TWI591854B - Light-emitting diode including porous transparent electrode - Google Patents

Description

Light-emitting diode including porous transparent electrode

The present invention relates to a light emitting diode, and more particularly to a light emitting diode including a porous transparent electrode to improve light extraction efficiency.

In general, a light-emitting diode refers to a semiconductor device that directly converts a current into light based on the principle of emitting light by a combination of electrons from the n region and holes from the p region when a voltage is applied to the semiconductor p-n junction. Light-emitting diodes due to various advantages such as good energy conversion efficiency, long service life and good directionality of light, low operating voltage, no need for warm-up time or complex drive circuit, and good shock and vibration resistance As a next-generation light source capable of replacing an existing light source such as an incandescent lamp, a fluorescent lamp, a mercury lamp, or the like, attention has been paid.

The illumination efficiency of a light-emitting diode generally depends on internal quantum efficiency and light extraction efficiency. Specifically, the light extraction efficiency refers to the ratio of the number of photons released to the outside of the light-emitting diode (ie, free space) to the number of photons emitted by the active layer, and although the internal quantum efficiency of the light-emitting diode is high, the light-emitting diode The low light extraction efficiency of the volume results in a reduction in the number of photons released into the free space, resulting in a significant reduction in the efficiency of the light-emitting diode as a light source in practice.

In a typical light-emitting diode, air (n air = 1.0), GaN-based substrate (nGaN = 2.4), sapphire substrate (nsapphire = 1.77), and ITO electrode (nITO =) are provided on the path of light transmission to free space. 1.9) The refractive index at the interface between the two is different, so total internal reflection occurs, which traps a large amount of light, resulting in a significant decrease in light extraction efficiency.

For example, as shown in FIG. 1, the light L1, L2 emitted from the active layer 2b is released to the outside through the upper semiconductor layer 2c and the transparent electrode 3. In the case where the upper semiconductor layer 2c is made of p-type GaN, and the transparent electrode 3 is made of indium tin oxide (ITO), light is refracted at the interface due to the difference in refractive index. In this case, when the angle of refraction of the light passing through the interface between the transparent electrode 3 and the air is less than or equal to the critical angle, the light may be emitted to the outside, and when the angle of refraction of the light (such as the light L2) is greater than the critical angle Light will be trapped inside the interface instead of escaping to the outside. Therefore, due to total internal reflection, a large amount of light is trapped in the light-emitting diode, resulting in a significant decrease in light extraction efficiency of the light-emitting diode.

In order to effectively reduce total internal reflection and improve light extraction efficiency, various efforts have been made, for example, etching a light emitting diode to form a structure that facilitates light release, changing a wafer structure of a light emitting diode, removing a reflective plate, and a transparent electrode. Surface patterning and more.

However, the surface patterning of the transparent electrode layer is usually performed by a process such as electron beam lithography, and electron beam lithography is difficult to form for forming a large-sized light-emitting diode, and the process cost is increased. Further, when the surface of the transparent electrode layer is subjected to high-energy patterning such as electron beam lithography, the semiconductor layer of the light-emitting diode may be damaged by high energy, resulting in a decrease in reliability of the light-emitting diode.

The exemplary embodiment provides a light emitting diode that can effectively reduce total internal reflection of light to improve light extraction efficiency.

According to an exemplary embodiment, a light emitting diode includes: a light emitting structure including a first conductive type semiconductor layer, an active layer disposed on the first conductive type semiconductor layer, and a second conductive type semiconductor disposed on the active layer a first transparent electrode layer disposed on the light emitting structure to cover a portion of the light emitting structure and having a plurality of air gaps in the first transparent electrode layer; and a second transparent electrode layer disposed on the first transparent electrode layer And having a plurality of air gaps formed in the second transparent electrode layer, the number or size of air gaps formed in the second transparent electrode layer being larger or larger than the number of air gaps formed in the first transparent electrode layer And an electrode disposed on the second transparent electrode layer corresponding to the position of the first transparent electrode layer, wherein the first transparent electrode layer has a higher specific resistance than the second transparent electrode layer.

