KR102346719B1 - Light Emitting Device - Google Patents

Abstract

An embodiment relates to a light emitting device, comprising: a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; and a light extraction layer including a first insulating layer and a second insulating layer disposed on the surface of the light emitting structure.

Description

Light Emitting Device

The embodiment relates to a light emitting device, and more particularly, to a light emitting device capable of increasing light extraction efficiency by stacking insulating layers having different refractive indices.

Light emitting devices such as light emitting diodes or laser diodes using group 3-5 or group 2-6 compound semiconductor materials of semiconductors have various colors such as red, green, blue, and ultraviolet rays due to the development of thin film growth technology and device materials. By using fluorescent materials or combining colors, high-efficiency white light can be realized. Compared to conventional light sources such as fluorescent and incandescent lamps, low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness are possible. have an advantage

With the development of these technologies, light emitting diode backlight, fluorescent or incandescent light bulbs that replace Cold Cathode Fluorescence Lamp (CCFL) constituting the backlight of LCD (Liquid Crystal Display) display devices, as well as display devices as well as transmission modules of optical communication means. The application is expanding to white light emitting diode lighting devices, automobile headlights, and traffic lights that can replace them.

Here, the light emitting device is light having energy determined by an energy band unique to the material constituting the active layer (light emitting layer) when electrons injected through the first conductivity type semiconductor layer and holes injected through the second conductivity type semiconductor layer meet each other. emits

As described above, in order to improve the light extraction efficiency of light emitted from the light emitting device, a light extraction layer or the like may be additionally disposed on the light emitting device.

The 'light emitting device package' disclosed in Korean Patent Application Laid-Open No. 10-2014-0046148 includes an electrically separated first lead frame and a second lead frame; a light emitting device electrically connected to the first and second lead frames; and a molding unit surrounding the light emitting device, wherein the light emitting device includes a light extraction layer positioned on at least a portion of an upper surface in contact with the molding unit, and the light extraction layer is several micrometers to several hundred micrometers. It has a thickness in the range, and the area of the upper surface in contact with the molding part is narrower than the area of the bottom surface, and includes an inclined surface on the side. The luminous flux can be improved by minimizing total reflection.

However, since the light extraction layer is disposed only on one surface of the light emitting device, it is difficult to control the light emitted to the side of the light emitting device, and since the light extraction layer is disposed as a single layer, there is a limit in improving the light extraction efficiency.

The embodiment has been devised to solve the above problems, and it is intended to provide a light emitting device capable of improving light extraction efficiency by providing a light extraction layer in which insulating layers having different refractive indices are stacked on the surface of the light emitting device.

In order to achieve the above object, an embodiment provides a light emitting structure including a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer; and a light extraction layer including a first insulating layer and a second insulating layer disposed on the surface of the light emitting structure, wherein the refractive index of the first insulating layer and the refractive index of the second insulating layer are different from each other. do.

In an embodiment, the method further includes a first electrode pad on the first conductivity-type semiconductor layer and a second electrode pad on the second conductivity-type semiconductor layer, wherein the first electrode pad and the second electrode pad are outside the light extraction layer can be exposed as

In addition, the first insulating layer may include _{SiO 2 .}

In addition, the second insulating layer may include a spin-on-dielectric (SOD).

Here, the spin-on dielectric may include perhydropolysilazane (PHPS).

In addition, the second insulating layer may be spin coated and etched with _{NH 4 OH.}

Meanwhile, the refractive index of the second insulating layer may be smaller than that of the first insulating layer.

And, the thickness of the second insulating layer may be 1 um to 5 um.

In addition, a surface roughness may be formed on the surface of the second insulating layer.

And, it may further include a light-transmitting substrate on which the light emitting structure is disposed.

In addition, a surface roughness may be formed on the surface of the light-transmitting substrate.

According to the embodiment as described above, there is an effect that can increase the light extraction efficiency by disposing the insulating layers having different refractive indices on the surface of the light emitting device.

