KR101897003B1 - Light emitting device - Google Patents

Abstract

The light emitting device according to the embodiment in which at least two light emitting diodes are connected in series is characterized in that the light emitting diode includes a light emitting structure including a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer, A first electrode and a second electrode on the second conductive type semiconductor layer, wherein the first electrode is electrically connected to the second electrode of the adjacent light emitting diode by two or more bridge electrodes.

Description

[0001] LIGHT EMITTING DEVICE [0002]

An embodiment relates to a light emitting element.

BACKGROUND ART Light emitting devices such as a light emitting diode (LD) or a laser diode using semiconductor materials of Group 3-5 or 2-6 group semiconductors are widely used for various colors such as red, green, blue, and ultraviolet And it is possible to realize white light rays with high efficiency by using fluorescent materials or colors, and it is possible to realize low energy consumption, semi-permanent life time, quick response speed, safety and environment friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps .

Therefore, a transmission module of the optical communication means, 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 element capable of replacing a fluorescent lamp or an incandescent lamp Diode lighting, automotive headlights, and traffic lights.

In order to fabricate a high output light emitting diode, a plurality of general light emitting diodes having a driving voltage of 2 to 4 V are connected in series. In this case, current spreading is not smooth in the same light emitting diode and adjacent light emitting diodes There is a problem that thermal damage is applied to the device and reliability is lowered.

The embodiment attempts to improve the reliability of the light emitting device.

The light emitting device according to the embodiment in which at least two light emitting diodes are connected in series is characterized in that the light emitting diode includes a light emitting structure including a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer, A first electrode and a second electrode on the second conductive type semiconductor layer, wherein the first electrode is electrically connected to the second electrode of the adjacent light emitting diode by at least two bridge electrodes.

The first electrode may include a first main electrode and two or more first branch electrodes branched from the first main electrode.

The second electrode may include a second main electrode and two or more second branch electrodes branched from the second main electrode.

The bridge electrode may electrically connect the first main electrode of the first electrode and the second main electrode of the second electrode of the adjacent light emitting diode.

The at least one first branch electrode of the first electrode may be positioned between two adjacent second branch electrodes of the second electrode of the same light emitting diode.

At least one second branch electrode of the second electrode may be located between two adjacent first branch electrodes of the first electrode of the same light emitting diode.

The light emitting diode may further include an insulating layer formed on at least a portion of the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer.

And an ohmic layer may be further formed between the second conductive semiconductor layer and the second electrode.

The light emitting structure may be formed on a substrate, and a light extracting structure may be formed on a surface of the substrate adjacent to the light emitting structure.

A second electrode pad may be formed on the second electrode of the light emitting diode located at the first end of the light emitting device among the two or more light emitting diodes.

A first electrode pad may be formed on the first electrode of the light emitting diode located at a second end opposite to the first end of the at least two light emitting diodes.

The two or more first branch electrodes of the first electrode may have a symmetrical structure with respect to each other.

The two or more second branch electrodes of the second electrode may have a symmetrical structure with respect to each other.

The insulating layer may electrically isolate between the adjacent two light emitting diodes and between the bridge electrode and the light emitting structure.

The first branch electrode of the first electrode and the second branch electrode of the second electrode may be alternately arranged.

At least a portion of the first branch electrode of the first electrode and the second branch electrode of the second electrode may be horizontally overlapped with each other.

The first main electrode of the first electrode and the second main electrode of the second electrode may be disposed to face each other.

The bridge electrode may be formed of a metal such as molybdenum (Mo), chromium (Cr), nickel (Ni), gold (Au), aluminum (Al), titanium (Ti), platinum (Pt), vanadium (V), tungsten (Pd), copper (Cu), rhodium (Rh) or iridium (Ir), or an alloy of the above metals.

According to the embodiment, not only the current spread in the same light emitting diode but also the current spreading between the adjacent light emitting diodes can be improved, so that the light emitting characteristic and the reliability of the light emitting element can be improved.

