KR102251237B1 - Light emitting device - Google Patents

Abstract

The embodiment relates to a light emitting device. The light emitting device disclosed in the embodiment includes: a first conductivity type semiconductor layer and a second conductivity type semiconductor layer; And an active layer between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer. And an electron blocking layer disposed between the active layer and the second conductive semiconductor layer, the active layer including a plurality of well layers and a plurality of barrier layers, and at least one of the plurality of well layers has a first quantum dot And a band gap of a first region in which the first quantum dots are disposed in the well layer is disposed to be narrower than a band gap of the well layer.

Description

Light emitting device {LIGHT EMITTING DEVICE}

The embodiment relates to a light emitting device.

In general, nitride semiconductor materials including a group V source such as nitrogen (N) and a group III source such as gallium (Ga), aluminum (Al), or indium (In) have excellent thermal stability and direct transition type energy. Since it has a band structure, it is widely used as a nitride-based semiconductor device, for example, a nitride-based semiconductor light emitting device in the ultraviolet region and a material for a solar cell.

Nitride-based materials have a wide energy band gap of 0.7 eV to 6.2 eV, and are widely used as materials for solar cell devices due to their characteristics consistent with the solar spectrum region. In particular, ultraviolet light emitting devices are used in various industrial fields such as curing devices, medical analyzers and treatment devices, sterilization, water purification, and purification systems, and are attracting attention as materials that can be used in general lighting as semiconductor lighting sources in the future.

The embodiment provides a light emitting device having a new active layer well structure.

The embodiment provides a light emitting device in which quantum dots are disposed on at least one or all of a plurality of well layers of an active layer.

The embodiment provides a light emitting device having quantum dots in at least one of a well layer and a barrier layer of an active layer.

The embodiment provides a light emitting device having quantum dots having a uniform indium composition in at least one of a well layer and a barrier layer of an active layer.

The embodiment provides a light emitting device capable of reducing an energy gap between a conduction band and a valence band in a well layer of an active layer.

The embodiment is to provide a light-emitting device, a light-emitting device package, and a lighting system having an active layer with improved internal luminous efficiency.

A light emitting device according to an embodiment includes: a first conductivity type semiconductor layer and a second conductivity type semiconductor layer; An active layer disposed between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer and including a plurality of well layers and a plurality of barrier layers; And an electron blocking layer disposed between the active layer and the second conductive semiconductor layer, wherein at least one of the plurality of well layers includes a first quantum dot, and a first quantum dot is disposed in the well layer. A band gap of one region may be narrower than a band gap of a region other than the first region of the well layer.

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In the light emitting device according to the embodiment, internal quantum efficiency may be improved.

The light emitting device according to the embodiment may improve a phenomenon in which quantum efficiency is deteriorated in a high current mode.

According to the embodiment, the reliability of a light emitting device and a light emitting device package including the same may be improved.

1 is a cross-sectional view of a light emitting device according to an embodiment.
FIG. 2 is a diagram illustrating an active layer in the light emitting device of FIG. 1.
3 is a diagram illustrating a first example of an energy band diagram by quantum dots in the active layer of FIG. 2.
4 is a diagram illustrating a second example of an energy band diagram of an active layer in the light emitting device of FIG. 2.
5 is a partially enlarged view of a well layer of the active layer of FIG. 4.
6 is a diagram illustrating a third example of an energy band diagram of the active layer of FIG. 1.
7 is a diagram illustrating a fourth example of an energy band diagram of the active layer of FIG. 1.
8 is a diagram showing a fifth example of the energy band diagram of the active layer of FIG. 1.
9 and 10 are diagrams illustrating an example of a position change of a quantum dot in a well layer of the active layer of FIG. 2.
11 is an example of arranging electrodes in the light emitting device of FIG. 1.
12 is another example of disposing an electrode in the light emitting device of FIG. 1.
13 is a cross-sectional view of a light emitting device package having a light emitting device according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

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 according to an embodiment, FIG. 2 is a diagram illustrating an active layer in the light emitting device of FIG. 1, and FIG. 3 is a diagram illustrating a first example of an energy band diagram of the active layer of FIG. 2.

1 to 3, the light emitting device according to the embodiment is disposed on the first conductive type semiconductor layer 41, the first conductive type semiconductor layer 41, and the well layer 62 and the barrier layer ( An active layer 51 having 52, an electron blocking layer 71 disposed on the active layer 51, and a second conductive type semiconductor layer 75 disposed on the electron blocking layer 71 may be included. have.

The light emitting device may include one or more or all of a low conductivity layer 33, a buffer layer 31, and a substrate 21 under the first conductivity type semiconductor layer 41.

The light emitting device includes a first cladding layer 43 between the first conductive semiconductor layer 41 and the active layer 51 and a second cladding layer between the active layer 51 and the second conductive semiconductor layer 75 At least one or all of (73) may be included.

