KR20140059444A

KR20140059444A - Light emitting device

Info

Publication number: KR20140059444A
Application number: KR1020120125920A
Authority: KR
Inventors: 윤재인; 나종호; 심세환; 홍훈기
Original assignee: 엘지이노텍 주식회사
Priority date: 2012-11-08
Filing date: 2012-11-08
Publication date: 2014-05-16

Abstract

Embodiments relate to a light emitting device, 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; A gallium nitride-based superlattice layer 124 on the first conductive semiconductor layer 112; An active layer 114 on the gallium nitride superlattice layer 124; And a second conductive semiconductor layer 116 on the active layer 114. The gallium nitride superlattice layer 124 may include an undoped layer on the first conductive semiconductor layer 112, ) Gallium nitride superlattice layer 124u and a doped gallium nitride superlattice layer 124d on the undoped gallium nitride superlattice layer 124u.

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 epitaxial structure used in the light emitting device includes an electron injection layer, an active layer, and a hole injection layer, and the active layer is a multiple quantum well structure (MQWs), which is usually composed of a heterojunction of a III-V semiconductor that is not doped.

The light emitting device requires doping in order to make the p-n junction structure, but when the doping region is widened, the film quality of the whole semiconductor is deteriorated and the characteristics of the light emitting device are adversely affected.

Embodiments provide a light emitting device, a method of manufacturing a light emitting device, a light emitting device package, and an illumination system capable of providing a highly efficient light emitting device.

The light emitting device according to the embodiment includes a first conductive semiconductor layer 112; A gallium nitride-based superlattice layer 124 on the first conductive semiconductor layer 112; An active layer 114 on the gallium nitride superlattice layer 124; And a second conductive semiconductor layer 116 on the active layer 114. The gallium nitride superlattice layer 124 may include an undoped layer on the first conductive semiconductor layer 112, ) Gallium nitride superlattice layer 124u and a doped gallium nitride superlattice layer 124d on the undoped gallium nitride superlattice layer 124u.

According to the light emitting device, the method of manufacturing the light emitting device, the light emitting device package, and the illumination system according to the embodiments, the thickness ratio of the undoped region and the doped region is appropriately adjusted for the gallium nitride superlattice layer, thereby improving the overall thin film quality A high-efficiency light emitting device can be provided.

1 is a cross-sectional view of a light emitting device according to an embodiment.
2 is a diagram illustrating a secondary-ion mass spectroscopy (SIMS) analysis of a light-emitting device according to an embodiment.
3 is an energy band diagram portion example of a light emitting device according to an embodiment.
4 is a cross-sectional view of a light emitting device package according to an embodiment.
5 to 7 are views showing a lighting apparatus according to an embodiment.
8 and 9 are views showing another example of the lighting apparatus according to the embodiment.
10 is a perspective view of a backlight unit 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 and a gallium nitride superlattice layer 124 on the first conductive semiconductor layer 112, An active layer 114 on the active layer 124 and a second conductive type semiconductor layer 116 on the active layer 114.

The first conductive semiconductor layer 112 and the active layer 114 and the second conductive semiconductor layer 116 may form a light emitting structure 110, And may be formed on a predetermined substrate 105.

FIG. 2 is a view illustrating a secondary-ion mass spectroscopy (SIMS) analysis of a light emitting device according to an embodiment. FIG. 3 is a diagram illustrating an energy band diagram of a light emitting device according to an embodiment.

Hereinafter, a light emitting device according to an embodiment will be described with reference to FIGS. 1 to 3. FIG.

FIG. 1 illustrates a horizontal light emitting device in which a light emitting device 100 according to an embodiment is grown on a predetermined growth substrate 105, but the present invention is not limited thereto. The present invention is also applicable to a vertical type light emitting device in which electrodes are formed on the first conductivity type semiconductor layer. Hereinafter, an embodiment will be described with reference to Fig. 1, but the embodiment is not limited to a horizontal type light emitting device.

