WO2015096520A1

WO2015096520A1 - Light-emitting device

Info

Publication number: WO2015096520A1
Application number: PCT/CN2014/086725
Authority: WO
Inventors: 杨力勋; 蔡培崧; 徐宸科; 林素慧; 赵志伟; 黄少华
Original assignee: 厦门市三安光电科技有限公司
Priority date: 2013-12-23
Filing date: 2014-09-17
Publication date: 2015-07-02
Also published as: CN103700744A

Abstract

A photoelectric device (105). The photoelectric device (105) at least comprises: a light-emitting epitaxial lamination layer which at least comprises a first semiconductor layer (541) of a first conduction type, a second semiconductor layer (543) of a second conduction type and an active layer (542) which is sandwiched therebetween; a first electrode which is located above a surface of the first semiconductor layer (541) and comprises a bonding pad (521) and an extended electrode (522), wherein the extended electrode (522) is formed by extending the bonding pad (521) outwards; and a current barrier layer (532) which is located below the extended electrode (522), wherein the extension direction thereof is consistent with that of the extended electrode (522), but the edge thereof is not arranged in parallel with the edge of the extended electrode (522), so that a current is inclined to bypass but not to penetrate the current barrier layer (532) to be spread from the electrode to the device (105).

Description

Light emitting device

The present application claims priority to Chinese Patent Application No. 201310716962.2, the entire disclosure of which is hereby incorporated herein in

Technical field

The invention relates to a semiconductor light emitting device and belongs to the technical field of semiconductor device manufacturing.

Background technique

The core basic structure of a light emitting diode (LED) includes a p-type semiconductor layer (p region), an active layer (light emitting layer or light emitting portion), and an n-type semiconductor layer (n region). When the LED is subjected to a forward bias, the holes in the p region move toward the n region, the electrons in the n region move toward the p region, and the electrons and holes recombine in the active layer. In theory, most of the energy released by the recombination of electrons and holes is released in the form of light (radiation transition). Because LED has the advantages of low energy consumption, environmental protection, miniaturization and long life, it has broad market development prospects.

Summary of the invention

The present invention discloses a light emitting device structure in which at least one electrode structure and a current blocking layer for use with the electrode structure are included. The light emitting device, specifically comprising: a light emitting epitaxial stack, comprising at least: a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and an active layer sandwiched therebetween; the first electrode Located above the surface of the first semiconductor layer, including a pad and an extension electrode, the extension electrode is extended outward from the pad; a current blocking layer is located under the extension electrode, and an edge thereof and the extension electrode The edges are non-parallel, and the current tends to bypass rather than diffuse through the current blocking layer from the electrode to the device.

In some embodiments, the light emitting device comprises at least a stacked semiconductor structure and an electrode structure and a current blocking layer. The electrode structure includes at least one pad and one extension electrode, wherein the pad can be used to power the external circuit Connections, extension electrodes are used to facilitate the diffusion of current across the device. Meanwhile, on the entire extension electrode, the portion connected to the pad has the largest width in the direction orthogonal to the extending direction of the extension electrode, and the width of the extension electrode in the direction orthogonal to the extending direction thereof is from the position of the adjacent pad toward The ends of the extension electrodes are reduced such that the current densities across the cross-section of the entire extension electrode orthogonal to the direction of extension are approximately equal. At the same time, there is a current blocking layer at least below the extension electrode, and the current tends to bypass rather than diffuse from the electrode to the device through the current blocking layer. The extending direction of the current blocking layer coincides with the extension electrode, and the width of the current blocking layer in a direction orthogonal to the extending direction thereof decreases from the position of the adjacent pad to the end of the extension electrode.

In some embodiments, the light emitting device includes at least a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a light emitting layer between the two types of semiconductor layers. At least above the first semiconductor layer is an electrode that is in direct contact with the first semiconductor layer.