The substrate 21 may be, for example, a light-transmitting, conductive or insulating substrate. For example, the substrate 21 may include at least one _{of sapphire (Al 2} O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ O _3. A plurality of protrusions (not shown) may be formed on at least one or both of the upper and lower surfaces of the substrate 21, and each of the plurality of protrusions has a side cross-section, at least one of a hemispherical shape, a polygonal shape, and an elliptical shape And may be arranged in a stripe shape or a matrix shape. The protrusion may improve light extraction efficiency.

A plurality of compound semiconductor layers may be disposed on the substrate 21, and equipment for growing the plurality of compound semiconductor layers includes an electron beam evaporator, physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma laser deposition (PLD). , Dual-type thermal evaporator (dual-type thermal evaporator) sputtering (sputtering), MOCVD (metal organic chemical vapor deposition) may be formed by, but not limited to this.

A buffer layer 31 may be formed between the substrate 21 and the first conductive semiconductor layer 41. The buffer layer 31 may be formed of at least one layer using a Group II to Group VI compound semiconductor. The buffer layer 31 includes a semiconductor layer using a group III-V compound semiconductor, for example, In _x Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y) It can be implemented with a semiconductor material having a composition formula of ≤1). The buffer layer 31 includes, for example, at least one of materials such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP, and ZnO.

The buffer layer 31 may have a super lattice structure in which different semiconductor layers are alternately arranged. The buffer layer 31 may be formed to alleviate a difference in lattice constant between the substrate 21 and the nitride-based semiconductor layer, and may be defined as a defect control layer. The lattice constant of the buffer layer 31 may have a value between the lattice constant between the substrate 21 and the nitride-based semiconductor layer. The buffer layer 31 may not be formed, but is not limited thereto.

The low conductivity layer 33 may be disposed between the buffer layer 31 and the first conductivity type semiconductor layer 41. The low conductivity layer 33 is an undoped semiconductor layer and has an electrical conductivity lower than that of the first conductivity type semiconductor layer 41.

The low-conductivity layer 33 may be implemented as a group II to VI compound semiconductor, for example, a group III-V compound semiconductor, and the undoped semiconductor layer has a first conductivity type characteristic even if it is not intentionally doped with a conductivity type dopant. Will have. The undoped semiconductor layer may not be formed, but is not limited thereto. The low conductivity layer 33 may include, for example, at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. The low conductive layer 33 may not be formed, but is not limited thereto.

The first conductivity type semiconductor layer 41 may be disposed between at least one of the substrate 21, the buffer layer 31, and the low conductivity layer 33 and the active layer 51. The first conductive type semiconductor layer 41 may be implemented with at least one of a group III-V and a group II-VI compound semiconductor doped with a first conductive type dopant.

The first conductive semiconductor layer 41 is _{a semiconductor material having a composition formula of, for example, In x} Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). Can be formed. The first conductive semiconductor layer 41 may include, for example, at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. The first conductive semiconductor layer 41 may be an n-type semiconductor layer doped with an n-type dopant such as Si, Ge, Sn, Se, and Te.

The first conductive semiconductor layer 41 may be disposed as a single layer or multiple layers. The first conductive semiconductor layer 41 may have a superlattice structure in which at least two different layers are alternately arranged. The first conductive semiconductor layer 41 may be an electrode contact layer.

The first cladding layer 43 may be disposed between the first conductive semiconductor layer 41 and the active layer 51. The first cladding layer 43 may contact the first conductive semiconductor layer 41 and the active layer 51. The first cladding layer 43 may include an AlGaN-based semiconductor. The first cladding layer 43 may be a dopant of a first conductivity type, for example, an n-type semiconductor layer having an n-type dopant. The first cladding layer 43 may include at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP, Si, Ge, Sn, Se, Te It may be an n-type semiconductor layer doped with an n-type dopant, such as. The first cladding layer 43 may not be formed.

The active layer 51 may be formed of at least one of a single well, a single quantum well, a multiple well, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure. I can.

In the active layer 51, electrons (or holes) injected through the first conductive semiconductor layer 41 and holes (or electrons) injected through the second conductive semiconductor layer 75 meet each other, and the It is a layer that emits light due to a difference in a band gap of an energy band according to a material for forming the active layer 51.

The active layer 51 may be implemented as a compound semiconductor. The active layer 51 may be implemented as at least one of a group II-VI and a group III-V compound semiconductor, for example.

As shown in FIG. 2, when the active layer 51 is implemented in a multi-well structure, the active layer 51 includes a plurality of well layers 62 and a plurality of barrier layers 52. The well layer 62 and the barrier layer 52 are alternately disposed, and a pair of the well layer 62 and the barrier layer 52 may be formed in 2 to 30 cycles, for example, 2 to 10 cycles.

