KR20140099646A - A light emitting device - Google Patents

Abstract

An embodiment of the present invention includes a first semiconductor layer, an active layer which is arranged under the first semiconductor layer, and a second semiconductor layer which is arranged under the active layer. The energy band-gap of the first semiconductor layer increases in a first direction and the energy band-gap of the second semiconductor layer decreases in the first direction. The first direction is from the first semiconductor layer to the second semiconductor layer.

Description

A LIGHT EMITTING DEVICE

An embodiment relates to a light emitting element.

2. Description of the Related Art Generally, a light emitting diode (LED) converts an electric signal into an infrared ray, a visible ray, or a light by using a compound semiconductor characteristic of recombination of electrons and holes. Semiconductor device.

In the LED, the frequency (or wavelength) of the emitted light is a function of the band gap of the semiconductor material. When a semiconductor material having a small band gap is used, photons of low energy and long wavelength are generated, When a semiconductor material having a bandgap is used, short wavelength photons are generated. Therefore, the semiconductor material of the device is selected depending on the type of light to be emitted.

It is important to increase light extraction efficiency to realize LED high brightness. In order to increase the light extraction efficiency, a flip-chip structure, surface texturing, patterned sapphire substrate (PSS), photonic crystal technology, and anti-reflection layer structure is being studied.

In general, a light emitting device includes a light emitting structure that is a semiconductor layer that generates light, a first electrode and a second electrode to which power is supplied, a current blocking layer for current dispersion, an ohmic layer that is in ohmic contact with the light emitting structure, And an ITO (Indium Tin Oxide) layer for improving light extraction efficiency.

The embodiment provides a light-emitting element capable of securing high-quality crystallinity, improving luminous efficiency, and preventing deterioration of electrical characteristics.

A light emitting device according to an embodiment includes a first semiconductor layer; An active layer disposed under the first semiconductor layer; And a second semiconductor layer disposed under the active layer, wherein an energy band gap of the first semiconductor layer increases as the first semiconductor layer progresses in a first direction, and an energy band gap of the second semiconductor layer progresses in the first direction And the first direction is a direction from the first semiconductor layer to the second semiconductor layer.

Wherein the composition formula of the first semiconductor layer is Al _y Ga _{1 -y} N (0 <y <1), the composition formula of the second semiconductor layer is Al _x Ga _{1 -x} N (0 <x <1) The Al content ratio of the first semiconductor layer may increase as the first semiconductor layer progresses in the first direction and the Al content ratio of the second semiconductor layer may decrease as the semiconductor layer progresses in the first direction.

The content ratio of Al in the first semiconductor layer may increase linearly and the content ratio of Al in the second semiconductor layer may decrease linearly.

The Al content ratio of the first semiconductor layer can be gradually increased and the content ratio of Al in the second semiconductor layer can be reduced in a stepwise manner.

The first semiconductor layer may include a plurality of first layers, and the content ratio of Al in the plurality of first layers may increase in the first direction.

The second semiconductor layer may include a plurality of second layers, and the content ratio of Al in the plurality of second layers may decrease in the first direction.

The first semiconductor layer is disposed between adjacent two first layers, may further include a third layer having a composition formula of _{Al a Ga 1 -a N (0≤a} <1). The content ratio of Al in the third layer may be smaller than the content ratio of Al in the first layers.

The second semiconductor layer may further include a fourth layer disposed between adjacent two second layers and having a composition formula of Al _b Ga _{1 -b} N (0? B <1). The content ratio of Al in the fourth layer may be smaller than the content ratio of Al in the second layers.

The first layers and the third layer may have a superlattice structure, and the second layers and the fourth layer may have a superlattice structure.

The energy band gap of the first semiconductor layer may increase linearly and the energy band gap of the second semiconductor layer may decrease linearly.

The energy band gap of the first semiconductor layer can be gradually increased and the energy band gap of the second semiconductor layer can be reduced in a stepwise manner.

The light emitting device comprising: a first electrode disposed on the first semiconductor layer; A reflective layer disposed below the second semiconductor layer; An ohmic region disposed between the second semiconductor layer and the reflective layer; And a support layer disposed under the reflective layer.

The active layer may emit light having a wavelength of 250 nm to 390 nm.