In the light emitting device according to the embodiment, 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 embodiment also includes a buffer layer 107 and / or an undoped semiconductor layer (not shown) on the substrate 105 to alleviate the lattice mismatch between the material of the light emitting structure 110 and the substrate 105 .

For example, the material of the buffer layer 107 may be at least one of Group III-V compound semiconductor such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN, but is not limited thereto.

In an exemplary embodiment, the first conductive semiconductor layer 112 may be formed of a compound semiconductor such as a Group III-V-V, Group-VI-VI, or the like, and may be doped with a first conductive type 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.

The current diffusion layer 121 may be formed on the first conductive semiconductor layer 112, for example, an undoped GaN layer.

The current diffusion layer 121 is formed to have a thickness of about 50 nm to about 200 nm, thereby inducing diffusion of carriers to increase light emission efficiency through uniform injection of carriers.

In addition, the embodiment can efficiently inject electrons by forming the electron injection layer 122, for example, the first conductivity type gallium nitride layer on the current diffusion layer 121.

For example, the electron injection layer 122 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. The electron injection layer 122 is formed to have a thickness of about 10 nm to 100 nm or less, thereby increasing the injection efficiency of carriers.

In addition, in the embodiment, a gallium nitride superlattice layer 124, for example, In _y Al _x Ga _(1-xy) N (0? X? 1, 0? ) / GaN super lattice layer is formed on the active layer 114 to effectively alleviate the stress caused by the lattice mismatch between the first conductivity type semiconductor layer 112 and the active layer 114.

The gallium nitride superlattice layer 124 is repeatedly laminated in at least six cycles having a composition such as a first In _x1 GaN and a second In _x2 GaN so that more electrons are collected at a low energy level of the active layer 114, As a result, the probability of recombination of electrons and holes increases and the luminous efficiency can be improved.

According to the light emitting device and the method of manufacturing the same according to the embodiments, it is possible to improve the overall thin film quality and to provide a high-efficiency light emitting device by appropriately adjusting the thickness ratio of the undoped region and the doped region with respect to the gallium nitride superlattice layer have.

That is, in order to form a pn junction structure in the light emitting device, the doping of the p-type element and the n-type element is required, and in order to form a carrier of high concentration in the intrinsic semiconductor, the degree of doping must be increased. And the strain of the light emitting device is changed, thereby adversely affecting the characteristics of the light emitting device.

Accordingly, in order to improve the light intensity through charge balance matching of the LED device, the concentration of the first conductive type element, for example Si, immediately before the growth of the multiple quantum well is important, The gallium-based superlattice layer 124d is disposed closer to the active layer 114 than the undoped gallium nitride superlattice layer 124u.

Accordingly, in the embodiment, the gallium nitride superlattice layer 124 includes an undoped gallium nitride superlattice layer 124u and the undoped gallium nitride superlattice layer 124i on the first conductivity type semiconductor layer 112, And a doped gallium nitride based superlattice layer 124d on the grating layer 124u.

In the embodiment, the doped gallium nitride-based superlattice layer 124d is formed so that the concentration of the first conductive type element is controlled to 1 × 10 ¹⁸ (atoms / cm ³ ) or more and the injection of carriers (for example, electrons) . For example, in the embodiment, the doped gallium nitride-based superlattice layer 124d may have a concentration of the first conductive type element of 1 × 10 ¹⁸ (atoms / cm ³ ) to 1 × 10 ¹⁹ (atoms / cm ³ ) But is not limited thereto.

On the other hand, in the embodiment, the concentration of the first conductive type element in the undoped gallium nitride superlattice layer 124u may be about 5 × 10 ¹⁷ (atoms / cm ³ ) or less. Although the undoped gallium nitride superlattice layer 124u is not intentionally implanted with n-type ions in the embodiment, the concentration of the undoped gallium nitride superlattice layer 124u is about 5 × 10 ¹⁷ atoms / cm < ³ >) or less, but is not limited thereto.