The first transparent electrode layer or the second transparent electrode layer may be formed of zinc oxide (ZnO), and the light emitting diode may further include a photodiode formed between the light emitting structure and the first transparent electrode layer A tunnel junction layer and includes at least one of nickel oxide (NiO), gallium oxide (Ga ₂ O ₃ ), and magnesium oxide (MgO). The electrode may be partially embedded in the second transparent electrode layer.

The light emitting diode may further include a third transparent electrode layer interposed between the first transparent electrode layer and the second transparent electrode layer and the light emitting structure, and have a plurality of air gaps formed in the third transparent electrode layer, wherein the first transparent electrode layer has a higher specific resistance than the third transparent electrode layer.

The first transparent electrode layer may be formed in a predetermined pattern on the light emitting structure, and the predetermined pattern of the first transparent electrode layer may have at least one shape selected from the group consisting of a circle, a hexagon, a square, and a triangle. The light emitting diode may further include an electrode extension extending from the electrode, wherein a pattern of the first transparent electrode layer may correspond to a shape of the electrode and the electrode extension.

In each of the first transparent electrode layer and the second transparent electrode layer, the number or size of the air gap may gradually increase from the light emitting structure toward the electrode.

According to an exemplary embodiment, the light emitting diode includes a transparent electrode layer having an air gap, the number and size of the air gap gradually increasing in an upward direction, thereby gradually decreasing the refractive index along the transparent electrode layer Thereby increasing the light extraction rate of the light-emitting diode.

Further, the light emitting diode includes an electrode formed on the transparent electrode layer or at a portion formed by partially etching the transparent electrode layer, thereby facilitating vertical current spreading.

Further, the current blocking layer is formed of the same material as the transparent electrode layer while adjusting its specific resistance to reduce light loss by preventing light emitted from the light emitting structure from being reflected by the current blocking layer, and is formed in the On the transparent electrode layer to allow for more efficient current spreading.

10‧‧‧Base

20‧‧‧Lighting structure

21‧‧‧First Conductive Semiconductor Layer

23‧‧‧Active layer

25‧‧‧Second conductive semiconductor layer

30‧‧‧Transparent electrode layer

31‧‧‧First transparent electrode layer

33‧‧‧Second transparent electrode layer

35‧‧‧ third transparent electrode layer

41‧‧‧First electrode

43‧‧‧second electrode

43a‧‧‧Electrode extension

G‧‧‧ air gap

1 is a cross-sectional view of a typical light emitting diode.

2 is a cross-sectional view of a light emitting diode according to a first exemplary embodiment.

3(a) to 3(c) are cross-sectional views of a transparent electrode layer of a light emitting diode according to the first exemplary embodiment and a modification thereof.

4(a) to 4(c) are cross-sectional views of a transparent electrode layer of a light-emitting diode and a modification thereof according to a second exemplary embodiment.

5(a) to 5(d) are cross-sectional views of a transparent electrode layer of a light-emitting diode and a modification thereof according to a third exemplary embodiment.

Fig. 6 is a plan view showing one example of a first transparent electrode layer of a light emitting diode according to the third exemplary embodiment.

The exemplary embodiments will be described in detail below with reference to the drawings.

2 is a cross-sectional view of a light emitting diode according to a first exemplary embodiment, and FIG. 3(a) is an enlarged cross-sectional view of a transparent electrode layer of the light emitting diode according to the first exemplary embodiment.

Referring to FIG. 2, the light emitting diode according to the first exemplary embodiment includes a substrate 10, a light emitting structure 20, a transparent electrode layer 30, a first electrode 41, and a second electrode 43.

For the substrate 10, any substrate may be used without limitation as long as the substrate allows the light-emitting structure 20 to grow thereon. In certain exemplary embodiments, the substrate 10 can be a sapphire substrate, a SiC substrate, a spinel substrate, a Si substrate, or a gallium nitride substrate. In certain exemplary embodiments, the substrate 10 can have a predetermined pattern formed on its upper surface, similar to a patterned sapphire substrate (PPS). Although not shown in FIG. 2, the light emitting diode may further include a buffer layer formed on the substrate 10 to serve as a core layer for growth of the light emitting structure 20, thereby improving the light emitting structure The crystallinity of each of the semiconductor layers of 20.

