KR102432225B1 - Light emitting diode, and light system having the same - Google Patents

Abstract

A light emitting device according to an embodiment includes a first conductivity type semiconductor layer, an active layer including a plurality of quantum wells and quantum walls of an InGaN composition on the first conductivity type semiconductor layer, and a second conductivity type semiconductor layer on the active layer Including, in the quantum well, a first quantum well and a second quantum well having a higher indium composition ratio than the first quantum well are alternately arranged.

Description

Light emitting device and lighting system including same {LIGHT EMITTING DIODE, AND LIGHT SYSTEM HAVING THE SAME}

The embodiment relates to a light emitting device and a lighting system including the same, and more particularly, to a light emitting device including a plurality of quantum wells having different indium composition ratios and a method of manufacturing the same.

A light emitting diode is a p-n junction diode with a characteristic of converting electrical energy into light energy, and can be made of compound semiconductors such as Group III and Group V on the periodic table, and realizes various colors by adjusting the composition ratio of the compound semiconductor. This is possible.

When a forward voltage is applied, the electrons of the n-layer and the holes of the p-layer combine to emit energy corresponding to the energy gap between the conduction band and the valance band, and the energy is emitted as light. It becomes a light emitting device.

Nitride semiconductors are receiving great attention in the field of developing 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.

On the other hand, in the active layer from which light is emitted, quantum wells and quantum walls are alternately arranged, but there is a problem in that it is difficult to obtain high-quality thin films due to lattice mismatch between quantum wells and quantum walls, and indium is concentrated in random positions. There is a problem that the carrier is constrained.

An embodiment is to provide a light emitting device, a light emitting device package, and a lighting system with improved carrier confinement efficiency by disposing a plurality of quantum wells having different indium composition ratios.

A light emitting device according to an embodiment includes a first conductivity type semiconductor layer, an active layer including a plurality of quantum wells and quantum walls of an InGaN composition on the first conductivity type semiconductor layer, and a second conductivity type semiconductor layer on the active layer Including, in the quantum well, a first quantum well and a second quantum well having a higher indium composition ratio than the first quantum well are alternately arranged.

The embodiment has an effect of improving light efficiency by increasing carrier confinement efficiency by arranging a plurality of quantum wells having different indium composition ratios.

The embodiment has an effect of solving the problem of confinement of carriers at random positions by increasing carrier confinement efficiency in a quantum well having a high indium composition ratio.

The embodiment has an effect of relieving stress caused by alternately disposing the quantum well and the quantum wall.

1 is a cross-sectional view of a light emitting device according to an embodiment.
2 is a bandgap diagram of a light emitting device according to an embodiment.
3 is a bandgap diagram of a light emitting device according to another exemplary embodiment.
4 is a diagram illustrating bandgap energy of a light emitting device according to an embodiment.
5 is an exemplary diagram of the light emitting intensity of the light emitting device according to the prior art, and FIG. 6 is an exemplary view of the light emission intensity of the light emitting device according to the embodiment.
7 is an exemplary view of the light emitting intensity of the light emitting device according to the prior art, and FIG. 8 is an exemplary view of the light emission intensity of the light emitting device according to the embodiment.
9 is an exemplary diagram of a potential region of a light emitting device according to the prior art, and FIG. 10 is an exemplary diagram of a potential region of a light emitting device according to the embodiment.
11 is an exemplary view of hole concentration of a light emitting device according to the prior art, and FIG. 12 is an exemplary view of hole concentration of a light emitting device according to the embodiment.
13 is a cross-sectional view of a light emitting device package according to an embodiment.
14 and 15 are exploded perspective views illustrating embodiments of a lighting system including a light emitting device according to an embodiment.

In the description of embodiments, each layer (film), region, pattern or structure is “on/over” or “under” the substrate, each layer (film), region, pad or pattern. In the case of being described as being formed on, “on/over” and “under” include both “directly” or “indirectly” formed through another layer. do. In addition, the reference for the upper / upper or lower of each layer will be described with reference to the drawings.

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

Referring to FIG. 1 , the light emitting device 100 according to the embodiment includes a substrate 103 , a buffer layer 105 on the substrate 103 , a first conductive semiconductor layer 112 on the buffer layer 105 , and a first The active layer 114 on the conductive semiconductor layer 112, the second conductive semiconductor layer 116 on the active layer 114, the transmissive electrode 120 on the second conductive semiconductor layer 116, the first conductive The first electrode 131 on the type semiconductor layer 112 and the second electrode 132 on the light-transmitting electrode 120 may be included.

