KR20200018996A - Light emitting diode having light scattering pattern - Google Patents

Abstract

Provided is a light emitting diode having a light scattering pattern. According to an embodiment of the present invention, the light emitting diode comprises: a substrate; a semiconductor stacked structure arranged on the substrate and including a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer; and a pattern of light scattering elements arranged between the substrate and the semiconductor stacked structure. The light scattering element includes dielectric layers having different refractive indexes from each other and has a hemisphere shape, a shell shape, or a cone shape.

Description

Light-emitting diodes having a light scattering pattern {LIGHT EMITTING DIODE HAVING LIGHT SCATTERING PATTERN}

The present invention relates to light emitting diodes, and more particularly to light emitting diodes having a light scattering pattern.

Light emitting diodes are used in a variety of products such as large back light units (BLUs), general lighting and electrical equipment, and are also widely used in small home appliances and interior products.

Meanwhile, various studies have been conducted to increase the external quantum efficiency of light emitting diodes to provide high efficiency light emitting diodes. In particular, the patterned sapphire substrate has been applied to increase the light extraction efficiency.

The problem to be solved by the present invention is to provide a light emitting diode having a high light extraction efficiency.

Another object of the present invention is to provide a light emitting diode capable of increasing the amount of light emitted in the direction of the upper surface of the substrate as compared to the substrate side direction.

A light emitting diode according to an embodiment of the present invention, a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; A pattern of light scattering elements disposed between the substrate and the semiconductor stack, the light scattering elements comprising dielectric layers having different refractive indices and having a hemispherical shape, shell shape, or cone shape.

In another embodiment, a light emitting diode includes: a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; A pattern of light scattering elements disposed between the substrate and the semiconductor stack, the light scattering elements including dielectric layers having different refractive indices, the light scattering elements having a bottom surface in contact with the substrate, and upwardly from the bottom surface. Increasingly narrower, the top of the light scattering element is curved or cusp.

In another embodiment, a light emitting diode includes: a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; A pattern of light scattering elements disposed between the substrate and the semiconductor stack, wherein the light scattering elements comprise dielectric layers having different refractive indices, the light scattering elements contacting the substrate and the top facing the bottom surface. It includes, the width becomes narrower toward the top end from the lower surface, the width of the upper end is less than 1/10 of the width of the lower surface.

According to embodiments of the present invention, light extraction efficiency may be improved by adopting light scattering elements including dielectric layers having different refractive indices between the substrate and the semiconductor stack. Furthermore, the amount of light emitted to the upper surface of the substrate may be increased compared to the light emitted to the side of the substrate.

Other features and advantages of the invention will be apparent from the following detailed description.

1 is a schematic cross-sectional view for describing a light emitting diode according to an embodiment of the present invention.
2 is an enlarged cross-sectional view of a portion of FIG. 1 to explain a light scattering element.
3 is a schematic perspective view for explaining various shapes of the light scattering elements.
FIG. 4 is a simulation graph for explaining reflectance and reflection band according to deposition conditions of dielectric layers for forming a light scattering element.
5 is a graph illustrating a pointing vector value according to the prior art and various embodiments of the present disclosure.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention pertains. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. In addition, when one component is described as "on" or "on" another component, each component is different from each other as well as when the component is "right on" or "on" another portion. It also includes a case where another component is interposed therebetween. Like numbers refer to like elements throughout the specification.

A light emitting diode according to an embodiment of the present invention, a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; A pattern of light scattering elements disposed between the substrate and the semiconductor stack, the light scattering elements comprising dielectric layers having different refractive indices and having a hemispherical shape, shell shape, or cone shape.

By forming light scattering elements using dielectric layers having different refractive indices, the light scattering effect may be increased to improve light extraction efficiency. Moreover, these light scattering elements increase the amount of light emitted to the top side of the substrate relative to the light emitted to the side of the substrate.

In this embodiment, the hemispherical shape or shell shape does not only mean that the top is perfectly curved, but includes the intentional or process limitations that the flat surface remains at the top. In addition, the cone shape does not only mean that the top is perfectly pointed, but intentionally includes the flat surface remaining at the top as a process limit. However, the flat surface formed at the top is extremely limited, for example, 1/10 or less of the width of the bottom surface (bottom surface) of the light scattering element. Therefore, even when an extremely small flat surface of 1/10 or less than the lower surface is formed at the top, it can be included in the hemispherical shape, shell shape or cone shape.

