KR20170011823A - Light emitting device - Google Patents

Abstract

Provided is a light emitting device which can prevent a reflection electrode from being stripped. According to an embodiment of the present invention, disclosed is the light emitting device which comprises: a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer; a transparent electrode layer arranged on one side of the light emitting structure, and electrically connected to the second semiconductor layer; a plurality of protrusions arranged on one surface of the transparent electrode layer; and a reflection electrode layer arranged on one surface of the transparent electrode layer, and covering the plurality of protrusions.

Description

[0001] LIGHT EMITTING DEVICE [0002]

An embodiment relates to a light emitting element.

A light emitting device (LED) is a compound semiconductor device that converts electric energy into light energy. By controlling the composition ratio of the compound semiconductor, various colors can be realized.

The nitride semiconductor light emitting device has advantages of low power consumption, semi-permanent lifetime, fast response speed, safety, and environmental friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps. Accordingly, a light emitting diode backlight replacing a cold cathode fluorescent lamp (CCFL) constituting a backlight of an LCD (Liquid Crystal Display) display device, a white light emitting diode lighting device capable of replacing a fluorescent lamp or an incandescent lamp, And traffic lights.

The light emitting device may include a transparent electrode and a reflective electrode for applying power to the p-type semiconductor layer. However, there is a problem that the reflective electrode formed on the transparent electrode is peeled off in the heat treatment process at a high temperature, thereby decreasing the reliability.

The embodiment provides a light emitting element that can prevent the reflection electrode from peeling off.

A light emitting device according to an embodiment of the present invention includes a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer; A light transmitting electrode layer disposed on one side of the light emitting structure and electrically connected to the second semiconductor layer; A plurality of protrusions disposed on one surface of the transparent electrode layer; And a reflective electrode layer disposed on one surface of the transparent electrode layer and covering the plurality of protrusions.

The plurality of protrusions may include different metal layers.

The metal layer may include a first metal layer in contact with the light-transmitting electrode layer and a second metal layer disposed on the first metal layer.

The thickness of the first metal layer may be smaller than the thickness of the second metal layer.

The ratio of the thickness of the first metal layer to the thickness of the second metal layer may be from 1: 300 to 1:10.

The first metal layer may include at least one of Cr, Ti, and Ni, and the second metal layer may include at least one of Al, Au, Cu, Sn, Pb and Zn.

The plurality of protrusions may include an alloy region disposed at a boundary of the reflective electrode layer.

The area of the plurality of projections covering the light-transmitting electrode layer may be 15% or less of the total area of the light-transmitting electrode layer.

The light emitting device includes: a first electrode pad electrically connected to the first semiconductor layer; And a second electrode pad electrically connected to the reflective electrode layer.

The light emitting device may include a second insulating layer covering the reflective electrode layer.

The first electrode pad is electrically connected to the first semiconductor layer through the second insulating layer, the reflective electrode layer, the transparent electrode layer, and a part of the light emitting structure, and the second electrode pad penetrates the second insulating layer And may be electrically connected to the reflective electrode layer.

The light emitting device includes a contact electrode layer disposed between the first semiconductor layer and the first electrode pad, and the structure of the plurality of protrusions may be the same as the contact electrode layer.

According to the embodiment, it is possible to prevent the reflection electrode from peeling, thereby improving the reliability of the light emitting element.

The various and advantageous advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the course of describing a specific embodiment of the present invention.

1 is a conceptual diagram of a light emitting device according to an embodiment of the present invention,
Fig. 2 is an enlarged view of a portion A of Fig. 1,
3A and 3B are photographs showing a result of adhesion test between a conventional light emitting device and a light emitting device according to an embodiment,
4A to 4E are flowcharts for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the embodiments of the present invention are not intended to be limited to the specific embodiments but include all modifications, equivalents, and alternatives falling within the spirit and scope of the embodiments.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the embodiments, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In the description of the embodiments, in the case where one element is described as being formed "on or under" another element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

FIG. 1 is a conceptual view of a light emitting device according to an embodiment of the present invention. FIG. 2 is an enlarged view of a portion A of FIG. 1, FIGS. 3a and 3b show adhesion test results of a conventional light emitting device, It is a photograph showing.