The embodiment can prevent the deterioration of the electrical characteristics, the improvement of the light emitting efficiency, and the ensuring of the high quality of crystallinity.

1 is a cross-sectional view of a light emitting device according to an embodiment.
Fig. 2 shows an energy band gap according to the first embodiment of the light emitting structure shown in Fig.
FIG. 3A shows a content ratio of Al in the first semiconductor layer of FIG. 2. FIG.
FIG. 3B shows a content ratio of Al in the second semiconductor layer of FIG. 2. FIG.
4 shows a cross-sectional view of a light emitting structure according to the second embodiment.
Fig. 5 shows the energy band gap of the first semiconductor layer and the second semiconductor layer in Fig.
6A shows a content ratio of Al in the first semiconductor layer of FIG.
FIG. 6B shows the content ratio of Al in the second semiconductor layer of FIG. 4; FIG.
7 is a cross-sectional view of a light emitting structure according to the third embodiment.
8 shows the energy band gap of the first semiconductor layer and the second semiconductor layer in Fig.
FIG. 9A shows a content ratio of Al in the first semiconductor layer in FIG.
FIG. 9B shows a content ratio of Al in the second semiconductor layer in FIG. 7. FIG.
10 is a sectional view of a light emitting device according to another embodiment.
11 shows a light emitting device package according to an embodiment.
12 is an exploded perspective view of a lighting device including a light emitting device package according to an embodiment.
13 shows a display device including the light emitting device package according to the embodiment.
14 shows a head lamp including the light emitting device package according to the 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 description of the embodiments, it is to be understood that each layer (film), region, pattern or structure may be referred to as being "on" or "under" a substrate, each layer It is to be understood that the terms " on "and " under" include both " directly "or" indirectly " do. In addition, the criteria for the top / bottom or bottom / bottom of each layer are described with reference to the drawings.

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 according to an embodiment will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a light emitting device 100 according to an embodiment.

Referring to FIG. 1, the light emitting device 100 includes a second electrode 105, a passivation layer 140, a current blocking layer 145, a light emitting structure 150, a passivation layer 165, One electrode 170 is formed.

The second electrode 105 provides power to the light emitting structure 150 together with the first electrode 170. The second electrode 105 includes a support 110, a bonding layer 115, a barrier layer 120, a reflective layer 125, and an ohmic region 130 .

The support layer 110 may support the light emitting structure 150. The support layer 110 may be formed of a metal or a semiconductor material. The support layer 110 may also be formed of a material having high electrical conductivity and high thermal conductivity.

For example, the support layer 110 may be formed of a metal containing at least one of copper (Cu), a copper alloy, gold (Au), nickel (Ni), molybdenum (Mo), and copper- Material, or a semiconductor including at least one of Si, Ge, GaAs, ZnO, and SiC.

The bonding layer 115 may be disposed between the supporting layer 110 and the barrier layer 120 and may serve as a bonding layer for bonding the supporting layer 110 to the barrier layer 120.

The bonding layer 115 may include at least one of a metal material, for example, In, Sn, Ag, Nb, Pd, Ni, Au, The bonding layer 115 is formed to bond the supporting layer 110 by a bonding method. Therefore, when the supporting layer 110 is formed by plating or vapor deposition, the bonding layer 115 may be omitted.

The barrier layer 120 may be disposed below the reflective layer 125, the ohmic region 130, and the protective layer 140, and the metal ions of the bonding layer 115 and the support layer 110 may be disposed on the reflective layer 125, And the ohmic region 130 to diffuse into the light emitting structure 150. For example, the barrier layer 120 may include at least one of Ni, Pt, Ti, W, V, Fe, and Mo, and may be a single layer or a multilayer.

The reflective layer 125 may be disposed on the barrier layer 120 and may reflect light incident from the light emitting structure 150 to improve light extraction efficiency. The reflective layer 125 may be formed of a metal or an alloy including at least one of a reflective material such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au and Hf.

The reflective layer 125 may be formed of a metal or an alloy and a transparent conductive material such as IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO or the like. For example, IZO / Ni, AZO / Ag, IZO / Ag / Ni, AZO / Ag / Ni, or the like.