Further, the cone shape of the light scattering element may include a cone shape, a triangular pyramid shape, a convex conical shape at the bottom, a shield shape at the bottom and a convex triangular pyramid shape, a ballistic conical shape, or a ballistic conical shape with the lower side convex. .

Meanwhile, the bandwidth of the reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices may be 40 nm or more, and the peak wavelength of the light emitted from the active layer may be located within the bandwidth. have.

Further, the peak wavelength of the light may be located within ± 10% of the bandwidth from the center of the bandwidth region.

In addition, the bandwidth of the reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as those of the dielectric layers having different refractive indices may be 70 nm or more, and more than 90 nm.

Meanwhile, the maximum reflectance of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices may be in a range of 20% to 90%. Within this range, light extraction efficiency of the light emitting diode can be improved. Furthermore, the maximum reflectance may be in the range of 20% to 55%, and increase the process margin within this range. In addition, the maximum reflectance may be in the range of 20% to 45%, within this range may maximize the light extraction efficiency of the light emitting diode and further increase the process margin.

The light emitting diode may further include a nuclear layer positioned between the substrate and the semiconductor stack, and the nuclear layer may be formed of AlN or Al 2 O 3.

Furthermore, the nuclear layer may be formed of Al 2 O 3, and the nuclear layer may cover the light scattering elements.

Meanwhile, the substrate may have protrusions under the light scattering elements, and the height of the protrusions is smaller than the height of the light scattering elements.

In one embodiment, the light scattering elements have a maximum width of the bottom surface greater than the height. Since the width of the lower surface is larger than the height, the amount of light emitted to the upper surface of the substrate can be increased. However, the present invention is not limited thereto, and in another embodiment, the light scattering elements may have a maximum width of a lower surface of the lower surface than a height.

The light emitting diode may further include a reflective layer under the substrate. The reflective layer may comprise a metal reflective layer or a distributed Bragg reflector.

Meanwhile, the size of the pointing vector on the upper surface side of the substrate may be four times greater than the size of the pointing vector on the side surface of the substrate.

In another embodiment, a light emitting diode includes: a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; A pattern of light scattering elements disposed between the substrate and the semiconductor stack, the light scattering elements including dielectric layers having different refractive indices, the light scattering elements having a bottom surface in contact with the substrate, and upwardly from the bottom surface. Increasingly narrower, the top of the light scattering element is curved or cusp.

The bandwidth of the reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices may be 40 nm or more, and the peak wavelength of the light emitted from the active layer may be located within the bandwidth.

Further, the maximum reflectance of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices may be in the range of 20% to 90%.

In another embodiment, a light emitting diode includes: a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; A pattern of light scattering elements disposed between the substrate and the semiconductor stack, wherein the light scattering elements comprise dielectric layers having different refractive indices, the light scattering elements contacting the substrate and the top facing the bottom surface. It includes, the width becomes narrower toward the top end from the lower surface, the width of the upper end is less than 1/10 of the width of the lower surface.

In one embodiment, the substrate is a sapphire substrate, the light scattering element comprises an SiO 2 layer and an Al 2 O 3 layer, and the Al 2 O 3 layer of the light scattering element may contact the substrate.

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a schematic cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a portion of FIG. 1 to explain a light scattering element, and FIG. Schematic perspective views for explaining various shapes.

First, referring to FIGS. 1 and 2, a light emitting diode according to the present embodiment includes a substrate 21, a light scattering element 23, a nuclear layer 25, a light emitting structure 30, an ohmic electrode 37, and a reflector. (41).

The substrate 21 may be an insulating or conductive substrate. The substrate 21 may be a growth substrate for growing the light emitting structure 30, and may include a sapphire substrate, a silicon carbide substrate, a silicon substrate, a gallium nitride substrate, an aluminum nitride substrate, and the like. In particular, the substrate 21 may have a smaller refractive index than gallium nitride, and may be, for example, a sapphire substrate.

