KR20130012428A

KR20130012428A - Light emitting device

Info

Publication number: KR20130012428A
Application number: KR1020110073631A
Authority: KR
Inventors: 나종호; 홍훈기; 이현기
Original assignee: 엘지이노텍 주식회사
Priority date: 2011-07-25
Filing date: 2011-07-25
Publication date: 2013-02-04

Abstract

The light emitting device according to the embodiment includes a light emitting structure including a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer, wherein among the first semiconductor layer and the second semiconductor layer, At least one is a P-type semiconductor layer doped with a P-type dopant, the active layer includes a well layer and a barrier layer, the well layer includes a first well layer and a second well layer closest to the P-type semiconductor layer, The first well layer has a first band gap, the second well layer has a second band gap smaller than the first band gap, and the thickness of the first well layer is formed thicker than the thickness of the second well layer.

Description

[0001]

An embodiment relates to a light emitting element.

LED (Light Emitting Diode) is a device that converts electrical signals into infrared, visible light or light using the characteristics of compound semiconductors. It is used in household appliances, remote controls, display boards, The use area of LED is becoming wider.

In general, miniaturized LEDs are made of a surface mounting device for mounting directly on a PCB (Printed Circuit Board) substrate, and an LED lamp used as a display device is also being developed as a surface mounting device type . Such a surface mount device can replace a conventional simple lighting lamp, which is used for a lighting indicator for various colors, a character indicator, an image indicator, and the like.

As the use area of the LED is widened as described above, it is important to increase the luminance of the LED as the brightness required for a lamp used in daily life and a lamp for a structural signal is increased.

In Patent Publication No. 10-2008-0045943, between the n-type nitride semiconductor layer and the active layer, the band gap energy is lower than the band gap energy of the adjacent quantum barrier layer of the n-type nitride semiconductor layer and quantum barrier layer, AlaYbGa1- A light emitting device including an electron injection layer made of a-bN (where a is 0 ≦ a ≦ 1 and b satisfies 0 <b ≦ 1) is disclosed. The electron injection efficiency may be improved by forming the electron injection layer, but since the mobility of holes is smaller than that of electrons, it is necessary to improve the hole injection efficiency.

Embodiments provide a light emitting device having improved light emission efficiency and crystal defects.

The light emitting device according to the embodiment includes a light emitting structure including a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer, wherein the first semiconductor layer is doped with a P-type dopant. P-type semiconductor layer, the active layer includes a well layer and a barrier layer alternately stacked, the barrier layer includes a first barrier layer, and a second barrier layer disposed between the first barrier layer and the first semiconductor layer. And the second barrier layer comprises a first layer and a second layer disposed between the first layer and the first semiconductor layer, the first layer having a first bandgap, and the second layer having a second bandgap The second band gap is smaller than the first band gap.

In the light emitting device according to the embodiment, the hole injection efficiency of the active layer is improved, thereby improving luminous efficiency and crystal defects.

1 is a view showing a light emitting device according to an embodiment;
2 is a partially enlarged cross-sectional view of a light emitting device according to the embodiment;
3 is a diagram showing an energy band diagram of a light emitting device according to an embodiment;
4 is a view showing a difference in luminance between the light emitting device according to the prior art and the light emitting device according to the embodiment;
5 is a view showing a difference in operating voltage between a light emitting device according to the prior art and a light emitting device according to an embodiment;
6 is a view showing a light emitting device according to the embodiment;
7 is a partially enlarged cross-sectional view of a light emitting device according to the embodiment;
8 is an energy band diagram of a light emitting device according to an embodiment;
9 is a perspective view of a light emitting device package including a light emitting device according to the embodiment;
10 is a cross-sectional view of a light emitting device package including a light emitting device according to the embodiment;
11 is a cross-sectional view of a light emitting device package including a light emitting device according to the embodiment;
12 is a perspective view of a lighting system including a light emitting device according to the embodiment;
FIG. 13 is a sectional view taken along line C-C 'of the lighting system of FIG. 12;
14 is an exploded perspective view of a liquid crystal display device including a light emitting device according to the embodiment;
15 is an exploded perspective view of a liquid crystal display including the light emitting device according to the embodiment.

In the description of embodiments, each layer, region, pattern, or structure is “under” a substrate, each layer (film), region, pad, or “on” of a pattern or other structure. In the case of being described as being formed on the upper or lower, the "on", "under", upper, and lower are "direct" "directly" or "indirectly" through other layers or structures.

In addition, the description of the positional relationship between each layer or structure, please refer to this specification, or drawings attached to this specification.

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 and area of each component do not entirely reflect actual size or area.

Referring to FIG. 1, the light emitting device 100 may include a substrate 110 and a light emitting structure 160 disposed on the substrate 110. The light emitting structure 160 may include a first semiconductor layer 120, The active layer 130, the intermediate layer 140, and the second semiconductor layer 150 may be included.

The substrate 110 may be formed of a material having a light transmitting property, for example, any one of sapphire (Al ₂ O ₃ ), GaN, ZnO, AlO, but is not limited thereto. In addition, the SiC substrate may be more thermally conductive than the sapphire (Al ₂ O ₃ ) substrate. However, the refractive index of the substrate 110 may be smaller than the refractive index of the first semiconductor layer 120 for light extraction efficiency.

Meanwhile, a PSS (Patterned SubStrate) structure may be provided on the substrate 110 to increase light extraction efficiency. The substrate 110 referred to herein may or may not have a PSS structure.

Meanwhile, a buffer layer (not shown) may be disposed on the substrate 110 to mitigate lattice mismatch between the substrate 110 and the first semiconductor layer 120 and to easily grow the semiconductor layer. The buffer layer (not shown) may be formed in a low temperature atmosphere, and may be formed of a material capable of alleviating the difference in lattice constant between the semiconductor layer and the substrate. For example, materials such as GaN, InN, AlN, AlInN, InGaN, AlGaN, and InAlGaN can be selected and not limited thereto.

