KR101960791B1 - Light emitting device - Google Patents

Abstract

A light emitting device according to an embodiment includes a first conductive semiconductor layer; A second conductivity type semiconductor layer; And an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer, the active layer including a plurality of barrier layers and a plurality of well layers disposed alternately with each other, Type semiconductor layer, and a second region located on the first region and adjacent to the second conductive type semiconductor layer, wherein the thickness of the well layer belonging to the first region belongs to the second region It is thicker than the thickness of the well 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.

1 is a diagram showing an energy band diagram of a conventional light emitting device. In the light emitting device, electrons injected from the n-GaN layer and holes injected from the p-GaN layer recombine in the active layer to emit light. 1, the energy band is bent due to the stress caused by the lattice mismatching between the layers, and electrons supplied from the n-GaN layer are not recombined in the active layer and overflowed to the p-GaN layer There is a problem.

Therefore, it is necessary to prevent the electrons from overflowing and increase the recombination rate of electrons and holes in the active layer.

The embodiment attempts to improve the overflow phenomenon of electrons to improve the luminous efficiency of the light emitting device.

A light emitting device according to an embodiment includes a first conductive semiconductor layer; A second conductivity type semiconductor layer; And an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer, the active layer including a plurality of barrier layers and a plurality of well layers disposed alternately with each other, Type semiconductor layer, and a second region located on the first region and adjacent to the second conductive type semiconductor layer, wherein the thickness of the well layer belonging to the first region belongs to the second region It is thicker than the thickness of the well layer.

The first region includes a plurality of well layers, and the plurality of well layers included in the first region may decrease in thickness toward the second conductivity type semiconductor layer.

The plurality of barrier layers may have a constant thickness.

The second region includes a plurality of well layers, and the plurality of well layers included in the second region may have a constant thickness.

The barrier layer belonging to the first region may be thinner than the well layer belonging to the first region.

The barrier layer belonging to the second region may be thinner than the barrier layer belonging to the first region.

The thickness of the well layer belonging to the first region ₁ d _-1, and the thickness of the well layer belonging to the second area d _{2 -1} be when the thickness of the well layer belonging to the first area, d _{1 - 1} d is _{2 -1} <d _{1 -1} ? ₂ d _2-1 .

The two adjacent well layers belonging to the first region may have a thickness difference of 1 nm to 2 nm.

The second conductive semiconductor layer may include an electron blocking layer disposed adjacent to the active layer.

According to the embodiment, it is possible to improve the luminous efficiency of the light emitting device by improving the phenomenon that electrons are overflowed by controlling the movement of electrons.

1 is a view showing an energy band diagram of a conventional light emitting device.
2 is a cross-sectional view of a light emitting device according to one embodiment.
3 is a cross-sectional view of a light emitting device according to another embodiment;
4A and 4B are energy band diagrams of a light emitting device according to the first embodiment.
5 is an energy band diagram of the light emitting device according to the second embodiment.
6 to 8 are diagrams schematically showing an embodiment of a manufacturing process of a light emitting device.
9 is a graph showing the external quantum efficiency (EQE) according to the current density.
FIG. 10 illustrates an embodiment of a light emitting device package including a light emitting device according to embodiments. FIG.
11 is a view illustrating a head lamp in which a light emitting device or a light emitting device package according to embodiments is disposed.
12 is a diagram illustrating a display device in which a light emitting device package according to an embodiment is disposed.

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

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

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

2 is a cross-sectional view of a light emitting device according to an embodiment.

2, the light emitting device 100 includes a first conductive semiconductor layer 122, a second conductive semiconductor layer 126, a first conductive semiconductor layer 122, And an active layer 124 between the two-conductivity-type semiconductor layers 126.

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 device 100 includes an LED (Light Emitting Diode) using a semiconductor layer of a plurality of compound semiconductor layers, for example, a group III-V group element 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 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 may be formed with a multiple quantum well structure by injecting trimethylgallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) But is not limited thereto.

The active layer 124 includes a plurality of well layers 124a and a barrier layer 124b alternately positioned and the well layer 124a / barrier layer 124b of the active layer 124 includes InGaN / GaN, InGaN / InGaN , GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP. The well layer 124a may be formed of a material having a band gap smaller than the band gap of the barrier layer 124b.