In some embodiments, the light emitting device includes at least a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a light emitting layer between the two types of semiconductor layers. There is at least one electrode above the first semiconductor layer, and at least one transparent conductive material is present between the electrode and the first semiconductor layer.

In some embodiments, the width of the current blocking layer in a direction orthogonal to the extending direction thereof is greater than the width of the extended electrode at the corresponding position, and the width difference between the two is reduced from the position of the adjacent pad to the end of the extended electrode. small.

In some embodiments, the width of the current blocking layer in a direction orthogonal to the extending direction thereof is smaller than the width of the extended electrode at the corresponding position, and the width difference between the two increases from the position of the adjacent pad to the end of the extended electrode. Big.

In some embodiments, the extension electrode includes a number of branches that are not directly connected to the pads. The width of the branch in a direction orthogonal to the direction in which it extends is reduced from the starting end to the end. And, at least under the main extension electrode, there is a current blocking layer, and the current tends to bypass and not diffuse from the electrode to the device through the current blocking layer, the extending direction of the current blocking layer is consistent with the main electrode of the electrode, and the current blocking layer is The width in the direction orthogonal to the direction of extension decreases from the position of the adjacent pad to the end of the extension electrode.

More preferably, a current blocking layer is also present under the extension electrode branch, and a width of the current blocking layer in a direction orthogonal to the extending direction thereof decreases from a position of the branch start end to an end of the branch, The width of the current blocking layer in an orthogonal direction to the direction in which it extends may be greater or smaller than the width of the extended electrode branch at the corresponding position.

DRAWINGS

Fig. 1 is a structural view of a known light emitting device.

Figure 2 is a cross-sectional view taken along line AA' of Figure 1.

Fig. 3 is a structural view of another known light emitting device.

Figure 4 is a cross-sectional view taken along line BB' of Figure 3.

Figure 5 is a structural diagram of a light emitting device in accordance with an embodiment of the present invention.

Figure 6 is a cross-sectional view taken along line CC' of Figure 5.

Figure 7 is a cross-sectional view taken along line DD' of Figure 5.

Figure 8 is a structural diagram of a light emitting device in accordance with another embodiment of the present invention.

Figure 9 is a structural view of a light emitting device in accordance with still another embodiment of the present invention.

Figure 10 is a cross-sectional view taken along line EE' of Figure 9.

Figure 11 is a structural view of a light emitting device according to still another embodiment of the present invention.

Symbol Description:

First semiconductor layers

141, 241, 341, 441, 541, 641;

Pads

121, 221, 321, 421, 521, 621;

Expansion electrodes

122, 222, 322, 422, 522, 622, 623;

Light emitting

portions

142, 242, 342, 542;

Second semiconductor layer

143, 243, 343, 543;

Current blocking layers

231, 232, 331, 332, 431, 432, 531, 532, 631, 632, 633;

Transparent conductive layer 551.

detailed description

The light-emitting diode can convert the externally injected current into a specific wavelength of light. Therefore, optimizing the current injection mode through proper electrode design is of great significance for improving the energy utilization efficiency and long-term operational stability of the device.

1 is a top plan view of a known light emitting device structure 101. The light emitting device includes a first semiconductor layer 141, a light emitting portion 142, a second semiconductor layer 143, and an electrode in direct contact with the first semiconductor layer 141. The electrode includes a pad 121 and an extension electrode 122. The pad may be connected to the external circuit through a wire or other conductor, and the extension electrode promotes diffusion of the current injected by the external circuit on the first semiconductor layer 141.

Figure 2 is a cross-sectional view taken along line AA' of Figure 1. When the device 101 is turned on with the external circuit, current is diffused to the first semiconductor layer 141 via the pad 121 and the extension electrode 122, and then injected into the light emitting portion 142 from the first semiconductor layer 141, which converts part of the electrical energy into light energy. And emitted, the final current flows into the second semiconductor layer 143 (143 can be directly connected to the external circuit), thus forming a complete loop.

