KR20120110831A

KR20120110831A - Light emitting device

Info

Publication number: KR20120110831A
Application number: KR1020110028964A
Authority: KR
Inventors: 나종호; 심세환; 윤재인
Original assignee: 엘지이노텍 주식회사
Priority date: 2011-03-30
Filing date: 2011-03-30
Publication date: 2012-10-10

Abstract

PURPOSE: A light emitting device is provided to improve the coupling ratio of holes and electrons by forming a band gap of a first well layer larger than band gaps of first and second well layers. CONSTITUTION: An active layer(130) includes well layers(Q1,Q2,Q3) and barrier layers(B1,B2,B3). The well layers includes a first well layer and a second well 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. The thickness of the first well layer is 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.

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 formed 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.

The embodiment provides a light emitting device having improved light emission 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 an energy band diagram of a light emitting device according to an embodiment;
5 is a view showing a growth temperature of a light emitting device according to an embodiment with time;
6A is a view showing a change in output of the light emitting device according to the embodiment;
6B is a view illustrating a change in operating voltage of a light emitting device according to an embodiment;
6C is a view illustrating a change in reverse voltage of a light emitting device according to an embodiment;
6D is a view illustrating an optical luminescence spectrum of a light emitting device according to the embodiment;
7 is a view showing a light emitting device according to the embodiment;
8 is a partially enlarged cross-sectional view of a light emitting device according to the embodiment;
9 is a view showing an energy band diagram of a light emitting device according to the embodiment;
10 is a view showing an energy band diagram of a light emitting device according to the embodiment;
11 is a perspective view of a light emitting device package including a light emitting device according to the embodiment;
12 is a cross-sectional view of a light emitting device package including a light emitting device according to the embodiment;
13 is a cross-sectional view of a light emitting device package including a light emitting device according to the embodiment;
14 is a perspective view of a lighting system including a light emitting device according to the embodiment;
15 is a cross-sectional view taken along the line C-C 'of the lighting system of FIG.
16 is an exploded perspective view of a liquid crystal display device including the light emitting device according to the embodiment;
17 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 support member 110 and a light emitting structure 160 disposed on the support member 110, and the light emitting structure 160 may include the first semiconductor layer 120. ), An active layer 130, an intermediate layer 140, and a second semiconductor layer 150.

The supporting member 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 support member may have a higher thermal conductivity than the sapphire (Al ₂ O ₃ ) support member. However, the refractive index of the support member 110 is preferably smaller than the refractive index of the first semiconductor layer 120 for light extraction efficiency.

On the other hand, the upper surface of the support member 110 may be provided with a PSS (Pattern Substrate) structure to increase the light extraction efficiency. The support member 110 referred to herein may or may not have a PSS structure.

A buffer layer (not shown) may be disposed on the support member 110 to mitigate lattice mismatch between the support member 110 and the first semiconductor layer 120 and allow the semiconductor layer to grow easily. 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 support member. For example, materials such as GaN, InN, AlN, AlInN, InGaN, AlGaN, and InAlGaN can be selected and not limited thereto. The buffer layer (not shown) may grow as a single crystal on the support member 110, and the buffer layer (not shown) grown as the single crystal may improve crystallinity of the first semiconductor layer 120 grown on the buffer layer (not shown). You can.

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, 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 n-type dopants such as Si, Ge, Sn, and the like may be doped.

In addition, an undoped semiconductor layer (not shown) may be further included below the first semiconductor layer 120, but embodiments are not limited thereto. The undoped semiconductor layer is a layer formed to improve the crystallinity of the first semiconductor layer 120, except that the n-type dopant is not doped and thus has a lower electrical conductivity than the first semiconductor layer 120. It 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 (not shown) may have different In contents and different band gaps, which will be described later with reference to FIGS. 2 to 4. .

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.

Meanwhile, the above-described intermediate layer 140 may have a bandgap larger than the bandgap of the barrier layer included in the active layer 130, and may be formed of a semiconductor layer including Al, such as p-type AlGaN, but is not limited thereto. .

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.

The first semiconductor layer 120 may be a p-type semiconductor layer, the second semiconductor layer 150 may be an n-type semiconductor layer, and an n-type or p-type semiconductor may be formed on the second semiconductor layer 150. [ A third semiconductor layer (not shown) 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 support member 110, and the upper surface includes an area at least one region is exposed, and the first electrode 174 is It may be disposed on the exposed area of the upper surface.

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 third well layer Q3 formed adjacent to the second semiconductor layer 150 may have a thickness d1, the second well layer Q2 may have a thickness d2, and d1 may be greater than d2. Can have Preferably, d1 may have a thickness of 110% to 150% relative to d2.

The first through third well layers Q1, Q2 and Q3 and the first through third barrier layers B1, B2 and B3 may have a structure in which they are alternately stacked as shown in FIG.