A light emitting structure 160 including a first semiconductor layer 120, an active layer 130, and a second semiconductor layer 150 may be formed on a buffer layer (not shown).

The first semiconductor layer 120 may be located on a buffer layer (not shown). The first semiconductor layer 120 may be formed of an n-type semiconductor layer and may provide electrons to the active layer 130. The first semiconductor layer 120 is, for _{example, In x Al y Ga 1 -x-} y N (0 = x = 1, 0 = y = 1, 0 = x + y = 1) semiconductor material having a compositional formula of For example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc. may be selected, and n-type dopants such as Si, Ge, Sn, and the like may be doped.

Further, the semiconductor layer 120 may further include an undoped semiconductor layer (not shown), but the present invention is not limited thereto. The un-doped semiconductor layer is a layer formed for improving the crystallinity of the first semiconductor layer 120 and has a lower electrical conductivity than the first semiconductor layer 120 without doping the n-type dopant. May be the same as the semiconductor layer 120.

The active layer 130 may be formed on the first semiconductor layer 120. The active layer 130 may be formed of a single or multiple quantum well structure, a quantum-wire structure, a quantum dot structure, or the like using a compound semiconductor material of Group 3-V group elements.

If the active layer 130 is formed of a quantum well structure, for example, the well having a composition formula of _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0 ≤y≤1, 0≤x + y≤1) It may have a single or multiple quantum well structure having a layer and a barrier layer having a composition formula of In _a Al _b Ga ₁ _-a- _b N (0≤a≤1, 0≤b≤1, 0≤a + b≤1). Can be. The well layer may be formed of a material having a band gap smaller than the band gap of the barrier layer.

In addition, when the active layer 130 has a multi-quantum well structure, each well layer (or not shown), or a barrier layer (not shown) may have different compositions and different band gaps, which are described with reference to FIGS. It will be described later with reference to FIG.

A conductive clad layer (not shown) may be formed on and / or below the active layer 130. The conductive clad layer (not shown) may be formed of an AlGaN-based semiconductor and may have a band gap larger than that of the active layer 130.

The second semiconductor layer 150 may be implemented as a p-type semiconductor layer to inject holes into the active layer 124. A second semiconductor layer 150 is, for example, semiconductor material having a compositional formula of _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) For example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc. may be selected, and p-type dopants such as Mg, Zn, Ca, Sr, and Ba may be doped.

Meanwhile, the intermediate layer 140 may be formed between the active layer 130 and the second semiconductor layer 150, and the intermediate layer 140 is injected from the first semiconductor layer 120 into the active layer 130 when a high current is applied. The electron may be an electron blocking layer that prevents electrons from recombining in the active layer 130 and flows into the second semiconductor layer 150. The intermediate layer 140 has a band gap relatively larger than that of the active layer 130, whereby electrons injected from the first semiconductor layer 130 are injected into the second semiconductor layer 150 without being recombined in the active layer 130. Can be prevented. Accordingly, it is possible to increase the probability of recombination of electrons and holes in the active layer 140 and to prevent a leakage current.

On the other hand, the above-described intermediate layer 140 may have a bandgap larger than the bandgap of the barrier layer included in the active layer 130, for example, may be formed of a semiconductor layer containing Al, such as p-type AlGaN, It is not limited to this.

The first semiconductor layer 120, the active layer 130, the intermediate layer 140, and the second semiconductor layer 150 may be, for example, metal organic chemical vapor deposition (MOCVD) or chemical vapor deposition (MOCVD). Chemical Vapor Deposition (CVD), Plasma-Enhanced Chemical Vapor Deposition (PECVD), Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), Sputtering It may be formed using a method such as, but is not limited thereto.

In addition, the doping concentrations of the conductive dopants in the first semiconductor layer 120 and the second semiconductor layer 150 can be uniformly or nonuniformly formed. That is, the plurality of semiconductor layers may be formed to have various doping concentration distributions, but the invention is not limited thereto.

In addition, the first semiconductor layer 120 may be implemented as an n-type semiconductor layer, the second semiconductor layer 150 may be implemented as a p-type semiconductor layer, and the n-type or p-type semiconductor is formed on the second semiconductor layer 150. A third semiconductor layer (not shown) including a layer may be formed. Accordingly, the light emitting device 100 may have at least one of np, pn, npn, and pnp junction structures.

A part of the first semiconductor layer 120 may be exposed and the first electrode 174 may be formed on the exposed first semiconductor layer 120. In this case, Can be formed. That is, the first semiconductor layer 120 includes an upper surface facing the active layer 130 and a lower surface facing the substrate 110, and the upper surface includes an area at least one region is exposed, and the first electrode 174 is an upper surface. Can be placed on the exposed area of the.

Meanwhile, a method of exposing a part of the first semiconductor layer 120 may use a predetermined etching method, but is not limited thereto. The etching method may be a wet etching method or a dry etching method.

Also, a second electrode 172 may be formed on the second semiconductor layer 150.

Meanwhile, the first and second electrodes 172 and 174 may be conductive materials such as In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W It may include a metal selected from Ti, Ag, Cr, Mo, Nb, Al, Ni, Cu, and WTi, or may include an alloy thereof, may be formed in a single layer or multiple layers, but is not limited thereto. .

FIG. 2 is an enlarged cross-sectional view of a region A of FIG. 1.

2, the active layer 130 of the light emitting device 100 may have a multiple quantum well structure, and thus the active layer 130 may include first to third well layers Q1, Q2, and Q3, And a third barrier layer (B1, B2, B3).