1, the light emitting device of the embodiment includes a light emitting structure S disposed on a substrate 110, a pair of electrode pads 170 and 180 disposed on one side of the light emitting structure S, A plurality of electrode layers 161, 162 and 163 and insulating layers 151 and 152 disposed between the electrode pads 170 and 180 and the electrode pads 170 and 180, respectively.

The substrate 110 includes a conductive substrate or an insulating substrate. The substrate 110 may be a material suitable for semiconductor material growth or a carrier wafer. The substrate 110 may be formed of a material selected from the group consisting of sapphire (Al ₂ O ₃ ), SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge. The light extraction pattern 111 may be formed on the substrate 110. In this case, the substrate may be a patterned sapphire substrate (PSS).

A buffer layer (not shown) may be further provided between the first semiconductor layer 120 and the substrate 110. The buffer layer may mitigate lattice mismatch between the substrate 110 and the light emitting structure S provided on the substrate 110.

The buffer layer may be a combination of Group III and Group V elements or may include any one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. The buffer layer may be doped with a dopant, but is not limited thereto. The buffer layer can be grown as a single crystal on the substrate 110, and the buffer layer grown with a single crystal can improve the crystallinity of the first semiconductor layer 120 growing on the buffer layer.

The light emitting structure S includes a first semiconductor layer 120, an active layer 130, and a second semiconductor layer 140. In general, the light emitting structure S may be cut along with the substrate 110 and separated into a plurality of light emitting structures.

The first semiconductor layer 120 may be formed of a compound semiconductor such as group III-V or II-VI, and the first semiconductor layer 120 may be doped with a first dopant. The first semiconductor layer 120 may be a semiconductor material having a composition formula of In _{x 1} Al _{y 1} Ga _{1 -x1-y1} N (0? _{X1? 1} , 0 _{? Y1? 1} , 0? X1 + y1? GaN, AlGaN, InGaN, InAlGaN, and the like. The first dopant may be an n-type dopant such as Si, Ge, Sn, Se, or Te. When the first dopant is an n-type dopant, the first semiconductor layer 120 doped with the first dopant may be an n-type semiconductor layer.

The active layer 130 is a layer where electrons (or holes) injected through the first semiconductor layer 120 and holes (or electrons) injected through the second semiconductor layer 140 meet. As the electrons and the holes recombine, the active layer 130 transitions to a low energy level and can generate light having a wavelength corresponding thereto.

The active layer 130 may have any one of a single well structure, a multiple well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, Is not limited thereto.

The second semiconductor layer 140 is formed on the active layer 130 and may be formed of a compound semiconductor such as group III-V or II-VI group. The second semiconductor layer 140 may be doped with a second dopant . A second semiconductor layer 140 is a semiconductor material having a compositional formula of _{In x5 Al y2 Ga 1 -x5- y2} N (0≤x5≤1, 0≤y2≤1, 0≤x5 + y2≤1) or AlInN, AlGaAs , GaP, GaAs, GaAsP, and AlGaInP. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, or Ba, the second semiconductor layer 140 doped with the second dopant may be a p-type semiconductor layer.

An electron blocking layer (EBL) may be disposed between the active layer (130) and the second semiconductor layer (140). The electron blocking layer can block the flow of electrons supplied from the first semiconductor layer 120 to the second semiconductor layer 140 and increase the probability of recombination of electrons and holes in the active layer 130. [ The energy band gap of the electron blocking layer may be greater than the energy band gap of the active layer 130 and / or the second semiconductor layer 140.

The electron blocking layer may be formed of a semiconductor material having a composition formula of In _{x 1} Al _{y 1} Ga ₁ -x ₁ -y ₁ N (0? X _{1? 1} , 0? Y _{1? 1} , 0? X 1 + _{y 1? 1} ), for example, AlGaN, InGaN, InAlGaN, and the like, but is not limited thereto.

