KR20140092091A - Light emitting device - Google Patents

Light emitting device Download PDF

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Publication number
KR20140092091A
KR20140092091A KR1020130004397A KR20130004397A KR20140092091A KR 20140092091 A KR20140092091 A KR 20140092091A KR 1020130004397 A KR1020130004397 A KR 1020130004397A KR 20130004397 A KR20130004397 A KR 20130004397A KR 20140092091 A KR20140092091 A KR 20140092091A
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South Korea
Prior art keywords
layer
light emitting
semiconductor layer
emitting device
electron blocking
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KR1020130004397A
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Korean (ko)
Inventor
심세환
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엘지이노텍 주식회사
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Priority to KR1020130004397A priority Critical patent/KR20140092091A/en
Publication of KR20140092091A publication Critical patent/KR20140092091A/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/025—Physical imperfections, e.g. particular concentration or distribution of impurities
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/14—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
    • H01L33/145—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure with a current-blocking structure

Abstract

Disclosed is a light emitting device with improved electrical properties and luminous intensity. The light emitting device according to an embodiment of the present invention includes a first conductive semiconductor layer; a second conductive semiconductor layer; an active layer which is arranged between the first conductive semiconductor layer and the second conductive semiconductor layer; and an electron blocking layer which is arranged between the active layer and the second conductive semiconductor layer. The second conductive semiconductor layer includes a first layer in contact with the electron blocking layer and a second layer which is arranged on the upper side of the first layer. The energy bandgap of the first layer is smaller than the energy bandgap of the second layer.

Description

[0001] LIGHT EMITTING DEVICE [0002]

An embodiment relates to a light emitting element.

BACKGROUND ART Light emitting devices such as light emitting diodes and laser diodes using semiconductor materials of Group 3-5 or 2-6 group semiconductors have been 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.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically illustrating an energy band diagram of a conventional light emitting device. FIG.

1, the conventional light emitting device 1 includes an n-GaN layer, an active layer (MQW), and a p-GaN layer. The electrons injected from the n-GaN layer and holes injected from the p- And recombines in the active layer (MQW) to emit light. In order to prevent the electrons from being recombined with the holes in the active layer (MQW) and overflowing into the p-GaN layer, electrons have an energy band between the active layer (MQW) and the p-GaN layer The electron blocking layer EBL having a large gap is disposed. At this time, Mg is generally doped in the electron blocking layer (EBL) to improve the injection efficiency of holes into the active layer (MQW).

The material mainly used as the electron blocking layer (EBL) is AlGaN, and AlGaN has a large lattice constant difference from the active layer (MQW) material, and thus a pit is induced in the electron blocking layer (EBL). These pits lower the luminous efficiency and luminous efficiency of the light emitting device and also affect the electrical characteristics. Further, the injection efficiency of holes is lowered due to the reduction of the doping efficiency of Mg due to Al. If Mg is excessively doped in the electron blocking layer (EBL) to prevent this, the crystallinity of the electron blocking layer (EBL) deteriorates.

Embodiments provide a light emitting device having improved electrical characteristics and brightness.

A light emitting device according to an embodiment includes a first conductive semiconductor layer; A second conductivity type semiconductor layer; An active layer between the first conductive semiconductor layer and the second conductive semiconductor layer; And an electron blocking layer between the active layer and the second conductive type semiconductor layer, wherein the second conductive type semiconductor layer includes a first layer in contact with the electron blocking layer and a second layer in contact with the electron blocking layer, And the first layer has a smaller energy band gap than the second layer.

Wherein the active layer includes a well layer and a plurality of pairs of barrier layers having a larger energy bandgap than the well layer, the first layer being formed between the energy band gap of the well layer and the energy band gap of the second layer Energy bandgap.

The first layer may have a thickness of 3 nm to 15 nm.

The first layer may be thinner than the second layer.

The electron blocking layer may include a plurality of pairs of a first electron blocking layer and a second electron blocking layer having a smaller energy bandgap than the first electron blocking layer.

The first layer may have a smaller energy bandgap than the second electron blocking layer.