The ohmic region 130 may be disposed between the reflective layer 125 and the second semiconductor layer 152 and is ohmic contacted with the second semiconductor layer 152 to smoothly supply power to the light emitting structure 150. [ .

The ohmic region 130 may be formed by selectively using a light-transmitting conductive layer and a metal. For example, the ohmic region 130 may include at least one of a metal material that makes an ohmic contact with the second semiconductor layer 152, for example, Ag, Ni, Cr, Ti, Pd, Ir, Sn, Ru, Pt, Au, can do.

The protective layer 140 may be disposed on the edge region of the second electrode 105. For example, the protective layer 140 may be disposed on the edge region of the ohmic region 130, or the edge region of the reflective layer 125, or the edge region of the barrier layer 120, .

The protective layer 140 can prevent the reliability of the light emitting device 100 from deteriorating because the interface between the light emitting structure 150 and the second electrode 105 is peeled off. The protective layer 140 is an electrically insulating material, e.g., 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 145 may be disposed between the ohmic region 130 and the light emitting structure 150. The upper surface of the current blocking layer 145 is in contact with the second semiconductor layer 152 and the lower surface or the lower surface and the side surface of the current blocking layer 145 can be in contact with the ohmic region 130. The current blocking layer 145 may be formed between the ohmic layer 130 and the second semiconductor layer 152 or may be formed between the reflective layer 125 and the ohmic region 130. However, The current blocking layer 145 may be disposed so that at least a part of the current blocking layer 145 overlaps with the first electrode 170 in the vertical direction.

The light emitting structure 150 may be disposed on the ohmic region 130 and the protective layer 140. The side surface of the light emitting structure 150 may be an inclined surface in an isolation etching process that is divided into unit chips.

The light emitting structure 150 may include a second semiconductor layer 152, an active layer 154, an electron blocking layer 155, and a first semiconductor layer 156.

The passivation layer 165 may be disposed on the side of the light emitting structure 150 to electrically protect the light emitting structure 150. The passivation layer 165 may be disposed on the top surface of the first semiconductor layer 156 or on the top surface of the passivation layer 140. The passivation layer 165 is an insulating material, e.g., SiO _2, SiO _x, SiO _x N _y, Si ₃ N ₄ , or Al ₂ O ₃ .

The first electrode 170 may be disposed on the first semiconductor layer 156. The first electrode 170 may have a predetermined pattern shape. A roughness (not shown) may be formed on the upper surface of the first semiconductor layer 156 to increase light extraction efficiency. Roughness (not shown) may also be formed on the top surface of the first electrode 170 to increase the light extraction efficiency.

The second semiconductor layer 152 may be disposed on the ohmic region 130 and the protective layer 140.

The second semiconductor layer 152 may be formed of a compound semiconductor such as a group III-V element, a group II-VI element, or the like, and the second conductivity type dopant may be doped.

For example, the second semiconductor layer 152 is _{Al y Ga 1 --y N (0} <y <1) may be a semiconductor, p-type dopants (e.g., Mg, Zn, Ca, Sr, Ba) having a composition formula of Can be doped.

The active layer 154 can generate light by energy generated in the recombination process of electrons and holes provided from the first semiconductor layer 156 and the second semiconductor layer 152 . The embodiment can generate light having a wavelength of 250 nm to 390 nm from the active layer 154. For example, the embodiment can generate light having a wavelength of 365 nm from the active layer 154. [

The active layer 154 may be disposed between the second semiconductor layer 152 and the first semiconductor layer 156 and may be implemented with a semiconductor compound such as Group 3-Group 5, Group 2-6, have.

The active layer 154 may be a single well structure, a multi-well structure, a quantum-wire structure, a quantum dot structure, or the like.

In the case where the active layer 154 is a quantum well structure, the active layer 154 is formed of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + 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) Lt; / RTI &gt; The well layer may be a material having a band gap lower than the energy band gap of the barrier layer.

For example, the well layer is In _x Ga _{1 -} can be a _{b N (0 <b <1} ) - x N (0 <x <1) may be a barrier layer is Al _b Ga _1.

The first semiconductor layer 156 may be disposed on the active layer 154 and may be formed of compound semiconductors such as Group 3-Group 5, Group 2-Group 6, etc., and the first conductivity type dopant may be doped .