1 is a plan view of a light emitting device including two or more light emitting diodes connected in series according to an embodiment,
2 is an equivalent circuit diagram of light emitting diodes shown in FIG. 1,
FIG. 3 is a cross-sectional view of the light emitting device cut in the direction AA 'in FIG. 1,
4 is a cross-sectional view of the light emitting device cut in the direction BB 'in FIG. 1,
5 is an image profile of a light emitting device in which the intensity of light emitted when the number of bridge electrodes connecting adjacent two light emitting diodes is one and six is shown,
6 is a graph illustrating the intensity of light emitted from the light emitting device along the longitudinal direction,
7 is a view illustrating a light emitting device package including a light emitting device according to an embodiment,
8 is a view showing an embodiment of a headlamp in which a light emitting device according to an embodiment is disposed,
FIG. 9 is a view illustrating a display device in which a light emitting device package according to an embodiment is disposed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

In the description of the embodiment according to the present invention, in the case of being described as being formed "on or under" of each 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.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. Also, the size of each component does not entirely reflect the actual size.

FIG. 1 is a plan view of a light emitting device including two or more light emitting diodes connected in series according to an embodiment, FIG. 2 is an equivalent circuit diagram of light emitting diodes shown in FIG. 1, 4 is a cross-sectional view of the light emitting device cut in the direction BB 'in Fig. 1. Fig.

1 to 4, a light emitting device 100 according to an embodiment includes two or more light emitting diodes 110a to 110d connected in series, and each of the light emitting diodes 110a to 110d includes a first conductive semiconductor layer A light emitting structure 140 including a first conductive semiconductor layer 142, an active layer 144 and a second conductive semiconductor layer 146; first electrodes 150a to 150d on the first conductive semiconductor layer 142; And second electrodes 160a to 160d on the second conductive type semiconductor layer 146. [

1 to 4 illustrate that the light emitting device 100 includes four light emitting diodes 110a to 110d connected in series. However, there is no limitation on the number of light emitting diodes according to a desired driving voltage and fabrication method, The light emitting diodes may be connected in a combination of series and parallel.

FIG. 2 shows an equivalent circuit diagram of the light emitting diodes shown in FIG.

As described above, more or less than two light emitting diodes may be connected in series or in series and in a combination manner to be included in one light emitting device.

The light emitting diodes 110a to 110d include LEDs (Light Emitting Diodes) using semiconductor layers of a plurality of compound semiconductor layers, for example, Group III-V elements, and LEDs emit light such as blue, Or may be a UV LED. The emitted light of the LED may be implemented using various semiconductors, but is not limited thereto.

The light emitting structure 140 may be formed using a metal organic chemical vapor deposition (MOCVD) method, a chemical vapor deposition (CVD) method, a plasma enhanced chemical vapor deposition (PECVD) method, (MBE), hydride vapor phase epitaxy (HVPE), or the like, but the present invention is not limited thereto.

The first conductive semiconductor layer 142 may be formed of a semiconductor compound, for example, a compound semiconductor such as a group III-V element or a group II-VI element. The first conductive type dopant may also be doped. When the first conductive semiconductor layer 146 is an n-type semiconductor layer, the first conductive dopant may include Si, Ge, Sn, Se, and Te as an n-type dopant. In addition, when the first conductive semiconductor layer is a p-type semiconductor layer, the first conductive dopant may include Mg, Zn, Ca, Sr, and Ba as a p-type dopant, but is not limited thereto.

The first conductive semiconductor layer 142 includes a semiconductor material having a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) can do. The first conductive semiconductor layer 122 may be formed of one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP and InP.

A roughness or a pattern may be formed on the upper surface of the first conductivity type semiconductor layer 142 to improve light extraction efficiency.

The active layer 144 is a layer in which electrons and holes meet each other to emit light having energy determined by an energy band inherent in the active layer (light emitting layer) material.

The active layer 144 may be formed of at least one of a single well structure, a multi-well structure, a quantum-wire structure, or a quantum dot structure. For example, the active layer 144 may be formed with multiple quantum well structures by injecting trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) But is not limited thereto.

