KR20140083243A

KR20140083243A - Light emitting device

Info

Publication number: KR20140083243A
Application number: KR1020120152754A
Authority: KR
Inventors: 황정현; 정종필; 강동훈; 나종호
Original assignee: 엘지이노텍 주식회사
Priority date: 2012-12-26
Filing date: 2012-12-26
Publication date: 2014-07-04

Abstract

An embodiment relates to a light emitting device, a method for manufacturing the light emitting device, a light emitting package, and a lighting system. An light emitting device according to an embodiment includes: a first conductivity type semiconductor layer (112); an active layer (114) on the first conductivity type semiconductor layer (112); an undoped nitride semiconductor layer (127) on the active layer (114); and a second conductivity type semiconductor layer (116) on the undoped nitride semiconductor layer (127).

Description

[0001] LIGHT EMITTING DEVICE [0002]

Embodiments relate to a light emitting device, a method of manufacturing a light emitting device, a light emitting device package, and an illumination system.

Light Emitting Device is a pn junction diode whose electrical energy is converted into light energy. It can be produced from compound semiconductor such as group III and group V on the periodic table and by controlling the composition ratio of compound semiconductor, It is possible.

When a forward voltage is applied to the light emitting device, electrons in the n-layer and holes in the p-layer are coupled to emit energy corresponding to the band gap energy of the conduction band and the valance band. Is mainly emitted in the form of heat or light, and when emitted in the form of light, becomes a light emitting element.

For example, nitride semiconductors have received great interest in the development of optical devices and high power electronic devices due to their high thermal stability and wide bandgap energy. Particularly, blue light emitting devices, green light emitting devices, ultraviolet (UV) light emitting devices, and the like using nitride semiconductors have been commercialized and widely used.

The nitride semiconductor light emitting device may be classified into a lateral type light emitting device and a vertical type light emitting device depending on the position of the electrode layer.

A horizontal type light emitting device is formed such that a nitride semiconductor layer is formed on a sapphire substrate and two electrode layers are disposed on the upper side of the nitride semiconductor layer.

The nitride semiconductor light emitting device includes an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer which are organic chemically deposited on a sapphire substrate as a different substrate.

According to the related art, a pit is formed in the active layer growth end like the lower part of the active layer, and a pit is merged in the p-type nitride semiconductor layer.

On the other hand, a pit becomes larger as it goes to a longer wavelength, and this pit causes a light output droop and a leakage current.

Also, in the presence of the pits, the second conductive type doping element, for example, Mg is not doped uniformly, which causes a problem in the uniformity of the operating voltage VF3.

Embodiments provide a light emitting device capable of improving light efficiency, a method of manufacturing a light emitting device, a light emitting device package, and an illumination system.

The light emitting device according to the embodiment includes a first conductive semiconductor layer 112; An active layer 114 on the first conductive semiconductor layer 112; An undoped nitride semiconductor layer 127 on the active layer 114; And a second conductive semiconductor layer (116) on the undoped nitride semiconductor layer (127).

According to embodiments, a light emitting device having improved light efficiency, a method of manufacturing a light emitting device, a light emitting device package, and an illumination system can be provided.

For example, according to the embodiment, since the undoped nitride semiconductor layer is provided between the active layer and the second conductivity type semiconductor layer, the size and density of the pit vary depending on the position at the end of growth of the active layer, The pit can be prevented from being transferred to the second conductivity type semiconductor layer by being blocked by the first nitride semiconductor layer.

In addition, according to the embodiment, since the transition of the pits is prevented in the second conductivity type semiconductor layer, the second conductivity type semiconductor layer is uniformly doped with the second conductivity type semiconductor layer, thereby improving the uniformity of the operation voltage VF3 can do.

In addition, according to the embodiment, inter-diffusion of the second conductive type doping element into the active layer can be prevented by the undoped nitride semiconductor layer, thereby improving the quality of the active layer and increasing the internal light emitting efficiency.

In addition, according to the embodiment, the thickness of the undoped nitride semiconductor layer can be formed as a tunneling tunneling hole, and the current uniformity can be improved by performing current speading.

1 is a cross-sectional view of a light emitting device according to an embodiment.
2 to 5 are process sectional views of a method of manufacturing a light emitting device according to an embodiment.
6 is a cross-sectional view of a light emitting device package according to an embodiment.
7 is an exploded perspective view of a lighting apparatus according to an embodiment.