According to an embodiment, the first to third well layers Q1, Q2 and Q3 and the first to third barrier layers B1, B2 and B3 may have a structure in which they are alternately stacked as shown in FIG. 2. Can be.

2, the first through third well layers Q1, Q2 and Q3 and the first through third barrier layers B1, B2 and B3 are formed and the first through third barrier layers B1 and B2 Q2 and Q3 and the barrier layers B1, B2 and Q3 and the first through third well layers Q1, Q2 and Q3 are alternately stacked, B3 may be formed to have any number, and the arrangement may also have any arrangement. In addition, as described above, the composition ratios, band gaps, and thicknesses of the materials forming the respective well layers Q1, Q2, and Q3, and the respective barrier layers B1, B2, and B3 may be different from each other. It is not limited as shown in 2.

In addition, according to an embodiment, the third barrier layer B3 formed adjacent to the second semiconductor layer 150 may have a thickness d1, the second barrier layer B2 may have a thickness d2, and d1 may be greater than d2. It can have a large value.

Meanwhile, the third barrier layer B3 may include a first layer 131 and a second layer 132 disposed between the first layer 131 and the intermediate layer 140.

The first layer 131 and the second layer 132 may have different growth conditions, thicknesses, or compositions, but are not limited thereto. For example, the second layer 132 may have more In content than the first layer 131 and less than the well layer.

On the other hand, the second layer 132 may be doped with a p-type dopant such as Mg. As the second layer 132 is doped with a P-type dopant, the hole injection efficiency may be increased and the operating voltage may be lowered.

On the other hand, the second layer 132 may have a predetermined thickness d3 to increase the probability of trapping holes, for example, may have a thickness of 2 nm to 15 nm.

In addition, the first layer 131 and the second layer 132 may be formed to have a different band gap, which will be described later with reference to FIG. 3.

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

Referring to FIG. 3, the band gaps of the first layer 131 and the second layer 132 of the third barrier layer B3 may have different sizes. For example, the band gaps of the second layer 132 may be different from each other. A cart structure formed smaller than the band gap of the first layer 131 may be formed. In addition, the band gap of the second layer 132 is smaller than the band gap of the first layer 131 of the first and second barrier layers B1 and B2, and the third barrier layer B3, and the well layer Q1, It may be formed larger than the band gap of Q2, Q3).

On the other hand, if the thickness of the well layers Q1, Q2, and Q3 serving as the light emitting layer is increased, the probability of trapping the carrier may increase, but if the well layers Q1, Q2, and Q3 are formed thick, piezoelectric polariziton Distortion of the quantum well structure is increased, resulting in low internal quantum efficiency and red shift of the emission spectrum in light emitting devices that generate light by recombination of electrons and holes. The electrical and optical properties of may deteriorate.

The light emitting device 100 according to the embodiment has a cart structure in which one region of the barrier layers B1, B2, and B3, which does not function as a light emitting layer, has a bandgap smaller than that of other regions, and has a cart structure that contributes to trapping carriers. The carrier injection efficiency can be increased without causing spectral defects of the light generated in the well layers Q1, Q2, and Q3 and warpage of the band. Therefore, the injection efficiency of the carrier may be increased and the probability of recombination between holes and electrons may be increased, thereby improving luminous efficiency of the light emitting device 100.

On the other hand, since holes have a smaller mobility than electrons, electrons are excessively injected compared to holes, and electrons are excessively overflowed, and electrons flow over the active layer 130 to the second semiconductor layer 150. Symptoms may occur.

In the light emitting device 100 according to the embodiment, the third barrier layer B3 adjacent to the second semiconductor layer 150 doped with a P-type dopant is formed to have a cart structure, and thus is provided from the second semiconductor layer 150. The probability of trapping of a carrier, for example, a hole, may increase. Therefore, the probability of recombination between the electrons and the holes may be increased, and an overflow from the electrons provided from the first semiconductor layer 120 may be prevented from flowing to the second semiconductor layer 150. The luminous efficiency of 100 may be improved.

4 is a view comparing the light intensity of the light emitting device according to the prior art and the light emitting device according to the embodiment

Referring to FIG. 4, the light emitting device A according to the embodiment includes a barrier layer having a cart structure as described above, and the hole injection efficiency and the recombination probability of holes and electrons are increased, thereby increasing the light emitting device according to the prior art. It can be seen that the brightness is improved compared to B).

5 is a view comparing the operating voltage of the light emitting device according to the prior art and the light emitting device according to the embodiment.

Referring to FIG. 5, the light emitting device A according to the embodiment includes a barrier layer having a cart structure as described above, and the barrier layer having the cart structure is doped with a dopant such as Mg to emit light according to the prior art. It can be seen that the operating voltage is lower than that of the device (B).

6 is a view showing a light emitting device according to the embodiment.

Referring to FIG. 6, the light emitting device 200 according to the embodiment may include a substrate 210, a first electrode layer 220, a first semiconductor layer 230, an active layer 250, and a substrate 210 disposed on the substrate 210. The light emitting structure 270 including the second semiconductor layer 260 and the second electrode layer 282 may be included.

The substrate 210 may be formed using a material having excellent thermal conductivity, and may also be formed of a conductive material, and may be formed using a metal material or a conductive ceramic. The substrate 210 may be formed of a single layer and may be formed of a dual structure or multiple structures.

That is, the substrate 210 may be formed of any one selected from a metal, for example, Au, Ni, W, Mo, Cu, Al, Ta, Ag, Pt, or Cr, or may be formed of two or more alloys. It can be formed by stacking materials. In addition, the substrate 210 may be formed of Si, Ge, GaAs, ZnO, SiC, SiGe, GaN, Ga ₂ O ₃ It may be implemented as a carrier wafer such as.

