KR102224164B1 - Light emitting device and lighting system having the same - Google Patents

Abstract

The light emitting device according to the embodiment includes: a first conductivity type semiconductor layer, an active layer disposed on the first conductivity type semiconductor layer and comprising a well layer and a barrier layer, and a second conductivity type semiconductor layer disposed on the active layer; The barrier layer may include a first barrier layer including In, a second barrier layer including Al, and a third barrier layer including In.
In the embodiment, by including In in the barrier layer, there is an effect of reducing polarization with the well layer and reducing lattice mismatch.

Description

Light-emitting device and lighting system having the same {LIGHT EMITTING DEVICE AND LIGHTING SYSTEM HAVING THE SAME}

The embodiment relates to a light emitting device for improving light efficiency.

In general, a light emitting device is a compound semiconductor that converts electrical energy into light energy. It can be produced as a compound semiconductor such as Group III and Group V on the periodic table, and various colors by adjusting the composition ratio of the compound semiconductor. It can be implemented.

When a forward voltage is applied, electrons in the n-layer and holes in the p-layer are combined to emit energy equivalent to the band gap energy of the conduction band and the balance band. Is mainly emitted in the form of heat or light, and becomes a light emitting device when it is radiated in the form of light. For example, nitride semiconductors are attracting great interest in the development of optical devices and high-power electronic devices due to their high thermal stability and wide bandgap energy. In particular, a blue light emitting device, a green light emitting device, and an ultraviolet (UV) light emitting device using a nitride semiconductor have been commercialized and widely used.

In the conventional active layer of the light emitting device, InGaN/GaN are alternately arranged, but the operating voltage due to polarization and lattice mismatch caused by stress between the layer containing In and the layer not containing In. There arises a problem of lowering and lowering the luminous flux.

In order to solve the above problems, an object of the embodiment is to provide a light emitting device for preventing a decrease in operating voltage and a decrease in luminous flux.

In order to achieve the above object, the light emitting device according to the embodiment includes a first conductivity type semiconductor layer, an active layer formed of a well layer and a barrier layer, disposed on the first conductivity type semiconductor layer, and disposed on the active layer. A second conductivity type semiconductor layer; wherein the barrier layer may include a first barrier layer including In, a second barrier layer including Al, and a third barrier layer including In.

In the embodiment, by including In in the barrier layer, there is an effect of reducing polarization with the well layer and reducing lattice mismatch.

In addition, the embodiment has an effect of enhancing the electron injection efficiency by increasing the content of In in the barrier layer in a region adjacent to the p-type semiconductor layer.

In addition, the embodiment has an effect of enhancing the confinement phenomenon of carriers by including Al in the barrier layer.

In addition, in the embodiment, by forming a thicker barrier layer containing Al, there is an effect of more effectively reinforcing the confinement phenomenon of carriers.

In addition, in the embodiment, by disposing a barrier layer containing Al in a plurality of layers, there is an effect that the confinement phenomenon of carriers can be more effectively strengthened.

1 is a cross-sectional view showing a light emitting device according to a first embodiment.
2 is a graph showing an energy band diagram of a light emitting device according to the first embodiment.
3 is a graph showing an energy band diagram of a light emitting device according to a second embodiment.
4 is a graph showing an energy band diagram of a light emitting device according to a third embodiment.
5 is a cross-sectional view showing a light emitting device according to a fourth embodiment.
6 is a graph showing an energy band diagram of a light emitting device according to a fourth embodiment.
7 is a diagram illustrating a light emitting device package in which a light emitting device is installed according to embodiments.
8 is an exploded perspective view of a lighting system according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.

1 is a cross-sectional view showing a light emitting device according to a first embodiment, and FIG. 2 is a graph showing an energy band diagram of a light emitting device according to the first embodiment.

1 and 2, the light emitting device according to the first embodiment includes a substrate 110, a buffer layer 120 disposed on the substrate 110, and a first light emitting device disposed on the buffer layer 120. A conductive semiconductor layer 130, an active layer 140 disposed on the first conductive semiconductor layer 130, an electron blocking layer EBL 150 disposed on the active layer 140, and the electrons The second conductivity type semiconductor layer 160 disposed on the blocking layer 150, the translucent electrode layer 170 disposed on the second conductivity type semiconductor layer 160, and the first conductivity type semiconductor layer 130 ) And a second electrode 190 disposed on the light-transmitting electrode layer 190.