1 is a cross-sectional view illustrating a light emitting device according to a first embodiment.
2 is a cross-sectional view illustrating a light emitting device according to a second embodiment.
3A to 3D are views illustrating a manufacturing process of a light emitting device according to an embodiment.
4 is a graph and a table showing components constituting the second insulating layer and refractive index of the second insulating layer when the surface of the second insulating layer is _{cured with HNO 3} and NH _{4 OH, respectively.}
5A shows the surface of the second insulating layer when the surface of the second insulating layer is cured _{with H 2} O _{2 .}
5B shows the surface roughness formed on the surface of the second insulating layer when the surface of the second insulating layer is cured _{with NH 4 OH.}

Hereinafter, a preferred embodiment of the present invention that can specifically realize the above object will be described with reference to the accompanying drawings.

In the description of the embodiment according to the present invention, in the case where it is described as being formed on "on or under" of each element, on (above) or below (on) or under) includes both elements in which two elements are in direct contact with each other or one or more other elements are disposed between the two elements indirectly. In addition, when expressed as “up (up) or down (on or under)”, the meaning of not only the upward direction but also the downward direction based on one element may be included.

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 fully reflect the actual size.

1 is a cross-sectional view illustrating a light emitting device according to a first embodiment.

The light emitting device 100 according to the present embodiment may be a horizontal light emitting device, and includes a translucent substrate 120 , a light emitting structure 140 , and a light extraction layer 160 .

In the embodiment, the light-transmitting substrate 120 may be a sapphire substrate or the like, and includes, but is not limited to, a light-transmitting conductive substrate or an insulating substrate.

In addition, the light-transmitting substrate 120 may be formed of a material having excellent thermal conductivity, and in addition to sapphire (Al ₂ O ₃ ), SiO ₂ , SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, Ga ₂ 0 ₃ At least one of them can be used.

In addition, the light-emitting structure 140 in which a plurality of semiconductor compounds are stacked is disposed on one surface of the light-transmitting substrate 120 . The light emitting structure 140 includes a buffer layer 130 provided under the light-transmitting substrate 120 , a first conductivity type semiconductor layer provided under the buffer layer 130 , and including a first electrode pad 141a ( 141), an active layer 142 provided under the first conductivity type semiconductor layer 141, and a second conductivity type semiconductor layer 143 provided under the active layer 142 and including a second electrode pad 143a ) is included.

Here, the light emitting structure 140 including the first conductivity type semiconductor layer 141 , the active layer 142 , and the second conductivity type semiconductor layer 143 is formed by, for example, a metal organic chemical vapor deposition (MOCVD) method. Deposition), Chemical Vapor Deposition (CVD), Plasma-Enhanced Chemical Vapor Deposition (PECVD), Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE) ) may be formed using a method such as, but is not limited thereto.

In addition, a buffer layer 130 may be grown between the first conductivity type semiconductor layer 141 and the light-transmitting substrate 120 , in order to alleviate a lattice mismatch of materials and a difference in coefficient of thermal expansion. The material of the buffer layer 130 may be formed of a group III-5 compound semiconductor, for example, at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. An undoped semiconductor layer may be formed on the buffer layer 130 , but the present invention is not limited thereto.

In addition, the first conductivity type semiconductor layer 141 may be formed of a semiconductor compound. In more detail, it may be implemented as a compound semiconductor such as Group III-5, Group II-6, or the like, and may be doped with a first conductivity-type dopant. When the first conductivity-type semiconductor layer 141 is an n-type semiconductor layer, the first conductivity-type dopant is an n-type dopant and may include Si, Ge, Sn, Se, and Te, but is not limited thereto.

And, the first conductivity type semiconductor layer 141 is _{a semiconductor material having a composition formula of Al x} In _y Ga _(1-xy) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) may include The first conductivity type semiconductor layer 141 may be formed of any one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, and InP.

Meanwhile, in the active layer 142 , electrons injected through the first conductivity type semiconductor layer 141 and holes injected through the second conductivity type semiconductor layer 143 formed later meet each other to form the active layer 142 . A layer that emits light with an energy determined by the energy band of

In addition, the active layer 142 may have a double junction structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum wire (Quantum-Wire) structure, or a quantum dot (Quantum Dot) structure. It may be formed of at least one of the structures. For example, in the active layer 142, trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) may be injected to form a multi-quantum well structure. It is not limited.