The carrier injection efficiency is improved by increasing the carrier concentration in the region adjacent to the active layer in order to minimize the inverse effect of the doping while paying attention to the main role of the carrier injection layer according to the embodiment and to improve the doping efficiency of the doped gallium nitride series superlattice layer 124d are minimized to minimize the deterioration of the film quality due to the ion implantation, thereby maintaining a high luminous intensity even at high currents.

For example, the thickness of the doped gallium nitride superlattice layer 124d may be thinner than the undoped gallium nitride superlattice layer 124u. In detail, the thickness of the doped GaN-based superlattice layer 124d is controlled to 10% to 30% of the thickness of the undoped GaN-based superlattice layer 124u, so that the concentration of carriers in the region adjacent to the active layer The carrier injection efficiency can be increased and the region of the doped gallium nitride superlattice layer 124d can be minimized to minimize the deterioration of the film quality due to the ion implantation so that a high luminance can be maintained even at high currents.

For example, if the thickness of the doped gallium nitride superlattice layer 124d exceeds 30% of the thickness of the undoped gallium nitride superlattice layer 124u, the quality of the light emitting device chip may deteriorate due to film quality degradation. Can be degraded.

On the other hand, when the thickness of the doped gallium nitride superlattice layer 124d is less than 10% of the thickness of the undoped gallium nitride superlattice layer 124u, the operating voltage VF3 is increased May cause problems.

For example, in an embodiment, the thickness of the doped gallium nitride based superlattice layer 124d is controlled to be between about 50 nm and about 200 nm, so that as the area of the relatively undoped gallium nitride based superlattice layer 124 increases, The degradation of the film quality due to the implantation is minimized, and a high light intensity can be maintained even at a high current.

detail VF3 (20mA) WD (nm) IV (chip) Reference 2.87 448.4 105.0 Case 2.83 449.0 105.6

Table 1 is a table of device characteristics at a specific wavelength (WD: dominant wavelength) of the light emitting device according to the embodiment and the prior art reference. As a result, the operation voltage VF3 is improved as the luminous intensity is maintained or improved as compared with the prior art.

Next, the active layer 114 is formed on the gallium nitride-based super lattice layer 124.

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 114a and the barrier layer 114b of the active layer 114 are formed of any one of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) But the present invention 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 electron blocking layer 126 is formed on the active layer 114 to serve as electron blocking and cladding of the active layer (MQW cladding), thereby improving the luminous efficiency. For example, the electron blocking layer 126 may be formed of a semiconductor of Al _x In _y Ga _(1-xy) N (0? _X _{? 1, 0?} _Y _{? 1} ) And may have an energy band gap higher than the energy band gap, and may be formed to a thickness of about 100 A to about 600 A, but the present invention is not limited thereto.

In addition, the electron blocking layer 126 may be formed of a superlattice made of Al _z Ga _(1-z) N / GaN (0? _Z ? 1), but is not limited thereto.

The electron blocking layer 126 can efficiently block the electrons that are ion-implanted into the p-type and overflow, and increase the hole injection efficiency. For example, the electron blocking layer 126 may be formed by implanting Mg in a concentration range of about 10 ¹⁸ to 10 ²⁰ / cm ³ to effectively block electrons that overflow and increase the hole injection efficiency.

Thereafter, a second conductive semiconductor layer 116 is formed on the electron blocking layer 126. 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.

The second conductivity type semiconductor layer 116 and the active layer 114 are partially removed to expose the first conductivity type semiconductor layer 112 and then the active layer 114 is formed on the light- And a first electrode 131 is formed on the exposed first conductive semiconductor layer 112. The first electrode 131 is formed on the exposed first conductive semiconductor layer 112,

4 is a view illustrating a light emitting device package 200 having a light emitting device according to embodiments.

The light emitting device package 200 according to the embodiment includes a package body 205, a third electrode layer 213 and a fourth electrode layer 214 provided on the package body 205, a package body 205, And a molding member 230 surrounding the light emitting device 100. The light emitting device 100 is electrically connected to the third electrode layer 213 and the fourth electrode layer 214,

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. Vertical light emitting devices and flip chip light emitting devices 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 the wire 230 and is 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.

