KR102076242B1 - A light emitting device - Google Patents

Abstract

An embodiment may include a first conductive semiconductor layer, a second conductive semiconductor layer disposed on the first conductive semiconductor layer, a first conductive semiconductor layer, and a second conductive semiconductor layer. And a carrier injection layer disposed between the active layer and the second conductivity type semiconductor layer and doped with a second conductivity type dopant, wherein the carrier injection layer is formed on the carrier injection layer among the barrier layers. The last adjacent barrier layer comprises at least a portion of the barrier layers having an energy band gap that is larger than the energy band gap of the remaining barrier layers.

Description

Light-Emitting Element {A LIGHT EMITTING DEVICE}

Embodiments relate to a light emitting device.

In the light emitting diode structure, a p-type semiconductor layer, an active layer, and an n-type semiconductor layer are sequentially stacked on a substrate, and a p-type electrode is disposed on the p-type semiconductor layer to supply a driving current. The n-type electrode may be disposed in the n-type semiconductor layer.

When a driving current is supplied to the p-type semiconductor layer and the n-type semiconductor layer through the electrode, holes (+) may be emitted from the p-type semiconductor layer to the active layer, and electrons (-) may be emitted from the n-type semiconductor layer to the active layer. Can be. As a result, holes and electrons are combined in the active layer to lower the energy level, and at the same time, the energy emitted may be emitted in the form of light.

The embodiment provides a light emitting device capable of preventing a decrease in light output due to back diffusion, an increase in operating voltage, and deterioration of crystallinity.

The light emitting device according to the embodiment may include a first conductivity type semiconductor layer; A second conductive semiconductor layer disposed on the first conductive semiconductor layer; An active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer, the active layer including well layers and barrier layers; And a carrier injection layer disposed between the active layer and the second conductivity type semiconductor layer and doped with a second conductivity type dopant, wherein the last barrier layer closest to the carrier injection layer is the barrier. At least a portion of the layers having an energy band gap that is greater than the energy band gap of the remaining barrier layer.

At least a portion of the last barrier layer may comprise aluminum.

The composition of at least a portion of the last barrier layer is Al _a In _b Ga _(1-ab) N (0.03 ≦ a ≦ 0.05, 0 ≦ _b ≦ 0.15), the composition of the last barrier layer excluding at least a portion of the last barrier layer. The composition of the remaining portion may be In _x Ga _(1-x) N (0 ≦ _x ≦ 0.05).

The last barrier layer comprises a first portion adjacent the last well layer closest to the carrier injection layer of the well layers; A third portion adjacent the carrier injection layer; And

And a second portion positioned between the first portion and the third portion, wherein an energy band gap of the second portion may be greater than an energy band gap of each of the first portion and the third portion.

The energy band gap of at least a portion of the last barrier layer may gradually increase or decrease gradually toward the second conductive semiconductor layer in the active layer.

Embodiments can prevent light output degradation due to back diffusion, increase in operating voltage, and deterioration in crystallinity.

1 is a cross-sectional view of a light emitting device according to an embodiment.
FIG. 2 shows the structure of the active layer shown in FIG. 1.
3 illustrates an embodiment of an energy band gap of the light emitting structure illustrated in FIG. 1.
4 illustrates another embodiment of an energy band gap of the light emitting structure illustrated in FIG. 1.
FIG. 5 shows another embodiment of an energy band gap of the light emitting structure shown in FIG. 1.
6 is a sectional view showing a light emitting device according to another embodiment.
7 illustrates a light emitting device package according to an embodiment.
8 illustrates a lighting device including a light emitting device according to the embodiment.
9 illustrates a display device including a light emitting device according to an exemplary embodiment.

Hereinafter, the embodiments will be apparent from the accompanying drawings and the description of the embodiments. In the description of an embodiment, each layer, region, pattern, or structure may be “under” or “under” the substrate, each layer, region, pad, or pattern. In the case where it is described as being formed at, "up" and "under" include both "directly" or "indirectly" formed through another layer. do. In addition, the criteria for up / down or down / down each layer will be described with reference to the drawings.

In the drawings, sizes are exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size. Like reference numerals denote like elements throughout the description of the drawings. Hereinafter, a light emitting device according to an embodiment will be described with reference to the accompanying drawings.

 1 illustrates a cross-sectional view of a light emitting device 100 according to an embodiment, FIG. 2 illustrates a structure of the active layer 124 illustrated in FIG. 1, and FIG. 3 illustrates an energy band of the light emitting structure 120 illustrated in FIG. 1. An embodiment of the gap is shown.

