and the p-side electrode 7 for bonding is laminated on the p-side transparent electrode part 6. Since the position of the light emitting layer 4 is located at the substantially central portion of the transparent electrode portion 3c, the reflective electrode layer 3b reflects the light that has entered the transparent electrode portion 3c obliquely and is directed downward. Is emitted to the side of the n-side electrode 3 while being reflected by the reflective electrode layer 3d. Therefore, the light emission efficiency can be improved, and the luminance of the semiconductor light emitting element 10 can be improved.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor light emitting device having a structure in which a semiconductor layer and a light emitting layer are stacked on a substrate.

  An example of a conventional semiconductor light emitting device is shown in FIG. As shown in FIG. 5, the semiconductor light emitting device 60 includes an n-type semiconductor layer 62 stacked on a sapphire insulating substrate 61 or a gallium nitride (GaN) conductive substrate, and contacts formed on the n-type semiconductor layer 62 with titanium. An n-side electrode 63 for bonding formed of gold and a light-emitting layer 64 are laminated through a layer 69, and a p-type semiconductor layer 65, a p-side transparent electrode 66 having light transmittance, and gold are formed on the light-emitting layer 64. The bonded p-side electrodes 67 for bonding are sequentially stacked. The p-side electrode and the n-side electrode are electrically connected to the outside by a wire 68.

Another conventional light emitting element is disclosed in Patent Document 1. As shown in FIG. 6, in the semiconductor light emitting device described in Patent Document 1, a gallium nitride buffer layer 51 is stacked on a sapphire insulating substrate 50, and an n-type contact layer 52 is stacked on the gallium nitride buffer layer 51. An n-type cladding layer 53, a light emitting layer 54, a p-type cladding layer 55, a p-type contact layer 56, and an n-type reverse tunneling layer 57 are laminated on the first surface of the n-type contact layer 52, and this n-type reverse tunneling layer A p-side transparent electrode 58 is sequentially laminated on 57. An n-side transparent electrode 59 made of the same material as the p-side transparent electrode 58 is also laminated on the second surface of the n-type contact layer 52. In the semiconductor light emitting device described in Patent Document 1, the p-side transparent electrode 58 and the n-side transparent electrode 59 are formed in one time by forming the p-side transparent electrode 58 and the n-side transparent electrode 59 with the same material. The manufacturing procedure can be simplified.
JP 2003-60236 A

  In the conventional semiconductor light emitting device 60 shown in FIG. 5, light emitted from the light emitting layer 64 of the semiconductor light emitting device 60 passes through the p-side transparent electrode 66 having light transmittance through the light emitting layer 64. It is emitted outside. However, the light traveling toward the n-side electrode 63 located on the side of the light emitting layer 64 is absorbed by the gold forming the n-side electrode 63. As a result, the light emission efficiency of the semiconductor light emitting device 60 is deteriorated by the amount absorbed by the n-side electrode 63, and the luminance is lowered.

  The n-side transparent electrode 59 of Patent Document 1 is formed of the same material as that of the p-side transparent electrode 58 in order to simplify the manufacturing procedure, and is not considered for improving the luminance.

  The semiconductor light emitting device may increase the current in order to improve the luminance, but there is a concern that other obstacles such as a heat problem may occur. Therefore, it is desirable to improve the light emission efficiency as much as possible.

  Therefore, an object of the present invention is to provide a semiconductor light emitting device capable of increasing the luminance by improving the light emission efficiency.

  In the semiconductor light emitting device of the present invention, an n-type semiconductor layer is stacked on a substrate, an n-side electrode and a light-emitting layer are stacked on the n-type semiconductor layer, a p-type semiconductor layer is stacked on the light-emitting layer, and the p-type In the semiconductor light emitting device in which the p-side electrode is stacked on the semiconductor layer, the n-side electrode has a transparent electrode portion that transmits light emitted from the light emitting layer to the side at a height where the light emitting layer is located. It is characterized by.