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.

3 to 4 are diagrams showing energy band diagrams of light emitting devices according to embodiments.

3 to 4, the band gap of the third well layer Q3 may be larger than the band gaps of the first and second well layers Q1 and Q2.

The band gap of the third well layer Q3 adjacent to the second semiconductor layer 150 providing holes to the active layer 130 is larger than the band gaps of the first and second well layers Q1 and Q2. Therefore, the movement of holes can be facilitated. Accordingly, holes beyond the second semiconductor layer 150 or the intermediate layer 140 may be more easily injected into the third well layer Q3, thereby further increasing the injection efficiency of the holes. And the efficiency of injecting holes into the second well layers Q1 and Q2.

In addition, since the band gap of the third well layer Q3 is larger than the first and second well layers Q1 and Q2 and smaller than the barrier layers B1, B2 and B3, the barrier layers B1 and B2 having a large band gap are provided. , B3) and the second semiconductor layer 150 and the band gap between the well layers Q1, Q2 and Q3 having a small band gap, to alleviate the generation of interlayer stress, thereby further improving the reliability of the light emitting device 100. Can be.

On the other hand, in as described above, the well layer (Q1, Q2, Q3) is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0 ≤y≤1, 0≤x + y≤1) It may have a composition formula. The higher the In content of the well layers Q1, Q2, and Q3, the smaller the band gap. On the contrary, the smaller the In content of the well layers Q1, Q2, and Q3, the smaller the band gap of the well layers Q1, Q2, and Q3. Can be large.

Meanwhile, the In content of the third well layer Q3 may be 90% to 99% of the In content of the first and second well layers Q1 and Q2. When the In content is less than 90%, the difference in lattice constant between the first and second well layers Q1 and Q2 becomes larger in the band gap of the third well layer Q3, and the crystallinity is lowered. In addition, when In content is 99% or more, there is no big difference with 1st and 2nd well layers Q1 and Q2, and it does not have a big influence on hole injection and hardening improvement. The ratio may be any one of a molar ratio, a volume ratio, and a mass ratio, but is not limited thereto.

On the other hand, the piezoelectric polariziton generated by the stress due to the lattice constant difference and the orientation between the semiconductor layers may occur in the semiconductor layer. The semiconductor material forming the light emitting element has a large value of the piezoelectric coefficient and thus can cause very large polarization even at small strains. The electric field caused by the two polarizations changes the energy band structure of the quantum well structure, thereby distorting the distribution of electrons and holes. This effect is called the quantum confined stark effect (QCSE), which causes low internal quantum efficiency in light emitting devices that generate light by recombination of electrons and holes, and emits light such as red shift in the emission spectrum. It may adversely affect the electrical and optical characteristics of the device.

As it described above, the composition formula of the well layer (Q1, Q2, Q3) is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0 ≤y≤1, 0≤x + y≤1) The barrier layers B1, B2, and B3 may have a composition formula of In _a Al _b Ga ₁ _-a- _b N (0≤a≤1, 0≤b≤1, 0≤a + b≤1). . The lattice constant of InN is larger than GaN, and as the In content included in the well layers Q1, Q2, and Q3 increases, the lattice constant of the well layers Q1, Q2, and Q3 increases, so that the barrier layers B1, B2, and B3 The difference in lattice constant between the well layers Q1, Q2, and Q3 increases, which results in more strain between the layers. Due to this strain, the polarization effect as described above is further increased to strengthen the internal electric field. Accordingly, the band bends according to the electric field, resulting in a pointed triangle potential well, and the shape where electrons or holes are concentrated in the triangle potential well. May occur. Therefore, the recombination rate of electrons and holes may decrease.

According to an embodiment, as the In content of the third well layer Q3 decreases to decrease the lattice constant, the lattice constant difference between the barrier layers B1, B2 and B3 and the third well layer Q3 may decrease. Can be. Therefore, the generation of the above-described triangle potential wells can be reduced, thus the recombination rate of electrons and holes can be increased, and the luminous efficiency of the light emitting device 100 can be improved.

In addition, since the band gap of the third well layer Q3 adjacent to the second semiconductor layer 150 is large and has a high potential barrier, the carrier (for example, hole) provided in the second semiconductor layer 150 is increased. Resistivity can lead to hole diffusion. Through the diffusion of holes, recombination of electrons and holes occurs in a wider range over the area of the active layer 130, thereby improving the bonding ratio between electrons and holes, and thus the luminous efficiency of the light emitting device 100 may be improved. have.

On the other hand, the crystal defects due to the lattice constant difference between the support member 110 and the light emitting structure 160 formed on the support member 110 tends to increase in accordance with the growth direction, so it is most spaced apart from the support member 110. The second semiconductor layer 150 formed at the predetermined position may have the largest crystal defect. Considering the fact that the hole mobility is lower than the electron mobility, the decrease in the hole injection efficiency due to the decrease in the crystallinity of the second semiconductor layer 150 results in the light emission efficiency of the light emitting device 100. Can be lowered.