According to the embodiment, the efficiency of injecting holes is improved and the crystallinity of the electron blocking layer and the second conductivity type semiconductor layer is improved, so that the electrical characteristics and brightness of the light emitting device can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows an energy band diagram of a conventional light emitting device. FIG.
2 is a view illustrating an example of a light emitting device according to an embodiment.
3 is a view showing another example of the light emitting device according to the embodiment.
4 is a diagram schematically illustrating an energy band diagram of a light emitting device according to the first embodiment;
5 is a view schematically showing an energy band diagram of a light emitting device according to a second embodiment.
6 is a graph showing external quantum efficiency of the light emitting device according to the first embodiment compared with a conventional light emitting device.
FIG. 7 illustrates an embodiment of a light emitting device package including a light emitting device according to embodiments. FIG.
8 is a view illustrating an embodiment of a headlamp in which a light emitting device or a light emitting device package according to embodiments is disposed.
9 is a view illustrating a display device in which a light emitting device package according to an embodiment is disposed.

Embodiments will now 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.

2 is a view illustrating an example of a light emitting device according to an embodiment.

2, a light emitting device 100A according to an exemplary embodiment includes a first conductive semiconductor layer 122, a second conductive semiconductor layer 126, a first conductive semiconductor layer 122, Type semiconductor layer 126 and an electron blocking layer 130 between the active layer 124 and the second conductivity type semiconductor layer 126.

The light emitting device 100A includes an LED (Light Emitting Diode) using a semiconductor layer of a plurality of compound semiconductor layers, for example, a Group III-V or a Group II-VI element, and the LED includes blue, green or red A colored LED emitting the same light, or a white LED or a UV LED. The emitted light of the LED may be implemented using various semiconductors, but is not limited thereto.

The first conductive semiconductor layer 122, the active layer 124, and the second conductive semiconductor layer 126 may be combined to form the light emitting structure 120.

The light emitting structure 120 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 122 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 conductivity type semiconductor layer 122 is an n-type semiconductor layer, the first conductivity type dopant may include Si, Ge, Sn, Se, and Te as an n-type dopant, but is not limited thereto. When the second conductive semiconductor layer 122 is a p-type semiconductor layer, the first conductive dopant may include Mg, Zn, Ca, Sr, and Ba as p-type dopants, but is not limited thereto.

The first conductive semiconductor layer 122 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.

The second conductive semiconductor layer 126 may be formed of a semiconductor compound, and may be formed of a compound semiconductor such as a Group 3-Group 5 or a Group 2-Group 6, for example. The second conductivity type dopant may also be doped. The second conductivity type semiconductor layer 126 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 126 is a p-type semiconductor layer, the second conductive dopant may include Mg, Zn, Ca, Sr, and Ba as p-type dopants, but is not limited thereto. When the second conductive semiconductor layer 126 is an n-type semiconductor layer, the second conductive dopant may include Si, Ge, Sn, Se, Te, or the like as the n-type dopant, but is not limited thereto.

Hereinafter, the case where the first conductivity type semiconductor layer 122 is an n-type semiconductor layer and the second conductivity type semiconductor layer 126 is a p-type semiconductor layer will be described as an example.

An n-type semiconductor layer (not shown) may be formed on the second conductive type semiconductor layer 126 when the semiconductor having the opposite polarity to the second conductive type, for example, the second conductive type semiconductor layer is a p- have. 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 active layer 124 is positioned between the first conductive semiconductor layer 122 and the second conductive semiconductor layer 126.

The active layer 124 is a layer in which electrons and holes meet each other to emit light having energy determined by the energy band inherent in the active layer (light emitting layer) material. When the first conductivity type semiconductor layer 122 is an n-type semiconductor layer and the second conductivity type semiconductor layer 126 is a p-type semiconductor layer, electrons are injected from the first conductivity type semiconductor layer 122, Holes can be injected from the conductive semiconductor layer 126. [

The active layer 124 may be formed in a multi-well structure. For example, the active layer 124 is formed by implanting trimethyl gallium gas (TMGa), ammonia gas (NH 3 ), nitrogen gas (N 2 ), and trimethyl indium gas (TMIn) to form a multiple quantum well (MQW) But is not limited thereto.

InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs / InGaAs), and InGaN / ) / AlGaAs, GaP (InGaP) / AlGaP, but the present invention is not limited thereto. The well layer may be formed of a material having an energy band gap smaller than the energy band gap of the barrier layer.

A conductive clad layer (not shown) may be formed on and / or below the active layer 124. 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.

An electron blocking layer 130 is disposed between the active layer 124 and the second conductive semiconductor layer 126.

The electron blocking layer 130 has a high mobility of electrons provided from the first conductivity type semiconductor layer 122 so that electrons can not contribute to light emission and the second conductivity type semiconductor layer 126) to prevent the leakage current from being generated.

