KR102066610B1 - Light Emitting Device - Google Patents

Abstract

The light emitting device of the embodiment is disposed on the first electrode, the first conductive type first semiconductor layer disposed on the first electrode, and the first conductive type first semiconductor layer, and is larger than the thickness of the first conductive type first semiconductor layer. A first conductivity type second semiconductor layer having a thickness, an active layer disposed on the first conductivity type second semiconductor layer and emitting light in an ultraviolet wavelength band, and a second conductivity type semiconductor layer disposed on the active layer; The first conductivity type first semiconductor layer has a smaller energy band gap than the first conductivity type second semiconductor layer.

Description

Light Emitting Device

An embodiment relates to a light emitting device.

A light emitting diode (LED) is a kind of semiconductor device that transmits and receives a signal by converting electricity into infrared light or light using characteristics of a compound semiconductor.

Group III-V nitride semiconductors are spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their physical and chemical properties.

These light emitting diodes do not contain environmentally harmful substances such as mercury (Hg) used in existing lighting equipment such as incandescent lamps and fluorescent lamps, so they have excellent eco-friendliness and have advantages such as long life and low power consumption. It is replacing them.

1 is a cross-sectional view of a conventional light emitting device, and includes a sapphire substrate 10, a light emitting structure 20, and an n-type electrode 30.

In the light emitting device of FIG. 1, the light emitting structure 20 is disposed on the sapphire substrate 10 and is composed of a p-type semiconductor layer 22, an active layer 24, and an n-type semiconductor layer 26. The p-type semiconductor layer 22 and the n-type semiconductor layer 26 are typically made of GaN. However, when light having an ultraviolet (UV) wavelength band smaller than 405 nm is emitted from the active layer 24, GaN may absorb UV light. Thus, the p-type semiconductor layer 22 and the n-type semiconductor layer 26 are emitted. ) May be made of AlGaN which absorbs light less than GaN. However, if the p-type semiconductor layer 22 is made of AlGaN, the low current characteristic may be deteriorated. That is, when a low current of several mA flows through the light emitting device, the voltage may not be greater than or equal to a threshold value, and thus the yield due to deterioration of low current characteristics may be lowered.

The embodiment provides a light emitting device in which the amount of light is reduced while the low current characteristic is improved.

The light emitting device of the embodiment includes a first electrode; A first conductivity type first semiconductor layer disposed on the first electrode; A first conductive second semiconductor layer disposed on the first conductive first semiconductor layer and having a thickness greater than that of the first conductive first semiconductor layer; An active layer disposed on the first conductive second semiconductor layer and emitting light in an ultraviolet wavelength band; And a second conductivity type semiconductor layer disposed on the active layer, wherein the first conductivity type first semiconductor layer has a smaller energy band gap than the first conductivity type second semiconductor layer. The ultraviolet wavelength band may be 330 nm to 405 nm.

The first conductivity type first semiconductor layer may include GaN, and the first conductivity type second semiconductor layer may include Al _x Ga _{1 - x} N. 0 <x <0.1, and the thickness of the first conductive type first semiconductor layer may be 5 nm or more and 10 nm or less.

The first conductivity type may be p-type, the second conductivity type may be n-type, and the light emitting device may further include an electron blocking layer disposed between the first conductivity-type second semiconductor layer and the active layer. The electron blocking layer may include AlGaN, and the concentration of aluminum included in the electron blocking layer may be greater than that of aluminum included in the first conductive type second semiconductor layer.

The first electrode may be of a first conductivity type, and the concentration of the first conductivity type dopant in the first electrode may be greater than the concentration of the first conductivity type dopant in the first conductivity type first semiconductor layer. The concentration of the first conductivity type dopant in the first conductivity type first semiconductor layer may be greater than or equal to the concentration of the first conductivity type dopant in the first conductivity type second semiconductor layer. The first conductivity type first semiconductor layer may have a first conductivity type dopant concentration of 1 × 10 E20 atoms / cm 3 to 4 × 10 E20 atoms / cm 3.

The light emitting device according to the embodiment may reduce the amount of light by reducing the thickness of the first conductive type first semiconductor layer to be less than the thickness of the first conductive type second semiconductor layer, and the first conductive type semiconductor layer is made of AlGaN. Since the first conductive semiconductor layer includes a first conductive semiconductor layer and a first conductive semiconductor layer including GaN, the electrical characteristics may be improved than when the first conductive semiconductor layer includes only AlGaN. The electrical characteristics can be improved without deteriorating the optical characteristics, such as being improved.

