KR20150035149A - Nitride light emitting device - Google Patents

Abstract

The present invention discloses a nitride-based light-emitting device. The nitride-based light-emitting device of the present invention includes: a substrate; And a plurality of light emitting cells each including a buffer layer, a first conductivity type semiconductor layer, an active layer, a second semiconductor layer, and a transparent electrode layer on the substrate, wherein the plurality of light emitting cells include a plurality of light emitting cells Group, and the plurality of groups connected in series are connected in parallel with each other.
Here, the light emitting cells are in the form of a triangular prism, and one side of the light emitting cells is disposed to face the inclined surface of the adjacent light emitting cells, and the light emitting cells emit red, green, blue and ultraviolet rays.
The nitride-based light-emitting device according to the present invention realizes light-emitting cells having a plurality of triangular shapes on a single substrate, thereby reducing light loss due to total internal reflection.

Description

[0001] NITRIDE LIGHT EMITTING DEVICE [0002]

The present invention relates to a nitride-based light-emitting device.

The nitride-based light-emitting device is usually called a light-emitting diode (LED), and is a semiconductor light-emitting device that converts current into light. The wavelength of the light emitted by the light emitting diode is determined according to the semiconductor material used to manufacture the light emitting diode. This is because the wavelength of the emitted light is determined by the band gap of the semiconductor material, which represents the energy difference between the valence band electrons and the conduction band electrons.

In recent years, light emitting diodes have been increasingly used as light sources for displays, light sources for automobiles and light sources for lighting, and light emitting diodes that emit white light with high efficiency by using fluorescent materials or combining light emitting diodes of various colors Implementation is possible.

On the other hand, the brightness of the light emitting diode depends on various conditions such as the structure of the active layer, the light extraction structure capable of effectively extracting light to the outside, the size of the chip, and the type of molding member surrounding the light emitting diode.

1 is a view showing a structure of a nitride-based light emitting device according to the prior art.

1, the nitride-based light emitting device 10 includes a substrate 20, a buffer layer 12, a first conductivity type semiconductor layer 13, an active layer 14, a second conductivity type semiconductor layer 15, A transparent electrode layer 16, a second electrode 17, and a first electrode 18.

The buffer layer 12 may be formed to reduce the difference in lattice constant between the substrate 20 and the first conductive semiconductor layer 13 and may be formed of any one of GaN, AlN, AlGaN, InGaN, and AlInGaN, for example. .

In the active layer 14, holes (or electrons) injected through the first conductivity type semiconductor layer 13 and electrons (or holes) injected through the second conductivity type semiconductor layer 15, which are formed later, And is a layer that emits light due to a band gap difference of an energy band according to the material of the active layer 14. [

The conventional nitride-based light-emitting device has a generally rectangular shape, and thus the light generated in the active layer 14 is totally reflected within the light-emitting device. Therefore, light generated inside the light emitting device can not be easily extracted to the outside, resulting in optical loss.

Further, if the size of the light emitting device is increased to realize a high luminance characteristic, there is a problem that the current can not uniformly spread inside the light emitting device. (Current Spreading Degradation)

FIG. 2 is a view showing a light distribution of a nitride-based light-emitting device according to the prior art, FIG. 3 is a view showing current spreading characteristics of a nitride-based light-emitting device according to the prior art, Emitting device according to the present invention.

Referring to FIGS. 2 to 4, it can be seen that the light extraction efficiency is reduced due to the total internal reflection, and the light output is small. In addition, when looking at the region of the light to be emitted, it can be seen that the amount of light decreases remarkably toward the edge. Also, as shown in FIG. 3, the current spreading is good in the region where the electrode and the electrode are adjacent to each other with respect to the electrodes of the light emitting device (region A), but the current spreading decreases with distance from the electrodes B region). Particularly, when the size of the light emitting element is increased in order to realize a high output light emitting element, such current nonuniformity phenomenon becomes more prominent.

Referring to FIG. 4, the light efficiency (lm / W) of the conventional light emitting device is remarkably decreased as the forward current (If [mA]) supplied is larger.

As described above, the conventional light emitting device has a problem that the light loss is increased and the light efficiency is lowered due to a high probability of total internal reflection within the structure.

It is an object of the present invention to provide a nitride-based light emitting device that realizes light emitting cells having a plurality of triangular shapes on a single substrate, thereby reducing optical loss due to total internal reflection.

