KR20080095452A - Light emitting device - Google Patents

Abstract

The invention is to improve the light emitting efficiency of a light emitting diode by designing a specific distribution doped with the multi quantum well structure of n-type impurity. A light emitting device(30) comprises an n-type semiconductor layer; a p-type semiconductor; a first region(35Ai) between the n-type and the p-type semiconductor layer, adjacent to the n-type semiconductor layer; a second region(35Bi) adjacent to the p-type semiconductor layer, a middle region(35Ci) between the first and the second region. The first and the second region are doped with the n-type impurity. The middle region has no n-type impurity or a lower concentration of n-type impurity than the first and second region.

Description

Light emitting element {LIGHT EMITTING DEVICE}

1 is a cross-sectional view of a conventional light emitting device 10.

2 is a cross-sectional view of another conventional light emitting device 20.

3 is a cross-sectional view of the light emitting device 30 according to the first embodiment of the present invention.

4 is a cross-sectional view of the light emitting device 40 according to the second embodiment of the present invention.

5 is a cross-sectional view of the light emitting device 50 according to the third embodiment of the present invention.

6 is a cross-sectional view of a light emitting device 60 according to the fourth embodiment of the present invention.

<Brief Description of Drawings>

10 light emitting element 11 substrate

12 buffer layer 13 n-type semiconductor layer

14 p-type semiconductor layer 15 light emitting layer

20 light emitting element 21 substrate

22 buffer layer 23 n-type semiconductor layer

24 p-type semiconductor layer 25 light emitting layer

30 light emitting element 31 substrate

32: buffer layer 33: n-type semiconductor layer

34 p-type semiconductor layer 35 light emitting layer

35Ai: Area close to n side 35Bi: Area close to p side

35Ci: intermediate region 35A1: first A layer

35A2: Second A layer 35A3: Third A layer

35B1: First B layer 35B2: Second B layer

35B3: 3rd B layer

40: light emitting element 41: substrate

42: buffer layer 43: n-type semiconductor layer

44 p-type semiconductor layer 45 light emitting layer

45Ai: Area close to n side 45Bi: Area close to p side

45Ci: middle region 45A1: first A layer

45A2: Second A layer 45A3: Third A layer

45B1: First B layer 45B2: Second B layer

45B3: 3rd B layer

50 light emitting element 51 substrate

52 buffer layer 53 n-type semiconductor layer

54 p-type semiconductor layer 55 light emitting layer

55Ai: Area close to n side 55Bi: Area close to p side

55Ci: intermediate region 55A1: first A layer

55A2: Second A layer 55A3: Third A layer

55B1: First B layer 55B2: Second B layer

55B3: Third B Layer

60 light emitting element 61 substrate

62 buffer layer 63 n-type semiconductor layer

64 p-type semiconductor layer 65 light emitting layer

65Ai: Area close to n side 65Bi: Area close to p side

65 Ci: Middle area 65A1: 1st A layer

65A2: Second A layer 65A3: Third A layer

65B1: First B layer 65B2: Second B layer

65B3: 3rd B layer

The present invention relates to a light emitting device, and more particularly to a light emitting device having a multi-quantum well structure.

Light emitting diodes (LEDs) are very important for solid-state devices with photoelectric conversion characteristics. In general, a light emitting layer is formed between two semiconductor layers having different electrical characteristics (p-type & n-type semiconductor layers). When a driving current is applied to the contact electrodes above the two semiconductor layers, electrons and holes of the two semiconductor layers are injected into the light emitting layer, and the light is combined by the light emitting layer to emit light. Is released through. In general, the light emitting layer is composed of a single quantum well structure (SQW) or a multi-quantum well structure (MQW), and compared with the single quantum well structure (SQW), the multi-quantum well structure (MQW) has a relatively high output capability. The reason is that even when the current is very weak, the light emitting layer of the multi-quantum well structure can convert current into light by passing through a small energy gap structure formed by overlapping a plurality of barrier layers and well layers.

1 shows a cross-sectional view of a conventional light emitting device 10. As shown in the drawing, there is a light emitting layer 15 having a multi-quantum well structure between one p-type nitride semiconductor layer 14 and one n-type nitride semiconductor layer 13, N-type impurities are not doped in the adjacent barrier layer, and n-type impurities are doped in all remaining barrier layers in the multi-quantum well structure. 2 is a cross-sectional view of another conventional light emitting device 20. As shown, there is a light emitting layer 25 of one multi-quantum well structure between one p-type nitride semiconductor layer 24 and one n-type nitride semiconductor layer 23 and an n-type nitride semiconductor of the multi-quantum well structure. Many barrier layers closest to layer 23 are doped with n-type impurities, while other barrier layers are not doped with n-type impurities.