The active layer 124 includes a first region 124-1 adjacent to the first conductivity type semiconductor layer 122 and a second region 124-1 located on the first region 124-1 and adjacent to the second conductivity type semiconductor layer 126. [ And a second region 124-2. The first region 124-1 and the second region 124-2 of the active layer 124 will be described later in more detail with reference to FIGS. 4 and 5. FIG.

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.

The second conductive semiconductor layer 126 may include an electron blocking layer (EBL) 126a located adjacent to the active layer 124.

The electron blocking layer 126a has a high mobility of electrons provided in the first conductivity type semiconductor layer 122 so that electrons do 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 126a is formed of a material having an energy band gap larger than the barrier layer 124b of the active layer 124 and is made of In _x Al _y Ga _{1 -xy} N (0? _X <1, 0 <y <1 ). &Lt; / RTI &gt;

The light emitting structure 120 is located 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 115 may be positioned between the light emitting structure 120 and the substrate 110. The buffer layer 115 is intended to alleviate the difference in lattice mismatch and thermal expansion coefficient between the materials of the light emitting structure 120 and the substrate 110. The material of the buffer layer 115 may be at least one of Group III-V compound semiconductors such as GaN, InN, AlN, InGaN, InAlGaN, and AlInN.

An undoped semiconductor layer (not shown) may be disposed between the substrate 110 and the first conductivity type semiconductor layer 122. The un-doped semiconductor layer is a layer formed for improving the crystallinity of the first conductivity type semiconductor layer 122, and has a lower electrical conductivity than that of the first conductivity type semiconductor layer without being doped with an n-type dopant. May be the same as the first conductivity type semiconductor layer 122.

The first conductive semiconductor layer 122 has the exposed surface S exposed by selectively etching at least a portion of the second conductive semiconductor layer 126 and the active layer 124. The first electrode 130 is located on the exposed surface S and the second electrode 140 is located on the un-etched second conductive semiconductor layer 126.

The first electrode 130 and the second electrode 140 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).

The conductive layer 150 may be formed on the second conductive semiconductor layer 126 before the second electrode 140 is formed.

A part of the conductive layer 150 may be opened to expose the second conductive semiconductor layer 126 so that the second conductive semiconductor layer 126 and the second electrode 140 can be in contact with each other.

Alternatively, as shown in FIG. 2, the second conductive semiconductor layer 126 and the second electrode 140 may be electrically connected to each other with the conductive layer 150 therebetween.

The conductive layer 150 may be formed of a layer or a plurality of patterns for improving electrical characteristics of the second conductivity type semiconductor layer 126 and improving electrical contact with the second electrode 140. The conductive layer 150 may be formed of a transparent electrode layer having transparency.

For example, the conductive layer 150 may include a transparent conductive layer and a metal. For example, the conductive layer 150 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 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 100 according to FIG. 2 may have a lateral structure. The horizontal structure means a structure in which the first electrode 130 and the second electrode 140 are formed in the same direction in the light emitting structure 120. Referring to FIG. 2, a first electrode 130 and a second electrode 140 are formed in an upper direction of the light emitting structure 120.

3 is a cross-sectional view of a light emitting device according to another embodiment. The contents overlapping with those described above will not be described again.

Referring to FIG. 3, the light emitting device 100 according to another embodiment includes a first conductive semiconductor layer 122, a second conductive semiconductor layer 126, and a first conductive semiconductor layer 122, And an active layer 124 between the two-conductivity-type semiconductor layers 126.

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 active layer 124 includes a first region 124-1 adjacent to the first conductivity type semiconductor layer 122 and a second region 124-1 located on the first region 124-1 and adjacent to the second conductivity type semiconductor layer 126. [ And a second region 124-2. The first region 124-1 and the second region 124-2 of the active layer 124 will be described later in more detail with reference to FIGS. 4 and 5. FIG.

The first electrode 130 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 220 is located.

As an example, the second electrode layer 220 may include at least one of a conductive layer 220a and a reflective layer 220b.

The conductive layer 220a 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 220a may be formed of a transparent electrode layer or an opaque electrode layer. For example, the conductive layer 220a 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 ), 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 220b may improve the external quantum efficiency of the light emitting device 100 by reducing the amount of light that is emitted from the active layer 124 to thereby cancel out the light emitted from the light emitting device 100. [

The reflective layer 220b may include at least one of Ag, Ti, Ni, Cr, and AgCu, but is not limited thereto.