5 to 7 are views showing a lighting apparatus according to an embodiment.

FIG. 5 is a perspective view of the illumination device according to the embodiment viewed from above, FIG. 6 is a perspective view of the illumination device shown in FIG. 5, and FIG. 7 is an exploded perspective view of the illumination device shown in FIG.

5 to 7, the lighting apparatus according to the embodiment includes a cover 2100, a light source module 2200, a heat discharger 2400, a power supply unit 2600, an inner case 2700, a socket 2800, . &Lt; / RTI > 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. For example, the cover 2100 may diffuse, scatter, or excite light provided from the light source module 2200. The cover 2100 may be a kind of optical member. The cover 2100 may be coupled to the heat discharging body 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. Milky white paints may contain a diffusing agent to diffuse light. The surface roughness of the inner surface of the cover 2100 may be larger than the surface roughness of the outer surface of the cover 2100. This is for sufficiently diffusing and diffusing the light from the light source module 2200 and emitting it to the outside.

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 an opaque layer 126 and may be opaque so that the light source module 2200 is visible from the outside. 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 source unit 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 through which the plurality of light source portions 2210 and the connector 2250 are inserted. The guide groove 2310 corresponds to the substrate of the light source unit 2210 and the connector 2250.

The surface of the member 2300 may be coated or coated with a light reflecting material. For example, 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 has 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 include, for example, a DC converter for converting AC power supplied from an external power source into DC power, a driving chip for controlling driving of the light source module 2200, an ESD (ElectroStatic discharge) protective device, and the like, but 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. One end of each of the positive wire and the negative wire is electrically connected to the extension portion 2670 and the other end of the positive wire and the negative wire are electrically connected to the socket 2800 .

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.

8 and 9 are views showing another example of the lighting apparatus according to the embodiment.

Fig. 8 is a perspective view of a lighting apparatus according to an embodiment, and Fig. 9 is an exploded perspective view of the lighting apparatus shown in Fig.

8 and 9, the illumination device according to the embodiment includes a cover 3100, a light source portion 3200, a heat sink 3300, a circuit portion 3400, an inner case 3500, and a socket 3600 . The light source unit 3200 may include a light emitting device or a light emitting device package according to the embodiment.

The cover 3100 has a bulb shape and is hollow. The cover 3100 has an opening 3110. The light source unit 3200 and the member 3350 can be inserted through the opening 3110. [

The cover 3100 may be coupled to the heat discharging body 3300 and surround the light source unit 3200 and the member 3350. The light source part 3200 and the member 3350 may be shielded from the outside by the combination of the cover 3100 and the heat discharging body 3300. The coupling between the cover 3100 and the heat discharging body 3300 may be combined through an adhesive, or may be combined by various methods such as a rotational coupling method and a hook coupling method. The rotation coupling method is a method in which the cover 3100 is coupled with the heat discharging body 3300 by the rotation of the cover 3100 in such a manner that the thread of the cover 3100 is engaged with the thread groove of the heat discharging body 3300 In the hook coupling method, the protrusion of the cover 3100 is inserted into the groove of the heat discharging body 3300, and the cover 3100 and the heat discharging body 3300 are coupled.

The cover 3100 is optically coupled to the light source unit 3200. Specifically, the cover 3100 may diffuse, scatter, or excite light from the light emitting device 3230 of the light source unit 3200. The cover 3100 may be a kind of optical member. Here, the cover 3100 may have a phosphor inside / outside or in the inside thereof to excite light from the light source part 3200.

The inner surface of the cover 3100 may be coated with a milky white paint. Here, the milky white paint may include a diffusing agent for diffusing light. The surface roughness of the inner surface of the cover 3100 may be larger than the surface roughness of the outer surface of the cover 3100. This is for sufficiently scattering and diffusing light from the light source part 3200.

The cover 3100 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 3100 may be a transparent material that can be seen from the outside of the light source unit 3200 and the member 3350, and may be an invisible and opaque material. The cover 3100 may be formed, for example, by blow molding.