The cycle of the well layer 62/barrier layer 52 is, for example, InGaN/GaN, GaN/AlGaN, AlGaN/AlGaN, InGaN/AlGaN, InGaN/InGaN, AlGaAs/GaAs, InGaAs/GaAs, InGaP/GaP. , AlInGaP/InGaP, or InP/GaAs pair.

Among the well layer 62 and the barrier layer 52 of the active layer 51, the layer closest to the first conductive type semiconductor layer 41 may be a well layer 62, and the second conductive type semiconductor layer The layer closest to 75 may be the barrier layer 52. The well layer 62 may be disposed between two adjacent barrier layers 52, respectively. The active layer 51 may emit blue, green, red, or ultraviolet wavelengths.

The indium (In) composition of the well layer 62 may have a higher composition than the indium composition of the barrier layer 52. The aluminum composition of the barrier layer 52 has a composition higher than that of the aluminum of the well layer 62. The well layer 62 may be formed of, for example, _{a semiconductor material having a composition formula of In x} Al _y Ga _1-xy N (0<x≤1, 0≤y≤1, 0≤x+y<1). . The barrier layer 52 may be formed of, for example, _{a semiconductor material having a composition formula of In x} Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y<1). . The well layer 62 may not have a composition of aluminum. The barrier layer 52 may not have an indium composition.

As shown in FIG. 2, in the active layer 51 according to the embodiment, quantum dots 50 may be disposed on at least one or all of the plurality of well layers 62. The quantum dot 50 may be provided in a three-dimensional shape, and the three-dimensional shape may be formed in a dome shape, a pyramid shape, a cylindrical shape, a disk shape, or a polygon shape.

The quantum dot 50 may have an indium (In) composition that is four or more times higher than that of the well layer 62, and may include, for example, 80% to 100%. The quantum dots 50 may include InN or InGaN. These quantum dots 50 can confine the injected carriers, so that more carriers can participate than the quantum wells. Accordingly, the internal quantum efficiency of the active layer 51 may be improved.

The electron blocking layer 71 is disposed on the active layer 51 and may have a band gap wider than that of the active layer 51. The electron blocking layer 71 may be formed of a GaN-based semiconductor, for example, an AlGaN-based semiconductor. The electron blocking layer 71 may be disposed on the barrier layer 62 of the active layer 51 and includes a single layer or multilayer structure.

The second cladding layer 73 is disposed on the electron blocking layer 71. The second cladding layer 73 is disposed between the electron blocking layer 71 and the second conductive semiconductor layer 75.

The second cladding layer 73 may include an AlGaN-based semiconductor. The second cladding layer 73 may be a p-type semiconductor layer having a second conductivity-type dopant, for example, a p-type dopant. The second cladding layer 73 may include at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, or AlGaInP, and may include Mg, Zn, Ca, Sr, It may contain a p-type dopant such as Ba. The first cladding layer 73 may not be formed.

The second conductive semiconductor layer 75 may be disposed on the second cladding layer 73. The second conductive semiconductor layer 75 is _{a semiconductor material having a composition formula of, for example, In x} Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). Can be formed. The second conductive semiconductor layer 75 may include, for example, at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, or AlGaInP, and p-type dopant May be a doped p-type semiconductor layer.

The second conductive semiconductor layer 75 may be disposed as a single layer or multiple layers. The second conductive semiconductor layer 75 may have a superlattice structure in which at least two different layers are alternately arranged. The second conductive semiconductor layer 75 may be an electrode contact layer. The second conductive semiconductor layer 75 and the second cladding layer 73 may be formed of an AlGaN-based semiconductor to prevent absorption of ultraviolet wavelengths.

The light emitting structure may include from the first conductive type semiconductor layer 41 to the second conductive type semiconductor layer 75. As another example, in the light emitting structure, the first conductive type semiconductor layer 41 and the first cladding layer 43 are p-type semiconductor layers, and the second cladding layer 73 and the second conductive type semiconductor layer 75 are n It can be implemented as a type semiconductor layer. Such a light emitting structure may be implemented in any one of an np junction structure, a pn junction structure, an npn junction structure, and a pnp junction structure.

Meanwhile, the well layer 62 of the active layer 51 according to the embodiment may be implemented with an InGaN-based semiconductor, for example, InGaN or an InAlGaN semiconductor. The barrier layer 52 may be implemented as a GaN-based semiconductor, for example, InGaN, AlGaN, or InAlGaN semiconductor.

The indium composition of the well layer 62 may range from 4% to 20%, for example, from 10% to 17%. The quantum dot 50 includes an InN or InGaN semiconductor, and the indium composition of the quantum dot 50 may be four or more times higher than the indium composition of the well layer 62, and includes, for example, 80% to 100%. I can. These quantum dots 50 can confine more carriers to be injected, so that more carriers can participate than quantum wells. Accordingly, the internal quantum efficiency of the active layer 51 may be improved.