An object of the present invention is to obtain a light emitting device having excellent electrical characteristics and improved luminous efficiency by changing the doping position of n-type impurities in a multi-quantum well structure.

The present invention provides a light emitting device including a substrate, an n-type nitride semiconductor layer, a p-type nitride semiconductor layer, a light emitting layer located between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer. Here, the light emitting layer has a multi-quantum well structure doped with n-type impurities, and the n-type impurity is doped in the multi-quantum well structure, particularly in a region close to the n-type semiconductor layer and a region close to the p-type semiconductor layer. The doped n-type impurity is not doped in the intermediate region, or the n-type impurity is doped to a concentration lower than that of both regions. In another embodiment, the structure is the same as described above, but one layer closest to the p-type nitride semiconductor layer in the multi-quantum well structure is not doped with n-type impurities.

Another object of the present invention to provide a light emitting device comprising a light emitting layer. The light emitting layer has a multi-quantum well structure in which a barrier layer and a well layer overlap each other and is doped with n-type impurities, and is located between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer. Here, the n-type impurities are located in the barrier layer in both regions close to the n-type impurity semiconductor layer and the p-type impurity semiconductor layer, and the intermediate region is not doped with n-type impurities or is lower than the concentration of impurities in both regions. Is doped with n-type impurities. In another embodiment, the structure is the same as described above, but the barrier layer closest to the multi-quantum well structure and the p-type nitride semiconductor layer does not dop the n-type impurity.

Hereinafter, with reference to the embodiment and the drawings will be described in detail for the present invention.

3 is a cross-sectional view of the light emitting device 30 according to the first embodiment of the present invention. The light emitting device 30 includes a substrate 31, a buffer layer 32, an n-type nitride semiconductor layer 33, a light emitting layer 35, and a p-type nitride semiconductor layer 34. Here, the light emitting layer 35 is a multi quantum well structure formed by overlapping a barrier layer and a well layer. In a preferred embodiment, the light emitting layer 35 has an area 35Ai (i = 1, 2, 3, ..., x) close to the n side, and an area 35Bi (i = 1, 2, 3 close to the p side). , ..., y, and intermediate region 35Ci (i = 1, 2, 3, ..., z). Here, the region 35Ai close to the n-side is formed of the first A layer 35A1, the second A layer 35A2, and the third A layer 35A3 close to the n-type nitride semiconductor layer 33. … And the like sequentially. The region 35Bi close to the p side includes the first B layer 35B1, the second B layer 35B2, and the third B layer 35B3 close to the p-type nitride semiconductor layer 34. … And the like sequentially. The first A layer 35A1, the third A layer 35A3, the first B layer 35B1, and the third B layer 35B3 are barrier layers, and the second A layer 35A2 and the second B layer ( 35B2) is the well layer. The odd layer is the barrier layer and the even layer is the well layer. In this embodiment, the n-type impurity doped into the light emitting layer 35 has a specific distribution, and the n-type impurity is doped in the region 35Ai close to the n-side and the region 35Bi close to the p-side (as shown). Doped the first A layer 35A1, the second A layer 35A2, the third A layer 35A3, the first B layer 35B1, the second B layer 35B2, and the third B layer 35B3). The intermediate region 35Ci is not doped with the n-type impurity or doped with the n-type impurity at a concentration lower than that of the region 35Ai near the n-side and the region 35Bi near the p-side.

