KR101874904B1 - A light emitting device - Google Patents

Abstract

An embodiment includes a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer and having a well layer and a barrier layer stacked alternately at least once, Wherein the well layer includes a first section in which the energy band decreases in the first direction and a second section in which the energy band increases in the first direction, And the first direction is a direction from the first semiconductor layer to the second semiconductor layer.

Description

A light emitting device

The present invention relates to a light emitting device and a light emitting device package.

Light emitting devices such as light emitting diodes and laser diodes using semiconductor materials of Group 3-5 or Group 2-6 compound semiconductors can realize various colors such as red, green, blue and ultraviolet rays through the development of thin film growth techniques and device materials, By using fluorescent materials or by combining colors, it is possible to realize a white light beam having high efficiency.

With the development of such technology, not only display devices but also transmission modules of optical communication means, light-emitting diode backlights replacing CCFL (Cold Cathode Fluorescence Lamp) constituting the backlight of LCD (Liquid Crystal Display) White light emitting diodes (LED) lighting devices, automotive headlights, and traffic lights. For the structure of such a light-emitting device, reference may be made to US Pat.

Embodiments provide a light emitting device capable of improving internal quantum efficiency.

A light emitting device according to an embodiment includes a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer and having a well layer and a barrier layer stacked alternately at least once Wherein the well layer includes a first section in which the energy band decreases in the first direction and a second section in which the energy band increases in the first direction, And the first direction is a direction from the first semiconductor layer to the second semiconductor layer. The first section and the second section may be adjacent to each other.

The slope of the energy band of each of the sub-sections of the first section linearly decreases and the slope of the energy band of the second section may linearly increase. The slopes of the energy bands of the sub-sections may be different from each other.

The first semiconductor layer may be an n-type semiconductor layer, and the second semiconductor layer may be a p-type semiconductor layer. The first semiconductor layer may be a p-type semiconductor layer, and the second semiconductor layer may be an n-type semiconductor layer.

The barrier layer is _{Al a In b GaN (1-} ab) having a composition of (0≤a <1, 0 <b <1), the well layer is _{In x GaN (1-x)} (0 <x <1) . &Lt; / RTI &gt; The content of indium (In) in each of the first sub-section and the second sub-section may increase linearly. The indium (In) content in the second section may decrease linearly. The composition of the two or more of the sub-section a first sub-interval is _{In x GaN (1-x)} (0 <x≤0.13) , and the second composition of the sub-interval is _{In x GaN (1-x)} (0.13≤x Lt; = 0.17). The composition of the second section may be In _x GaN _(1-x) (0.17? X <1). The ratio of the thickness of the second section to the thickness of the first section may be 1: 1.5 to 2.5. The thicknesses of the sub-sections may be equal to each other.

The light emitting device includes a substrate disposed below the first semiconductor layer, a conductive layer disposed on the second semiconductor layer, a first electrode disposed on the first semiconductor layer, and a second electrode disposed on the conductive layer, Electrode.

Alternatively, the light emitting device may further include a first electrode disposed on the first semiconductor layer, an ohmic layer disposed under the second semiconductor layer, and a reflective layer disposed under the ohmic layer.

The embodiment can compensate for the shift of the energy band in the active layer due to the piezoelectric field and improve the internal quantum efficiency.

1 shows a light emitting device according to an embodiment.
2 shows the energy band of the conduction band of the active layer according to the embodiment.
3 shows the energy band of the conduction band of the active layer according to another embodiment.
Figure 4 shows an energy band diagram of a generally grown active layer.
5 shows an energy band diagram of an active layer of a light emitting device according to an embodiment.
6 shows the internal quantum efficiency of the light emitting device according to the embodiment.
7 shows a light emitting device according to another embodiment.
8 illustrates a light emitting device package including a light emitting device according to an embodiment.
9 is an exploded perspective view of a lighting device including a light emitting device package according to an embodiment.
10 shows a display device including a light emitting device package according to an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the drawings, dimensions are exaggerated, omitted, or schematically illustrated for convenience and clarity of illustration. Also, the size of each component does not entirely reflect the actual size. The same reference numerals denote the same elements throughout the description of the drawings. Hereinafter, a light emitting device and a light emitting device package according to embodiments will be described with reference to the accompanying drawings.