The light emitting structure S includes a through hole H formed in the second semiconductor layer 140 in the direction of the first semiconductor layer 120. The first insulating layer 151 may be formed on the side surface of the light emitting structure S and the through hole H. [ At this time, the first insulating layer 151 may expose one surface of the second semiconductor layer 140.

The light-transmitting electrode layer 161 may be disposed on one side of the second semiconductor layer 140. The transparent electrode layer 161 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO) ), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IrOx, RuOx, RuOx / ITO, Ni / IrOx / Au and Ni / IrOx / Au / ITO And it is not limited to these materials.

The plurality of protrusions 162 may be disposed on one surface of the light-transmitting electrode layer 161. The reflective electrode layer 163 is disposed on one surface of the transparent electrode layer 161 to cover the plurality of projections 162.

The reflective electrode layer 163 can reflect light emitted from the active layer 130. The reflective electrode layer 163 may be formed of any one of In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, Ni, Cu, and WTi, or an alloy thereof, and may be formed as a single layer or a multilayer, but is not limited thereto. For example, the reflective electrode layer 163 may be an Ag layer.

The second insulating layer 152 covers the side surface of the light emitting structure S and the reflective electrode layer 163.

The first electrode pad 170 may be electrically connected to the first semiconductor layer 120. Specifically, the first electrode pad 170 is electrically connected to the first semiconductor layer 120 through the second insulating layer 152, the reflective electrode layer 163, the light-transmitting electrode layer 161, and a part of the light- .

The second electrode pad 180 may be electrically connected to the second semiconductor layer 140 through the transmissive electrode layer 161 and the reflective electrode layer 163. The second electrode pad 180 may be electrically connected to the reflective electrode layer 163 through the second insulating layer 152.

Referring to FIG. 2, the light transmitting electrode layer 161 may be disposed on one surface 141 of the second semiconductor layer 140. A reflective electrode layer 163 is disposed on one surface of the translucent electrode layer 161, and a plurality of protrusions 162 may be disposed therebetween. The plurality of protrusions 162 can improve the adhesion between the transmissive electrode layer 161 and the reflective electrode layer 163.

The plurality of protrusions 162 may include a plurality of metal layers 162a and 162b. The metal layers 162a and 162b may include a first metal layer 162a contacting the light transmitting electrode layer 161 and a second metal layer 162b disposed on the first metal layer 162a.

The first metal layer 162a may be a metal having a similar coefficient of thermal expansion (CTE) of the transparent electrode layer 161 or capable of ohmic contact. For example, the first metal layer 162a may include at least one of Cr, Ti, and Ni.

The thickness of the first metal layer 162a may be thinner than the thickness of the second metal layer 162b. In one example, the thickness of the first metal layer 162a may be between 1 nm and 3 nm. When the thickness of the first metal layer 162a is 1 nm to 3 nm, the adhesion with the reflective electrode layer 163 can be improved while suppressing the reduction of the luminous flux.

The second metal layer 162b may be an alloyable material with the reflective electrode layer 163. That is, the melting point of the second metal layer 162b may be similar to the melting point of the reflective electrode layer 163. For example, the second metal layer 162b may include at least one of Al, Au, Cu, Sn, Pb and Zn.

The thickness of the second metal layer 162b may be 30 nm to 300 nm. When the thickness of the second metal layer 162b is less than 30 nm, it is difficult to have a sufficient bonding force with the reflective electrode layer 163. When the thickness exceeds 300 nm, there is a problem that the thickness of the reflective electrode layer 163 becomes thicker. Accordingly, the thickness ratio of the first metal layer 162a and the second metal layer 162b may be 1: 300 to 1:10.