The well layer / barrier layer of the active layer 144 may be formed of any one or more pairs of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) But are not limited thereto. The well layer may be formed of a material having a band gap lower than the band gap of the barrier layer.

A conductive clad layer (not shown) may be formed on and / or below the active layer 144. The conductive clad layer may be formed of a semiconductor having a band gap wider than the band gap of the barrier layer of the active layer. For example, the conductive clad layer may comprise GaN, AlGaN, InAlGaN or a superlattice structure. Further, the conductive clad layer may be doped with n-type or p-type.

The second conductive semiconductor layer 146 may be formed of a semiconductor compound, for example, a group III-V compound semiconductor doped with a second conductive dopant. The second conductivity type semiconductor layer 142 has a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) Semiconductor material. When the second conductive semiconductor layer 146 is a p-type semiconductor layer, the second conductive dopant may include, but is not limited to, Mg, Zn, Ca, Sr, or Ba as a p-type dopant. In addition, when the second conductive semiconductor layer 146 is an n-type semiconductor layer, the second conductive dopant may include Si, Ge, Sn, Se, or Te as an n-type dopant, but is not limited thereto .

In the present embodiment, the first conductive semiconductor layer 142 may be an n-type semiconductor layer, and the second conductive semiconductor layer 146 may be a p-type semiconductor layer. Alternatively, the first conductive semiconductor layer 142 may be a p-type semiconductor layer, and the second conductive semiconductor layer 146 may be an n-type semiconductor layer. Also, an n-type semiconductor layer (not shown) may be formed on the second conductive semiconductor layer 146 when the semiconductor having the opposite polarity to the second conductive type, for example, the second conductive semiconductor layer is a p-type semiconductor layer . Accordingly, the light emitting structure may have any one of an n-p junction structure, a p-n junction structure, an n-p-n junction structure, and a p-n-p junction structure.

The light emitting structure 140 is grown on the substrate 120.

The substrate 120 supports the light emitting structure 140, and may be a conductive substrate or an insulating substrate. Further, it can be formed of a material having high electrical conductivity and high thermal conductivity. For example, the substrate 120 may be a substrate having a predetermined thickness and may be formed of a material selected from the group consisting of molybdenum (Mo), silicon (Si), tungsten (W), copper (Cu), and aluminum (Au), copper alloy (Cu Alloy), nickel (Ni), copper-tungsten (Cu-W), carrier wafers (e.g., GaN, Si, Ge a, GaAs, ZnO, SiGe, SiC , SiGe, Ga 2 O 3 , etc.) or a conductive sheet or the like may optionally be included.

A light extraction structure (not shown) such as a concavo-convex structure may be formed on the surface of the substrate 120 where the light emitting structure 140 is located.

Light generated in the light emitting structure 140 is diffused in the light extracting structure and is emitted to the outside of the light emitting diode, so that light extraction efficiency of the light emitting device can be improved.

A buffer layer 130 may be grown between the light emitting structure 140 and the substrate 120 to mitigate the difference in lattice mismatch and thermal expansion coefficient of the material. The material of the buffer layer may be at least one of Group III-V compound semiconductor such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. An undoped semiconductor layer may be formed on the buffer layer, but the present invention is not limited thereto.

The first electrodes 150a to 150d (150a to 150d) are formed on the first conductive type semiconductor layer 142 exposed by mesa etching a part of the second conductive type semiconductor layer 146, the active layer 144 and the first conductive type semiconductor layer 142 Is formed.

In addition, second electrodes 160a to 160b are formed on the second conductive type semiconductor layer 146. [

The first electrodes 150a to 150d and the second electrodes 160a to 160b may be formed of a metal such as molybdenum (Mo), chrome (Cr), nickel (Ni), gold (Au), aluminum (Al) (Pt), vanadium (V), tungsten (W), lead (Pd), copper (Cu), rhodium (Rh) or iridium (Ir) Or may be formed in multiple layers.

The ohmic layer 170 may be formed between the second conductive type semiconductor layer 146 and the second electrodes 160a to 160b. When the second conductivity type semiconductor layer 146 is a p-type semiconductor layer, the ohmic layer 170 may improve the ohmic characteristics because the impurity doping concentration is low and the contact resistance is high, And is not necessarily formed.