The electron blocking layer 130 is formed of a material having a larger energy band gap than the barrier layer of the active layer 124 and has a composition of In x Al y GaN 1 -xy (0? X <1, 0 <y < .

The second conductive semiconductor layer 126 includes a first layer 126-1 contacting the electron blocking layer 130 and a second layer 126-2 disposed on the first layer 126-1. . The first layer 126-1 is formed of a material having a smaller energy band gap than the second layer 126-2.

The first layer 126-1 and the second layer 126-2 of the electron blocking layer 130 and the second conductivity type semiconductor layer 126 will be described later in more detail with reference to FIGS. do.

The light emitting structure 120 is disposed on the substrate 110.

The substrate 110 may be formed of a material having excellent thermal conductivity, which is suitable for semiconductor material growth. At least one of sapphire (Al 2 O 3 ), SiC, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga 2 O 3 may be used as the substrate 110. The substrate 110 may be wet-cleaned to remove impurities on the surface.

A buffer layer 112 may be disposed between the light emitting structure 120 and the substrate 110. The buffer layer 112 is intended to alleviate the difference in lattice mismatching and thermal expansion coefficient between the materials of the light emitting structure 120 and the substrate 110. The material of the buffer layer 112 may be at least one of Group III-V compound semiconductors such as GaN, InN, AlN, InGaN, InAlGaN, and AlInN.

The undoped semiconductor layer 114 may be positioned between the substrate 110 and the first conductivity type semiconductor layer 122. [ The un-doped semiconductor layer 114 is formed to improve the crystallinity of the first conductivity type semiconductor layer 122, and is not doped with the n-type dopant and thus has a lower electrical conductivity than the first conductivity type semiconductor layer And may be the same as the first conductivity type semiconductor layer 122. The undoped semiconductor layer 114 may be disposed in contact with the first semiconductor layer 122 at an upper portion of the buffer layer 112. The undoped semiconductor layer 114 grows at a temperature higher than the growth temperature of the buffer layer 112 and exhibits better crystallinity than the buffer layer 112.

The first conductive semiconductor layer 122 has the exposed surface S exposed by selectively etching the second conductive semiconductor layer 126 and a part of the active layer 124. The first electrode 140 is located on the exposed surface S and the second electrode 142 is located on the unetched second conductive semiconductor layer 126.

The first electrode 140 and the second electrode 142 may be formed of at least one selected from the group consisting of Mo, Cr, Ni, Au, Al, Ti, Pt, Layer structure including at least one of tungsten (V), tungsten (W), lead (Pd), copper (Cu), rhodium (Rh) or iridium (Ir).

A conductive layer 144 may be formed on the second conductive semiconductor layer 126 before the second electrode 142 is formed.

A part of the conductive layer 144 may be opened to expose the second conductive semiconductor layer 126 so that the second conductive semiconductor layer 126 and the second electrode 142 may be in contact with each other.

Alternatively, as shown in FIG. 2, the second conductive semiconductor layer 126 and the second electrode 142 may be electrically connected with the conductive layer 144 therebetween.

The conductive layer 144 may be formed of a layer or a plurality of patterns for improving electrical characteristics of the second conductive type semiconductor layer 126 and for improving electrical contact with the second electrode 142. The conductive layer 144 may be formed of a transparent electrode layer having light transmittance.

The conductive layer 144 may be formed of a light-transmitting conductive layer and a metal. For example, the conductive layer 144 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO) ), 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.

The light emitting device 100A according to FIG. 2 may have a lateral structure. The horizontal structure means a structure in which the first electrode 140 and the second electrode 142 are formed in the same direction in the light emitting structure 120. Referring to FIG. 2, a first electrode 140 and a second electrode 142 are formed in an upper direction of the light emitting structure 120.

3 is a view showing another example of the light emitting device according to the embodiment. The contents overlapping with the above-mentioned contents will not be described again, and the following description will focus on the differences.

Referring to FIG. 3, the light emitting device 100B according to another exemplary embodiment includes a first conductive semiconductor layer 122, a second conductive semiconductor layer 126, a first conductive semiconductor layer 122, Type semiconductor layer 126 and an electron blocking layer 130 between the active layer 124 and the second conductivity type semiconductor layer 126.

The light emitting device 100B includes an LED (Light Emitting Diode) using a semiconductor layer of a plurality of compound semiconductor layers, for example, a Group III-V or a Group II-VI element, and the LED includes blue, green, A colored LED emitting the same light, or a white LED or a UV LED. The emitted light of the LED may be implemented using various semiconductors, but is not limited thereto.

