KR20120068295A - A light emitting device - Google Patents

Abstract

PURPOSE: A light emitting device is provided to improve luminance and reliability by reducing lattice defect on an active layer. CONSTITUTION: A light emitting device includes a light emitting structure(120) and a first electrode on the light emitting structure. A first conductive semiconductor layer, a buffer layer, an active layer(124), and a second conductive semiconductor layer(126) are laminated on the light emitting structure. The band gap energy of the buffer layer has a value between the band gap energy of the first conductive semiconductor layer and the band gap energy of the active layer. The band gap energy of the buffer layer has 0.18eV or more than the band gap energy of the active layer.

Description

Light emitting device

The present invention relates to a light emitting device and a light emitting device package.

A light emitting diode (LED) is a kind of semiconductor device that transmits and receives a signal by converting electricity into infrared light or light using characteristics of a compound semiconductor.

Group III-V nitride semiconductors are spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their physical and chemical properties.

These light emitting diodes do not contain environmentally harmful substances such as mercury (Hg) used in existing lighting equipment such as incandescent lamps and fluorescent lamps, and thus have excellent eco-friendliness and have advantages such as long life and low power consumption. It is replacing them.

The embodiment provides a light emitting device capable of reducing lattice defects and improving brightness and reliability.

The light emitting device according to the embodiment includes a light emitting structure in which a first conductive semiconductor layer, a buffer layer, an active layer, and a second conductive semiconductor layer are stacked, and a first electrode on the light emitting structure, wherein the band gap energy of the buffer layer is It has a value between the band gap energy of the first conductive semiconductor layer and the band gap energy of the active layer, the band gap energy of the buffer layer is different from the band gap energy of the active layer by 0.18 eV or more. Each of the buffer layer and the active layer is a nitride semiconductor layer having In _x Ga _{1- x} N (0 ≦ _x ≦ ₁ ), and may have different indium contents. The band gap energy of the buffer layer may be 0.18 eV or more greater than the band gap energy of the active layer.

The buffer layer may include a superlattice layer having a superlattice structure in which the first InGaN layer and the second InGaN layer are repeatedly stacked for at least 6 cycles. The first InGaN layer and the second InGaN layer have different indium (In) contents, and each band gap energy may be 0.18 eV or more greater than the band gap energy of the active layer.

The light emitting structure may be mesa-etched to expose the first conductivity type semiconductor layer, and the light emitting device may further include a substrate under the light emitting structure and a second electrode on the exposed first conductivity type semiconductor layer.

The light emitting device may further include an ohmic layer under the light emitting structure, a reflective layer under the ohmic layer, a bonding layer under the reflective layer, and a support layer under the bonding layer.

Embodiments can reduce lattice defects and improve brightness and reliability.

1 is a cross-sectional view showing a light emitting device according to an embodiment.
2 is a cross-sectional view illustrating a light emitting device according to another embodiment.
FIG. 3 shows the photoluminescence of the buffer layer and the active layer shown in FIG. 1.
4 illustrates a light emitting device package according to an embodiment.
5 is an exploded perspective view of an embodiment of a lighting device including a light emitting device package according to the embodiment.
6 illustrates a display device including a light emitting device package according to an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the description of an embodiment, each layer, region, pattern or structure may be "under" or "under" the substrate, each layer, region, pad or pattern. In the case where it is described as being formed at, "up" and "under" include both "directly" or "indirectly" formed through another layer. do. In addition, the criteria for up / down or down / down each layer will be described with reference to the drawings.

In the drawings, dimensions are exaggerated, omitted, or schematically illustrated for convenience and clarity of illustration. In addition, the size of each component does not necessarily reflect the actual size. The same reference numerals denote the same elements throughout the description of the drawings. Hereinafter, a light emitting device, a method of manufacturing the same, and a light emitting device package according to embodiments will be described with reference to the accompanying drawings.