Referring to FIG. 1, the light emitting device 100 includes a substrate 110, a buffer layer 115, a light emitting structure 120, a conductive layer 130, a first electrode 142, and a second electrode 144. do.

The substrate 110 supports the light emitting structure 120. The substrate 110 may be a material suitable for growing a semiconductor material. In addition, the substrate 110 may be a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. For example, the substrate 110 may be sapphire (Al ₂ O ₃ ) or a material including at least one of GaN, SiC, ZnO, Si, GaP, InP, Ga ₂ O ₃ , GaAs. Unevenness may be formed on the upper surface of the substrate 110 to improve light extraction.

The buffer layer 115 is disposed between the substrate 110 and the light emitting structure 120, and the lattice mismatch caused by the difference in the lattice constant between the substrate 110 and the light emitting structure 120 is alleviated to determine the light emitting structure 120. Can improve the sex.

The buffer layer 115 may be a nitride semiconductor including a Group 3 element and a Group 5 element.

For example, the buffer layer 115 may include at least one of InAlGaN, GaN, AlN, AlGaN, InGaN. The buffer layer 115 may have a single layer or a multilayer structure, and a group 2 or group 4 element may be doped with impurities.

In addition, an undoped semiconductor layer (not shown) may be interposed between the first conductive semiconductor layer 122 and the buffer layer 115 to improve the crystallinity of the first conductive semiconductor layer 122. The undoped semiconductor layer may have the same composition as the first conductive semiconductor layer 122 except that the n-type dopant is not doped and thus has a lower electrical conductivity than the first conductive semiconductor layer 122.

The light emitting structure 120 is disposed on the substrate 110 and may generate light. The light emitting structure 120 may include a first conductive semiconductor layer 122, an active layer 124, a carrier injection layer 125, an electron blocking layer 126, and a second conductive semiconductor layer ( 127).

The first conductivity type semiconductor layer 122 may be disposed on the buffer layer 115, may be a nitride semiconductor layer, and may be doped with the first conductivity type dopant. The first conductive semiconductor layer 122 is a semiconductor material having a composition formula of In _x Al _y Ga _(1-xy) N (0≤x≤1, 0≤y≤1, 0≤x + y≤1), for example For example, it may be selected from GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, and the like, and n-type dopants such as Si, Ge, Sn, Se, Te, and the like may be doped.

The active layer 124 is disposed between the first conductive semiconductor layer 122 and the second conductive semiconductor layer 127. The active layer 124 is formed by energy generated in the process of recombination of electrons provided from the first conductive semiconductor layer 122 and holes provided from the second conductive semiconductor layer 127. Can produce light.

The active layer 124 may be a semiconductor having a composition formula of In _x Al _y Ga _{1 -xy} N (0 <x ≦ 1, 0 ≦ y <1, 0 ≦ x + y ≦ 1). The active layer 124 includes a quantum well layer (QW1 to QWn, a natural number of n≥1, see FIG. 2) and a quantum barrier layer (QB1 to QBn, a natural number of n≥1, see FIG. 2) alternately arranged one or more times. It may be a quantum well structure comprising.

For example, the active layer 124 may have a multi quantum well (MQW) structure. The energy band gaps E1, E3, E4, and E5 of the quantum barrier layers QB1 to QBm and m ≧ 1 are greater than the energy band gap E2 of the quantum well layers QW1 to QWn and n ≧ 1. Can be large.

The second conductive semiconductor layer 127 may be disposed on the active layer 124, may be a nitride semiconductor layer, and may be doped with the second conductive dopant. The second conductive semiconductor layer 127 is a semiconductor material having a composition formula of In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1), for example GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, and the like, and may be doped with p-type dopants such as Mg, Zn, Ca, Sr, and Ba.

The electron blocking layer 126 is disposed between the active layer 124 and the second conductive semiconductor layer 127, and electrons injected from the first conductive semiconductor layer 122 into the active layer 124 are second conductive semiconductors. Overflowing to layer 127 can be prevented to prevent leakage current. Therefore, the energy band gap E7 of the electron blocking layer 126 is larger than the energy band gaps E1, E3, E4, and E5 of the quantum barrier layers QB1 to QBn, a natural number of n> 1.

The electron blocking layer 126 may be a nitride semiconductor layer including aluminum (Al) (eg, Al _x Ga _(1-x) N, 0.12 ≦ _x ≦ 0.2), and may be disposed in a portion of the electron blocking layer 126. The content of aluminum included may be greater than the aluminum content included in the remaining other regions. In addition, the electron blocking layer 126 may be a nitride semiconductor layer (eg, InAlGaN) including aluminum and indium.