The ohmic layer 170 may be made of a transparent conductive layer and a metal. For example, ITO (indium tin oxide), IZO (indium zinc oxide), IZTO (indium zinc tin oxide), IZO ), IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON TiO 2, Ag, Ni, Cr, Ti, Al, Rh, ZnO, IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt, Au, and Hf.

Referring to FIG. 1, the first electrodes 150a to 150d may include a first main electrode 152 and two or more first branch electrodes 154 branched from the first main electrode 152 . The two or more first branch electrodes 154 may be formed to have a symmetrical structure with respect to each other.

The second electrodes 160a to 160d may include a second main electrode 162 and two or more second branch electrodes 164 branched from the second main electrode 162. [ Likewise, the two or more second branch electrodes 164 may be formed to have a symmetrical structure with respect to each other.

In the same light emitting diode, the first main electrode 152 of the first electrode and the second main electrode 162 of the second electrode may be arranged to face each other.

At least a part of the first branch electrode 154 of the first electrode and the second branch electrode 164 of the second electrode may be horizontally overlapped with each other. In FIG. 1, the first branch electrode 154 and the second branch electrode 164 are horizontally overlapped with each other by a constant width indicated by W in an example.

In the same light emitting diode, the first branch electrode 154 of the first electrode and the second branch electrode 164 of the second electrode may be alternately arranged.

As can be seen in FIG. 1, in the same light emitting diode, at least one first branch electrode 154 of the first electrode may be located between two adjacent second branch electrodes 164 of the second electrode. Likewise, at least one second branch electrode 164 of the second electrode may be located between adjacent two first branch electrodes 154 of the first electrode.

FIG. 1 illustrates an example in which the second electrodes 160a to 160d surround the first electrodes 150a to 150d. Therefore, the two second branch electrodes 164, which are located at the outermost portions, Electrodes 154 are not shown.

In one light emitting diode, a first electrode 150a-150d including a first main electrode 152 and two or more first branch electrodes 154, a second main electrode 162, The current can be evenly dispersed over the entire surface of the light emitting diode compared with the conventional electrode pattern without the branch electrode by disposing the second electrodes 160a to 160d including the light emitting diodes 164, Can be improved.

The first electrodes 150a to 150d are electrically connected to the second electrodes 160a to 160d of the adjacent light emitting diodes by the bridge electrode 175. [

1, for example, the first electrode 150a of the light emitting diode 110a is electrically connected to the second electrode 160b of the adjacent light emitting diode 110b by the bridge electrode 175, The first electrode 150b of the diode 110b is electrically connected to the second electrode 160c of the adjacent light emitting diode 110c by the bridge electrode 175 and electrically connected to the first electrode 150c of the light emitting diode 110c, May be electrically connected to the second electrode 160d of the adjacent light emitting diode 110d.

The first electrode of the light emitting diode and the second electrode of the adjacent light emitting diode may be electrically connected to each other by two or more bridge electrodes 175.

In FIG. 1, two adjacent light emitting diodes are illustrated as electrically connected to each other by six bridge electrodes.

The bridge electrode 175 may electrically connect the first main electrode 152 of the first electrode of the light emitting diode and the second main electrode 162 of the second electrode of the adjacent light emitting diode.

For example, the bridge electrode 175 is connected to the first main electrode 152 of the first electrode 150a of the light emitting diode 110a and the second main electrode of the second electrode 160b of the light emitting diode 110b adjacent to the first main electrode 152 162 between the first main electrode 152 of the first electrode 150b of the light emitting diode 110b and the second main electrode 162 of the second electrode 160c of the light emitting diode 110c adjacent thereto, The first main electrode 152 of the first electrode 150c of the light emitting diode 110c and the second main electrode 162 of the second electrode 160d of the adjacent light emitting diode 110d can be electrically connected .

By arranging two or more bridge electrodes between two adjacent light emitting diodes, current can be evenly spread over the entire light emitting element, as compared with connecting to one bridge electrode, so that the operating voltage of the light emitting element can be reduced.