1 shows a light emitting device 100 according to an embodiment. Referring to FIG. 1, a light emitting device 100 includes a substrate 110, a light emitting structure 120, a conductive layer 125, a first electrode 130, and a second electrode 140.

The substrate 110 may be formed of a carrier wafer, a material suitable for semiconductor material growth. Further, the substrate 110 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. For example, the substrate 110 may be a material comprising at least one of sapphire (Al ₂ O ₃ ), GaN, SiC, ZnO, Si, GaP, InP, Ga ₂ O ₃ , GaAs. An irregular pattern may be formed on the upper surface of the substrate 110. The substrate 110 may be disposed below the light emitting structure (e.g., the first conductivity type semiconductor layer 122).

The light emitting structure 120 may be a semiconductor layer that generates light and may include a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126. The light emitting structure 120 may have a structure in which a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 are sequentially stacked on a substrate 110. Where the first conductivity type may be n-type and the second conductivity type may be p-type. Although not shown in the drawing, at least one buffer layer (buffer layer) is formed between the first conductive semiconductor layer 122 and the substrate 110 to mitigate lattice mismatch between the substrate 110 and the semiconductor layer 120 due to lattice mismatching. layer may be formed.

The first conductive semiconductor layer 122 may be formed of a semiconductor compound. The first conductive semiconductor layer 122 may be formed of a compound semiconductor such as a group III-V element, a group II-VI element, or the like, and the first conductive type dopant may be doped.

For example, the first conductivity type semiconductor layer 122 may be a semiconductor semiconductor having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + . For example, the first conductive semiconductor layer 122 may include any one of InAlGaN, GaN, AlGaN, InGaN, AlN, and InN, and may be doped with an n-type dopant such as Si, Ge, .

The active layer 124 is disposed between the first conductivity type semiconductor layer 122 and the second conductivity type semiconductor layer 126 and is provided from the first conductivity type semiconductor layer 122 and the second conductivity type semiconductor layer 126 Light can be generated by the energy generated in the recombination process of electrons and holes.

The active layer 124 may be a compound semiconductor of a semiconductor compound such as a Group 3-V-5 or a Group 2-VI-6 compound semiconductor and may be a single well structure, a multi-well structure, a Quantum-Wire structure, Dot) structure or the like.

The active layer 124 is a multi-layer structure in which at least one or more well layers 19-1 to 19-M and a plurality of barrier layers 19-1 to 19- (natural numbers of N> 1) are alternately stacked . The well layers 19-1 through 19-M, natural numbers M> 1 may be a quantum well layer, and the barrier layers 18-1 through 18-N may be a quantum barrier layer.

The second conductive semiconductor layer 126 may be formed of a semiconductor compound. The second conductive semiconductor layer 126 may be formed of a compound semiconductor such as Group 3-Group 5, Group 2-Group 6, or the like, and may be doped with a second conductive type dopant.

For example, the second conductivity type semiconductor layer 126 may be a semiconductor semiconductor having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + . For example, the second conductive semiconductor layer 126 may include any one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. , Mg, Zn, Ca, Sr, Ba) can be doped.

2 shows the energy band of the conduction band of the active layer 124 according to the embodiment. Referring to FIG. 2, each of the well layers 19-1 to 19-M includes a first section a1 in which the potential of the energy band is decreased and a second section a2 in which the potential of the energy band is increased do.

The first section a1 and the second section a2 are in contact with each other so that the potential of the energy band decreases in the first direction a1 and the potential of the energy band in the first direction a2 decreases. Can be increased. In this case, the first direction may be a direction from the first conductivity type semiconductor layer 122 to the second conductivity type semiconductor layer 126.

The first section a1 may include two or more sub-sections b1 and b2 that decrease at different slopes. In each of the two or more sub-intervals b1 and b2, the potential of the energy band may decrease linearly, but is not limited thereto, and may be nonlinearly or systematically decreased.

In the second section a2, the potential of the energy band may increase linearly, but it is not limited thereto, and may be nonlinearly or gradually increased. The absolute value of the slope of each of the sub-intervals b1 and b2 may be smaller than the absolute value of the slope of the second interval a2.