The substrate 110 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. For example, the substrate 110 may be formed of at least one _{of sapphire (Al 2} O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ 0 _3.

A buffer layer 120 may be disposed on the substrate 110.

The buffer layer 120 serves to alleviate the lattice mismatch between the material of the light emitting structure and the substrate 110. The buffer layer 120 may include a group 3-5 compound semiconductor. The buffer layer 120 may be formed of at least one of AlN, AlGaN, InAlGaN, and AlInN.

A first conductivity type semiconductor layer 130 may be disposed on the buffer layer 120.

The first conductivity-type semiconductor layer 130 may include, for example, an n-type semiconductor layer. The first conductivity type semiconductor layer 130 may be implemented as a compound semiconductor. The first conductivity-type semiconductor layer 130 may be implemented as, for example, a group II-VI compound semiconductor or a group III-V compound semiconductor.

The first conductivity type semiconductor layer 130 may be implemented as 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).} I can. The first conductivity type semiconductor layer 130 may be selected from, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP, etc., and Si, Ge, Sn, An n-type dopant such as Se or Te may be doped.

An active layer 140 may be disposed on the first conductivity type semiconductor layer 130.

In the active layer 140, electrons (or holes) injected through the first conductivity type semiconductor layer 130 and holes (or electrons) injected through the second conductivity type semiconductor layer 160 meet each other, and the active layer It is a layer that emits light due to a difference in the band gap of the energy band according to the material formed of (140). The active layer 140 may be formed in any one of a single well structure, a multiple well structure, a quantum dot structure, or a quantum wire structure, but is not limited thereto.

The active layer 140 may be implemented as a compound semiconductor. The active layer 140 may be implemented as a group II-VI or III-V compound semiconductor, for example. The active layer 140 may be implemented as 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).} When the active layer 140 is implemented in the multi-well structure, the active layer 140 may be implemented by stacking a plurality of well layers and a plurality of barrier layers. The active layer will be described in detail later with reference to the drawings.

An electron blocking layer (EBL) 150 may be disposed on the active layer 140.

The electron blocking layer 150 serves as electron blocking and MQW cladding of the active layer, thereby improving luminous efficiency. The electron blocking layer 150 may be formed of an Al _x In _y Ga _(1-xy) N (0≤x≤1,0≤y≤1) semiconductor, and is higher than the energy band gap of the active layer 140. It may have an energy band gap, and may be formed to a thickness of about 100 Å to about 600 Å. Alternatively, the electron blocking layer 150 may be formed of an Al _z Ga _(1-z) N/GaN (0≦z≦1) superlattice.

A second conductivity type semiconductor layer 160 may be disposed on the electron blocking layer 150.

The second conductivity-type semiconductor layer 160 may be implemented as, for example, a p-type semiconductor layer. The second conductivity type semiconductor layer 160 may be implemented as a compound semiconductor. The second conductivity-type semiconductor layer 160 may be implemented as, for example, a group II-VI compound semiconductor or a group III-V compound semiconductor.

The second conductivity type semiconductor layer 160 may be implemented as 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).} I can. The second conductivity type semiconductor layer 160 may be selected from, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP, etc., and Mg, Zn, Ca, A p-type dopant such as Sr or Ba may be doped.

The first conductivity-type semiconductor layer 130 may include a p-type semiconductor layer, and the second conductivity-type semiconductor layer 160 may include an n-type semiconductor layer. In addition, a semiconductor layer including an n-type or p-type semiconductor layer may be further formed under the second conductivity-type semiconductor layer 160. Accordingly, the light emitting structure may have at least one of an np, pn, npn, and pnp junction structure.

Doping concentrations of impurities in the first conductivity-type semiconductor layer 130 and the second conductivity-type semiconductor layer 160 may be formed uniformly or non-uniformly. That is, the structure of the light emitting structure may be formed in various ways, but is not limited thereto.

A translucent electrode layer 170 may be disposed on the second conductivity type semiconductor layer 160.

The light-transmitting electrode layer 170 may be multilayered on a single metal, a metal alloy, or a metal oxide so that carrier injection can be performed efficiently. For example, the light-transmitting electrode layer 170 may be formed of a material having excellent electrical contact with a semiconductor, and the light-transmitting electrode layer 170 includes indium tin oxide (ITO), indium zinc oxide (IZO), and indium zinc tin oxide (IZTO). , IAZO(indium aluminum zinc oxide), IGZO(indium gallium zinc oxide), 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 by including at least one of Hf, but is not limited to these materials.