1 is a cross-sectional view of a conventional light emitting device.
2 is a sectional view of a light emitting device according to an embodiment.
3 is a graph showing luminous efficiency according to the thickness of the first conductivity-type first semiconductor layer.
4 shows the concentration of magnesium according to the depth from the first electrode of the light emitting device toward the first conductive type second semiconductor layer.
5A through 5I are cross-sectional views illustrating a method of manufacturing the light emitting device illustrated in FIG. 2.
6 is a cross-sectional view of a light emitting device package according to an embodiment.
7 is a cross-sectional view of a light emitting device package according to another embodiment.
8 is an exploded perspective view showing an embodiment of a lighting device including a light emitting device package according to the embodiments.
9 is an exploded perspective view illustrating an exemplary embodiment of a display device in which a light emitting device package is disposed.

Hereinafter, the present invention will be described in detail with reference to examples, and detailed description will be made with reference to the accompanying drawings in order to help understanding of the present invention. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

In the description of the embodiment according to the present invention, when described as being formed on the "top" or "bottom" (on or under) of each element, the top (bottom) or bottom (bottom) (on or under) includes both the two elements are in direct contact with each other (directly) or one or more other elements are formed indirectly between the two elements (indirectly). In addition, when expressed as "up" or "down" (on or under), it may include the meaning of the downward direction as well as the upward direction based on one element.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

2 is a sectional view of a light emitting device 100 according to an embodiment.

Referring to FIG. 2, the light emitting device 100 includes a substrate 110, a first electrode 122, a second electrode 124, a light emitting structure 130, and an electron blocking layer (EBL) 140. And a stress relaxation layer 142.

The substrate 110 may be disposed under the light emitting structure 130 and may serve as an electrode together with the first electrode 122, so that a metal having excellent electrical conductivity may be used. In addition, since the heat generated during operation of the light emitting device 100 should be sufficiently dissipated, the substrate 110 may be made of a metal having high thermal conductivity.

For example, the substrate 110 may be made of a material selected from the group consisting of molybdenum (Mo), silicon (Si), tungsten (W), copper (Cu), and aluminum (Al) or alloys thereof. In addition, the substrate 110 may include gold (Au), copper alloy (Cu Alloy), nickel (Ni), copper-tungsten (Cu-W), carrier wafers (eg, GaN, Si, Ge, GaAs, ZnO, SiGe, SiC, SiGe, Ga ₂ O _3, etc.) may be optionally included.

In addition, the substrate 110 may have a mechanical strength enough to be separated into a separate chip through a scribing process and a breaking process without causing warping of the entire nitride semiconductor.

The first electrode 122 is disposed between the substrate 110 and the light emitting structure 130. That is, the first electrode 122 is disposed under the first conductive semiconductor layer 132. The first electrode 122 may include a reflective layer (not shown) and an ohmic layer (not shown). The reflective layer is disposed between the substrate 110 and the ohmic layer, and includes silver (Ag), nickel (Ni), aluminum (Al), rhodium (Rh), palladium (Pd), iridium (Ir), ruthenium (Ru), and masne It may be formed of one layer or a plurality of layers of materials consisting of calcium (Mg), zinc (Zn), platinum (Pt), gold (Au), hafnium (Hf) and alloys of two or more thereof. For example, a reflective layer, such as aluminum (Al) or silver (Ag), may effectively reflect light emitted from the active layer 134 and traveling to the substrate 110, thereby greatly improving light extraction efficiency of the light emitting device 100. have.

In addition, the first conductivity type semiconductor layer 132 has a low impurity doping concentration and thus high contact resistance, thereby resulting in poor ohmic characteristics. The ohmic layer serves to improve these ohmic characteristics, and may be a metal, for example, silver (Ag), nickel (Ni), chromium (Cr), titanium (Ti), aluminum (Al), rhodium ( Rh), palladium (Pd), iridium (Ir), tin (Sn), indium (In), ruthenium (Ru), magnesium (Mg), zinc (Zn), platinum (Pt), gold (Au), hafnium (Hf) and a material composed of two or more of these alloys, and may be formed of one layer or a plurality of layers, but are not limited to these materials.

Alternatively, the ohmic layer may be formed of a transparent electrode, for example, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IZAZO), or IGZO (indium). gallium zinc oxide (IGTO), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IZO Nitride (IZON), AZO (Al-Ga ZnO), IGZO (IGZO) In—Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au, and Ni / IrOx / Au / ITO, and may be formed, but are not limited to these materials.

Alternatively, the first electrode 122 may be formed of one layer or a plurality of layers which perform both the function of the reflective layer and the function of the ohmic layer, but is not limited thereto. When the substrate 110 serves as the first electrode 122, the first electrode 122 may be omitted.

In addition, according to an embodiment, the first electrode 122 or the ohmic layer of the first electrode 122 may be implemented with a first conductivity type semiconductor compound. For example, the first electrode 122 may be implemented with p-type GaN.

Although not shown, a bonding layer may be further disposed between the substrate 110 and the first electrode 122. The bonding layer corresponds to an adhesion layer coupling the first electrode 122 and the substrate 110. However, when the first electrode 122 performs the function of the bonding layer, the bonding layer may be omitted as illustrated in FIG. 2. For example, the bonding layer is composed of gold (Au), tin (Sn), indium (In), aluminum (Al), silicon (Si), silver (Ag), nickel (Ni), and copper (Cu). It may be formed of a material selected from or alloys thereof.