In addition, the substrate 21 may have protrusions 21a positioned below the light scattering elements 23. The width of the protrusion 21a can be largely similar to the maximum width of the light scattering element 23. The protrusions 21a may be formed by overetching while patterning the light scattering elements 23. However, the height of the protrusions 21a is smaller than the height of the light scattering element 23. The planar shape of the protrusions 21a corresponds to the shape of the lower surfaces of the light scattering elements 23 described later.

The light scattering elements 23 are arranged regularly to form a pattern. The light scattering elements 23 can be arranged at a constant pitch with a constant bottom size. For example, the light scattering elements 23 can be arranged in a honeycomb shape. However, the present invention is not limited thereto, and the light scattering elements 23 may be arranged in various shapes such as a matrix shape.

The maximum width of the bottom surface of the light scattering element 23 may be greater than its height. For example, the bottom surface of the light scattering element 23 may be 1 to 5 um, and its height may be 0.5 to 3 um. In a specific embodiment, the light scattering elements 23 may have a conical shape, the diameter of the lower surface may be, for example, 2.7 μm and the height may be about 1.8 μm, and the light scattering elements 23 may have a pitch of about 3 μm. It can be arranged in a honeycomb shape.

However, the shape of the light scattering element 23 is not limited to a cone shape, and may have various shapes such as hemispherical shape or shell shape. Various shapes of the light scattering elements 23 are described with reference to FIG. 3.

First, referring to FIG. 3A, the light scattering element 23 may have a conical shape having a circular bottom surface. The width gradually narrows from the bottom to the top, and the side slope is constant. Although the diameter of the lower surface is shown as being smaller than the height in the figure, the diameter of the lower surface may be larger than the height.

Referring to FIG. 3B, the light scattering element 23 has a conical shape having a circular bottom surface and a convex side surface. Since the side surface has a convex shape, it is possible to increase the area where light is scattered compared to the conical shape.

Referring to FIG. 3C, the light scattering elements 23 may have a ballistic cone shape. That is, the light scattering element 23 has a circular shape at the bottom, a cylindrical shape at the bottom, and a cone on which the cone is placed.

Referring to FIG. 3 (d), the light scattering element 23 may have a triangular pyramid shape having a triangular lower surface. The lower surface may be, for example, an equilateral triangle, but is not necessarily limited thereto.

Referring to FIG. 3E, the light scattering element 23 may have a triangular pyramid shape, but a lower surface and a side surface thereof may be deformed. For example, as shown small on the right side, the bottom surface may be a shield shape, and the side surface may be a convex shape.

Referring to FIG. 3 (f), the light scattering elements 23 may be hemispherical in shape. The lower surface is circular in shape, the width becomes narrower upward from the lower surface, and the uppermost surface is curved.

Referring to FIG. 3G, the light scattering elements 23 may be shell type. The lower surface may have a circular shape, and the width becomes narrower upward from the lower surface, but has a relatively long shape rather than a hemispherical shape. Shell type can improve the light extraction efficiency by increasing the scattering area compared to the hemispherical shape.

Referring to FIG. 3 (h), the light scattering element 23 may have a shape in which an elliptic hemispherical shape and a cone shape are mixed. That is, the light scattering element 23 has a shape in which the cone is raised under the elliptic hemisphere.

The light scattering elements 23 may be formed by alternately stacking dielectric layers 23a and 23b having different refractive indices and then patterning them. For example, each light scattering element 23 may have a structure in which an SiO 2 layer (refractive index: about 1.48) and an Al 2 O 3 layer (refractive index: about 1.65) are alternately stacked. When the substrate 21 is a sapphire substrate, the Al 2 O 3 layer is suitable because it is the same material as the sapphire substrate 21. However, the present invention is not limited to a specific dielectric layer, and various dielectric layers having different refractive indices may be used.