The light emitting structure 20 is disposed on the substrate 10 and includes a first conductive type semiconductor layer 21, an active layer 23, and a second conductive type semiconductor layer 25. The second conductive type semiconductor layer 25 is disposed on the first conductive type semiconductor layer 21 and the active layer 23 may be interposed between the first conductive type semiconductor layer 21 and the second conductive type semiconductor layer 25 between.

Each of the first conductive type semiconductor layer 21 and the second conductive type semiconductor layer 25 may include a III-V compound semiconductor, for example, a nitride-based semiconductor such as (Al, Ga, In) N. The first conductive type semiconductor layer 21 may include an n-type semiconductor layer doped with an n-type dopant such as Si, and the second conductive type semiconductor layer 25 may include a p-type doped with a p-type dopant such as Mg Semiconductor layer. It is apparent that these dopants for the first conductive type semiconductor layer 21 and the second conductive type semiconductor layer 25 are also interchangeable.

In addition, each of the first conductive type semiconductor layer 21 and the second conductive type semiconductor layer 25 may be composed of a single layer or a plurality of layers. For example, the first conductive type semiconductor layer 21 and/or the second conductive type semiconductor layer 25 may include a cover layer and a contact layer, and may further include a superlattice layer.

The active layer 23 may include a multi-quantum well (MQW) structure, and the elements constituting the multiple quantum well structure and its components may be adjusted to allow the multiple quantum well structure to emit light having a desired peak wavelength. For example, the well layer of the active layer 23 may be a ternary semiconductor layer such as InGaN or a quaternary semiconductor layer such as AlInGaN, in which the composition ratio of the components may be adjusted to emit light having a desired peak wavelength.

Each of the first conductive type semiconductor layer 21, the active layer 23, and the second conductive type semiconductor layer 25 may be passed through, for example, metal organic chemical vapor deposition (metal organic chemical) Vapor deposition (MOCVD), molecular beam epitaxy (MBE) or hydride vapor phase epitaxy (HVPE) techniques are used to grow on growth substrates. The first conductive type semiconductor layer 21 may be patterned by a lithography and etching process to expose some of the regions.

The transparent electrode layer 30 is disposed on the second conductive type semiconductor layer 25. The transparent electrode layer 30 is used to increase the light-emitting area by dispersing a current transmitted to the light-emitting diode, and in the first exemplary embodiment, the transparent electrode layer 30 may include a conductive material such as ZnO.

As shown in FIG. 2, in the first exemplary embodiment, the transparent electrode layer 30 includes a plurality of air gaps G. As shown in FIG. 2, in the present exemplary embodiment, the air gaps G formed in the transparent electrode layer 30 are filled with air, and may be separated from each other or connected to each other. The air gap G may have a circular or hexagonal cross section.

As shown in FIG. 3(a), in the present exemplary embodiment, an air gap G may be formed in the transparent electrode layer 30 such that the number or size of the air gap G is from the lower side of the transparent electrode layer 30 to the upper side thereof (along The direction from the second conductive type semiconductor layer 25 to the second electrode 43 is gradually increased. In this manner, the air gap G is formed in the transparent electrode layer 30 while adjusting the density of the air gap G such that the number or size of the air gap gradually increases from the lower side of the transparent electrode layer 30 to the upper side thereof, thereby improving the light emitting diode Light extraction efficiency of the body.

Also, the air gap G is formed in the transparent electrode layer 30 such that the number or size of the air gap gradually increases from the lower side of the transparent electrode layer 30 to the upper side thereof, thereby minimizing total internal reflection of the light emitting diode. As the number or size of the air gaps G in the transparent electrode layer 30 increases, the refractive index inside the transparent electrode layer 30 decreases.