However, since the band gap of the third well layer Q3 of the active layer 130 is large, as in the embodiment, the propagation of crystal defects can be blocked, so that the crystal defects of the second semiconductor layer 150 can be improved. The light emitting efficiency of the light emitting device 100 may be improved.

In this case, when the third well layer Q3 has a band gap larger than that of the second well layer Q2, the energy of light generated in each well layer is also different as the band gap between the well layers is different. This means that the wavelength of light generated in each well layer is also different. Accordingly, since the third well layer Q3 has a larger band gap than the second well layer Q2, the third well layer Q3 generates light having a larger energy, thereby generating light having a shorter wavelength. Therefore, broadening of the emission spectrum of the light emitting device may be widened in the short wavelength direction, and a shoulder may be formed in the photoluminescence spectrum of the light emitting device 100.

As described above, the third well layer Q3 formed adjacent to the second semiconductor layer 150 may have a thickness d1, the second well layer Q2 may have a thickness d2, and d1 may have a value greater than d2. Can have

The energy level formula of light generated in the well layer is as follows.

At this time, L corresponds to the thicknesses d1 and d2 of the well layer. Therefore, the thicker the well layers Q1, Q2, and Q3, the lower the energy level of light generated in the well layers Q1, Q2, and Q3. When the third well layer Q3 has a larger band gap than the second well layer Q2, the energy levels between the well layers may be different. Therefore, broadening of the emission spectrum of the light emitting device may be increased, and a shoulder may be formed in the photoluminescence spectrum of the light emitting device 100. According to the embodiment, the thickness of the third well layer Q3 is formed to be thicker than the thickness of the second well layer Q2, so that the band gaps between the well layers Q1, Q2, and Q3 are different from each other. The energy level of light generated in Q2 and Q3) may be uniform, and thus, the broadening of the emission spectrum of the light emitting device 100 may be reduced, and the occurrence of shoulders in the optical luminescence spectrum may be reduced. Therefore, a good well structure is formed, the light emitting efficiency of the light emitting device 100 is improved, and shifting to a short wavelength may not occur.

On the other hand, d1 may have a thickness of 110% to 150% compared to d2.

If d1 is not greater than 110% larger than d2, the decrease in energy of light generated in the third well layer Q3 is small, and thus a short wavelength shift still exists, and if it is larger than 150%, it occurs in the third well layer Q3. There is a possibility that the light energy is too small, causing a long wavelength shift.

On the other hand, as shown in Figure 4, the band gap of the first to third well layer may be formed in large in order, may be formed to have a thick thickness sequentially.

That is, the content of In contained in the first to third quantum well layers Q1, Q2, and Q3 is gradually decreased from the first well layer Q1 to the third well layer Q3, and is sequentially thick. It can be to have.

The holes of the first to third well layers Q1, Q2, and Q3 are formed as the well layers Q1, Q2, and Q3 have larger band gaps as they are adjacent to the second semiconductor layer 150 for injecting holes. Injection efficiency may be improved, and thus, light emission efficiency of the light emitting device 100 may be improved.

In addition, as the band gaps are sequentially increased from the first well layer Q1 to the third well layer Q3, the well layers Q1, Q2, and Q3, the barrier layers B1, B2, and B3, and the first, The difference in lattice constant between the second semiconductor layers 120 and 150 may be alleviated, thereby reducing the occurrence of the triangle potential well, thus increasing the recombination rate of electrons and holes, and improving the luminous efficiency of the light emitting device 100. Can be.

In addition, as described above, the well layers Q1, Q2, and Q3 have a larger band gap, and are formed to have a thicker thickness, so that the energy levels between the well layers Q1, Q2, and Q3 become uniform, thereby making the well layers Q1, Although the band gap between Q2 and Q3) is different, the broadening of the emission spectrum of the light emitting device 100 may be reduced, and the occurrence of shoulders in the optical luminescence spectrum may be reduced. Therefore, a good well structure is formed and the luminous efficiency of the light emitting device 100 can be improved.

5 is a view showing a growth process of a light emitting device according to an embodiment according to growth time and growth temperature.

First, the first semiconductor layer 120 is grown at the growth time t1 at the first growth temperature C1, and then the growth temperature is lowered to the second growth temperature C2 at the growth time t2 to the first semiconductor layer 120 and the active layer 130. A lower auxiliary layer (not shown) may be grown in between. Subsequently, by further lowering the growth temperature, the active layer 130 is grown at the growth time t3 to the growth temperature C3. Thereafter, before the third well layer Q3 is grown during the growth of the active layer 130, the growth temperature may be increased until the growth temperature C4 is reached, thereby growing the third well layer Q3 at the growth temperature C4.