It is another object of the present invention to provide a nitride-based light emitting device in which a plurality of light emitting cells are formed on a single substrate, and the light emitting cells are connected in series and parallel structures to improve light efficiency.

According to an aspect of the present invention, there is provided a nitride-based light emitting device comprising: a substrate; And a plurality of light emitting cells each including a buffer layer, a first conductivity type semiconductor layer, an active layer, a second semiconductor layer, and a transparent electrode layer on the substrate, wherein the plurality of light emitting cells include a plurality of light emitting cells Group, and the plurality of groups connected in series are connected in parallel with each other.

Here, the light emitting cells are in the form of a triangular prism, and one side of the light emitting cells is disposed to face the inclined surface of the adjacent light emitting cells, and the light emitting cells emit red, green, blue and ultraviolet rays.

In addition, the plurality of light emitting cells are connected in series or parallel structure by connection portions, and the connection portions and the light emitting cells are interposed with an insulating film pattern for preventing electrical short.

The nitride-based light-emitting device according to the present invention realizes light-emitting cells having a plurality of triangular shapes on a single substrate, thereby reducing light loss due to total internal reflection.

The nitride-based light-emitting device according to the present invention has a plurality of light-emitting cells formed on a single substrate, and the light-emitting cells are connected in series and parallel structures to improve light efficiency.

1 is a view showing a structure of a nitride-based light emitting device according to the prior art.
2 is a view showing a light distribution of a nitride-based light emitting device according to the related art.
FIG. 3 is a graph showing current spreading characteristics of a nitride-based light emitting device according to the prior art.
4 is a graph showing light efficiency characteristics of a nitride-based light emitting device according to the related art.
5 is a view illustrating a structure of a light emitting diode package including a light emitting device according to the present invention.
6 is a cross-sectional view taken along the line I-I 'of FIG.
7A is a view illustrating a structure of a light emitting device according to a first embodiment of the present invention.
FIG. 7B is a view showing an equivalent circuit for the light emitting device of FIG. 7A.
8A is a view illustrating the structure of a light emitting device according to the first embodiment of the present invention.
FIG. 8B is a view showing an equivalent circuit for the light emitting device of FIG. 8A.
9A and 9B are cross-sectional views taken along line II-II 'and III-III' of FIG. 7A.
10 is a graph showing current spreading characteristics of the light emitting device according to the first embodiment of the present invention.
11 is a view showing the light distribution of the nitride-based light-emitting device according to the present invention.
FIG. 12 is a diagram comparing light efficiency characteristics of a conventional nitride-based light-emitting device and a nitride-based light-emitting device of the present invention.
13 is a graph comparing light efficiency characteristics according to the size of the nitride light emitting device of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

The light emitting device according to the present invention is mounted on a package, and can be used as a light source of a flat display device or as an illumination.

FIG. 5 is a view illustrating a structure of a light emitting diode package including a light emitting device according to the present invention, and FIG. 6 is a sectional view taken along the line I-I 'of FIG.

5 and 6, the light emitting diode package 100 includes a package body 120 having a well structure, a first light emitting device 50 and a second light emitting device 50 mounted in the package body 120, 60 and a mold layer 200 and a phosphor layer 300 stacked to cover the first and second light emitting devices 50 and 60 in a well region of the package body 120. On both sides of the package body 120, a first lead frame 150a and a second lead frame 150b for electrical connection with external signal patterns are formed.

The method of mounting the first and second light emitting devices 50 and 60 includes a wire bonding method of connecting an anode and a cathode of a light emitting device to signal patterns using wires, There is a flip chip bonding method that connects with signal patterns.

A base substrate 122 is disposed under the package body 120 so that the first light emitting device 50 and the second light emitting device 60 are mounted.

A predetermined inclined surface 250 is formed on the inner periphery of the package body 120 and a protrusion 260 is formed on the inclined surface 250 for separating the mold layer 200 and the phosphor layer 300 .

As described above, when the mold layer 200 and the phosphor layer 300 are separately formed, each of the layers can be formed in a uniform thickness.

In particular, the first and second light emitting devices 50 and 60 are formed of a plurality of light emitting cells in a triangular shape on a single substrate. The specific structure of the light emitting device related to this is described in Figs. 7A and 8A.

FIG. 7A is a view illustrating a structure of a light emitting device according to a first embodiment of the present invention, and FIG. 7B is a diagram illustrating an equivalent circuit for the light emitting device of FIG. 7A.