On the other hand, the number of pairs of dielectric layers may be set in consideration of the thickness and reflectance of the light scattering element 23 required. In addition, the first dielectric layer 23a in contact with the substrate 21 may be a dielectric layer having a relatively low refractive index, or may be a dielectric layer having a relatively high refractive index. However, when the substrate 21 is a sapphire substrate (refractive index: about 1.78), the total internal reflection of light incident from the substrate 21 to the light emitting structure 30 can be reduced by using the dielectric layer having a small refractive index difference with the sapphire substrate as the first layer. have. For example, when the light scattering elements 23 are formed using dielectric layers 23a and 23b alternately stacked with an SiO 2 layer and an Al 2 O 3 layer, the sapphire substrate is formed by using the Al 2 O 3 layer as the first layer instead of the SiO 2 layer. The total internal reflection between the substrate 21 and the light scattering elements 23 can be reduced by reducing the difference in refractive index between the 21 and the light scattering elements 23. However, the present invention is not limited thereto, and the SiO 2 layer may be the first layer.

On the other hand, the last layer of the light scattering element 23 may be a high refractive index layer or a low refractive index layer. Since the Al 2 O 3 layer is advantageous for forming the gallium nitride based light emitting structure 30 formed thereon, the Al 2 O 3 layer can be used as the last layer. However, the present invention is not limited thereto, and the SiO 2 layer may be the last.

Meanwhile, in the embodiments shown in FIGS. 3A to 3H, the light scattering element 23 has a flat lower surface contacting the substrate 21, and the width becomes narrower from the lower surface upward. Has Furthermore, as shown in the above embodiments, the top of the light scattering element 23 may be curved or cusp. However, the present invention is not necessarily limited thereto, and the top may include a flat surface. Such flat surfaces may be formed intentionally or by process limitations in the process of forming hemispherical, shell or cones. However, in the embodiments of the present invention, the size of the flat surface formed at the top is extremely limited. In a particular embodiment, when the top of the light scattering element 23 comprises a flat surface, the top flat surface is, for example, 1/10 or less of the width of the bottom surface.

Since the light scattering element 23 has a shape that becomes narrower from the lower surface upward, the scattering effect by the light scattering element 23 can be increased. When the light scattering element 23 has a columnar shape or has a relatively wide top flat surface, the light emitted from the light emitting structure 30 enters the substrate 21, and then again the light emitting structure 30. It may be difficult to re-enter to the side. On the contrary, by adopting the light scattering element 23 of the present embodiment, the light entering the substrate 21 can easily escape back to the light emitting structure 30, so that the light extraction efficiency can be improved.

Meanwhile, when the same material layers as the dielectric layers 23a and 23b in the light scattering element 23 are deposited to the same thickness, they may have a structure of a distributed Bragg reflector having a band width of a reflection band. Further, the peak wavelength of the light emitted from the active layer 33 of the light emitting structure 30 is located within the bandwidth. In particular, the peak wavelength of the light may be located within ± 10% of the bandwidth from the center of the bandwidth region.

Meanwhile, the bandwidth of the reflection band of the distributed Bragg reflector may be 40 nm or more, further, 70 nm or more, and further, 90 nm or more.

The wider the bandwidth of the reflection band can increase the process margin can reduce the failure rate of the light emitting diode.

Meanwhile, the maximum reflectance of the distributed Bragg reflector may be in the range of 20% to 90%, further, in the range of 20% to 55%, further, in the range of 20% to 45%. In general, the distributed Bragg reflector is formed to have a reflectance of approximately 100%, and may also be arranged in a columnar shape on the substrate 21 to maintain the reflectance. However, when the light scattering elements 23 are formed in a columnar shape, it is difficult to extract the light entering the substrate 21, so that it is difficult to improve the light extraction efficiency. According to the present invention, the light scattering element 23 may be formed in a specific shape to lower the reflectance while maximizing the light scattering effect. In addition, light entering the substrate 21 may be extracted to the upper surface side of the light emitting structure 30 again. It can improve the light extraction efficiency.

Meanwhile, the nuclear layer 25 may be located between the substrate 21 and the semiconductor stack 30. In one embodiment, the nuclear layer 25 may be formed on the substrate 21 between the light scattering elements 23. In another embodiment, the nuclear layer 25 may cover the light scattering elements 23 and the substrate 21.

