KR102471685B1 - Light emitting device and lighting apparatus - Google Patents

Abstract

Embodiments relate to a light emitting device, a method for manufacturing a light emitting device, a light emitting device package, and a lighting device.
An embodiment may include a first conductivity type semiconductor layer, an active layer disposed on the first conductivity type semiconductor layer including a quantum well and a quantum wall, and a second conductivity type semiconductor layer disposed on the active layer. The quantum well may include a first quantum well on the first conductivity type semiconductor layer and a second quantum well on the first quantum well. A composition of indium in the second quantum well may be higher than a composition of indium in the first quantum well.

Description

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

Embodiments relate to a light emitting device, a method for manufacturing a light emitting device, a light emitting device package, and a lighting device.

A light emitting diode (LED) is one of the light emitting elements that emit light when current is applied, and can emit light with high efficiency at a low voltage, thereby providing excellent energy saving effects. Recently, the luminance problem of light emitting diodes has been greatly improved, and they are applied to various devices such as backlight units of liquid crystal display devices, electronic signboards, displays, and home appliances.

For example, nitride semiconductors are of great interest in the field of developing optical devices and high-power electronic devices due to their high thermal stability and wide bandgap energy. In particular, blue light emitting devices, green light emitting devices, ultraviolet (UV) light emitting devices, red light emitting devices, and the like using nitride semiconductors are commercialized and widely used.

Light emitting devices according to the prior art include a horizontal type light emitting device in which an electrode layer is disposed in one direction of an epitaxial layer and a vertical type light emitting device in which an electrode layer is disposed on a lower surface and an upper surface of an epitaxial layer.

In the prior art, in the light emitting device, electrons injected from the n-type semiconductor layer and holes injected from the p-type semiconductor layer are recombinated in a quantum well of the active layer, and light corresponding to the band gap energy of the quantum well is generated. Since it emits light, a quantum well is an important factor influencing the characteristics of an LED.

On the other hand, according to the prior art, the quantum well of the active layer contains In like the InGaN-based layer, and the formation of non-uniform indium clusters in the quantum well causes a dense distribution of non-uniform carriers, resulting in a decrease in internal quantum efficiency and light output. there is a problem

Embodiments are intended to uniformly improve the dense distribution of non-uniform carriers in a quantum well to provide a light emitting device with improved internal quantum efficiency and light output, a method for manufacturing a light emitting device, a light emitting device package, and a lighting device.

An embodiment may include a first conductivity type semiconductor layer, an active layer disposed on the first conductivity type semiconductor layer including a quantum well and a quantum wall, and a second conductivity type semiconductor layer disposed on the active layer. The quantum well may include a first quantum well on the first conductivity type semiconductor layer and a second quantum well on the first quantum well. A composition of indium in the second quantum well may be higher than a composition of indium in the first quantum well.

A lighting device according to an embodiment may include a light emitting unit having the light emitting element.

The embodiment can provide a light emitting device with improved internal quantum efficiency and light output by uniformly improving the dense distribution of carriers by forming a uniform indium cluster in a quantum well, a method for manufacturing a light emitting device, a light emitting device package, and a lighting device. have.

For example, according to the embodiment, a uniform potential distribution is formed by forming a uniform indium cluster in the quantum well by arranging the second quantum well of a high concentration indium composition in the quantum well of the active layer so as to be in contact with the quantum wall, thereby forming internal quantum efficiency. By significantly increasing IQE, it is possible to improve light output and efficiency droop.

1 is a cross-sectional view of a light emitting device according to an embodiment.
Figure 2 is a carrier distribution diagram of a light emitting device according to the prior art.
3 is a partially enlarged view of an active layer of a light emitting device according to an embodiment.
4 is an exemplary diagram of a bandgap of an active layer of a light emitting device according to an embodiment.
5 is a carrier distribution diagram of a light emitting device according to an embodiment.
6 to 8 are cross-sectional views of a manufacturing method of a light emitting device according to an embodiment.
9 is a cross-sectional view of a light emitting device package according to an embodiment.
10 is a perspective view of a lighting device according to an embodiment;

In the description of the embodiment, each layer (film), region, pattern or structure is "on/over" or "under" the substrate, each layer (film), region, pad or pattern. In the case where it is described as being formed in, "on/over" and "under" include both "directly" or "indirectly" formed through another layer. 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. 1 is shown based on a horizontal light emitting device, but is not limited thereto, and may be applied to a vertical light emitting device.