In the present exemplary embodiment, a sol-gel prepared by mixing a nanostructure A (sol-gel) material is used to form an air gap in the transparent electrode layer 30. Here, a sol-gel material is formed by mixing a nanostructure with ZnO, which is used as a raw material of the transparent electrode layer 30 in the first exemplary embodiment. Here, the nanostructure may be a nanosphere having a particle diameter of 0.1 um to 3 um. As in the first exemplary embodiment, the distribution of the nanostructures may be adjusted according to the position of the transparent electrode layer 30 to obtain a desired number or size of the air gaps G. Then, the nanostructure can be removed by selectively using helium to form a plurality of air gaps in the transparent electrode layer 30.

Referring again to FIG. 2, the second electrode 43 is formed on the transparent electrode layer 30, and the first electrode 41 is disposed on the exposed region of the first conductive type semiconductor layer 21. Therefore, the second electrode 43 is electrically connected to the second conductive type semiconductor layer 25 through the transparent electrode layer 30, and the first electrode 41 is electrically connected to the first conductive type semiconductor layer 21.

Although the first exemplary embodiment has been described with reference to a lateral type light emitting diode, it should be understood that the present disclosure is not limited thereto, and other implementations are possible. In a further exemplary embodiment, the vertical light emitting diode includes a transparent electrode layer 30 having an air gap G formed therein to minimize total internal reflection, thereby improving light extraction efficiency.

According to the first exemplary embodiment, the light emitting diode may further include a tunnel junction layer (not shown) between the light emitting structure 20 and the transparent electrode layer 30. A thin thickness tunnel junction layer is formed on the light emitting structure 20 to improve ohmic contact between the transparent electrode layer 30 and the light emitting structure 20, and the tunnel junction layer may include at least one of NiO, Ga ₂ O _{3 ,} and MgO.

Fig. 3 (b) is a cross-sectional view showing a modification of the transparent electrode layer of the light emitting diode according to the first exemplary embodiment.

As shown in FIG. 3(b), in this modification of the first exemplary embodiment, The bright electrode layer 30 includes a first transparent electrode layer 31 and a second transparent electrode layer 33. The first transparent electrode layer 31 may be disposed on the second conductive type semiconductor layer 25, and the second transparent electrode layer 33 may be disposed on the first transparent electrode layer 31. Here, the second transparent electrode layer 33 may have an air gap G of a larger number or larger size than the first transparent electrode layer 31. Therefore, the number or size of the air gap G gradually increases in the upward direction. Further, the transparent electrode layer may include a third transparent electrode layer, which may be formed on the second transparent electrode layer 33 and have a larger or larger size than the second transparent electrode layer 33, as needed G.

In this modification of the first exemplary embodiment, the second electrode 43 may be formed on the second transparent electrode layer 33 and electrically connected to the second conductive type semiconductor layer 25.

Fig. 3 (c) is a cross-sectional view showing another modification of the transparent electrode layer of the light emitting diode according to the first exemplary embodiment.

As shown in FIG. 3(c), in this modification of the first exemplary embodiment, the transparent electrode layer 30 may be formed such that the number or size of the air gap G is from the lower side to the upper side of the transparent electrode layer (along the slave The direction from the second conductive type semiconductor layer 25 to the second electrode 43 is gradually increased. In addition, the transparent electrode layer 30 may be partially removed by etching such that the second electrode 43 is partially embedded in the transparent electrode layer 30. In this manner, with a structure in which the second electrode 43 is disposed on the etched region of the transparent electrode layer 30 formed by partial etching, the length of the current path can be lowered in the vertical direction, thereby providing a current expansion. advantage.

4(a) is a cross-sectional view of a transparent electrode layer of a light emitting diode according to a second exemplary embodiment.

The light emitting diode according to the second exemplary embodiment includes a substrate 10, a light emitting structure 20, a first transparent electrode layer 31, a second transparent electrode layer 33, a first electrode 41, and a second electrode 43. Description of the same features as those in the first exemplary embodiment will be omitted.

