KR102249647B1 - Light emitting device and lighting system - Google Patents

Abstract

The embodiment relates to a light emitting device, a method of manufacturing a light emitting device, a light emitting device package and a lighting system.
The light emitting device according to the embodiment includes a first conductivity type semiconductor layer 112; A gallium nitride-based super lattice layer 111 on the first conductivity type semiconductor layer 112; _{An In x} Al _1-x N layer (0<x<1) 113 on the gallium nitride-based superlattice layer 111; An active layer 114 on the In _x Al _{1-x N layer 113;} And a second conductivity type semiconductor layer 116 on the active layer 114.

Description

Light emitting device and lighting system {LIGHT EMITTING DEVICE AND LIGHTING SYSTEM}

The embodiment relates to a light emitting device, a method of manufacturing a light emitting device, a light emitting device package, and a lighting system.

A light emitting device may be generated by combining a group III and a group V element on the periodic table with a p-n junction diode that converts electric energy into light energy. LED can realize various colors by controlling the composition ratio of compound semiconductor.

When the forward voltage is applied, the electrons in the n-type semiconductor layer and the holes in the p-type semiconductor layer are combined in the active layer, which is the emission layer, corresponding to the energy gap between the conduction band and the valence band. It radiates energy as much as it does, but when it is radiated in the form of light, it can become a light-emitting device.

For example, nitride semiconductors are attracting great interest in the development of optical devices and high-power electronic devices due to their high thermal stability and wide bandgap energy. In particular, a blue light emitting device, a green light emitting device, and an ultraviolet (UV) light emitting device using a nitride semiconductor have been commercialized and widely used.

According to the prior art, there is a case where a V-pit occurs in the active layer, which is a light emitting layer, but the thickness of the active layer grown at the facet of the V-pit is relatively thin and thus has a relatively high energy. The energy barrier serves to prevent electrons or holes, which are carriers, from going to dislocation, thereby enhancing luminous efficiency, but at high temperatures, thermal energy causes the carrier to surpass such high energy and thus the V-pit The advantage of this will be lost.

On the other hand, according to the prior art, the effective light emitting area decreases due to the occurrence of the V-pit, so that the light output decreases at high temperatures.

Accordingly, according to the prior art, it is necessary to reduce the V-pit of the light emitting layer in order to improve the reduction in light output.

The embodiment is to provide a light emitting device capable of improving luminous efficiency, a method of manufacturing the same, a light emitting device package, and a lighting system.

The light emitting device according to the embodiment includes a first conductivity type semiconductor layer 112; A gallium nitride-based super lattice layer 111 on the first conductivity type semiconductor layer 112; _{An In x} Al _1-x N layer (0<x<1) 113 on the gallium nitride-based superlattice layer 111; An active layer 114 on the In _x Al _{1-x N layer 113;} And a second conductivity type semiconductor layer 116 on the active layer 114.

The lighting system according to the embodiment may include a light emitting unit including the light emitting device.

According to the embodiment, a light emitting device having improved luminous efficiency, a method of manufacturing a light emitting device, a light emitting device package, and a lighting system can be provided.

1 is a cross-sectional view of a light emitting device according to an embodiment.
2 is a photograph of a first portion of a light emitting device according to the embodiment.
3 is a second partial photograph of the light emitting device according to the embodiment.
4 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment.
7 is a cross-sectional view of a light emitting device package according to an embodiment.
8 is an exploded perspective view of a lighting device according to the embodiment.

In the description of the embodiment, each layer (film), region, pattern, or structure is "on/over" or "under" of the substrate, each layer (film), region, pad, or patterns. In the case of being described as being formed in, "on/over" and "under" include both "directly" or "indirectly" formed. do. In addition, the criteria for the top/top or bottom of each layer will be described based on the drawings.

(Example)

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

The embodiment is to provide a light emitting device capable of improving luminous efficiency.

To this end, the light emitting device 100 according to the embodiment includes a first conductivity-type semiconductor layer 112, a gallium nitride-based superlattice layer 111 on the first conductivity-type semiconductor layer 112, and the gallium nitride. series superlattice layer 111 onto the in _x Al _{1 - x} N layer (0 <x <1) 113 and the in _x Al _{1 - x} N layer an active layer 113, 114 and the active layer A second conductivity type semiconductor layer 116 may be included on the 114. The first conductivity type semiconductor layer 112, the active layer 114, and the second conductivity type semiconductor layer 116 may be referred to as a light emitting structure 110.