In the device 101, the extension electrode 121 is a strip-like structure having a uniform width, so that as the current is diffused onto the first semiconductor layer 141, the current density of the extension electrode in a cross section orthogonal to the extending direction thereof is from the adjacent pad position toward The end of the extension electrode will continue to decrease. Thus, when the operating current is small, the current density of the extended electrode (especially the end position of the extended electrode) is low, resulting in low utilization efficiency of the electrode; when the operating current is large, the current density of the region adjacent to the extended electrode and the pad Too large, it is easy to cause material loss due to current overload, resulting in shortened device life. Further, as indicated by the dashed arrow in Fig. 2, the current tends to flow back to the external circuit from the semiconductor stacked structure directly under the electrode because such a current path is the shortest. In this case, on the one hand, the current is too small at a position away from the electrode, and the utilization efficiency for the light-emitting portion is too low; on the other hand, the light-emitting portion directly under the electrode generates more light, and when the light is emitted outward It is easier to be blocked by the electrodes, resulting in light loss.

3 and 4 are another known light emitting device structure 102, and Fig. 4 is a cross-sectional view taken along line BB' of Fig. 3. Different from FIG. 1, at least a current blocking layer 232 exists below the extension electrode 222. Preferably, the current blocking layer 231 is also present under the electrode pad 221.

Since the current tends to bypass rather than pass through the current blocking layer, the current blocking layer can better prevent current from directly injecting into the semiconductor stacked structure directly under the electrode, so that the current of the electrode is better diffused throughout the first semiconductor layer.

In FIG. 3, it can be seen that the edges of the extension electrode 222 and the current blocking layer 232 are parallel to each other. When current is injected, the electrode density at the electrode position adjacent to the pad has a maximum current density, and the current density on the extension electrode decreases from the adjacent pad position toward the end, so that the current density diffused from the extension electrode 222 to the first semiconductor 241 is from The adjacent pad also decreases toward the [z1] end. Therefore, the device 102 still exists. When the operating current is small, the current density of the extended electrode (especially the end position of the extended electrode) is low, resulting in low utilization efficiency of the electrode; when the operating current is large, the extended electrode is adjacent to the pad. The current density of the area is too large, which is easy to cause material loss due to current overload, resulting in a shortened service life of the device.

5, 6, and 7 are schematic views of the structure of an embodiment 103 in accordance with the present invention. The light emitting device includes at least a first semiconductor layer 341, a light emitting portion 342, a second semiconductor layer 344, and an electrode structure directly thereon. The electrode structure includes a pad 321 and an extension electrode 322. At least a current blocking layer 332 is present under the extension electrode 322. Preferably, a current blocking layer 331 is also present under the pads. In the present embodiment, the current blocking layer 332 extends in the same direction as the extension electrode 322, but the current blocking layer edge 332a is non-parallel to the edge 331a of the extension electrode. The width of the extension electrode 322 in the direction orthogonal to the extending direction thereof remains unchanged, and the current blocking layer 332 has the largest width at the position adjacent to the pad (ie, the starting end a) and is reduced in the extending direction (ie, the end b). Amplitude. With this design, although the extension electrode 322 has a higher potential at a portion adjacent to the pad, the resistance caused by the current blocking layer 332 is correspondingly increased, thereby increasing the diffusion of the entire extension electrode 322 toward the first semiconductor layer 341. Uniformity of current.

FIG. 8 is a block diagram showing another embodiment 104 in accordance with the present invention. The difference between the device 104 and the device 103 is that at the position adjacent to the pad 421, the extension electrode 422 has the largest width and the width is along with the solder. The disk distance increases as the distance increases. With this design, the width of the extension electrode 422 can be matched as closely as possible with the current intensity at the corresponding position, so that the current density across the cross section of the extension electrode 422 in the direction orthogonal to the extension direction remains substantially the same, thereby improving the electrode material. Utilize efficiency and increase the overall stability of the device. In FIG. 8, the width of the current blocking layer 432 in the direction orthogonal to the extending direction thereof is smaller than the width of the corresponding extended electrode from the position of the adjacent pad to the end of the extending direction. That is, at the position a, the difference between the expanded electrode width and the current blocking layer width is smaller than the difference between the expanded electrode width and the current blocking layer width at the position a.