In the active layer 114 , electrons (or holes) injected through the first conductivity type semiconductor layer 112 and holes (or electrons) injected through the second conductivity type semiconductor layer 116 meet each other to form the active layer 114 . It is a layer that emits light due to the difference in the band gap of the energy band according to the material forming the . The active layer 114 may be formed of any one of a single well structure, a multi-well structure, a quantum dot structure, or a quantum wire structure, but is not limited thereto.

The active layer 114 may include a plurality of quantum wells and quantum walls. For example, the active layer 114 includes a quantum wall 114B including a first quantum wall 114B1 and a second quantum wall 114B2 on the first conductivity type semiconductor layer 112 , and a first quantum wall 114B1 . and a quantum well 114W disposed between the second quantum wall 114B2.

In the embodiment, by controlling the concentration of indium in a specific region in the quantum well 114W1, indium is concentrated in a random position so that carriers are not constrained in the specific region, so that luminous efficiency can be improved.

The substrate 103 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. For example, the substrate 103 may include at least one of sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ 0 ₃ . A concave-convex structure may be formed on the substrate 103 , and the cross-section of the concave-convex structure may be circular, oval, or polygonal, but is not limited thereto.

In this case, the buffer layer 105 may be formed on the substrate 103 . The buffer layer 105 may alleviate the lattice mismatch between the material of the light emitting structure and the substrate 103 to be formed later, and the material of the buffer layer may be a group III-5 compound semiconductor, for example, GaN, InN, AlN, InGaN, AlGaN, It may be formed of at least one of InAlGaN and AlInN.

The first conductivity type semiconductor layer 112 may be disposed on the buffer layer 105 . The first conductivity type semiconductor layer 112 is implemented as a group III-V compound semiconductor doped with a first conductivity type dopant, and the first conductivity type semiconductor layer 112 is In _x Al _y Ga _1-xy N (0). ≤x≤1, 0≤y≤1, 0≤x+y≤1). The first conductive semiconductor layer 112a has, for example, a stacked structure of layers including at least one of compound semiconductors such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. may include The first conductivity-type semiconductor layer 112 is an n-type semiconductor layer, and the first conductivity-type dopant is an n-type dopant and includes Si, Ge, Sn, Se, and Te. An electrode may be further disposed on the first conductivity type semiconductor layer 112 .

The first conductivity type semiconductor layer 112 may be disposed on the buried oxide layer 140 . The first conductivity type semiconductor layer 112 is implemented as a group III-V compound semiconductor doped with a first conductivity type dopant. and the first conductivity type semiconductor layer 112 includes a compositional formula of In _x Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). The first conductive semiconductor layer 112 has, for example, a stacked structure of layers including at least one of compound semiconductors such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. may include The first conductivity-type semiconductor layer 112 is an n-type semiconductor layer, and the first conductivity-type dopant is an n-type dopant and includes Si, Ge, Sn, Se, and Te. An electrode may be further disposed on the first conductivity type semiconductor layer 112 .

The second conductivity type semiconductor layer 116 is a semiconductor doped with a second conductivity type dopant, for example, In _x Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) ) including the composition formula. The second conductivity type semiconductor layer 116 may be formed of any one of compound semiconductors such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. The second conductivity-type semiconductor layer 116 is a p-type semiconductor layer, and the second conductivity-type dopant is a p-type dopant and may include Mg, Zn, Ca, Sr, and Ba.

The second conductive semiconductor layer 116 may include a superlattice structure, and the superlattice structure may include an InGaN/GaN superlattice structure or an AlGaN/GaN superlattice structure. The superlattice structure of the second conductivity type semiconductor layer 116 can protect the active layer by spreading the current included in the voltage abnormally.

The light-transmitting electrode 120 may be disposed on the upper surface of the second conductive semiconductor layer 116 . Through this, the light-transmitting electrode 120 may electrically connect the light emitting structure 110 and the second electrode 132 .

The first electrode 131 may be disposed on the first conductivity type semiconductor layer 112a. The first electrode 131 is Cr, V, W, Ti, Zn, Ni, Cu, Al, Au, Mo, Ti/Au/Ti/Pt/Au, Ni/Au/Ti/Pt/Au, Cr/Al At least one selected from /Ni/Cu/Ni/Au may be included.