The width T2 of the quantum dot 50 may be disposed narrower than the thickness T1 of the well layer 62, and includes, for example, a range of 1.5 nm to 2 nm. The width T2 of the quantum dots 50 may be disposed to be 50% or less of the thickness T1 of the well layer 62. When the width T2 of the quantum dot 50 is smaller than or greater than the above range, the thickness T1 of the well layer 62 becomes non-uniform, and thus, the interval between the band gap of the energy band is also non-uniform. Accordingly, carrier recombination efficiency and internal quantum efficiency may be deteriorated.

3 is a first example of a band diagram of the active layer of FIG. 2.

2 and 3, the band gap G2 of the well layer 62 may be narrower than the band gap G1 of the barrier layer 52. A band gap of a region of the well layer 62 in which the quantum dots 50 are disposed may be narrower than the band gap G2 of the well layer 62. The well layer 62 has a uniform distribution below the electron Fermi level (F1) by the quantum dots 50, and thus the gap with the hole Fermi leverl (F2) is further narrowed. I can lose. This can uniformly reduce the gap between the minimum energy of the conduction band and the maximum energy of the valence band. Accordingly, the recombination ratio of the electrons 5 and the holes 6 in the well layer 62 may be increased, and the internal quantum efficiency of the active layer 51 may be improved.

On the other hand, looking at the growing method of the active layer 51, the well layer 62 is grown on the first cladding layer 43 at a first growth temperature. Here, N ₂ may be used as the carrier gas, trimethyl indium (TMIn) and trimethyl gallium (TMGa) may be used as a group III source, and NH ₃ may be used as a group V source. The first growth temperature may be grown at a temperature in the range of 500 degrees to 800 degrees.

When the InN quantum dots 50 are formed on the well layer 62, the supply of the Ga source is stopped at the second growth temperature to form the InN layer for several to tens of seconds. That is, trimethyl indium (TMIn) can be used as a group II member. In this case, since InN has a larger lattice constant than InGaN, the quantum dots 50 of the InN composition having an island shape may be formed by lattice mismatch with InGaN. A plurality of InN quantum dots 50 may be repeatedly arranged in each well layer 62. The second growth temperature may be grown at a temperature lower than the first growth temperature, for example, may be grown in the range of 550 degrees to 650 degrees. In addition, the quantum dots 50 may be grown at a pressure of 200 to 400 mbar.

Here, the quantum dot 50 according to the embodiment may be a self-assembled quantum dot. Looking at the method of forming such spontaneous quantum dots, a layer that grows due to a difference in lattice constant from the base material as the growth thickness increases while progressing two-dimensional growth based on a strong bonding force when the quantum dots having a difference in lattice constant are grown. The internal stress of is also increased, and when the grown layer reaches the critical thickness, it spontaneously forms a three-dimensional island-shaped quantum dot to relieve the stress. The difference in lattice constant for the method of forming such a spontaneous quantum dot may be controlled by the difference in composition content, for example, through the In content. Accordingly, a phase separation phenomenon in the well layer 62 having the quantum dots 50 can be suppressed to prevent the formation of quantum dots having different indium contents. Accordingly, it is possible to improve the luminous efficiency, and it is possible to improve the reduction in quantum efficiency in the high current mode.

In addition, when the quantum dot 50 is formed in the well layer 62, the barrier layer 52 is grown at a third growth temperature. At this time, the change from the second growth temperature to the third growth temperature is increased step by step. By growing from the second growth temperature to the third growth temperature step by step, while providing a uniform thickness of the well layer 62, it is possible to prevent the shape of the quantum dot 50 from being deformed. Since the quantum dots 50 have a uniform size, it is possible to prevent the internal quantum efficiency from deteriorating in the well layer 62. The barrier layer 52 may _{use N 2} as a carrier gas, trimethyl aluminum (TMAl) and trimethyl gallium (TMGa) as a group III source, and NH ₃ as a group V source. The third growth temperature may be grown at a temperature higher than the first growth temperature, for example, in the range of 800 degrees to 1200 degrees. By gradually changing the change from the second growth temperature to the third growth temperature without rapidly changing it, it is possible to prevent the indium content of the quantum dots 50 in each well layer 62 from being different from each other.

By repeating this process, the barrier layer 52 and the well layer 62 are repeatedly grown, and a quantum dot 50 may be formed in the well layer 62. Since the quantum dot 50 may be InGaN or InN, indium may have a composition ranging from 80% to 100%. At least one of the well layer 62 and the barrier layer 52 may be provided with an n-type dopant or a p-type dopant, but is not limited thereto.

FIG. 4 is a second example showing a band diagram of the active layer of FIG. 2, and FIG. 5 is a view showing a partial enlarged view of a well layer of the active layer of FIG. 4. In describing FIGS. 4 and 5, the description of FIGS. 1 and 2 will be referred to. Hereinafter, for convenience of description, a quantum dot is shown on a band diagram to be described.

