KR20130096336A - Light emitting device - Google Patents

Abstract

PURPOSE: A light emitting device is provided to improve light emitting efficiency by relieving the stress between a first conductive semiconductor layer and an active layer. CONSTITUTION: A light emitting structure includes a first conductive semiconductor layer (210), an active layer (230), and a second conductive semiconductor layer (240). An electron injection layer (220) is located between the first conductive semiconductor layer and the active layer and includes In. The active layer includes a well layer and a barrier layer which are alternately located. The electron injection layer includes multiple sub layers. An energy band gap of the sub layer is wider than an energy band gap of the well layer. The multiple sub layers include a sub well layer and a sub barrier layer which are alternately located.

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.

Such light emitting diodes, when electrons are injected in the n-GaN layer, electrons stably lose energy and must be bound to the active layer to contribute to light emission. ) And cause a leakage current, thereby reducing the luminous efficiency of the light emitting diode.

1 is a diagram showing an energy band diagram of a light emitting diode according to the prior art for solving this problem.

Referring to FIG. 1, an electron injection layer 10 is positioned between an n-GaN layer and an active layer MQW.

The electron injection layer 10 is an InGaN layer composed of a single layer with an energy band offset (? E ₀ ) greater than or equal to 88 nV from the n-GaN layer, and when electrons are supplied from the n-GaN layer to the electron injection layer 10. By scattering the energy of the electron to the phonon of the electron injection layer 10 by scattering, the electron stably loses energy, and stably lost energy is bound to the active layer (MQW) to leak It serves to reduce current.

However, in the light emitting diode according to the prior art including the electron injection layer 10 composed of a single layer, when the n-GaN layer and the active layer (MQW) growth, a stress due to the difference in lattice constant occurs, There is still a problem that a crack occurs on the surface of the light emitting structure, thereby lowering the luminous efficiency of the light emitting diode.

The embodiment is intended to improve the luminous efficiency of the light emitting device by growing a high quality active layer.

A light emitting device according to an embodiment includes a light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; And an electron injection layer disposed between the first conductivity type semiconductor layer and the active layer and including In, wherein the active layer is alternately positioned with at least one well layer and a barrier layer, and the electron injection layer includes a plurality of sub layers. And the energy bandgap of the sublayer is wider than the energy bandgap of the well layer.

The plurality of sub layers may include a sub well layer and a sub barrier layer that are alternately positioned at least once.

The sub well layer and the sub barrier layer may have compositions of In _X Ga _{1 - X} N and In _Y Ga _{1 - Y} N (0 <Y <X <1), respectively.

The well layer of the active layer may include In, and the In content of the sub layer may be less than the In content of the well layer.

Each of the plurality of sublayers may have a thickness of about 1 nm to about 7 nm.

The first conductive semiconductor layer and the sub well layer may have an energy band offset of 0.15 to 0.25 eV.

The first conductive semiconductor layer and the sub barrier layer may have an energy band offset of 0.088 to 0.15 eV.

The display device may further include a first electrode on the first conductive semiconductor layer and a second electrode on the second conductive semiconductor layer.

The second electrode may be a conductive support substrate.

The light emitting structure may be positioned on a substrate, and a light extraction pattern may be positioned on a surface of the substrate adjacent to the light emitting structure.

At least one of an ohmic contact region and a reflective layer may be positioned between the second conductive semiconductor layer and the conductive support substrate.

The passivation layer may be positioned on the side of the light emitting structure.

An electron blocking layer may be further included between the active layer and the second conductive semiconductor layer.

The plurality of server layers may have the same thickness, different thicknesses, or at least two layers having the same thickness.

The roughness pattern may be located on an upper surface of the light emitting structure.

According to the embodiment, electrons are stably injected into the active layer, and stress between the first conductive semiconductor layer and the active layer is alleviated, thereby improving luminous efficiency of the light emitting device.