As shown in FIG. 4(a), the first transparent electrode layer 31 is disposed on the second conductive type semiconductor layer 25 of the light emitting structure 20. Here, the first transparent electrode layer 31 may be formed only on some regions of the second conductive type semiconductor layer 25. Further, a second transparent electrode layer 33 is formed on the second conductive type semiconductor layer 25 to cover the first transparent electrode layer 31.

In the exemplary embodiment, the first transparent electrode layer 31 has a higher specific resistance than the second transparent electrode layer 33, and each of the first transparent electrode layer 31 and the second transparent electrode layer 33 contains ZnO The ZnO of the first transparent electrode layer 31 is made to have a higher specific resistance than the ZnO of the second transparent electrode layer 33. The second electrode 43 is formed on the second transparent electrode layer 33 above the first transparent electrode layer 31. With this configuration, the first transparent electrode layer 31 functions as a current blocking layer (CBL) in the second exemplary embodiment.

In a structure in which both the first transparent electrode layer 31 and the second transparent electrode layer 33 comprise the same material, that is, ZnO, and the first transparent electrode layer 31 has a higher specific resistance than the second transparent electrode layer 33, the current may be The current blocking layer flows along the vertical direction of the second electrode 43, thereby achieving more efficient current spreading.

Further, as in the first exemplary embodiment, the air gap G may be formed in the second transparent electrode layer 33 such that the number or size of the air gap G is from the lower side of the second transparent electrode layer to the upper side thereof (along the slave The direction from the second conductive type semiconductor layer 25 to the second electrode 43 is gradually increased.

The light emitting diode according to the second exemplary embodiment may further include a tunnel junction layer (not shown) between the light emitting structure 20 and the first transparent electrode layer 31 and the second transparent electrode layer 33. A thin junction tunnel junction layer is formed on the light emitting structure 20 to improve ohmic contact between the first transparent electrode layer 31 and the second transparent electrode layer 33 and the light emitting structure 20, and the tunnel junction layer may include NiO, Ga ₂ O At least one of ₃ and MgO.

4(b) is a cross-sectional view showing a modification of the transparent electrode layer of the light emitting diode according to the second exemplary embodiment.

As shown in FIG. 4(b), in this modification of the second exemplary embodiment, the transparent electrode layer 30 includes a first transparent electrode layer 31, a second transparent electrode layer 33, and a third transparent electrode layer 35.

The third transparent electrode layer 35 is disposed on the second conductive type semiconductor layer 25 of the light emitting structure 20, and the first transparent electrode layer 31 is formed on some regions of the third transparent electrode layer 35. The second transparent electrode layer 33 is formed on the third transparent electrode layer 35 to cover the first transparent electrode layer 31. Therefore, the second transparent electrode layer 33 is in contact with a region of the third transparent electrode layer 35 where the first transparent electrode layer 31 is not formed.

The second transparent electrode layer 33 has a larger number or larger size of the air gap G than the third transparent electrode layer 35. Further, the first transparent electrode layer 31 is formed to have a higher specific resistance than the second transparent electrode layer 33 and the third transparent electrode layer 35. In this modification of the second exemplary embodiment, since the first transparent electrode layer 31, the second transparent electrode layer 33, and the third transparent electrode layer 35 contain ZnO, the first transparent electrode layer 31 functions as a current blocking layer. That is, the second electrode 43 is formed on the second transparent electrode layer 33 above the first transparent electrode layer 31.

A tunnel junction layer (not shown) may be interposed between the third transparent electrode layer 35 and the light emitting structure 20.

4(c) is a cross-sectional view showing another modification of the transparent electrode layer of the light emitting diode according to the second exemplary embodiment.

As shown in FIG. 4(c), the second transparent electrode layer 33 is partially removed by etching to expose a portion of the first transparent electrode layer 31, and the second electrode 43 is exposed at the first transparent electrode layer 31. Out of the area. In this configuration, the second electrode 43 is in direct contact with the first transparent electrode layer 31. As described above, since the first transparent electrode layer 31 contains ZnO, current can flow through the first transparent electrode layer 31 in the vertical direction. Since current can flow in the vertical direction of the second electrode 43, current spreading in the level direction becomes more effective.

