KR101435511B1 - Light emitting diode with labrynth - Google Patents

Abstract

The present invention relates to a light emitting diode which can improve luminous efficiency by enhancing uniformity of current distribution between an n type electrode and a p type electrode thereof, and reducing an internal reflection and reabsorption phenomenon thereof. To achieve this, the present invention provides the light emitting diode with a maze shape including a base substrate; a main substrate layer (35) disposed on an upper part of the base substrate (310) to form a p-n hetero-junction structure of a semiconductor having a p type electrode pad (360) and an n type electrode pad (350) connected to an external power source; a transparent electrode (370) forming an upper part of the main substrate layer (35); and a first pattern part (300) engraved to have a maze shape by an upper part of the transparent electrode (370) which is between an n type electrode finger (352) extending from the n type electrode pad (350) and a p type electrode finger (362) extending from the p type electrode pad (360).

Description

[0001] LIGHT EMITTING DIODE WITH LABRYNTH [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode, and more particularly, to a light emitting diode having a labyrinth shape, which is configured to form an etched structure of a labyrinthine pattern to improve luminous efficiency.

2. Description of the Related Art LIGHT EMITTING DIODE is a semiconductor device which is generated based on the recombination of electrons and holes, and is widely used as a light source for a variety of devices such as optical communication, electronic devices, mobile phones, camera flashes, and LCD backlights.

For example, lighting devices using light emitting diodes are in the spotlight as next generation lighting for replacing them in the future because they have lower power consumption and lower heat generation than conventional incandescent lamps and fluorescent lamps.

As such a light emitting diode, a light emitting diode having a p-n junction structure of a unidirectional vertical structure is widely used.

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

1, the light emitting diode 10 includes an n-GaN layer 120 forming an n-type semiconductor layer and a p-GaN layer 130 forming a p-type semiconductor layer on a base substrate 110 formed below And an active layer 140 (QUANTUM WELL ACTIVE LAYER) disposed therebetween.

The n-GaN layer 120 and the p-GaN layer 130 each include an n-type electrode 150 electrically connected to an external power source and a p-type electrode 160, respectively.

The current flows from the p-GaN layer 130 through the active layer 140 to the n-GaN layer 120 through the light emitting diode 10. Therefore, when a positive load is applied to the p-type electrode 160 of the light emitting diode 10 and a negative load is applied to the n-type electrode 150, the p-type GaN layer 130 and the n- Holes and electrons are collected and recombined in the active layer 140 to emit light.

Since the general light emitting diode 10 has a limitation that the optical extraction efficiency is determined from the beginning due to the internal quantum efficiency of the active layer 140 and the limitation of the structural characteristics, (MULTIPLE QUNTUM-WELL) structure is formed in the active layer to solve the problem of limiting the electro-optical conversion efficiency and the light emission efficiency of the light emitting diode (10).

On the other hand, in the upper part of the p-GaN layer 130, the light emitted from the light emitting structure is likely to be reflected to the inside of the light emitting structure at the upper part of the p-GaN layer 130 or to be totally reflected to the side.

Therefore, in order to reduce the refractive index difference with the external environment (air, etc.), ITO (INDIUM TIN OXIDE), IZO (INDIUM ZINC OXIDE), ZnO (ZINC OXIDE ) Or ZCO (ZINC CARBON OXIDE) or the like.

Since the transparent electrode 170 not only reduces the total reflection but also has good transparency, it is possible to increase the extraction efficiency of light emitted toward the p-GaN layer 130.

However, since the conductivity of the transparent electrode 170 is not high, current is not diffused well and the current injection area is small. Such a small current injection area lowers the luminous efficiency of the light emitting diode 10 It is known as the main reason.

On the other hand, it is known that the distance between the two electrodes of the light emitting diode 10 greatly nourishes the current distribution.

2 is a computer simulation image of a current distribution diagram of the light emitting diode according to the distance d between the n-type electrode and the p-type electrode.

As shown in FIG. 2, in the light emitting diode structure, most of the current flows in the MESA EDGE region. Such a non-uniform current distribution is known to cause a decrease in the efficiency of the light emitting diode. It can be seen that a more uniform current distribution is obtained.

As an example of a conventional technique for preventing the efficiency deterioration of the light emitting diode described above, Korean Patent Laid-Open No. 10-2012-0111960 discloses a light emitting diode in which a p-type electrode and an n-type electrode are formed on both sides, A technique for improving the uniformity of the current distribution is described.

Japanese Laid-Open Patent Application No. 10-2003-0018029 discloses a technique for improving uniformity of current distribution by arranging a plurality of p-type electrode fingers and a plurality of n-type electrode fingers close to each other.