7A and 7B, the light emitting device according to the first embodiment of the present invention forms a plurality of light emitting cells C1, C2, C3, and C4 having a triangular shape on a single substrate S .

As shown in the figure, the first to fourth light emitting cells C1, C2, C3, and C4 are formed on a substrate S, The light emitting device includes a buffer layer, a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, and a transparent electrode layer. Details related to this will be described with reference to FIG.

In addition, depending on the characteristics of the active layer, each of the light emitting cells may emit light of any one of red, green, blue, and ultraviolet. Thus, each light emitting cell can emit different lights.

In the first embodiment of the present invention, the light emitting device is implemented by serial and parallel combination of the first to fourth light emitting cells C1, C2, C3, and C4 on the substrate S.

As shown in the drawing, the first light emitting cell (C1 = D1) and the second light emitting cell (C2 = D2) form a first group connected in series with each other by a fourth connecting portion 214, (C3 = D3) and the fourth light emitting cell (C4 = D4) form a second group connected in series with each other by the second connection portion 212. [

Then, the anode of the first light emitting cell (C1 = D1), the anode of the third light emitting cell (C3 = D3), the cathode of the second light emitting cell (C2 = D2) The cathodes are respectively connected by a third connecting portion 213 and a first connecting portion 211 so that the first and second light emitting cells C1 and C2 connected in series and the third connecting portion 211 of the second group, The four light emitting cells C3 and C4 are connected in parallel with each other. Particularly, a P pad 210 and an N pad 220 are formed in the third connection part 213 and the first connection part 211 for the parallel connection.

In addition, the plurality of light emitting cells C1 to C4 formed in the light emitting device of the present invention are each formed into a triangular shape (triangular column) to reduce light loss due to total internal total reflection of light.

In addition, a plurality of light emitting cells C1 to C4 are connected in series and parallel structures on one substrate S, thereby improving current spreading characteristics. This is because the light emitting cells formed in the triangular structure are arranged such that the respective inclined surfaces face the adjacent light emitting cells and current flows through the inclined surfaces of the triangles.

FIG. 8A is a view illustrating a structure of a light emitting device according to a first embodiment of the present invention, and FIG. 8B is a diagram illustrating an equivalent circuit for the light emitting device of FIG. 8A.

8A and 8B, the light emitting device according to the second embodiment of the present invention is realized by forming a plurality of light emitting cells (C1 to C6) having a triangular shape on a single substrate (S).

As shown in the figure, the first to sixth light emitting cells C1, C2, C3, C4, C5, and C6 are formed on a substrate S, , And has a triangular shape.

 In the second embodiment of the present invention, the first through sixth light emitting cells C1, C2, C3, C4, C5, and C6 are implemented in series and in parallel on the substrate S of the light emitting device.

As shown in the drawing, the first light emitting cell (C1 = D1) and the second light emitting cell (C2 = D2) are connected in series to each other by a sixth connecting portion 316, The third light emitting cell (C3 = D3) is connected in series to the first connection part 311 to form a first group.

The fourth light emitting cell C4 = D4 and the fifth light emitting cell C5 = D5 are connected to each other in series by the fourth connecting portion 314 and the fifth light emitting cell C5 = D5 and the sixth light emitting cell C5 = C6 = D6 are connected in series by the third connection part 313 to form the second group.

The anode of the first light emitting cell C1 = D1, the anode of the fourth light emitting cell C4 = D4, the cathode of the third light emitting cell C3 = D3, and the cathode of the sixth light emitting cell C6 = The cathodes are connected by the fifth connection part 315 and the second connection part 312 respectively and are connected to the first to third light emitting cells C1, C2, C3 of the first group and the fourth To sixth light emitting cells C4, C5, and C6 are connected in parallel with each other. Particularly, a P pad 310 and an N pad 320 having a large area are formed in the fifth connection part 315 and the second connection part 312 for parallel connection.

In addition, the plurality of light emitting cells (C1 to C6) formed in the light emitting device of the present invention are each formed into a triangular shape (triangular column) to reduce light loss due to total internal total reflection of light.

In addition, a plurality of light emitting cells (C1 to C6) are connected in series and parallel structures on one substrate (S), thereby improving current spreading characteristics.

9A and 9B are cross-sectional views taken along line II-II 'and III-III' of FIG. 7A.

9A and 9B, the light emitting device of the present invention includes first to second light emitting cells C1 to C4 having a triangular shape on a substrate (S) 400, The first conductive semiconductor layers 402, 502, and 602, the active layers 403, 503, and 603, the second conductive semiconductor layers 404, 504, and 604, (405, 505, 605).