The first conductive semiconductor layer 122, the active layer 124, and the second conductive semiconductor layer 126 may be combined to form the light emitting structure 120.

The second conductive semiconductor layer 126 may include a first layer 126-1 contacting the electron blocking layer 130 and a second layer 126-2 disposed below the first layer 126-1. . The first layer 126-1 is formed of a material having a smaller energy band gap than the second layer 126-2.

The first layer 126-1 and the second layer 126-2 of the electron blocking layer 130 and the second conductivity type semiconductor layer 126 will be described later in more detail with reference to FIGS. do.

The first electrode 140 is located on the upper surface of the light emitting structure 120 or the first conductive semiconductor layer 122 and the lower surface of the light emitting structure 120, The second electrode layer 150 is located.

As an example, the second electrode layer 150 may include at least one of a conductive layer 150a and a reflective layer 150b.

The conductive layer 150a is provided to improve the electrical characteristics of the second conductivity type semiconductor layer 126 and may be in contact with the second conductivity type semiconductor layer 126. [

The conductive layer 150a may be formed of a transparent electrode layer or an opaque electrode layer. For example, the conductive layer 150a may include indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO) , IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON ), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au or Ni / IrOx / Au / ITO, Ag, Ni, Cr, Ti, , Ir, Sn, In, Ru, Mg, Zn, Pt, Au, and Hf.

The reflective layer 150b may improve the external quantum efficiency of the light emitting device 100B by reducing the amount of light that is extinguished inside the light emitting device 100B by reflecting the light generated in the active layer 124. [

The reflective layer 150b may include at least one of Ag, Ti, Ni, Cr, and AgCu, but is not limited thereto.

When the reflective layer 150b is formed of a material that makes an ohmic contact with the second conductive type semiconductor layer 126, the conductive layer 150a may not be formed separately.

The light emitting structure 120 is supported by the supporting substrate 160.

The supporting substrate 160 is formed of a material having high electrical conductivity and high thermal conductivity. For example, the supporting substrate 160 may be a base substrate having a predetermined thickness, such as molybdenum (Mo), silicon (Si), tungsten (W) (Au), a copper alloy (Cu Alloy), a nickel (Ni), a copper-tungsten (Cu-Al) alloy, or a material selected from the group consisting of copper (Cu) W), carrier wafer (for example, a GaN, Si, Ge, GaAs, ZnO, SiGe, SiC, SiGe, Ga 2 O 3 , etc.) or a conductive sheet or the like may optionally be included.

The light emitting structure 120 may be bonded to the supporting substrate 160 by a bonding layer 165. At this time, the second electrode layer 150 located under the light emitting structure 120 and the bonding layer 165 may be in contact with each other.

The bonding layer 165 may include a barrier metal or a bonding metal and may include at least one of Ti, Au, Sn, Ni, Cr, Ga, In, Bi, Cu, Ag, It is not limited thereto.

The bonding layer 165 may include a diffusion preventing layer (not shown) adjacent to the light emitting structure 120 to prevent the metal or the like used in the bonding layer 165 from diffusing into the upper light emitting structure 120 have.

The passivation layer 170 may be located on at least a portion and / or a side of the light emitting structure 120.

The passivation layer 170 may be made of an oxide or a nitride to protect the light emitting structure 120. As an example, the passivation layer 170 may comprise, but is not limited to, a silicon oxide (SiO 2 ) layer, a silicon nitride layer, an oxynitride layer, or an aluminum oxide layer.

The roughness pattern R may be formed on the first conductivity type semiconductor layer 122 of the light emitting structure 120. [ The roughness pattern R may be located on the passivation layer 170 when the passivation layer 170 is present on the upper side of the light emitting structure 120. The roughness pattern R can be formed by performing an etching process using a PEC (Photo Enhanced Chemical) etching method or a mask pattern. The roughness pattern R is for increasing the external extraction efficiency of light generated in the active layer 124, and may have a regular period or an irregular period.

The light emitting device 100B according to FIG. 3 may have a vertical structure. The vertical structure means a structure in which the first electrode 140 and the second electrode layer 150 are formed in different directions in the light emitting structure 120. Referring to FIG. 3, a first electrode 140 is formed in an upper direction of the light emitting structure 120, and a second electrode layer 150 is formed in a lower direction of the light emitting structure 120.