The gallium nitride-based superlattice layer 111 may include an In _y Ga _{1 -y} N (0<x<1)/GaN superlattice layer. Alternatively, the gallium nitride-based superlattice layer 111 may include In _y Al _x Ga _(1-xy) N (0≦x≦1, 0≦y≦1)/GaN.

According to an embodiment, a gallium nitride-based superlattice layer 111 is provided between the first conductivity type semiconductor layer 112 and the active layer 114, and the first conductivity type semiconductor layer 112 and the active layer 114 are provided. The stress caused by the grid mismatch between) can be effectively relieved.

The gallium nitride-based superlattice layer 111 is _{repeatedly stacked with a structure of a first In x1} GaN/GaN layer (0<x1<1) and a second In _x2 GaN/GaN layer (0<x2<1) at least 6 cycles Accordingly, more electrons are collected in the active layer 114 according to potential blocking and stress relaxation, and as a result, the probability of recombination of electrons and holes is increased, thereby improving luminous efficiency.

2 is a photograph of a first portion of a light emitting device according to the embodiment, which is a photographic image of an upper portion of a gallium nitride-based superlattice layer 111. According to the embodiment, the size of the V-pit (V) is reduced compared to the prior art, but the V-pit (V) may exist on the upper part of the gallium nitride-based superlattice layer 111 as shown in FIG. 2.

This V-pit (V) may cause a decrease in the light emitting area in the active layer and cause an overflow of carriers, thereby reducing light output.

3 is a second partial photograph of the light emitting device according to the embodiment, in which an In _x Al _{1 - x} N layer (0<x<1) 113 disposed on the gallium nitride-based superlattice layer 111 is shown. This is a photographic image.

According to the embodiment, it can be seen that the V-pit (V) is almost merged on the top of the _{In x} Al _{1 - x N layer (0<x<1) 113 as shown in FIG. 3.}

Accordingly, according to an embodiment, the In _x Al _{1 - x} N layer (0<x<1) 113 disposed on the gallium nitride-based superlattice layer 111 is generated in the gallium nitride-based superlattice layer 111 By merging the V-pit (V), it is possible to increase the light output by minimizing or removing the V-pit (V), which inhibits the light output by causing a decrease in the light emitting area in the active layer or causing an overflow of the carrier. .

In an embodiment _{, the indium composition (x) in the In x} Al _{1 - x} N layer 113 may be greater than the indium composition (y) in the gallium nitride series superlattice layer 111.

For example, the _{indium composition (x) in the In x} Al _{1 - x} N layer 113 may range from about 10% or more to about 20% or less.

If the _{indium composition (x) in the In x} Al _{1 - x} N layer 113 is less than 10%, the difference in lattice constant from the active layer may increase, resulting in lattice defects. If it exceeds 20%, the lattice constant The large volume of indium may increase and the crystal quality may deteriorate.

In the embodiment _{, the indium composition (x) in the In x} Al _{1 - x} N layer 113 is greater than the indium composition (y) in the gallium nitride-based superlattice layer 111 and is about 10% or more to about 20% or less As it is controlled within the range of _{, the lattice constant of the In x} Al _1-x N layer 113 is the same as that of GaN or a similar lattice constant in the range of ±10% is maintained, thereby minimizing the occurrence of lattice defects and improving the nodule quality. Thus, the internal luminous efficiency can be increased.

In an embodiment _{, the thickness of the In x} Al _{1 - x} N layer 113 may be smaller than the thickness of the gallium nitride-based superlattice layer 111. Through this, it is possible to effectively merge the V-pit (V) while preventing the occurrence of lattice defects while being disposed between the gallium nitride-based superlattice layer 111 and the active layer 114 with a minimum thickness.

For example, the _{thickness of the In x} Al _{1 - x} N layer 113 is controlled to be in the range of about 1 nm to about 5 nm, thereby effectively merging the V-pit (V), and In _x Al _{1 - x} N layer 113 It is possible to prevent the occurrence of lattice defects by appropriately controlling the volume of ).

When the _{thickness of the In x} Al _{1 - x} N layer 113 is less than 1 nm, it is difficult to perform the V-pit (V) merge function as it is too thin, and when it is 5 nm or more, lattice defects occur or carrier injection is performed. It may interfere.

In an embodiment, the In _x Al _{1 - x} N layer 113 may be doped with a first conductivity type element. For example, as the In _x Al _{1 - x} N layer 113 is doped with an n-type doping element, for example, Si, electron injection efficiency may be increased.

Accordingly, according to the embodiment, a light emitting device having improved luminous efficiency can be provided.

Hereinafter, a method of manufacturing a light emitting device according to an embodiment will be described with reference to FIGS. 4 to 6.