Preferably, C4 may have a value of about 100.4% to 103% relative to C3. In other words, if the growth temperature does not differ by more than 0.4%, it is difficult to adjust the expected crystallinity and the band gap. In addition, when the temperature is higher by 4% or more, the composition of In decreases, making it difficult to obtain a bandgap of a desired wavelength.

As the growth temperature C4 of the third well layer Q3 has a temperature higher than the growth temperature C3 of the first and second well layers Q1 and Q2, the In content of the third well layer Q3 may decrease. Can be. Therefore, as described above, the band gap of the third well layer Q3 may be increased, and the injection efficiency of holes injected into the third well layer Q3 and the second and first well layers Q1 and Q2 may be increased. The light emitting efficiency of the light emitting device may be improved by being increased.

In addition, as the growth temperature C4 of the third well layer Q3 increases, the growth temperature of the first and second semiconductor layers 120 and 150 and the active layer 130 grow at higher temperatures than the active layer 130. The difference between the temperatures can be reduced. Therefore, the thin film characteristics may be improved, thereby improving reliability of the light emitting device.

In addition, the growth time of the third well layer Q3 is longer than the growth time of the first well layer Q1 and the second well layer Q2 so that the third well layer Q3 is the first well layer Q1, And by forming a thicker than the second well layer (Q2), even if the band gap between the well layers (Q1, Q2, Q3), the energy level between the well layers (Q1, Q2, Q3) can be uniform and the light emitting device 100 ), Broadening of the emission spectrum can be reduced, and shoulder generation of the photo luminescence spectrum can be reduced. Therefore, a good well structure is formed and the luminous efficiency of the light emitting device 100 can be improved.

6A is a view showing a change in output of the light emitting device according to the embodiment, FIG. 6B is a view showing a change in operating voltage of the light emitting device according to the embodiment, and FIG. 6C is a reverse voltage of the light emitting device according to the embodiment. voltage). 6D is a diagram illustrating an optical luminescence spectrum of the light emitting device according to the embodiment.

Referring to FIG. 6A, it can be seen that the output of the light emitting device wdT having a large band gap of the well layer adjacent to the p-type semiconductor layer according to the embodiment is improved compared to the comparative example wodT.

Referring to FIG. 6B, it can be seen that the operating voltage of the light emitting device wdT having the large band gap of the well layer adjacent to the p-type semiconductor layer according to the embodiment is substantially the same as the comparative example wodT. Therefore, although the output of the light emitting device is improved, it is not accompanied by an increase in the operating voltage, and as a result, an effect of reducing the operating voltage with the same output can be achieved. It can be confirmed that it can be achieved.

In addition, referring to FIG. 6C, it can be seen that the reverse voltage of the light emitting device wdT in which the band gap of the well layer adjacent to the p-type semiconductor layer is large according to the embodiment is improved compared to the comparative example wodT.

In addition, referring to FIG. 6D, the optical luminescence spectrum of the light emitting device in which the thickness of the well layer adjacent to the p-type semiconductor layer is formed according to the embodiment is represented by a solid line, and the thickness of each well layer is uniform. The photoluminescence spectrum of the device is indicated by the dotted line. In FIG. 6D, the shoulder P is formed in the light luminescence spectrum of the light emitting device in which the band gaps of the well layers are different and the thickness of each well layer is uniform. It can be seen that the optical luminescence spectrum of the light emitting device in which the thickness of the adjacent well layer is thickened has reduced the occurrence of the shoulder and the broadening of the spectrum.

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

Referring to FIG. 7, the light emitting device 200 according to the embodiment includes a support member 210, a first electrode layer 220, a first semiconductor layer 230, and an active layer 250 disposed on the support member 210. And a light emitting structure 270 including a second semiconductor layer 260, and a second electrode layer 282.

The support member 210 may be formed using a material having a high thermal conductivity, or may be formed of a conductive material. The support member 210 may be formed using a metal material or a conductive ceramic. The support member 210 may be formed as a single layer, and may be formed as a double structure or a multiple structure.

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

Such a support member 210 facilitates the release of heat generated in the light emitting device 200, thereby improving the thermal stability of the light emitting device 200.

A first electrode layer 220 may be formed on the support member 210. The first electrode layer 220 may include an ohmic layer (not shown), a reflective layer (not shown) and a bonding layer (not shown). 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 disposed between the first semiconductor layer 230 and the second semiconductor layer 260. The active layer 250 may be formed in the configuration shown.

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.

In addition, when the active layer 250 has a multi-quantum well structure, each well layer (not shown) may have a different In content, a different band gap, and a different thickness, and refer to FIGS. 8 to 10. Will be described later.

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.