Hereinafter, the first layer 126-1 and the second layer 126-2 of the electron blocking layer 130 and the second conductivity type semiconductor layer 126 will be described in more detail with reference to FIGS. 4 and 5 do. The light emitting device according to FIGS. 4 and 5 may be formed in the above-described horizontal structure or vertical structure.

4 is a diagram schematically illustrating an energy band diagram of a light emitting device according to the first embodiment. The contents overlapping with the above-mentioned contents will not be described again, and the following description will focus on the differences.

Referring to FIG. 4, the light emitting device 100-1 according to the first embodiment includes a first conductive semiconductor layer 122, a second conductive semiconductor layer 126, a first conductive semiconductor layer 122, An active layer 124 between the active layer 124 and the second conductive semiconductor layer 126 and an electron blocking layer 130 between the active layer 124 and the second conductive semiconductor layer 126.

The second conductive semiconductor layer 126 includes a first layer 126-1 contacting the electron blocking layer 130 and a second layer 126-2 disposed on the first layer 126-1. . The second layer 126-2 is disposed apart from the electron blocking layer 130.

The first layer 126-1 is made of a material having an energy band gap smaller than that of the second layer 126-2. The energy band gap between the first layer 126-1 and the second layer 126-2 can be controlled by the content of In or Al. When the content of In increases, the energy bandgap decreases. When the content of Al increases, the energy bandgap increases. Since the energy band gap of the first layer 126-1 is smaller than the energy band gap of the second layer 126-2, the first layer 126-1 may include In. The second layer 126-2 may not include In, or may comprise less In than the first layer 126-1. Depending on the embodiment, the second layer 126-2 may comprise Al, or may not include Al.

The first layer 126-1 serves as a hole trapping layer for trapping holes provided in the second layer 126-2. The first layer 126-1 may trap holes provided in the second layer 126-2 using a structure having a smaller energy band gap than the second layer 126-2 and may supply the active layer 124 with holes have. According to the embodiment, the injection efficiency of holes is improved because holes trapped in the first layer 126-1 can be supplied to the active layer 124 through the electron blocking layer 130 by tunneling . Further, since the second conductive dopant such as Mg is not over-doped to the electron blocking layer 130 to improve the hole injection efficiency, the electron blocking layer 130 and the second conductive semiconductor layer 126 ) Is improved, and as a result, the electrical characteristics and brightness of the light emitting device can be improved.

The first layer 126-1 is formed to be thinner than the second layer 126-2. According to an embodiment, the thickness D of the first layer 126-1 may be between 3 nm and 15 nm. If the first layer 126-1 is formed to be thinner than 3 nm, the function of the hole trapping layer may not be enhanced, and if the first layer 126-1 is thicker than 15 nm, the operation voltage of the light emitting device 100-1 may be increased.

The active layer 124 may include a plurality of pairs of well layers 124a and barrier layers 124b having a larger energy bandgap than the well layers 124b. The first layer 126-1 may have an energy bandgap between the energy band gap of the well layer 124a of the active layer 124 and the energy band gap of the second layer 126-2.

5 is a diagram schematically illustrating an energy band diagram of a light emitting device according to the second embodiment. The contents overlapping with the above-mentioned contents will not be described again, and the following description will focus on the differences.

5, the light emitting device 100-2 according to the second embodiment includes a first conductive semiconductor layer 122, a second conductive semiconductor layer 126, a first conductive semiconductor layer 122, An active layer 124 between the active layer 124 and the second conductive semiconductor layer 126 and an electron blocking layer 130 between the active layer 124 and the second conductive semiconductor layer 126.

The second conductive semiconductor layer 126 includes a first layer 126-1 contacting the electron blocking layer 130 and a second layer 126-2 disposed on the first layer 126-1. . The second layer 126-2 is disposed apart from the electron blocking layer 130.

The first layer 126-1 is made of a material having an energy band gap smaller than that of the second layer 126-2. The energy band gap between the first layer 126-1 and the second layer 126-2 can be controlled by the content of In or Al. When the content of In increases, the energy bandgap decreases. When the content of Al increases, the energy bandgap increases. Since the energy band gap of the first layer 126-1 is smaller than the energy band gap of the second layer 126-2, the first layer 126-1 may include In. The second layer 126-2 may not include In, or may comprise less In than the first layer 126-1. Depending on the embodiment, the second layer 126-2 may comprise Al, or may not include Al.

The first layer 126-1 is formed to be thinner than the second layer 126-2. According to an embodiment, the thickness D of the first layer 126-1 may be between 3 nm and 15 nm. If the first layer 126-1 is formed to be thinner than 3 nm, the function of the hole trapping layer may not be enhanced, and if the first layer 126-1 is thicker than 15 nm, the operation voltage of the light emitting device 100-1 may be increased.