The light emitting structure 130 includes a first conductive semiconductor layer 132, an active layer 134, and a second conductive semiconductor layer 136 sequentially disposed on the substrate 110. The first conductive semiconductor layer 132 is disposed between the first electrode 122 and the active layer 134, and the active layer 134 is the first conductive semiconductor layer 132 and the second conductive semiconductor layer. The second conductive semiconductor layer 136 is disposed over the active layer 134.

The first conductivity type semiconductor layer 132 may be formed of a compound semiconductor. The first conductive semiconductor layer 132 may be formed of a compound semiconductor such as a group III-IV group or a group II-V group, and may be doped with the first conductive dopant. When the first conductive semiconductor layer 132 is a p-type semiconductor layer, the first conductive dopant is a p-type dopant, and includes magnesium (Mg), zinc (Zn), calcium (Ca), strontium (Sr), Barium (Ba) and the like.

In example embodiments, the first conductivity-type semiconductor layer 132 includes a first conductivity-type first semiconductor layer 132A and a first conductivity-type second semiconductor layer 132B.

The first conductive first semiconductor layer 132A is disposed on the first electrode 122, and the first conductive second semiconductor layer 132B is disposed on the first conductive first semiconductor layer 132A. When the active layer 134 emits light in the ultraviolet (UV: UltraViolet) wavelength band, the first conductivity type first semiconductor layer 132A may have _a composition formula of In _a Ga _(1-a) N (0 ≦ a <1). It may include a semiconductor material having a. The first conductivity-type second semiconductor layer 132B may be made of, for example, a semiconductor material including Al _x Ga _{1- x} N (0 <x <0.1).

In addition, an energy band gap of the first conductive first semiconductor layer 132A may be smaller than that of the first conductive second semiconductor layer 132B.

The active layer 134 is disposed on the first conductivity-type second semiconductor layer 132B, and the holes (or electrons) and the second conductivity-type semiconductor layer 136 injected through the first conductivity-type semiconductor layer 132 are provided. Electrons (or holes) injected through each other meet each other and emit light having energy determined by an energy band inherent in the material forming the active layer 134. In particular, the active layer 134 may emit light in the ultraviolet (UV) wavelength band. For example, light in the near ultraviolet (NUV: Near UV) wavelength band of the 330 nm to 405 nm wavelength band may be emitted.

The active layer 134 may include a single well structure, a multi well structure, a single quantum well structure, a multi quantum well structure (MQW), a quantum-wire structure, or a quantum dot. ) And at least one of the structures.

The active layer 134 may have a structure in which a plurality of well layers and barrier layers are alternately stacked. The well layer / barrier layer of the active layer 134 may be formed of any one or more pair structures of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP. However, the present invention is not limited thereto. In particular, when the active layer 134 emits light in the ultraviolet wavelength band, the barrier layer may include aluminum (Al), and the well layer may include indium (In). In this case, the barrier layer may be made of AlGaN, and the well layer may be made of InGaN. The well layer may be formed of a material having a band gap energy less than the band gap energy of the barrier layer.

A conductive clad layer (not shown) may be disposed between the active layer 134 and the second conductive semiconductor layer 136. The conductive clad layer may be formed of a semiconductor having a band gap energy wider than the band gap energy of the barrier layer of the active layer 134. For example, the conductive cladding layer may include GaN, AlGaN, InAlGaN, or a super lattice (SL) structure. In addition, the conductive clad layer may be doped with n-type or p-type. In some cases, the conductive cladding layer may be omitted.

The second conductivity type semiconductor layer 136 may be formed of a semiconductor compound. The second conductive semiconductor layer 136 may be implemented with compound semiconductors such as III-V and II-VI, and may be doped with the second conductive dopant. For example, the second conductivity-type semiconductor layer 136 has a composition formula of Al _x In _y Ga _(1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). The semiconductor material may include at least one of InAlGaN, AlGaAs, and AlGaInP. When light in the ultraviolet wavelength band is emitted from the active layer 134, the second conductivity-type semiconductor layer 136 may be implemented with AlGaN which absorbs light less than GaN. If the second conductivity-type semiconductor layer 136 is an n-type semiconductor layer, the second conductivity-type dopant is an n-type dopant and may include Si, Ge, Sn, Se, Te, but is not limited thereto.

The first conductive semiconductor layer 132 may be a p-type semiconductor layer, and the second conductive semiconductor layer 136 may be an n-type semiconductor layer. Alternatively, the first conductive semiconductor layer 132 may be an n-type semiconductor layer, and the second conductive semiconductor layer 136 may be a p-type semiconductor layer. The light emitting structure 130 may be implemented as 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.

Hereinafter, for convenience, the first conductive semiconductor layer 132 will be described as a p-type semiconductor layer and the second conductive semiconductor layer 136 will be described as an n-type semiconductor layer, but embodiments are not limited thereto.