The composition of the well layers 19-1 to 19-M, for example, M = 3 may be In _x GaN _(1-x) (0 <x <1).

The composition of the barrier layers 18-1 to 18-N, for example, N = 2 may be Al _a In _b GaN _(1-ab) (0? A <1, 0 <b <1). For example, the barrier layers 18-1 to 18-N (e.g., N = 2) may have a larger bandgap energy than that of the well layers 19-1 to 19-M ) N-type group III nitride semiconductor layer, for example, an AlGaN layer, an InGaN layer, or a GaN layer.

The composition of indium (In) in the first section a1 may gradually increase. For example, the composition of indium (In) in the first section a1 may increase linearly. For example, the content of indium (In) in each of the sub-regions b1 and b2 may increase linearly.

Also, the growth rates of indium (In) in the sub-regions b1 and b2 may be different from each other. For example, the rate of increase of indium in the first sub-section b1 may be larger or smaller than the rate of increase of indium in the second sub-interval b2.

The composition of the first sub-section b1 may be In _x GaN _(1-x) (0 < _x ? 0.13) and the composition of the second sub-section b2 may be In _x GaN _(1-x) x? 0.17).

The composition of indium in the second section a2 may gradually decrease. For example, the composition of indium in the second section a2 may decrease linearly. The composition of the second section a2 may be In _x GaN _(1-x) (0.17? X <1).

The thickness of each of the well layers 19-1 to 19-M, e.g., M = 3, may be 1.5 nm to 3 nm. The ratio of the thickness of the second section a2 to the thickness of the first section a1 may be 1: 1.5 to 2.5. For example, the thickness of the first section a1 may be 2 nm or less, and the thickness of the second section a2 may be 1 nm or less.

The thicknesses of the sub-sections b1 and b2 may be equal to each other. The thickness of each of the barrier layers 18-1 through 18-N, e.g., N = 2, may be between 5 nm and 30 nm.

In general, when an electric field is applied perpendicularly to the quantum well structure, the wave functions of the electon and hole in the ground state can move in different traveling directions. In other words, the subband energy of the electrons moves down, and the subband energy of holes moves upwards.

This reduces the binding energy of the excitons, that is, the electron-hole pairs, and the band gap energy can be reduced. This phenomenon is referred to as a quantum confined stark effect (QCSE).

Generally, during the growth of an active layer including a quantum well layer (InGaN) and a quantum barrier layer (GaN), a stress occurs at the interface between the InGaN layer and the GaN layer due to lattice mismatch between InGaN and GaN , And this stress can cause a piezoelectric field itself. The quantum confinement stark effect is generated by the piezoelectric field, and the internal quantum efficiency (IQE) of the light emitting device can be reduced.

Figure 4 shows an energy band diagram of a generally grown active layer. f1 represents the wave function of the electron, f2 represents the wave function of the hole, g1 represents the energy band of electrons, and g2 represents the energy band of holes.

 Referring to FIG. 4, the energy band of the grown active layer may be bent by the piezoelectric field (401, 402). As a result, the overlap of the electron wave function f1 and the hole wave function f2 is reduced and the internal quantum efficiency can be reduced.

However, as shown in FIG. 2, the embodiment includes the well layers 19-1 to 19-M or 19 having the energy bands of the type capable of compensating the energy band which is deformed by the piezoelectric field when the active layer 124 is grown, -1 to 19-M '). That is, the embodiment can compensate the energy band which is deformed by the piezoelectric field by controlling the composition of indium contained in the well layers 19-1 to 19-M, or 19-1 to 19-M '.

As the well layer is grown by controlling the indium composition so as to have a shape as shown in FIG. 2, the energy band that is deformed by the piezoelectric field is compensated, so that a flat energy band can be formed.

The embodiment can compensate for the shift of the energy band in the active layer 124 due to the piezoelectric field, thereby preventing the deformation of the energy band and improving the internal quantum efficiency of the light emitting device 100. [

5 shows an energy band diagram of an active layer of a light emitting device according to an embodiment. Referring to FIG. 5, the active layer 124 of the embodiment can have a flat energy band 501, 502 compensating for the deformation of the energy band due to the piezoelectric field.