4 is a cross-sectional view of the light emitting device 40 according to the second embodiment of the present invention. The light emitting device 40 includes a substrate 41, a buffer layer 42, an n-type nitride semiconductor layer 43, a light emitting layer 45, and a p-type nitride semiconductor layer 44. Here, the light emitting layer 45 is a multi-quantum well structure formed by overlapping the barrier layer and the well layer. In a preferred embodiment, the light emitting layer 45 has an area 45Ai (i = 1, 2, 3, ..., x) close to the n-side, an area 45Bi close to the p-side (i = 1, 2, 3). ..., Y, and the middle region 45Ci (i = 1, 2, 3, ..., z), wherein the region 45Ai near the n-side is the n-type nitride semiconductor layer 43. ... First A layer 45A1, second A layer 45A2, third A layer 45A3. … And the like sequentially. The region 45Bi close to the p side includes the first B layer 45B1, the second B layer 45B2, and the third B layer 45B3 closest to the p-type nitride semiconductor layer 44. … And the like sequentially. The first A layer 45A1, the third A layer 45A3, the first B layer 45B1, and the third B layer 45B3 are barrier layers, and the second A layer 45A2 and the second B layer 45B2. ) Is the well layer. That is, the odd layer is a barrier layer and the even layer is a well layer. In this embodiment, the n-type impurity doped into the light emitting layer 45 has a specific distribution, and the n-type impurity is doped in a portion 45Ai close to the n-side and 45Bi close to the p-side (not shown). As described above, the first A layer 45A1, the second A layer 45A2, the third A layer 45A3, the second B layer 45B2 and the third B layer 45B3 are doped), and the p-type nitride. The first B layer 45B1 closest to the semiconductor layer 44 is not doped with n-type impurities. The intermediate region 45Ci is not doped with the n-type impurity or doped with the n-type impurity at a concentration lower than that of the region 45Ai near the n-side and the region 45Bi near the p-side.

5 is a cross-sectional view of the light emitting device 50 according to the third embodiment of the present invention. The light emitting device 50 includes one substrate 51, a buffer layer 52, an n-type nitride semiconductor layer 53, a light emitting layer 55, and a p-type nitride semiconductor layer 54. Here, the light emitting layer 55 is a multi-quantum well structure formed by overlapping the barrier layer and the well layer. In a preferred embodiment, the light emitting layer has a region 55Ai (i = 1, 2, 3, ..., x) close to the n side, and a region 55Bi (i = 1, 2, 3, ..., close to the p side). y) and the intermediate region 55Ci (i = 1, 2, 3, ..., z). Here, the region 55Ai close to the n-side includes the first A layer 55A1, the second A layer 55A2, and the third A layer 55A3... Closest to the n-type nitride semiconductor layer 53. … And the like sequentially. The region 55Bi close to the p side includes the first B layer 55B1, the second B layer 55B2, and the third B layer 55B3 closest to the p-type nitride semiconductor layer 54. … And the like sequentially. The first A layer 55A1, the third A layer 55A3, the first B layer 55B1, and the third B layer 55B3 are barrier layers, and the second A layer 55A2 and the second B layer ( 55B2) is the well layer. The odd layer is the barrier layer and the even layer is the well layer. In this embodiment, the n-type impurity doped in the light emitting layer 44 has a specific distribution. n-type impurities are doped into each of the barrier layers in the region 55Ai close to the n-side and the region 55Bi close to the p-side (as shown in the drawing), the first A layer 55A1, the third A layer 55A3, Doping the first B layer 55B1 and the third B layer 55B3), and the intermediate region 55Ci has no n-type impurities, or is less than the concentration of the region 55Ai near the n-side and the region 55Bi near the p-side. There is a low concentration of n-type impurities.

6 is a cross-sectional view of a light emitting device 60 according to the fourth embodiment of the present invention. The light emitting element 60 includes a substrate 61, a buffer layer 62, an n-type nitride semiconductor layer 63, a light-emitting layer 65, and a p-type nitride semiconductor layer 64. Here, the light emitting layer 65 is a multi-quantum well structure formed by overlapping the barrier layer and the well layer. In a preferred embodiment, the light emitting layer 65 is an area 65Ai close to the n side (i = 1, 2, 3, ..., x), an area 65Bi close to the p side (i = 1, 2, 3). , ..., y, and the intermediate region 65Ci (i = 1, 2, 3, ..., z), and the region 65Ai close to the n-side is formed on the n-type nitride semiconductor layer 63. .. Nearest first A layer 65A1, second A layer 65A2, third A layer 65A3. … Etc., and the region 65Bi close to the p-side is sequentially the first B layer 65B1, the second B layer 65B2, and the third B layer 65B3 closest to the p-type impurity semiconductor layer 64. … … And the like sequentially. The first A layer 65A1, the third A layer 65A3, the first B layer 65B1, and the third B layer 65B3 are barrier layers, and the second layer 65A2 and the second B layer 65B2. ) Is the well layer. The odd layer is the barrier layer and the even layer is the well layer. In this embodiment, the n-type impurity doped into the light emitting layer 65 has a specific distribution, and some barrier layers in the region 65Ai near the n-side and the region 65Bi near the p-side dop the n-type impurity. (As shown, doping the first A layer 65A1, the third A layer 65A3, and the third B layer 65B3). The barrier layer closest to the p-type nitride semiconductor layer 64 (i.e., the first B layer 65B1) is not doped with n-type impurities, and the region 65Ai has no or near n-type impurities in the intermediate region 65Ci. ) And n-type impurities having a concentration lower than that of the barrier layer in the region 65Bi close to the p-side.