The light emitting device 100 illustrated in FIG. 2 may further include an electron blocking layer 140 disposed between the active layer 134 and the p-type second semiconductor layer 132B. Since the electron blocking layer 140 has a larger band gap energy than the p-type semiconductor layer 132, electrons provided from the n-type semiconductor layer 136 to the active layer 134 are recombined in the active layer 134 of the MQW structure. Can be effectively prevented from overflowing to the p-type semiconductor layer 132. Accordingly, the electron blocking layer 140 may improve light efficiency of the light emitting device 100 by reducing electrons consumed due to overflowing. In order to obtain an electron blocking effect, the electron blocking layer 140 should have a large band gap energy and an optimal thickness. As the electron blocking layer 140, a p-type AlGaN or a p-type InAlGaN layer may be mainly used.

In addition, a stress relaxation layer 142 may be further disposed between the second conductivity-type semiconductor layer 136 and the active layer 134. The stress relaxation layer 142 is intended to mitigate lattice mismatch between the second conductivity-type semiconductor layer 136 and the active layer 134. The stress relaxation layer 142 may have a superlattice structure in which a plurality of well layers and a barrier layer are alternately stacked. The well layer / barrier layer of the stress relaxation layer 142 is at least one of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, InGaN / AlGaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP It may be formed in a pair structure, but is not limited thereto. The well layer of the stress relaxation layer 142 may be formed of a material having a larger energy band gap than the well layer of the active layer 134.

The second electrode 124 may be disposed on the second conductivity type semiconductor layer 136. The second electrode 124 may be formed of a metal, and may also be formed of a reflective electrode material having ohmic characteristics. For example, the second electrode 124 includes at least one of aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), and gold (Au). It can be formed as.

Although not shown, the upper portion of the second conductivity-type semiconductor layer 136 may have a photonic crystal structure or roughness to increase light extraction efficiency.

Hereinafter, the features of the first conductive semiconductor layer 132 illustrated in FIG. 2 will be described in more detail.

In example embodiments, the thickness T2 of the first conductivity-type second semiconductor layer 132B may be greater than the thickness T1 of the first conductivity-type first semiconductor layer 132A.

3 is a graph showing luminous efficiency according to the thickness T1 of the first conductive type first semiconductor layer 132A, where the horizontal axis represents the thickness T1 and the vertical axis represents the light amount Po.

In FIG. 3, the light quantity of the light emitting device 100 is measured by an optical quick check (OQC) device, which is a type of EL (Electro Luminescenece), in the wafer stage.

The graph result of FIG. 3 is an example of the case where the first conductivity type first semiconductor layer 132A is InGaN or GaN, and the active layer 134 when the thickness T1 of the first conductivity type first semiconductor layer 132A is large. Light emitted from the UV wavelength band may be absorbed by the first conductivity type first semiconductor layer 132A, and thus the amount of light may be reduced. Alternatively, when the thickness T1 of the first conductive type first semiconductor layer 132A is less than 50 kW, the amount of light may decrease. Accordingly, the thickness T1 of the first conductive type first semiconductor layer 132A may be 5 nm or more and 10 nm or less, that is, 50 mW or more and 100 mW or less. When the first conductivity type first semiconductor layer 132A has the thickness T1, it can be seen that the luminous efficiency Po of the light emitting device 100 is maximized. The thickness T1 of the first conductive type first semiconductor layer 132A, which maximizes luminous efficiency, may be, for example, 10 nm (ie, 100 μs).

According to an embodiment, when the first concentration of the first conductive dopant is doped into the second conductive semiconductor layer 132B, the first conductive dopant is deposited into the first conductive doped semiconductor layer 132A. The doped second concentration is greater than the first concentration. In addition, the third concentration of the first electrode 122 doped with the first conductivity type dopant is greater than the second concentration. Therefore, the hole concentration may decrease from the first electrode 122 to the electron blocking layer 140. Specifically, it is as follows.

4 shows the concentration of magnesium (Mg) according to the depth from the first electrode 122 of the light emitting device 100 to the first conductive type second semiconductor layer 132B, and the vertical axis represents the concentration of Mg, The horizontal axis represents the depth of the light emitting element 100, respectively.

The first conductivity type dopant uses Mg as the p type dopant, the first conductivity type semiconductor layer 132 is a p type semiconductor layer, the second conductivity type semiconductor layer 136 is an n type semiconductor layer, and the electron blocking layer When 140 is implemented with p-type AlGaN and the first electrode 122 is implemented with p-type GaN, the concentration of Mg according to the depth of the light emitting device 100 is as shown in FIG. 4.