6 shows the internal quantum efficiency of the light emitting device according to the embodiment.

The x axis represents the current density (A / cm 2) applied to the light emitting element, and the y axis represents the internal quantum efficiency. R is the energy band of the well layer is rectangular, T is the energy band of the well layer is trapezoidal, E1 is the energy band of the well layer according to the embodiment shown in FIG. 2 And E2 is the case where the energy band of the well layer is according to the embodiment shown in Fig.

Referring to FIG. 6, it can be seen that the internal quantum efficiency is improved by the cases (E1, E2) according to the embodiment, as compared with the other cases (R, T).

3 shows the energy band of the conduction band of the active layer 124 according to another embodiment. Referring to FIG. 3, each of the well layers 19-1 'to 19-M' and M '> 1 has a first section a1' in which the potential of the energy band is decreased, And a second section a2 'that increases.

The first section a1 'and the second section a2' are in contact with each other and the potential of the energy band in the first section a1 'decreases in the first direction and the potential of the energy band decreases in the first section a2' The potential of the energy band can be increased. In this case, the first direction may be a direction from the first conductivity type semiconductor layer 122 to the second conductivity type semiconductor layer 126.

The potential of the energy band of the first section a1 'may decrease linearly, but is not limited thereto, and may be nonlinearly or systematically reduced.

The second section a2 'may include two or more sub-sections b1', b2 'that increase in different slopes. In each of the two or more sub-intervals b1 'and b2', the potential of the energy band may increase linearly, but is not limited thereto, and may increase non-linearly or continuously.

The absolute value of the slope of the potential of the energy band of each of the sub-sections b1 'and b2' may be smaller than the absolute value of the slope of the energy band potential of the first section a1 '.

The composition of the well layers 19-1 'to 19-M', for example, M '= 3 may be In _y GaN _(1-y) (0 <x <1). The barrier layers 18-1 'to 18-N', e.g., N '= 2, have a bandgap energy greater than that of the well layers 19-1' to 19-M ' , In, Ga) N series, for example, an AlGaN layer, an InGaN layer, or a GaN layer.

The composition of indium in the first section a1 'may gradually increase. For example, the composition of indium in the first section a1 'may increase linearly. The composition of the first section a1 'may be In _y GaN _(1-y) (1 < _y ? 0.17).

The indium composition of the second section a2 'may gradually decrease. for example. The indium composition of the second section a2 'may decrease linearly. For example, the content of indium (In) in each of the sub-regions b1 'and b2' may be linearly decreased.

Also, the decreasing rates of indium (In) in the sub-regions b1 'and b2' may be different from each other. For example, the decreasing rate of indium in the first sub-section b1 'may be larger or smaller than the decreasing rate of indium in the second sub-section b2'.

The composition of the first sub-section b1 'may be In _y GaN _(1-y) (0.17 _x 0.13), and the composition of the second sub-section b2' may be In _y GaN _(1-y) 0.13? X? 1).

The thickness of each of the well layers 19-1 'to 19-M', e.g., M '= 3, may be 1.5 nm to 3 nm. The ratio of the thickness of the first section a1 'to the thickness of the second section a2' may be 1: 1.5 to 2.5. For example, the thickness of the first section a1 'may be 1 nm or less, and the thickness of the second section a2' may be 2 nm or less. The thicknesses of the sub-sections b1 'and b2' may be equal to each other. The thickness of each of the barrier layers 18-1 'to 18-N', e.g., N '= 2, may be between 5 nm and 30 nm.

The light emitting structure 120 may include a structure in which the second conductive semiconductor layer 126, the active layer 120, and a portion of the first conductive semiconductor layer 122 are etched to expose a part of the first conductive semiconductor layer 122 Lt; / RTI &gt;

The conductive layer 125 is disposed on the second conductive type semiconductor layer 126. The conductive layer 125 not only reduces the total reflection but also increases light extraction efficiency of the light emitted from the active layer 124 to the second conductivity type semiconductor layer 126 because of its good translucency.