4 and 5, the active layer 51 includes a well layer 62 having quantum dots 50 and a barrier layer 52 adjacent to the well layer 62. The quantum dots 50 may have a uniform size and may be disposed at a predetermined position. Accordingly, each of the well layers 62 may have a quantum dot 50 disposed in a center region. In the first region 55 in which the quantum dots 50 are disposed, a band gap G3 may be disposed to be narrower than a band gap G2 of the well layer 62. Due to the structure of the well layer 62 having the quantum dots 50, the well trap efficiency of the injected carrier may be increased, and thus the light intensity may be improved. In addition, since the volume of each well structure is increased by the first region 55, the receiving capacity of the carrier can be improved.

The quantum dots 50 may be disposed on each of the plurality of well layers 62, but the embodiment is not limited thereto. One or a plurality of quantum dots 50 arranged in the thickness direction of the active layer 51 in each of the well layers 62 are not limited thereto.

6 is a third example showing a band diagram of the active layer of FIG. 1. In describing FIG. 6, the description of FIGS. 1 and 2 will be referred to. In describing FIG. 6, the description of FIGS. 1 and 2 will be referred to. Hereinafter, for convenience of description, a quantum dot is shown on a band diagram to be described.

Referring to FIG. 6, the active layer 51 includes a plurality of well layers 62 and a plurality of barrier layers 52. Any one of the plurality of well layers 62, for example, the first well layer W1 may have a quantum dot 50. The first well layer W1 having the quantum dots 50 may be disposed closest to the electron blocking layer 71 among the plurality of well layers 62. A first barrier layer B1 may be disposed between the first well layer W1 and the electron blocking layer 71. By disposing the quantum dots 50 in the first well layer W1, the well trapping efficiency of the carrier may be increased, and thus the probability of recombination of electrons and holes in the first well layer W1 may be improved.

In addition, the quantum dots 50 may be disposed on the first well layer W1 closest to the electron blocking layer 71, and the other well layers may not have quantum dots. In the first well layer W1, the volume of the well structure may be increased, so that a carrier capacity may be increased, and a recombination ratio of holes and electrons may be improved.

7 is a fourth example showing a band diagram of the active layer of FIG. 1. In describing FIG. 7, the description of FIGS. 1 and 2 will be referred to. In describing FIG. 7, the description of FIGS. 1 and 2 will be referred to. Hereinafter, for convenience of description, a quantum dot is shown on a band diagram to be described.

Referring to FIG. 7, the active layer 51 includes a plurality of well layers 62 and a plurality of barrier layers 52. At least one of the plurality of well layers 62 may have, for example, a first well layer W1 having a quantum dot 50. In addition, the first well layer W1 is a layer closest to the electron blocking layer 71 or the second conductive semiconductor layer 75, and other well layers may not have quantum dots.

At least one of the plurality of barrier layers 52, for example, the first barrier layer B1 may have a quantum dot 60, and other barrier layers may not have a quantum dot. The indium composition of the quantum dots 60 disposed on the first barrier layer B1 may be less than or equal to the indium composition of the well layer 62. The quantum dots 50 disposed on the first well layer W1 and the quantum dots 60 disposed on the first barrier layer B1 may be divided into first and second quantum dots.

The first well layer W1 having the first quantum dot 50 may be disposed closer to the electron blocking layer 71 than the first conductive semiconductor layer 41, for example, among the plurality of well layers 62 It may be disposed closest to the electron blocking layer 71 or the second conductive semiconductor layer 75.

The first barrier layer B1 having the second quantum dot 60 may be disposed closer to the electron blocking layer 71 than the first conductive semiconductor layer 41 and the first well layer W1, for example. It may be disposed closest to the electron blocking layer 71 among the plurality of barrier layers 52.

The band gap G3 of the first region 55 by the first quantum dots 50 disposed on the first well layer W1 is disposed to be narrower than the band gap G2 of the first well layer W1. I can. That is, since the distance between the conduction band and the valence band may become close, the probability of recombination of holes and electrons may be improved.

In addition, in the second region 65 in which the second quantum dot 60 of the first barrier layer B1 is disposed, the band gap G4 is the band gap G1 of the first barrier layer B1 and the first well. There is a gap between the band gap G2 of the layer W1. Accordingly, the injection efficiency of holes injected into the p-type semiconductor layer can be improved, and electrons can be effectively trapped by the first well layer W1. The internal quantum efficiency of the active layer 51 may be improved.

8 is a fifth example of an energy band diagram of the active layer of FIG. 1. In describing FIG. 8, the description of FIGS. 1 and 2 will be referred to. In describing FIG. 8, the description of FIGS. 1 and 2 will be referred to. Hereinafter, for convenience of description, a quantum dot is shown on a band diagram to be described.

Referring to FIG. 8, the active layer 51 includes a plurality of well layers 62 and a plurality of barrier layers 52. At least one of the plurality of well layers 62 may have, for example, a first well layer W1 having a first quantum dot 50. At least two of the plurality of barrier layers 52 may have, for example, the first and second barrier layers B1 and B2 having a second quantum dot 60.