The electron blocking layer 126 may be doped with a second conductivity type dopant (eg, Mg, Zn, Ca, Sr, or Ba) to smoothly move the hole. The electron blocking layer 126 may have a thickness of 30 nm to 50 nm.

The conductive layer 130 may be disposed on the second conductive semiconductor layer 127, and may not only reduce total reflection, but also increase light extraction efficiency of the light emitted from the active layer 124 because of good light transmittance.

The conductive layer 130 may be formed of a transparent conductive oxide, such as indium tin oxide (ITO), tin oxide (TO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), indium aluminum zinc oxide (IZAZO), or IGZO (IGZO). Indium Gallium Zinc Oxide, IGTO, Aluminum Zinc Oxide, AZO, Antimony Tin Oxide, ATO, Gallium Zinc Oxide / Au, or Ni / IrOx / Au / ITO can be used to form a single layer or multiple layers.

The first electrode 142 may be disposed on the first conductive semiconductor layer 142, and the second electrode 144 may be disposed on the conductive layer 130. A portion of the light emitting structure 120 may be etched to expose a region of the first conductive semiconductor layer 142, and the first electrode 142 may be disposed on a region of the first conductive semiconductor layer 142 that is exposed. Can be placed in.

The first electrode 142 and the second electrode 144 may be formed of a conductive material, such as Ti, Al, Al alloy, In, Ta, Pd, Co, Ni, Si, Ge, Ag, Ag alloy, Au, Hf, It may be formed by including at least one of Pt, Ru or Au, or may be formed of an alloy containing at least one, the form may be a single layer or a multi-layer.

The carrier injection layer 125 may be disposed between the active layer 124 and the electron blocking layer 126, and may be doped with the second conductivity type dopant. The carrier injection layer 125 may improve the light output of the light emitting device 100 by injecting a carrier (eg, a hole) into the active layer 124.

The carrier injection layer 125 may be a layer doped with a p-type dopant (eg, Mg) to inject holes into the active layer 124. The composition of the carrier injection layer 125 may be In _x Al _y Ga _(1-xy) N, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and the thickness may be 4 nm to 8 nm. When the thickness of the carrier injection layer 125 is less than 4 nm, the carrier injection role may not be performed, and when the thickness of the carrier injection layer 125 is greater than 8 nm, crystallinity of the light emitting device may deteriorate.

The energy band gap E6 of the carrier injection layer 125 may decrease from the active layer 124 toward the second conductivity type semiconductor layer 127. The minimum value of the energy band gap of the carrier injection layer 125 may be larger than the energy band gap E1 of the well layers (QW1 to QWn, n> 1) of the active layer 124.

As shown in FIGS. 2 and 3, the barrier layer QBn (hereinafter referred to as “last barrier”) closest to the carrier injection layer 125 among the barrier layers QB1 to QBn (n> 1 of natural water) of the active layer 124. Layer ”may be thicker than the thickness of the remaining barrier layers QB1 to QB (n−1).

This makes the thickness of the last barrier layer Qn thicker, such that the p-type dopant (eg, Mg) of the carrier injection layer 125 is closest to the carrier injection layer 125 of the well layers of the active layer 124. (QWn, hereinafter referred to as "last well layer") to prevent diffusion.

For example, the thickness t1 of the barrier layer Qn closest to the carrier injection layer 125 may be 5 nm to 9 nm, and the thickness t2 of the remaining barrier layers may be 3 nm to 4 nm.

In general, when the p-type dopant (eg, Mg) of the carrier injection layer diffuses into the last well layer (hereinafter referred to as "back diffusion"), the light output of the light emitting device may drop, and the operating voltage This can rise, deteriorating the crystallinity of the light emitting structure, which can deteriorate the reliability of the light emitting device.

As shown in FIGS. 2 and 3, the energy band gap E4 of at least a portion (eg, B2) of the last barrier layer QBn of the active layer 124 is the energy band of the remaining portions (eg, B1, B3). It may be larger than the gaps E3 and E5.

At least a portion (eg B2) of the last barrier layer QBn may be a nitride semiconductor layer comprising aluminum (Al), such as AlGaN, or InAlGaN. The remainder of the last barrier layer QBn (e.g., B1, B3) is a nitride semiconductor layer that does not contain aluminum (Al), for example. It may be GaN or InGaN.

The reason why aluminum is included in at least a portion B2 of the last barrier layer QBn is that aluminum (Al) plays a role in preventing back diffusion.