When the reflective layer 220b is formed of a material that makes an ohmic contact with the second conductive semiconductor layer 126, the conductive layer 220a may not be formed separately.

The light emitting structure 120 is supported by the support substrate 210.

The supporting substrate 210 is formed of a material having high electrical conductivity and high thermal conductivity. For example, the supporting substrate 210 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 support substrate 210 by a bonding layer 215. At this time, the second electrode layer 220 located under the light emitting structure 120 and the bonding layer 215 may be in contact with each other.

The bonding layer 215 includes 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 215 may include a diffusion preventing layer (not shown) adjacent to the light emitting structure 120 so as to prevent the metal or the like used in the bonding layer 215 from diffusing into the upper light emitting structure 120 have.

The channel layer 230 may be positioned around the bottom of the light emitting structure 120. The channel layer 230 protects the light emitting structure 120 and can serve as a stop layer for etching during the isolation process during the manufacturing process of the light emitting device 100. [

The channel layer 230 may be formed in a pattern such as a loop shape, an annular shape, or a frame shape around the bottom of the second conductivity type semiconductor layer 126 of the light emitting structure 120.

The channel layer 230 prevents a short circuit from occurring between the outer walls of the light emitting structure even when exposed to moisture, thereby providing a light emitting device resistant to high humidity.

The channel layer 230 may be selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO) (IGTO), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), SiO2, SiOx, SiOxNy, Si3N4, Al2O3 and TiO2 But the present invention is not limited thereto.

The passivation layer 240 may be located on at least a portion of the light emitting structure 120, the side surface, and the channel layer 230 exposed to the outside of the light emitting structure 120.

The passivation layer 240 may be made of an oxide or a nitride to protect the light emitting structure 120. As an example, the passivation layer 240 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 positioned on the passivation layer 240 when the passivation layer 240 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 100 according to FIG. 3 may have a vertical structure. The vertical structure means a structure in which the first electrode 130 and the second electrode layer 220 are formed in different directions in the light emitting device 100. Referring to FIG. 3, a first electrode 130 is formed in an upper direction of the light emitting structure 120, and a second electrode layer 220 is formed in a lower direction of the light emitting structure 120.

Hereinafter, the first region 124-1 and the second region 124-2 of the active layer 124 will be described in more detail with reference to FIGS. 4 and 5. FIG. The light emitting device according to FIGS. 4 and 5 may be formed in the above-described horizontal structure or vertical structure.

4A and 4B are energy band diagrams of the light emitting device according to the first embodiment.

4A and 4B, the light emitting device 100A according to the first embodiment includes a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126, The active layer 124 includes a plurality of well layers 124a and a plurality of barrier layers 124b alternately positioned.

The first region 124-1 and the second region 124-2 each include at least one well layer 124a and a barrier layer 124b. 4, the first region 124-1 includes a pair of well layers 124a and a barrier layer 124b and the second region 124-2 includes five well layers 124a, And a barrier layer 124b. However, the present invention is not limited thereto.

The active layer 124 includes a first region 124-1 adjacent to the first conductivity type semiconductor layer 122 and a second region 124-1 located on the first region 124-1 and adjacent to the second conductivity type semiconductor layer 126. [ 2 region 124-2 and the thickness d _{1 -1} of the well layer 124a belonging to the first region 124-1 is greater than the thickness d _{1 -1} of the well layer 124a belonging to the second region 124-2 greater than the thickness (d _{2 -1} of _{124a)) (d 1 -1>} d 2 -1).

The thickness d _{1 -1} of the well layer (124a) is, the first area 124-1 thickness of the plurality of well layer (124a) means each having a thickness, and a well layer (124a) belonging to d _{2 - 1} is the Quot; means the thickness of each of the plurality of well layers 124a belonging to the two regions 124-2.

The thickness d _{1 -1} of the well layers 124a belonging to the first region 124-1 is greater than the thickness d _{2 -1} of the well layers 124a belonging to the second region 124-2 because thick is formed below the first area 124-1 of the energy level (EL ₁₎ and a second zone the energy level (EL ₂₎ of (124-2). Accordingly, the mobility of electrons supplied from the first conductivity type semiconductor layer 122 is reduced due to the difference in energy level, so that electrons overflow in the direction of the second conductivity type semiconductor layer 126, And the recombination rate of electrons and holes in the active layer 124 can be increased.