Fig. 5(a) is a cross-sectional view of a transparent electrode layer of a light emitting diode according to a third exemplary embodiment.

As shown in FIG. 5(a), the transparent electrode layer 30 of the light emitting diode according to the third exemplary embodiment includes a first transparent electrode layer 31 and a second transparent electrode layer 33. In addition, the first transparent electrode layer 31 is formed on the second conductive type semiconductor layer 25 of the light emitting structure 20 in a predetermined pattern. The first transparent electrode layer 31 is formed on some regions of the second conductive type semiconductor layer 25 or formed over the entire region thereof.

In the exemplary embodiment, the first transparent electrode layer 31 may be formed on the second conductive type semiconductor layer 25 in a pattern having at least one shape selected from the group consisting of a circular shape, a hexagonal shape, a quadrangular shape, and a triangular shape. Further, the pattern of the first transparent electrode layer 31 can be changed in various ways as needed. A modification of the pattern of the first transparent electrode layer 31 will be described below.

The second transparent electrode layer 33 is formed to cover the first transparent electrode layer 31 having the pattern formed thereon. Therefore, the second transparent electrode layer 33 is formed to cover the first transparent electrode layer 31 while the second transparent electrode layer 33 is in contact with a portion of the second conductive type semiconductor layer 25. The second electrode 43 is formed on the second transparent electrode layer 33. In which the first transparent electrode layer 31 In the structure formed on the entire region of the second conductive type semiconductor layer 25, the first transparent electrode layer 31 may be formed at any position on the second transparent electrode layer 33. Conversely, in the structure in which the first transparent electrode layer 31 is formed on some regions of the second conductive type semiconductor layer 25, the second electrode 43 may be formed on the second transparent electrode layer 33 above the first transparent electrode layer 31. .

With this configuration, the first transparent electrode layer 31 functions as a current blocking layer (CBL). To this end, the first transparent electrode layer 31 contains ZnO, and the specific resistance of the first transparent electrode layer 31 is higher than the specific resistance of the second transparent electrode layer 33. Therefore, the current can easily pass through the first transparent electrode layer 31 formed of ZnO and having a predetermined pattern, so that current spreading can be facilitated.

Further, an air gap G may be formed in the second transparent electrode layer 33 such that the number or size of the air gap G is from the lower side of the second transparent electrode layer to the upper side thereof (along from the second conductive type semiconductor layer 25 to the second The direction of the electrode 43 is gradually increased.

The light emitting diode according to the second exemplary embodiment may further include a tunnel junction layer (not shown) between the light emitting structure 20 and the first transparent electrode layer 31 and the second transparent electrode layer 33. A thin junction tunnel junction layer is formed on the light emitting structure 20 to improve ohmic contact between the first transparent electrode layer 31 and the second transparent electrode layer 33 and the light emitting structure 20, and the tunnel junction layer may include NiO, Ga ₂ O At least one of ₃ and MgO.

Fig. 5 (b) is a cross-sectional view showing a modification of the transparent electrode layer of the light emitting diode according to the third exemplary embodiment.

As shown in FIG. 5(b), in this modification of the third exemplary embodiment, the transparent electrode layer 30 includes a first transparent electrode layer 31 and a second transparent electrode layer 33. The second transparent electrode layer 33 is partially removed by etching to expose the first transparent electrode having a predetermined pattern A portion of the layer 31, and the second electrode 43 is formed on the exposed region of the first transparent electrode layer 31. In this configuration, the second electrode 43 may be in contact with a portion of the first transparent electrode layer 31 exposed.

Further, an air gap G may be formed in the second transparent electrode layer 33 such that the number or size of the air gap G is from the lower side of the second transparent electrode layer to the upper side thereof (along from the second conductive type semiconductor layer 25 to the second The direction of the electrode 43 is gradually increased.