That is, the ability of AlGaN to prevent diffusion of the dopant (Mg) of the carrier injection layer 125 into the last well layer may be greater than that of GaN.

The composition of at least a portion of the last barrier layer QBn (eg, B2) may be Al _a In _b Ga _(1-ab) N, 0.03 ≦ a ≦ 0.05, 0 ≦ _b ≦ 0.15, and the last barrier layer QBn The composition of the remaining portion (eg, B1, B3) may be In _x Ga _(1-x) N, 0≤x≤0.05.

If the aluminum content of at least a portion of the last barrier layer QBn (eg, B2) exceeds 5%, the operating voltage of the light emitting device 100 may increase, and if less than 3%, the back diffusion is prevented. Can not.

The thickness t3 of at least a portion (eg, B2) of the last barrier layer QBn may be between 3 nm and 6 nm. If the thickness t3 of at least a portion of the last barrier layer QBn (eg, B2) is greater than 6 nm, the operating voltage of the light emitting device 100 may increase, and if less than 3 nm, back diffusion may be prevented. none.

At least a portion B2 of the last barrier layer QBn may be positioned to be spaced apart from the last well layer QWn. Since at least a portion B2 of the last barrier layer QBn contains aluminum, a difference in lattice constant from the last well layer QWn may be large. Therefore, when at least a portion B2 of the last barrier layer QBn is in contact with the last well layer QWn, the crystallinity of the light emitting structure may be deteriorated, thereby degrading reliability of the light emitting device.

For example, the last barrier layer QBn may include a first portion B1 adjacent to the last well layer QWn, a third portion B3 adjacent to the carrier injection layer 125, a first portion B1 and a third portion. It may comprise a second part (B2) located between the parts (B3).

The energy band gap E4 of the second part B2 may be larger than the energy band gap E3 of the first part B1 and the energy band gap E5 of the third part B3. The energy band gap E4 of the second portion B2 may be constant.

The energy band gap B4 of the second portion B2 may be smaller than the energy band gap E7 of the electron blocking layer 126.

The composition of the second portion B2 may be Al _a In _b Ga _(1-ab) N, 0.03 ≦ a ≦ 0.05, 0 ≦ _b ≦ 0.15), and the first portion B1 and the third portion B3 The composition of may be In _x Ga _(1-x) N, 0≤x≤0.05. The thickness t3 of the second portion B2 may be 3 nm to 6 nm.

Although the last barrier layer QBn shown in FIGS. 1 to 3 includes only one second portion B2, the last barrier layer QBn of another embodiment may include two or more second portions spaced apart from each other. have. The composition of the remaining portions of the last barrier layer QBn excluding the two or more second portions, and the energy band gap may be the same as described with reference to FIGS.

Embodiments can prevent back diffusion by at least a portion of the last barrier layer (QBn) comprising aluminum, wherein the light output of the light emitting device 100 due to the back diffusion, an increase in operating voltage, and crystallization It can prevent deterioration.

In addition, since the embodiment may prevent back diffusion, the concentration of the dopant (eg, Mg) of the carrier injection layer 125 may be increased, thereby increasing the injection amount of holes into the active layer 124. The light output of the light emitting device 100 can be improved.

Further, the embodiment may suppress the overflow of electrons from the active layer 124 to the second conductivity type semiconductor layer since the energy band gap of at least a portion of the last barrier layer QBn is larger than the energy band gap of the remaining portion. The efficiency droop of the light emitting device 100 may be alleviated by an increase in current.

4 illustrates another embodiment of an energy band gap of the light emitting structure 120 illustrated in FIG. 1. The same reference numerals as in FIG. 3 represent the same configuration, and the description of the same configuration will be simplified or omitted.

Referring to FIG. 4, the energy band gap E4 ′ of at least a portion B2 ′ of the last barrier layer QBn toward the second conductive semiconductor layer 127 from the first conductive semiconductor layer 122. May increase gradually.

At least a portion (eg, B 2 ′) of the last barrier layer QBn may be a nitride semiconductor layer comprising aluminum (Al), such as AlGaN, or InAlGaN. The remainder of the last barrier layer QBn (e.g., B1, B3) is a nitride semiconductor layer that does not contain aluminum (Al), for example. It may be GaN or InGaN.

As the direction from the first conductive semiconductor layer 122 to the second conductive semiconductor layer 127 is increased, the aluminum (Al) content of at least a portion (eg, B2 ′) of the last barrier layer QBn may gradually decrease. This is to lower the operating voltage by reducing the interface resistance between at least a portion (eg B2 ′) and the remaining portions (eg B1, B2) of the last barrier layer QBn.