1 is a view showing an energy band diagram of a light emitting diode according to the prior art for solving this problem,
2 and 3 are cross-sectional views of the light emitting device according to the embodiment;
4 is a diagram illustrating an energy band diagram of a light emitting device according to an embodiment;
5 is a graph showing a comparison of the leakage current to the total injection current of the light emitting device according to the prior art and the light emitting device according to the embodiment,
6 is a graph illustrating internal quantum efficiency of the light emitting device according to the prior art and the light emitting device according to the embodiment.
7 is a view showing an embodiment of a light emitting device package in which the light emitting device according to the embodiment is disposed;
8 is a view illustrating an embodiment of a head lamp in which a light emitting device package is disposed according to an embodiment;
9 is a diagram illustrating an exemplary embodiment of a display device in which a light emitting device package 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. In addition, the size of each component does not necessarily reflect the actual size.

2 and 3 are cross-sectional views of light emitting devices according to the embodiment, FIG. 2 shows a horizontal light emitting device, and FIG. 3 shows a vertical light emitting device.

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

The light emitting device according to the embodiment includes a light emitting structure 250 including a first conductive semiconductor layer 210, an active layer 230, and a second conductive semiconductor layer 240, and the first conductive semiconductor layer 210. ) And the electron injection layer 220 including In and positioned between the active layer 230 and In.

The light emitting structure 250 may include, for example, a metal organic chemical vapor deposition (MOCVD), a chemical vapor deposition (CVD), a plasma chemical vapor deposition (PECVD), Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), and the like may be formed using, but are not limited thereto.

A roughness pattern is formed on the surface of the light emitting structure 250 to diffusely reflect light generated in the active layer 230, thereby improving light extraction efficiency of the light emitting device.

The first conductivity-type semiconductor layer 210 may be formed of a semiconductor compound, and for example, may be formed of a compound semiconductor such as Group 3-5 or Group 2-6. In addition, the first conductivity type dopant may be doped. When the first conductivity type semiconductor layer 210 is an n type semiconductor layer, the first conductivity type dopant may include Si, Ge, Sn, Se, or Te as an n type dopant, but is not limited thereto. In addition, when the first conductivity type semiconductor layer 210 is a p type semiconductor layer, the first conductivity type dopant may include Mg, Zn, Ca, Sr, or Ba as a p type dopant.

The first conductive semiconductor layer 210 may include 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). It may include. The first conductive semiconductor layer 210 may be formed of any one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP.

The active layer 230 is a layer in which electrons and holes meet each other to emit light having energy determined by an energy band inherent to an active layer (light emitting layer) material. For example, the first conductivity type semiconductor layer 210 When the n-type semiconductor layer and the second conductivity-type semiconductor layer 240 is a p-type semiconductor layer, electrons are supplied from the first conductivity-type semiconductor layer 210 and holes are formed in the second conductivity-type semiconductor layer 240. Can be provided.

The active layer 230 may be formed of at least one of a single well structure, a multiple well structure, a quantum-wire structure, and a quantum dot structure. For example, the active layer 230 may be injected with trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) to form a multi-quantum well structure. It is not limited to this.

When the active layer 230 has a multi-quantum well structure, a well layer and a barrier layer are alternately stacked once, and the well layer / barrier layer is InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs. It may be formed of one or more pair structures of (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP, but is not limited thereto. The well layer may be formed of a material having an energy band gap narrower than that of the barrier layer.

A conductive cladding layer (not shown) may be formed on or under the active layer 230. 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. In addition, the conductive clad layer may be doped with n-type or p-type.

The second conductive semiconductor layer 240 may be formed of a semiconductor compound. For example, the second conductive semiconductor layer 240 may be formed of a group III-V compound semiconductor doped with a second conductive dopant. A second conductive semiconductor layer 240 is, for example, having a compositional formula of _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) It may include a semiconductor material. When the second conductive semiconductor layer 240 is a p-type semiconductor layer, the second conductive dopant may be a p-type dopant and may include Mg, Zn, Ca, Sr, or Ba. In addition, when the second conductivity type semiconductor layer 240 is an n type semiconductor layer, the second conductivity type dopant may include Si, Ge, Sn, Se, or Te as an n type dopant, but is not limited thereto.

In the present exemplary embodiment, the first conductive semiconductor layer 210 may be an n-type semiconductor layer, and the second conductive semiconductor layer 240 may be a p-type semiconductor layer. Alternatively, the first conductive semiconductor layer 210 may be a p-type semiconductor layer, and the second conductive semiconductor layer may be an n-type semiconductor layer.