Fig. 5 (c) is a cross-sectional view showing another modification of the transparent electrode layer of the light emitting diode according to the third exemplary embodiment.

As shown in FIG. 5(c), in this modification of the third exemplary embodiment, the transparent electrode layer 30 includes a first transparent electrode layer 31, a second transparent electrode layer 33, and a third transparent electrode layer 35.

The third transparent electrode layer 35 is disposed on the second conductive type semiconductor layer 25 of the light emitting structure 20, and the first transparent electrode layer 31 is formed on the third transparent electrode layer 35 in a predetermined pattern. In this modification of the third exemplary embodiment, the first transparent electrode layer 31 is formed on some regions of the third transparent electrode layer 35 or on the entire region of the third transparent electrode layer 35. The second transparent electrode layer 33 is formed on the third transparent electrode layer 35 to cover the first transparent electrode layer 31. Therefore, the second transparent electrode layer 33 is in contact with a region of the third transparent electrode layer 35 where the first transparent electrode layer 31 is not formed.

In this modification of the third exemplary embodiment, the first transparent electrode layer 31 may be formed on the third transparent electrode layer 35 in at least one shape selected from the group consisting of a circular shape, a hexagonal shape, a quadrangular shape, and a triangular shape. Further, the pattern of the first transparent electrode layer 31 can be changed in various ways as needed.

The second electrode 43 is formed on the second transparent electrode layer 33. In the structure in which the first transparent electrode layer 31 is formed over the entire region of the second conductive type semiconductor layer 25, the first transparent electrode layer 31 may be formed at any position on the second transparent electrode layer 33. In contrast, in the structure in which the first transparent electrode layer 31 is formed on some regions of the second conductive type semiconductor layer 25, the second electrode 43 may be formed on the second transparent electrode layer 33 above the first transparent electrode layer 31.

With this configuration, the first transparent electrode layer 31 functions as a current blocking layer (CBL). To this end, the first transparent electrode layer 31 contains ZnO, and the specific resistance of ZnO is higher than the specific resistance of the second transparent electrode layer 33. Accordingly, current can easily pass through the first transparent electrode layer 31 formed of ZnO and having a predetermined pattern, thereby achieving easy current spreading.

In this modification, the second transparent electrode layer 33 has a larger or larger size air gap G than the third transparent electrode layer 35.

Fig. 5 (d) is a cross-sectional view showing another modification of the transparent electrode layer of the light emitting diode according to the third exemplary embodiment.

As shown in FIG. 5(d), in this modification of the third exemplary embodiment, the transparent electrode layer 30 includes a first transparent electrode layer 31, a second transparent electrode layer 33, and a third transparent electrode layer 35.

The third transparent electrode layer 35 is disposed on the second conductive type semiconductor layer 25 of the light emitting structure 20, and the first transparent electrode layer 31 is formed on the third transparent electrode layer 35 in a predetermined pattern. In this modification of the third embodiment, the first transparent electrode layer 31 is formed on some regions of the third transparent electrode layer 35 or the entire region of the third transparent electrode layer 35. The second transparent electrode layer 33 is formed on the third transparent electrode layer 35 to cover the first transparent electrode layer 31. corresponding The second transparent electrode layer 33 contacts a region of the third transparent electrode layer 35 in which the first transparent electrode layer 31 is not formed.

In this modification of the third exemplary embodiment, the second transparent electrode layer 33 is partially removed by etching to expose a portion of the first transparent electrode layer 31. In this configuration, the second electrode 43 may be formed on the exposed region of the first transparent electrode layer 31 and contact the exposed region of the first transparent electrode layer 31.

The pattern of the first transparent electrode layer 31 is the same as that of the first transparent electrode layer 31 according to the above-described third exemplary embodiment, and the second transparent electrode layer 33 and the third transparent electrode layer 35 are the same as those of the third exemplary embodiment. The other second transparent electrode layer 33 and the third transparent electrode layer 35 are the same. In addition, a tunnel junction layer (not shown) may be interposed between the third transparent electrode layer 35 and the light emitting structure 20.