  According to the semiconductor light emitting device of the present invention, the n-side electrode has a transparent electrode portion that transmits light from the side of the light emitting layer at a height at which the light emitting layer is located, so that the n side electrode is positioned on the side of the light emitting layer. The light traveling toward the n-side electrode can pass through the transparent electrode portion and be emitted to the outside. Thereby, the light emission efficiency of the semiconductor light emitting device is increased, and a semiconductor light emitting device having high luminance can be obtained.

  In the first invention of the present application, an n-type semiconductor layer is stacked on a substrate, an n-side electrode and a light-emitting layer are stacked on the n-type semiconductor layer, a p-type semiconductor layer is stacked on the light-emitting layer, and a p-type semiconductor layer is formed on the p-type semiconductor layer. In the semiconductor light emitting device in which the p-side electrode is laminated, the n-side electrode has a transparent electrode portion that transmits light emitted from the light emitting layer to the side at a height where the light emitting layer is located. It is an element.

  The light traveling toward the n-side electrode located on the side of the light-emitting layer passes through the transparent electrode portion that transmits light emitted from the light-emitting layer formed at the height where the light-emitting layer is located at the n-side electrode. Is emitted outside. Therefore, the light emission efficiency of the semiconductor light emitting device can be improved, and a semiconductor light emitting device with high luminance can be obtained.

  According to a second invention of the present application, in the first invention of the present application, the transparent electrode portion is formed to be thicker than the thickness of the light emitting layer.

  Since the transparent electrode portion is formed to be thicker than the light emitting layer, the transparent electrode portion can transmit most of the light traveling from the side of the light emitting layer toward the transparent electrode portion, and can be emitted outside. Further, a semiconductor light emitting element with higher luminance can be obtained.

  According to a third invention of the present application, in the first or second invention of the present application, a light reflecting electrode layer is formed so as to sandwich the transparent electrode portion.

  Light incident obliquely to the transparent electrode portion from the side of the light emitting layer is reflected by the light reflecting electrode layers formed on the upper surface and the lower surface of the transparent electrode portion so as to sandwich the transparent electrode portion. Since the light can be emitted from the side, the luminance of the semiconductor light emitting element can be further improved.

  A fourth invention of the present application is characterized in that, in the first invention or the second invention of the present application, a light-reflecting electrode layer is formed only on a surface on the n-side semiconductor layer side of the transparent electrode portion.

  Since the light reflecting electrode layer is formed only on the surface of the transparent electrode portion on the n-side semiconductor layer side, the n-side semiconductor layer side of the light incident obliquely to the transparent electrode portion from the side of the light emitting layer The light-reflecting electrode layer reflects the light directed toward, and can be emitted outside from the surface of the n-side electrode opposite to the n-side semiconductor layer side, thereby further improving the luminance of the semiconductor light-emitting element. it can.

  A fifth invention of the present application is characterized in that, in the first invention or the second invention of the present application, the light reflecting electrode layer is formed only on a surface opposite to the n-side semiconductor layer side of the transparent electrode portion. And

  Since the light-reflecting electrode layer is formed only on the surface opposite to the n-side semiconductor layer side of the transparent electrode portion, n of the light incident obliquely to the transparent electrode portion from the side of the light-emitting layer Since the light reflecting electrode layer reflects light going to the side opposite to the side semiconductor layer side and can be emitted from the side of the n-side electrode, the luminance of the semiconductor light emitting element can be further improved.