In addition, an n-type semiconductor layer (not shown) is formed on the second conductive semiconductor layer 240 when a semiconductor having a polarity opposite to that of the second conductive type, for example, the second conductive semiconductor layer is a p-type semiconductor layer. can do. Accordingly, the light emitting structure may be implemented as 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.

An electron blocking layer 235 may be located between the active layer 230 and the second conductive semiconductor layer 240.

The electron blocking layer 235 is a potential barrier that prevents electrons provided from the first conductive semiconductor layer 210 from passing through the active layer 230 to the second conductive semiconductor layer 240 and causing leakage current. It serves as, for example, may be formed including AlGaN.

Referring to FIG. 2, the light emitting structure 250 may be positioned on the substrate 110.

The substrate 110 may be formed of a material suitable for growing a semiconductor material or a carrier wafer. In addition, it may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. The substrate 110 may use, for example, at least one of sapphire (Al ₂ O ₃ ), SiC, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga ₂ 0 ₃ . The substrate 110 may be wet-cleaned to remove impurities on the surface.

The buffer layer 115 may be grown between the substrate 110 and the light emitting structure 250 to alleviate the difference in lattice mismatch and thermal expansion coefficient of the material. The material of the buffer layer 115 may be formed of at least one of Group III-V compound semiconductors, for example, GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. An undoped semiconductor layer may be formed on the buffer layer 115, but is not limited thereto.

The light extraction pattern 110a may be formed on a surface of the substrate 110 adjacent to the light emitting structure 250.

The light extraction pattern 110a may be, for example, photo-lithography, e-beam lithography, laser hologram lithography, nano-imprinted lithography, or It may be formed by dry etching, but is not limited thereto.

When the light emitting structure 250 is grown on the substrate 110 on which the light extraction pattern 110a is formed, the light generated by the active layer 230 is diffusely reflected in the light extraction pattern 110a, and thus, inside the light emitting device. The light extraction efficiency of the light emitting device may be improved by changing the path of the light to increase the escape probability of the light.

The light extraction pattern 110a may be formed to protrude in the direction of the light emitting structure 250 as shown in FIG. 2A, or may be formed to be recessed in the opposite direction of the light emitting structure 250 as shown in FIG. 2B. In some embodiments, the present invention may be formed in various shapes and is not limited thereto.

A portion of the second conductive semiconductor layer 240, the active layer 230, and the first conductive semiconductor layer 210 may be mesa-etched to form a first electrode 130 on an opening surface of the first conductive semiconductor layer 210. ) Is disposed, and a second electrode 140 is formed on the second conductive semiconductor layer 240.

The first electrode 130 and the second electrode 140 each include at least one of aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), or gold (Au). It can be formed into a single layer or a multi-layer structure.

Referring to FIG. 3, the light emitting structure 250 may be positioned on the conductive support substrate 150.

The conductive support substrate 150 supports the light emitting structure 250 and may be formed of a material having high electrical conductivity and thermal conductivity. For example, the conductive support substrate 150 may be formed of molybdenum (Mo), silicon (Si), tungsten (W), copper (Cu), or aluminum (Al) as a base substrate having a predetermined thickness. It may be made of a material selected from the group or alloys thereof, and also, gold (Au), copper alloy (Cu Alloy), nickel (Ni), copper-tungsten (Cu-W), carrier wafers (eg GaN, Si, Ge, GaAs, ZnO, SiGe, SiC, SiGe, Ga ₂ O _3, etc.) or a conductive sheet may be optionally included.

In the vertical light emitting device as illustrated in FIG. 3, the conductive support substrate 150 may serve as a second electrode.

An ohmic contact region 160 may be positioned between the light emitting structure 250 and the conductive support substrate 150 in contact with the second conductive semiconductor layer 240.

When the second conductivity-type semiconductor layer 240 is a p-type semiconductor layer, the second conductivity-type semiconductor layer 240 has a low impurity doping concentration, thus high contact resistance, and thus ohmic characteristics with a metal may not be good. The ohmic contact area 160 is for improving this and does not have to be formed.

The ohmic contact region 160 may be a light transmissive conductive layer and a metal may be selectively used. For example, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), and indium aluminum zinc oxide), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IZON (IZO Nitride), AGZO (Al Ga ZnO), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au, or Ni / IrOx / Au / ITO, Ag, Ni, Cr, Ti, Al, At least one of Rh, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt, Au, and Hf may be formed, but is not limited thereto.