That is, conventionally, since the thickness of the well layer is kept constant in the entire region of the active layer, the banding effect of the energy band and the phenomenon that the electrons overflow in the direction of the second conductivity type semiconductor layer . However, since electrons are controlled to move due to a difference in energy level in the active layer 124, electrons do not overflow and are recombined with holes in the active layer 124, Can be improved.

The first region 124-1 is an area for controlling the movement of electrons and the second region 124-2 may be a region for substantially emitting light by recombination of electrons and holes.

The thickness d _{1 -1} of the well layer 124a belonging to the first region 124-1 is thicker than the thickness d _{2 -1} of the well layer 124a belonging to the second region 124-2 , it may be _{d 2 -1 <d 1 -1 ≤2d} 2 -1. If the thickness d _{1 -1} of the well layer 124a is too small, the difference between the energy level of the second region 124-2 and the energy level of the second region 124-2 may be small, _{1 -1} ) is too large, the crystalline quality of the semiconductor layer may be deteriorated. In the first region 124-1, the plurality of well layers 124a may have a constant thickness d _{1 -1} . As an example, the thickness (d _{1 -1} ) of the plurality of well layers 124a may be between 3 nm and 6 nm, respectively.

The thickness d _{1 -2} of the barrier layer 124b in the first region 124-1 may be less than the thickness d _{1 -1} of the well layer 124a (d _{1 -2} <d _{1 -1} ). The thickness d _{1 -2} of the barrier layer 124b means the thickness of each of the plurality of barrier layers 124b belonging to the first region 124-1. If the thickness (d _{1 -2} ) of the barrier layer 124b is too large, the operating voltage of the light emitting device 100 may increase. The thickness d _{1 -1} of the well layer 124a of the first region 124-1 is thicker than the thickness d _{1 -2} of the barrier layer 124b. For example, d _{1 -2} <d _{1-1 2} d _{1 -2} .

As shown in FIG. 4A, the thickness of the barrier layer 124b belonging to the first region 124-1 and the second region 124-2 may be constant. Alternatively, the barrier belongs to, the first region thickness (d _{1 -2),} a second area (124-2) than that of the barrier layer (124b) belonging to the (124-1) as shown in Figure 4b, in accordance with an embodiment The thickness d _{2 -2} of the layer 124b may be thinner (d _{1 -2} > d _{2 -2} ). The thickness d _{2 -2} of the barrier layer 124b means the thickness of each of the plurality of barrier layers 124b belonging to the second region 124-2. The thickness d _{2 -2} of the barrier layer 124b belonging to the second region 124-2 is smaller than the thickness d _{2 -2} of the barrier layer 124b belonging to the first region 124-1 (D _{1 -2} > d _{2 -2} ), the injection efficiency of holes having mobility significantly lower than that of electrons can be improved.

The plurality of well layers 124a belonging to the second region 124-2 may have a constant thickness d _{2 -1} .

The second region the thickness (d _{2 -1)} in (124-2), the well layer thickness (d _{2 -1)} of (124a) and a barrier layer (124b) the thickness may be the same as, the well layer (124a) May be thinner or thicker than the thickness d _{2 -2} of the barrier layer 124b.

5 is a diagram showing an energy band diagram of the light emitting device according to the second embodiment. The contents overlapping with the above-described embodiments will not be described again, and the differences will be mainly described below.

5, the light emitting device 100B according to the second embodiment includes a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126, and the active layer 124 Includes a plurality of well layers 124a and a plurality of barrier layers 124b alternately positioned.

The active layer 124 includes a first region 124-1 adjacent to the first conductivity type semiconductor layer 122 and a second region 124-1 located on the first region 124-1 and adjacent to the second conductivity type semiconductor layer 126. [ 2 region 124-2 and the thickness d _{1 -1} of the well layer 124a belonging to the first region 124-1 is greater than the thickness d _{1 -1} of the well layer 124a belonging to the second region 124-2 greater than the thickness (d _{2 -1} of _{124a)) (d 1 -1>} d 2 -1).

The first region 124-1 and the second region 124-2 each include at least one well layer 124a and a barrier layer 124b. 5, the first region 124-1 includes a pair of well layers 124a and a barrier layer 124b and the second region 124-2 includes five well layers 124a. And a barrier layer 124b. However, the present invention is not limited thereto.