For example, the first semiconductor layer 156 is _{Al y Ga 1 - y N (} 0 <y <1) of the can be a semiconductor having a composition formula, n-type dopant (e.g.,: Si, Ge, Sn, etc.) can be doped have.

The electron blocking layer 155 may be disposed between the active layer 154 and the second semiconductor layer 152 and electrons provided from the first semiconductor layer 152 to the active layer 154 may be transmitted through the second semiconductor layer 154, As shown in FIG. The electron blocking layer 155 may have a composition formula of In _x Al _y Ga _{1 -xy} N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) Mg, Zn, Ca, Sr, Ba) may be doped.

For example, the electron blocking layer 155 may have a composition formula of Al _y Ga _{1 -yN} (0 <y <1).

The energy band gap of the first semiconductor layer 156 may increase as the active layer 154 is closer to the active layer 154 and the energy band gap of the second semiconductor layer 152 may increase as it approaches the active layer 154.

The energy band gap of the first semiconductor layer 156 may increase and the energy band gap of the second semiconductor layer 152 may decrease as the first semiconductor layer 156 proceeds in the first direction. Wherein the first direction may be a direction from the first semiconductor layer 156 to the second semiconductor layer 152.

Fig. 2 shows the energy bandgap according to the first embodiment of the light emitting structure 150 shown in Fig. 1, Fig. 3a shows the content ratio of Al in the first semiconductor layer 156 in Fig. 2, 2 shows a content ratio of Al in the second semiconductor layer 152 in FIG.

2, the energy band gap Ef of the first semiconductor layer 156 may increase as the active layer 154 is adjacent to the active layer 154, and the energy band gap Eg of the second semiconductor layer 152 may increase as the energy band gap Ef of the active layer 154 154). &Lt; / RTI &gt;

For example, the energy band gap Ef of the first semiconductor layer 156 may increase linearly in the first direction 201, and the energy band gap Eg of the second semiconductor layer 152 may be increased It can be linearly decreased as it goes in one direction (201). The first direction 201 may be a direction from the first semiconductor layer 156 to the second semiconductor layer 152.

The minimum energy band gap E1 of the first semiconductor layer 156 may be equal to or greater than the energy band gap E3 of the well layer of the active layer 154 (E1? E3). The maximum energy band gap E2 of the first semiconductor layer 156 may be smaller than or equal to the energy band gap E4 of the barrier layer of the active layer 154 (E2? E4).

The minimum energy band gap E7 of the second semiconductor layer 152 may be equal to or greater than the energy band gap E3 of the well layer of the active layer 154 (E7? E3). The maximum energy band gap E6 of the second semiconductor layer 152 may be smaller than or equal to the energy band gap E4 of the barrier layer of the active layer 154 (E6 &lt; = E4).

The energy band gap E5 of the electron blocking layer 155 may be greater than the energy band gap E4 of the barrier layer of the active layer 154 and the energy band gap Eg of the second semiconductor layer 152 (E5 > E4, E5 > Eg).

Referring to FIG. 3A, X1-X2 may be a period in which the first semiconductor layer 156 is located.

The content ratio y of Al in the first semiconductor layer 156 may increase as the active layer 154 is closer to the active layer 154. [ For example, the content ratio y of Al in the first semiconductor layer 156 may increase linearly in the first direction 201.

The content ratio y1 of the lowest Al of the first semiconductor layer 156 may be 1% or less and the content ratio y2 of the maximum Al may be 1% or less for securing high-quality crystallinity, improving the luminous efficiency, May be 7 to 10%.

When the content ratio y1 of the lowest Al exceeds 1%, it may be difficult to secure a high quality crystallinity. As the content ratio y2 of maximum Al increases, the absorption of UV light by the first semiconductor layer 156 decreases and the luminous efficiency increases. When the content ratio y2 of the maximum Al exceeds 10% Electrical characteristics such as voltage and reverse bias current may be deteriorated.

Referring to FIG. 3B, X3-X4 may be a section where the second semiconductor layer 152 is located.

The content ratio y of Al in the second semiconductor layer 152 may increase as the active layer 154 is closer to the active layer 154. For example, the content ratio y of Al in the second semiconductor layer 152 may decrease linearly in the first direction 201.