Since the operating voltage of the light emitting device decreases, the WPE (Wall Plug Efficiency), which is a ratio of the input power of the electric energy applied to the light emitting device to the output power of the emitted light energy, may increase. In addition, the thermal damage of the light emitting element is reduced, so that the reliability of the entire light emitting element can be improved.

The bridge electrode 175 may be formed of the same material as the first electrodes 150a to 150d or the second electrodes 160a to 160d such as molybdenum (Mo), chromium (Cr), nickel (Ni) (Au), aluminum (Al), titanium (Ti), platinum (Pt), vanadium (V), tungsten (W), lead (Pd), copper (Cu), rhodium One metal or an alloy of these metals.

4, an insulating layer 180 is formed on the side surfaces of the first conductive semiconductor layer 142, the active layer 144, and the second conductive semiconductor layer 146 of the light emitting diodes 110a to 110d .

4 is a cross-sectional view of a light emitting diode including a first conductivity type semiconductor layer 142, an active layer 144, and a second conductivity type semiconductor layer 142, which start from a part of the upper surface of the first conductivity type semiconductor layer 142 of the light emitting diode, And an insulating layer 180 extending to the side surface of the two-conductivity type semiconductor layer 146. [

The insulating layer 180 protects the light emitting diode and electrically isolates the adjacent two light emitting diodes from each other to prevent an electrical short circuit and also prevents an electrical short between the bridge electrode 175 and the light emitting structure 140 .

The insulating layer 180 may be made of a nonconductive oxide or nitride. For example, the insulating layer 180 may include a silicon oxide (SiO ₂ ) layer, an oxide nitride layer, and an aluminum oxide layer.

The light emitting device 100 includes two or more light emitting diodes 110a to 110d connected in series and the second electrode of the light emitting diode 110a located at the first end 100a of the light emitting device 100 among the two or more light emitting diodes 100a, The second electrode pad 168 may be positioned on the first electrode portion 160a of the light emitting device 100 and the first electrode 100a of the light emitting diode 110d located on the second end portion 100d opposite to the first end portion 100a of the light emitting device 100, The first electrode pad 158 may be positioned on the first electrode pad 150d.

For example, referring to FIG. 1, a second electrode 160a of a light emitting diode 110a located at a first end 100a of the light emitting device 100 among two or more light emitting diodes 100a, The first electrode 150d of the light emitting diode 110d located at the second end portion 100d opposite to the first end portion 100a of the light emitting device 100 A first electrode pad 158 may be positioned on the first main electrode 152.

That is, the first electrode pad and the second electrode pad are located on the first electrode of the light emitting diode on one side of the light emitting device and on the second electrode of the light emitting diode on the other side of the light emitting device, The pad and the second electrode pad may be connected to an external electrode (not shown) through a wire to supply current to the light emitting device.

Table 1 below shows, by way of example, the results of evaluating the integral spheres when the number of bridge electrodes connecting two adjacent light emitting diodes is one and six.

Chip Size (number of bridges) IF (mA) VF (V) Po (mW) WPE (%) △ Po VF 1500 * 1500 (6) 80 11.94 366.5 38.37% 100.37% -0.23 1500 * 1500 (1) 80 12.17 365.1 37.50% 100.00% -

As a result of applying a current of 80 mA to two light emitting devices having different sizes and the same number of bridge electrodes connecting adjacent two light emitting diodes, as shown in Table 1, in the light emitting device using six bridge electrodes, ) Was measured as small as 0.23 V, power increased by 0.37%, and WPE also rose by 0.87%.

That is, as described above, it is confirmed that the degree of current spreading is improved over the entire light emitting device by arranging two or more bridge electrodes.

FIG. 5 is an image profile of a light emitting device in which the intensity of light emitted when the number of bridge electrodes connecting adjacent two light emitting diodes is one and six is compared, and FIG. 6 is an image profile of a light emitting device As compared with the case of the second embodiment.