The reason for gradually decreasing the aluminum (Al) content of at least a portion (eg, B2 ') of the last barrier layer QBn is to allow the hole from the carrier injection layer 125 to easily pass over to the last well layer QWn. .

5 illustrates another embodiment of an energy band gap of the light emitting structure 120 illustrated in FIG. 1. The same reference numerals as in FIG. 3 represent the same configuration, and the description of the same configuration will be simplified or omitted.

Referring to FIG. 5, the energy band gap E4 ″ of at least a portion B2 ″ of the last barrier layer QBn toward the second conductivity type semiconductor layer 122 from the first conductivity type semiconductor layer 122 is May decrease gradually.

As the direction from the first conductive semiconductor layer 122 to the second conductive semiconductor layer 127 increases, the aluminum (Al) content of at least a portion (eg, B2 ″) of the last barrier layer QBn may gradually increase. This is to lower the operating voltage by reducing the interface resistance between at least a portion (eg B2 ″) and the remaining portions (eg B1, B2) of the last barrier layer QBn.

The reason for gradually increasing the aluminum (Al) content of at least a portion of the last barrier layer QBn (eg, B2 ") is to allow the holes from the carrier injection layer 125 to easily pass over to the last well layer QWn. .

6 is a sectional view of a light emitting device 200 according to another embodiment.

Referring to FIG. 6, the light emitting device 200 includes a second electrode 405, a protective layer 440, a current blocking layer 445, a light emitting structure 120, a passivation layer 465, and a second electrode 405. One electrode 470 is included.

The second electrode 405 together with the first electrode 470 provides power to the light emitting structure 120. The second electrode 405 includes a support layer 410, a bonding layer 415, a barrier layer 420, a reflective layer 425, and an ohmic layer 430. It may include.

The support substrate 410 supports the light emitting structure 120. The support substrate 410 may be formed of a metal or a semiconductor material. In addition, the support substrate 410 may be formed of a material having high electrical conductivity and thermal conductivity. For example, the support substrate 410 includes at least one of copper (Cu), copper alloy (Cu alloy), gold (Au), nickel (Ni), molybdenum (Mo), and copper-tungsten (Cu-W). It may be a metal material or a semiconductor including at least one of Si, Ge, GaAs, ZnO, and SiC.

The bonding layer 415 may be disposed between the supporting substrate 410 and the barrier layer 420, and may serve as a bonding layer for bonding the supporting substrate 410 and the barrier layer 420. . The bonding layer 415 may include at least one of a metal material, for example, In, Sn, Ag, Nb, Pd, Ni, Au, and Cu. Since the bonding layer 415 is formed to bond the supporting substrate 410 by a bonding method, the bonding layer 215 may be omitted when the supporting substrate 410 is formed by a plating or deposition method.

The barrier layer 420 is disposed under the reflective layer 425, the ohmic region 430, and the protective layer 440, and the metal ions of the bonding layer 415 and the supporting substrate 410 are reflected layer 425, and The diffusion of the light emitting structure 120 through the ohmic region 430 may be prevented. For example, the barrier layer 420 may include at least one of Ni, Pt, Ti, W, V, Fe, and Mo, and may include a single layer or multiple layers.

The reflective layer 425 may be disposed on the barrier layer 420 and may reflect light incident from the light emitting structure 120, thereby improving light extraction efficiency. The reflective layer 425 may be formed of a metal or an alloy including at least one of a light reflective material such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf.

The reflective layer 425 may be formed in a multilayer using a metal or an alloy and a light-transmitting conductive material such as IZO, IZTO, IAZO, IGZO, IGTO, AZO, or ATO. For example, IZO / Ni, AZO / Ag, IZO / Ag / Ni, AZO / Ag / Ni and the like.

The ohmic region 430 may be disposed between the reflective layer 425 and the second conductive semiconductor layer 127. The ohmic region 430 may be in ohmic contact with the second conductive semiconductor layer 127 to contact the light emitting structure 120. Power can be supplied smoothly.

The ohmic region 430 may be formed by selectively using a light transmissive conductive layer and a metal. For example, the ohmic region 430 may be a metal material in ohmic contact with the second conductive semiconductor layer 127, for example, at least one of Ag, Ni, Cr, Ti, Pd, Ir, Sn, Ru, Pt, Au, and Hf. It may include.

The protective layer 440 may be disposed on an edge region of the second electrode 405. For example, the protective layer 440 is on an edge region of the ohmic region 430, an edge region of the reflective layer 425, an edge region of the barrier layer 420, or an edge region of the support substrate 410. Can be placed in.