In the description of the embodiments, it is to be understood that each layer (film), area, pattern or structure may be referred to as being "on" or "under" the substrate, each layer Quot; on "and" under "are intended to include both" directly "or" indirectly " do. Also, the criteria for top, bottom, or bottom of each layer will be described with reference to the drawings.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. Also, the size of each component does not entirely reflect the actual size.

(Example)

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

The light emitting device 100 according to the embodiment includes a first conductive semiconductor layer 112, an active layer 114 on the first conductive semiconductor layer 112, Layer 127 and the second conductive semiconductor layer 116 on the undoped nitride semiconductor layer 127. [

The first conductive semiconductor layer 112, the active layer 114, and the second conductive semiconductor layer 116 may form the light emitting structure 110. In this case,

In an embodiment, the undoped nitride semiconductor layer 127 may include an undoped GaN layer, but the present invention is not limited thereto.

The embodiment may further include a second conductivity type gallium nitride based layer 128 on the undoped nitride semiconductor layer 127 and the second conductivity type semiconductor layer 116.

According to the embodiment, since the undoped nitride semiconductor layer is provided between the active layer and the second conductivity type semiconductor layer, the size and density of the pit vary depending on the position at the end of the active layer growth, It is possible to prevent the pit from being transferred to the second conductivity type semiconductor layer.

In addition, according to the embodiment, since the transition of the pits is prevented in the second conductivity type semiconductor layer, the second conductivity type semiconductor layer is uniformly doped with the second conductivity type semiconductor layer, thereby improving the uniformity of the operation voltage VF3 can do

In an exemplary embodiment, the undoped nitride semiconductor layer 127 may be formed to a thickness of about 10 Å to about 15 Å.

According to the embodiment, the thickness of the undoped nitride semiconductor layer 127 is about 10 Å or more to prevent interdiffusion of the second conductive type doping element into the active layer, thereby improving the quality of the active layer .

Since the thickness of the undoped nitride semiconductor layer 127 is about 15 angstroms or less, it is possible to tunnel the holes, thereby preventing an increase in the operating voltage VF and contributing to current speading .

Accordingly, the undoped nitride semiconductor layer 127 has a specific effect within a thickness range of about 10 Å to about 15 Å.

According to the embodiment, inter-diffusion of the second conductive type doping element into the active layer can be prevented by the undoped nitride semiconductor layer 127, thereby improving the quality of the active layer and increasing the internal light emitting efficiency .

In addition, according to the embodiment, the thickness of the undoped nitride semiconductor layer 127 may be formed as a tunneling hole to improve current uniformity.

For example, when the p-GaN layer is grown after the active layer is grown, there is a possibility that Mg is interdiffused, which damages the active layer. According to the embodiment, the undoped nitride semiconductor layer When growing, Mg is prevented from entering into the active layer. When grown to a thickness of 10 Å to 15 Å, the hole injection is thinned to prevent tunneling and increase of the operating voltage VF3.

When the pit is grown up to the active layer, it can be seen that V-Pit is formed on the surface, and this pit becomes a mergy on the p-GaN layer side. The uniformity of VF3 tends to be poor. Therefore, the uniformity of VF3 can be improved by inserting the undoped nitride semiconductor layer to keep the pit size constant according to the embodiment.

Hereinafter, a method of manufacturing a light emitting device according to an embodiment will be described with reference to FIGS. 2 to 5. FIG.

2 to 5 illustrate a horizontal light emitting device in which a light emitting device according to an embodiment is grown on a predetermined growth substrate 105. However, the present invention is not limited to this, The present invention can also be applied to a vertical type light emitting device in which electrodes are formed on the exposed first conductive type semiconductor layer.

First, a buffer layer 107 may be formed on the substrate 105 as shown in FIG.

The substrate 105 may be formed of a material having excellent thermal conductivity, or may be a conductive substrate or an insulating substrate. For example, the substrate 105 is a sapphire (Al ₂ O _3), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ 0 ₃ May be used.

The buffer layer 107 may relieve mismatching between the material of the light emitting structure 110 and the substrate 105. The material of the buffer layer 107 may be a Group III-V compound semiconductor such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN.