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 may be increased, and leakage current may 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 semiconductor material having a compositional formula of + y≤≤), for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, and the like, for example, n, such as Si, Ge, Sn, Se, Te, etc. 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, and the second electrode layer 282 may include at least one pad or an electrode having a predetermined pattern. It may include. The second electrode layer 282 may be disposed in a center region, an outer region, or an edge region of the upper surface of the second semiconductor layer 260, but is not limited thereto. The second electrode layer 282 may be disposed in a region other than the second semiconductor layer 260, but 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.

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. In addition, the first semiconductor layer 230 may be an n-type semiconductor layer, and the second semiconductor layer 260 may be implemented as 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 extraction structure 284 may be formed in a part or the entire area of the light transmissive electrode layer (not shown) or 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 transparent electrode layer (not shown) or the upper surface of the second semiconductor layer 260, but is not limited thereto. The etching process may include a wet or / and dry etching process, and as the etching process is performed, an upper surface of the light transmissive electrode layer (not shown) or an upper surface of the second semiconductor layer 260 may form a light extraction structure 284. Roughness may be included. 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. As the light extracting structure 284 is formed on the transparent electrode layer (not shown) or on the upper surface of the second semiconductor layer 260, the light generated from the active layer 250 is transmitted to the transparent electrode layer (not shown) or the second semiconductor layer. Since total reflection from the upper surface of 260 may be prevented from being reabsorbed or scattered, it may contribute to the 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. 8 is an enlarged cross-sectional view of a region B of FIG. 7.

Referring to FIG. 8, the active layer 250 of the light emitting device 200 may have a multi-quantum well structure, and thus the active layer 230 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).

Meanwhile, in FIG. 8, the first to third well layers Q1, Q2, and Q3 and the first to third barrier layers B1, B2, and B3 are formed, respectively, and the first to third barrier layers B1, B2, B3) and the first to third well layers Q1, Q2, and Q3 are alternately formed, but are not limited thereto, and the well layers Q1, Q2, and Q3 and the barrier layers B1, B2, and B3 may be alternately formed. ) 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 8.

9 and 10 are diagrams illustrating energy band diagrams of a light emitting device according to an embodiment. In addition, the content common to the content demonstrated in FIG. 3 and FIG. 4 is abbreviate | omitted.

9 and 10, the band gap of the first well layer Q1 may be larger than the band gaps of the second and third well layers Q2 and Q3, and the band gap of the first well layer Q1 may be formed. The thickness may be thicker than the thicknesses of the second and third well layers Q2 and Q3.

As described above, as the first well layer Q1 adjacent to the first semiconductor layer 220 for injecting holes is formed to have a larger band gap, the first to third well layers Q1, Q2, and Q3. The hole injection efficiency of the can be improved, and thus the luminous efficiency of the light emitting device 200 can be improved and the reliability can be improved.

The In content of the first well layer Q1 may be 90% to 99% of the In content of the second and third well layers Q2 and Q3. The reason for limiting the ratio is as described above.

Further, according to the embodiment, the first well layer Q1 formed adjacent to the first semiconductor layer 220 may have a thickness d1, the second well layer Q2 may have a thickness d2, and d1 may be greater than d2. It can have a large value. Preferably, d1 may have a thickness of 110% to 150% relative to d2. The reason for limiting the ratio is as described above.

According to the embodiment, the thickness of the first well layer Q1 is formed to be thicker than the thickness of the second well layer Q2, so that the band gaps between the well layers Q1, Q2, and Q3 are different. The energy level of light generated in Q2 and Q3) may be uniform, and thus, the broadening of the emission spectrum of the light emitting device 200 may be reduced, and the occurrence of shoulders in the optical luminescence spectrum may be reduced. Therefore, a good well structure is formed, the light emitting efficiency of the light emitting device 200 is improved, and shifting to a short wavelength may not occur.

Meanwhile, as illustrated in FIG. 10, the band gaps of the first to third well layers Q1, Q2, and Q3 may be sequentially formed to be small, and the first to third well layers Q1, Q2 and Q3. The thickness of may be formed to have a small thickness sequentially.

Therefore, the content of In included in the first to third quantum well layers Q1, Q2, and Q3 may be sequentially increased from the first well layer Q1 to the third well layer Q3.

As the first layer Q1, Q2, and Q3 are formed to have a larger band gap, the holes of the first to third well layers Q1, Q2, and Q3 are formed closer to the first semiconductor layer 220 to inject holes. The injection efficiency may be improved, and thus, the luminous efficiency of the light emitting device 200 may be improved and reliability may be improved.