Referring to FIG. 4, the doping concentration of Mg may gradually decrease from the p-type first electrode 122 to the chariot blocking layer 140. That is, the concentration of Mg in the p-type first electrode 122 may be greater than the concentration of Mg in the first conductive type first semiconductor layer 132A. In addition, the concentration of Mg in the p-type first semiconductor layer 132A may be greater than or equal to the concentration of Mg in the p-type second semiconductor layer 132B. For example, the p-type first semiconductor layer 132A may have an Mg concentration of 1 × 10E20 atoms / cm 3 to 4 × 10E20 atoms / cm 3.

Meanwhile, the aluminum concentration of the p-type electron blocking layer 140 may be greater than the aluminum concentration of the p-type second semiconductor layer 132B.

Typically, when the active layer 134 emits light in the ultraviolet wavelength band, the first conductivity-type semiconductor layer 132 is made of AlGaN instead of GaN. That is, in the conventional case, the first conductive semiconductor layer 132 includes only the first conductive second semiconductor layer 132B. However, according to the present embodiment, the first conductive semiconductor layer 132 is not only the first conductive second semiconductor layer 132B made of AlGaN, but also In _a Ga _(1-a) N (0 ≦ a <1). Since the first conductive type first semiconductor layer 132A is further included, the low current yield may be improved when the light emitting device 100 is manufactured.

Hereinafter, the low current yield of the light emitting device 100 according to the embodiment will be described as follows.

First, the conventional p-type semiconductor layer 22 of FIG. 1 is implemented by AlGaN, and the first conductive type first semiconductor layer 132A of FIG. 2 of the present embodiment is implemented by p-type GaN, and the first conductivity type agent 2 semiconductor layer 132B is made of p-type AlGaN, the first conductivity type dopant is made of Mg as p-type dopant, and the first conductivity type second semiconductor layer 132B is doped with Mg, which is p-type dopant. Is changed from 220 sccm (Standard Cubic Centimeter per Minute) to 340 sccm, the stress relaxation layer 142 is implemented in the InGaN / GaN superlattice structure, the second conductivity-type semiconductor layer 136 is implemented in n-type AlGaN The first electrode 122 is implemented with p-type GaN.

Thereafter, a low current of 1 kV to 10 kV was allowed to flow through the light emitting device 100, and then it was measured whether the voltage of the light emitting device 100 was greater than or equal to a threshold value. At this time, the yield of the conventional light emitting device and the light emitting device 100 of the embodiment is shown in Table 1.

Lot number yield(%) Magnesium concentration (sccm) p-type semiconductor layer One Of FIG. 2
Light emitting element 87.7 340 AlGaN / GaN 2 70.8 to 77.9 220 3 64.4 275 4 71.8 308 5 79.8 or 86.3 264 6 Of FIG. 1
Light emitting element 26.6 . AlGaN 7 47.8 8 0 9 24.8 10 42.7 11 51.6 12 12.8

Referring to Table 1, in the present embodiment in which the first conductivity-type semiconductor layer 132 is composed of a p-type GaN layer 132A and a p-type AlGaN layer 132B, the p-type semiconductor layer 22 is a p-type AlGaN layer. It can be seen that the yield is much improved due to the improved low current characteristics compared to the existing one.

As described above, in order to prevent the light quantity decrease when the light emitting device 100 according to the embodiment improves the low current characteristic, the thickness T1 of the first conductive type first semiconductor layer 132A is changed to the first conductive type. It may be smaller than the thickness T2 of the second semiconductor layer 132B. Therefore, the light emitting device 100 of the embodiment can improve the electrical characteristics without degrading the optical characteristics.

Hereinafter, a manufacturing method according to an embodiment of the above-described light emitting device 100 will be described. However, the light emitting device 100 illustrated in FIG. 2 is not limited thereto and may be manufactured by other methods.

5A through 5I are cross-sectional views illustrating a method of manufacturing the light emitting device 100 shown in FIG. 2.

As shown in FIG. 5A, a buffer layer 160 is formed on the substrate 150. Here, the substrate 150 includes a conductive substrate or an insulating substrate, for example, at least one of sapphire (Al ₂ O ₃ ), SiC, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga ₂ 0 ₃ . Can be used. As a method of forming the substrate 150 into a conductive type, an electrochemical metal deposition method or a bonding method using a eutectic metal may be used.

The buffer layer 160 is intended to mitigate lattice mismatch between the substrate 150 and the light emitting structure 130. The material of the buffer layer 160 may be formed of at least one of a group III-V compound semiconductor, for example, GaN, InN, AlN, InGaN, AlGaN, InAlGaN, or AlInN. The buffer layer 160 itself may include an undoped nitride or an undoped semiconductor layer may be formed on the buffer layer 160, but is not limited thereto. The buffer layer 160 may be omitted depending on the type of the substrate 150 and the type of the light emitting structure 130.