The content ratio y3 of the highest Al content of the second semiconductor layer 152 may be 7 to 10% and the content ratio of the lowest Al content (y3) may be 7 to 10% in order to ensure high quality crystallinity, y4) may be less than or equal to 1%.

As the content ratio of Al in the first semiconductor layer 156 gradually increases and the content ratio of Al in the second semiconductor layer 152 gradually decreases in the first direction 201, the first semiconductor layer 156 ) And the active layer 154 and between the active layer 154 and the second semiconductor layer 152. As a result, the first semiconductor layer 156 having good crystallinity can be formed, The active layer 154, and the second semiconductor layer 152 can be obtained.

4 is a cross-sectional view of the light emitting structure 150-1 according to the second embodiment. FIG. 5 is a cross-sectional view of the light emitting structure 150-1 according to the second embodiment. FIG. 6A shows a content ratio of Al in the first semiconductor layer 156-1 in FIG. 4, and FIG. 6B shows a content ratio of Al in the second semiconductor layer 152-1 in FIG.

Referring to FIG. 4, the first semiconductor layer 156-1 may include a plurality of first layers 310-1 to 310-m, a natural number of m> 1, and the second semiconductor layer 152-1 May comprise a plurality of second layers 320-1 through 320-m, where m> 1 is a natural number.

Referring to FIG. 5, the energy band gap Ef of the first semiconductor layer 156-1 may increase nonlinearly in the vicinity of the active layer 154, The gap Eg may increase non-linearly as the active layer 154 is adjacent to the active layer 154. [

The energy band gap Ef of the first semiconductor layer 156-1 may increase nonlinearly in the first direction 201 and the energy band gap Eg of the second semiconductor layer 152-1 may increase, May decrease nonlinearly as it goes in the first direction (201).

For example, the energy band gap Ef of the first semiconductor layer 156-1 may gradually increase as it goes in the first direction 201. [ The energy band gap Eg of the second semiconductor layer 152-1 can be gradually reduced as it goes in the first direction 201. [

The plurality of first layers 310-1 to 310-m and natural numbers of m> 1 may have different energy band gaps and the plurality of second layers 320-1 to 320-m, m> ) May have different energy band gaps.

The energy band gaps E11 to E1m of the plurality of first layers 310-1 to 310-m and the natural number of m> 1 can be increased toward the first direction 201. [ The energy band gaps (E21 to E2m, natural number of m> 1) of the plurality of second layers 320-1 to 320-m and m> 1 can increase toward the first direction 201.

The plurality of first layers 310-1 to 310-m, natural numbers of m> 1 and the second layers 320-1 to 320-m, natural numbers of m> 1 may have a superlattice structure.

Referring to FIG. 6A, the content ratio y of Al in the first semiconductor layer 156-1 may increase in a non-linear manner as it goes in the first direction 201. For example, the content ratio y of Al in the first semiconductor layer 156-1 may gradually increase toward the first direction 201. [

A plurality of first layers (310-1 to 310-m, m> 1 is a natural number) is Al _y Ga _{1 -} may have a composition formula of _{y N (0 <y <1} ). The content ratio of Al in each of the plurality of first layers 310-1 to 310-m and m> 1 can increase in the first direction 201.

The minimum content ratio y1 and the maximum content ratio ym of Al in the first semiconductor layer 156-1 may be the same as those described in Fig.

Referring to FIG. 6B, the content ratio y of Al in the second semiconductor layer 152-1 may increase in a non-linear manner as it goes in the first direction 201. For example, the content ratio y of Al in the second semiconductor layer 152-1 can be gradually decreased in the first direction 201.

The plurality of second layers 320 - 1 to 320 - m, m> 1 natural number may have a composition formula of Al _y Ga _{1 - y} N (0 <y <1). The content ratio of Al in each of the plurality of second layers 320 - 1 to 320 - m and m> 1 can be reduced toward the first direction 201.

The minimum content ratio y11 and the maximum content ratio y1m of Al in the second semiconductor layer 152-1 may be the same as those described in Fig. 3B.