The second electrode 190 is formed on the light-transmitting electrode layer 170, and the first electrode 180 is formed on the first conductivity type semiconductor layer 130 where the upper part is exposed. The first electrode 180 and the second electrode 190 include, for example, Cr, Ti, Ag, Ni, RH, Pd, Ir, Ru, Mg, Zn, Pt, Cu, Au. It may be formed of a metal or alloy containing any one of Hf. Thereafter, manufacturing of the light emitting device may be completed by finally connecting the first electrode 180 and the second electrode 190 to each other.

Meanwhile, as shown in FIG. 2, the active layer 140 according to the first embodiment may include a well layer 142 and a plurality of barrier layers 144 disposed on the well layer 142. .

The well layer 142 may include InGaN. The content of In included in the well layer 142 may be 16% to 18%. The well layer 142 may be smaller than the energy band gap of the first conductivity type semiconductor layer 130. When the first conductivity type semiconductor layer 130 contains In, In The content may be greater than the content of In included in the first conductivity type semiconductor layer 130. The content of In in the well layer 142 may be greater than the content of In in the barrier layer 144 to be described later.

The barrier layer 144 includes a first barrier layer 144a, a second barrier layer 144b disposed on the first barrier layer 144a, and a third barrier layer 144b disposed on the second barrier layer 144b. A barrier layer 144c may be included. The total thickness of the barrier layer 144 may be 50 Å to 80 Å. When the thickness of the barrier layer 144 is 50 Å or less or 80 Å or more, carriers composed of electrons and holes cannot be effectively confined.

The first barrier layer 144a may include In. The first barrier layer 144a may be In _x Ga _1-x N (0<x≤1). The In content of the first barrier layer 144a may be 1% to 5%. The thickness T1 of the first barrier layer 144a may be 10 Å to 30 Å. The energy band gap of the first barrier layer 144a may be smaller than the energy gap of the first conductivity type semiconductor layer 130.

Since the first barrier layer 144a contains In, there is an effect of reducing lattice mismatch with the well layer 142. In addition, since the first barrier layer 144a contains In, the height of the barrier is lowered, thereby enhancing electron injection efficiency.

The second barrier layer 144b may include Al. The second barrier layer 144b may be Al _x Ga _1-x N (0<x≤1). By containing Al in the second barrier layer 144b, the height of the barrier can be increased. The thickness T2 of the second barrier layer 144b may be smaller than the thickness T1 of the first barrier layer 144a. The thickness T2 of the second barrier layer 144b may be 1/2 of the thickness T1 of the first barrier layer 144a. The second barrier layer 144b may be formed to have a minimum thickness to serve as a barrier.

The third barrier layer 144c may include In. The third barrier layer 144c may be In _x Ga _1-x N (0<x≤1). The content of In in the third barrier layer 144c may be the same as the content of In in the first barrier layer 144a. Accordingly, the energy band gap of the third barrier layer 144c may be the same as the energy band gap of the first barrier layer 144a. The thickness T3 of the third barrier layer 144c may be formed equal to the thickness T1 of the first barrier layer 144a.

In the drawing, the well layer and the barrier layer are formed in three pairs, but are not limited thereto and may be formed in three or more pairs.

As described above, the active layer according to the first embodiment includes In in the barrier layer, thereby reducing polarization and reducing lattice mismatch, thereby preventing a decrease in operating voltage and a decrease in luminous flux. have.

In addition, the active layer according to the first embodiment includes Al in the barrier layer, thereby effectively performing a barrier role.

3 is a graph showing an energy band diagram of a light emitting device according to a second embodiment.

Referring to FIG. 3, the active layer 140 according to the second embodiment may include a well layer 142 and a plurality of barrier layers 144 disposed on the well layer 142.

The well layer 142 may include InGaN. The barrier layer 144 includes a first barrier layer 144a, a second barrier layer 144b disposed on the first barrier layer 144a, and a third barrier layer 144b disposed on the second barrier layer 144b. A barrier layer 144c may be included.

The first barrier layer 144a may include In. The first barrier layer 144a may be In _x Ga _1-x N (0<x≤1). The In content of the first barrier layer 144a may be 1% to 5%. The thickness T1 of the first barrier layer 144a may be 10 Å to 30 Å.

Since the first barrier layer 144a contains In, there is an effect of reducing lattice mismatch with the well layer. In addition, since the first barrier layer contains In, there is an effect of lowering the height of the barrier and enhancing the injection efficiency of electrons.