The well layer/barrier layer of the active layer 142 may be, for example, any of InGaN/GaN, InGaN/InGaN, GaN/AlGaN, InAlGaN/GaN, InAlGaN/InAlGaN, GaAs (InGaAs)/AlGaAs, and GaP (InGaP)/AlGaP. It may be formed in one or more pair structures, but is not limited thereto. Here, the well layer may be formed of a material having a band gap lower than that of the barrier layer.

In addition, a conductive cladding layer (not shown) may be formed above and/or below the active layer 142 . The conductive cladding layer may be formed of a barrier layer of the active layer 142 or a semiconductor having a bandgap wider than the bandgap. For example, the conductive clad layer may include GaN, AlGaN, InAlGaN, or a superlattice structure. In addition, the conductivity-type cladding layer may be doped with n-type or p-type.

In addition, the second conductivity type semiconductor layer 143 may be formed of a semiconductor compound. In more detail, it may be implemented as a compound semiconductor such as Group III-5, Group II-6, or the like, and may be doped with a second conductivity-type dopant. For example, it may include a semiconductor material having a compositional formula of _{In x} Al _y Ga _{1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).} In addition, when the second conductivity-type semiconductor layer 143 is a p-type semiconductor layer, the second conductivity-type dopant is a p-type dopant and may include Mg, Zn, Ca, Sr, Ba, or the like.

On the other hand, the first electrode pad 141a provided in the light emitting device 100 is disposed on a surface in which a part of the first conductivity-type semiconductor layer 141 is mesa-etched and a part thereof is exposed, and the second electrode pad 143a is It is disposed on one side of the lower surface of the second conductivity type semiconductor layer 143 . Here, indium tin oxide (ITO) 150 may be further included between the lower surface of the second conductivity type semiconductor layer 143 and the second electrode pad 143a to increase conductivity.

In addition, the first electrode pad 141a and the second electrode pad 143a may include at least one of aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), and gold (Au). It may be formed in a single-layer or multi-layer structure, including

In addition, a light extraction layer 160 may be disposed on the surface of the light-transmitting substrate 120 and the light-emitting structure 140 to improve the external quantum efficiency of the light-emitting device 100 .

In an embodiment, the light extraction layer 160 may be disposed by stacking a first insulating layer 161 and a second insulating layer 162 having different refractive indices on the surface of the light-transmitting substrate 120 and the light emitting structure 140 . . Here, the light extraction layer 160 includes the first electrode pad 141a and the second electrode pad 143a, and the light-transmitting substrate 120 and the light-emitting structure 140 so that the lower surface of the light-transmitting substrate 120 is exposed to the outside of the light extraction layer. ) can be placed on the surface.

In addition, the refractive index of the second insulating layer 162 may be smaller than that of the first insulating layer 161. As such, the light extraction efficiency of the light emitting device is greatly improved due to the difference in refractive index between the first insulating layer and the second insulating layer. can do it

In addition, the first insulating layer 161 may include SiO ₂ , the second insulating layer 162 may include a spin-on-dielectric (SOD), and the spin-on dielectric is perhydro Polysilazane (Perhydropolysilazane: PHPS) may be included.

In addition, the thickness T1 of the first insulating layer may be arranged in a range of 1000 Å to 3000 Å. If the thickness of the first insulating layer is thinner than 1000 Å, light transmitted through the first insulating layer is not properly refracted. Also, when the thickness of the first insulating layer is greater than 3000 Å, the light transmittance of light emitted from the light emitting device may be reduced.

In addition, the thickness T2 of the second insulating layer may be arranged in a range of 1 um to 5 um. When the thickness of the second insulating layer is arranged to be thinner than 1 um, the refractive index of the light transmitted through the first insulating layer and the 2 The difference in the refractive index of light in the insulating layer is very small, so the light extraction efficiency may not be improved. .