The nuclear layer 25 may be formed of, for example, AlN or Al 2 O 3. AlN is well known as a nuclear layer for growing a nitride based semiconductor layer. Meanwhile, Al 2 O 3 may be recrystallized by heat treatment with the same material as the sapphire substrate 21, and thus, may be used as a nuclear layer for growing a nitride-based semiconductor layer.

The light emitting structure 30 is located on the substrate 21. The light emitting structure 30 also covers the light scattering elements 23. The light emitting structure 30 may include a first conductive semiconductor layer 31, a second conductive semiconductor layer 35 positioned on the first conductive semiconductor layer 21, and a first conductive semiconductor layer 31. The active layer 33 is positioned between the second conductive semiconductor layer 35. The overall thickness of the light emitting structure 30 may be in the range of about 5-10 μm.

Meanwhile, the first conductive semiconductor layer 31, the active layer 33, and the second conductive semiconductor layer 35 may include III-V-based nitride semiconductors, for example, (Al, Ga, In Nitride-based semiconductors such as N). The first conductive semiconductor layer 31 may include n-type impurities (eg, Si, Ge. Sn), and the second conductive semiconductor layer 35 may include p-type impurities (eg, Mg, Sr, Ba). It may also be the reverse. The active layer 33 may include a multi-quantum well structure (MQW), and the composition ratio of the nitride semiconductor may be adjusted to emit a desired wavelength. In particular, in the present embodiment, the second conductivity-type semiconductor layer 35 may be a p-type semiconductor layer.

On the other hand, the ohmic electrode 37 is located on the second conductivity type semiconductor layer 35. The ohmic electrode 37 may ohmic contact the second conductive semiconductor layer 35. The ohmic electrode 37 may include, for example, indium tin oxide (ITO), zinc oxide (ZnO), zinc indium tin oxide (ZITO), zinc indium oxide (ZIO), zinc tin oxide (ZTO), gallium indium tin (GITO). It may include a light-transmitting conductive oxide layer, such as oxide (Gide), gallium indium oxide (GIO), gallium zinc oxide (GZO), aluminum doped zinc oxide (AZO), fluorine tin oxide (FTO). The conductive oxide may include various dopants.

The ohmic electrode 37 including the light transmissive conductive oxide has excellent ohmic contact characteristics with the second conductivity type semiconductor layer 35 and can transmit light. However, the present invention is not limited thereto, and the ohmic electrode 37 may include a metal layer.

The thickness of the ohmic electrode 37 is not limited, but if the thickness is excessively thick, light loss due to light absorption may occur. Therefore, the thickness of the ohmic electrode 37 is limited to approximately 3000 kPa or less.

The reflector 41 is positioned below the substrate 21. The reflector 41 may include a metal reflective layer such as Ag, Al, Au, or a distributed Bragg reflector. The reflector 41 reflects the light that passes through the substrate 21 and proceeds downward to the substrate 21 toward the upper surface of the substrate 21.

The reflector 41 may be a distributed Bragg reflector formed by repeatedly stacking dielectric layers having different refractive indices, and the dielectric layers may include TiO _{2 ,} SiO ₂ , HfO ₂ , ZrO ₂ , Nb ₂ O ₅ , MgF ₂ , and the like. . For example, the reflector 41 may have a structure of alternately stacked TiO ₂ layers / SiO ₂ layers. The distributed Bragg reflector used in the reflector 41 may have, for example, a reflectance of at least 90%, furthermore at least 95%, for the light generated in the active layer 33.

The insulating layer 37 may have a thickness of about 2 μm to 5 μm. The distributed Bragg reflector may have a reflectance of 90% or more with respect to the light generated in the active layer 33, and the reflectivity close to 100% may be provided by controlling the type, thickness, lamination period, etc. of the plurality of dielectric layers forming the distributed Bragg reflector. Can be. Moreover, the distributed Bragg reflector may have a high reflectance for visible light other than the light generated in the active layer 33.

In the present embodiment, the light emitting diode may be a horizontal light emitting diode, and light generated in the active layer 33 is generally transmitted through the ohmic electrode 37 and emitted to the outside. In particular, the amount of light emitted to the upper surface side of the substrate 21 may be four times or more than the amount of light emitted to the side surface of the substrate 21.