The content ratio of Al in the first layers 310-1 to 310-m, m> 1 is increased, and the content ratio of Al in the second layers 320-1 to 320-m, m> It is possible to reduce the difference in lattice constant between the first semiconductor layer 156-1 and the active layer 154 and between the active layer 154 and the second semiconductor layer 152-1, For example, the first semiconductor layer 156-1, the active layer 154, and the second semiconductor layer 152-1 having good crystallinity can be obtained.

7 is a cross-sectional view of the light emitting structure 150-2 according to the third embodiment. FIG. 8 is a cross-sectional view of the light emitting structure 150-2 according to the third embodiment. FIG. 9A shows a content ratio of Al in the first semiconductor layer 156-2 in FIG. 7, and FIG. 9B shows a content ratio of Al in the second semiconductor layer 152-2 in FIG.

7, the first semiconductor layer 156-2 includes a plurality of first layers 310-1 through 310-k, a natural number of k > 1, and a third semiconductor layer 156-2 disposed between two adjacent first layers. Layer 340 as shown in FIG. The second semiconductor layer 152-2 includes a fourth layer 350 disposed between the two adjacent second layers and a plurality of second layers 320-1 through 320-k, k> 1, can do.

(A natural number of m> 1), a third layer 340, a second layer 320-1 to 320-k, a natural number of k> 1, and a fourth layer 350 may be a superlattice structure.

8, the energy band gaps (E31 to E3k, natural number of k> 1) of the first layers 310-1 to 310-k, k> 1 are increased in the first direction 201 And the energy band gaps (E41 to E4k, natural number of k> 1) of the second layers 320-1 to 320-k, k> 1 can be reduced toward the first direction 201.

The energy band gap E8 of the third layer 340 may be smaller than the energy band gaps E31 through E3k of the first layers 310-1 through 310-k and k> 1 have.

The energy band gap E9 of the fourth layer 350 may be smaller than the energy band gaps E41 to E4k of the second layers 320-1 to 320-k, natural numbers of k> 1, have.

The energy band gap E8 of the third layer 340 and the energy band gap E9 of the fourth layer 350 may be equal to each other, but are not limited thereto. The energy band gap E8 of the third layer 340 and the energy band gap E9 of the fourth layer 350 may be greater than or equal to the energy band gap E3 of the well layer of the active layer 154. [

9A, a plurality of first layers 310-1 to 310-k, a natural number of k> 1 may have a composition formula of Al _y Ga _1-y N (0 <y <1) Layer 340 may have a composition formula of Al _x Ga _{1 - x} N (0? _X <1). The content ratio of Al in the plurality of first layers 310-1 to 310-k, k> 1 can be increased in the first direction 201. The content ratio of Al in the third layer 340 may be smaller than the content ratio of Al in the first layers 310-1 to 310-k, k> 1.

The minimum content ratio y1 and the maximum content ratio yk of Al in the first semiconductor layer 156-2 may be the same as those described in Fig.

Referring to FIG. 9B, the plurality of second layers 320 - 1 to 320 - k, natural numbers of k> 1 may have a composition formula of Al _y Ga ₁ -yN (0 <y <1) The layer 350 may have a composition formula of Al _x Ga _{1 - x} N (0? _X <1).

The content ratio of Al in the plurality of second layers 320-1 to 320-k, k> 1 can be reduced as the layer progresses in the first direction 201. The content ratio of Al in the fourth layer 350 may be smaller than the content ratio of Al in the second layers 320-1 to 320-k, k> 1.

The minimum content ratio y11 and the maximum content ratio y1k of Al in the second semiconductor layer 152-2 may be the same as those described in Fig. 3B.

In the embodiment, since the Al content of the first semiconductor layer 156-2 and the second semiconductor layer 152-2 gradually increases or decreases, the first semiconductor layer 156-2 ), The active layer 154, and the second semiconductor layer 152-2 can be obtained.

10 is a cross-sectional view of a light emitting device 200 according to another embodiment.

10, a light emitting device 200 includes a substrate 10, a first semiconductor layer 156, an active layer 154, an electron blocking layer 155, a second semiconductor layer 152, a conductive layer 12, A first electrode 13, and a second electrode 14, as shown in FIG.