First, a substrate 102 is prepared as shown in FIG. 4. The substrate 102 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. For example, the substrate 102 is sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, or Ga ₂ 0 ₃ At least one of can be used. An uneven structure may be formed on the substrate 102, but the embodiment is not limited thereto.

Thereafter, a buffer layer (not shown) may be formed on the substrate 102. The buffer layer can alleviate lattice mismatch between the material of the light emitting structure 110 and the substrate 102, and the material of the buffer layer is a group III-5 compound semiconductor such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, It may be formed of at least one of AlInN.

Thereafter, a first conductivity type semiconductor layer 112 may be formed on the buffer layer.

The first conductivity type semiconductor layer 112 may be formed of a semiconductor compound. It may be implemented with a compound semiconductor such as Group 3-5 and Group 2-6, and may be doped with a first conductivity type dopant. When the first conductivity-type semiconductor layer 112 is an N-type semiconductor layer, the first conductivity-type dopant is an N-type dopant, and may include Si, Ge, Sn, Se, and Te, but is not limited thereto.

The first conductivity type semiconductor layer 112 is made _{of a semiconductor material having a composition formula of In x} Al _y Ga _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). Can include. For example, the first conductivity type semiconductor layer 112 is formed of one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP. Can be.

Thereafter, a gallium nitride-based superlattice layer 111 may be formed on the first conductivity type semiconductor layer 112. The gallium nitride-based superlattice layer 111 is In _y Al x Ga _{(1-xy) N (0 ≤ x ≤} 1, 0 ≤ y ≤ 1) / GaN super lattice layer or In _y Ga _{1 -y} N (0 It may include a <x<1)/GaN super lattice layer.

According to an embodiment, a gallium nitride-based superlattice layer 111 is provided between the first conductivity type semiconductor layer 112 and the active layer 114, and the first conductivity type semiconductor layer 112 and the active layer 114 are provided. The stress caused by the grid mismatch between) can be effectively relieved.

In addition, the gallium nitride-based superlattice layer 111 _{repeats the structures of the first In x1} GaN/GaN layer (0<x1<1) and the second In _x2 GaN/GaN layer (0<x2<1) at least 6 cycles As they are stacked, more electrons are collected at a low energy level of the active layer 114 according to potential blocking and stress relaxation, and as a result, the probability of recombination of electrons and holes increases, thereby improving luminous efficiency.

On the other hand, as shown in FIG. 2, a V-pit (V) may exist on the upper part of the gallium nitride-based superlattice layer 111, and this V-pit (V) causes a reduction in the light emitting area in the active layer, or It can cause a flow and reduce the light output.

Accordingly, according to an embodiment, an In _x Al _{1 - x} N layer (0<x<1) 113 may be formed on the _{gallium nitride-based superlattice layer 111, and as shown in FIG. 3, In x} Al _{1 -} there _x N layer (0 <x <1) ( 113) V-pit (V) at the top of this can be seen that substantially the remaining (merge).

Accordingly, according to the embodiment, the In _x Al _{1 - x} N layer (0 <x <1) 113 is merged with the V-pit (V) generated in the gallium nitride series superlattice layer 111, The light output can be increased by minimizing or removing the V-pit (V), which decreases the light output by causing a decrease in the light emitting area or causing an overflow of the carrier.

In an embodiment _{, the indium composition (x) in the In x} Al _{1 - x} N layer 113 may be greater than the indium composition (y) in the gallium nitride series superlattice layer 111. For example, the _{indium composition (x) in the In x} Al _{1 - x} N layer 113 may range from about 10% or more to about 20% or less.

If the _{indium composition (x) in the In x} Al _{1 - x} N layer 113 is less than 10%, the difference in lattice constant from the active layer may increase, resulting in lattice defects. If it exceeds 20%, the lattice constant The large volume of indium may increase and the crystal quality may deteriorate.

In the embodiment _{, the indium composition (x) in the In x} Al _{1 - x} N layer 113 is greater than the indium composition (y) in the gallium nitride-based superlattice layer 111 and is about 10% or more to about 20% or less As it is controlled in the range of, it is possible to increase internal luminous efficiency by minimizing the occurrence of lattice defects by maintaining a lattice constant equal to or similar to the lattice constant of GaN in the range of ±10% to improve nodular quality.

In an embodiment _{, the thickness of the In x} Al _{1 - x} N layer 113 may be smaller than the thickness of the gallium nitride-based superlattice layer 111. Through this, it is possible to effectively merge the V-pit (V) while preventing the occurrence of lattice defects while being disposed between the gallium nitride-based superlattice layer 111 and the active layer 114 with a minimum thickness.