Therefore, when the ratio of the thickness of the first insulating layer to the thickness of the second insulating layer is 0.02:1 to 0.3:1, the light extraction efficiency of the light emitting device can be improved, but the size of the light emitting device or the first insulating layer The thickness of the first insulating layer and the thickness of the second insulating layer may be determined in consideration of the refractive index of the second insulating layer.

In addition, the surface roughness 162a is formed on the second insulating layer 162 to further improve the light extraction efficiency of the light emitted from the light emitting device.

Here, the surface roughness may be formed without crystal directionality in the process of etching the second insulating layer with NH _{4 OH, and the height of the surface roughness (h R} ) may vary depending on the thickness of the second insulating layer, and on average It may be formed to be 0.05 to 0.3 times the thickness of the second insulating layer.

2 is a cross-sectional view illustrating a light emitting device according to a second embodiment.

Referring to FIG. 2 , the light emitting device 200 according to the present embodiment may be a vertical light emitting device, and includes a support substrate 210 , a bonding layer 220 , a reflective layer 230 , an ohmic layer 240 , and a light emitting structure. 250 , a channel layer 260 , a current blocking layer 270 , a second electrode 280 , and a light extraction layer 290 .

A bonding layer 220 , a reflective layer 230 , and an ohmic layer 240 are disposed on the support substrate 210 , and a light emitting structure may be disposed on the ohmic layer 240 , and A channel layer 260 may be disposed in the lower edge region.

The support substrate 210 is a base substrate and may be implemented with at least one of copper (Cu), gold (Au), nickel (Ni), molybdenum (Mo), copper-tungsten (Cu-W), and the like. Also, the support substrate 210 may be implemented as a carrier wafer, for example, Si, Ge, GaAs, ZnO, SiC, SiGe, Ga ₂ O ₃ , GaN, or the like.

A bonding layer 220 may be disposed on the support substrate 210 . The bonding layer 220 may bond the reflective layer 230 to the support substrate 210 . The bonding layer 220 may include, for example, at least one of Ti, Au, Sn, Ni, Cr, Ga, In, Bi, Cu, Ag, or Ta.

A reflective layer 230 may be formed on the bonding layer 220 . The reflective layer 230 is made of a material having excellent reflective properties, for example, silver (Ag), nickel (Ni), aluminum (Al), rubidium (Rh), palladium (Pd), iridium (Ir), ruthenium (Ru), or magnesium. (Mg), zinc (Zn), platinum (Pt), gold (Au), hafnium (Hf), and formed from a material consisting of an optional combination thereof, or the metal material and IZO, IZTO, IAZO, IGZO, IGTO, It can be formed as a multi-layer using a light-transmitting conductive material such as AZO or ATO. In addition, the reflective layer 230 may be stacked with IZO/Ni, AZO/Ag, IZO/Ag/Ni, AZO/Ag/Ni, or the like, but is not limited thereto.

An ohmic layer 240 may be formed on the reflective layer 230 . It is in ohmic contact with the lower surface of the light emitting structure 130 and may be formed in a layer or a plurality of patterns. The ohmic layer 240 may include a light-transmitting electrode layer and a metal selectively, for example, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), or indium aluminum zinc oxide (IAZO). , IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IrOx, RuOx, RuOx/ITO, Ni, Ag, Ni/IrOx/Au, and at least one of Ni/IrOx/Au/ITO may be used to form a single layer or multiple layers.

The support substrate 210 , the bonding layer 220 , the reflective layer 230 , and the ohmic layer 240 may be a first electrode and may supply a current to the light emitting structure.

A channel layer 260 may be disposed between the first electrode and the light emitting structure. The channel layer 260 may be disposed on the lower edge region of the light emitting structure and may be formed of a light-transmitting material, for example, may be formed of a metal oxide, metal nitride, light-transmitting nitride, light-transmitting oxide, or light-transmitting insulating layer. For example, the channel layer 260 may include indium tin oxide (ITO), indium zinc oxide (IZO), IZO nitride (IZON), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), or indium gallium (IGZO). zinc oxide), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), SiO2, SiOx, SiOxNy, Si3N4, Al2O3, TiO2, etc. have.