The substrate 210 may facilitate the emission of heat generated from the light emitting device 200, thereby improving thermal stability of the light emitting device 200.

The first electrode layer 220 may be formed on the substrate 210, and the first electrode layer 220 may be an ohmic layer (not shown), a reflective layer (not shown), or a bonding layer (not shown). At least one layer of a bonding layer (not shown) may be included. For example, the first electrode layer 220 may be a structure of an ohmic layer / a reflection layer / a bonding layer, a laminate structure of an ohmic layer / a reflection layer, or a structure of a reflection layer (including an ohmic layer) / a bonding layer. For example, the first electrode layer 220 may be formed by sequentially stacking a reflective layer and an ohmic layer on an insulating layer.

The reflective layer (not shown) may be disposed between the ohmic layer (not shown) and the insulating layer (not shown), and have excellent reflective properties such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg , Zn, Pt, Au, Hf, or a combination of these materials, or a combination of these materials or IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, to form a multi-layer using a transparent conductive material such as Can be. Further, the reflective layer (not shown) can be laminated with IZO / Ni, AZO / Ag, IZO / Ag / Ni, AZO / Ag / Ni and the like. In addition, when the reflective layer (not shown) is formed of a material in ohmic contact with the light emitting structure 270 (eg, the first semiconductor layer 230), the ohmic layer (not shown) may not be formed separately, and the present invention is not limited thereto. I do not.

The ohmic layer (not shown) is in ohmic contact with the bottom surface of the light emitting structure 270, and may be formed in a layer or a plurality of patterns. The ohmic layer (not shown) may be formed of a transparent electrode layer and a metal. For example, ITO (indium tin oxide), IZO (indium zinc oxide), IZTO (indium zinc tin oxide) ), IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IrO _x , RuO _x , RuO _x / Ni, Ag, Ni / IrO _x / Au, and Ni / IrO _x / Au / ITO. The ohmic layer (not shown) is for smoothly injecting a carrier into the first semiconductor layer 230 and is not necessarily formed.

The first electrode layer 220 may include a bonding layer (not shown), and the bonding layer may include a barrier metal or a bonding metal such as Ti, Au, Sn, Ni , Cr, Ga, In, Bi, Cu, Ag, or Ta.

The light emitting structure 270 may include at least a first semiconductor layer 230, an active layer 250 and a second semiconductor layer 260 and may be formed between the first semiconductor layer 230 and the second semiconductor layer 260 And the active layer 250 may be disposed.

The first semiconductor layer 230 may be formed on the first electrode layer 220. The first semiconductor layer 230 may be implemented as a p-type semiconductor layer doped with a p-type dopant. The p-type semiconductor layer contains a semiconductor material, for example, having a compositional formula of _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0 ≤y≤1, 0≤x + y≤1) GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN and the like may be selected, and p-type dopants such as Mg, Zn, Ca, Sr, and Ba may be doped.

The active layer 250 may be formed on the first semiconductor layer 230. The active layer 250 may be formed of a single or multiple quantum well structure, a quantum-wire structure, a quantum dot structure, or the like using a compound semiconductor material of Group 3-V group elements.

Well active layer 250 has a composition formula in this case formed of a quantum well structure, for _{example, In x Al y Ga 1 -x-} y N (0≤x≤1, 0 ≤y≤1, 0≤x + y≤1) It can have a single or quantum well structure having a layer and a barrier layer having a composition formula of In _a Al _b Ga ₁ _-a- _b N (0≤a≤1, 0≤b≤1, 0≤a + b≤1). have. The well layer may be formed of a material having a band gap smaller than the band gap of the barrier layer.

A conductive clad layer (not shown) may be formed on and / or below the active layer 250. The conductive clad layer (not shown) may be formed of an AlGaN-based semiconductor and may have a band gap larger than that of the active layer 250.

In addition, when the active layer 250 has a multi-quantum well structure, each well layer (or not shown), or a barrier layer (not shown) may have different compositions and different band gaps, which are described with reference to FIGS. 7 to 7. It will be described later with reference to FIG.

Meanwhile, an intermediate layer 240 may be formed between the active layer 250 and the first semiconductor layer 230, and the intermediate layer 240 is injected from the second semiconductor layer 260 into the active layer 250 when a high current is applied. It may be an electron blocking layer that prevents electrons from flowing into the first semiconductor layer 230 without recombination in the active layer 250. Electrons injected from the second semiconductor layer 260 are injected into the first semiconductor layer 230 without recombination in the active layer 250 because the intermediate layer has a band gap relatively larger than that of the active layer 250 The phenomenon can be prevented. Accordingly, the probability of recombination of electrons and holes in the active layer 250 can be increased and leakage current can be prevented.

Meanwhile, the above-described intermediate layer 240 may have a bandgap larger than the bandgap of the barrier layer included in the active layer 250, and may be formed of a semiconductor layer including Al, such as p-type AlGaN, but is not limited thereto. .

A second semiconductor layer 260 may be formed on the active layer 250. The second semiconductor layer 260 may be implemented as an n-type semiconductor layer, and the n-type semiconductor layer may be, for example, In _x Al _y Ga ₁ _-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x A semiconductor material having a composition of + y≤≤≤≤ can be selected from, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, and the like, for example, n such as Si, Ge, Sn, Se, Te Type dopants may be doped.

A second electrode layer 282 electrically connected to the second semiconductor layer 260 may be formed on the second semiconductor layer 260. The second electrode layer 282 may include at least one pad or / . &Lt; / RTI > The second electrode layer 282 may be disposed in the center region, the outer region, or the edge region of the upper surface of the second semiconductor layer 260, but the present invention is not limited thereto. The second electrode layer 282 may be disposed in a region other than the upper portion of the second semiconductor layer 260, but the present invention is not limited thereto.