The buffer layer 107 may be an Al _x Ga _(1-x) N (0 _{? X?} 1) / GaN super lattice layer, but is not limited thereto. When the buffer layer 107 is an Al _x Ga _1-x N (0 _{? X?} 1) / GaN super lattice layer, dislocations caused by lattice mismatch between the material of the light emitting structure and the substrate 105 are more effectively Can be blocked.

In an embodiment, an undoped semiconductor layer 108 may be formed on the buffer layer 107.

Thereafter, the first conductive semiconductor layer 112 is formed on the undoped semiconductor layer 108.

The first conductive semiconductor layer 112 may be formed of a compound semiconductor such as a Group 3-Group-5, Group-6, or the like, and may be doped with a first conductive dopant.

When the first conductive semiconductor layer 112 is an n-type semiconductor layer, the first conductive dopant may include Si, Ge, Sn, Se, and Te as an n-type dopant.

For example, the first conductive semiconductor layer 112 may have a composition formula of In _x Al _y Ga ₁ _-x- _y N (0? X? 1, 0? _Y? 1, 0? _X + And the like. For example, the first conductive semiconductor layer 112 may be formed of one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, But is not limited thereto.

Next, a current diffusion layer 121 may be formed on the first conductive semiconductor layer 112. The current diffusion layer 121 may be an undoped GaN layer but is not limited thereto.

Next, an electron injection layer 123 may be formed on the current diffusion layer 121. The electron injection layer 123 may be a first conductive type gallium nitride layer. For example, the electron injection layer 123 may be an electron injection efficiently by being doped at a concentration of the n-type doping element ^{6.0x10 18 atoms / cm 3 ~ 8.0x10} 18 atoms / cm 3.

Next, a strain control layer (not shown) may be formed on the electron injection layer 123. For example, a strain control layer formed of In _y Al _x Ga _y _(1-xy) N (0? X? 1, 0? _Y? 1) / GaN or the like can be formed on the electron injection layer 123 .

The strain control layer can effectively alleviate the stress that is caused by the lattice mismatch between the first conductive semiconductor layer 112 and the active layer 114.

Further, as the strain control layer is repeatedly laminated in at least six cycles having compositions such as first In _x1 GaN and second In _x2 GaN, more electrons are collected at a low energy level of the active layer 114, The probability of recombination of holes is increased and the luminous efficiency can be improved.

Next, as shown in FIG. 3, the active layer 114 is formed on the strain control layer.

In an embodiment, the active layer 114 may be formed of at least one of a single quantum well structure, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure. have.

For example, the active layer 114 may be formed with a multiple quantum well structure by injecting trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) But is not limited thereto.

The well layer / barrier layer of the active layer 114 may be formed of any one or more pairs of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP But is not limited thereto. The well layer may be formed of a material having a band gap lower than the band gap of the barrier layer.

Next, in the embodiment, the undoped nitride semiconductor layer 127 may be formed on the active layer 114.

Accordingly, according to the embodiment, the thickness of the undoped nitride semiconductor layer 127 is set to about 10 Å or more to prevent interdiffusion of the second conductive type doping element into the active layer, Since the layer 127 has a thickness of about 15 ANGSTROM or less, it is possible to tunnel the holes to contribute to current speading. Accordingly, the undoped nitride semiconductor layer 127 has a specific effect within a thickness range of about 10 Å to about 15 Å.

Next, a second conductivity type gallium nitride based layer 128 may be formed on the undoped nitride semiconductor layer 127.

According to the embodiment, the second conductivity type gallium nitride based layer 128 is formed to serve as electron blocking and cladding of the active layer (MQW cladding), thereby improving the luminous efficiency.

For example, the second conductivity type gallium nitride based layer 128 may be formed of a semiconductor of Al _x In _y Ga _(1-xy) N (0? _X _{? 1, 0?} _Y _{? 1} ) The active layer 114 may have an energy band gap higher than the energy band gap of the active layer 114 and may be formed to a thickness of about 100 Å to about 600 Å.

In addition, the second conductivity type gallium nitride based layer 128 may be formed of a superlattice of Al _z Ga _(1-z) N / GaN (0? _Z ? 1), but is not limited thereto.

The second conductivity type gallium nitride based layer 128 can effectively block electrons that are ion-implanted into the p-type and overflow, and increase the hole injection efficiency. For example, the second conductivity type gallium nitride based layer 128 may be doped with Mg to a concentration of about 10 ¹⁸ to 10 ²⁰ / cm ³ to effectively block the electrons that overflow and increase the hole injection efficiency .