The active layer 124 may include a plurality of pairs of well layers 124a and barrier layers 124b having a larger energy bandgap than the well layers 124b. The first layer 126-1 may have an energy bandgap between the energy band gap of the well layer 124a of the active layer 124 and the energy band gap of the second layer 126-2.

The electron blocking layer 130 has a pair structure of the first electron blocking layer 130-1 and the second electron blocking layer 130-2 having a smaller energy bandgap than the first electron blocking layer 130-1, . The number of pairs of the first electron blocking layer 130-1 and the second electron blocking layer 130-2 may vary depending on the embodiment. The electron blocking layer 130 is formed of a plurality of pairs of structures including the first electron blocking layer 130-1 and the second electron blocking layer 130-2 so that the light output of the light emitting element 100-2 is improved .

According to the embodiment, the first layer 126-1 may have a smaller energy bandgap than the second electron blocking layer 130-2. The thickness D of the first layer 126-1 is formed to be greater than the thickness of each of the first electron blocking layer 130-1 or each of the second electron blocking layer 130-2.

6 is a graph showing the external quantum efficiency of the light emitting device according to the first embodiment compared with the conventional light emitting device.

6, it can be seen that the external quantum efficiency (EQE) is improved in the case of the light emitting device B according to the first embodiment as compared with the conventional light emitting device A without the hole trapping layer have. The efficiency of injection of holes is improved by the first layer 126-1 of the second conductivity type semiconductor layer 126 and the electron blocking layer 130 and the second conductivity type semiconductor layer 126 are formed, The crystallinity quality of the light emitting device is improved and the luminous intensity of the light emitting device is improved.

FIG. 7 illustrates a light emitting device package including a light emitting device according to embodiments. Referring to FIG.

The light emitting device package 300 according to an exemplary embodiment includes a body 310, a first lead frame 321 and a second lead frame 322 disposed on the body 310, Emitting device 100 according to the above-described embodiments electrically connected to the first lead frame 321 and the second lead frame 322, and a molding part 340 formed in the cavity. A cavity may be formed in the body 310.

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 disposed on the body 310 or may be disposed 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 phosphor 350 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.

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

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

8, light emitted from the light emitting module 710 having the light emitting device or the light emitting device package according to the embodiments is reflected by the reflector 720 and the shade 730 and then transmitted through the lens 740 It can be directed toward the front of the vehicle body.

The light emitting module 710 may include a plurality of light emitting devices or light emitting device packages on a circuit board, but the present invention is not limited thereto.

FIG. 9 is a diagram 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 emitting module 830 and 835, a reflection plate 820 on the bottom cover 810, and a reflection plate 820 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 emitting 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 as described above.

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 uniformly distribute the light transmitted from the light emitting 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 by the equivalents of the claims, as well as the claims.

100A, 100B, 100-1, 100-2: light emitting element 122: first conductivity type semiconductor layer
124: active layer 126: second conductivity type semiconductor layer
126-1: first layer 126-2: second layer
130: electron blocking layer 130-1: first electron blocking layer
130-2: a second electron blocking layer

Claims (6)

A first conductive semiconductor layer;
A second conductivity type semiconductor layer;
An active layer between the first conductive semiconductor layer and the second conductive semiconductor layer; And
And an electron blocking layer between the active layer and the second conductive type semiconductor layer,
Wherein the second conductive semiconductor layer includes a first layer in contact with the electron blocking layer and a second layer disposed on the first layer, wherein the first layer has a smaller energy band gap than the second layer device. The method according to claim 1,
Wherein the active layer includes a plurality of pairs of barrier layers having a well layer and a barrier layer having a larger energy bandgap than the well layer,
Wherein the first layer has an energy band gap between the energy band gap of the well layer and the energy band gap of the second layer. The method according to claim 1,
Wherein the first layer has a thickness of 3 nm to 15 nm. The method according to claim 1,
Wherein the first layer is thinner than the second layer. The method according to claim 1,
Wherein the electron blocking layer comprises a plurality of pairs of a first electron blocking layer and a second electron blocking layer having a smaller energy bandgap than the first electron blocking layer. 6. The method of claim 5,
Wherein the first layer has a smaller energy band gap than the second electron blocking layer.
KR1020130004397A 2013-01-15 2013-01-15 Light emitting device KR20140092091A (en)

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