For example, the combination of the first metal layer / the second metal layer may be varied as Cr / Al, Ti / Al, Ni / Au, and the like. In addition, the plurality of projections 162 may be composed of three or more metal layers. For example, the combination of the first metal layer / the second metal layer / the third metal layer may be Cr / Al / Ni, Ti / Al / Ni, Ni / Au /

The plurality of protrusions 162 may include an alloy region 162c formed at the boundary of the reflective electrode layer 163. That is, the alloying may be performed at the boundary between the plurality of protrusions 162 and the reflective electrode layer 163 in the heat treatment process. In one example, if the reflective electrode layer 163 comprises Ag and the second metal layer 162b of the protrusions 162 comprises Al, the alloy region may comprise an Ag / Al alloy. The plurality of projections 162 and the reflective electrode layer 163 can be combined by this alloy region.

The area where the plurality of projections 162 cover the light-transmitting electrode layer 161 may be 15% or less of the total area of the light-transmitting electrode layer 161. If the area covered by the plurality of protrusions 162 exceeds 15%, a part of the light emitted from the light-emitting structure S may be absorbed by the first metal layer 162a and the light flux may be reduced. The diameter and spacing of the plurality of projections 162 may be between 100 nm and 5 탆. This diameter and spacing can be advantageous for controlling the cover area to 15% or less.

3A, it can be seen that the peeling phenomenon does not occur even when the light emitting device according to the embodiment is heat-treated at 330 ° C. However, referring to FIG. 3B, it can be seen that the interface between the light-transmitting electrode layer 161 and the reflective electrode layer 163 is separated by the high-temperature environment in the conventional light emitting device, and the peeling phenomenon P occurs.

4A to 4E are flowcharts for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention.

4A to 4E, a method of manufacturing a light emitting device according to an embodiment includes forming a light emitting structure S on a substrate 110; Forming a light-transmitting electrode layer (161) and a plurality of protrusions (162) on a light-emitting structure (S) having a through-hole formed therein; Forming a reflective electrode layer (163) on the plurality of projections (162); And forming a first electrode pad 170 electrically connected to the first semiconductor layer 120 and a second electrode pad 180 electrically connected to the second semiconductor layer 140. [

4A, the step of forming the light-emitting structure S includes laminating a first semiconductor layer 120, an active layer 130, and a second semiconductor layer 140 on a substrate 110 in order, (S) can be formed. Thereafter, the light-emitting structure S is mesa-etched to form the through-holes H.

The light extraction pattern 111 may be formed on the substrate 110. In this case, the substrate 110 may be a PSS (Patterned Sapphire Substrate).

Referring to FIG. 4B, the first insulating layer 151 may be formed on the sides of the mesa-etched light-emitting structure S and the through holes H. At this time, the first insulating layer 151 may expose one surface 141 of the second semiconductor layer 140.

4C, the step of forming the light transmitting electrode layer 161 and the plurality of protrusions 162 may include forming the light transmitting electrode layer 161 on one surface of the second semiconductor layer 140 exposed by the first insulating layer 151, Can be formed.

The transparent electrode layer 161 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO) ), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IrOx, RuOx, RuOx / ITO, Ni / IrOx / Au and Ni / IrOx / Au / ITO And it is not limited to these materials.

Thereafter, the contact electrode 171 and the plurality of projections 162 can be formed on the bottom surface of the through hole H. At this time, the contact electrode 171 and the plurality of protrusions 162 may have the same structure. For example, the contact electrode and the protrusion 162 may include a first metal layer 162a and a second metal layer 162b. The first metal layer 162a may include at least one of Cr, Ti, and Ni, The first electrode 162b may include at least one of Al, Au, Cu, Sn, Pb, and Zn.

According to this structure, since the contact electrode 171 and the plurality of protrusions 162 can be formed at the same time, the process can be simplified. However, the present invention is not limited thereto, and the contact electrode 171 and the protrusion 162 may have different metal layers. In this case, after the contact electrode 171 is formed, a plurality of protrusions 162 may be separately formed.

Referring to FIG. 4D, a reflective electrode layer 163 can be formed on the plurality of protrusions 162. The reflective electrode layer 163 may be formed to a thickness of 200 nm to 400 nm. Accordingly, the reflective electrode layer 163 can cover the plurality of projections 162. [ Thereafter, the second insulating layer 152 may be formed thereon, and then a part thereof may be exposed.