However, in Korean Patent Laid-Open No. 10-2012-0111960, the light emitting area of the transparent electrode is reduced due to the formation of the opening, thereby lowering the luminous efficiency of the light emitting diode. Korean Patent Laid-Open No. 10-2003-0018029 Light generated in the active layer is lost by a plurality of electrode fingers, thereby increasing the efficiency of the light emitting diode.

Korean Patent Laid-Open No. 10-2012-0111960 Korean Patent Laid-Open No. 10-2003-0018029

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to improve uniformity of current distribution between an n-type electrode and a p-type electrode of a light emitting diode and to reduce internal reflection and re- And it is an object of the present invention to provide a light emitting diode having a labyrinth shape capable of further improving the luminous efficiency (LUMINOUS EFFICIENCY).

According to an aspect of the present invention, there is provided a semiconductor device including: a base substrate; a p-type electrode pad formed on the base substrate to form a pn junction structure of a semiconductor and connected to an external power source; A transparent electrode formed on the main substrate layer, and an n-type electrode finger extending from the n-type electrode pad and a p-type electrode finger extending from the p- And a first pattern portion that is etched to have a labyrinth shape by a line type.

And the p-type electrode finger extends horizontally to both sides of the n-type electrode pad.

The main substrate layer may include a p-type substrate layer to which the p-type electrode pad is connected, an n-type substrate layer to which the n-type electrode pad is connected, and an active layer disposed between the p-type substrate layer and the n-type substrate layer.

And the p-type substrate layer and the n-type substrate layer are GaN.

The first pattern portion may be etched to a depth from the transparent substrate to the n-type substrate layer.

The first pattern unit may include a plurality of first unit pattern structures that divide the n-electrode fingers and the p-electrode fingers in a plurality of directions.

The p-type electrode fingers are horizontally arranged on both sides of the n-type electrode fingers, and the first unit pattern structures are arranged in parallel to both sides of the n-type electrode fingers.

The first unit pattern structure may be formed in a number that divides the extending direction of the n-type electrode finger and the p-type electrode finger into eight equal parts.

The first unit pattern structure includes a first line pattern extending a predetermined distance from a central end of the center of the p-type electrode finger and the n-type electrode finger, and a second line pattern extending from the first line pattern, Extending from the opposite end of the first line pattern to extend through the extended end of the first line pattern and then being bent at both sides toward the p-type electrode finger and the n-type electrode finger, respectively, A second line pattern extending a predetermined distance from the first line pattern, and a second line pattern extending from the opposite end extending from the second line pattern while being in contact with the p-type electrode finger and the n-type electrode finger, And a third line pattern extending from the first line pattern to the second line pattern and extending by a predetermined distance.

The path of the labyrinth formed by the first line pattern, the second line pattern, and the third line pattern has a constant width.

According to another aspect of the present invention, there is provided a semiconductor device comprising: a base substrate; a p-type electrode pad formed on the base substrate to form a pn junction structure of a semiconductor and connected to an external power source; Type electrode fingers extending from the p-type electrode pads horizontally with respect to the n-type electrode fingers; and a p-type electrode fingers extending from the p- At least one n-type subfinger extending perpendicularly to the p-type electrode finger from a position spaced apart from the n-type electrode finger by a predetermined distance, and the p-type electrode finger and the n-type electrode finger And a second pattern portion that is etched so as to have a labyrinth shape by a line type which is bent in a large number of turns while having a smaller turning radius at an upper portion of the transparent electrode between the electrode fingers Emitting diode is provided.

The second pattern unit may include a plurality of second unit pattern structures that partition a plurality of the n-type electrode fingers and the p-type electrode fingers in a direction in which the n-type electrode fingers extend.

The n-type sub finger has an extended end portion spaced apart from the p-type electrode finger, and the second unit pattern structure is bent from the end portion of the extended n-type sub finger to form a gap between the p-type electrode finger and the n- A fourth line pattern formed by folding a plurality of lines into a space of the first line pattern.

And the passage of the maze formed by the fourth line pattern is characterized in that a constant width is continuous.

According to the light emitting diode of the present invention, it is possible to achieve a uniform current distribution due to the electric field distribution effect at the periphery of the electrode and to reduce the quantum well distortion caused by the reduction of the STRAIN INDUCED PIEZOELECTRIC FIELD, thereby improving the luminous efficiency of the high output light emitting diode have.

Further, according to the light emitting diode of the present invention, the surface area of the light emitting region contacting with the air layer is increased by the formation of the labyrinthine pattern, the internal reflection and reabsorption phenomenon of the photon generated in the light emitting diode is reduced, The light extraction efficiency of the diode can be improved.