The doping of the n-type impurity in the present invention refers to the concentration of the element in the process of adding an element such as silicon (Si), germanium (Ge), tin (Sn), sulfur (S) or oxygen (O) to the thin film epitaxy. Refers to forming a nitride semiconductor thin film between 5 × 10 ¹⁶ and 1 × 10 ¹⁹ / cm ³ . Each layer that is not doped with other n-type impurities does not contain the element at all, and may contain the element at a very low concentration due to contaminants or diffusion in the manufacturing process, and the concentration may be about 1 × 10 ¹⁷ / less than ³ cm. In addition, the concentration of the n-type impurities doped in each layer is substantially the same or the region closer to the n-type semiconductor layer and the p-type semiconductor layer has a higher doping concentration.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

The present invention can not only obtain a device having excellent electrical characteristics through design for a specific doping distribution of the n-type impurity, but also effectively improve the luminous efficiency of the light emitting diode.

Claims (15)

n-type semiconductor layer; p-type semiconductor layer; And Located between the n-type semiconductor layer and the p-type semiconductor layer, a first region close to the n-type semiconductor layer, a second region close to the p-type semiconductor layer and between the first region and the second region And an intermediate region, wherein the first region and the second region are doped with n-type impurities, and the intermediate region has no n-type impurities or an n-type impurity having a concentration lower than that of the first and second regions. Light emitting layer having Light emitting device comprising a. The method of claim 1, The light emitting device is characterized in that the multi-quantum well structure. The method of claim 1, Wherein the n-type semiconductor layer is an n-type nitride semiconductor layer and the p-type semiconductor layer is a p-type nitride semiconductor layer. The method of claim 1, The n-type impurity includes at least one of silicon (Si), germanium (Ge), tin (Sn), sulfur (S) and oxygen (O). The method of claim 1, The concentration of the n-type impurities is substantially 5 × 10 ¹⁶ ~ 1 × 10 ¹⁹ / cm ³ Light emitting element which is in between. The method of claim 1, And the second region includes a plurality of semiconductor layers, and a semiconductor layer closest to the p-type semiconductor layer among the plurality of semiconductor layers is not doped with n-type impurities. The method of claim 1, And a concentration of the n-type impurity doped in the first region and the second region is substantially the same. According to claim 1, The closer to the n-type semiconductor layer and the p-type semiconductor layer, the higher the doping concentration of the n-type impurities, characterized in that the light emitting device. n-type semiconductor layer; p-type semiconductor layer; And A middle region located between the n-type semiconductor layer and the p-type semiconductor layer, a first region close to the n-type semiconductor layer, a second region close to the p-type semiconductor layer, and an intermediate region located between the first region and the second region An emission layer comprising an area; Including, The light emitting layer is formed by overlapping a plurality of barrier layers and a plurality of well layers, and barrier layers positioned in the first region and the second region of the plurality of barrier layers are doped with n-type impurities. Wherein said barrier layer is free of n-type impurities or whose concentration is lower than the concentration of said first region and said second region. The method of claim 9, Wherein the n-type semiconductor layer is an n-type nitride semiconductor layer, and the p-type semiconductor layer is a p-type nitride semiconductor layer. The method of claim 9, The n-type impurity comprises at least one of silicon (Si), germanium (Ge), tin (Sn), sulfur (S), oxygen (O). The method of claim 9, The concentration of the n-type impurities is substantially 5 × 10 ¹⁶ ~ 1 × 10 ¹⁹ / cm ³ Light emitting element which is between. The method of claim 9, And the second region includes a plurality of barrier layers, and a barrier layer closest to the p-type semiconductor layer among the plurality of barrier layers is not doped with n-type impurities. The method of claim 9, The concentration of n-type impurities doped into each barrier layer of the first region and the second region is substantially the same. The method of claim 9, The closer to the n-type semiconductor layer and the p-type semiconductor layer, the higher the doping concentration of the n-type impurities, characterized in that the light emitting device.

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