The second barrier layer 144b may include Al. The second barrier layer 144b may be Al _x Ga _1-x N (0<x≤1). By containing Al in the second barrier layer 144b, the height of the barrier can be increased. The thickness T2 of the second barrier layer 144b may be smaller than the thickness T1 of the first barrier layer 144a. The second barrier layer 144b may be formed to have a minimum thickness to serve as a barrier.

The third barrier layer 144c may include In. The third barrier layer 144c may be In _x Ga _1-x N (0<x≤1). The content of In in the third barrier layer 144c may be greater than the content of In in the first barrier layer 144a. The content of In included in the third barrier layer 144c may be 1.5 to 2.5 times the content of In included in the first barrier layer 144a. Accordingly, the energy band gap of the third barrier layer 144c may be formed smaller than the energy band gap of the first barrier layer 144a. The thickness T3 of the third barrier layer 144c may be formed equal to the thickness T1 of the first barrier layer 144a.

The active layer according to the second embodiment has an effect of further improving electron injection efficiency by forming the third barrier layer lower than the energy band gap of the first barrier layer.

4 is a graph showing an energy band diagram of a light emitting device according to a third embodiment.

Referring to FIG. 4, the active layer 144 according to the third embodiment may include a well layer 142 and a plurality of barrier layers 144 disposed on the well layer 142.

The well layer 142 may include InGaN. The barrier layer 144 includes a first barrier layer 144a, a second barrier layer 144b disposed on the first barrier layer 144a, and a third barrier layer 144b disposed on the second barrier layer 144b. A barrier layer 144c may be included.

The first barrier layer 144a may include In. The first barrier layer 144a may be In _x Ga _1-x N (0<x≤1). The In content of the first barrier layer 144a may be 1% to 5%. The thickness T1 of the first barrier layer 144a may be 10 Å to 30 Å.

Since the first barrier layer 144a contains In, there is an effect of reducing lattice mismatch with the well layer 142. In addition, since the first barrier layer 144a contains In, the height of the barrier is lowered, thereby enhancing electron injection efficiency.

The second barrier layer 144b may include Al. The second barrier layer 144b may be Al _x Ga _1-x N (0<x≤1). By containing Al in the second barrier layer 144b, the height of the barrier can be increased. The thickness T2 of the second barrier layer 144b may be larger than the thickness T1 of the first barrier layer 144a.

The third barrier layer 144c may include In. The third barrier layer 144c may be In _x Ga _1-x N (0<x≤1). The content of In in the third barrier layer 144c may be the same as the content of In in the first barrier layer 144a. The thickness T3 of the third barrier layer 144c may be formed equal to the thickness T1 of the first barrier layer 144a.

In the active layer according to the third embodiment, by forming the thickness of the second barrier layer containing Al to be thicker than that of the first and third barrier layers, the confinement effect of the carrier may be further improved.

5 is a cross-sectional view showing a light emitting device according to the fourth embodiment, and FIG. 6 is a graph showing an energy band diagram of the light emitting device according to the fourth embodiment.

5 and 6, the light emitting device according to the fourth embodiment includes a substrate 110, a buffer layer 120 disposed on the substrate 110, and a first light emitting device disposed on the buffer layer 120. A conductive semiconductor layer 130, an active layer 240 disposed on the first conductive semiconductor layer 130, an electron blocking layer 150 disposed on the active layer 240, and the electron blocking layer On the second conductivity type semiconductor layer 160 disposed on 150, the translucent electrode layer 170 disposed on the second conductivity type semiconductor layer 160, and the first conductivity type semiconductor layer 130 And a first electrode 180 disposed on and a second electrode 190 disposed on the translucent electrode layer 170. Here, the configuration except for the active layer 240 is the same as the configuration of the light emitting device according to the first embodiment, and thus is omitted.

The active layer 240 may include a well layer 242 and a plurality of barrier layers 244 disposed on the well layer 242.

The well layer 242 may include InGaN. The barrier layer 244 includes a first barrier layer 244a, a second barrier layer 244b disposed on the first barrier layer 244a, and a third barrier layer 244b disposed on the second barrier layer 244b. A barrier layer 244c, a fourth barrier layer 244d disposed on the third barrier layer 244c, and a fifth barrier layer 244e disposed on the fourth barrier layer 244d. I can.