A light emitting structure 250 may be disposed on the first electrode. The light emitting structure 250 includes a first conductivity type semiconductor layer 251 , an active layer 252 , and a second conductivity type semiconductor layer 253 .

The first conductivity type semiconductor layer 251 may be implemented with a group III-V group or group II-VI compound semiconductor, and may be doped with a first conductivity type dopant. The first conductivity type semiconductor layer 251 is _{a semiconductor material having a composition formula of Al x} In _y Ga _(1-xy) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1), AlGaN , GaN, InAlGaN, AlGaAs, GaP, may be formed of any one or more of GaAs, GaAsP, AlGaInP.

When the first conductivity-type semiconductor layer 251 is an n-type semiconductor layer, the first conductivity-type dopant may include an n-type dopant such as Si, Ge, Sn, Se, Te, or the like. The first conductivity type semiconductor layer 251 may be formed as a single layer or a multilayer, but is not limited thereto.

The active layer 252 is disposed between the first conductivity type semiconductor layer 251 and the second conductivity type semiconductor layer 253 , and has a single well structure, a multiple well structure, a single quantum well structure, and a multiple quantum well. It may include any one of a (MQW: Multi Quantum Well) structure, a quantum dot structure, or a quantum wire structure.

The active layer 252 is formed of a well layer and a barrier layer, for example, AlGaN/AlGaN, InGaN/GaN, InGaN/InGaN, AlGaN/GaN, InAlGaN/GaN, GaAs (InGaAs) using a III-V group element compound semiconductor material. It may be formed in any one or more pair structure of /AlGaAs, GaP(InGaP)/AlGaP, but is not limited thereto.

The well layer may be formed of a material having an energy band gap smaller than that of the barrier layer.

The second conductivity type semiconductor layer 253 may be formed of a semiconductor compound. The second conductivity-type semiconductor layer 253 may be implemented with a group III-V group or group II-VI compound semiconductor, and may be doped with a second conductivity-type dopant. The second conductivity type semiconductor layer 253 is, for example, _{a semiconductor material having a composition formula of In x} Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1), AlGaN , GaNAlInN, AlGaAs, GaP, GaAs, GaAsP, may be formed of any one or more of AlGaInP.

When the second conductivity-type semiconductor layer 253 is a p-type semiconductor layer, the second conductivity-type dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The second conductivity type semiconductor layer 253 may be formed as a single layer or a multilayer, but is not limited thereto.

Although not shown, an electron blocking layer may be disposed between the active layer 252 and the second conductivity type semiconductor layer 253 . The electron blocking layer may have a superlattice structure. In the superlattice, for example, AlGaN doped with a second conductivity type dopant may be disposed, and GaN having a different composition ratio of aluminum is formed as a layer. A plurality may be alternately disposed with each other, but the present invention is not limited thereto.

The surface of the first conductivity-type semiconductor layer 251 can form a pattern such as irregularities to improve light extraction efficiency, and the second electrode 280 is disposed on the surface of the first conductivity-type semiconductor layer 251. As shown, the surface of the first conductivity-type semiconductor layer 251 on which the second electrode 280 is disposed may or may not form a pattern along the surface of the first conductivity-type semiconductor layer 251 . The second electrode 280 may include at least one of aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), and gold (Au) to have a single-layer or multi-layer structure. have.

A current blocking layer 270 may be disposed under the light emitting structure to correspond to the second electrode 280 . The current blocking layer 270 may be made of an insulating material, and the current blocking layer 270 may be formed of an insulating material. Accordingly, the current supplied from the direction of the support substrate 210 may be uniformly supplied to the entire region of the second conductivity-type semiconductor layer 253 .

The first insulating layer 291 is disposed so that the lower surface of the support substrate 210 and the second electrode 280 are exposed, and the second insulating layer 292 is sequentially stacked on the first insulating layer 291 to provide light An extraction layer 290 may be disposed. And, as in the first embodiment, a surface roughness 292a may be further formed on the second insulating layer 292 to further improve light extraction efficiency.