The second electrode layer 282 is a conductive material, for example In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr It may be formed in a single layer or multiple layers using a metal or an alloy selected from among Mo, Nb, Al, Ni, Cu, and WTi.

Meanwhile, the light emitting structure 270 may include a third semiconductor layer (not shown) having a polarity opposite to that of the second semiconductor layer 260 on the second semiconductor layer 260. Also, the first semiconductor layer 230 may be an n-type semiconductor layer, and the second semiconductor layer 260 may be a p-type semiconductor layer. Accordingly, the light emitting structure layer 270 may include at least one of an N-P junction, a P-N junction, an N-P-N junction, and a P-N-P junction structure.

A light extracting structure 284 may be formed on the upper portion of the light emitting structure 270.

The light extracting structure 270 may be formed on the upper surface of the second semiconductor layer 260 or may be formed on a light transmitting electrode layer (not shown) after a light transmitting electrode layer (not shown) is formed on the light emitting structure 270 But not limited to,

The light extracting structure 284 may be formed in a light transmitting electrode layer (not shown), or in a part or all of the upper surface of the second semiconductor layer 260. The light extracting structure 284 may be formed by performing etching on at least one region of the light transmitting electrode layer (not shown) or the upper surface of the second semiconductor layer 260, but is not limited thereto. The etching process includes a wet etching process and / or a dry etching process. As the etching process is performed, the upper surface of the light transmitting electrode layer (not shown) or the upper surface of the second semiconductor layer 260 forms the light extracting structure 284 And may include roughness. The roughness may be irregularly formed in a random size, but is not limited thereto. The roughness may be at least one of a texture pattern, a concave-convex pattern, and an uneven pattern, which is an uneven surface.

The roughness may be formed to have various shapes such as a cylinder, a polygonal column, a cone, a polygonal pyramid, a truncated cone, a polygonal pyramid, and the like, preferably including a horn shape.

Meanwhile, the light extracting structure 284 may be formed by a photoelectrochemical (PEC) method or the like, but is not limited thereto. Light generated from the active layer 250 may be transmitted through a light-transmitting electrode layer (not shown) or a second semiconductor layer (not shown) as the light extracting structure 284 is formed on the upper surface of the light- Can be prevented from being totally reflected and reabsorbed or scattered from the upper surface of the light emitting device 260, thereby contributing to improvement of light extraction efficiency of the light emitting device 200.

Passivation (not shown) may be formed on side and upper regions of the light emitting structure 270, and passivation (not shown) may be formed of an insulating material.

FIG. 7 is an enlarged cross-sectional view of a region B of FIG. 6.

Referring to FIG. 7, the active layer 250 of the light emitting device 200 may have a multi-quantum well structure, and thus the active layer 250 may include the first to third well layers Q1, Q2, and Q3 and the first to third wells. It may include a third barrier layer (B1, B2, B3).

According to an embodiment, the first to third well layers Q1, Q2 and Q3 and the first to third barrier layers B1, B2 and B3 may have a structure in which they are alternately stacked as shown in FIG. 7. Can be.

Meanwhile, in FIG. 7, the first to third well layers Q1, Q2, and Q3 and the first to third barrier layers B1, B2, B3, are formed, respectively, and the first to third barrier layers B1 and B2, respectively. , B3) and the first to third well layers Q1, Q2, and Q3 are alternately stacked, but are not limited thereto, and the well layers Q1, Q2, Q3, and barrier layers B1, B2, B3) may be formed to have any number, and the arrangement may also have any arrangement. In addition, as described above, the composition ratios, band gaps, and thicknesses of the materials forming the respective well layers Q1, Q2, and Q3, and the respective barrier layers B1, B2, and B3 may be different from each other. It is not limited as shown in 2.

Further, according to the embodiment, the third barrier layer B3 formed adjacent to the first semiconductor layer 230 doped with the p-type dopant has a thickness d1 and the first and second barrier layers B1 and B2. May have a thickness d2 and d1 may have a value greater than d2.

The third barrier layer B3 may include a first layer 151 and a second layer 252 disposed between the first layer 251 and the intermediate layer 240.

The first layer 251 and the second layer 252 may have different growth conditions, thicknesses, or compositions, but are not limited thereto. For example, the second layer 252 may have more In content than the first layer 251 and less than the well layer.

Meanwhile, the second layer 252 may be doped with a p-type dopant such as Mg. As the second layer 252 is doped with a P-type dopant, hole injection efficiency may be improved and an operating voltage may be lowered.

On the other hand, the second layer 252 may have a predetermined thickness d3 to increase the probability of trapping holes, for example, may have a thickness of 2 nm to 15 nm.

In addition, the first layer 251 and the second layer 252 may be formed to have a different band gap, which will be described later with reference to FIG. 8.

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

Referring to FIG. 8, the band gaps of the first layer 251 and the second layer 252 of the third barrier layer B3 may have different sizes, for example, the band gap of the second layer 252 may be It may be formed smaller than the band gap of the first layer 251 to form a cart (cart) structure. In addition, the bandgap of the second layer 252 is smaller than the bandgap of the first and second barrier layers B1 and B2 and the bandgap of the first layer 251 of the third barrier layer B3. It may be formed larger than the band gap of (Q1, Q2, Q3).

The light emitting device according to the embodiment has a cart structure in which one region of the barrier layers B1, B2, and B3, which does not function as a light emitting layer, has a bandgap smaller than that of the other region, and has a cart structure that contributes to trapping the carrier. Carrier injection efficiency can be increased without causing spectral defects of the light generated at (Q1, Q2, Q3) and warpage of the band. Therefore, the injection efficiency of the carrier is increased and the probability of recombination between holes and electrons is increased, so that the luminous efficiency of the light emitting device can be improved.