The substrate 10 may be formed of a material suitable for semiconductor material growth, or a carrier wafer. 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 10 to improve light extraction.

A buffer layer (not shown) may be interposed between the first semiconductor layer 156 and the substrate 10 to mitigate lattice mismatch due to the difference in lattice constant between the substrate 10 and the first semiconductor layer 156. The buffer layer may be a nitride semiconductor including Group 3 elements and Group 5 elements. For example, the buffer layer may include at least one of InAlGaN, GaN, AlN, AlGaN, and InGaN. The buffer layer may be a single layer or a multi-layer structure, and a Group 2 element or a Group 4 element may be doped with an impurity.

An undoped semiconductor layer (not shown) may be interposed between the first semiconductor layer 156 and the buffer layer. The undoped semiconductor layer (not shown) may be formed using a compound semiconductor of Group 3 and Group 5 elements, such as a GaN-based semiconductor, which is not doped.

The light emitting structure 150 'may include a first semiconductor layer 156, an active layer 154, an electron blocking layer 155, and a second semiconductor layer 152 that are sequentially stacked on the substrate 10 . The light emitting structure 150 'includes a second semiconductor layer 152, an electron blocking layer 155, an active layer 154, and a portion of the first semiconductor layer 156 to expose a region of the first semiconductor layer 156 Can be removed.

The first semiconductor layer 156, the active layer 154, the electron blocking layer 155, and the second semiconductor layer 152 may be the same as those described above, and a description thereof will be omitted to avoid redundancy.

The conductive layer 12 is disposed on the second semiconductor layer 152 and not only reduces total reflection but also increases light extraction efficiency of light emitted from the active layer 154 to the second semiconductor layer 152 .

The conductive layer 12 may be formed of a transparent conductive oxide such as ITO (Indium Tin Oxide), TO (Tin Oxide), IZO (Indium Zinc Oxide), ITZO (Indium Tin Zinc Oxide), IAZO (Indium Aluminum Zinc Oxide) Indium Gallium Zinc Oxide), IGTO (Indium Gallium Tin Oxide), AZO (Aluminum Zinc Oxide), ATO (Antimony Tin Oxide), GZO (Gallium Zinc Oxide), IrOx, RuOx, RuOx / ITO, Ni, / Au, or Ni / IrOx / Au / ITO.

The first electrode 13 may be disposed on the exposed first semiconductor layer 156 and the second electrode 14 may be disposed on the conductive layer 13.

11 shows a light emitting device package 600 according to the embodiment.

11, the light emitting device package 600 includes a package body 610, lead frames 612 and 614, a light emitting device 620, a reflector 625, a wire 630, and a resin layer 640 do.

A cavity may be formed on the upper surface of the package body 610. The side wall of the cavity may be formed obliquely. The package body 610 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 embodiment is not limited to the material, structure and shape of the package body 610.

The lead frames 612 and 614 are disposed on the package body 610 so as to be electrically separated from each other in consideration of heat discharge or mounting of the light emitting device. The light emitting element 620 is electrically connected to the lead frames 612 and 614. The light emitting device 620 may be any of the embodiments 100 and 200.

The reflection plate 625 is formed on the cavity side wall of the package body 610 so as to direct the light emitted from the light emitting element in a predetermined direction. The reflector 625 is made of a light reflecting material, for example, a metal coating or a metal flake.

The resin layer 640 surrounds the light emitting element 620 located in the cavity of the package body 610 to protect the light emitting element 620 from the external environment. The resin layer 640 may be made of a colorless transparent polymer resin material such as epoxy or silicone. The resin layer 640 may include a phosphor to change the wavelength of the light emitted from the light emitting device 620.

12 is an exploded perspective view of a lighting device including a light emitting device package according to an embodiment. 12, the illumination device includes a light source 750 that emits light, a heat dissipation unit 740 that emits heat of the light source, a housing 700 that houses the light source 750 and the heat dissipation unit 740, And a holder 760 coupling the light source 750 and the heat dissipating unit 740 to the housing 700.

The housing 700 may include 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 may be 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 may include a plurality of light emitting device packages 752 mounted 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. For example, the light emitting device package 752 may be the embodiment 600 shown in FIG.

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.