The reflective layer 170 may be located under the ohmic contact region 160. The reflective layer 170 is formed of, for example, a material consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, or a selective combination thereof. It may be formed in multiple layers using a light transmissive conductive material such as IZO, IZTO, IAZO, IGZO, IGTO, AZO or ATO. In addition, the reflective layer 170 may be laminated with IZO / Ni, AZO / Ag, IZO / Ag / Ni, AZO / Ag / Ni, or the like. In addition, when the reflective layer 170 is formed of a material in ohmic contact with the light emitting structure (eg, the second conductivity-type semiconductor layer 240), the ohmic contact region 160 may not be formed separately, but is not limited thereto. Do not.

The reflective layer 170 may effectively reflect light generated by the active layer 230 to greatly improve light extraction efficiency of the light emitting device.

A bonding layer 175 may be formed between the reflective layer 170 and the conductive support substrate 150. The bonding layer 175 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. It does not limit to this.

In addition, a roughness pattern may be formed on a surface of the first conductivity-type semiconductor layer 210. The roughness pattern of the first conductive semiconductor layer 210 may be formed by performing a photo enhanced chemical (PEC) etching method or an etching process using a mask pattern. The roughness pattern is to increase the external extraction efficiency of the light generated by the active layer 230, and may have a regular period or an irregular period.

In addition, the passivation layer 180 may be formed on at least part of the side surface of the light emitting structure 250 and the first conductivity-type semiconductor layer 210.

The passivation layer 180 may be made of an insulating material, and the insulating material is made of non-conductive oxide or nitride to protect the light emitting structure. As an example, the passivation layer 180 may be formed of a silicon oxide (SiO ₂ ) layer, an oxynitride layer, and an aluminum oxide layer.

4 is a diagram illustrating an energy band diagram of a light emitting device according to an embodiment.

2 to 4, the electron injection layer 220 included in the light emitting device according to the embodiment will be described in detail.

The electron injection layer 220 according to the embodiment is positioned between the first conductivity type semiconductor layer 210 and the active layer 230, and may include In.

The electron injection layer 220 includes a plurality of sub layers, and as an example, FIG. 4 shows four sub layers 221 ˜ 224, but the present invention is not limited thereto.

The plurality of sub layers 221 to 224 may be formed by alternately stacking the sub well layers 221 and 223 and the sub barrier layers 222 and 224 at least once.

When the active layer 230 has a quantum well structure in which the well layer 231 and the barrier layer 232 are alternately stacked at least once, the sub well layers 221 and 223 or the sub barrier layers 222 and 224 may be formed. The energy band gap may be wider than the energy band gap of the well layer 231.

In other words, the higher the In content injected during the growth of the epitaxial semiconductor layer, the narrower the energy band gap. Thus, the In content is controlled when the well layer 231 and the sub layers 221 to 224 of the active layer 230 are grown. The In content of the sub layers 221 to 224 may be set to be smaller than the In content of the well layer 231.

The sub well layers 221 and 223 and the sub barrier layers 222 and 224 of the electron injection layer 220 are respectively In _X Ga _{1 - X} N and In _Y Ga _{1 - Y} N (0 <Y <X <1). ) May have a composition. In this case, since the energy band gaps of the sub well layers 221 and 223 are narrower than those of the sub barrier layers 222 and 224, the In content X of the sub well layers 221 and 223 is equal to the sub barrier layer 222. 224) is greater than the In content Y.

For example, when the light emitting device is a blue light emitting diode emitting blue light, the sub well layers 221 and 223 and the sub barrier layers 222 and 224 of the electron injection layer 220 are respectively In _X Ga _{1 −. X} N, In _Y Ga _{1 - Y} N (0.23>X>Y> 0.05).

The electron injection layer 220 is positioned between the first conductivity type semiconductor layer 210 and the active layer 230, and the sub well layers 221 and 223 and the sub barrier layers 222 and 224 are alternately stacked at least once. By forming the plurality of sub-layers 221 to 224, the stress between the first conductive semiconductor layer 210 and the active layer 230 when the active layer 230 is grown on the first conductive semiconductor layer 210. (Strain) can be improved to improve the crystal quality of the active layer 230, thereby improving the phenomenon that a crack occurs on the surface of the light emitting structure (250).