On the other hand, since holes have a smaller mobility than electrons, electrons are excessively injected compared to holes, and an electron overflow phenomenon, and an electron flowing over the active layer 240 to the second semiconductor layer 260 may occur. .

In addition, since the third barrier layer B3 adjacent to the first semiconductor layer 230 doped with the P-type dopant is formed to have a cart structure, the probability of trapping carriers, for example, holes, provided from the first semiconductor layer 230 is increased. Can increase. Accordingly, the probability of recombination between the electrons and the holes may be increased, and the overflow of the electrons provided from the first semiconductor layer 230 to the second semiconductor layer 260 may be prevented. The luminous efficiency of 200 may be improved.

9 to 11 are a perspective view and a cross-sectional view showing a light emitting device package according to the embodiment.

9 to 11, the light emitting device package 300 includes a body 310 having a cavity 320, first and second lead frames 340 and 350 mounted on the body 310, and a first And a light emitting device 330 electrically connected to the second lead frames 340 and 350, and an encapsulant (not shown) filled in the cavity 320 to cover the light emitting device 330.

The body 310 is made of a resin material such as polyphthalamide (PPA), silicon (Si), aluminum (Al), aluminum nitride (AlN), photosensitive glass (PSG), polyamide 9T (PA9T) ), Neo geotactic polystyrene (SPS), a metal material, sapphire (Al ₂ O ₃ ), beryllium oxide (BeO), may be formed of at least one of a printed circuit board (PCB, Printed Circuit Board). The body 310 may be formed by injection molding, etching, or the like, but is not limited thereto.

The inner surface of the body 310 may be formed inclined surface. The angle of reflection of the light emitted from the light emitting device 330 may vary according to the angle of the inclined surface, and thus the directivity of the light emitted to the outside may be adjusted.

As the direction angle of light decreases, the concentration of light emitted from the light emitting device 330 to the outside increases. On the contrary, as the direction angle of light increases, the concentration of light emitted to the outside from the light emitting device 330 decreases.

On the other hand, the shape viewed from above the cavity 320 formed in the body 310 may be a shape of a circle, a square, a polygon, an oval, and the like, may be a curved shape of the corner, but is not limited thereto.

The light emitting device 330 is mounted on the first lead frame 340 and may be, for example, a light emitting device emitting light of red, green, blue, white, or UV (ultra violet) light emitting device emitting ultraviolet light. But it is not limited thereto. In addition, one or more light emitting devices 330 may be mounted.

In addition, the light emitting device 330 may be a horizontal type in which all of its electrical terminals are formed on the upper surface, or a vertical type or flip chip formed on the upper and lower surfaces. Applicable

On the other hand, the light emitting device 330 according to the embodiment has an electrode (not shown) extending to the side of the light emitting device (not shown), the operation voltage is improved and the luminous efficiency is improved, so that the brightness of the light emitting device package 300 Can be improved.

The encapsulant (not shown) may be filled in the cavity 320 to cover the light emitting device 330.

The encapsulant (not shown) may be formed of silicon, epoxy, and other resin materials, and may be formed by filling in the cavity 320 and then UV or heat curing the same.

In addition, the encapsulant (not shown) may include a phosphor, and the phosphor may be selected from a wavelength of light emitted from the light emitting device 330 to allow the light emitting device package 300 to realize white light.

The phosphor is one of a blue light emitting phosphor, a blue green light emitting phosphor, a green light emitting phosphor, a yellow green light emitting phosphor, a yellow light emitting phosphor, a yellow red light emitting phosphor, an orange light emitting phosphor, and a red light emitting phosphor according to the wavelength of light emitted from the light emitting element 330. Can be applied.

That is, the phosphor may be excited by the light having the first light emitted from the light emitting device 330 to generate the second light. For example, when the light emitting element 330 is a blue light emitting diode and the phosphor is a yellow phosphor, the yellow phosphor may be excited by blue light to emit yellow light, and the blue light and blue light generated by the blue light emitting diode As the generated yellow light is mixed, the light emitting device package 300 may provide white light.

Similarly, when the light emitting device 330 is a green light emitting diode, a magenta phosphor or a mixture of blue and red phosphors is mixed. When the light emitting device 330 is a red light emitting diode, a cyan phosphor or a blue and green phosphor is used. For example,

Such a fluorescent material may be a known fluorescent material such as a YAG, TAG, sulfide, silicate, aluminate, nitride, carbide, nitridosilicate, borate, fluoride or phosphate.

The first and second lead frames 340 and 350 may be formed of a metal material, for example, titanium (Ti), copper (Cu), nickel (Ni), gold (Au), chromium (Cr), and tantalum (Ta). , Platinum (Pt), tin (Sn), silver (Ag), phosphorus (P), aluminum (Al), indium (In), palladium (Pd), cobalt (Co), silicon (Si), germanium (Ge) It may include one or more materials or alloys of hafnium (Hf), ruthenium (Ru), iron (Fe). In addition, the first and second lead frames 340 and 350 may be formed to have a single layer or a multilayer structure, but are not limited thereto.

The first second lead frames 340 and 350 are spaced apart from each other and electrically separated from each other. The light emitting device 330 is mounted on the first and second lead frames 340 and 350, and the first and second lead frames 340 and 350 are in direct contact with the light emitting device 330 or a soldering member (not shown). May be electrically connected through a material having conductivity such as C). In addition, the light emitting device 330 may be electrically connected to the first and second lead frames 340 and 350 through wire bonding, but is not limited thereto. Therefore, when power is connected to the first and second lead frames 340 and 350, power may be applied to the light emitting device 330. Meanwhile, several lead frames (not shown) may be mounted in the body 310 and each lead frame (not shown) may be electrically connected to the light emitting device 330, but is not limited thereto.