The protective layer 440 may prevent the interface between the light emitting structure 120 and the second electrode 405 from being peeled off, thereby reducing the reliability of the light emitting device 200. Protective layer 440 may be an electrically insulating material, such as ZnO, SiO ₂ , Si ₃ N ₄ , TiOx (x is a positive real number), or Al ₂ O ₃ Or the like.

The current blocking layer 445 may be disposed between the ohmic region 430 and the light emitting structure 120. An upper surface of the current blocking layer 445 may contact the second conductive semiconductor layer 127, and a lower surface, or a lower surface and a side surface of the current blocking layer 445 may contact the ohmic region 430. The current blocking layer 445 may be disposed to overlap at least a portion of the first electrode 470 in the vertical direction.

The current blocking layer 445 may be formed between the ohmic region 430 and the second conductive semiconductor layer 127, or may be formed between the reflective layer 425 and the ohmic region 430, but is not limited thereto.

The light emitting structure 120 may be disposed on the ohmic region 430 and the protective layer 440, and may be the same as described with reference to FIGS. 1 to 3.

The side surface of the light emitting structure 120 may be an inclined surface in an isolation etching process divided into unit chips.

The passivation layer 465 may be disposed on the side of the light emitting structure 120 to electrically protect the light emitting structure 120. The passivation layer 465 may be disposed on a portion of the top surface of the first conductivity type semiconductor layer 122 or the top surface of the protective layer 440. The passivation layer 465 may be formed of an insulating material such as SiO ₂ , SiO _x , SiO _x N _y , Si ₃ N ₄ , or Al ₂ O ₃ to be formed Can be.

The first electrode 470 may be disposed on the first conductivity type semiconductor layer 122 and may have a predetermined pattern shape. A roughness pattern (not shown) may be formed on the top surface of the first conductive semiconductor layer 122 to increase light extraction efficiency. In addition, a roughness pattern (not shown) may be formed on the top surface of the first electrode 470 to increase light extraction efficiency.

The light emitting device 200 according to the embodiment may prevent back diffusion by at least a portion of the last barrier layer QBn including aluminum, and reduce light output of the light emitting device 100 due to the back diffusion, An increase in operating voltage and deterioration of crystallinity can be prevented.

In addition, the embodiment may increase the concentration of the dopant (eg, Mg) of the carrier injection layer 125, and may improve the light output of the light emitting device 100. In addition, the embodiment may alleviate the efficiency droop of the light emitting device 100 according to the increase of the current.

7 illustrates a light emitting device package according to an embodiment.

Referring to FIG. 7, the light emitting device package may include a package body 510, a first metal layer 512, a second metal layer 514, a light emitting device 520, a reflective plate 530, a wire 530, and a resin layer ( 540).

The package body 510 may be formed of a substrate having good insulation or thermal conductivity, such as a silicon-based wafer level package, a silicon substrate, silicon carbide (SiC), aluminum nitride (AlN), or the like. It may have a structure in which a plurality of substrates are stacked. Embodiment is not limited to the material, structure, and shape of the body described above.

The package body 510 may have a cavity consisting of side and bottom in one region of the upper surface. At this time, the side wall of the cavity may be formed to be inclined.

The first conductive layer 512 and the second conductive layer 514 are disposed on the surface of the package body 510 to be electrically separated from each other in consideration of heat dissipation or mounting of a light emitting device. The light emitting device 520 is electrically connected to the first conductive layer 512 and the second conductive layer 514. In this case, the light emitting device 520 may be embodiments 100 and 200.

The reflective plate 530 may be disposed on the side wall of the cavity of the package body 510 to direct light emitted from the light emitting element 520 in a predetermined direction. The reflector plate 530 is made of a light reflective material, and may be, for example, a metal coating or a metal flake.

The resin layer 540 surrounds the light emitting device 520 positioned in the cavity of the package body 510 to protect the light emitting device 520 from the external environment. The resin layer 540 may be made of a colorless transparent polymer resin material such as epoxy or silicon. The resin layer 540 may include a phosphor to change the wavelength of light emitted from the light emitting element 520.

A plurality of light emitting device packages may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, and the like, which are optical members, may be disposed on an optical path of the light emitting device package. The light emitting device package, the substrate, and the optical member may function as a backlight 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.

8 illustrates a lighting device including a light emitting device according to the embodiment.