1 is a sectional view showing the structure of a general light emitting diode.
2 is a graph showing a current distribution according to a distance between electrodes of a light emitting diode.
3 is a cross-sectional view illustrating a structure of a light emitting diode according to an embodiment of the present invention.
4 is a plan view showing an upper shape of the light emitting diode shown in FIG.
5 is a sectional view showing the first pattern portion shown in Figs. 3 and 4. Fig.
FIG. 6 is a graph showing the loss area and the FORWARD VOLTAGE of the active layer according to the distance between the electrodes of the light emitting diode according to an embodiment of the present invention.
7 is a cross-sectional view illustrating a structure of a light emitting diode according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which illustrate exemplary embodiments of the present invention. The present invention is not limited to these embodiments.

3 shows an overall structure of a light emitting diode 30 according to an embodiment of the present invention.

Referring to FIG. 3, a light emitting diode 30 according to the present embodiment includes a main substrate layer 35 formed on a base substrate 310 formed below.

The main substrate layer 35 includes an n-type substrate layer 320, an active layer 340 formed on the n-type substrate layer 320, a p-type substrate layer 330 formed on the active layer 340, Lt; / RTI >

The n-type substrate layer 320, the active layer 340 and the p-type substrate layer 330 constituting the main substrate layer 35 are formed of a gallium nitride (GaN) compound semiconductor material, i.e., (Al, In, Ga) N And the compositional element and the composition ratio are determined so that the active layer 340 emits light of a desired wavelength, for example, ultraviolet light or visible light.

The base substrate 310 may be a growth substrate for growing a gallium nitride (GaN) based compound semiconductor layer, such as a sapphire substrate, a potassium nitride substrate, a silicon carbide substrate, or a silicon substrate.

2, the p-type substrate layer 330 and the n-type substrate layer 320 are stacked on top of the light emitting diode 30 and the n-type substrate layer 320 Are stacked on the lower portion, but may be configured in the opposite manner.

In addition, the p-type substrate layer 330 and the n-type substrate layer 320 may be formed as a single layer, but may be formed in a multi-layer structure. When the base substrate 310 is a growth substrate, A buffer layer (not shown) such as GaN or AlN may be formed between the base substrate 310 and the n-type substrate layer 320.

An n-type electrode pad 350 connected to the n-type substrate layer 320 and a p-type electrode pad 360 connected to the p-type substrate layer 330 are formed on the p-type substrate layer 330, A transparent electrode 370 is disposed between the p-type electrode pads 360.

Fig. 4 shows a planar shape of the light emitting diode 30 shown in Fig.

4, the n-type electrode pad 350 and the p-type electrode pad 360 are electrically connected to the n-type substrate layer 320 and the p-type substrate layer 330, respectively, As shown in FIG.

In this embodiment, the structure of the light emitting diode 30 having a size of about 600 mu m to about 1200 mu m is shown, and an n-type electrode finger (not shown) extending at least one from the n-type electrode pad 350 and the p- A p-type electrode finger 352 and a p-type electrode finger 362 are formed.

That is, the n-type electrode pad 350 forms an n-type electrode finger 352 extending to the center of the light emitting diode 30 and the p-type electrode pad 360 extends along the outer side of the light emitting diode 30 and a p-type electrode finger 362 which is positioned in parallel with the n-type electrode finger 352 is formed.

In this case, the p-type electrode finger 362 is formed in two and horizontally positioned on both sides of one n-type electrode finger 352 extending to the center of the light emitting diode 30, Alternatively, a plurality of n-type electrode fingers 352 and p-type electrode fingers 362 may be formed at the same time, and a plurality of the n-type electrode fingers 352 and the p-type electrode fingers 362 may be arranged horizontally.

The active layer 340, the p-type substrate layer 330 and the transparent electrode 370 stacked on the n-type substrate layer 320 are formed on both sides of the n-type electrode pad 350 and the n-type electrode finger 352 And the n-type electrode pad 350 and the n-type electrode finger 352 are exposed to the upper side.

Thus, the main substrate layer 35 formed on the n-type substrate layer 320 can be divided into two regions based on the n-type electrode finger 352 extending from the n-type electrode pad 350.

According to the present embodiment, between the n-type electrode finger 352 and the p-type electrode finger 362 on the transparent electrode 370 disposed between the p-type substrate layer 330 and the p- The first pattern unit 300 is formed to have a labyrinth shape by a line type on the unit area of the light emitting diode 30 to help disperse the current in the light emitting diode 30.