The reflective electrode layer 163 can reflect light emitted from the active layer 130. The reflective electrode layer 163 may be formed of any one of In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, Ni, Cu, and WTi, or an alloy thereof, and may be formed as a single layer or a multilayer, but is not limited thereto. For example, the reflective electrode layer 163 may be an Ag layer.

Referring to FIG. 4E, forming the first electrode pad 170 and the second electrode pad 180 may include forming a first electrode pad 170 to be electrically connected to the first semiconductor layer 120, The second electrode pad 180 may be formed to be electrically connected to the second semiconductor layer 140. Solder pads may further be formed on the first electrode pad 170 and the second electrode pad 180, respectively.

The light emitting device of the embodiment further includes optical members such as a light guide plate, a prism sheet, and a diffusion sheet, and can function as a backlight unit. Further, the light emitting element of the embodiment can be further applied to a display device, a lighting device, and a pointing device.

At this time, the display device may include a bottom cover, a reflector, a light emitting module, a light guide plate, an optical sheet, a display panel, an image signal output circuit, and a color filter. The bottom cover, the reflector, the light emitting module, the light guide plate, and the optical sheet may form a backlight unit.

The reflector is disposed on the bottom cover, and the light emitting module emits light. The light guide plate is disposed in front of the reflection plate to guide light emitted from the light emitting module forward, and the optical sheet includes a prism sheet or the like and is disposed in front of the light guide plate. The display panel is disposed in front of the optical sheet, and the image signal output circuit supplies an image signal to the display panel, and the color filter is disposed in front of the display panel.

The lighting device may include a light source module including a substrate and a light emitting device of the embodiment, a heat dissipation unit that dissipates heat of the light source module, and a power supply unit that processes or converts an electric signal provided from the outside and provides the light source module . Further, the lighting device may include a lamp, a head lamp, or a street lamp or the like.

It will be apparent to those skilled in the art that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as defined in the appended claims. Will be apparent to those of ordinary skill in the art.

110: substrate
120: first semiconductor layer
130: active layer
140: second semiconductor layer
161: Transparent electrode layer
162: projection
163: reflective electrode layer
171: contact electrode

Claims (11)

A light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer;
A light transmitting electrode layer disposed on one side of the light emitting structure and electrically connected to the second semiconductor layer;
A plurality of protrusions disposed on one surface of the transparent electrode layer; And
And a reflective electrode layer disposed on one surface of the transparent electrode layer and covering the plurality of protrusions.
The method according to claim 1,
Wherein the plurality of protrusions comprise different metal layers.
3. The method of claim 2,
Wherein the metal layer includes a first metal layer in contact with the light-transmitting electrode layer and a second metal layer disposed on the first metal layer.
The method of claim 3,
Wherein the thickness of the first metal layer is thinner than the thickness of the second metal layer.
5. The method of claim 4,
Wherein the ratio of the thickness of the first metal layer to the thickness of the second metal layer is 1: 300 to 1:10.
The method of claim 3,
Wherein the first metal layer comprises at least one of Cr, Ti and Ni, and the second metal layer comprises at least one of Al, Au, Cu, Sn, Pb and Zn.
The method according to claim 1,
And the plurality of projections include an alloy region disposed at a boundary of the reflective electrode layer.
The method according to claim 1,
Wherein the area of the plurality of projections covering the light-transmitting electrode layer is 15% or less of the total area of the light-transmitting electrode layer.
The method according to claim 1,
A first electrode pad electrically connected to the first semiconductor layer; And
And a second electrode pad electrically connected to the reflective electrode layer.
10. The method of claim 9,
And a second insulating layer covering the reflective electrode layer,
Wherein the first electrode pad is electrically connected to the first semiconductor layer through the second insulating layer, the reflective electrode layer, the light transmitting electrode layer, and a part of the light emitting structure,
And the second electrode pad is electrically connected to the reflective electrode layer through the second insulating layer.
11. The method of claim 10,
And a contact electrode layer disposed between the first semiconductor layer and the first electrode pad,
The plurality of protrusions being the same as the contact electrode layer.

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