TWI418065B - Light emitting diode - Google Patents

Description

Light-emitting diode

The present invention relates to a light-emitting diode, and more particularly to an electrode design for a light-emitting diode.

For high-power light-emitting diodes, current spreading capability plays an important role. Especially in the application of high-power light-emitting diodes, under a large current density operation, uneven current distribution is extremely likely to cause burnt of the electrodes.

Therefore, the electrode design of the light-emitting diode focuses on evenly distributing the current. In the prior art, the design of the electrode metal extension line is used to effectively spread the current evenly. However, there is a problem of tip discharge at the end of the electrode metal extension line, which is liable to cause electrostatic breakdown and cause wafer damage. The electrode metal extension line can effectively help the current to diffuse, but it also causes light absorption problems, which in turn causes the problem of optical degradation. Therefore, the area of the metal extension line of the electrode is reduced to effectively reduce the light absorption problem. However, if the area of the electrode metal extension line is reduced, the thickness of the metal line must be increased to balance the current density, which results in higher production cost, and as the electrode metal line area shrinks, the problem of electrostatic breakdown and electrode burnout becomes more serious. .

In this technical field, there is a need for an electrode design of a light-emitting diode that can effectively help current diffusion and prevent electrostatic breakdown and electrode burnout without increasing electrode area and electrode thickness.

In view of the above, an embodiment of the present invention provides a light emitting diode, the light emitting diode includes a substrate, a light emitting structure disposed on the substrate, and a first electrode disposed on the first of the light emitting structures a transparent conductive layer disposed on a second surface of the light emitting structure; a second electrode disposed on the transparent conductive layer; a finger conductive layer adjacent to the second electrode and extending over The transparent conductive layer, wherein the finger conductive layer has an end portion away from the second electrode; an electrostatic protection layer is disposed between the finger conductive layer and the light emitting structure, and contacts the finger conductive layer The above end portion.

The following is a detailed description of the embodiments and examples accompanying the drawings, which are the basis of the present invention. In the drawings or the description of the specification, the same drawing numbers are used for similar or identical parts. In the drawings, the shape or thickness of the embodiment may be expanded and simplified or conveniently indicated. In addition, the components of the drawings will be described separately, and it is noted that the components not shown or described in the drawings are known to those of ordinary skill in the art, and in particular, The examples are merely illustrative of specific ways of using the invention and are not intended to limit the invention.

Embodiments of the present invention provide a light emitting diode having an electrode disposed between a finger conductive layer and a light emitting structure with an electrostatic protection layer and contacting an end portion of the finger conductive layer. Therefore, the light-emitting diode of the embodiment of the invention has the advantages of effectively helping current diffusion and preventing electrostatic breakdown and electrode burning. Fig. 1a is a top view of the light-emitting diodes 500a to 500b according to the embodiment of the present invention. 1b and 1c are respectively cross-sectional views of the light-emitting diodes 500a to 500b according to different embodiments of the present invention, which show different positions of the electrostatic protection layers. The light-emitting diode system shown in FIGS. 1a to 1c is a gallium nitride (GaN)-based blue light-emitting diode as an embodiment of the present invention. As shown in FIGS. 1a to 1c, the light emitting diode 500a or 500b of the embodiment of the present invention may include a substrate 200. In an embodiment of the invention, the substrate 200 may comprise a sapphire substrate. A light emitting structure 202 is disposed on the substrate 200. In an embodiment of the invention, a buffer layer (not shown) may be disposed between the substrate 200 and the light emitting structure 202. In an embodiment of the invention, the light emitting structure 202 may be composed of a semiconductor layer having a p-type n-type junction, which includes at least two electrically connected p-type semiconductor layers and an n-type semiconductor layer. And a light emitting semiconductor layer between the p-type semiconductor layer and the n-type semiconductor layer, and the semiconductor layer used for the light emitting structure 202 may include a material such as gallium nitride (GaN) or gallium indium nitride (GaInN). In an embodiment of the invention. In the present embodiment, the n-type semiconductor layer and the p-type semiconductor layer of the light emitting structure 202 are stacked along the direction of the surface of the vertical substrate 200, and a first surface 203 and a p-type semiconductor layer of the n-type semiconductor layer of the light emitting structure 202 are A second surface 205 is located on the same side of the light emitting structure 202 and is not coplanar, wherein the second surface 205 of the p-type semiconductor layer can be regarded as a light emitting surface.