5, when the image profile is close to the purple color (0), when the intensity of the light is weak and when the image profile is close to the red color (100), the intensity of the light Can be considered to be counted.

Referring to FIG. 5, it can be seen that the luminous intensity of the light emitting device having six bridge electrodes when the current of 20 mA is applied is higher than that of the light emitting device having only one bridge electrode. , And the distribution of color is uniform, which shows that the current spreading degree is also improved.

It can be seen that when the low current of 10 uA is applied, the luminous intensity of light is larger and the current spreading degree is also improved as compared with the case where the number of bridge electrodes is six.

Referring to FIG. 6, when the abscissa of the graph is the length of the light emitting device and the ordinate is the intensity of the emitted light, in the case of the light emitting device having one bridge electrode, the peak of the light intensity is larger than the six light emitting devices. It can be seen that these six individual light emitting devices can evenly distribute the current over the entire length of the light emitting device.

7 is a view illustrating an embodiment of a light emitting device package including a light emitting device according to an embodiment.

The light emitting device package 300 according to the embodiment includes a body 310 having a cavity formed therein, a first lead frame 321 and a second lead frame 322 provided on the body 310, The light emitting device 100 according to the above-described embodiments, which is installed to be electrically connected to the first lead frame 321 and the second lead frame 322, and a molding part 340 formed in the cavity.

The body 310 may include a silicon material, a synthetic resin material, or a metal material. When the body 310 is made of a conductive material such as a metal material, an insulating layer is coated on the surface of the body 310 to prevent an electrical short between the first and second lead frames 321 and 322 .

The first lead frame 321 and the second lead frame 322 are electrically separated from each other and supply current to the light emitting device 100. The first lead frame 321 and the second lead frame 322 may increase the light efficiency by reflecting the light generated from the light emitting device 100. The heat generated from the light emitting device 100 To the outside.

The light emitting device 100 may be mounted on the body 310 or may be mounted on the first lead frame 321 or the second lead frame 322. The first lead frame 321 and the light emitting element 100 are directly energized and the second lead frame 322 and the light emitting element 100 are connected to each other through the wire 330 in this embodiment. The light emitting device 100 may be connected to the lead frames 321 and 322 by a flip chip method or a die bonding method in addition to the wire bonding method.

The molding part 340 may surround and protect the light emitting device 100. In addition, the phosphor 350 may be included on the molding part 340 to change the wavelength of light emitted from the light emitting device 100.

The phosphor 350 may include a garnet-based phosphor, a silicate-based phosphor, a nitride-based phosphor, or an oxynitride-based phosphor.

For example, the garnet-base phosphor is _{YAG (Y 3 Al 5 O 12} : Ce 3 +) or TAG: may be a _{(Tb 3 Al 5 O 12 Ce} 3 +), wherein the silicate-based phosphor is (Sr, Ba, Mg, Ca) ₂ SiO ₄ : Eu ^{2 +} , and the nitride phosphor may be CaAlSiN ₃ : Eu ^{2 +} containing SiN, and the oxynitride phosphor may be Si _{6 - x Al x O x N 8 -x:} Eu 2 + (0 <x <6) can be.

The light of the first wavelength range emitted from the light emitting device 100 is excited by the fluorescent material 250 to be converted into the light of the second wavelength range and the light of the second wavelength range passes through the lens (not shown) The light path can be changed.

The light emitting device 100 may be a high output light emitting device in which two or more light emitting diodes are connected in series according to the embodiment described above and current spreading is improved because two adjacent light emitting diodes are electrically connected to each other by two or more bridge electrodes .

A plurality of light emitting device packages according to embodiments may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, and the like may be disposed on the light path of the light emitting device package. Such a light emitting device package, a substrate, and an optical member can function as a light unit. Still another embodiment may be implemented as a display device, an indicating device, a lighting system including the semiconductor light emitting device or the light emitting device package described in the above embodiments, for example, the lighting system may include a lamp, a streetlight .

Hereinafter, a headlamp and a backlight unit will be described as an embodiment of the lighting system in which the above-described light emitting device is disposed.