The conductive layer 125 may be formed of a transparent oxide material having a high transmittance with respect to an emission wavelength such as ITO (Indium Tin Oxide), TO (Tin Oxide), IZO (Indium Zinc Oxide), IZTO (Indium Zinc Tin Oxide) Indium Gallium Zinc Oxide (IGZO), IGTO (Indium Gallium Tin Oxide), AZO (Aluminum Tin Oxide), ATO (Aluminum Tin Oxide), GZO (Gallium Zinc Oxide), IrOx, RuOx, RuOx / ITO , Ni, Ag, Ni / IrOx / Au or Ni / IrOx / Au / ITO.

The first electrode 130 may be disposed on the first conductive semiconductor layer 122 exposed by etching and the second electrode 140 may be disposed on the conductive layer 125. The first electrode 130 and the second electrode 140 may be formed of a conductive metal such as Cr, Ni, Au, Al, Ti, One or an alloy thereof.

7 shows a light emitting device 200 according to another embodiment. Referring to FIG. 7, the light emitting device 200 includes a second electrode layer 205, a light emitting structure 120, a passivation layer 235, a passivation layer 250, and a first electrode 260 .

The second electrode layer 205 supports the light emitting structure 120 and supplies a second power.

The second electrode layer 205 may include a support layer 210, a bonding layer 215, a barrier layer 220, a reflective layer 225, and an ohmic contact layer 230.

The support layer 210 may be made of a metal substrate or a semiconductor. For example, the support layer 210 may be formed of a metal material such as Cu, Cr, Ni, Ag, Au, Mo, Pd, W, or Al.

The barrier layer 220 is disposed between the light emitting structure 120 and the support layer 210 and prevents metal ions of the support layer 210 from diffusing into the light emitting structure 120. The barrier layer 220 may be made of a barrier metal material, such as nickel (Ni), titanium (Ti), or TiN.

The bonding layer 215 may be disposed between the barrier layer 220 and the support layer 210. The bonding layer 215 may be interposed between the barrier layer 220 and the supporting layer 210 to bond them together.

The bonding layer 215 is formed to bond the supporting layer 210 by bonding. Therefore, when the supporting layer 210 is formed by plating or vapor deposition or when the supporting layer 210 is a semiconductor layer, Can be omitted. The bonding layer 215 may include at least one of a bonding metal material such as Au, Sn, Ni, Nb, In, Cu, Ag, and Pd.

The reflective layer 225 is disposed on the barrier layer 220 to improve the effective luminance and may be formed of a reflective material such as Au, Ni, Ag, Al, or an alloy thereof.

The ohmic layer 230 is positioned between the reflective layer 225 and the second conductive semiconductor layer 220 for ohmic contact between the reflective layer 225 and the light emitting structure 120. The ohmic layer 230 may be formed of a material that makes an ohmic contact with the second conductive semiconductor layer 220 such as ITO (Indium Tin Oxide), TO (Tin Oxide), IZO (Indium Zinc Oxide), IZTO (Indium Zinc Tin Oxide) (Indium Gallium Tin Oxide), IGTO (Indium Gallium Tin Oxide), AZO (Aluminum Tin Oxide), ATO (Aluminum Tin Oxide), GZO (Gallium Zinc Oxide), IrOx, RuOx, And a transparent conductive oxide containing at least one of RuOx / ITO, Ni, Ag, Ni / IrOx / Au, or Ni / IrOx / Au / ITO.

The light emitting structure 120 is disposed on the second electrode layer 205. For example, the light emitting structure 120 may include a second conductive semiconductor layer 126, an active layer 124, and a first conductive semiconductor layer 122 that are sequentially stacked on the second electrode layer 205 . The active layer 124 may include at least once alternating well layers 19-1 through 19-M and barrier layers 18-1 through 18-N. The potential, composition, thickness, etc. of the energy bands of the well layers 19-1 to 19-M and the barrier layers 18-1 to 18-N may be the same as those described above.

The protective layer 235 may be disposed on the edge region of the second electrode layer 205. For example, the protective layer 235 may be disposed on the edge region of the barrier layer 220 adjacent to the side surface of the light emitting structure 120, and one side may be adjacent to the ohmic layer 215.