The first conductive semiconductor layers 402, 502 and 602, the active layers 403, 503 and 603, the second conductive semiconductor layers 404, 504 and 604 and the transparent electrode layer 405, 505 and 605 are formed on the substrate 400 by a method such as chemical vapor deposition (CVD), molecular beam epitaxy (MBE), sputtering, or vapor phase epitaxy (HVPE) And the present invention is not limited thereto.

At least one of sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP and Ge can be used as the substrate 400.

The buffer layers 401, 501, and 601 may be formed to reduce the difference in lattice constant between the substrate 400 and the first conductive semiconductor layers 402, 502, and 602.

The material of the buffer layers 401, 501, and 601 may include aluminum (Al), for example, Al _x Ga ₁ -xN (0.5 _{? X? 1} ). The material of the buffer layers 401, 501, and 601 may include aluminum (Al) in a ratio equal to or higher than gallium (Ga) . However, the materials of the buffer layers 401, 501, and 601 are not limited.

The first conductive semiconductor layers 402, 502, and 602 may be formed of, for example, an n-type semiconductor layer, and the material thereof may be Al _x Ga ₁ -xN (0.02 _{? X} ? 0.08). The first conductive semiconductor layer 130 may be doped with an n-type dopant such as Si, Ge or Sn. X has a value in the range of 0.02 to 0.08, preferably about 0.05. However, the materials of the first conductivity type semiconductor layers 402, 502, and 602 are not limited.

The active layers 403, 503, and 603 may be formed of a single quantum well structure or a multi quantum well structure (MQW). In an exemplary embodiment, the active layers 403, 503, But the present invention is not limited thereto.

The active layers 403, 503, and 603 may include a plurality of barrier layers and a plurality of quantum well layers formed between the plurality of barrier layers. The active layer 403, 503, and 603 are not limited to the laminated structure of the active layer 140.

The second conductive semiconductor layer (404, 504, 604) may be, for example, formed in a p-type semiconductor layer, the material is Al _x Ga _{1 -} may be the _x N (0.1≤x≤0.3). The second conductive semiconductor layers 404, 504, and 604 are doped with a p-type dopant such as Mg or Ba. X has a value in the range of 0.1 to 0.3, preferably about 0.2. However, the materials of the second conductivity type semiconductor layers 404, 504, and 604 are not limited.

Meanwhile, the second conductive semiconductor layers 404, 504, and 604 may be formed by stacking a plurality of layers.

On the second conductive semiconductor layer 150, transparent electrode layers 405, 505, and 605 may be formed. The transparent electrode layers 405, 505 and 605 may be formed of ITO, IZO (In-ZnO), GZO (Ga-ZnO), AZO (Al-ZnO), AGZO And at least one of IrO _x , RuO _x , RuO _x / ITO, Ni / IrO _x / Au, and Ni / IrO _x / Au / ITO.

That is, when the buffer layer, the first conductivity type semiconductor layer, the active layer, the second conductivity type semiconductor layer, and the transparent electrode layers are sequentially formed on the substrate 400, as shown in FIGS. 7A, 9A, and 9B Similarly, the etching process is performed to pattern the first to fourth light emitting cells C1 to C4 in a triangular shape. At this time, the first conductivity type semiconductor layers of the cathode regions of the first to fourth light emitting cells C1 to C4 connected to the first to fourth connection portions 211, 212, 213, do.

The first conductive semiconductor layers 402, 502 and 602, the active layers 403, 503, and 603, and the second conductive semiconductor layers 402 and 503, which correspond to the light emitting cells, Semiconductor layers 404, 504, and 604 and transparent electrode layers 405, 505, and 605 are formed.

Then, as shown in the drawing, after an insulating film is formed on the substrate 400, first to fourth connection portions 211, 212, 213, and 214 corresponding to the first to fourth light emitting portions An insulating film pattern 410 is formed on one side of the cells C1 to C4.

As described above, when the insulating film pattern 410 is formed, a metal film is formed on the substrate 400 and is etched to form the first to fourth connection portions 211, 212, 213, and 214 shown in FIG. 7A do.