Thereafter, as shown in FIG. 5B, the second conductivity-type semiconductor layer 136 is formed on the buffer layer 160. The second conductive semiconductor layer 136 may be formed of, for example, a metal organic chemical vapor deposition (MOCVD), a chemical vapor deposition (CVD), or a plasma-enhanced chemical vapor deposition (PECVD). ), Molecular beam growth (MBE: Molecular Beam Epitaxy), hydride vapor phase growth (HVPE: Hydride Vapor Phase Epitaxy) can be formed using a method such as, but is not limited thereto.

Subsequently, referring to FIG. 5C, a stress relaxation layer 142 is formed on the second conductive semiconductor layer 136. The stress relaxation layer 142 may have a superlattice structure in which a plurality of well layers and a barrier layer are alternately stacked. The well layer / barrier layer of the stress relaxation layer 142 is at least one of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, InGaN / AlGaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP It may be formed in a pair structure, but is not limited thereto. The well layer of the stress relaxation layer 142 may be formed of a material having a larger energy band gap than the well layer of the active layer 134.

Thereafter, referring to FIG. 5D, an active layer 134 is formed on the stress relaxation layer 142. The active layer 134 is injected with, for example, aluminum, trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) to form the active layer 134 in a multi-quantum well structure. This may be formed but is not limited thereto.

Subsequently, referring to FIG. 5E, the electron blocking layer 140 and the first conductivity type second semiconductor layer 132B are formed on the active layer 134. The composition of the electron blocking layer 140 and the composition of the first conductivity-type second semiconductor layer 132B are the same as described above. Bicetyl cyclopentadienyl containing, for example, p-type impurities such as aluminum (Al), trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and magnesium (Mg) Mg (C ₂ H ₅ C ₅ H ₄ ) ₂ } may be implanted with magnesium (EtCp ₂ Mg) to form a p-type AlGaN layer, but is not limited thereto. In this case, the first conductive dopant 131 is doped to a first concentration to form the first conductive second semiconductor layer 132B.

5F, a first conductive first semiconductor layer 132A is formed on the first conductive second semiconductor layer 132B. The composition of the first conductivity-type first semiconductor layer 132A is as described above. For example, bicetyl cyclopentadienyl magnesium (EtCp ₂ Mg) containing p-type impurities such as trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and magnesium (Mg) in the chamber. ) {Mg (C ₂ H ₅ C ₅ H ₄ ) ₂ } may be implanted to form a p-type GaN layer, but is not limited thereto. In this case, the first conductivity type dopant 133 is doped to a second concentration greater than the first concentration to form the first conductivity type first semiconductor layer 132A.

Subsequently, referring to FIG. 5G, the first electrode 122 may be formed on the first conductive semiconductor layer 132 by sputtering or electron beam deposition. At this time, the first conductive dopant 135 is doped to a third concentration greater than the second concentration to form the first electrode 122.

Subsequently, referring to FIG. 5H, the substrate 110 may be formed on the first electrode 122. The substrate 110 may be formed using an electrochemical metal deposition method or a bonding method using an etchant metal.

Thereafter, as shown in FIG. 5I, the substrate 150 and the buffer layer 160 are separated from the second conductive semiconductor layer 136. The substrate 150 may be removed by a laser lift off (LLO) method using an excimer laser or the like, or may be performed by a dry or wet etching method.

For example, when the laser lift-off method focuses and irradiates excimer laser light having a predetermined wavelength in the direction of the substrate 150, heat is formed on the interface between the substrate 150 and the second conductivity-type semiconductor layer 136. As the energy is concentrated and the interface is separated into gallium and nitrogen molecules, the substrate 150 is instantaneously separated from the portion where the laser light passes, and the buffer layer 160 may be separated together.

Thereafter, as shown in FIG. 5I, after the substrate 150 and the buffer layer 160 have been removed, the resultant is inverted. Then, as illustrated in FIG. 2, the second electrode 124 is formed on the second conductive semiconductor layer 136. do.

Hereinafter, the configuration and operation of the light emitting device package including the light emitting device will be described.

6 is a cross-sectional view of a light emitting device package 200 according to an embodiment.

The light emitting device package 200 according to the embodiment is disposed on the package body 205, the first and second lead frames 213 and 214 installed on the package body 205, and the package body 205. The light emitting device 220 may be electrically connected to the first and second lead frames 213 and 214, and the molding member 240 may surround the light emitting device 220.

The package body 205 may be formed of silicon, synthetic resin, or metal, and an inclined surface may be formed around the light emitting device 220.

The first and second lead frames 213 and 214 are electrically separated from each other, and serve to supply power to the light emitting device 220. In addition, the first and second lead frames 213 and 214 may serve to increase light efficiency by reflecting light generated from the light emitting device 220, and transmit heat generated from the light emitting device 220 to the outside. It can also play a role.

The light emitting device 220 may be the light emitting device 100 illustrated in FIG. 2, but is not limited thereto.

The light emitting device 220 may be disposed on the second lead frame 214 as illustrated in FIG. 6, but may be disposed on the first lead frame 213 or the package body 205.