1 is a cross-sectional view illustrating a light emitting device 100 according to an embodiment. Referring to FIG. 1, the light emitting device 100 includes a substrate 110, a light emitting structure 120, a conductive layer 130, a first electrode 142, and a second electrode 144.

The substrate 110 may be any one of a sapphire substrate, a silicon (Si) substrate, a zinc oxide (ZnO) substrate, and a nitride semiconductor substrate, or a template substrate on which at least one of GaN, InGaN, AlGaN, and AlInGaN is stacked. have.

The light emitting structure 120 is disposed on the substrate 110 and includes a first conductive semiconductor layer 122, a buffer layer 123, an active layer 124, and a second conductive semiconductor layer 126. In addition, the light emitting structure 120 includes a second conductive semiconductor layer 126, an active layer 124, a buffer layer 123, and a first conductive semiconductor layer 122 to expose a portion of the first conductive semiconductor layer 122. A part of has an etched structure.

In order to alleviate the difference between the lattice constant and the coefficient of thermal expansion, a buffer layer (not shown) may be interposed between the substrate 110 and the light emitting structure 120, and the crystallinity of the first conductivity-type semiconductor layer 122 may be improved. An undoped semiconductor layer (not shown) may be interposed therebetween. In this case, the buffer layer may be grown at a low temperature, and the material may be a GaN layer or an AlN layer, but is not limited thereto. The undoped semiconductor layer may be lower than the first conductive semiconductor layer 122 because the n-type dopant is not doped. It may be the same as the first conductivity type semiconductor layer 122 except for having electrical conductivity.

The conductive layer 130 is disposed on the second conductive semiconductor layer 126 to increase the extraction efficiency of light emitted from the active layer 124 to the second conductive semiconductor layer 126. The conductive layer may be made of a transparent oxide material having high transmittance, such as indium tin oxide (ITO), tin oxide (TO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), or the like. have.

The first electrode 142 is disposed on the first conductive semiconductor layer 122 exposed by etching, and may be made of titanium (Ti) or the like. In addition, the second electrode 144 is disposed on the conductive layer 130 and may be made of nickel (Ni) or the like.

The first conductive semiconductor layer 122 may be an n-type semiconductor layer. For example, semiconductor material having a compositional formula of the first conductive type semiconductor layer 122 is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) For example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN may be selected, and n-type dopants such as Si, Ge, Sn, Se, Te, and the like may be doped.

The buffer layer 123 is disposed on the first conductivity type semiconductor layer 122. The active layer 124 is disposed on the buffer layer 123. The second conductive semiconductor layer 126 is disposed on the active layer 124 and may be a p-type semiconductor layer. For example, the second conductivity type semiconductor material having a composition formula of the semiconductor layer 126 is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) For example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc. may be selected, and p-type dopants such as Mg, Zn, Ca, Sr, and Ba may be doped.

The active layer 124 generates light by energy generated in the process of recombination of electrons provided from the n-type semiconductor layer 122 and holes provided from the p-type semiconductor layer 126. Can be. The active layer 124 may include a semiconductor material having a composition formula of In _x Al _y Ga _{1 -xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1), and the active layer 124 ) May be a multi quantum well structure (MQW) in which a quantum well layer and a quantum barrier layer are alternately stacked two or more times.

The buffer layer 123 is disposed between the first conductivity type semiconductor layer 122 and the active layer 124. The buffer layer 123 mitigates the difference in crystal lattice constant between the first conductivity type semiconductor layer 122 and the active layer 124, and has a lattice constant of the lattice constant of the first conductivity type semiconductor layer 122 and the active layer 124. Has the middle value of the lattice constant. For example, the lattice constant of the buffer layer 123 may be larger than the lattice constant of the first conductive semiconductor layer 122 and may be smaller than the lattice constant of the active layer 124.

The band gap energy of the buffer layer 123 has a value between the band gap energy of the first conductive semiconductor layer 122 and the band gap energy of the active layer 124, and the band gap energy of the buffer layer 123 is of the active layer 124. It differs from the band gap energy by more than 0.18 eV. For example, the band gap energy of the buffer layer 123 may be 0.18 eV or more greater than the band gap energy of the active layer 124.