An energy band offset? E ₁ between the first conductive semiconductor layer 210 and the sub well layer 221 and an energy band between the first conductive semiconductor layer 210 and the sub barrier layer 222. The offset? E ₂ may be about 0.088 eV or more.

0.088 eV is the energy of the phonon of the InGaN material constituting the electron injection layer 220, and an energy band offset (? E ₁ ) between the first conductivity-type semiconductor layer 210 and the sub-well layer 221. And, the energy band offset? E ₂ between the first conductive semiconductor layer 210 and the sub-barrier layer 222 should be 0.088 eV or more, so that the electrons injected from the first conductive semiconductor layer 210 By providing energy to the phonon of the electron injection layer 220 by scattering, electrons can stably lose energy and are constrained in the active layer 230 to contribute to light emission.

As an example, an energy band offset? E ₁ between the first conductivity type semiconductor layer 210 and the sub well layer 221 is 0.15 to 0.25 eV, and the first conductivity type semiconductor layer 210 and the sub The energy band offset? E ₂ between the barrier layers 222 may be 0.088 to 0.15eV, and? E ₁ is greater than? E ₂ .

If the energy band offset? E ₁ between the first conductivity type semiconductor layer 210 and the sub well layer 221 is too large, electrons may not be smoothly injected into the active layer 230 and may be bound to the electron injection layer 220. If too small, the insertion effect of the electron injection layer 220 may be insignificant.

The electron injection layer 220 may include a plurality of sublayers 221 ˜ 224, and the number of sublayers is not limited. However, when the electron injection layer 220 includes too many sublayers, the mobility of electrons is lowered, so that light emission occurs. The luminous efficiency of the device may be lowered.

The thicknesses d ₁ to d ₄ of the plurality of sub layers 221 to 224 included in the electron injection layer 220 may be 1 to 7 nm, respectively.

When the thicknesses d ₁ to d ₄ of each of the sub layers 221 to 224 are smaller than 1 nm, the electron injection layer 220 may not properly function as electrons stably lose energy and are injected into the active layer 230. When the thicknesses d ₁ to d ₄ of each of the sub layers 221 to 224 are larger than 7 nm, stress is generated during the growth of the active layer 230 so that the quality of the epitaxial layer constituting the active layer 230 is rather high. Can be degraded.

The plurality of sublayers 221 ˜ 224 may have the same thicknesses d ₁ to d ₄ , may be different from each other, or the thicknesses of at least two sub layers may be the same, without being limited thereto.

5 is a graph illustrating a comparison of the leakage current to the total injection current of the light emitting device according to the prior art and the light emitting device according to the embodiment, Figure 6 is a light emitting device according to the prior art and the light emitting device according to the embodiment It is a graph comparing the quantum efficiency.

Graph (a) shows a case of a light emitting device that does not have an electron injection layer, graph (b) shows a case of a light emitting device comprising an electron injection layer having a single layer and having a thickness of 13nm, graph (c) shows a case of a light emitting device comprising four sub-layers according to the embodiment, each sub-layer including an electron injection layer having a thickness of 4nm.

Referring to FIG. 5, as compared with the conventional case, according to the embodiment, electrons provided from the first conductivity-type semiconductor layer 210 stably read energy and are bound to the active layer 230 to contribute to light emission. It can be seen that the ratio of leakage current to total injection current is significantly reduced.

In addition, referring to Figure 6, compared with the conventional case, it can be seen that the ratio of the leakage current is significantly reduced according to the embodiment to improve the internal quantum efficiency of the light emitting device.

7 is a diagram illustrating an embodiment of a light emitting device package in which a light emitting device is disposed, according to an exemplary embodiment.

The light emitting device package 300 according to the embodiment includes a body 310 having a cavity, a first lead frame 321 and a second lead frame 322 installed in the body 310, and the body 310. The light emitting device 100 according to the above-described embodiments is installed and 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 be formed including 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, although not shown, 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. Can be.

The first lead frame 321 and the second lead frame 322 are electrically separated from each other, and supplies a current to the light emitting device 100. In addition, the first lead frame 321 and the second lead frame 322 may increase the light efficiency by reflecting the light generated by the light emitting device 100, heat generated by the light emitting device 100 Can be discharged to the outside.