Next, a second conductivity type semiconductor layer 116 may be formed on the second conductivity type gallium nitride based layer 128. The second conductive semiconductor layer 116 may be formed of a semiconductor compound. 3-group-5, group-2-group-6, and the like, and the second conductivity type dopant may be doped.

For example, the second conductive semiconductor layer 116 may have a composition formula of In _x Al _y Ga ₁ _-x- _y N (0? X? 1, 0? _Y? 1, 0? _X + And the like. When the second conductive semiconductor layer 116 is a p-type semiconductor layer, the second conductive dopant may include Mg, Zn, Ca, Sr, and Ba as p-type dopants.

In an embodiment, the first conductive semiconductor layer 112 may be an n-type semiconductor layer, and the second conductive semiconductor layer 116 may be a p-type semiconductor layer. Also, on the second conductive semiconductor layer 116, a semiconductor (e.g., an n-type semiconductor) (not shown) having a polarity opposite to that of the second conductive type may be formed. Accordingly, the light emitting structure 110 may have any one of an n-p junction structure, a p-n junction structure, an n-p-n junction structure, and a p-n-p junction structure.

Next, in the embodiment, the light-transmitting electrode 130 is formed on the second conductive type semiconductor layer 116, and the light-transmitting electrode 130 may include a light-transmitting ohmic layer, A single metal, a metal alloy, a metal oxide, or the like may be laminated in multiple layers.

For example, the transmissive electrode 130 may be formed of a material selected from the group consisting of ITO (indium tin oxide), IZO (indium zinc oxide), IZTO (indium zinc tin oxide), IAZO (indium aluminum zinc oxide), IGZO (ZnO), indium gallium tin oxide (AZO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IZON nitride, AGZO ZnO, IrOx, RuOx, and NiO, and is not limited to such a material.

4, the light-transmitting electrode 130, the second conductivity type semiconductor layer 116, the second conductivity type gallium nitride series layer 128, and the first conductivity type semiconductor layer 112 are formed to expose the first conductivity type semiconductor layer 112, A portion of the first conductive type semiconductor layer 112 is exposed by removing a portion of the first conductive type semiconductor layer 127, the active layer 114, the strain control layer, the electron injection layer 123 and the current diffusion layer 121 .

5, a second electrode 132 is formed on the transparent electrode 130, and a first electrode 131 is formed on the exposed first conductive type semiconductor layer 112. Referring to FIG.

6 is a view illustrating a light emitting device package having the light emitting device according to the embodiments.

The light emitting device package according to the embodiment includes a package body 205, a third electrode layer 213 and a fourth electrode layer 214 provided on the package body 205, A light emitting device 100 electrically connected to the third electrode layer 213 and the fourth electrode layer 214 and a molding member 230 surrounding the light emitting device 100 are included.

The package body 205 may be formed of a silicon material, a synthetic resin material, or a metal material, and the 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 provide power to the light emitting device 100. The third electrode layer 213 and the fourth electrode layer 214 may function to increase light efficiency by reflecting the light generated from the light emitting device 100, And may serve to discharge heat to the outside.

The light emitting device 100 may be a horizontal type light emitting device as illustrated in FIG. 1, but is not limited thereto, and a vertical type light emitting device may also be used.

The light emitting device 100 may be mounted 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 a wire, flip chip, or die bonding method. The light emitting device 100 is electrically connected to the third electrode layer 213 through a wire and electrically connected to the fourth electrode layer 214 directly.

The molding member 230 surrounds 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.

A light guide plate, a prism sheet, a diffusion sheet, a fluorescent sheet, and the like, which are optical members, may be disposed on a path of light emitted from the light emitting device package. The light emitting device package, the substrate, and the optical member may function as a backlight unit or function as a lighting unit. For example, the lighting system may include a backlight unit, a lighting unit, a pointing device, a lamp, and a streetlight.

7 is an exploded perspective view of a lighting device having a lighting device according to an embodiment.

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

For example, the cover 2100 may have a shape of a bulb or a hemisphere, and may be provided in a shape in which the hollow is hollow and a part is opened. The cover 2100 may be optically coupled to the light source module 2200 and may be coupled to the heat discharger 2400. The cover 2100 may have an engaging portion that engages with the heat discharging body 2400.