The passivation layer 250 may be disposed on the top surface or side of the light emitting structure 120 to protect the light emitting structure 120. The passivation layer 235 or the passivation layer 250 may be formed of a silicon oxide film (SiO ₂ ), a silicon nitride film (Si ₃ N ₄ ), or AlN. The first electrode 260 may be disposed on the first conductive semiconductor layer 146.

As described above, the embodiment can compensate the deviation of the energy band in the active layer 124 due to the piezoelectric electric field, thereby preventing the deformation of the energy band and improving the internal quantum efficiency of the light emitting element 200. [

8 illustrates a light emitting device package including a light emitting device according to an embodiment.

Referring to FIG. 8, a light emitting device package according to an embodiment includes a package body 510, a first lead frame 512, a second lead frame 514, a light emitting device 520, a reflection plate 525, ), And a resin layer 540.

The package body 510 is a structure in which a cavity is formed in one side region. At this time, the side wall of the cavity may be formed to be inclined. The package body 510 may be formed of a substrate having good insulating or thermal conductivity, such as a silicon based wafer level package, a silicon substrate, silicon carbide (SiC), aluminum nitride (AlN) Or may be a structure in which a plurality of substrates are stacked. The embodiments are not limited to the material, structure, and shape of the body described above.

The first lead frame 512 and the second lead frame 514 may be disposed on the surface of the package body 510 so as to be electrically separated from each other in consideration of heat discharge or mounting of the light emitting device. The light emitting device 520 is electrically connected to the first lead frame 512 and the second lead frame 514. Here, the light emitting device 520 may be any one of the light emitting devices 100, 200, and 300 according to the embodiment.

For example, the first electrode 130 of the light emitting device 100 shown in FIG. 1 is electrically connected to the second lead frame 514 by the second wire 524. The second electrode 140 may be electrically connected to the first lead frame 512 by the first wire 522.

The second electrode portion 205 of the light emitting device 200 shown in FIG. 7 may be bonded to the first lead frame 512 and the first electrode 260 may be electrically connected to the second lead frame 514 have.

The reflection plate 525 is formed on the cavity side wall of the package body 510 so as to direct the light emitted from the light emitting element 520 in a predetermined direction. The reflection plate 525 is made of a light reflection material, and may be, for example, a metal coating or a metal flake.

The resin layer 540 surrounds the light emitting element 520 located in the cavity of the package body 510 to protect the light emitting element 520 from the external environment. The resin layer 540 is made of a colorless transparent polymer resin material such as epoxy or silicone. The resin layer 540 may include a phosphor to change the wavelength of light emitted from the light emitting device 520. The light emitting device package can mount at least one of the light emitting elements of the above-described embodiments, but is not limited thereto.

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

Still another embodiment may be implemented as a display device, an indicating device, and a lighting system including the light emitting device or the light emitting device package described in the above embodiments. For example, the lighting system may include a lamp and a streetlight.

9 is an exploded perspective view of a lighting device including a light emitting device package according to an embodiment. 9, the illumination device includes a light source 750 for projecting light, a housing 700 having a light source 7500, a heat dissipation unit 740 for emitting heat of the light source 750, a light source 750, And a holder 760 that couples the heat dissipating portion 740 to the housing 700.

The housing 700 includes a socket coupling portion 710 coupled to an electric socket (not shown), and a body portion 730 connected to the socket coupling portion 710 and having a light source 750 embedded therein. One air flow hole 720 may be formed through the body portion 730.

A plurality of air flow holes 720 are provided on the body portion 730 of the housing 700 and one or more air flow holes 720 may be provided. The air flow port 720 may be disposed radially or in various forms on the body portion 730.

The light source 750 includes a plurality of light emitting device packages 752 provided on the substrate 754. [ The substrate 754 may have a shape that can be inserted into the opening of the housing 700 and may be made of a material having a high thermal conductivity to transmit heat to the heat dissipating unit 740 as described later. The plurality of light emitting device packages may be the above-described embodiments.

A holder 760 is provided below the light source 750, and the holder 760 may include a frame and other air flow holes. Although not shown, an optical member may be provided under the light source 750 to diffuse, scatter, or converge light projected from the light emitting device package 752 of the light source 750.