9A and 9B, the first and second light emitting cells C1 and C2 are connected to the first conductive semiconductor layer 502 of the first light emitting cell C1 by the fourth connecting portion 214, And the transparent electrode layer 405 of the second light emitting cell C2 is electrically connected. Accordingly, the first and second light emitting cells C1 and C2 are connected in series by the fourth connection unit 214. [

The second and fourth light emitting cells C2 and C4 are connected to the first conductive semiconductor layers 402 and 602 of the second and third light emitting cells C2 and C4 by the first connection part 211, And are electrically connected to each other. Accordingly, the second and fourth light emitting cells C2 and C4 are connected in parallel.

When the first to fourth light emitting cells C1, C2, C3 and C4 and the first to fourth connecting parts 211, 212, 213 and 214 are formed on the substrate 400 as described above, A protective film 415 is formed on the entire surface to protect the light emitting cells of the light emitting device from the outside.

10 is a view showing a current spreading characteristic of the light emitting device according to the first embodiment of the present invention, and FIG. 11 is a view showing a light distribution of the nitride based light emitting device according to the present invention.

As shown in FIGS. 10 and 11, the first and second light emitting cells C1, C2, C3, and C4 having a triangular shape are formed on a substrate, and they are connected in series and parallel hybrid connection structures .

The current flows to the adjacent second light emitting cells C2 through the inclined surfaces of the first light emitting cells C1 by the series connection of the first and second light emitting cells C1 and C2, (C3, C4) also flow in the same form. Accordingly, in the conventional light emitting device, a current flows intensively in the center portion where the electrodes are formed. In the light emitting device of the present invention, current flows uniformly in the entire region of the light emitting device due to the connection structure of the plurality of light emitting cells. Therefore, the light emitting device having a plurality of light emitting cells of the present invention improves the current spreading characteristic as compared with the prior art.

Comparing FIG. 2 and FIG. 11, it can be seen that the light emitting device of the present invention has remarkably improved light extraction efficiency as compared with the conventional light emitting device.

FIG. 12 is a graph comparing light efficiency characteristics of a conventional nitride-based light-emitting device and a nitride-based light-emitting device of the present invention, and FIG. 13 is a graph comparing light efficiency characteristics of the nitride light-emitting device of the present invention.

12 and 13, both the conventional nitride-based light-emitting device and the nitride-based light-emitting device of the present invention exhibit low light efficiency at high power (current), but the nitride-based light-emitting device of the present invention has a higher Light efficiency characteristics can be seen.

13, Case 1 is a light emitting element having a size of 40 * 30 [mil], Case 2 is a case of having two light emitting elements having a size of 40 * 30 [mil] As a result, it can be seen that the light efficiency of Case 2 composed of two light emitting devices is excellent.

However, as in the case 3, when the light emitting device is a single device and the size is increased to 40 * 60 [mil], the light emitting device having the same light efficiency as the two light emitting devices of size 40 * 30 [mil] can see.

Therefore, when the light emitting device composed of a plurality of light emitting cells is used as in the present invention, the two light emitting devices mounted in the light emitting diode package can be reduced to one light emitting device, thereby reducing manufacturing cost. In addition, when the light emitting device of the present invention is applied to a region where a plurality of light emitting devices are mounted, various design margins can be secured.

100: light emitting diode package 120: package body
50: first light emitting element 60: second light emitting element
200: mold layer 300: phosphor layer
401, 501, and 601: buffer layers 402, 502, and 602:
403, 503, 603: active layer 404, 504, 604: second conductivity type semiconductor layer
405, 505, 605: transparent electrode layer
C1, C2, C3, and C4: first, second, third, and fourth light emitting cells

Claims (6)

Board; And
A plurality of light emitting cells each including a buffer layer, a first conductivity type semiconductor layer, an active layer, a second semiconductor layer, and a transparent electrode layer on the substrate,
Wherein the plurality of light emitting cells include a plurality of groups in which the light emitting cells are connected in series, and the plurality of groups connected in series are connected in parallel with each other.
The nitride-based light emitting device according to claim 1, wherein the light emitting cells have a triangular prism shape.
The nitride-based light emitting device according to claim 2, wherein one side of the light emitting cell is disposed to face the inclined surface of the adjacent light emitting cell.
The nitride-based light emitting device according to claim 1, wherein the light emitting cells emit light of any one of red, green, blue, and ultraviolet.
The nitride-based light emitting device of claim 1, wherein the plurality of light emitting cells are connected in series or parallel structure by connecting portions.
6. The nitride-based light emitting device according to claim 5, wherein the connection portions and each of the light emitting cells have an insulating film pattern interposed therebetween in order to prevent an electrical short.

Images