The second electrode 132 may be disposed on the light-transmitting electrode 120 , and may be connected to an external power source to provide power to the light emitting structure 110 . The second electrode 132 is Cr, V, W, Ti, Zn, Ni, Cu, Al, Au, Mo, Ti/Au/Ti/Pt/Au, Ni/Au/Ti/Pt/Au, Cr/Al At least one selected from /Ni/Cu/Ni/Au may be included.

2 is a bandgap diagram of a light emitting device according to an embodiment.

Referring to FIG. 2 , the active layer 114 may include a plurality of quantum wells and quantum walls. For example, the active layer 114 includes a quantum wall 114B including a first quantum wall 114B1 and a second quantum wall 114B2 on the first conductivity type semiconductor layer 112 , and a first quantum wall 114B1 . and a quantum well 114W disposed between the second quantum wall 114B2.

The quantum well 114W may include a first quantum well 114W1 and a second quantum well 114W2 having different concentrations of indium (In), the first quantum well 114W1 and the second quantum well 114W2. ) may be alternately arranged.

The indium (In) composition ratio of the second quantum well 114W2 may be twice that of the indium (In) composition ratio of the first quantum well 114W1. The width of the first quantum well 114W1 may be 3 nm or more and 3.5 nm or less, and the width of the second quantum well 114W2 may be 0.1 nm or more and 3 nm or less, but is not limited thereto. The indium composition ratio of the first quantum well 114W1 may be 10%, and the indium composition ratio of the second quantum well 114W2 may be 20%.

That is, it helps carrier confinement in the second quantum well 114W2 in the quantum well 114W1, increases the probability of carriers in the second quantum well 114W2, and promotes radiate recombination to increase luminous efficiency. can be improved

3 is a bandgap diagram of a light emitting device according to another exemplary embodiment.

Referring to FIG. 3 , the active layer 114 may include a plurality of quantum wells and quantum walls. For example, the active layer 114 includes a quantum wall 114B including a first quantum wall 114B1 and a second quantum wall 114B2 on the first conductivity type semiconductor layer 112 , and a first quantum wall 114B1 . and a quantum well 114W disposed between the second quantum wall 114B2.

The quantum well 114W may include a first quantum well 114W1, a second quantum well 114W2, and a third quantum well 114W3 having different concentrations of indium (In), but is not limited thereto. . The first quantum well 114W1 , the second quantum well 114W2 , and the third quantum well 114W3 may be alternately disposed.

The indium (In) composition ratio of the second quantum well 114W2 may be twice that of the indium (In) composition ratio of the first quantum well 114W1. The width of the first quantum well 114W1 may be 3 nm or more and 3.5 nm or less, and the width of the second quantum well 114W2 may be 0.1 nm or more and 3 nm or less, but is not limited thereto. The indium composition ratio of the first quantum well 114W1 may be 10%, and the indium composition ratio of the second quantum well 114W2 may be 20%.

The indium (In) composition ratio of the third quantum well 114W3 may be 1.5 times the indium composition ratio of the first quantum well 114W1. The width of the third quantum well 114W3 may be 0.1 nm or more and 3 nm or less, and the indium composition ratio of the third quantum well 114W3 may be 15%, but is not limited thereto.

That is, the second quantum well 114W2 and the third quantum well 114W3 in the quantum well 114W help carrier confinement, so that the carrier in the second quantum well 114W2 and the third quantum well 114W3 is It is possible to improve the luminous efficiency by increasing the probability of existence and promoting radiate recombination.

4 is a diagram illustrating bandgap energy of a light emitting device according to an embodiment.

Referring to FIG. 4 , the bandgap energy according to the position of the light emitting device according to the embodiment of FIG. 2 is shown, and it can be seen that the bandgap energy in the region of 240 nm to 260 nm increases based on the composition ratio of indium.

FIG. 5 is an exemplary view of light emission intensity of a light emitting device according to the related art, and FIG. 6 is an exemplary view of light emission intensity of a light emitting device according to the embodiment.

5 and 6, in the light emitting device according to the embodiment, when a plurality of quantum wells having different indium composition ratios are disposed and the energy is 3 (eV), the prior art (FIG. 5) has a light emission intensity of 7.00E21 , and in Example (FIG. 6), the light emission intensity is 1.10E22, indicating that the light emission intensity is improved by 1.5 times or more.

7 is an exemplary view of the light emitting intensity of the light emitting device according to the prior art, and FIG. 8 is an exemplary view of the light emission intensity of the light emitting device according to the embodiment.