In addition, as described above, the well layers Q1, Q2, and Q3 have a larger band gap, and are formed to have a thicker thickness, and even though the band gaps between the well layers Q1, Q2, and Q3 are different, the well layers Q1 and Q2 are different. , The energy level of the light generated in Q3) can be made uniform, so that the broadening of the emission spectrum of the light emitting device 200 can be reduced, and the occurrence of shoulders in the photoluminescence spectrum can be reduced. Therefore, a good well structure is formed, the light emitting efficiency of the light emitting device 200 is improved, and shifting to a short wavelength may not occur.

11 to 13 are a perspective view and a cross-sectional view showing a light emitting device package according to the embodiment.

11 to 13, the light emitting device package 500 includes a body 510 having a cavity 520, first and second lead frames 540 and 550 mounted on the body 510, and a first one. And a light emitting device 530 electrically connected to the second lead frames 540 and 550, and an encapsulant (not shown) filled in the cavity 520 to cover the light emitting device 530.

The body 510 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 510 may be formed by injection molding, etching, or the like, but is not limited thereto.

The inner surface of the body 510 may be formed with an inclined surface. The reflection angle of the light emitted from the light emitting device 530 can be changed according to the angle of the inclined surface, and thus the directivity angle of the light emitted to the outside can be controlled.

Concentration of light emitted to the outside from the light emitting device 530 increases as the directivity angle of light decreases. Conversely, as the directivity angle of light increases, the concentration of light emitted from the light emitting device 530 decreases.

The shape of the cavity 520 formed in the body 510 may be circular, rectangular, polygonal, elliptical, or the like, and may have a curved shape, but the present invention is not limited thereto.

The light emitting device 530 is mounted on the first lead frame 540 and may be, for example, a light emitting device emitting light of red, green, blue, white, or UV (ultraviolet) light emitting device emitting ultraviolet light. But it is not limited thereto. In addition, one or more light emitting elements 530 may be mounted.

The light emitting device 530 may be a horizontal type or a vertical type formed on the upper or lower surface of the light emitting device 530 or a flip chip Applicable.

Meanwhile, the light emitting device 530 according to the embodiment includes an active layer (not shown), and the active layer (not shown) has a multi-quantum well structure including a plurality of well layers, and the plurality of well layers is a P-type semiconductor layer. The bandgap of the well layer adjacent to is formed large, and the thickness of the well layer adjacent to the P-type semiconductor layer is formed thick, so that the luminous efficiency of the light emitting device 530 and the light emitting device package 500 may be improved.

The encapsulant (not shown) may be filled in the cavity 520 to cover the light emitting device 530.

The encapsulant (not shown) may be formed of silicon, epoxy, or other resin material. The encapsulant may be filled in the cavity 520 and ultraviolet or thermally cured.

In addition, the encapsulant (not shown) may include a phosphor, and the phosphor may be selected to be a wavelength of light emitted from the light emitting device 530 so that the light emitting device package 500 may emit white light.

The phosphor may be one of a blue light emitting phosphor, a blue light emitting phosphor, a green light emitting phosphor, a sulfur 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 depending on the wavelength of light emitted from the light emitting device 530 Can be applied.

That is, the phosphor may be excited by the light having the first light emitted from the light emitting device 530 to generate the second light. For example, when the light emitting element 530 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 blue light and blue light emitted from the blue light emitting diode As the excited yellow light is mixed, the light emitting device package 500 can provide white light.

Similarly, when the light emitting element 530 is a green light emitting diode, the magenta phosphor or the blue and red phosphors are mixed, and when the light emitting element 530 is a red light emitting diode, the cyan phosphors or the blue and green phosphors are mixed 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 540 and 550 may be formed of a metal material such as titanium, copper, nickel, gold, chromium, tantalum, (Pt), tin (Sn), silver (Ag), phosphorus (P), aluminum (Al), indium (In), palladium (Pd), cobalt (Co), silicon (Si), germanium , Hafnium (Hf), ruthenium (Ru), and iron (Fe). Also, the first and second lead frames 540 and 550 may be formed to have a single layer or a multilayer structure, but the present invention is not limited thereto.

The first and second lead frames 540 and 550 are separated from each other and electrically separated from each other. The light emitting device 530 is mounted on the first and second lead frames 540 and 550, and the first and second lead frames 540 and 550 are in direct contact with the light emitting device 530 or a soldering member (not shown). May be electrically connected through a material having conductivity such as C). In addition, the light emitting device 530 may be electrically connected to the first and second lead frames 540 and 550 through wire bonding, but is not limited thereto. Accordingly, when power is supplied to the first and second lead frames 540 and 550, power may be applied to the light emitting device 530. Meanwhile, a plurality of lead frames (not shown) may be mounted in the body 510 and each lead frame (not shown) may be electrically connected to the light emitting device 530, but is not limited thereto.

Meanwhile, referring to FIG. 13, the light emitting device package 500 according to the embodiment may include an optical sheet 580, and the optical sheet 580 may include a base portion 582 and a prism pattern 584. Can be.