As shown in FIGS. 1a-1c, a transparent conductive layer (TCL) 206 is disposed on the second surface 205 of the light emitting structure 202. In the present embodiment, the transparent conductive layer 206 is in direct contact with the p-type epitaxial layer of the light emitting structure 202. In an embodiment of the invention, the transparent conductive layer 206 has functions of high light transmittance, current spreading, and the like. In an embodiment of the invention, the transparent conductive layer 206 may comprise a thin metal conductive layer such as nickel-gold or a metal oxide conductive layer such as indium tin oxide (ITO).

As shown in FIGS. 1a to 1c, a first electrode 204 and a second electrode 208 are respectively disposed on a first surface 203 of the light emitting structure and a second surface 205, wherein the second electrode 208 is disposed on the transparent surface. On the conductive layer 206. In an embodiment of the invention, the first electrode 204 can be an n-type electrode electrically connected to the n-type epitaxial layer of the light-emitting structure 202, and the second electrode 208 can be a p-type electrode electrically connected to the light-emitting layer. The p-type epitaxial layer of structure 202.

As shown in FIGS. 1b to 1c, a finger-shaped conductive layer 210 is adjacent to the second electrode 208 and extends on the transparent conductive layer 206 along the surface of the transparent conductive layer 206. In an embodiment of the invention, the finger conductive layer 210 can be used as an extension of the second electrode 208, and the finger conductive layer 210 can be disposed to make the current of the light emitting diode 500a or 500b more uniform during operation. distributed. In an embodiment of the present invention, in order to consider not affecting the luminous efficiency of the light-emitting diode 500a or 500b, the finger-shaped conductive layer 210 is designed such that its width is much smaller than the width of the second electrode 208 and has a sufficient length to The current of the light-emitting diode 500a or 500b is effectively spread uniformly and the light absorption problem is effectively reduced. In an embodiment of the invention, the finger conductive layer 210 has an end portion 212 that is remote from the second electrode 208. However, the extending direction and shape of the finger conductive layer 210 are not limited to the embodiment.

As shown in FIGS. 1a-1c, an embodiment of the present invention provides an electrostatic protection layer 214a or 214b disposed between the finger conductive layer 210 and the light emitting structure 202 and contacting the end portion 212 of the finger conductive layer 210. . Since the end portion 212 of the finger-shaped conductive layer 210 having uniform current diffusion becomes the maximum electric field when the light-emitting diode 500a or 500b is operated at a high current density, a tip discharge is generated and the light-emitting diode is broken therefrom. The body 500a or 500b burns the electrode, and the light-emitting diode 500a or 500b is destroyed and cannot be used. The electrostatic protection layer 214a or 214b according to an embodiment of the present invention can effectively prevent the problem that the light-emitting diode 500a or 500b generates electrostatic breakdown at the end portion 212 under a large current density operation. In an embodiment of the invention, the electrostatic protection layer 214 or 214b may comprise a dielectric material. In the embodiment of the present invention, the electrostatic protection layer 214 or 214b may have different arrangement positions as long as the end portion 212 of the finger conductive layer 210 can be prevented from directly contacting the transparent conductive layer 206 or the light-emitting structure 202 under it.

As shown in FIG. 1b, in an embodiment of the present invention, the electrostatic protection layer 214a of the LED 500a may be disposed between the finger conductive layer 210 and the transparent conductive layer 206 and contact the end of the finger conductive layer 210. Section 212. In the embodiment as shown in FIG. 1b, the electrostatic protection layer 214a may extend from the end portion 212 of the finger conductive layer 210 toward the second electrode 208. In the embodiment of the present invention, the area of the electrostatic protection layer 214a may be much smaller than the area of the finger-shaped conductive layer 210, and the electrostatic protection layer 214a may have any shape as long as the edge of the electrostatic protection layer 214a is convexly exposed to the fingers. The edge of the end portion 212 of the layer 210 is sufficient.