(Embodiment 1)
Hereinafter, the semiconductor light emitting device in the first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view of a semiconductor light emitting device according to the first embodiment of the present invention. As shown in FIG. 1, in the semiconductor light emitting device 10 of this embodiment, an n-type semiconductor layer 2 is stacked on a substrate 1, and an n-side electrode 3 for bonding and a light-emitting layer 4 are stacked on the n-type semiconductor layer 2. The p-type semiconductor layer 5 is laminated on the light-emitting layer 4, the p-side transparent electrode portion 6 having optical transparency is laminated on the p-type semiconductor layer 5, and the p-side electrode 7 for bonding is attached to the p-side transparent electrode portion 6. It is a laminated one. The semiconductor light emitting device 10 of the present embodiment is a so-called face-up type light emitting device, and has a structure in which light is extracted from the entire p-side transparent electrode portion 6 having light transmittance.

  As the material of the substrate 1, a sapphire substrate that is an insulating material or a conductive GaN substrate is used.

  The n-type semiconductor layer 2 is formed by laminating GaN and AlGaN on the substrate 1. Note that a buffer layer formed of GaN or InGaN may be provided between the substrate 1 and the n-type semiconductor layer 2.

  The light emitting layer 4 is formed by laminating InGaN on the entire surface of the n-type semiconductor layer 2. The p-type semiconductor layer 5 is formed by laminating GaN on the entire surface of the light emitting layer 4. The light-emitting layer 4 and the p-type semiconductor layer 5 are formed by laminating InGaN to be the light-emitting layer 4 on the entire surface of the n-type semiconductor layer 2 and GaN to be the p-type semiconductor layer 5 on the entire surface of the InGaN. The n-type semiconductor layer 2 is formed by exposing a region for forming the n-side electrode 3 by etching. The light emitting layer 4 of this embodiment has a single layer structure. For example, the luminance can be further improved by forming a multi-quantum well structure in which at least a pair of InGaN type semiconductor layers and GaN type semiconductor layers are alternately stacked. it can.

  The p-side transparent electrode portion 6 is formed by laminating ITO (Indium Tin Oxide) or ZnO on the entire surface of the p-type semiconductor layer 5, and the light emitted from the light-emitting layer 4 and traveling upward is light transmissive. The light passes through the p-side transparent electrode portion 6 and is emitted to the outside of the semiconductor light emitting element 10. On the p-side transparent electrode portion 6, a p-side electrode 7 is formed by partially laminating Au or the like having good bonding properties. A wire 8 is bonded to the p-side electrode 7 to electrically connect the semiconductor light emitting element 10 to the outside.

  The n-side electrode 3 is formed in a region formed in the n-type semiconductor layer 2 by dry etching with a contact electrode 3a connected to the n-type semiconductor layer 2 made of Ti or the like, or a material having good light reflectivity such as Al. The reflective electrode layer 3b formed, the transparent electrode portion 3c formed of ITO or ZnO, the reflective electrode layer 3d formed of the same material as described above, or a material having a different reflectance, Au suitable for bonding, etc. The formed bonding electrodes 3e are sequentially stacked. Then, a wire 8 is bonded to the bonding electrode 3e, and the semiconductor light emitting element 10 is electrically connected to the outside. When the adhesion between the reflective electrode layer 3d and the bonding electrode 3e is poor, a barrier metal may be provided between the reflective electrode layer 3d and the bonding electrode 3e. Thereby, it can prevent that the bonding electrode 3e peels from the reflective electrode layer 3d.

  Here, the positional relationship between the light emitting layer 4 and the transparent electrode portion 3c of the n-side electrode 3 will be described. As shown in FIG. 1, the transparent electrode portion 3 c is located at the same height as the position where the light emitting layer 4 is formed in the n-side electrode 3, and this transparent electrode portion 3 c is located on the side from the light emitting layer 4. The light emitting layer 4 is formed thicker than the light emitting layer 4 so that the light emitted in the direction can be transmitted and emitted to the side of the semiconductor light emitting element 10. In the n-side electrode 3 of the present embodiment, the contact electrode 3a has a thickness of 0.1 μm, the reflective electrode layers 3b and 3d have a thickness of 0.05 μm, and the bonding electrode 3e has a thickness of 0.8 μm. . The thickness from the surface of the n-type semiconductor layer 2 where the n-side electrode 3 is formed to the lower end of the light-emitting layer 4 is 0.3 μm, the thickness of the light-emitting layer 4 is 0.06 μm, and the film of the p-type semiconductor layer 5 The thickness is 0.12 μm.