The light source unit 3200 is disposed on the member 3350 of the heat sink 3300 and may be disposed in a plurality of units. Specifically, the light source portion 3200 may be disposed on at least one of the plurality of side surfaces of the member 3350. The light source unit 3200 may be disposed at the upper end of the member 3350.

In Figure 9, the light source 3200 may be disposed on three of the six sides of the member 3350. However, the present invention is not limited thereto, and the light source portion 3200 may be disposed on all the sides of the member 3350. The light source unit 3200 may include a substrate 3210 and a light emitting device 3230. The light emitting device 3230 may be disposed on one side of the substrate 3210.

The substrate 3210 has a rectangular plate shape, but is not limited thereto and may have various shapes. For example, the substrate 3210 may have a circular or polygonal plate shape. The substrate 3210 may be a printed circuit pattern on an insulator. For example, the substrate 3210 may be a printed circuit board (PCB), a metal core PCB, a flexible PCB, a ceramic PCB . &Lt; / RTI > In addition, a COB (Chips On Board) type that can directly bond an unpackaged LED chip on a printed circuit board can be used.

In addition, the substrate 3210 may be formed of a material that efficiently reflects light, or may be formed of a color whose surface efficiently reflects light, for example, white, silver, or the like. The substrate 3210 may be electrically connected to the circuit unit 3400 housed in the heat discharging body 3300. The substrate 3210 and the circuit portion 3400 may be connected, for example, via a wire. The wire may pass through the heat discharging body 3300 to connect the substrate 3210 and the circuit unit 3400.

The light emitting device 3230 may be a light emitting diode chip that emits red, green, or blue light, or a light emitting diode chip that emits UV light. Here, the light emitting diode chip may be a lateral type or a vertical type, and the light emitting diode chip may emit blue, red, yellow, or green light. .

The light emitting device 3230 may have a phosphor. The phosphor may be at least one of a garnet system (YAG, TAG), a silicate system, a nitride system, and an oxynitride system. Alternatively, the fluorescent material may be at least one of a yellow fluorescent material, a green fluorescent material, and a red fluorescent material.

The heat discharging body 3300 may be coupled to the cover 3100 to dissipate heat from the light source unit 3200. The heat discharging body 3300 has a predetermined volume and includes an upper surface 3310 and a side surface 3330. A member 3350 may be disposed on the upper surface 3310 of the heat discharging body 3300. An upper surface 3310 of the heat discharging body 3300 can be engaged with the cover 3100. The upper surface 3310 of the heat discharging body 3300 may have a shape corresponding to the opening 3110 of the cover 3100.

A plurality of radiating fins 3370 may be disposed on the side surface 3330 of the heat discharging body 3300. The radiating fin 3370 may extend outward from the side surface 3330 of the heat discharging body 3300 or may be connected to the side surface 3330. The heat dissipation fin 3370 may increase the heat dissipation area of the heat dissipator 3300 to improve heat dissipation efficiency. Here, the side surface 3330 may not include the radiating fin 3370.

The member 3350 may be disposed on the upper surface 3310 of the heat discharging body 3300. The member 3350 may be integral with the top surface 3310 or may be coupled to the top surface 3310. The member 3350 may be a polygonal column.

Specifically, the member 3350 may be a hexagonal column. The hexagonal column member 3350 has an upper surface, a lower surface, and six sides. Here, the member 3350 may be a circular column or an elliptic column as well as a polygonal column. When the member 3350 is a circular column or an elliptic column, the substrate 3210 of the light source portion 3200 may be a flexible substrate.

The light source unit 3200 may be disposed on six sides of the member 3350. The light source unit 3200 may be disposed on all six sides and the light source unit 3200 may be disposed on some of the six sides. In Fig. 9, the light source unit 3200 is disposed on three sides of six sides.

The substrate 3210 is disposed on a side surface of the member 3350. The side surface of the member 3350 may be substantially perpendicular to the upper surface 3310 of the heat discharging body 3300. Accordingly, the upper surface 3310 of the substrate 3210 and the heat discharging body 3300 may be substantially perpendicular to each other.