The light emitting device according to the embodiment includes a substrate 105, a buffer layer 113, a light emitting structure layer 110, an electron blocking layer 118, a light transmitting electrode layer 140, a current spreading layer 130, a first electrode 151, At least one of the second electrodes 152 may be included. An uneven structure P may be formed on the substrate 105 .

The light emitting structure layer 110 may include a first conductivity type semiconductor layer 112 , an active layer 114 , and a second conductivity type semiconductor layer 116 .

2 is a carrier distribution diagram of a light emitting device according to the prior art.

According to the prior art, due to the formation of non-uniform indium clusters in a quantum well including an InGaN-based layer, a dense distribution of non-uniform carriers (I: Inhomogeneous) occurs, resulting in a decrease in internal quantum efficiency and light output.

Accordingly, the embodiment seeks to uniformly improve the dense distribution of non-uniform carriers in a quantum well to improve internal quantum efficiency, thereby providing a light emitting device with improved light output.

3 is a partially enlarged view of an active layer of a light emitting device according to an embodiment, and FIG. 4 is an exemplary diagram of a band gap of an active layer of a light emitting device according to an embodiment.

As shown in FIG. 3 , the embodiment includes the first conductivity type semiconductor layer 112, the quantum well 114W, and the quantum wall 114B to solve the technical problem, on the first conductivity type semiconductor layer 112. It may include an active layer 114 disposed on and a second conductive semiconductor layer 116 disposed on the active layer 114 .

At this time, the quantum well 114W of the embodiment includes a first quantum well 114W1 on the first conductivity-type semiconductor layer 116 and a second quantum well 114W2 on the first quantum well 114W1. And, the indium composition of the second quantum well 114W2 may be higher than the indium composition of the first quantum well 114W1.

For example, the first quantum well 114W1 includes In _x Ga _{1 - x} N (provided that 0<x<1), and the composition (x) of indium of the first quantum well 114W1 is about 13% to about 15%, but is not limited thereto.

In addition, the second quantum well 114W2 includes In _y Ga _{1 - y} N (provided that 0<y<1), and the composition (y) of indium of the second quantum well 114W2 is about 18% to about 20%.

If the indium composition of the second quantum well 114W2 is less than 18%, a uniform indium cluster may not be formed, and if it exceeds 20%, crystal quality may be deteriorated.

4 is an exemplary diagram of a band gap of an active layer of a light emitting device according to an embodiment.

As shown in FIGS. 3 and 4, in the embodiment, the second quantum well 114W2 is disposed in contact with the quantum wall 114B, so that the second quantum well 114W2 having a high indium composition does not have an indium composition or has a very indium composition. Indium clusters (C) may be uniformly formed by a difference in band gap energy (Eg) between the lower quantum walls 114B.

5 is a carrier distribution diagram of a light emitting device according to an embodiment.

According to the embodiment, a uniform indium cluster (C ) to form a homogeneous potential distribution (H: Homogeneous) to significantly increase the internal quantum efficiency (IQE), thereby improving light output and improving efficiency droop.

Referring back to FIG. 3 , in an embodiment, the second quantum well 114W2 may have a thickness of about 5 Å (Angstroms) to about 10 Å (Angstroms). When the thickness of the second quantum well 114W2 is less than 5 Å, indium clusters may not be formed in the second quantum well 114W2. output may decrease.

In an embodiment, the second quantum well 114W2 includes an indium cluster C, and the thickness of the indium cluster C may be greater than or equal to the thickness of the second quantum well 114W2.

For example, the size of the indium cluster (C) may be about 10 Å (angstroms) to about 15 Å (angstroms). When the size of the indium cluster (C) is less than 10 Å, a uniform carrier distribution may not be formed, and when the size exceeds 15 Å, agglomeration may occur in the InGaN-based quantum well, resulting in reduced light output.