The first and second barrier layers B1 and B2 may be disposed adjacent to the electron blocking layer 71 rather than the first conductive semiconductor layer 41. The first well layer W1 may be disposed between or directly contact the first and second barrier layers B1 and B2.

The first well layer W1 having the first quantum dot 50 may be disposed closer to the electron blocking layer 71 than the first conductive semiconductor layer 41, for example, among the plurality of well layers 62 It may be disposed closest to the electron blocking layer 71. The band gap G3 of the first region 55 by the first quantum dots 50 disposed on the first well layer W1 is disposed to be narrower than the band gap G2 of the first well layer W1. I can. That is, since the distance between the conduction band and the valence band may become close, the probability of recombination of electrons and holes may be improved.

The first and second barrier layers B1 and B2 trap electrons, and some of the holes injected by the first and second barrier layers B1 and B2 having the first quantum dot 50 are a first well It may be injected beyond the layer W1 to the second well layer W2. Accordingly, electrons and holes may be recombined in the first and second well layers W1 and W2, so that light extraction efficiency may be improved.

9 and 10 are diagrams illustrating an example of changing a position of a quantum dot in a well layer of an active layer according to an embodiment.

9 and 1, at least one of the plurality of well layers 62 includes a quantum dot 50, and the first region 54 in which the quantum dot 50 is disposed is the well layer 62 ) May be disposed adjacent to or in direct contact with the third barrier layer B3 close to the first conductive semiconductor layer 41 among the third and fourth barrier layers B3 and B4 adjacent thereto. The third barrier layer B3 may be disposed closer to the first conductive semiconductor layer 41, for example, an n-type semiconductor layer than the fourth barrier layer B4. Accordingly, the hole injection efficiency in the well layer 62 may be increased. The first region 54 may be disposed closer to the first conductive semiconductor layer 41, for example, an n-type semiconductor layer, than the center of the well layer 62 among the regions within the well layer 62.

As shown in FIG. 10, at least one of the well layers 62 of the active layer includes a quantum dot 50, and the first area 56 in which the quantum dots 50 are disposed is the first area within the well layer 62 area. Among the third and fourth barrier layers B3 and B4, they may be disposed adjacent to or in direct contact with the fourth barrier layer B4. The first region 56 of the well layer 62 is closer to the fourth barrier layer B4 than the third barrier layer B3, for example, the second conductive semiconductor layer 75, for example, a p-type semiconductor layer. Can be placed close to. The first region 56 may be disposed closer to the second conductive semiconductor layer 75, for example, a p-type semiconductor layer, than the center of the well layer 62 among the regions within the well layer 62. The well layer 62 may increase the electron trap rate.

The well layer 62 shown in FIGS. 9 and 10 may be selectively applied to a well layer having quantum dots disclosed in FIGS. 4, 6, 7, and 8 according to an exemplary embodiment.

11 shows an example in which electrodes are disposed in the light emitting device of FIG. 1. In describing FIG. 11, the same parts as those of the above-described configuration will be referred to the description of the above-described embodiment.

Referring to FIG. 11, the light emitting device 101 includes a first electrode 91 and a second electrode 95. The first electrode 91 may be electrically connected to the first conductive semiconductor layer 41, and the second electrode 95 may be electrically connected to the second conductive semiconductor layer 75. The first electrode 91 may be disposed on the first conductive type semiconductor layer 41, and the second electrode 95 may be disposed on the second conductive type semiconductor layer 75.

The first electrode 91 and the second electrode 95 may further have a current diffusion pattern having an arm structure or a finger structure. The first electrode 91 and the second electrode 95 may be made of a metal having characteristics of ohmic contact, an adhesive layer, and a bonding layer, and may be non-transmissive, but are not limited thereto. The first electrode 93 and the second electrode 95 are Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co, Ni, Si, Ge, Ag, and Au, and their selection Can be selected from among the alloys.

An electrode layer 93 may be disposed between the second electrode 95 and the second conductive semiconductor layer 75, and the electrode layer 93 is a translucent material that transmits 70% or more of light or 70% or more of light. It may be formed of a material having a reflective property that reflects, for example, a metal or a metal oxide. The electrode layer 93 includes indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), and indium gallium tin oxide (IGTO). ), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), ZnO, IrOx, RuOx, NiO, Al, Ag, Pd, Rh, Pt, Ir.

An insulating layer 81 may be disposed on the electrode layer 93. The insulating layer 81 may be disposed on an upper surface of the electrode layer 93 and a side surface of the semiconductor layer, and may selectively contact the first and second electrodes 91 and 95. The insulating layer 81 includes an insulating material or insulating resin formed of at least one of oxides, nitrides, fluorides, and sulfides having at least one of Al, Cr, Si, Ti, Zn, and Zr. The insulating layer 81 may be selectively formed from _{, for example, SiO 2} , Si ₃ N ₄ , Al ₂ O ₃ , and TiO _2. The insulating layer 81 may be formed as a single layer or multiple layers, but is not limited thereto.