The material of the member 3350 may be a material having thermal conductivity. This is to receive the heat generated from the light source 3200 quickly. The material of the member 3350 may be, for example, aluminum (Al), nickel (Ni), copper (Cu), magnesium (Mg), silver (Ag), tin (Sn) Or the member 3350 may be formed of a thermally conductive plastic having thermal conductivity. Thermally conductive plastics are advantageous in that they are lighter in weight than metals and have unidirectional thermal conductivity.

The circuit unit 3400 receives power from the outside and converts the supplied power to the light source unit 3200. The circuit unit 3400 supplies the converted power to the light source unit 3200. The circuit unit 3400 may be disposed on the heat discharging body 3300. Specifically, the circuit unit 3400 may be housed in the inner case 3500 and stored in the heat discharging body 3300 together with the inner case 3500. The circuit portion 3400 may include a circuit board 3410 and a plurality of components 3430 mounted on the circuit board 3410.

The circuit board 3410 has a circular plate shape, but is not limited thereto and may have various shapes. For example, the circuit board 3410 may be in the shape of an oval or polygonal plate. Such a circuit board 3410 may be one in which a circuit pattern is printed on an insulator. The circuit board 3410 is electrically connected to the substrate 3210 of the light source unit 3200. The electrical connection between the circuit board 3410 and the substrate 3210 may be connected by wire, for example. The wires may be disposed inside the heat discharging body 3300 to connect the circuit board 3410 and the substrate 3210.

The plurality of components 3430 include, for example, a DC converter for converting AC power supplied from an external power source to DC power, a driving chip for controlling the driving of the light source 3200, An electrostatic discharge (ESD) protection device, and the like.

The inner case 3500 houses the circuit portion 3400 therein. The inner case 3500 may have a receiving portion 3510 for receiving the circuit portion 3400. The receiving portion 3510 may have a cylindrical shape as an example. The shape of the accommodating portion 3510 may vary depending on the shape of the heat discharging body 3300. The inner case 3500 may be housed in the heat discharging body 3300. The receiving portion 3510 of the inner case 3500 may be received in a receiving portion formed on the lower surface of the heat discharging body 3300.

The inner case 3500 may be coupled to the socket 3600. The inner case 3500 may have a connection portion 3530 that engages with the socket 3600. The connection portion 3530 may have a threaded structure corresponding to the thread groove structure of the socket 3600. The inner case 3500 is nonconductive. Therefore, electrical short circuit between the circuit portion 3400 and the heat discharging body 3300 is prevented. For example, the inner case 3500 may be formed of plastic or resin.

The socket 3600 may be coupled to the inner case 3500. Specifically, the socket 3600 may be engaged with the connection portion 3530 of the inner case 3500. The socket 3600 may have the same structure as a conventional incandescent bulb. The circuit portion 3400 and the socket 3600 are electrically connected. The electrical connection between the circuit part 3400 and the socket 3600 may be connected via a wire. Accordingly, when external power is applied to the socket 3600, the external power may be transmitted to the circuit unit 3400. The socket 3600 may have a screw groove structure corresponding to the threaded structure of the connection portion 3550.

10 is an exploded perspective view 1200 of a backlight unit according to an embodiment. However, the backlight unit 1200 of FIG. 10 is an example of the illumination system and is not limited thereto.

The backlight unit 1200 according to the embodiment includes a light guide plate 1210, a light emitting module unit 1240 for providing light to the light guide plate 1210, a reflection member 1220 below the light guide plate 1210, But the present invention is not limited thereto, and may include a bottom cover 1230 for housing the light emitting module unit 1210, the light emitting module unit 1240, and the reflecting member 1220.