The buffer layer 123 and the active layer 124 according to the embodiment may have a composition satisfying the band gap energy difference (0.18 eV) described above. For example, each of the buffer layer 123 and the active layer 124 may be a nitride semiconductor layer having In _x Ga _{1 - x} N (0 ≦ x ≦ 1, 0 ≦ _x ≦ 1), but may have different indium contents. For example, the indium content of the buffer layer 123 may be 0.09, and the indium content of the active layer 124 may be 0.15.

FIG. 3 illustrates photoluminescence PL of the buffer layer 123 and the active layer 124 illustrated in FIG. 1. Here, the y axis represents PL intensity, the lower x axis represents band gap energy, and the upper x axis represents wavelength. And g1 represents PL of the buffer layer 123 and the active layer 124 of the light emitting device according to the embodiment, and g2 represents PL of the general light emitting device.

Referring to FIG. 3, the band gap energy of the buffer layer SLSA of the light emitting device according to the embodiment is 3.04 eV and the band gap energy of the active layer WA is 2.86 eV. Therefore, the band gap energy difference between the buffer layer SLS1 and the active layer W1 according to the embodiment is 0.18 eV.

In contrast, the band gap energy of the buffer layer SLSB of the general light emitting device is 2.94 eV and the band gap energy of the active layer WB is 2.82 eV. Therefore, the band gap energy difference between the buffer layer SLS1 and the active layer W1 of the general light emitting device is 0.12 eV.

At this time, the half width BW1 of the buffer layer SLSA of the light emitting device according to the exemplary embodiment is smaller than the half width BW2 of the buffer layer SLSB of the general light emitting device. From this, it can be seen that the crystallinity of the buffer layer SLSB of the general light emitting device is lower than that of the buffer layer SLSA of the light emitting device according to the embodiment.

Accordingly, the light emitting device according to the embodiment improves the crystallinity of the buffer layer SLSA by increasing the band gap energy difference between the buffer layer SLSA and the active layer W1 by 0.18 eV or more, thereby reducing the lattice defects of the active layer W1. Can be reduced to improve brightness and reliability.

The buffer layer 123 illustrated in FIG. 1 has a superlattice layer having a superlattice structure in which first InGaN (not shown) and second InGaN (not shown) having different indium (In) contents are repeatedly stacked for at least 6 cycles ( Strained Layer Superlattice) may be included. In this case, the superlattice layer may provide a growth surface to help the growth of the high quality active layer as the first InGaN and the second InGaN are repeatedly stacked in at least 6 cycles or more. In this case, the band gap energy of each of the first InGaN and the second InGaN forming the superlattice layer is different from the band gap energy of the active layer 124 by 0.18 eV or more.

For example, the band gap energy of each of the first InGaN and the second InGaN of six or more cycles may be 0.18 eV or more greater than the band gap energy of the active layer 124.

2 is a cross-sectional view illustrating a light emitting device 200 according to another embodiment. 2, in the light emitting device 200, the light emitting device 100 may include a second electrode layer 205, a protective layer 230, a light emitting structure 240, a passivation layer 250, and a first electrode layer. (255).

The light emitting device 200 includes an LED using a plurality of compound semiconductor layers, for example, a compound semiconductor layer of Group 3-5 elements, and the LED may be a colored LED or a UV LED that emits light such as blue, green, or red. Can be. The emission light of the LED may be implemented using various semiconductors, but is not limited thereto.

The second electrode layer 205 includes a support layer 210, a bonding layer 215, a reflective layer 220, and an ohmic layer 225. The support layer 210 may be a conductive substrate or an insulating substrate, and supports the light emitting structure 240. For example, the support layer 210 may include copper (Cu), gold (Au), nickel (Ni), molybdenum (Mo), copper-tungsten (Cu-W), carrier wafers (eg, Si, Ge, GaAs). , ZnO, SiC, SiGe), and a conductive sheet.