However, the present invention is not limited to the horizontal light emitting diode, and may be a flip chip light emitting diode. In this case, the ohmic electrode 37 may include a reflector, and the reflector 41 is omitted.

4 is a simulation graph for explaining reflectance and reflection band according to deposition conditions of dielectric layers for forming a light scattering element.

First, in order to confirm the refractive indices of the SiO 2 layer and the Al 2 O 3 layer under actual deposition conditions, these layers were respectively deposited on the substrates to measure optical properties, and the refractive indices were calculated therefrom. As a result, the refractive index of the SiO 2 layer was 1.4824, and the refractive index of the Al 2 O 3 layer was 1.65341. On the other hand, the refractive index of the sapphire substrate is about 1.78, which is higher than that of the Al2O3 layer.

In a structure in which 15 pairs of SiO 2 (refractive index: 1.48) / Al 2 O 3 (refractive index: 1.65) are alternately stacked on a sapphire substrate (refractive index: 1.78), the thickness of each layer is adjusted to reflect the band width of the reflection band and the reflectance at 460 nm. Was adjusted.

The stacked structure of each of the embodiments presented herein corresponds to the stacked structure before patterning to form light scattering elements (23 of FIG. 1).

As can be seen in Figure 4, the higher the reflectance, the narrower the width of the band, when adjusting the thickness to increase the band width, the reflectance decreases. Bandwidths for each reflectance are summarized in Table 1. Here, the band width means the half width in the reflection band.

reflectivity(%) 90 75 55 45 35 20 Bandwidth (nm) 43 54 76 97 95 110

In consideration of the performance of the light emitting diode, it may be advantageous to form the light scattering element 23 using a laminated structure having a high reflectance. However, the peak wavelength of the light emitted from the light emitting diodes or the optical characteristics of the dielectric layers forming the light scattering elements may experience various fluctuations in the process of manufacturing the light emitting diodes. Therefore, in consideration of the process margin of the light emitting diode, it is necessary to use a laminated structure having a wide band width. As the band width of the reflection band is wider, the yield of the light emitting diode can be improved. Therefore, the band width of the reflection band includes the peak wavelength of light generated in the active layer 33 and should be at least 40 nm or more, and further, a wider band width may be required.

5 is a graph illustrating a pointing vector value according to the prior art and various embodiments of the present disclosure. The pointing vector value represents the energy flow through the unit area per unit time, and thus, the flow of energy emitted from the light emitting diode can be compared by comparing the pointing vector value.

The structure of the light emitting diode used in the simulation was similar to that of FIG. 1, and the conical light scattering elements having a diameter of 2.7 μm were arranged in a honeycomb with a pitch of 3.0 μm by patterning the stacked structures described in FIG. 4 on the sapphire substrate. The thickness of the light scattering elements was in the range of 2.0 to 2.4 um. In addition, the total thickness of the light emitting structure was set to 7.1 um, 48 nm thick ITO was used as the ohmic electrode, and 300 nm thick Ag reflector was set below the substrate. Pointing vector values on the side and top surfaces of the substrate were calculated through finite-difference time-domain (FDTD) simulations of the structure of the light emitting diode, and each pointing vector value and the total pointing vector value were shown in a graph. On the other hand, the simulation was similarly performed on the conventional patterned sapphire substrate (PSS), wherein the conical protrusions formed on the sapphire substrate were 2.7 um in diameter, 1.8 um in height, and 3.0 um in pitch, and the rest of the structure was the same. Set to.

Referring to FIG. 5, the comparative example using the conventional patterned sapphire substrate (ref.) Showed a high pointing vector value at the side of the substrate. Meanwhile, the embodiments of the present invention using the light scattering elements showed a higher pointing vector value on the upper surface of the substrate and a higher total pointing vector value than the comparative example.

In particular, the best pointing vector value was shown in the embodiment having a light scattering element formed by patterning a laminated structure with a reflectance of 20%.

Table 2 shows the ratio of the pointing vector value increase rate of the present examples to the comparative example and the pointing vector value on the upper surface side of the substrate relative to the side surface of the substrate.