FIG. 6 is a plan view of one example of the first transparent electrode layer 31 having a predetermined pattern in the third exemplary embodiment.

As described above, the pattern of the first transparent electrode layer 31 may have at least one shape selected from the group consisting of a circular shape, a hexagonal shape, a quadrangular shape, and a triangular shape, and may be formed along the second electrode 43 and the electrode extension portion 43a, as shown in the drawing. 6 is shown.

Referring to FIG. 6, the electrode extension portion 43a extends from the second electrode 43 to disperse the current accumulated at the second electrode 43. The second electrode 43 and the electrode extension portion 43a are formed on the second transparent electrode layer 33. With the structure in which the second electrode 43 and the electrode extension portion 43a are formed on the second transparent electrode layer 33, the first transparent electrode layer 31 may be formed in the same pattern as the second electrode 43 and the electrode extension portion 43a.

That is, the first transparent electrode layer 31 is in contact with the second electrode 43 and the electrode extension portion 43a. The same size and shape are formed, and are disposed under the second transparent electrode layer 33 along the second electrode 43 and the electrode extension 43a. Accordingly, the first transparent electrode layer 31 allows the current from the second electrode 43 and the electrode extension portion 43a to easily pass therethrough, thereby making it easier to spread the current in the horizontal direction.

While the invention has been described in connection with the embodiments the embodiments The scope of the technology of the present invention should be construed as covering all modifications or variations derived from the scope of the appended claims and the equivalents thereof.

10‧‧‧Base

20‧‧‧Lighting structure

21‧‧‧First Conductive Semiconductor Layer

23‧‧‧Active layer

25‧‧‧Second conductive semiconductor layer

30‧‧‧Transparent electrode layer

41‧‧‧First electrode

43‧‧‧second electrode

G‧‧‧ air gap

Claims (10)

A light emitting diode comprising: a light emitting structure comprising a first conductive type semiconductor layer, an active layer disposed on the first conductive type semiconductor layer, and a second conductive type semiconductor layer disposed on the active layer a first transparent electrode layer disposed on the light emitting structure to cover a portion of the light emitting structure and having a plurality of air gaps in the first transparent electrode layer; a second transparent electrode layer disposed at the On the first transparent electrode layer and having a plurality of air gaps formed in the second transparent electrode layer, the number or size ratio of the air gaps formed in the second transparent electrode layer is formed in the first a plurality of or a large number of the air gaps in a transparent electrode layer; and an electrode disposed on the second transparent electrode layer at a position corresponding to the first transparent electrode layer, wherein the first transparent The electrode layer has a specific resistance higher than that of the second transparent electrode layer. The light-emitting diode according to claim 1, wherein the first transparent electrode layer or the second transparent electrode layer comprises ZnO. The light emitting diode according to claim 1, further comprising: a tunnel junction layer formed between the light emitting structure and the first transparent electrode layer and containing NiO, Ga ₂ O ₃ and MgO At least one of them. The light-emitting diode according to claim 1, wherein the electrode portion is embedded in the second transparent electrode layer. The light emitting diode according to claim 1, further comprising: a third transparent electrode layer interposed between the first transparent electrode layer and the second transparent electrode layer and the light emitting structure, And has a plurality of air gaps. The light-emitting diode according to claim 5, wherein the first transparent electrode layer has a specific resistance higher than that of the third transparent electrode layer. The light emitting diode according to claim 1, wherein the first transparent electrode layer is formed on the light emitting structure in a predetermined pattern. The light-emitting diode according to claim 7, wherein the predetermined pattern of the first transparent electrode layer has at least one shape selected from the group consisting of a circle, a hexagon, a quadrangle, and a triangle. The light emitting diode according to claim 7, further comprising: an electrode extension extending from the electrode, wherein the pattern of the first transparent electrode layer corresponds to the electrode and the electrode The shape of the extension. The light emitting diode according to claim 1, wherein in each of the first transparent electrode layer and the second transparent electrode layer, the number or size of the air gap is from The light emitting structure gradually increases toward the electrode.