The bonding layer 215 is a bonding layer, and is disposed under the reflective layer 220, the ohmic layer 225, and the protective layer 230, so that the layers 220, 225, and 230 are bonded to the support layer 210. Since the bonding layer 215 is formed to bond the support layer 210 to the bonding method, the bonding layer 215 is not necessarily formed when the support layer 210 is formed by plating or deposition. ) May optionally be formed. The bonding layer 215 may include a barrier metal or a bonding metal, and may include, for example, at least one of Ti, Au, Sn, Ni, Cr, Ga, In, Bi, Cu, Ag, or Ta.

The reflective layer 220 may reflect light incident from the light emitting structure 240, thereby improving light extraction efficiency. The reflective layer 220 may be formed of, for example, a metal or an alloy including at least one of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and Hf. In addition, the reflective layer 220 may be formed in multiple layers using the metal or alloy and a light-transmitting conductive material such as IZO, IZTO, IAZO, IGZO, IGTO, AZO, or ATO. For example, the reflective layer 220 may be laminated with IZO / Ni, AZO / Ag, IZO / Ag / Ni, AZO / Ag / Ni, or the like. The reflective layer 222 is to increase the light efficiency and does not have to be formed.

The ohmic layer 225 is in ohmic contact with the second conductive semiconductor layer 242 to smoothly supply power to the light emitting structure 240. For example, the ohmic layer 225 may include indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), and indium gallium (IGTO). tin oxide), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IrOx, RuOx, RuOx / ITO, Ni / IrOx / Au, and Ni / IrOx / Au / ITO, Ag, It may include at least one of Pt, Rh, Ni.

Although not shown in FIG. 3, a current blocking layer CBL may be disposed between the second electrode layer 205 and the second conductive semiconductor layer 242. The current blocking layer (not shown) may be disposed to overlap at least a portion of the first electrode layer 255, thereby alleviating a phenomenon in which current is concentrated under the first electrode layer 255, thereby emitting light of the light emitting device 200. The efficiency can be improved.

The protective layer 230 may be disposed on an uppermost branch region of the second electrode layer 205 to be adjacent to a side of the second electrode layer 205. For example, the protective layer 230 may be disposed on the bonding layer 215 adjacent to the light emitting structure 240. When the bonding layer 215 is not formed, the bonding layer 215 may be disposed in the peripheral region on the support layer 210.

The light emitting structure 240 is disposed on the second electrode layer 205 and the protective layer 230. The side surface of the light emitting structure 240 may be an inclined surface in an isolation etching process divided into unit chips, and the side surface of the inclined light emitting structure 240 may overlap at least a portion of the protective layer 230. A portion of the top surface of the protective layer 230 may be opened by isolation etching. For example, a portion of the protective layer 130 may overlap the light emitting structure 240, and a portion of the protective layer 130 may not overlap.

The protective layer 230 may reduce a phenomenon in which the interface between the light emitting structure 240 and the second electrode layer 205 is peeled off, thereby reducing the reliability of the light emitting device 200. For example, when the isolation layer 230 performs isolation etching to separate the light emitting structure 240 into unit chips, the fragments generated from the bonding layer 215 may be divided into the second conductive semiconductor layer 242 and the active layer 244. ) Or between the active layer 244 and the first conductive semiconductor layer 246 to prevent an electrical short.

The light emitting structure 240 may have a structure in which the second conductive semiconductor layer 242, the active layer 244, the buffer layer 245, and the first conductive semiconductor layer 246 are stacked.

The second conductive semiconductor layer 246 is disposed on the second electrode layer 205 and is a compound semiconductor of Group III-V group elements doped with the second conductive dopant, for example, GaN, AlN, AlGaN, InGaN, InN. , InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP and the like. The second conductivity type dopant includes a P type dopant such as Mg and Zn, and the second conductivity type semiconductor layer 242 may be formed as a single layer or a multilayer, but is not limited thereto.