8 is a view illustrating an embodiment of a headlamp in which the light emitting device according to the embodiment is disposed.

8, light emitted from the light emitting module 710 in which the light emitting device package according to the embodiment is disposed is reflected by the reflector 720 and the shade 730, and then transmitted through the lens 740 and directed toward the front of the vehicle body .

The light emitting device package included in the light emitting module 710 may include a plurality of light emitting devices, but the present invention is not limited thereto.

FIG. 9 is a view illustrating a display device in which a light emitting device package according to an embodiment is disposed.

9, the display device 800 according to the embodiment includes a light source module 830 and 835, a reflection plate 820 on the bottom cover 810, a light source module 830 disposed in front of the reflection plate 820, A first prism sheet 850 and a second prism sheet 860 disposed in front of the light guide plate 840 and a second prism sheet 860 disposed between the first prism sheet 850 and the second prism sheet 860. The light guiding plate 840 guides light emitted from the light- A panel 870 disposed in front of the panel 870 and a color filter 880 disposed in the front of the panel 870.

The light source module includes the light emitting device package 835 described above on the circuit board 830. [ Here, the circuit board 830 may be a PCB or the like, and the light emitting device package 835 is the same as that described with reference to FIG.

The bottom cover 810 may house the components in the display device 800. The reflection plate 820 may be formed as a separate component as shown in the drawing, or may be formed to be coated on the rear surface of the light guide plate 840 or on the front surface of the bottom cover 810 with a highly reflective material Do.

Here, the reflection plate 820 can be made of a material having a high reflectance and can be used in an ultra-thin shape, and polyethylene terephthalate (PET) can be used.

The light guide plate 840 scatters light emitted from the light emitting device package module so that the light is uniformly distributed over the entire screen area of the LCD. Accordingly, the light guide plate 830 is made of a material having a good refractive index and transmittance. The light guide plate 830 may be formed of polymethyl methacrylate (PMMA), polycarbonate (PC), or polyethylene (PE). An air guide system is also available in which the light guide plate is omitted and light is transmitted in a space above the reflective sheet 820.

The first prism sheet 850 is formed on one side of the support film with a transparent and elastic polymeric material, and the polymer may have a prism layer in which a plurality of steric structures are repeatedly formed. As shown in the drawings, the plurality of patterns may be repeatedly provided with a stripe pattern.

In the second prism sheet 860, the edges and the valleys on one surface of the support film may be perpendicular to the edges and the valleys on one surface of the support film in the first prism sheet 850. This is to disperse the light transmitted from the light source module and the reflection sheet evenly in all directions of the panel 870.

In the present embodiment, the first prism sheet 850 and the second prism sheet 860 form an optical sheet, which may be formed of other combinations, for example, a microlens array or a diffusion sheet and a microlens array Or a combination of one prism sheet and a microlens array, or the like.

A liquid crystal display (LCD) panel may be disposed on the panel 870. In addition to the liquid crystal display panel 860, other types of display devices requiring a light source may be provided.

In the panel 870, the liquid crystal is positioned between the glass bodies, and the polarizing plate is placed on both glass bodies to utilize the polarization of light. Here, the liquid crystal has an intermediate property between a liquid and a solid, and liquid crystals, which are organic molecules having fluidity like a liquid, are regularly arranged like crystals. The liquid crystal has a structure in which the molecular arrangement is changed by an external electric field And displays an image.

A liquid crystal display panel used in a display device is an active matrix type, and a transistor is used as a switch for controlling a voltage supplied to each pixel.