The embodiment can provide a light emitting device and a lighting device with improved internal quantum efficiency and light output by uniformly improving the dense distribution of carriers by forming a uniform indium cluster in a quantum well.

Hereinafter, a method of manufacturing a light emitting device according to an embodiment will be described with reference to FIGS. 6 to 8 .

First, the substrate 105 may be prepared as shown in FIG. 6 . The substrate 105 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate.

For example, the substrate 105 may include GaAs, sapphire (Al ₂ O ₃ ), SiC, Si, GaN, ZnO, GaP, InP, Ge, and Ga ₂ 0 ₃ At least one of them may be used. A concavo-convex structure P may be formed on the substrate 105 to improve light extraction efficiency, but the concavo-convex structure P is not essential. Impurities on the surface of the substrate 105 may be removed by performing wet cleaning.

A buffer layer 113 may be formed on the substrate 105 . The buffer layer 113 can mitigate lattice mismatch between the light emitting structure layer 110 and the substrate 105 to be formed later.

The buffer layer 113 may be formed of at least one of Group III-V compound semiconductors, for example, GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. An undoped semiconductor layer (not shown) may be formed on the buffer layer, but is not limited thereto.

Thereafter, a light emitting structure layer 110 including a first conductivity type semiconductor layer 112, an active layer 114, and a second conductivity type semiconductor layer 116 may be formed on the substrate 105 or the buffer layer. .

The first conductivity-type semiconductor layer 112 may be implemented with a semiconductor compound, for example, a compound semiconductor of group 3-5 or group 2-6, and may be doped with a first conductivity type dopant. For example, when the first conductivity-type semiconductor layer 112 is an n-type semiconductor layer, the n-type dopant may include Si, Ge, Sn, Se, or Te, but is not limited thereto.

The first conductivity-type semiconductor layer 112 is 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, and InP. It can be.

The first conductive semiconductor layer 112 may be formed using a method such as chemical vapor deposition (CVD), molecular beam epitaxy (MBE), sputtering, or hydroxide vapor phase epitaxy (HVPE), but is not limited thereto. .

Next, an active layer 114 may be formed on the first conductivity type semiconductor layer 112 .

In the active layer 114, electrons injected through the first conductivity-type semiconductor layer 112 and holes injected through the second conductivity-type semiconductor layer 116 formed later meet each other, thereby forming an energy band unique to the active layer (light emitting layer) material. It is a layer that emits light with an energy determined by

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.

The active layer 114 may include a quantum well 114W/quantum wall 114B structure. For example, the active layer 114 may be formed in a pair structure of one or more of InGaN/GaN, InGaN/InGaN, GaN/AlGaN, InAlGaN/GaN, GaAs/AlGaAs, InGaP/AlGaP, and GaP/AlGaP, but is limited thereto. It doesn't work.

Hereinafter, technical characteristics of the active layer 114 according to the embodiment will be described in detail with reference to FIG. 7 . As shown in FIG. 7 , the quantum well 114W of the embodiment includes a first quantum well 114W1 on the first conductivity-type semiconductor layer 116 and a second quantum well 114W2 on the first quantum well 114W1. ) may be included.

In the embodiment, the second quantum well 114W2 may be grown at a lower temperature than the growth temperature of the first quantum well 114W1, for example, at about 600°C to 700°C. If the temperature is less than 600°C, crystallinity problems may occur. In addition, a decrease in light output may occur due to a decrease in quality between interfaces, and when the temperature exceeds 700 ° C, the growth temperature condition is similar to that of the first quantum well 114W1, so the indium cluster function may be weakened. Examples are not limited.

In the embodiment, after forming the second quantum well 114W2 to form a uniform indium cluster, a growth stop time of about 2 to 5 minutes may be provided for an annealing effect, but is not limited thereto.

In the embodiment, the second quantum well 114W2 is disposed in contact with the quantum wall 114B, so that there is a gap between the second quantum well 114W2 having a high indium composition and the quantum wall 114B having no or very low indium composition. Indium clusters (C) may be uniformly formed due to a difference in band gap energy (Eg).