Meanwhile, referring to FIG. 11, the light emitting device package 300 according to the embodiment may include an optical sheet 380, and the optical sheet 380 may include a base portion 382 and a prism pattern 384. Can be.

The base portion 382 is a support for forming the prism pattern 384 and is made of a transparent material having excellent thermal stability. For example, the base portion 382 is made of polyethylene terephthalate, polycarbonate, polypropylene, polyethylene, polystyrene, and polyepoxy. It may be made of any one selected from the group, but is not limited thereto.

In addition, the base 382 may include a phosphor (not shown). As an example, the base part 382 may be formed by curing the phosphor (not shown) evenly in a state in which the base part 382 is evenly dispersed. As such, when the base portion 382 is formed, the phosphor (not shown) may be uniformly distributed over the entire base portion 382.

On the other hand, a three-dimensional prism pattern 384 may be formed on the base portion 382 for refracting and condensing light. The material constituting the prism pattern 384 may be acrylic resin, but is not limited thereto.

The prism pattern 384 includes a plurality of linear prisms arranged in parallel with one another in one direction on one surface of the base portion 382, and a vertical cross section of the linear prism in the axial direction may be a triangle.

Since the prism pattern 384 has the effect of condensing light, when the optical sheet 380 is attached to the light emitting device package 300 of FIG. 6C, the linearity of the light is improved, and the brightness of the light of the light emitting device package 300 is increased. Can be improved.

On the other hand, the prism pattern 384 may include a phosphor (not shown).

The phosphor (not shown) is uniformly formed in the prism pattern 384 by forming the prism pattern 384 in a dispersed state, for example, by mixing with an acrylic resin to form a paste or slurry, and then forming the prism pattern 384. Can be included.

When the phosphor (not shown) is included in the prism pattern 384 as described above, the uniformity and distribution of the light of the light emitting device package 300 are improved, and in addition to the light condensing effect of the prism pattern 384, the phosphor is not shown. Due to the light scattering effect, the directivity of the light emitting device package 300 can be improved.

A plurality of light emitting device packages 300 according to the embodiment may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, or the like, which is an optical member, may be disposed on an optical path of the light emitting device package 300. Such a light emitting device package, a substrate, and an optical member can function as a light unit. Another embodiment may be implemented as a display device, an indicator device, or a lighting system including the light emitting device or the light emitting device package described in the above embodiments, and for example, the lighting system may include a lamp or a street lamp.

12 is a perspective view illustrating a lighting apparatus including a light emitting device package according to an embodiment, and FIG. 13 is a cross-sectional view illustrating a C-C 'cross section of the lighting apparatus of FIG. 12.

12 and 13, the lighting device 400 may include a body 410, a cover 430 fastened to the body 410, and a closing cap 450 positioned at both ends of the body 410. have.

The light emitting device module 440 is fastened to the lower surface of the body 410, and the body 410 is conductive so that heat generated from the light emitting device package 444 can be discharged to the outside through the upper surface of the body 410. And it may be formed of a metal material having an excellent heat dissipation effect.

The light emitting device package 444 may be mounted on the PCB 442 in multiple colors and in multiple rows to form an array. The light emitting device package 444 may be mounted at the same interval or may be mounted with various separation distances as necessary to adjust brightness. As the PCB 442, a metal core PCB (MPPCB) or a PCB made of FR4 may be used.

In particular, the light emitting device package 444 includes a light emitting device (not shown), while the light emitting device (not shown) according to the embodiment has an electrode (not shown) extending to the side of the light emitting device (not shown), As the operating voltage is improved and the luminous efficiency is improved, the luminous intensity of the light emitting device package 444 and the lighting device 400 may be improved.

The cover 430 may be formed in a circular shape to surround the lower surface of the body 410, but is not limited thereto.

The cover 430 protects the light emitting device module 440 from the outside and the like. In addition, the cover 430 may include diffusing particles to prevent glare of the light generated from the light emitting device package 444 and to uniformly emit light to the outside, and may also include at least one of an inner surface and an outer surface of the cover 430. A prism pattern or the like may be formed on either side. In addition, a phosphor may be applied to at least one of an inner surface and an outer surface of the cover 430.

On the other hand, since the light generated from the light emitting device package 444 is emitted to the outside through the cover 430, the cover 430 should have excellent light transmittance, and has sufficient heat resistance to withstand the heat generated from the light emitting device package 444. The cover 430 is preferably formed of a material including polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), or the like. .

Closing cap 450 is located at both ends of the body 410 may be used for sealing the power supply (not shown). In addition, the fin 450 is formed on the finishing cap 450, so that the lighting device 400 according to the embodiment can be used immediately without a separate device on the terminal from which the conventional fluorescent lamp is removed.

14 is an exploded perspective view of a liquid crystal display including the light emitting device according to the embodiment.

FIG. 14 illustrates an edge-light method. The LCD 500 may include a liquid crystal display panel 510 and a backlight unit 570 for providing light to the liquid crystal display panel 510.

The liquid crystal display panel 510 may display an image by using light provided from the backlight unit 570. The liquid crystal display panel 510 may include a color filter substrate 512 and a thin film transistor substrate 514 facing each other with a liquid crystal interposed therebetween.

The color filter substrate 512 may implement colors of an image displayed through the liquid crystal display panel 510.

The thin film transistor substrate 514 is electrically connected to the printed circuit board 518 on which a plurality of circuit components are mounted through the driving film 517. The thin film transistor substrate 514 may apply a driving voltage provided from the printed circuit board 518 to the liquid crystal in response to the driving signal provided from the printed circuit board 518.