A color filter 880 is provided on the front surface of the panel 870 so that light projected from the panel 870 transmits only red, green, and blue light for each pixel.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

100: light emitting elements 110a to 110d: light emitting diodes
120: substrate 130: buffer layer
140: light emitting structure 142: first conductivity type semiconductor layer
144: active layer 146: second conductivity type semiconductor layer
150a to 150d: first electrode 152: first main electrode
154: first branch electrodes 160a to 160d: second electrode
162: second main electrode 164: second branch electrode
170: ohmic layer 175: bridge electrode
180: insulating layer
310: package body 321, 322: first and second lead frames
330: wire 340: molding part
350: phosphor 710: light emitting module
720: Reflector 730: Shade
800: Display device 810: Bottom cover
820: reflector 840: light guide plate
850: first prism sheet 860: second prism sheet
870: Panel 880: Color filter

Claims (18)

In a light emitting device in which at least two light emitting diodes are connected in series,
The light emitting diode includes a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode on the first conductivity type semiconductor layer; and a second electrode on the second conductivity type semiconductor layer, Electrode,
The first electrode is electrically connected to the second electrode of the adjacent light emitting diode by at least two bridge electrodes,
Wherein the light emitting diode further comprises an insulating layer formed on side surfaces of the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer. The method according to claim 1,
Wherein the first electrode comprises a first main electrode and at least two first branch electrodes branched from the first main electrode. 3. The method of claim 2,
Wherein the second electrode comprises a second main electrode and at least two second branch electrodes branched from the second main electrode. The method of claim 3,
Wherein the bridge electrode electrically connects the first main electrode of the first electrode and the second main electrode of the second electrode of the adjacent light emitting diode. The method of claim 3,
Wherein at least one first branch electrode of the first electrode is located between two adjacent second branch electrodes of a second electrode of the same light emitting diode. The method of claim 3,
Wherein at least one second branch electrode of the second electrode is located between adjacent two first branch electrodes of the first electrode of the same light emitting diode. delete The method according to claim 1,
And an ohmic layer between the second conductive semiconductor layer and the second electrode. The method according to claim 1,
Wherein the light emitting structure is formed on a substrate, and a light extracting structure is formed on a surface of the substrate adjacent to the light emitting structure. The method according to claim 1,
And a second electrode pad is formed on the second electrode of the light emitting diode located at the first end of the at least two light emitting diodes. 11. The method of claim 10,
Wherein a first electrode pad is formed on a first electrode of a light emitting diode located at a second end opposite to the first end of the at least two light emitting diodes. In a light emitting device in which at least two light emitting diodes are connected in series,
The light emitting diode includes a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode on the first conductivity type semiconductor layer; and a second electrode on the second conductivity type semiconductor layer, Electrode,
The first electrode is electrically connected to the second electrode of the adjacent light emitting diode by at least two bridge electrodes,
Wherein the first electrode includes a first main electrode and at least two first branch electrodes branched from the first main electrode,
Wherein at least two first branch electrodes of the first electrode have a symmetrical structure with respect to each other. 13. The method of claim 12,
Wherein the second electrode includes a second main electrode and two or more second branch electrodes branched from the second main electrode,
Wherein at least two second branch electrodes of the second electrode have a symmetrical structure with respect to each other. The method according to claim 1,
Wherein the insulating layer electrically isolates between the adjacent two light emitting diodes and between the bridge electrode and the light emitting structure. In a light emitting device in which at least two light emitting diodes are connected in series,
The light emitting diode includes a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode on the first conductivity type semiconductor layer; and a second electrode on the second conductivity type semiconductor layer, Electrode,
The first electrode is electrically connected to the second electrode of the adjacent light emitting diode by at least two bridge electrodes,
Wherein the first electrode includes a first main electrode and at least two first branch electrodes branched from the first main electrode,
Wherein the second electrode includes a second main electrode and at least two second branch electrodes branched from the second main electrode,
Wherein at least a part of the first branch electrode of the first electrode and the second branch electrode of the second electrode are horizontally overlapped with each other. 16. The method of claim 15,
Wherein the first branch electrode of the first electrode and the second branch electrode of the second electrode are alternately arranged. 16. The method of claim 15,
Wherein the first main electrode of the first electrode and the second main electrode of the second electrode are disposed to face each other. The method according to claim 1,
The bridge electrode may be formed of a metal such as molybdenum (Mo), chromium (Cr), nickel (Ni), gold (Au), aluminum (Al), titanium (Ti), platinum (Pt), vanadium (V), tungsten (Pd), copper (Cu), rhodium (Rh) or iridium (Ir) or an alloy of the metals.

Images