Referring to FIG. 8, the lighting apparatus may include a cover 1100, a light source module 1200, a heat sink 1400, a power supply 1600, an inner case 1700, and a socket 1800. In addition, the lighting apparatus according to the embodiment may further include any one or more of the member 1300 and the holder 1500.

The light source module 1200 may include the light emitting devices 100 and 200, or the light emitting device package illustrated in FIG. 7.

The cover 1100 may have a shape of a bulb or hemisphere, may be hollow, and may have a shape in which a portion thereof is opened. The cover 1100 may be optically coupled to the light source module 1200. For example, the cover 1100 may diffuse, scatter, or excite light provided from the light source module 1200. The cover 1100 may be a kind of optical member. The cover 1100 may be combined with the heat sink 1400. The cover 1100 may have a coupling portion coupled to the heat sink 1400.

The inner surface of the cover 1100 may be coated with a milky paint. The milky paint may include a diffuser that diffuses light. The surface roughness of the inner surface of the cover 1100 may be greater than the surface roughness of the outer surface of the cover 1100. This is for the light from the light source module 1200 to be sufficiently scattered and diffused to be emitted to the outside.

The material of the cover 1100 may be glass, plastic, polypropylene (PP), polyethylene (PE), polycarbonate (PC), or the like. Here, polycarbonate is excellent in light resistance, heat resistance, and strength. The cover 1100 may be transparent so that the light source module 1200 is visible from the outside, but is not limited thereto and may be opaque. The cover 1100 may be formed through blow molding.

The light source module 1200 may be disposed on one surface of the heat sink 1400, and heat generated from the light source module 1200 may be conducted to the heat sink 1400. The light source module 1200 may include a light source unit 1210, a connection plate 1230, and a connector 1250.

The member 1300 may be disposed on an upper surface of the heat sink 1400 and has a plurality of light source units 1210 and a guide groove 1310 into which the connector 1250 is inserted. The guide groove 1310 may correspond to or be aligned with the substrate and the connector 1250 of the light source 1210.

The surface of the member 1300 may be coated or coated with a light reflecting material.

For example, the surface of the member 1300 may be coated or coated with a white paint. The member 1300 may reflect light reflected from the inner surface of the cover 1100 and returned toward the light source module 1200 in the direction of the cover 1100. Therefore, it is possible to improve the light efficiency of the lighting apparatus according to the embodiment.

The member 1300 may be made of an insulating material, for example. The connection plate 1230 of the light source module 1200 may include an electrically conductive material. Therefore, electrical contact may be made between the heat sink 1400 and the connection plate 1230. The member 1300 may be made of an insulating material to block an electrical short between the connection plate 1230 and the heat sink 1400. The radiator 1400 may receive heat from the light source module 1200 and heat from the power supply 1600 to radiate heat.

The holder 1500 blocks the accommodating groove 1719 of the insulating portion 1710 of the inner case 1700. Therefore, the power supply unit 1600 accommodated in the insulating unit 1710 of the inner case 1700 may be sealed. The holder 1500 may have a guide protrusion 1510, and the guide protrusion 1510 may have a hole through which the protrusion 1610 of the power supply 1600 passes.

The power supply unit 1600 processes or converts an electrical signal provided from the outside to provide the light source module 1200. The power supply 1600 may be accommodated in the accommodating groove 1725 of the inner case 1700, and may be sealed in the inner case 1700 by the holder 1500. The power supply 1600 may include a protrusion 1610, a guide 1630, a base 1650, and an extension 1670.

The guide part 1630 may have a shape protruding to the outside from one side of the base 1650. The guide part 1630 may be inserted into the holder 1500. A plurality of parts may be disposed on one surface of the base 1650. For example, a plurality of components may include, for example, a DC converter for converting an AC power provided from an external power source into a DC power source, a driving chip for controlling driving of the light source module 1200, and an ESD (ElectroStatic) to protect the light source module 1200. discharge) protection elements and the like, but is not limited thereto.

The extension 1670 may have a shape protruding to the outside from the other side of the base 1650. The extension 1670 may be inserted into the connection 1750 of the inner case 1700, and may receive an electrical signal from the outside. For example, the extension 1670 may have the same width or smaller than the connection portion 1750 of the inner case 1700. Each end of the "+ wire" and the "-wire" may be electrically connected to the extension 1670, and the other end of the "+ wire" and the "-wire" may be electrically connected to the socket 1800. .

The inner case 1700 may include a molding unit together with the power supply unit 1600 therein. The molding part is a part where the molding liquid is hardened, so that the power supply 1600 can be fixed inside the inner case 1700.

9 illustrates a display device including a light emitting device according to an exemplary embodiment.