3A to 3D are views illustrating a manufacturing process of a light emitting device according to an embodiment.

As shown in FIG. 3A , a light emitting structure 140 including a buffer layer, a first conductivity type semiconductor layer 141 , an active layer 142 and a second conductivity type semiconductor layer 143 on the light transmitting substrate 120 is formed. Grow. Here, the light emitting structure is, for example, metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD; plasma-enhanced chemical vapor deposition), molecular beam growth method (MBE; Molecular Beam Epitaxy), hydride vapor phase growth method (HVPE; Hydride Vapor Phase Epitaxy) may be formed using a method such as, but is not limited thereto.

On the other hand, the light-transmitting substrate 120 may be formed of a material suitable for semiconductor material growth, a carrier wafer, and includes a light-transmitting conductive substrate or an insulating substrate, for example, sapphire (Al ₂ O ₃ ) may be used. In addition, a concave-convex structure may be formed on the light-transmitting substrate, but the present invention is not limited thereto, and impurities on the surface may be removed by wet cleaning the light-transmitting substrate.

In addition, first and second electrode pads 143a and 141a electrically connected to the substrate of the light emitting device package are disposed on the light emitting structure 140 .

In an embodiment, a light extraction layer may be disposed on the surface of the light emitting device to improve the light efficiency of light emitted from the light emitting device, and the light extraction layer may include a first insulating layer and a second insulating layer having different refractive indices, , a refractive index of the second insulating layer may be smaller than a refractive index of the first insulating layer.

As shown in FIG. 3B , the first insulating layer 161 may be disposed on the surface of the light-transmitting substrate 120 and the light emitting structure 140 so that the first and second electrode pads 143a and 141a are exposed to the outside. have. Here, when the light emitting device is mounted on the main body of the light emitting device package, since the lower surface of the transmissive substrate 120 is in contact with the lead frame of the light emitting device package, the lower surface of the light transmissive substrate 120 may also be exposed to the outside.

In addition, the thickness of the first insulating layer 161 is such that when a second insulating layer, which will be described later, is stacked on the first insulating layer 161 , the first and second electrode pads 143a and 141a are not covered. The second electrode pads 143a and 141a may be disposed to have a thickness lower than the height.

Here, the first insulating layer 161 may include SiO ₂ .

Referring to FIG. 3C , the second insulating layer 162 may be spin coated on the first insulating layer 161 so that the first and second electrode pads 143a and 141a are exposed to the outside. In addition, the refractive index of the second insulating layer 162 may be smaller than the refractive index of the first insulating layer 161 .

In addition, the second insulating layer 162 may include a spin-on-dielectric (SOD), and the spin-on dielectric may include perhydropolysilazane (PHPS).

Referring to FIG. 3D , after the second insulating layer 162 is spin-coated on the first insulating layer 161 , a surface roughness 162a is formed on the surface of the second insulating layer 162 . A thermal process is performed to form This thermal process is called a curing process. In this case, the curing process is a dry heat process performed in a furnace, and may be performed at a temperature of 200°C to 300°C.

4 is a graph and a table showing components constituting the second insulating layer and refractive index of the second insulating layer when the surface of the second insulating layer is _{cured with HNO 3} and NH _{4 OH, respectively.}

The graph of Figure 4 is a Fourier Transform Infrared Spectrum (FTIR) graph showing the light absorption of the second insulating layer. By analyzing the wavelength or intensity of the spectrum, it is possible to know the shape of molecules, the bonding force between atoms, or their composition.

After the thermal process as described above, the second insulating layer including perhydropolysilazane _{may be immersed in aqueous ammonia (NH 4} OH) to be etched. Most of the Si-H and Si-N bonds in the perhydropolysilazane are replaced with Si-O bonds through this etching process. In addition, as the second insulating layer, a silicon oxide film (SiOx) having the general formula of -(SiH2NH)n- (n is a positive integer) is formed. As shown in the graph of FIG. 5 , when the surface of the second insulating layer _{was cured with HNO 3} and when the surface of the second insulating layer was cured with NH ₄ OH, when comparing the composition of the second insulating layer, It can be confirmed that there is a Si-O bond in the second insulating layer only when it is cured with _{NH 4 OH.}

In addition, according to the embodiment, the light extraction efficiency of the light emitting device can be improved due to the difference in refractive index between the first insulating layer and the second insulating layer, when the surface of the second insulating layer _{is cured with HNO 3} and the second insulating layer The refractive indices of the second insulating layer when the surface of _{were cured with NH 4} OH were 1.443 and 1.5543, respectively, and when cured with NH ₄ OH, the refractive index of the second insulating layer was smaller.