The inner surface of the cover 2100 may be coated with a milky white paint having a diffusion material. The light from the light source module 2200 can be scattered and diffused to emit to the outside using the milky white material.

The cover 2100 may be made of glass, plastic, polypropylene (PP), polyethylene (PE), polycarbonate (PC), or the like. Here, polycarbonate is excellent in light resistance, heat resistance and strength. The cover 2100 may be transparent so that the light source module 2200 is visible from the outside, and may be opaque. The cover 2100 may be formed by blow molding.

The light source module 2200 may be disposed on one side of the heat discharging body 2400. Accordingly, heat from the light source module 2200 is conducted to the heat discharger 2400. The light source module 2200 may include a light emitting device 2210, a connection plate 2230, and a connector 2250.

The member 2300 is disposed on the upper surface of the heat discharging body 2400 and has guide grooves 2310 into which a plurality of illumination elements 2210 and a connector 2250 are inserted. The guide groove 2310 corresponds to the substrate of the illumination device 2210 and the connector 2250.

The surface of the member 2300 may be coated or coated with a white paint. The member 2300 reflects the light reflected by the inner surface of the cover 2100 toward the cover 2100 in the direction toward the light source module 2200. Therefore, the light efficiency of the illumination device according to the embodiment can be improved.

The member 2300 may be made of an insulating material, for example. The connection plate 2230 of the light source module 2200 may include an electrically conductive material. Therefore, electrical contact can be made between the heat discharging body 2400 and the connecting plate 2230. The member 2300 may be formed of an insulating material to prevent an electrical short circuit between the connection plate 2230 and the heat discharging body 2400. The heat discharger 2400 receives heat from the light source module 2200 and heat from the power supply unit 2600 to dissipate heat.

The holder 2500 blocks the receiving groove 2719 of the insulating portion 2710 of the inner case 2700. Therefore, the power supply unit 2600 housed in the insulating portion 2710 of the inner case 2700 is sealed. The holder 2500 has a guide protrusion 2510. The guide protrusion 2510 may have a hole through which the protrusion 2610 of the power supply unit 2600 passes.

The power supply unit 2600 processes or converts an electrical signal provided from the outside and provides the electrical signal to the light source module 2200. The power supply unit 2600 is housed in the receiving groove 2719 of the inner case 2700 and is sealed inside the inner case 2700 by the holder 2500.

The power supply unit 2600 may include a protrusion 2610, a guide 2630, a base 2650, and an extension 2670.

The guide portion 2630 has a shape protruding outward from one side of the base 2650. The guide portion 2630 may be inserted into the holder 2500. A plurality of components may be disposed on one side of the base 2650. The plurality of components may include, for example, a DC converter, a driving chip for controlling driving of the light source module 2200, an ESD (ElectroStatic discharge) protection device for protecting the light source module 2200, The present invention is not limited thereto.

The extension portion 2670 has a shape protruding outward from the other side of the base 2650. The extension portion 2670 is inserted into the connection portion 2750 of the inner case 2700 and receives an external electrical signal. For example, the extension portion 2670 may be provided to be equal to or smaller than the width of the connection portion 2750 of the inner case 2700. The extension 2670 may be electrically connected to the socket 2800 through a wire.

The inner case 2700 may include a molding part together with the power supply part 2600. The molding part is a hardened portion of the molding liquid so that the power supply unit 2600 can be fixed inside the inner case 2700.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects and the like illustrated in the embodiments can be combined and modified by other persons skilled in the art to which the embodiments belong. Accordingly, the contents of such combinations and modifications should be construed as being included in the scope of the embodiments.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. It can be seen that the modification and application of branches are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

The first conductive semiconductor layer 112, the active layer 114,
The undoped nitride semiconductor layer 127, the second conductivity type semiconductor layer 116,

Claims

A first conductive semiconductor layer;
An active layer on the first conductive semiconductor layer;
An undoped nitride semiconductor layer on the active layer; And
And a second conductivity type semiconductor layer on the undoped nitride semiconductor layer.

The method according to claim 1,
And a second conductivity type gallium nitride series layer on the undoped nitride semiconductor layer and the second conductivity type semiconductor layer.

3. The method according to claim 1 or 2,
The above-described undoped nitride semiconductor layer may be formed,
Lt; / RTI > to 15 ANGSTROM.

The method according to claim 1,
And the undoped nitride semiconductor layer includes an undoped GaN layer.