As shown in FIG. 1c, in another embodiment of the present invention, the electrostatic protection layer 214b of the LED 500b can be disposed between the transparent conductive layer 206 and the light emitting structure 202, and the electrostatic protection layer 214b can be electrically conductive from the fingers. The end portion 212 of the layer 210 extends in the direction of the second electrode 208. The transparent conductive layer of the light-emitting diode 500b according to another embodiment of the present invention has an opening 218 as shown in FIG. 1c to expose the electrostatic protective layer 214b from the opening 218, and the end portion of the finger conductive layer 210. 212 is located in opening 218 to enable electrostatic protection layer 214b to contact end portion 212 of finger conductive layer 210. As shown in FIG. 1c, the edge of the electrostatic protection layer 214b also protrudes from the edge of the end portion 212 of the finger conductive layer 210.

The embodiment of the invention provides a light-emitting diode, wherein the electrode is designed to have an electrostatic protection layer between the end portion of the finger-shaped conductive layer and the light-emitting structure, which can effectively avoid the tip discharge of the finger-shaped conductive layer. Wear a light-emitting diode. Therefore, the light-emitting diode of the embodiment of the invention has the advantages of effectively helping current diffusion and preventing electrostatic breakdown and electrode burning. Therefore, the light-emitting diode of the embodiment of the invention can be widely applied to a high-power light-emitting diode, and the electrostatic protective layer can ensure the electrode can be prevented under high current density operation without increasing the electrode area and the electrode thickness. Burned down.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope is defined as defined in the scope of the patent application.

500a, 500b. . . Light-emitting diode

200. . . Substrate

202. . . Light structure

203. . . First surface

204. . . First electrode

205. . . Second surface

206. . . Transparent conductive layer

208. . . Second electrode

210. . . Finger conductive layer

212. . . End part

214a, 214b. . . Electrostatic protective layer

218. . . Opening

Fig. 1a is a top view of a light emitting diode according to an embodiment of the present invention.

1b and 1c are cross-sectional views of light emitting diodes of different embodiments of the present invention.

500a, 500b. . . Light-emitting diode

202. . . Light structure

203. . . First surface

204. . . First electrode

205. . . Second surface

206. . . Transparent conductive layer

208. . . Second electrode

210. . . Finger conductive layer

212. . . End part

214a, 214b. . . Electrostatic protective layer

Claims (10)

A light-emitting diode includes: a substrate; a light-emitting structure disposed on the substrate; a first electrode disposed on a first surface of the light-emitting structure; and a transparent conductive layer disposed on the light-emitting structure a second electrode disposed on the transparent conductive layer; a finger conductive layer adjacent to the second electrode and extending over the transparent conductive layer, wherein the finger conductive layer has a distance away from An end portion of the second electrode; and an electrostatic protection layer disposed between the finger conductive layer and the light emitting structure and contacting the end portion of the finger conductive layer, wherein the end of the finger conductive layer The portion and the light emitting structure are separated from each other by the electrostatic protection layer. The light-emitting diode of claim 1, wherein the electrostatic protection layer is disposed between the finger-shaped conductive layer and the transparent conductive layer. The light-emitting diode of claim 2, wherein an edge of the electrostatic protection layer protrudes from an edge of the end portion of the finger-shaped conductive layer. The light-emitting diode of claim 1, wherein the electrostatic protection layer is disposed between the transparent conductive layer and the light-emitting structure. The light-emitting diode of claim 4, wherein the transparent conductive layer has an opening such that the electrostatic protection layer is exposed from the opening, and the end portion of the finger-shaped conductive layer is located in the opening . The light-emitting diode according to claim 4, wherein the static An electrical protective layer extends from the end portion of the finger conductive layer toward the second electrode. The light-emitting diode of claim 6, wherein an edge of the electrostatic protection layer protrudes from an edge of the finger-shaped conductive layer. The light-emitting diode of claim 1, wherein the first surface and the second surface are on the same side of the light-emitting structure and the two are not coplanar. The light-emitting diode of claim 1, wherein the electrostatic protection layer comprises a dielectric material. The light-emitting diode of claim 1, wherein the substrate comprises sapphire.