The light emitting device 100 may be installed on the body 310 or may be installed on the first lead frame 321 or the second lead frame 322. In the present embodiment, the first lead frame 321 and the light emitting device 100 are directly energized, and the second lead frame 322 and the light emitting device 100 are connected through a wire 330. 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, a phosphor 350 is 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.

Light in the first wavelength region emitted from the light emitting device 100 is excited by the phosphor 250 and converted into light in the second wavelength region, and the light in the second wavelength region passes through a lens (not shown). The light path can be changed.

A plurality of light emitting device packages according to the embodiment may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, and the like, which are optical members, may be disposed on an optical 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. Another embodiment may be implemented as a display device, an indicator device, or a lighting system including the semiconductor light emitting device or the light emitting device package described in the above embodiments, and for example, the lighting system may include a lamp or a street lamp. .

Hereinafter, a head lamp and a backlight unit will be described as an embodiment of a lighting system in which a light emitting device package according to the above embodiments is disposed.

8 is a diagram illustrating an embodiment of a head lamp in which a light emitting device package is disposed according to an embodiment.

Referring to FIG. 8, after the light emitted from the light emitting module 710 in which the light emitting device package is disposed is reflected by the reflector 720 and the shade 730, the light is transmitted through the lens 740 to face the front of the vehicle body. Can be.

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

In the light emitting device package including the light emitting device according to the embodiment, the electron injection layer 220 having a plurality of sub layers is disposed between the first conductive semiconductor layer 210 and the active layer 230 to reduce the stress of the active layer 230. By mitigating, the luminous efficiency of the light emitting module 710 can be improved as a whole.

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

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

The light source module includes the above-described light emitting device package 835 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. Here, the plurality of patterns may be provided in the stripe type and the valley repeatedly as shown.

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 evenly distribute the light transmitted from the light source module and the reflective sheet 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 not only by the claims below but also by the equivalents of the claims.

110: substrate 115: buffer layer
130: first electrode 140: second electrode
150: conductive support substrate 160: ohmic contact area
170: reflective layer 175: bonding layer
180: passivation layer 210: first conductive semiconductor layer
220: electron injection layer 230: active layer
235: electron blocking layer 240: second conductive semiconductor 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 (15)

A light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; And
And an electron injection layer disposed between the first conductivity type semiconductor layer and the active layer and including In.
The well layer and the barrier layer are alternately positioned at least once, and the electron injection layer includes a plurality of sub layers, wherein the energy band gap of the sub layer is wider than the energy band gap of the well layer. The method of claim 1,
The plurality of sub layers includes a sub well layer and a sub barrier layer that are alternately positioned at least once. 3. The method of claim 2,
The sub well layer and the sub barrier layer each have a composition of In _X Ga _{1 - X} N and In _Y Ga _{1 - Y} N (0 <Y <X <1). The method of claim 1,
The well layer of the active layer includes In, and the In content of the sub layer is less than the In content of the well layer. The method of claim 1,
The plurality of sub-layers each have a thickness of 1 ~ 7nm. 3. The method of claim 2,
The first conductive semiconductor layer and the sub-well layer have a light band offset of 0.15 ~ 0.25 eV. 3. The method of claim 2,
The first conductive semiconductor layer and the sub-barrier layer have an energy band offset of 0.088 to 0.15 eV. The method of claim 1,
And a second electrode on the first conductive semiconductor layer and a second electrode on the second conductive semiconductor layer. The method of claim 8,
The second electrode is a light emitting device that is a conductive support substrate. The method of claim 8,
The light emitting structure is positioned on the substrate, the light emitting device is a light extraction pattern is located on the surface of the substrate. The method of claim 9,
At least one of an ohmic contact region and a reflective layer is disposed between the second conductive semiconductor layer and the conductive support substrate. The method of claim 1,
The passivation layer is located on the side of the light emitting structure. The method of claim 1,
The light emitting device further comprises an electron blocking layer between the active layer and the second conductive semiconductor layer. The method of claim 1,
The plurality of sublayers have the same thickness, different thicknesses, or at least two layers having the same thickness. The method of claim 1,
And a roughness pattern positioned on an upper surface of the light emitting structure.

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