The indium composition of the second quantum well 114W2 may be higher than that of the first quantum well 114W1. For example, the first quantum well 114W1 includes In _x Ga _{1 - x} N (provided that 0<x<1), and the composition (x) of indium of the first quantum well 114W1 is about 13% to about 15%, but is not limited thereto.

In addition, the second quantum well 114W2 includes In _y Ga _{1 - y} N (provided that 0<y<1), and the composition (y) of indium of the second quantum well 114W2 is about 18% to about 20%. If the indium composition of the second quantum well 114W2 is less than 18%, a uniform indium cluster may not be formed, and if it exceeds 20%, crystal quality may be deteriorated.

The second quantum well 114W2 may have a thickness of about 5 Å to about 10 Å. When the thickness of the second quantum well 114W2 is less than 5 Å, indium clusters may not be formed in the second quantum well 114W2. output may decrease.

In an embodiment, the second quantum well 114W2 includes an indium cluster C, and the thickness of the indium cluster C may be greater than or equal to the thickness of the second quantum well 114W2. For example, the size of the indium cluster (C) may be about 10 Å to about 15 Å. When the size of the indium cluster (C) is less than 10 Å, a uniform carrier distribution may not be formed, and when the size exceeds 15 Å, agglomeration may occur in the InGaN-based quantum well, resulting in reduced light output.

According to the embodiment, a uniform indium cluster (C ), it is possible to improve the droop phenomenon along with the improvement of light output by forming a uniform electric potential distribution and remarkably increasing the internal quantum efficiency (IQE).

Referring back to FIG. 6 , the electron blocking layer 118 is formed on the active layer 114 to serve as an electron blocking and cladding (MQW cladding) of the active layer 114 to improve luminous efficiency. can

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.

In an embodiment, the electron blocking layer 118 is implanted in a p-type ion to effectively block overflowing electrons and increase hole injection efficiency.

Next, a second conductivity type semiconductor layer 116 may be formed on the electron blocking layer 118 .

The second conductivity-type semiconductor layer 116 may be formed of a semiconductor compound. For example, the second conductivity type semiconductor layer 116 may be implemented with a compound semiconductor such as group 3-5 or group 2-6, and may be doped with a second conductivity type dopant.

The second conductivity type semiconductor layer 116 is a group 3-group 5 compound semiconductor doped with a second conductivity type dopant, for example, In _x Al _y Ga _{1 -x- y} N (0≤x≤1, 0≤y ≤1, 0≤x+y≤1) may include a semiconductor material having a composition formula. 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.

The second conductivity-type semiconductor layer 116 is a non-cetyl cycle containing p-type impurities such as trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and magnesium (Mg) in a chamber. A p-type GaN layer may be formed by implanting pentadienyl magnesium (EtCp ₂ Mg) {Mg(C ₂ H ₅ C ₅ H ₄ ) ₂ }, but is not limited thereto.

In an embodiment, the first conductivity-type semiconductor layer 112 may be implemented as an n-type semiconductor layer, and the second conductivity-type semiconductor layer 116 may be implemented as a p-type semiconductor layer, but is not limited thereto. In addition, a semiconductor having a polarity opposite to that of the second conductivity type, for example, an n-type semiconductor layer (not shown) may be formed on the second conductivity type semiconductor layer 116 . Accordingly, the light emitting structure layer 110 may be implemented with 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.

Next, as shown in FIG. 8 , components disposed on the upper side of the first conductivity-type semiconductor layer 112 may be partially removed so that a portion thereof is exposed. This process may be performed by wet etching or dry etching, but is not limited thereto.

After that, a current blocking layer 130 may be formed at a location where the second electrode 152 is to be formed.

The current blocking layer 130 may include a non-conductive region, a first conductivity-type ion implantation layer, a first conductivity-type diffusion layer, an insulating material, an amorphous region, and the like.

Next, a light-transmitting electrode layer 140 may be formed on the second conductivity-type semiconductor layer 116 on which the current blocking layer 130 is formed. The light-transmitting electrode layer 140 may include an ohmic layer, and may be formed by stacking a single metal, a metal alloy, or a metal oxide in multiple layers so as to efficiently inject holes.