9 and 10 are schematic views showing the structure of a current blocking layer 532 of the device 105, which is larger than the extension electrode 522, in accordance with still another embodiment of the present invention. As shown in FIG. 9, at the position adjacent to the pad 521, the extension electrode 522 and the current blocking layer 532 have the largest width, and the width decreases as the distance from the pad increases, but the reduction range of the current blocking layer 532 It is larger than the corresponding expansion electrode. That is, at the position a, the difference between the expanded electrode width and the current blocking layer width is greater than the difference between the expanded electrode width and the current blocking layer width at the position a. As shown in FIG. 10, a transparent conductive layer 551 is further present between the current blocking layer 532 and the

extension electrode

522, and 551 is present over the entire first semiconductor layer 541.

Figure 11 is a schematic view showing the structure of still another embodiment of the present invention. The difference between

devices

106 and 104 is that the extension electrode 622 also includes a plurality of branches 623. The starting end a of the branch 623 has the largest width and decreases toward the end b. Further, a current blocking layer 633 may be disposed under the branch extension electrode, and a width of the current blocking layer in a direction orthogonal to the extending direction thereof decreases from a position adjacent to the main extension electrode 632 toward a tip end of the branch.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. These improvements and retouchings should also be considered. It is the scope of protection of the present invention.

Claims

A light emitting device comprising:

The light emitting epitaxial laminate comprises at least: a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and an active layer sandwiched therebetween;

a first electrode, located above the surface of the first semiconductor layer, including a pad and an extension electrode, the extension electrode being extended outward from the pad;

a current blocking layer, located below the extension electrode, extending in a direction consistent with the extension electrode, but the edge is non-parallel to the edge of the extension electrode such that current tends to bypass rather than pass through the current blocking layer from the electrode Spread to the device.
A light emitting device according to claim 1, wherein said current blocking layer has a maximum width at a position adjacent to the pad, and a width decreases as the distance from the pad increases.
A light emitting device according to claim 1, wherein said spread electrode and current blocking layer have a maximum width at a position adjacent to the pad, and the width decreases as the distance from the pad increases However, the current blocking layer has a smaller reduction width than the corresponding expansion electrode.
A light emitting device according to claim 1, wherein a width of said current blocking layer in a direction orthogonal to the extending direction thereof is larger than a width of said expanding electrode in a direction orthogonal to the extending direction thereof at the corresponding position, The width difference between the two decreases from the position of the adjacent pad to the end of the extension electrode.
A light emitting device according to claim 1, wherein a width of said current blocking layer in a direction orthogonal to an extending direction thereof is smaller than a width of said expanding electrode in a direction orthogonal to a direction in which said extending electrode is located at a corresponding position, The width difference between the two increases from the position of the adjacent pad to the end of the extension electrode.
A light emitting device according to claim 1, wherein said extension electrode comprises a plurality of branches which are not directly connected to said pads.
A light emitting device according to claim 6, wherein a width of said branch in a direction in which it extends is decreased from a start end to a tip end.
A light emitting device according to claim 6, wherein a current blocking layer is present under said branch, and a width in an orthogonal direction to a direction in which it extends is smaller than a width of said extended electrode branch at a corresponding position.
A light emitting device according to claim 6, wherein a current blocking layer is present under said branch, and a width in a direction orthogonal to the extending direction thereof is larger than a width of said extended electrode branch at the corresponding position.
A light emitting device according to claim 8 or 9, wherein a width of said current blocking layer in a direction orthogonal to the extending direction thereof decreases from a position of said branch start end to an end of said branch .