The thickness d _{1 -1} of the plurality of well layers 124a belonging to the first region 124-1 may decrease toward the direction of the second conductivity type semiconductor layer 126. In this way, the first area 124-1 is gradually increased energy level (EL ₁₎ within and, by the difference in the energy level by gradually controlling the movement of electrons, the electrons do not overflow the active layer (124 The light emitting efficiency of the light emitting device 100 can be improved.

Although it is shown in FIG. 5 that the thickness (d _{1 -1} ) continuously varies in all three well layers 124a belonging to the first region 124-1, according to the embodiment, 126 toward the thickness (d _{1 -1)} is reduced, but at least the adjacent thickness (d _{1 -1)} of the two well layers (124a) in the direction of the may also be constant.

As an example, the difference between the thickness d _{1-1 of} two adjacent well layers 124a belonging to the first region 124-1 may be between 1 nm and 2 nm. That is, when the thickness d _{1 -1} of the adjacent two well layers 124a belonging to the first region 124-1 decreases toward the direction of the second conductivity type semiconductor layer 126, And may have a width of 1 nm to 2 nm.

In addition, the thickness of the well layer (124a) belonging to the first area 124-1 of the thickness (d _{1 -1)} and the barrier layer (124b), (d _{1 -2)} between the first region between the (124- The relationship between the thickness d _1-1 of the well layer 124a belonging to the first region 124-1 and the thickness d _{-2 -1} of the well layer 124a belonging to the second region 124-2, -1) and the thicknesses (d _{2 -1} , d _{2 -2} ) of the plurality of barrier layers 124b belonging to the second region 124-2 are as described above with reference to FIG. 4, It is omitted.

FIGS. 6 to 8 are views schematically showing an embodiment of a manufacturing process of a light emitting device.

First, referring to FIG. 6, a first conductive semiconductor layer 122 and an active layer 124 are grown on a substrate 110. In order to improve the crystallinity of the light emitting structure 120, the buffer layer 115 may be grown on the substrate 110, and then the first conductivity type semiconductor layer 122 may be grown.

The first conductive semiconductor layer 122 and the active layer 124 and the semiconductor layers thereafter may be formed using a metal organic chemical vapor deposition (MOCVD) method, a chemical vapor deposition (CVD) method, a plasma May be grown by a method such as chemical vapor deposition (PECVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE) Not limited.

The active layer 124 may have a multi-well structure including a plurality of well layers 124a and a barrier layer 124b alternately. At this time, the first region 124-1 is formed by growing the well layer 124a to be somewhat thick at the portion adjacent to the first conductivity type semiconductor layer 122, and thereafter, A well layer 124a having a thickness smaller than that of the well layer 124a is grown to form a second region 124-2.

In the first region 124-1 of the active layer 124, the barrier layer 124b may be formed to be thinner than the well layer 124a. If the thickness of the barrier layer 124b is reduced, the quality of the semiconductor layer may be deteriorated. However, by growing the barrier layer 124b at a temperature higher than the growth temperature of the well layer 124a, a high quality barrier layer 124b is formed can do.

In FIG. 6, eight well layers 124a and barrier layers 124b are formed as one example, and the remaining three periods are the first regions 124-1 and the remaining five periods are the second regions 124- 2).

The second conductive semiconductor layer 126 may be grown on the active layer 124 to complete the light emitting structure 120.

Referring to FIG. 7, a light emitting device having a horizontal structure can be manufactured by selectively etching the light emitting structure 120.

6, a portion of the second conductivity type semiconductor layer 126, the active layer 124, and the first conductivity type semiconductor layer 122 may be selectively grown after the second conductivity type semiconductor layer 126 is grown, So as to form an exposed surface S. A first electrode 130 is formed on the exposed surface S of the first conductive semiconductor layer 122 and a second electrode 140 is formed on the untreated second conductive semiconductor layer 126 . The conductive layer 150 may be deposited between the second conductive type semiconductor layer 126 and the second electrode 140 according to the manufacturing method.

Alternatively, as shown in Figs. 8A and 8B, a vertical-structured light-emitting device may be fabricated.