In the embodiment, a second insulating layer having a refractive index (n2=1.443) smaller than the refractive index (n1=1.456) of the first insulating layer is laminated on the first insulating layer to emit light, and the first insulating layer and the second insulating layer It is possible to greatly improve the light extraction efficiency of the light emitting device due to the difference in the refractive index of .

FIG. 5a shows the surface of the second insulating layer when the surface of the second insulating layer _{is cured with H 2} O ₂ , and FIG. 5b is when the surface of the second insulating layer is cured _{with NH 4 OH.} 2 Indicates the surface roughness formed on the surface of the insulating layer.

Referring to FIGS. 5A and 5B , when the second insulating layer _{is cured with H 2} O ₂ , the surface of the second insulating layer is smooth, while the surface of the second insulating layer is cured _{with NH 4 OH.} It can be seen that a surface roughness is formed on the surface of the insulating layer. As such, the surface roughness formed on the surface of the second insulating layer also improves the light extraction efficiency of the light emitting device.

One or a plurality of the above-described light emitting devices may be disposed in one light emitting device package.

Here, when the light emitting device is disposed in the light emitting device package, the first electrode pad and the second electrode pad of the light emitting device may be electrically connected to the first lead frame and the second lead frame provided on the substrate of the light emitting device package, respectively. . In addition, a molding part including silicon or the like is disposed around the light emitting device to protect the light emitting device.

In addition, the above-described light emitting device or light emitting device package may be used as a light source of a lighting system, and may be used, for example, in a backlight unit of an image display device and a lighting device.

When used as a backlight unit of an image display device, it may be used as an edge-type backlight unit or a direct-type backlight unit.

In the above, the embodiment has been mainly described, but this is only an illustration and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in the range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

100, 200: light emitting element 120: light-transmitting substrate
130: buffer layer 140, 250: light emitting structure
141, 251: first conductivity type semiconductor layer 142, 252: active layer
143, 253: second conductivity type semiconductor layer 141a: first electrode pad
143a: second electrode pad 160, 290: light extraction layer
161, 291: first insulating layer 162, 292: second insulating layer

Claims (11)

a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer;
a light extraction layer including a first insulating layer and a second insulating layer disposed on the surface of the light emitting structure;
a first electrode pad on the first conductivity type semiconductor layer and a second electrode pad on the second conductivity type semiconductor layer; and
and a substrate on which the light emitting structure is disposed;
The refractive index of the first insulating layer and the refractive index of the second insulating layer are different from each other,
The first insulating layer includes SiO ₂ , and the second insulating layer includes a spin-on-dielectric (SOD),
The thickness of the second insulating layer is 1 um to 5 um, and the second insulating layer is spin coated _{and etched with NH 4} OH so that the surface of the second insulating layer has a surface roughness. roughness) is formed,
The height of the upper surfaces of the first electrode pad and the second electrode pad is higher than the height of the recessed portion of the second insulating layer in the adjacent region and lower than the height of the convex portion,
The light extraction layer is disposed on the light emitting structure and the substrate, a light emitting device. According to claim 1,
The spin-on dielectric includes perhydropolysilazane (PHPS),
The first insulating layer covers the entire side surface of the light emitting structure and the remaining upper surface of the light emitting structure except for the first and second electrode pads. delete delete 3. The method according to claim 1 or 2,
The substrate is a light-transmitting substrate,
A surface roughness is formed on the surface of the light-transmitting substrate,
The second insulating layer is disposed on the first insulating layer, a light emitting device. delete delete delete delete delete delete

Images