The base portion 582 is made of a transparent material having excellent thermal stability as a support for forming the prism pattern 584. For example, the base portion 582 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 portion 582 may include a phosphor (not shown). As an example, the base portion 582 may be formed by curing the phosphor (not shown) evenly in a state in which the base portion 582 is uniformly dispersed. As such, when the base portion 582 is formed, the phosphor (not shown) may be uniformly distributed over the base portion 582.

On the other hand, a three-dimensional prism pattern 584 that refracts and collects light may be formed on the base portion 582. The material constituting the prism pattern 584 may be acrylic resin, but is not limited thereto.

The prism pattern 584 includes a plurality of linear prisms arranged in parallel with one another in one direction on one surface of the base portion 582, and a vertical cross section of the linear prism in the axial direction may be triangular.

Since the prism pattern 584 has the effect of condensing light, when the optical sheet 580 is attached to the light emitting device package 500 of FIG. 6C, the linearity of the light is improved, so that the brightness of the light of the light emitting device package 500 is increased. Can be improved.

On the other hand, the prism pattern 584 may include a phosphor (not shown).

The phosphor (not shown) is uniformly formed in the prism pattern 584 by forming the prism pattern 584 in a dispersed state, for example, by mixing with an acrylic resin to form a paste or slurry, and then forming the prism pattern 584. Can be included.

As such, when the phosphor (not shown) is included in the prism pattern 584, the uniformity and distribution of the light of the light emitting device package 500 may be improved, and in addition to the light condensing effect by the prism pattern 584, the phosphor (not shown) may be used. Due to the light scattering effect, the directivity of the light emitting device package 500 can be improved.

A plurality of light emitting device packages 500 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 500. 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.

14 is a perspective view illustrating a lighting apparatus including a light emitting device package according to an embodiment, and FIG. 15 is a cross-sectional view illustrating a C-C 'cross section of the lighting apparatus of FIG. 14.

Referring to FIGS. 14 and 15, the lighting device 600 may include a body 610, a cover 630 fastened to the body 610, and a closing cap 650 located at both ends of the body 610. have.

A light emitting device module 640 is coupled to a lower surface of the body 610. The body 610 is electrically conductive so that heat generated from the light emitting device package 644 can be emitted to the outside through the upper surface of the body 610. [ And a metal material having an excellent heat dissipation effect.

The light emitting device package 644 may be mounted on the PCB 642 in a multi-color, multi-row manner to form an array. The light emitting device package 644 may be mounted at equal intervals or may be mounted with various spacings as required. As the PCB 642, MPPCB (Metal Core PCB) or FR4 material PCB can be used.

In particular, the light emitting device package 644 includes a light emitting device (not shown), the light emitting device (not shown) includes an active layer (not shown), and the active layer (not shown) includes a multi quantum well including a plurality of well layers. The structure of the plurality of well layers includes a plurality of well layers in which a band gap of a well layer adjacent to the P-type semiconductor layer is large, and a thickness of the well layer adjacent to the P-type semiconductor layer is thick, thereby forming a light emitting device package 644. ) And the luminous efficiency of the lighting device 600 can be improved.

Since the light emitting device package 644 may have an improved heat dissipation function including an extended lead frame (not shown), reliability and efficiency of the light emitting device package 644 may be improved, and the light emitting device package 622 and the light emitting device may be improved. The service life of the lighting device 600 including the device package 644 may be extended.

The cover 630 may be formed in a circular shape to surround the lower surface of the body 610, but is not limited thereto.

The cover 630 protects the internal light emitting element module 640 from foreign substances or the like. In addition, the cover 630 may include diffusing particles to prevent glare of the light generated from the light emitting device package 644, 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 630. 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 630.

On the other hand, since the light generated from the light emitting device package 644 is emitted to the outside through the cover 630, the cover 630 should have excellent light transmittance, and has sufficient heat resistance to withstand the heat generated from the light emitting device package 644. The cover 630 is preferably formed of a material including polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), or the like. .

Closing cap 650 is located at both ends of the body 610 may be used for sealing the power supply (not shown). In addition, the closing cap 650, the power pin 652 is formed, the lighting device 600 according to the embodiment can be used immediately without a separate device in the terminal removed the existing fluorescent lamp.

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

FIG. 16 illustrates an edge-light method, and the liquid crystal display 700 may include a liquid crystal display panel 710 and a backlight unit 770 for providing light to the liquid crystal display panel 710.

The liquid crystal display panel 710 may display an image using light provided from the backlight unit 770. The liquid crystal display panel 710 may include a color filter substrate 712 and a thin film transistor substrate 714 facing each other with the liquid crystal interposed therebetween.

The color filter substrate 712 may implement a color of an image displayed through the liquid crystal display panel 710.