Ref. R90% R75% R55% R45% R35% R20% % Growth 0.0 10.4 16.4 8.0 11.3 12.3 16.8 Top: Side 3.3: 1 4.5: 1 4.6: 1 4.2: 1 4.7: 1 4.5: 1 4.5: 1

Referring to Table 2, the examples show an increase rate of the pointing vector value of 10% or more compared to most of the comparative examples. In addition, the ratio of the pointing vector value on the substrate upper surface side to the substrate side surface was 3.3: 1 in the comparative example, but all of the examples exceeded 4: 1.

Therefore, it can be seen that the embodiments of the present invention have improved light extraction efficiency toward the upper surface of the substrate compared to the comparative example.

In the above-described embodiment, the light emitting diode chip and the light emitting device according to various embodiments of the present invention have been described, but the present invention is not limited thereto. The light emitting diode chip may be applied to various other electronic devices requiring a small light emitting unit, for example, to a display device.

Claims (21)

Board;
A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer;
A pattern of light scattering elements disposed between the substrate and the semiconductor stack,
The light scattering element includes dielectric layers having different refractive indices and has a hemispherical shape, a shell shape, or a cone shape. The method according to claim 1,
The light scattering element has a cone shape of a light emitting diode including a conical shape, a triangular pyramid shape, a convex side shape, a shield shape and a convex side shape triangular pyramid, a ballistic cone shape, or a ballistic cone shape having a lower side convex. . The method according to claim 1,
The bandwidth of the reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices is 40 nm or more,
The peak wavelength of light emitted from the active layer is located within the bandwidth. The method according to claim 3,
Wherein the peak wavelength of the light is within ± 10% of the bandwidth from the center of the bandwidth region. The method according to claim 3,
And a band width of a reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices. The method according to claim 5,
And a band width of a reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices of 90 nm or more. The method according to claim 1,
And a maximum reflectance of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices in the range of 20% to 90%. The method according to claim 7,
Wherein the maximum reflectance of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices is in the range of 20% to 55%. The method according to claim 8,
And a maximum reflectance of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices in the range of 20% to 45%. The method according to claim 1,
Further comprising a nuclear layer located between the substrate and the semiconductor stack,
The nuclear layer is a light emitting diode formed of AlN or Al2O3. The method according to claim 10,
The nuclear layer is formed of Al2O3,
And the nuclear layer covers the light scattering elements. The method according to claim 1,
The substrate has protrusions under the light scattering elements, the height of the protrusions being less than the height of the light scattering elements. The method according to claim 1,
And the light scattering elements have a maximum width at a lower surface than a height. The method according to claim 1,
The light emitting diode further comprises a reflective layer positioned below the substrate. The method according to claim 14,
The reflective layer includes a metal reflective layer or a distributed Bragg reflector. The method according to claim 1,
Wherein the size of the pointing vector on the upper surface side of the substrate is four times greater than the size of the pointing vector on the side surface of the substrate. Board;
A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer;
A pattern of light scattering elements disposed between the substrate and the semiconductor stack,
The light scattering element includes dielectric layers having different refractive indices,
The light scattering element has a bottom surface in contact with the substrate, the width of the light scattering element is narrowed upward from the bottom surface, the top of the light scattering element is a curved surface or a peak. The method according to claim 17,
The bandwidth of the reflection band of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices is 40 nm or more,
The peak wavelength of light emitted from the active layer is located within the bandwidth. The method according to claim 18,
And a maximum reflectance of the distributed Bragg reflector having the same material layers and the same thicknesses as the dielectric layers having different refractive indices in the range of 20% to 90%. Board;
A semiconductor stack disposed on the substrate, the semiconductor stack including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer;
A pattern of light scattering elements disposed between the substrate and the semiconductor stack,
The light scattering element includes dielectric layers having different refractive indices,
The light scattering element includes a lower surface in contact with the substrate and an uppermost end facing the lower surface, the width of which is narrowed toward the uppermost end from the lower surface, wherein the uppermost width is 1/10 or less of the width of the lower surface. The method of claim 20,
The substrate is a sapphire substrate,
The light scattering element comprises an SiO 2 layer and an Al 2 O 3 layer,
And an Al 2 O 3 layer of the light scattering element in contact with the substrate.

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