The thin film transistor substrate 514 may include a thin film transistor and a pixel electrode formed of a thin film on another substrate of a transparent material such as glass or plastic.

The backlight unit 570 may convert the light provided from the light emitting device module 520, the light emitting device module 520 into a surface light source, and provide the light guide plate 530 to the liquid crystal display panel 510. Reflective sheet for reflecting the light emitted from the rear of the light guide plate 530 and the plurality of films 550, 566, 564 to uniform the luminance distribution of the light provided from the 530 and improve the vertical incidence ( 540.

The light emitting device module 520 may include a PCB substrate 522 so that a plurality of light emitting device packages 524 and a plurality of light emitting device packages 524 may be mounted to form an array.

In particular, the light emitting device package 524 includes a light emitting device (not shown), the light emitting device (not shown) according to the embodiment has an electrode (not shown) extending to the side of the light emitting device (not shown), the operation As the voltage is improved and the luminous efficiency is improved, the luminous intensity of the light emitting device package 524 and the backlight unit 570 may be improved.

Meanwhile, the backlight unit 570 includes a diffusion film 566 for diffusing light incident from the light guide plate 530 toward the liquid crystal display panel 510, and a prism film 550 for condensing the diffused light to improve vertical incidence. ), And may include a protective film 564 to protect the prism film 550.

15 is an exploded perspective view of a liquid crystal display including the light emitting device according to the embodiment. However, the parts shown and described in Fig. 14 are not repeatedly described in detail.

15 is a direct view, the liquid crystal display device 600 may include a liquid crystal display panel 610 and a backlight unit 670 for providing light to the liquid crystal display panel 610.

Since the liquid crystal display panel 610 is the same as that described with reference to FIG. 8, a detailed description thereof will be omitted.

The backlight unit 670 may include a plurality of light emitting device modules 623, a reflective sheet 624, a lower chassis 630 in which the light emitting device modules 623 and the reflective sheet 624 are accommodated, and an upper portion of the light emitting device module 623. It may include a diffusion plate 640 and a plurality of optical film 660 disposed in the.

LED Module 623 A plurality of light emitting device packages 622 and a plurality of light emitting device packages 622 may be mounted to include a PCB substrate 621 to form an array.

In particular, the light emitting device package 622 includes a light emitting device (not shown), the light emitting device (not shown) according to the embodiment has an electrode (not shown) extending to the side of the light emitting device (not shown), the operation As the voltage is improved and the luminous efficiency is improved, the luminous intensity of the light emitting device package 622 and the backlight unit 670 may be improved.

The reflective sheet 624 reflects the light generated from the light emitting device package 622 in the direction in which the liquid crystal display panel 610 is positioned to improve light utilization efficiency.

On the other hand, the light generated from the light emitting device module 623 is incident on the diffusion plate 640, the optical film 660 is disposed on the diffusion plate 640. The optical film 660 may include a diffusion film 666, a prism film 650, and a protective film 664.

Meanwhile, the light emitting device according to the embodiment is not limited to the configuration and method of the embodiments described above, but the embodiments may be modified so that all or some of the embodiments may be selectively And may be configured in combination.

In addition, while the preferred embodiments have been shown and described, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments described above, and the present invention may be used in the art without departing from the gist of the invention as claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

100 light emitting element 120 first semiconductor layer
130: active layer 140: intermediate layer
150: second semiconductor layer 160: light emitting structure
Q1, Q2, Q3: well layer B1, B2, B3: barrier layer
131: first layer 132: second layer

Claims

And a light emitting structure including a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer.
The first semiconductor layer is a P-type semiconductor layer doped with a P-type dopant,
The active layer includes a well layer and a barrier layer alternately stacked,
The barrier layer comprises a first barrier layer and a second barrier layer disposed between the first barrier layer and the first semiconductor layer,
The second barrier layer comprises a first layer and a second layer disposed between the first layer and the first semiconductor layer,
The first layer has a first bandgap, the second layer has a second bandgap,
The second band gap is smaller than the first band gap light emitting device.

The method of claim 1,
The well layer has a third band gap,
The second band gap is larger than the third band gap light emitting device.

The method of claim 1,
The thickness of the second layer,
2 nm to 15 nm light emitting device.

The method of claim 1,
The P-type dopant,
A light emitting device comprising any one of Mg, Zn, Ca, Sr, Ba.

The method of claim 1,
The second layer includes In.

The method of claim 1,
The second layer,
A light emitting device having an In content smaller than the well layer and more than the first layer.

The method of claim 1,
The second layer,
A light emitting device doped with a p-type dopant.

The method of claim 7, wherein
The P-type dopant,
A light emitting device comprising any one of Mg, Zn, Ca, Sr, Ba.

The method of claim 1,
And an intermediate layer disposed between the second layer and the first semiconductor layer.
The intermediate layer is a light emitting device that is an electron blocking layer.

10. The method of claim 9,
Wherein the intermediate layer comprises:
A light emitting device having a band gap larger than the barrier layer.

The method of claim 9.
Wherein the intermediate layer comprises:
Light emitting element including Al.

The method of claim 1,
A second electrode on the first semiconductor layer;
A support substrate under the second semiconductor layer; And
And a portion of the upper surface of the first conductive semiconductor layer is exposed by removing a portion of the second conductive semiconductor layer and the active layer, and a first electrode on the upper surface of the exposed first conductive semiconductor layer.

The method of claim 1,
A support substrate under the first semiconductor layer;
A first electrode between the support substrate and the second conductive semiconductor layer; And
And a second electrode on the second semiconductor layer.

The method of claim 13.
And a concave-convex portion having a predetermined roughness on the second semiconductor layer.