For example, the light-transmitting electrode layer 140 may be formed of a material having excellent electrical contact with a semiconductor. For example, the light-transmitting electrode layer 140 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 including at least one of Hf, but is not limited to these materials.

Thereafter, a passivation layer 160 may be formed of an insulating layer or the like on a side surface of the light emitting structure layer 110 and a portion of the light-transmitting electrode layer 140 . The passivation layer 160 may expose a region where the first electrode 151 is to be formed.

Next, as shown in FIG. 9 , a second electrode 152 is formed on the light-transmitting electrode layer 140 so as to overlap with the current blocking layer 130, and on the exposed first semiconductor layer 112 of the first conductivity type. A light emitting device according to the embodiment may be manufactured by forming the first electrode 151 .

The first electrode 151 or the second electrode 152 is made of titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), tungsten (W), It may be formed of at least one of molybdenum (Mo), but is not limited thereto.

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

10 is a view for explaining a light emitting device package 200 in which a light emitting device according to an embodiment is installed.

The light emitting device package 200 according to the embodiment includes a package body 205, a third electrode layer 213 and a fourth electrode layer 214 installed on the package body 205, and the package body 205. A molding member 230 provided with a light emitting element 100 installed on and electrically connected to the third electrode layer 213 and the fourth electrode layer 214 and a phosphor 232 to surround the light emitting element 100 can include

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 dissipating 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, and a die bonding method.

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

11 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 heat sink 2400, a power supply 2600, an inner case 2700, and a socket 2800. In addition, the lighting device according to the embodiment may further include any one or more 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 an 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 top 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. Thus, the power supply unit 2600 accommodated in the insulation 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 unit 2630, a base 2650, and an extension unit 2670. The inner case 2700 may include a molding part together with the power supply part 2600 therein. The molding part is a part where the molding liquid is hardened, and allows the power supply part 2600 to be fixed inside the inner case 2700 .

Features, structures, effects, etc. 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, and effects illustrated in each embodiment can be combined or modified with respect to other embodiments by those skilled in the art in the field to which the embodiments belong. Therefore, contents related to these combinations and modifications should be construed as being included in the scope of the embodiments.

Although the above has been described centering on the embodiment, this is only an example and does not limit the embodiment, and those skilled in the art in the field to which the embodiment belongs may find various things not exemplified above to the extent that they do not deviate from the essential characteristics of the embodiment. It will be appreciated that variations and applications of branches 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 forth in the appended claims.

Substrate 105, buffer layer 113, light emitting structure layer 110,
A first conductivity type semiconductor layer 112, an active layer 114, a second conductivity type semiconductor layer 116,
electron blocking layer 118, light-transmitting electrode layer 140, current diffusion layer 130,
First electrode 151, second electrode 152

Claims (7)

a first conductivity type semiconductor layer;
an active layer disposed on the first conductivity-type semiconductor layer; and
A second conductivity-type semiconductor layer disposed on the active layer;
The active layer,
a first quantum wall disposed on the first conductivity type semiconductor layer;
a second quantum wall disposed between the first quantum wall and the second conductivity type semiconductor layer;
A quantum well disposed between the first and second quantum walls and in contact with the first and second quantum walls;
The quantum well,
a plurality of second quantum wells disposed between the first and second quantum walls; and
Including a first quantum well disposed between the plurality of second quantum wells,
The composition of indium in the second quantum well is higher than the composition of indium in the first quantum well,
The second quantum well has a thickness of 5 Å (Omstrong) to 10 Å (Omstrong) light emitting device. According to claim 1,
Among the plurality of second quantum wells, a quantum well closest to the first quantum wall is in contact with the first quantum wall, and a quantum well closest to the second quantum wall is in contact with the second quantum wall. According to claim 1,
The first quantum well includes In _x Ga _1-x N (where 0<x<1),
The composition (x) of indium of the first quantum well is 13% to 15%,
The second quantum well includes In _y Ga _1-y N (provided that 0<y<1),
The composition (y) of indium of the second quantum well is 18% to 20% light emitting device. delete According to claim 1,
The second quantum well includes an indium cluster,
A thickness of the indium cluster is greater than or equal to a thickness of the second quantum well. delete delete

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