The light guide plate 1210 serves to diffuse light into a surface light source. The light guide plate 1210 may be made of a transparent material such as acrylic resin such as PMMA (polymethyl methacrylate), polyethylene terephthalate (PET), polycarbonate (PC), cycloolefin copolymer (COC), and polyethylene naphthalate Resin. &Lt; / RTI >

The light emitting module part 1240 provides light to at least one side of the light guide plate 1210 and ultimately acts as a light source of a display device in which the backlight unit is installed.

The light emitting module 1240 may be in contact with the light guide plate 1210, but is not limited thereto. Specifically, the light emitting module 1240 includes a substrate 1242 and a plurality of light emitting device packages 200 mounted on the substrate 1242. The substrate 1242 is mounted on the light guide plate 1210, But is not limited to.

The substrate 1242 may be a printed circuit board (PCB) including a circuit pattern (not shown). However, the substrate 1242 may include not only a general PCB, but also a metal core PCB (MCPCB), a flexible PCB (FPCB), and the like.

The plurality of light emitting device packages 200 may be mounted on the substrate 1242 such that a light emitting surface on which the light is emitted is spaced apart from the light guiding plate 1210 by a predetermined distance.

The reflective member 1220 may be formed under the light guide plate 1210. The reflection member 1220 reflects the light incident on the lower surface of the light guide plate 1210 so as to face upward, thereby improving the brightness of the backlight unit. The reflective member 1220 may be formed of, for example, PET, PC, or PVC resin, but is not limited thereto.

The bottom cover 1230 may receive the light guide plate 1210, the light emitting module 1240, and the reflective member 1220. For this purpose, the bottom cover 1230 may be formed in a box shape having an opened upper surface, but the present invention is not limited thereto.

The bottom cover 1230 may be formed of a metal material or a resin material, and may be manufactured using a process such as press molding or extrusion molding.

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,
A gallium nitride superlattice layer 124,
An undoped gallium nitride superlattice layer 124u,
Doped gallium nitride-based superlattice layer 124d,
The active layer 114, the second conductivity type semiconductor layer 116,

Claims

A first conductive semiconductor layer;
A gallium nitride superlattice layer on the first conductive type semiconductor layer;
An active layer on the gallium nitride superlattice layer; And
And a second conductive semiconductor layer on the active layer,
The gallium nitride-based superlattice layer may be formed,
An undoped gallium nitride superlattice layer on the first conductivity type semiconductor layer and a gallium nitride superlattice layer doped on the undoped gallium nitride superlattice layer.

The method according to claim 1,
The undoped gallium nitride superlattice layer
Wherein a concentration of the first conductive type element is 5 x 10 ¹⁷ (atoms / cm ³ ) or less.

The method according to claim 1,
The doped gallium nitride superlattice layer
Wherein a concentration of the first conductive type element is 1 x 10 ¹⁸ (atoms / cm ³ ) or more to 1 x 10 ¹⁹ (atoms / cm ³ ).

The method according to claim 1,
The doped gallium nitride superlattice layer
And the active layer is closer to the active layer than the undoped gallium nitride-based superlattice layer.

The method according to claim 1,
And the thickness of the doped gallium nitride superlattice layer is thinner than that of the undoped gallium nitride superlattice layer.

6. The method of claim 5,
The thickness of the doped gallium nitride superlattice layer is
And the thickness of the undoped gallium nitride superlattice layer is 10% to 30% of the thickness of the undoped gallium nitride superlattice layer.

The method according to claim 6,
The thickness of the doped gallium nitride superlattice layer is
50nm to 200nm.

The method according to claim 1,
Further comprising a current diffusion layer between the first conductivity type semiconductor layer and the gallium nitride superlattice layer,
Wherein the current diffusion layer comprises an undoped GaN layer.

9. The method of claim 8,
The current diffusion layer
And a thickness of 50 nm to 200 nm.

9. The method of claim 8,
And an electron injection layer between the current diffusion layer and the gallium nitride superlattice layer.

11. The method of claim 10,
The electron injection layer
wherein the n-type doping element is doped at a concentration of 6.0 x 10 ¹⁸ atoms / cm ³ to 8.0 x 10 ¹⁸ atoms / cm ³ .