For example, the _{thickness of the In x} Al _{1 - x} N layer 113 is controlled to be in the range of about 1 nm to about 5 nm, thereby effectively merging the V-pit (V), and In _x Al _{1 - x} N layer 113 It is possible to prevent the occurrence of lattice defects by appropriately controlling the volume of ).

When the _{thickness of the In x} Al _{1 - x} N layer 113 is less than 1 nm, it is difficult to perform the V-pit (V) merge function as it is too thin, and when it is 5 nm or more, lattice defects occur or carrier injection is performed. It may interfere.

In an embodiment, the In _x Al _{1 - x} N layer 113 may be doped with a first conductivity type element. For example, as the In _x Al _{1 - x} N layer 113 is doped with an n-type doping element, for example, Si, electron injection efficiency may be increased.

Next, an active layer 114 may be formed on _{the In x} Al _{1 - x N layer 113.}

The active layer 114 may be formed of at least one of a single quantum well structure, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure. For example, in the active layer 114, trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) may be injected to form a multiple quantum well structure. It is not limited thereto.

The active layer 114 has a quantum well/double barrier structure, for example, any one of InGaN/GaN, InGaN/InGaN, GaN/AlGaN, InAlGaN/GaN, GaAs/AlGaAs, InGaAs/AlGaAs, GaP/AlGaP, InGaP/AlGaP It may be formed in the above pair structure, but is not limited thereto.

Next, in the embodiment, an electron blocking layer 118 is formed on the active layer 114 to serve as electron blocking and MQW cladding of the active layer, thereby improving luminous efficiency. For example, the electron blocking layer 118 may be formed of an Al _x In _y Ga _(1-xy) N (0≦x≦1,0≦y≦1) based semiconductor, and the active layer 114 It may have a higher energy band gap than the energy band gap.

Thereafter, the second conductivity-type semiconductor layer 116 on the electron blocking layer 118 may be implemented with a semiconductor compound, for example, a compound semiconductor such as Group 3-5, Group 2-6, etc. A second conductivity type dopant may be doped.

For example, the second conductivity type semiconductor layer 116 has _{a composition formula of In x} Al _y Ga _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) It may include a semiconductor material having. When the second conductivity-type semiconductor layer 116 is a p-type semiconductor layer, the second conductivity-type dopant is a p-type dopant and may include Mg, Zn, Ca, Sr, Ba, or the like.

In the embodiment, an example in which the first conductivity-type semiconductor layer 112 is an n-type semiconductor layer and the second conductivity-type semiconductor layer 116 is a p-type semiconductor layer has been described, but is not limited thereto.

Meanwhile, a semiconductor, for example, an n-type semiconductor layer (not shown) having a polarity opposite to that of the second conductivity type may be formed on the second conductivity type semiconductor layer 116. Accordingly, the light emitting structure 110 may be implemented in any one of an n-p junction structure, a p-n junction structure, an n-p-n junction structure, and a p-n-p junction structure.

Thereafter, a light-transmitting electrode 130 may be formed on the second conductivity-type semiconductor layer 116. For example, the light-transmitting electrode 130 may include an ohmic layer, and may be formed by stacking a single metal, a metal alloy, or a metal oxide in a single or multi-layered structure to efficiently inject holes.

For example, the light-transmitting electrode 130 may include indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), and IGTO. (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, and Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt , Au, and may be formed to include at least one of Hf, but is not limited to these materials.

Next, as shown in FIG. 5, the light-transmitting electrode 130, the second conductivity-type semiconductor layer 116, the electron blocking layer 118, and the active layer 114, In so that the first conductivity-type semiconductor layer 112 is exposed. _{A part of the x} Al _{1 - x} N layer (0<x<1) 113 and the gallium nitride-based superlattice layer 111 may be removed to form the mesa edge region H.

Next, as shown in FIG. 6, a second electrode 152 is formed on the light-transmitting electrode 130 and a first electrode 151 is formed on the exposed first conductivity-type semiconductor layer 112 to emit light according to the embodiment. Devices can be formed.

The embodiment can provide a light emitting device capable of increasing luminous efficiency, a method of manufacturing a light emitting device, a light emitting device package, and a lighting system.

A plurality of light emitting devices according to the embodiment may be arrayed on a substrate in the form of a package, and an optical member, such as a light guide plate, a prism sheet, a diffusion sheet, and a fluorescent sheet, may be disposed on a path of light emitted from the light emitting device package.

The light emitting device according to the embodiment may be applied to a backlight unit, a lighting unit, a display device, an indication device, a lamp, a street light, a vehicle lighting device, a vehicle display device, a smart watch, etc., but is not limited thereto.