The thin film transistor substrate 714 is electrically connected to the printed circuit board 718 on which a plurality of circuit components are mounted through the driving film 717. The thin film transistor substrate 714 may apply a driving voltage provided from the printed circuit board 718 to the liquid crystal in response to a driving signal provided from the printed circuit board 718.

The thin film transistor substrate 714 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 770 may include a light emitting device module 720 for outputting light, a light guide plate 730 for changing the light provided from the light emitting device module 720 into a surface light source, and providing the light to the liquid crystal display panel 710. Reflective sheet for reflecting the light emitted to the light guide plate 730 to the plurality of films 750, 766, 764 and the light guide plate 730 to uniform the luminance distribution of the light provided from the 730 and improve the vertical incidence ( 740.

The light emitting device module 720 may include a PCB substrate 722 for mounting a plurality of light emitting device packages 724 and a plurality of light emitting device packages 724 to form an array.

In particular, the light emitting device package 724 includes a light emitting device (not shown), the light emitting device (not shown) includes an active layer (not shown), and the active layer (not shown) includes a multi quantum well including a plurality of well layers. It has a structure, the plurality of well layer has a large band gap of the well layer adjacent to the P-type semiconductor layer, the thickness of the well layer adjacent to the P-type semiconductor layer is formed thick, so that the light emitting device package 724 and the backlight unit ( The luminous efficiency of 770 may be improved.

Meanwhile, the backlight unit 770 includes a diffusion film 766 for diffusing light incident from the light guide plate 730 toward the liquid crystal display panel 710, and a prism film 750 for condensing the diffused light to improve vertical incidence. It may be configured as), and may include a protective film 764 for protecting the prism film 750.

17 is an exploded perspective view of a liquid crystal display including the light emitting device according to the embodiment. However, the parts illustrated and described in FIG. 16 will not be repeatedly described in detail.

17 is a direct view, the liquid crystal display device 800 may include a liquid crystal display panel 810 and a backlight unit 870 for providing light to the liquid crystal display panel 810.

Since the liquid crystal display panel 810 is the same as that described with reference to FIG. 8, a detailed description thereof will be omitted.

The backlight unit 870 includes a plurality of light emitting device modules 823, a reflective sheet 824, a lower chassis 830 in which the light emitting device modules 823 and the reflective sheet 824 are accommodated, and an upper portion of the light emitting device module 823. It may include a diffusion plate 840 and a plurality of optical film 860 disposed in the.

LED Module 823 A plurality of light emitting device packages 822 and a plurality of light emitting device packages 822 may be mounted to include a PCB substrate 821 to form an array.

In particular, the light emitting device package 822 includes a light emitting device (not shown), the light emitting device (not shown) includes an active layer (not shown), and the active layer (not shown) includes a multi quantum well including a plurality of well layers. It has a structure, the plurality of well layer has a large band gap of the well layer adjacent to the P-type semiconductor layer, the thickness of the well layer adjacent to the P-type semiconductor layer is formed thick, thereby the light emitting device package 822 and the backlight unit ( The luminous efficiency of 870 can be improved.

The reflective sheet 824 reflects light generated from the light emitting device package 822 in the direction in which the liquid crystal display panel 810 is located to improve light utilization efficiency.

Light generated in the light emitting element module 823 is incident on the diffusion plate 840 and an optical film 860 is disposed on the diffusion plate 840. The optical film 860 may include a diffusion film 866, a prism film 850, and a protective film 864.

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

Claims

And a light emitting structure including a first semiconductor layer, a second semiconductor layer, and an active layer formed between the first semiconductor layer and the second semiconductor layer.
At least one of the first semiconductor layer and the second 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,
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 bandgap, the second well layer has a second bandgap smaller than the first bandgap,
The thickness of the first well layer is thicker than the thickness of the second well layer.

The method of claim 1,
The first band gap is,
A light emitting device that is 101% to 110% of the second bandgap.

The method of claim 2,
The thickness of the first well layer is
Light emitting device is 110% to 150% of the thickness of the second well layer.

The method of claim 1,
The well layer includes a third well layer formed between the first well layer and the second well layer,
The third well layer has a third band gap,
The third band gap is,
A light emitting device smaller than the first band gap and larger than the second band gap.

The method of claim 4, wherein
The thickness of the third well layer is
A light emitting device thinner than the first well layer and thicker than the second well layer.

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

The method according to claim 6,
In content of the first well layer,
A light emitting device which is 90% to 99% of the In content of the second well layer.

The method of claim 1,
Disposed between the active layer and the P-type semiconductor layer to prevent leakage current
An intermediate layer; Light emitting device further comprising.

In the eighth place.
Wherein the intermediate layer comprises:
A light emitting device having a band gap larger than the band gap of the barrier layer.

In the eighth place.
Wherein the intermediate layer comprises:
Light emitting element including Al.