  Thus, by setting each film thickness as described above, the position of the light emitting layer 4 is positioned at the substantially central portion of the transparent electrode portion 3c. As shown in FIG. The reflective electrode layer 3b reflects the light that has entered obliquely to the lower side, and the light that is directed upward is emitted to the side of the n-side electrode 3 while being reflected by the reflective electrode layer 3d. Thereby, the brightness | luminance of the semiconductor light-emitting device 10 can be improved.

  In addition, the film thickness of each layer and each electrode of this embodiment is not restricted to the above-mentioned thing, but if the transparent electrode part 3c of the n side electrode 3 is located in the height where the light emitting layer 4 is located, In order to emit light from the light emitting layer 4 toward the n-side electrode 3 located on the side of the light emitting layer 4 with high efficiency, the film thickness of the transparent electrode portion 3c is set as much as possible. It is better to make it thick. Moreover, although it is desirable that the light emitting layer 4 is located in the approximate center of the transparent electrode part 3c, it is not limited to this.

(Embodiment 2)
Next, the semiconductor light emitting element in the second embodiment of the present invention will be described. FIG. 2 is a side view of the semiconductor light emitting element in the second embodiment of the present invention. In addition, about the thing of the structure similar to the semiconductor light-emitting device 10 in Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 2, in the semiconductor light emitting device 20 of the second embodiment, the n-type semiconductor layer 2 is formed of Ti or the like in the region where the n-side electrode 13 is formed in the n-type semiconductor layer 2 by dry etching. The contact electrode 13a to be connected to the electrode, the reflective electrode layer 13b formed of a material having a good light reflectivity such as Al, and the transparent electrode portion 13c formed of ITO or ZnO are sequentially laminated. The reflective electrode layer 3d of the n-side electrode 3 in Mode 1 is omitted, and the bonding electrode 13e is laminated on a part of the transparent electrode portion 13c. The wire 8 is bonded to the bonding electrode 13e and electrically connects the semiconductor light emitting element 20 to the outside.

  Also in the semiconductor light emitting device 20 of the second embodiment, the transparent electrode portion 13c of the n-side electrode 13 is located at the height where the light emitting layer 4 is located, as in the semiconductor light emitting device 10 of the first embodiment of the present invention. Therefore, the light traveling from the light emitting layer 4 toward the n-side electrode 13 positioned on the side of the light emitting layer 4 is transmitted through the transparent electrode portion 13 c and emitted to the side of the semiconductor light emitting element 20. In addition, as shown in FIG. 2, out of the light incident obliquely on the transparent electrode portion 13 c, the light directed downward is reflected by the reflective electrode layer 13 b and emitted above or to the side of the n-side electrode 13. In addition, light that has entered the transparent electrode portion 13c obliquely and passes upward is passed as it is and is emitted above the n-side electrode 13. Thereby, the brightness | luminance of the semiconductor light-emitting device 20 can be improved.

(Embodiment 3)
Next, a semiconductor light emitting element in the third embodiment of the present invention will be described. FIG. 3 is a side view of the semiconductor light emitting element in the third embodiment of the present invention. In addition, about the thing of the structure similar to the semiconductor light-emitting device 10 in Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 3, the semiconductor light emitting device 30 of the third embodiment is a so-called face-down type light emitting device, and the p-side light reflecting electrode layer 9 having light reflectivity is composed of the p-type semiconductor layer 5 and the p-side electrode. 16 is formed. Since the semiconductor light emitting element 30 of the third embodiment has a structure for extracting light from the substrate 1 side, the p-side electrode 16 does not need to be formed of a transparent electrode that allows light to pass through. In consideration of the bonding property for mounting by the Au bumps 17, it is desirable to form it with Au or the like.