The embodiment aims to provide a light emitting device capable of increasing internal luminous efficiency by improving carrier trapping efficiency by reducing diffraction of wave functions of electrons and holes in the active layer 51. According to the embodiment, by increasing the overlap ratio of the wave function of electrons and the wave function of holes in the well layer of the active layer, it is possible to increase the internal luminous efficiency by improving the radial recombination rate. .

12 is a diagram illustrating an example of a vertical light emitting device using the light emitting device of FIG. 1. In describing FIG. 12, the same parts as those of the above-described configuration will be referred to the description of the above-described embodiment.

Referring to FIG. 12, the light emitting device 102 includes a plurality of conductive layers 96, 97, 98 under the first electrode 91 and the second conductive semiconductor layer 75 on the first conductive semiconductor layer 41. , 99).

The second electrode is disposed under the second conductive semiconductor layer 75 and includes a contact layer 96, a reflective layer 97, a bonding layer 98, and a support member 99. The contact layer 96 is in contact with a semiconductor layer, for example, a second conductive semiconductor layer 75. The contact layer 96 may be a low-conductivity material such as ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, or a metal of Ni or Ag. A reflective layer 97 is disposed under the contact layer 96, and the reflective layer 97 is composed of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, and combinations thereof. It may be formed in a structure including at least one layer made of a material selected from the group. The reflective layer 97 may be in contact under the second conductive type semiconductor layer 75, but the embodiment is not limited thereto.

A bonding layer 98 is disposed under the reflective layer 97, and the bonding layer 98 may be used as a barrier metal or a bonding metal, and the material is, for example, Ti, Au, Sn, Ni, Cr, It may contain at least one of Ga, In, Bi, Cu, Ag, and Ta and an optional alloy.

A channel layer 83 and a current blocking layer 85 are disposed between the second conductive semiconductor layer 75 and the second electrode.

The channel layer 83 is formed along the bottom edge of the second conductive semiconductor layer 75 and may be formed in a ring shape, a loop shape, or a frame shape. The channel layer 83 includes a transparent conductive material or an insulating material, for example ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, SiO ₂ , SiO _x , SiO _x N _y , Si ₃ N ₄ , Al ₂ O ₃ It may include at least one of TiO _2. An inner portion of the channel layer 163 is disposed under the second conductive semiconductor layer 75, and an outer portion is disposed further outside a side surface of the light emitting structure.

The current blocking layer 85 may be disposed between the second conductive semiconductor layer 75 and the contact layer 96 or the reflective layer 97. The current blocking layer 85 includes an insulating material, and may include, for example, at least one of _{SiO 2} , SiO _x , SiO _x N _y , Si ₃ N ₄ , Al ₂ O ₃ , and TiO _2. As another example, the current blocking layer 85 may also be formed of a metal for Schottky contact.

The current blocking layer 161 is disposed to correspond to the first electrode 181 disposed on the light emitting structure 150A and the light emitting structure 150A in a thickness direction. The current blocking layer 161 may block the current supplied from the second electrode 170 and diffuse it to another path. One or more current blocking layers 85 may be disposed, and at least a part or all of the first electrode 91 may overlap with each other in a vertical direction.

A support member 99 is formed under the bonding layer 98, and the support member 99 may be formed of a conductive member, and the material is copper (Cu-copper), gold (Au-gold), nickel It may be formed of a conductive material such as (Ni-nickel), molybdenum (Mo), copper-tungsten (Cu-W), and a carrier wafer (eg, Si, Ge, GaAs, ZnO, SiC, etc.). As another example, the support member 99 may be implemented as a conductive sheet.

Here, the substrate of FIG. 1 may be removed. The substrate removal method may be removed by a physical method (eg, laser lift off) or/or a chemical method (such as wet etching), and exposes the first conductive type semiconductor layer 41. The first electrode 91 is formed on the first conductive type semiconductor layer 41 by performing isolation etching through the direction in which the substrate is removed.

A light extraction structure (not shown) such as roughness may be formed on the upper surface of the first conductive semiconductor layer 41. An insulating layer (not shown) may be further disposed on the surface of the semiconductor layer, but the embodiment is not limited thereto. Accordingly, the light-emitting device 102 having a vertical electrode structure having a first electrode 91 on the light-emitting structure and a support member 99 under the light-emitting structure can be manufactured.

The embodiment aims to provide a light emitting device capable of increasing internal luminous efficiency by improving carrier trapping efficiency by reducing diffraction of wave functions of electrons and holes in the active layer 51. According to the embodiment, by increasing the overlap ratio of the wave function of electrons and the wave function of holes in the well layer of the active layer, it is possible to increase the internal luminous efficiency by improving the radial recombination rate. .