The light emitting device 220 may be electrically connected to the first and / or second lead frames 213 and 214 by any one of a wire method and a die bonding method. The light emitting device 220 illustrated in FIG. 6 may be electrically connected to the first lead frame 213 and the wire 230 and may be directly electrically connected to the second lead frame 214, but is not limited thereto.

The molding member 240 may surround and protect the light emitting device 220. In addition, the molding member 240 may include a phosphor to change the wavelength of light emitted from the light emitting device 220.

7 is a cross-sectional view of a light emitting device package 300 according to another embodiment.

The light emitting device package 300 according to another exemplary embodiment includes a body 310, a heat dissipation block 360 disposed in the body 310, and a light emitting element 100 disposed on the heat dissipation block 360. Here, the light emitting device 100 may be the light emitting device 100 illustrated in FIG. 2.

The body 310 may be implemented with a plurality of layers 311, 312, 313, and 314. The number of layers constituting the body 310 may vary depending on the embodiment.

When the light emitting device 100 is a UV LED emitting ultraviolet light, the body 310 may be made of a material that is not deteriorated by ultraviolet light, for example, may be made of a ceramic material. As an example, the body 310 may be implemented by a low temperature co-fired ceramic (LTCC) method. In addition, the body 310 may be implemented by a high temperature co-fired ceramic (HTCC) method. In addition, the body 310 may include Si0 ₂ , Si _x O _y , Si ₃ N ₄ , Si _x N _y , SiO _x N _y , Al ₂ O ₃ , or AlN.

The body 310 may supply a current to the light emitting device 100 through a via hole formed through each of the layers 311 to 314 and a conductive pattern positioned between the layers 311 to 314.

The heat dissipation block 360 is disposed in the body 310. The heat dissipation block 360 effectively transfers heat generated from the light emitting device 100 to the outside. The heat dissipation block 360 may be formed of Cu or an alloy including Cu, but is not limited thereto.

A plurality of light emitting device packages according to the embodiment may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, and the like, which are optical members, may be disposed on an optical path of the light emitting device package. The light emitting device package, the substrate, and the optical member may function as a light unit. Another embodiment may be implemented as a display device, an indicator device, or a lighting system including the semiconductor light emitting device or the light emitting device package described in the above embodiments, and for example, the lighting system may include a lamp or a street lamp. .

8 is an exploded perspective view showing an embodiment of a lighting device including a light emitting device package according to the embodiments.

The lighting apparatus according to the embodiment includes a light emitting module 600 for projecting light, a housing 400 in which the light emitting module 600 is built, and a heat dissipation part 500 and a light emitting module 600 for dissipating heat from the light emitting module 600. And a holder 700 for coupling the heat dissipation part 500 to the housing 400.

The housing 400 includes a socket coupling portion 410 coupled to an electrical socket (not shown), and a body portion 420 connected to the socket coupling portion 410 and having a light source 600 built therein. One air flow port 430 may be formed in the body portion 420.

A plurality of air flow port 430 is provided on the body portion 420 of the housing 400, the air flow port 430 is composed of one air flow port, or a plurality of flow ports other than the radial arrangement as shown Various arrangements are also possible.

The light emitting module 600 includes a plurality of light emitting device packages 650 disposed on the circuit board 610. The light emitting device package 650 may include the light emitting device packages 200 and 300 of FIG. 6 or 7. The circuit board 610 may have a shape that may be inserted into an opening of the housing 400, and may be made of a material having high thermal conductivity to transfer heat to the heat dissipation part 500, as described below.

A holder 700 is provided below the light emitting module, and the holder 700 may include a frame and another air flow port. In addition, although not shown, an optical member may be provided below the light emitting module 600 to diffuse, scatter, or converge the light projected from the light emitting device module 650 of the light emitting module 600.

9 is an exploded perspective view illustrating an exemplary embodiment of a display device 800 in which a light emitting device package is disposed.

Referring to FIG. 9, the display device 800 according to the embodiment is disposed in front of the light emitting modules 830 and 835, the reflector 820 on the bottom cover 810, and the reflector 820, and emits light from the light emitting module. The light guide plate 840 for guiding the light to the front of the display device, the first prism sheet 850 and the second prism sheet 860 disposed in front of the light guide plate 840, and the front of the second prism sheet 860. It comprises a panel 870 disposed in the color filter 880 disposed in the first half of the panel 870.

The light emitting module includes the above-described light emitting device package 835 on the circuit board 830. Here, the circuit board 830 may be a PCB or the like, and the light emitting device package 835 may be, for example, the light emitting device packages 200 and 300 illustrated in FIG. 6 or 7.

The bottom cover 810 may receive components in the display device 800. The reflecting plate 820 may be provided as a separate component as shown in the figure, or may be provided in the form of coating with a highly reflective material on the back of the light guide plate 840, or the front of the bottom cover 810.

Here, the reflective plate 820 may use a material having a high reflectance and being extremely thin, and may use polyethylene terephthalate (PET).