9, the display device 800 includes a bottom cover 810, a reflector 820 disposed on the bottom cover 810, light emitting modules 830 and 835 that emit light, and a reflector 820. ) An optical sheet including a light guide plate 840 disposed in front of the light guide plate and guiding light emitted from the light emitting modules 830 and 835 to the front of the display device, and prism sheets 850 and 860 disposed in front of the light guide plate 840. A display panel 870 disposed in front of the optical sheet, an image signal output circuit 872 connected to the display panel 870 and supplying an image signal to the display panel 870, and disposed in front of the display panel 870. The color filter 880 may be included. The bottom cover 810, the reflector 820, the light emitting modules 830 and 835, the light guide plate 840, and the optical sheet may form a backlight unit.

The light emitting module may include light emitting device packages 835 mounted on the substrate 830. Here, the substrate 830 may be a PCB or the like. The light emitting device package 835 may be the embodiment shown in FIG. 7.

The bottom cover 810 may accommodate components in the display device 800. In addition, the reflective plate 820 may be provided as a separate component as shown in the drawing, or may be provided in the form of a high reflective material on the rear surface of the light guide plate 840 or the front surface of the bottom cover 810. .

Here, the reflective plate 820 may use a material having a high reflectance and being extremely thin, and may use polyethylene terephthalate (PET).

The light guide plate 830 may be formed of polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), or the like.

In addition, the first prism sheet 850 may be formed of a light transmitting and elastic polymer material on one surface of the support film, and the polymer may have a prism layer in which a plurality of three-dimensional structures are repeatedly formed. Here, the plurality of patterns may be provided in the stripe type and the valley repeatedly as shown.

In addition, the direction of the floor and the valley of one surface of the support film in the second prism sheet 860 may be perpendicular to the direction of the floor and the valley of one surface of the support film in the first prism sheet 850.

This is to evenly distribute the light transmitted from the light emitting module and the reflective sheet to the front surface of the display panel 1870.

Although not shown, a diffusion sheet may be disposed between the light guide plate 840 and the first prism sheet 850. The diffusion sheet may be made of a polyester and polycarbonate-based material, and may maximize the light projection angle through refraction and scattering of light incident from the backlight unit. The diffusion sheet is formed on a support layer including a light diffusing agent, a first layer and a second layer which are formed on a light exit surface (first prism sheet direction) and a light incident surface (reflective sheet direction) and do not include a light diffusing agent. It may include.

In an embodiment, the diffusion sheet, the first prism sheet 850, and the second prism sheet 860 form an optical sheet, which optical sheet is formed of another combination, for example, a micro lens array or a diffusion sheet and a micro lens array. Or a combination of one prism sheet and a micro lens array.

A liquid crystal display panel may be disposed on the display panel 870. In addition to the liquid crystal display panel 860, another type of display device that requires a light source may be provided.

Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in each embodiment may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be interpreted that the contents related to such a combination and modification are included in the scope of the present invention.

100 substrate 115 buffer layer
120: light emitting structure 122: first conductive semiconductor layer
124: active layer 125: carrier injection layer
126: electron blocking layer 127: second conductivity type semiconductor layer
130: conductive layer 142: first electrode
144: second electrode QW1 to QWn: well layer
QB1 to QBn: barrier layer.

Claims (5)

A first conductivity type semiconductor layer;
A second conductive semiconductor layer disposed on the first conductive semiconductor layer;
An active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer, the active layer including well layers and barrier layers; And
A carrier injection layer disposed between the active layer and the second conductive semiconductor layer and doped with a second conductive dopant,
The energy band gap of the carrier injection layer decreases from the active layer toward the second conductive semiconductor layer,
The carrier injection layer is spaced apart from the well layers,
The last barrier layer closest to the second conductivity type semiconductor layer among the barrier layers is in contact with the last well layer closest to the second conductivity type semiconductor layer among the carrier injection layer and the well layers,
The thickness of the last barrier layer is thicker than the thickness of each of the barrier layers except for the last barrier layer among the barrier layers,
The last barrier layer is
A first portion in contact with the last well layer;
A third portion in contact with the carrier injection layer; And
A second portion located between the first portion and the third portion,
The energy band gap of the second portion is greater than the energy band gap of each of the remaining barrier layers,
The second portion comprises aluminum,
An energy band gap of the second portion is greater than an energy band gap of each of the first portion and the third portion,
The energy band gap of the second portion is uniform, or gradually increases or decreases gradually from the active layer toward the second conductive semiconductor layer. delete delete delete delete

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