The first barrier layer 244a may include In. The first barrier layer 244a may be In _x Ga _1-x N (0<x≤1). The In content of the first barrier layer 244a may be 1% to 5%. When the first barrier layer contains In, there is an effect of reducing lattice mismatch with the well layer. In addition, since the first barrier layer contains In, there is an effect of lowering the height of the barrier and enhancing the electron injection efficiency.

The second barrier layer 244b may include Al. The second barrier layer 244b may be Al _x Ga _1-x N (0<x≤1). By containing Al in the second barrier layer 244b, the height of the barrier can be increased.

The third barrier layer 244c may include In. The third barrier layer 244c may be In _x Ga _1-x N (0<x≤1). The content of In in the third barrier layer 244c may be the same as the content of In in the first barrier layer 244a. Alternatively, the content of In in the third barrier layer may be different from the content of In in the first barrier layer.

The fourth barrier layer 244d may include Al. The fourth barrier layer 244d may be Al _x Ga _1-x N (0<x≤1). The Al content of the fourth barrier layer 244d may be the same as the Al content of the second barrier layer 244b. Alternatively, the Al content of the fourth barrier layer 244d may be different from the Al content of the second barrier layer 244e.

The fifth barrier layer 244e may include In. The fifth barrier layer 244e may be In _x Ga _1-x N (0<x≤1). The content of In in the fifth barrier layer 244e may be the same as the content of In in the first barrier layer 244a. The content of In in the fifth barrier layer 244e may be the same as the content of In in the third barrier layer 244c. The content of In in the fifth barrier layer 255e may be the same as that of the first barrier layer 244a and the third barrier layer 244c.

As described above, in the active layer according to the fourth exemplary embodiment, by disposing a plurality of AlGaN barrier layers, it is possible to further enhance the confinement of carriers by AlGaN.

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

The light emitting device package 500 according to the embodiment includes a package body part 505, a third electrode layer 513 and a fourth electrode layer 514 installed on the package body part 505, and the package body part 505. A light-emitting device 100 installed in and electrically connected to the third and fourth electrode layers 513 and 514, and a molding member 530 surrounding the light-emitting device 100 are included.

The third electrode layer 513 and the fourth electrode layer 514 are electrically separated from each other, and serve to provide power to the light emitting device 100. In addition, the third electrode layer 513 and the fourth electrode layer 514 may serve to increase light efficiency by reflecting light generated from the light emitting device 100, and It can also play a role in discharging heat to the outside.

The light emitting device 100 may be electrically connected to the third electrode layer 513 and/or the fourth electrode layer 514 by any one of a wire method, a flip chip method, or a die bonding method.

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

The lighting device according to the embodiment may include a cover 2100, a light source module 2200, a radiator 2400, a power supply unit 2600, an inner case 2700, and a socket 2800. In addition, the lighting device according to the embodiment may further include 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 the embodiment.

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

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

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

Although described above with reference to the drawings and embodiments, those skilled in the art will understand that the embodiments can be variously modified and changed without departing from the technical spirit of the embodiments described in the following claims. I will be able to.

110: substrate 120: buffer layer
130: first conductivity type semiconductor layer 140: active layer
142: well layer 144: barrier layer
150: electron blocking layer 160: second conductivity type semiconductor layer

Claims (11)

A first conductivity type semiconductor layer;
An active layer disposed on the first conductivity type semiconductor layer and comprising a well layer and a barrier layer; And
Including; a second conductivity type semiconductor layer disposed on the active layer,
The barrier layer,
A first barrier layer containing In;
A second barrier layer containing Al and disposed on the first barrier layer; And
Including In and including a third barrier layer disposed on the second barrier layer,
The first and third barrier layers have an energy band gap smaller than that of the first conductivity type semiconductor layer,
The second barrier layer is larger than the energy band gap of the first conductivity type semiconductor layer
The third barrier layer has an energy band gap smaller than that of the first barrier layer,
A light emitting device having a thickness of the first barrier layer equal to that of the third barrier layer and greater than a thickness of the second barrier layer. delete delete The method of claim 1,
A light emitting device, characterized in that the content of In in the first barrier layer is less than the content of In in the third barrier layer. The method of claim 4,
The light emitting device comprising the content of In in the third barrier layer is 1.5 to 2.5 times the content of In in the first barrier layer. delete delete delete The method according to any one of claims 1, 4 and 5,
The well layer contains In,
In the light emitting device contained in the well layer is greater than the content of In contained in the barrier layer. delete A lighting system comprising the light emitting device of any one of claims 1, 4 and 5.

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