The light guide plate 840 scatters the light emitted from the light emitting device package module so that the light is uniformly distributed over the entire area of the screen of the liquid crystal display. Accordingly, the light guide plate 840 is made of a material having a good refractive index and a high transmittance, and may be formed of polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), or the like. In addition, the light guide plate may be omitted, and thus an air guide method in which light is transmitted in a space on the reflective sheet 820 may be possible.

The first prism sheet 850 is formed of a translucent and elastic polymer material on one surface of the support film, and the polymer may have a prism layer in which a plurality of three-dimensional structures are repeatedly formed. Here, the plurality of patterns may be provided with a stripe and a valley repeatedly as shown in the stripe type.

In the second prism sheet 860, the direction of the floor and the valley of one surface of the support film may be perpendicular to the direction of the floor and the valley of one surface of the support film in the first prism sheet 850. This is to evenly distribute the light transmitted from the light emitting module and the reflective sheet in the front direction of the panel 870.

In this embodiment, the first prism sheet 850 and the second prism sheet 860 form an optical sheet, which may be formed of another combination, for example, a micro lens array or a combination of a diffusion sheet and a micro lens array. It may be made of a combination of one prism sheet and a micro lens array.

The liquid crystal display panel (Liquid Crystal Display) may be disposed on the panel 870, and other types of display devices requiring a light source may be provided in addition to the liquid crystal display panel.

The panel 870 is in a state where the liquid crystal is located between the glass bodies and the polarizing plates are placed on both glass bodies in order to use the polarization of light. Here, the liquid crystal has an intermediate characteristic between a liquid and a solid. The liquid crystal, which is an organic molecule having a fluidity like a liquid, has a state in which the liquid crystal is regularly arranged like a crystal, and the image of the liquid crystal is changed by an external electric field. Is displayed.

The liquid crystal display panel used in the display device uses a transistor as an active matrix method as a switch for adjusting a voltage supplied to each pixel.

The front surface of the panel 870 is provided with a color filter 880 to transmit the light projected by the panel 870, only the red, green and blue light for each pixel can represent an image.

Although described above with reference to the embodiments are only examples and are not intended to limit the present invention, those skilled in the art to which the present invention pertains are not exemplified above within the scope not departing from the essential characteristics of the present embodiment. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will be construed as being included in the scope of the invention defined in the appended claims.

100, 220: light emitting element 110: substrate
122: first electrode 124: second electrode
130: light emitting structure 132: first conductive semiconductor layer
132A: first conductivity type first semiconductor layer 132B: first conductivity type second semiconductor layer
134: active layer 136: second conductive semiconductor layer
140: electron blocking layer 142: stress relaxation layer
200 and 300: light emitting device package 205: package body
213, 214: lead frame 230: wire
240: molding member 310: body
360: heat dissipation block 311, 312, 313, 314: a plurality of layers
400: housing 500: heat dissipation unit
600: light emitting module 700: holder
800: display device 810: bottom cover
820: reflectors 830, 835: light emitting module
840: Light guide plate 850, 860: Prism sheet
870: panel 880: color filter

Claims (10)

A first electrode doped to a first concentration by a first conductivity type dopant;
A first conductivity type first semiconductor layer disposed on the first electrode and doped to a second concentration by the first conductivity type dopant;
A first conductive type second disposed on the first conductive type first semiconductor layer and having a thickness greater than that of the first conductive type first semiconductor layer and doped to a third concentration by the first conductive type dopant A semiconductor layer;
An active layer disposed on the first conductive second semiconductor layer and emitting light in an ultraviolet wavelength band; And
A second conductivity type semiconductor layer disposed on the active layer,
The first conductive type first semiconductor layer has a smaller energy band gap than the first conductive type second semiconductor layer,
Wherein the first concentration is greater than the second concentration and the second concentration is greater than the third concentration. The light emitting device of claim 1, wherein the first conductivity type first semiconductor layer comprises GaN, and the first conductivity type second semiconductor layer includes Al _x Ga _{1 - x} N. The light emitting device according to claim 2, wherein 0 <x <0.1. The light emitting device of claim 2, wherein the first conductive semiconductor layer has a thickness of 5 nm or more and 10 nm or less. The electron blocking layer of claim 1 or 2, wherein the first conductivity type is p-type, the second conductivity type is n-type, and an electron blocking layer disposed between the first conductivity type second semiconductor layer and the active layer. A light emitting device further comprising. The light emitting device of claim 5, wherein the electron blocking layer comprises AlGaN, and the concentration of aluminum included in the electron blocking layer is greater than that of aluminum included in the first conductive type second semiconductor layer. delete delete The light emitting device of claim 1, wherein the first conductivity type first semiconductor layer has a first conductivity type dopant concentration of 1 × 10E20 atoms / cm 3 to 4 × 10E20 atoms / cm 3. The light emitting device of claim 1, wherein the ultraviolet wavelength band is 330 nm to 405 nm.

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