7 and 8, in the light emitting device according to the embodiment, the light emitting device according to the embodiment arranges a plurality of quantum wells having different indium composition ratios, and when the wavelength is 415 (nm), the prior art (Fig. 7) has an emission intensity of 5.60E19, and in Example (FIG. 8), the emission intensity is 8.50E19, indicating that the emission intensity is improved by 1.5 times or more.

9 is an exemplary diagram of a potential region of a light emitting device according to the prior art, and FIG. 10 is an exemplary diagram of a potential region of a light emitting device according to the embodiment.

9 and 10 , it can be seen that in the light emitting device according to the embodiment, a plurality of quantum wells having different indium composition ratios are disposed, so that the potential region in the 240 nm to 260 nm region is partially increased.

11 is an exemplary view of hole concentration of a light emitting device according to the prior art, and FIG. 12 is an exemplary view of hole concentration of a light emitting device according to the embodiment.

11 and 12, in the light emitting device according to the embodiment, the light emitting device according to the embodiment arranges a plurality of quantum wells having different indium composition ratios, so that the hole concentration is improved in the 240 nm to 260 nm region. have.

13 is a cross-sectional view of a light emitting device package according to an embodiment.

The light emitting device package according to the present invention may be equipped with a light emitting device having the structure as described above.

The light emitting device package 200 includes a package body 205 , a third electrode layer 213 and a fourth electrode layer 214 disposed on the package body 205 , and disposed on the package body 205 , The 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 are included.

The package body 205 may be formed of a silicon material, a synthetic resin material, or a metal material, and an inclined surface may be formed around the light emitting device 100 .

The third electrode layer 213 and the fourth electrode layer 214 are electrically isolated 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 heat generated from the light emitting device 100 to the outside. It may also play a role in discharging.

The light emitting device 100 may be disposed on the package body 205 or on the third electrode layer 213 or the fourth electrode layer 214 .

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. In the embodiment, it is illustrated that the light emitting device 100 is electrically connected to the third electrode layer 213 and the fourth electrode layer 214 through a wire, but is not limited thereto.

The molding member 230 may surround the light emitting device 100 to protect the light emitting device 100 . In addition, the molding member 230 may include a phosphor 232 to change the wavelength of light emitted from the light emitting device 100 .

14 and 15 are exploded perspective views illustrating embodiments of a lighting system including a light emitting device according to an embodiment.

14, the lighting device according to the embodiment includes a cover 2100, a light source module 2200, a heat sink 2400, a power supply unit 2600, an inner case 2700, and a socket 2800. may include 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 the light emitting device 100 or the light emitting device package 200 according to the present invention.

15, the lighting device according to the present invention includes a cover 3100, a light source unit 3200, a heat sink 3300, a circuit unit 3400, an inner case 3500, and a socket 3600. can do. The light source unit 3200 may include a light emitting device or a light emitting device package according to an embodiment.

103; Board
105; buffer layer
112; first conductive semiconductor layer
114; active layer
116; Second conductive semiconductor layer
120; light-transmitting electrode
131; first electrode
132; second electrode

Claims (11)

a first conductive semiconductor layer;
an active layer including a plurality of quantum wells and a plurality of quantum walls of an InGaN composition on the first conductive semiconductor layer;
A second conductive type semiconductor layer is included on the active layer,
Each of the plurality of quantum wells includes a first quantum well, a second quantum well having a higher indium composition ratio than the first quantum well, and a first quantum well having a higher indium composition ratio than the first quantum well and a lower indium composition ratio than the second quantum well including 3 quantum wells,
A light emitting device in which the first quantum well, the second quantum well, the first quantum well, the third quantum well and the first quantum well are sequentially disposed in each of the plurality of quantum wells. According to claim 1,
The indium composition ratio of the second quantum well is twice that of the indium composition ratio of the first quantum well. According to claim 1,
The width of the first quantum well is 3 nm or more and 3.5 nm or less,
A width of the second quantum well is 0.1 nm or more and 3 nm or less. According to claim 1,
The indium composition ratio of the first quantum well is 10%, and the indium composition ratio of the second quantum well is 20%. According to claim 1,
A width of the first quantum well is greater than or equal to a width of the second quantum well and a width of the third quantum well, respectively. A lighting system comprising the light emitting device of any one of claims 1 to 5. delete delete delete delete delete

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