The active layer 244 is disposed on the second conductivity type semiconductor layer 242 and may include any one of a single quantum well structure, a multi quantum well structure (MQW), a quantum dot structure, or a quantum line structure. The active layer 144 may be formed of a well layer and a barrier layer, for example, an InGaN well layer / GaN barrier layer or an InGaN well layer / AlGaN barrier layer, using a compound semiconductor material of Group III-V elements.

The buffer layer 245 is disposed on the active layer 244. The buffer layer 245 mitigates the difference in crystal lattice constant between the active layer 244 and the first conductivity-type semiconductor layer 246, and the lattice constant of the buffer layer 245 is the lattice constant of the first conductivity-type semiconductor layer 246 and the active layer 244. Has the middle value of the lattice constant. For example, the lattice constant of the buffer layer 245 may be greater than the lattice constant of the first conductivity type semiconductor layer 246 and less than the lattice constant of the active layer 244.

The band gap energy of the buffer layer 245 differs by at least 0.18 eV based on the band gap energy of the active layer 124. In addition, the buffer layer 245 may include a superlattice layer as described above.

As described above with reference to FIG. 3, the light emitting device according to the embodiment improves the crystallinity of the buffer layer 245 by increasing the band gap energy difference between the buffer layer 245 and the active layer 244 by 0.18 eV or more, thereby increasing the crystallinity of the active layer. The lattice defect of 244 can be reduced to improve brightness and reliability.

The first conductive semiconductor layer 246 may be a compound semiconductor of a group III-V element doped with a first conductive dopant, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP and the like can be selected. The first conductivity type dopant includes an N type dopant such as Si, Ge, Sn, Se, Te, or the like. The first conductivity type semiconductor layer 142 may be formed as a single layer or a multilayer, but is not limited thereto.

The passivation layer 250 may have an upper surface of the first conductivity type semiconductor layer 246 open and may be formed on a side surface of the light emitting structure 240. The passivation layer 250 may be formed to cover side surfaces of the second conductive semiconductor layer 242, the active layer 244, and the first conductive semiconductor layer 246 of the light emitting structure 240. In addition, the passivation layer 250 may be disposed on a portion of the upper surface of the first conductivity-type semiconductor layer 246 adjacent to the side surface of the light emitting structure 240, but is not limited thereto. The passivation layer 250 may be formed to electrically protect the light emitting structure 240, and for example, SiO ₂ , SiO _x , SiO _x N _y , Si ₃ N ₄ , to be formed of Al ₂ O ₃ But it is not limited thereto.

The first electrode layer 255 is disposed on the upper surface of the light emitting structure 240. For example, the first electrode layer 255 may be disposed on an upper surface of the first conductivity type semiconductor layer 246, and may be branched to have a predetermined pattern shape, but is not limited thereto.

In the first conductive semiconductor layer 246, a roughness pattern 260 may be formed to increase light extraction efficiency. In addition, a roughness pattern may be formed on the upper surface of the first electrode layer 255, but is not limited thereto.

4 illustrates a light emitting device package according to an embodiment. Referring to FIG. 4, the light emitting device package is installed on the package body 320, the first electrode layer 311 and the second electrode layer 312 installed on the package body 320, and the package body 320. The light emitting device 300 according to the embodiment is electrically connected to the first electrode layer 311 and the second electrode layer 312, and a filler 340 surrounding the light emitting device 300.

The package body 320 may include a silicon material, a synthetic resin material, or a metal material. An inclined surface may be formed around the light emitting device 300 to increase light extraction efficiency.

The first electrode layer 311 and the second electrode layer 312 are electrically separated from each other, and provide power to the light emitting device 300. In addition, the first electrode layer 311 and the second electrode layer 312 can increase the light efficiency by reflecting the light generated from the light emitting device 300, and discharges heat generated from the light emitting device 300 to the outside It can also play a role.