10 shows a display device including a light emitting device package according to an embodiment. 10, the display device 800 includes a bottom cover 810, a reflection plate 820 disposed on the bottom cover 810, light emitting modules 830 and 835 for emitting light, a reflection plate 820 A light guide plate 840 disposed in front of the light emitting module 830 and guiding the 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, An image signal output circuit 872 connected to the display panel 870 and supplying an image signal to the display panel 870 and a display panel 870 disposed in front of the display panel 870, And a color filter 880 disposed therein. Here, the bottom cover 810, the reflection plate 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 comprises a light emitting device package 835 on a substrate 830. The substrate 830 may be a PCB or the like. The light emitting device package 835 may be a light emitting device package according to the embodiment.

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

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

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

The first prism sheet 850 may be formed of a light-transmissive and elastic polymeric material on one side of the support film, and the polymer may have a prism layer in which a plurality of three-dimensional structures are repeatedly formed. Here, as shown in the drawings, the plurality of patterns may be provided with a floor and a valley repeatedly as stripes.

In the second prism sheet 860, the direction of the floor and the valley on one side of the supporting film may be perpendicular to the direction of the floor and the valley on one side of the supporting film in the first prism sheet 850. This is for evenly distributing 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 polyester and polycarbonate-based materials, and the light incidence angle can be maximized by refracting and scattering light incident from the backlight unit. The diffusion sheet includes a support layer including a light diffusing agent, a first layer formed on the light exit surface (first prism sheet direction) and a light incidence surface (in the direction of the reflection sheet) . &Lt; / RTI &gt;

In an embodiment, the diffusion sheet, the first prism sheet 850, and the second prism sheet 1860 make up an optical sheet, which may be made of other combinations, for example a microlens array, A combination of one prism sheet and a microlens array, or the like.

The display panel 870 may include a liquid crystal display (LCD) panel, and may include other types of display devices that require a light source in addition to the liquid crystal display panel 860.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments can be combined and modified by other persons having ordinary skill in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

110: substrate, 120: light emitting structure,
122: first conductivity type semiconductor layer, 124: active layer
125: conductive layer, 126: second conductive type semiconductor layer,
130: first electrode, 140: second electrode
205: second electrode layer, 210: support layer
220: barrier layer, 225: reflective layer
230: ohmic layer, 235: protective layer
250: passivation layer, 260: first electrode
18-1 to 18-N: barrier layer, 19-1 to 19-M: well layer.

Claims (15)

A first semiconductor layer;
A second semiconductor layer; And
And an active layer disposed between the first semiconductor layer and the second semiconductor layer and having a well layer and a barrier layer stacked alternately at least once,
Wherein the well layer comprises:
A first section in which an energy band decreases in a first direction; And
And a second section in contact with the first section and linearly increasing an energy band in the first direction,
The first section
A first sub-section having a slope of a linearly decreasing first energy band; And
And a second sub-section having a slope of a linearly decreasing second energy band,
Wherein a slope of the first energy band and a slope of the second energy band are different from each other,
The ratio of the thickness of the second section to the thickness of the first section is 1: 1.5 to 2.5,
The absolute value of each of the slopes of the first and second energy bands is smaller than the absolute value of the slope of the energy band of the second section,
Wherein the first direction is a direction from the first semiconductor layer to the second semiconductor layer. delete delete delete The method according to claim 1,
Wherein the first semiconductor layer is an n-type semiconductor layer and the second semiconductor layer is a p-type semiconductor layer. The method according to claim 1,
The first semiconductor layer is a p-type semiconductor layer, and the second semiconductor layer is an n-type semiconductor layer. The method according to claim 1,
Wherein the composition of the first sub-section is In _x GaN _(1-x) (0 < _x ? 0.13), the composition of the second sub-section is In _x GaN _(1-x) The composition of the second section is In _x GaN _(1-x) (0.17? X <1)
The content of indium in each of the first and second sub-sections in the first direction linearly increases,
And the indium content in the second section in the first direction decreases linearly. delete delete delete delete delete The method according to claim 1,
Wherein the first and second sub-sections have the same thickness. A package body;
A first lead frame and a second lead frame disposed in the package body;
A light emitting element electrically connected to the first lead frame and the second lead frame, the light emitting element according to any one of claims 1 to 7, and 13; And
And a resin layer surrounding the light emitting element. delete

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