  Light emitted from the light-emitting layer 4 of the semiconductor light-emitting element 30 of the third embodiment and traveling upward is emitted through the substrate 1. The light emitted from the light emitting layer 4 and traveling downward is reflected by the p-side light reflecting electrode layer 9 and travels upward or laterally. Also in the semiconductor light emitting device 30 of the third embodiment, the transparent electrode portion 3c of the n-side electrode 3 is positioned at the height where the light emitting layer 4 is located, as in the semiconductor light emitting device 10 of the first embodiment of the present invention. Therefore, light traveling from the light emitting layer 4 toward the n-side electrode 3 positioned on the side of the light emitting layer 4 passes through the transparent electrode portion 3 c and is emitted to the side of the semiconductor light emitting element 30. In addition, as shown in FIG. 3, the reflective electrode layer 3d reflects the light traveling downward to the transparent electrode portion 3c, and the reflective electrode layer 3b reflects the light traveling upward. Reflected and emitted to the side of the n-side electrode 3. Thereby, the brightness | luminance of the semiconductor light-emitting device 30 can be improved.

  As shown in FIG. 4, as another embodiment of the semiconductor light emitting device 30 in the third embodiment, a configuration in which the reflective electrode layer 3 b is omitted may be employed. Of the light incident obliquely from the light emitting layer 4 to the transparent electrode portion 3 c, the light directed downward is reflected by the reflective electrode layer 3 d and emitted to the side of the n-side electrode 3. Thereby, the brightness | luminance of the semiconductor light-emitting device 40 can be improved.

  INDUSTRIAL APPLICABILITY The present invention is useful as a semiconductor light emitting device having high luminance because the light emission efficiency can be improved in a semiconductor light emitting device having a structure in which a semiconductor layer and a light emitting layer are stacked on a substrate.

The side view of the semiconductor light-emitting device in the 1st Embodiment of this invention Side view of the semiconductor light emitting device in the second embodiment of the present invention Side view of a semiconductor light emitting device according to a third embodiment of the present invention The side view of the semiconductor light-emitting device in other embodiment of this invention Side view of conventional semiconductor light emitting device Side view of conventional semiconductor light emitting device

Explanation of symbols

1 substrate 2 n-type semiconductor layer 3 n-side electrode 3a, 13a contact electrode 3b, 3d, 13b reflective electrode layer 3c, 13c transparent electrode part 3e, 13e bonding electrode 4 light emitting layer 5 p-type semiconductor layer 6 p-side transparent electrode part 7 , 16 p-side electrode 8 wire 9 p-side light reflecting electrode layer 10, 20, 30 semiconductor light emitting element 17 bump

Claims (5)

An n-type semiconductor layer is stacked on the substrate, an n-side electrode and a light emitting layer are stacked on the n-type semiconductor layer, a p-type semiconductor layer is stacked on the light-emitting layer, and a p-side electrode is stacked on the p-type semiconductor layer. In the manufactured semiconductor light emitting device,
The n-side electrode is a semiconductor light-emitting element having a transparent electrode portion that transmits light emitted from the light-emitting layer to the side at a height at which the light-emitting layer is located. The semiconductor light emitting element according to claim 1, wherein the transparent electrode portion is formed thicker than a thickness of the light emitting layer. The semiconductor light emitting element according to claim 1, wherein a light reflecting electrode layer is formed so as to sandwich the transparent electrode portion. 3. The semiconductor light-emitting element according to claim 1, wherein a light-reflecting electrode layer is formed only on a surface of the transparent electrode portion on the n-side semiconductor layer side. 3. The semiconductor light-emitting element according to claim 1, wherein a light-reflecting electrode layer is formed only on a surface opposite to the n-side semiconductor layer side of the transparent electrode portion.

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