The light emitting device 300 may be installed on the package body 320 or on the first electrode layer 311 or the second electrode layer 312. Although the light emitting device 300 is shown to be electrically connected to the first electrode layer 311 and the second electrode layer 312 by a wire method, it is not limited thereto. That is, the light emitting device 300 may be electrically connected to the first electrode layer 311 and the second electrode layer 312 by any one of a wire method, a flip chip method, or a die bonding method.

The filler 340 may surround and protect the light emitting device 300. The filler 340 may be made of a colorless transparent polymer resin material such as epoxy or silicon. In addition, the filler 340 may include a phosphor to change the wavelength of light emitted from the light emitting device 300. The light emitting device package may include at least one or a plurality of light emitting devices of the above-described embodiments, but is not limited thereto.

Another embodiment may be implemented as a display device, an indicator device, or a lighting system including the light emitting device or the light emitting device package described in the above embodiments, for example, the display device is a backlight unit, the lighting system is a lamp, It may include a street lamp.

5 is an exploded perspective view of an embodiment of a lighting device including a light emitting device package according to the embodiment. Referring to FIG. 5, the lighting apparatus according to the embodiment includes a light source 750 for projecting light, a housing 700 in which the light source 750 is embedded, a heat dissipation unit 740 for dissipating heat from the light source 750, and And a holder 760 which couples the light source 750 and the heat dissipation part 740 to the housing 700.

The housing 700 includes a socket coupling portion 710 coupled to an electrical socket (not shown), and a body portion 730 connected to the socket coupling portion 710 and having a light source 750 embedded therein. One air flow hole 720 may be formed through the body portion 730.

A plurality of air flow port 720 is provided on the body portion 730 of the housing 700, the air flow port 720 is composed of one air flow port, or a plurality of flow ports other than the radial arrangement as shown Various arrangements are also possible.

The light source 750 includes a plurality of light emitting device packages 752 on the substrate 754. Here, the substrate 754 may be a shape that can be inserted into the opening of the housing 700, and may be made of a material having a high thermal conductivity to transfer heat to the heat dissipation unit 740, as described below.

In addition, a holder 760 is provided below the light source 750, and the holder 760 may include a frame and another air flow port. In addition, although not shown, an optical member may be provided under the light source 750 to diffuse, scatter, or converge the light projected from the light emitting device package 752 of the light source 750. The lighting apparatus according to the embodiment may include the light emitting device package according to the above-described embodiment, thereby improving brightness and reliability.

6 illustrates a display device including a light emitting device package according to an embodiment.

Referring to FIG. 6, the display device 800 is disposed in front of the light source modules 830 and 835, the reflector 820 on the bottom cover 810, and the reflector 820 and is emitted from the light source modules 830 and 835. An optical sheet including a light guide plate 840 for guiding the light to the front of the display device, a prism sheets 850 and 860 disposed in front of the light guide plate 840, and an optical sheet disposed in front of the prism sheets 850 and 860. The panel 870 may include a color filter 880 disposed in front of the panel 870. The bottom cover 810, the reflector 820, the light source modules 830 and 835, the light guide plate 840, and the optical sheet may form a backlight unit.

The light source module includes a light emitting device package 835 on the substrate 830. Here, the PCB 830 may be used, and the light emitting device package 835 may be the embodiment shown in FIG. 4.

The bottom cover 810 may receive components in the display device 800. In addition, the reflective plate 820 may be provided as a separate component as shown in the drawing, or may be provided in the form of a high reflective material on the rear surface of the light guide plate 840 or the front surface of the bottom cover 810. .

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 830 scatters the light emitted from the light source module so that the light is uniformly distributed over the entire area of the screen of the liquid crystal display. Accordingly, the light guide plate 830 is made of a material having good refractive index and high transmittance, and may be formed of polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), or the like.

The first prism sheet 850 may be formed of a translucent and elastic polymer material on one surface of the support film, and the polymer may have a prism layer in which a plurality of three-dimensional structures are repeatedly formed. Here, the plurality of patterns may be provided in the stripe type and the valley repeatedly as shown.