<Light-emitting device package>

13 is a diagram illustrating a light emitting device package having the light emitting device of FIG. 11.

13, the light emitting device package 200 includes a body 221, a first lead electrode 211 and a second lead electrode 213 disposed at least in part on the body 221, and the body ( And the light emitting device 101 electrically connected to the first lead electrode 211 and the second lead electrode 213 on 221.

The body 221 may be formed of a silicon material, a synthetic resin material, or a metal material. When viewed from above, the body 221 may be formed with a cavity 225 inside and a surface inclined with respect to the cavity bottom around the cavity 225.

The first lead electrode 211 and the second lead electrode 213 are electrically separated from each other, and may be formed to penetrate the inside of the body 221. That is, a part of the first lead electrode 211 and the second lead electrode 213 may be disposed inside the cavity 225, and another part may be disposed outside the body 221.

The first lead electrode 211 and the second lead electrode 213 may supply power to the light emitting element 101 and reflect light generated from the light emitting element 101 to increase light efficiency, The heat generated by the light emitting device 101 may be discharged to the outside. The first and second lead electrodes 211 and 213 may be formed of a metal material and are separated by a gap part 223.

The light emitting device 101 may be installed on the body 221 or on the first lead electrode 211 or/and the second lead electrode 213.

The light-emitting element 101 may be connected to the first lead electrode 211 by a first wire 242, and may be connected to the second lead electrode 213 by a second wire 243, but is not limited thereto.

A molding member 231 or a transparent window may be disposed on the cavity 225. The molding member 231 may include a resin material such as silicone or epoxy, and may include a phosphor therein. The phosphor may convert the wavelength of some light emitted from the light emitting device 101. The transparent window may include a glass material, and may be disposed to be spaced apart from the light emitting device 101.

An optical lens may be further disposed on the cavity 225, but the embodiment is not limited thereto.

In the light-emitting device or light-emitting device package according to the embodiment, a plurality of light-emitting devices or light-emitting device packages are arranged on a substrate, 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 or light-emitting device package I can. Such a light-emitting device or a light-emitting device package, a substrate, and an optical member may function as a backlight unit or a lighting unit. For example, the lighting system may include a backlight unit, a lighting unit, an indication device, a lamp, and a street light. .

According to the light emitting device, the light emitting device package, and the lighting system according to the embodiment, it is possible to increase internal luminous efficiency by improving a radial recombination rate.

Features, structures, effects, and the like described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in each embodiment may be combined or modified 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 present invention.

In addition, although the embodiments have been described above, these are only examples and do not limit the present invention, and those of ordinary skill in the field to which the present invention pertains are illustrated above within the scope not departing from the essential characteristics of the present embodiment. It will be seen that various modifications and applications that are not available 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 present invention defined in the appended claims.

21: substrate 31: buffer layer
33: low conductivity layer 41: first conductivity type semiconductor layer
43: first cladding layer 50,60: quantum dots
51: active layer 52, B1, B2, B3, B4: barrier layer
62,W1,W2: well layer 71: electron blocking structure layer
73: second cladding layer 75: second conductive semiconductor layer

Claims (12)

A first conductivity type semiconductor layer and a second conductivity type semiconductor layer;
An active layer disposed between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer and including a plurality of well layers and a plurality of barrier layers;
An electron blocking layer disposed between the active layer and the second conductivity type semiconductor layer;
A first cladding layer disposed between the first conductivity type semiconductor layer and the active layer; And
A second cladding layer disposed between the electron blocking layer and the second conductivity type semiconductor layer,
The plurality of well layers include a first well layer closest to the electron blocking layer,
The first well layer includes a first quantum dot, and the remaining well layers other than the first well layer among the plurality of well layers do not include the first quantum dot,
The plurality of barrier layers include a first barrier layer closest to the electron blocking layer,
The first barrier layer includes a second quantum dot, and the remaining barrier layers other than the first barrier layer among the plurality of barrier layers do not include the second quantum dot,
One region of the first barrier layer not including the second quantum dots has a first energy band gap,
One region of the first well layer not including the first quantum dot has a second energy band gap smaller than the first energy band gap,
The first region in which the first quantum dots are disposed in the first well layer has a third energy band gap smaller than the second energy band gap,
A second region in which the second quantum dots are disposed in the first barrier layer has a fourth energy band gap,
The fourth energy band gap is smaller than the first energy band gap and larger than the second energy band gap. The method of claim 1,
The first area in which the first quantum dots are disposed is disposed in the center area of the first well layer. The method of claim 1,
The first region is a light emitting device disposed adjacent to or in contact with a barrier layer close to the first conductivity type semiconductor layer within the first well layer. The method of claim 1,
The first region is a light emitting device disposed adjacent to or in contact with a barrier layer close to the second conductive semiconductor layer within the well layer. delete delete delete delete delete delete delete delete

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