13 shows a display device including the light emitting device package according to the embodiment. 13, 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 may include light emitting device packages 835 mounted on the substrate 830. Here, the substrate 830 may be a PCB or the like, and the light emitting device package 835 may be the embodiment 600 shown in FIG.

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 860 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.

14 shows a head lamp 900 including the light emitting device package according to the embodiment. 14, the head lamp 900 includes a light emitting module 901, a reflector 902, a shade 903, and a lens 904.

The light emitting module 901 may include a light emitting device package 600 according to an embodiment disposed on a substrate (not shown).

The reflector 902 reflects the light 911 emitted from the light emitting module 901 in a predetermined direction, for example, toward the front 912.

The shade 903 is disposed between the reflector 902 and the lens 904 and reflects off or reflects a part of the light reflected by the reflector 902 toward the lens 904 to form a light distribution pattern desired by the designer. The one side portion 903-1 and the other side portion 903-2 of the shade 903 may have different heights from each other.

The light emitted from the light emitting module 901 can be reflected by the reflector 902 and the shade 903 and then transmitted through the lens 904 and directed toward the front of the vehicle body. The lens 904 can refract the light reflected by the reflector 902 forward.

 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.

105: second electrode 140: protective layer
145: current blocking layer 150: light emitting structure
152: second semiconductor layer 154: active layer
156: first semiconductor layer 165: passivation layer
170: first electrode.

Claims (16)

A first semiconductor layer;
An active layer disposed under the first semiconductor layer; And
And a second semiconductor layer disposed under the active layer,
Wherein the energy band gap of the first semiconductor layer increases as the first semiconductor layer progresses in the first direction, the energy band gap of the second semiconductor layer decreases as the first semiconductor layer progresses in the first direction, And a direction toward the second semiconductor layer. The method according to claim 1,
Wherein the composition formula of the first semiconductor layer is Al _y Ga _{1 -y} N (0 <y <1), the composition formula of the second semiconductor layer is Al _x Ga _{1 -x} N (0 <x <1) Wherein the Al content ratio of the first semiconductor layer is increased as the first semiconductor layer is grown in the first direction and the Al content ratio of the second semiconductor layer is decreased as the first semiconductor layer is grown in the first direction. 3. The method of claim 2,
Wherein a content ratio of Al in the first semiconductor layer linearly increases and a content ratio of Al in the second semiconductor layer decreases linearly. 3. The method of claim 2,
Wherein an Al content ratio of the first semiconductor layer is gradually increased, and a content ratio of Al in the second semiconductor layer is gradually reduced. The semiconductor device according to claim 2,
Wherein a content ratio of Al in the plurality of first layers increases in the first direction. The semiconductor device according to claim 2,
Wherein a content ratio of Al in the plurality of second layers decreases in the first direction. 6. The semiconductor device according to claim 5,
2 is disposed between adjacent two first layers, the light emitting device further includes a third layer having a composition formula of _{Al a Ga 1 -a N (0≤a} <1) to. 8. The method of claim 7,
Wherein a content ratio of Al in the third layer is smaller than a content ratio of Al in the first layers. 7. The semiconductor device according to claim 6,
And a fourth layer disposed between two adjacent second layers and having a composition formula of Al _b Ga _{1 -b} N (0? B <1). 10. The method of claim 9,
Wherein a content ratio of Al in the fourth layer is smaller than a content ratio of Al in the second layers. 8. The method of claim 7,
Wherein the first layers and the third layer are superlattice structures. 10. The method of claim 9,
Wherein the second layers and the fourth layer have a superlattice structure. The method according to claim 1,
Wherein an energy band gap of the first semiconductor layer increases linearly and an energy band gap of the second semiconductor layer decreases linearly. The method according to claim 1,
Wherein an energy band gap of the first semiconductor layer is gradually increased, and an energy band gap of the second semiconductor layer is reduced in a stepwise manner. The method according to claim 1,
A first electrode disposed on the first semiconductor layer;
A reflective layer disposed below the second semiconductor layer;
An ohmic region disposed between the second semiconductor layer and the reflective layer; And
And a support layer disposed under the reflective layer. The method according to claim 1,
Wherein the active layer generates light having a wavelength of 250 nm to 390 nm.

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