7 is a diagram illustrating a light emitting device package in which a light emitting device is installed according to embodiments.

The light emitting device package according to the embodiment includes a package body part 205, a third electrode layer 213 and a fourth electrode layer 214 installed on the package body part 205, and the package body part 205. A light emitting device 100 electrically connected to the third electrode layer 213 and the fourth electrode layer 214, and a molding member 230 surrounding the light emitting device 100 including a phosphor 232 .

The third electrode layer 213 and the fourth electrode layer 214 are electrically separated from each other and serve to provide power to the light emitting device 100. In addition, the third electrode layer 213 and the fourth electrode layer 214 may serve to increase light efficiency by reflecting light generated from the light emitting device 100, and It can also play a role in discharging heat to the outside.

The light emitting device 100 may be electrically connected to the third electrode layer 213 and/or the fourth electrode layer 214 by any one of a wire method, a flip chip method, or a die bonding method.

8 is an exploded perspective view of a lighting system according to an embodiment.

The lighting device according to the embodiment may include a cover 2100, a light source module 2200, a radiator 2400, a power supply unit 2600, an inner case 2700, and a socket 2800. In addition, the lighting device according to the embodiment may further include at least one of the member 2300 and the holder 2500. The light source module 2200 may include a light emitting device or a light emitting device package according to the embodiment.

The light source module 2200 may include a light source unit 2210, a connection plate 2230, and a connector 2250. The member 2300 is disposed on the upper surface of the radiator 2400 and has guide grooves 2310 into which a plurality of light source units 2210 and a connector 2250 are inserted.

The holder 2500 blocks the receiving groove 2719 of the insulating part 2710 of the inner case 2700. Accordingly, the power supply unit 2600 accommodated in the insulating unit 2710 of the inner case 2700 is sealed. The holder 2500 has a guide protrusion 2510.

The power supply unit 2600 may include a protrusion 2610, a guide portion 2630, a base 2650, and an extension 2670. The inner case 2700 may include a molding unit together with the power supply unit 2600 therein. The molding portion is a portion in which the molding liquid is solidified, and allows the power supply unit 2600 to be fixed inside the inner case 2700.

Features, structures, effects, and the like described in the embodiments above are included in at least one embodiment, 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 for other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the embodiments.

Although the embodiments have been described above, these are only examples and are not intended to limit the embodiments, and those of ordinary skill in the field to which the embodiments belong are not departing from the essential characteristics of the present embodiment. It will be seen that branch transformation and application are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the embodiments set in the appended claims.

The first conductivity type semiconductor layer 112, the gallium nitride-based super lattice layer 111,
In _x Al _1-x N layer (0<x<1) (113), active layer 114, second conductivity type semiconductor layer 116

Claims (10)

A first conductivity type semiconductor layer disposed on the substrate;
A gallium nitride-based super lattice layer disposed on the first conductivity type semiconductor layer;
_{An In x} Al _1-x N layer (0<x<1) disposed on the gallium nitride-based superlattice layer;
An active layer disposed on the In _x Al _{1-x N layer;}
A second conductivity type semiconductor layer disposed on the active layer;
A light-transmitting electrode disposed on the second conductivity-type semiconductor layer;
A first electrode disposed on the first conductivity type semiconductor layer; And
Including a second electrode disposed on the translucent electrode,
The first conductivity-type semiconductor layer includes the gallium nitride-based superlattice layer, the In _x Al _1-x N layer, the active layer, the second conductivity-type semiconductor layer, and a mesa edge region from which a part of the light-transmitting electrode is removed. and,
The first electrode is disposed on the mesa edge region of the first conductivity type semiconductor layer,
The In _x Al _1-x N layer is doped with a first conductivity type element,
The gallium nitride-based super lattice layer includes a V-pit formed on the top,
The lowermost end of the V-pit is disposed above the lower surface of the gallium nitride series superlattice layer,
The gallium nitride-based superlattice layer includes an In _y Ga _1-y N (0<x<1)/GaN superlattice layer structure that is repeatedly stacked in at least 6 cycles,
The In _x Al _1-x N layer is disposed to fill the V-pit,
The indium composition (x) in the In _x Al _1-x N layer is in the range of 10%≦x≦20%, and is greater than the indium composition (y) in the gallium nitride-based superlattice layer,
The thickness of the In _x Al _1-x N layer is smaller than the thickness of the gallium nitride-based superlattice layer, and has a thickness of 1 nm to 5 nm. delete delete delete delete delete delete delete delete delete

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