Referring to FIG. 8A, after the second conductive semiconductor layer 126 is grown as shown in FIG. 6, a second electrode layer 220 is formed. Then, the channel layer 230 is formed by removing a part of the second electrode layer 220 in a region to be diced with an individual light emitting device.

Thereafter, the supporting substrate 210 is disposed on the second electrode layer 220. The supporting substrate 210 may be formed by a bonding method, a plating method, or a deposition method. When the supporting substrate 210 is formed by a bonding method, the second electrode layer 220 and the supporting substrate 210 may be bonded through the bonding layer 215.

Then, as shown in Fig. 8A, the substrate 110 is separated. The substrate 110 may be separated by a laser lift off (LLO) method using an excimer laser or the like, or may be a dry or wet etching method.

When excimer laser light having a wavelength in a certain region in the direction of the substrate 110 is focused and irradiated using the laser lift-off method, heat energy is applied to the interface between the substrate 110 and the light emitting structure 120 The interface is separated into gallium and nitrogen molecules, and the substrate 110 is instantaneously separated from the laser light passing portion. After the substrate 110 is removed, the buffer layer 115 may be removed through a separate etching process.

8B, isolation etching is performed in a region where the channel layer 230 is located, and is separated into the respective light emitting device units. The isolation etching can be performed by, for example, a dry etching method such as ICP (Inductively Coupled Plasma).

The first electrode 130 is formed on the first conductivity type semiconductor layer 122 of the light emitting structure 120. [ A passivation layer 240 is formed on at least a part of the upper surface and the side surface of the light emitting structure 120.

The manufacturing process of the light emitting device 100 is merely an example, and the order and method of a specific manufacturing process may be changed according to the embodiment.

9 is a graph showing the external quantum efficiency (EQE) according to the current density.

The comparative example shows a conventional light emitting device in which the thickness of the well layer is constant over the entire active layer, and the embodiment shows the light emitting device according to the above-described second embodiment.

Referring to FIG. 9, it can be seen that the luminous efficiency of the light emitting device is improved according to the embodiment, and the luminous efficiency is improved especially at the high current density.

10 is a view showing an embodiment of a light emitting device package including the light emitting device according to the embodiments.

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.

11 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.

11, the 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 on a circuit board, but the present invention is not limited thereto.

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

12, the display device 800 according to the embodiment includes the light emitting modules 830 and 835, the reflection plate 820 on the bottom cover 810, and the reflection plate 820 disposed on the front side 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, a PCB or the like may be used for the circuit board 830, and the light emitting device package 835 is as described with reference to FIG.

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

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

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

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

In the second prism sheet 860, the edges and the valleys on one surface of the support film may be perpendicular to the edges and the valleys on one surface of the support film in the first prism sheet 850. This is to 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.

100: light emitting device 110: substrate
120: light emitting structure 122: first conductivity type semiconductor layer
124: second conductivity type semiconductor layer 124a: well layer
124b: barrier layer 124-1: first region
124-2: second region 126: second conductivity type semiconductor layer
126a: electron blocking layer 210: supporting substrate
220: second electrode layer 240: passivation 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 (9)

A first conductive semiconductor layer;
A second conductivity type semiconductor layer; And
And an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer and including a plurality of barrier layers and a plurality of well layers alternately disposed,
The active layer includes a first region adjacent to the first conductive type semiconductor layer and a second region located on the first region and adjacent to the second conductive type semiconductor layer,
Wherein a thickness of the plurality of well layers belonging to the first region is thicker than a thickness of the barrier layer belonging to the first region,
The plurality of well layers belonging to the first region are thicker than the well layers belonging to the second region,
The plurality of well layers belonging to the first region decrease in thickness toward the direction of the second conductivity type semiconductor layer,
Wherein the plurality of well layers included in the second region are constant in thickness,
The energy level in the first region gradually increases,
The energy level in the first region is lower than the energy level in the second region,
When the thickness of the well layer belonging to the first region is d _1-1 and the thickness of the well layer belonging to the second region is d _2-1 , the thickness d _1-1 of the well layer belonging to the first region is d _2-1 < d _1-1 ? ₂ d _2-1 . delete The method according to claim 1,
Wherein the plurality of barrier layers have a constant thickness. delete delete delete delete The method according to claim 1,
And the adjacent two well layers belonging to the first region have a thickness difference of 1 nm to 2 nm. delete

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