In addition, the direction of the floor and the valley of one surface of the support film in the second prism sheet 860 may be perpendicular to the direction of the floor and the valley of one surface of the support film in the first prism sheet 850. This is to evenly distribute the light transmitted from the light source module and the reflective sheet to the front of the panel 870.

Although not shown, a protective sheet may be provided on each prism sheet, and a protective layer including light diffusing particles and a binder may be provided on both surfaces of the support film. In addition, the prism layer may be made of a polymer material selected from the group consisting of polyurethane, styrenebutadiene copolymer, polyacrylate, polymethacrylate, polymethylmethacrylate, polyethylene terephthalate elastomer, polyisoprene, and polysilicon. have.

Although not shown, a diffusion sheet may be disposed between the light guide plate 840 and the first prism sheet 850. The diffusion sheet may be made of a polyester and polycarbonate-based material, and may maximize the light projection angle through refraction and scattering of light incident from the backlight unit. The diffusion sheet includes a support layer including a light diffusing agent, a first layer and a second layer formed on the light exit surface (the first prism sheet direction) and the light incident surface (the reflection sheet direction) and do not include the light diffusing agent. It may include.

In the present embodiment, the diffusion sheet, the first prism sheet 850 and the second prism sheet 860 form an optical sheet, and the optical sheet is made of another combination, for example, a micro lens array or a diffusion sheet and a micro lens array. Or a combination of one prism sheet and a micro lens array.

The liquid crystal display panel (Liquid Crystal Display) may be disposed in the panel 870, and in addition to the liquid crystal display panel 860, another type of display device requiring a light source may be provided. The panel 870 is in a state where the liquid crystal is located between the glass bodies and the polarizing plates are placed on both glass bodies in order to use 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.

The liquid crystal display panel used for the display device uses an active matrix method as a switch for adjusting a voltage supplied to each pixel. In addition, the front surface of the panel 870 is provided with a color filter 880 to transmit the light projected by the panel 870, only the red, green and blue light for each pixel can represent an image. The display device according to the exemplary embodiment may improve brightness and reliability by using the light source module including the light emitting device package according to the exemplary embodiment.

Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

110: substrate, 120: light emitting structure
122: first conductive semiconductor layer 123: buffer layer
124: active layer 126: second conductive semiconductor layer
130: conductive layer 142: first electrode
144: second electrode 205: second electrode layer
210: support layer 215: bonding layer
220: reflective layer 225: ohmic layer
230: protective layer 250: passivation layer
255: first electrode layer

Claims (7)

A light emitting structure in which a first conductive semiconductor layer, a buffer layer, an active layer, and a second conductive semiconductor layer are stacked; And
A first electrode on the light emitting structure,
The band gap energy of the buffer layer has a value between the band gap energy of the first conductive semiconductor layer and the band gap energy of the active layer, and the band gap energy of the buffer layer is different from the band gap energy of the active layer by 0.18 eV or more. I'm a luminous device. The method of claim 1, wherein each of the buffer layer and the active layer,
A light emitting device comprising a nitride semiconductor layer having In _x Ga _{1 - x} N (0≤x≤1) and having different indium contents. The method of claim 1,
The band gap energy of the buffer layer is 0.18 eV or more greater than the band gap energy of the active layer. The method of claim 1, wherein the buffer layer,
A light emitting device comprising a superlattice layer having a superlattice structure in which a first InGaN layer and a second InGaN layer are repeatedly stacked for at least six cycles. The method of claim 4, wherein
The light emitting device of the first InGaN layer and the second InGaN layer is different in content of indium (In), each band gap energy is at least 0.18 eV greater than the band gap energy of the active layer. The method of claim 1,
The light emitting structure is mesa etched to expose the first conductivity type semiconductor layer,
A substrate under the light emitting structure; And
The light emitting device further comprises a second electrode on the exposed first conductive semiconductor layer. The method of claim 1,
An ohmic layer under the light emitting structure;
A reflective layer under the ohmic layer;
A bonding layer below the reflective layer; And
The light emitting device further comprises a support layer below the bonding layer.

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