The first pattern unit 300 may be formed on both sides of the main substrate layer 35 divided on the basis of the n-type electrode finger 352.

The first pattern unit 300 may include an n-type substrate layer 320 formed between the transparent electrode 370 and the p-type electrode pad 360 formed on the transparent electrode or formed under the transparent electrode 370, As shown in FIG.

5 shows an embodiment of the first pattern unit 300 according to the present invention.

5, the first pattern unit 300 is formed on the upper portion of the transparent electrode 370 in a unit area portion formed by a distance between the n-type electrode finger 352 and the p-type electrode finger 362, And then performing an etching process so as to form a maze shape.

In particular, the first pattern unit 300 includes a plurality of first unit pattern structures 500 in which a plurality of n-type electrode fingers 352 and a plurality of p-type electrode fingers 362 are extended, .

5, the first unit pattern structure 500 includes a first line pattern 510a, a second line pattern 510b, and a third line pattern 510c, To form a labyrinth passageway structure.

The first line pattern 510a is extended a predetermined distance from one end of the center of the first unit pattern structure 500 that is horizontal to the P type electrode finger 362 and the n type electrode finger 352, A second line pattern 510b and a third line pattern 510b are formed on the outer side of the first line pattern 510a.

At this time, the first line pattern 510a has an extension length that does not touch the opposite end of the first unit pattern structure 500 positioned in the extending direction but is spaced apart.

The second line pattern 510b is horizontally formed on both sides of the first line pattern 510a.

In particular, the second line pattern 510b extends from the opposite end of the first line pattern 510a in the first unit pattern structure 500 to extend beyond the extended end of the first line pattern 510a. And has an extension length spaced apart from the opposite end of the first unit pattern structure 500.

The extended end of the second line pattern 510b is bent in a direction opposite to the first line pattern 510a and extends a certain distance.

The third line pattern 510c is formed on the first unit pattern structure 500 in such a manner that the third line pattern 510c extends from the first unit pattern structure 500 to the second unit pattern structure 500 while being in contact with the p- Extends from the opposite end of the line pattern 510b and extends beyond the bent portion of the second line pattern 510b and is bent and extended by a certain distance toward the second line pattern 510b.

The end portion extending a certain distance toward the second line pattern 510b extends a certain distance again in a direction extending in contact with the p-type electrode finger 362 and the n-type electrode finger 352. [

The first line pattern 510a, the second line pattern 510b, and the third line pattern 510c constituting the first unit pattern structure 500 may be formed of a metal pattern.

FIG. 6 shows a simulation result of the loss area of the active layer and the FORWARD VOLTAGE according to the interelectrode distance d of the light emitting diode 30 according to the embodiment of the present invention.

The size of the first unit pattern structure 500 according to the present simulation is 150 μm × 300 μm and the structure of the first unit pattern structure 500 is 2 × 8, The size of the light emitting diode 30 having a size of 1200 mu m is considered.

Here, the widths of the first to fourth line patterns are 4 mu m and the etching depth of the pattern is 1.8 mu m.

In FIG. 6, the horizontal axis represents the distance between the electrodes of the light emitting diode 30, and the vertical axis represents the FORWARD VOLTAGE and the loss area of the active layer, respectively. As a result, it can be seen that as the distance d between the electrodes decreases, the loss area of the active layer increases to 4% DPTJ 18%, while the FORWARD VORTAGE decreases to about 0.1V.

Accordingly, the light emitting diode 30 according to the present invention decreases the overall active layer area, but mainly increases the area of the effective active layer area through which the current flows, thereby increasing the current injection efficiency. Finally, the efficiency of the light emitting diode 30 Degradation can be improved.

In addition, according to the present invention, it is possible to design an optimum structure for compensating the active layer area loss due to the formation of a line pattern of the light emitting diode 30.

The first unit pattern structure 500 may be formed by optimally combining the lengths and shapes of the first line pattern 510a, the second line pattern 510b and the third line pattern 510c, Can be configured to have a constant width.

5, the length of the first unit pattern structure 500 with respect to the extending direction of the p-type electrode finger 362 and the n-type electrode finger 352 is set to 4a (4 x a) Assuming that the length of the first unit pattern structure 500 with respect to the direction in which the electrode finger 362 and the n-type electrode finger 352 face is 6b (6 × b), assuming that a and b have the same length do.

First, the first line pattern 510a extends from one end of the first unit pattern structure 500 to a length of 3a.

The second line pattern 510b extends from the opposite direction of the first line pattern 510a by a length of 3a and extends from the extended end portion to the n-type electrode fingers 352 and the p-type electrode fingers 362 The path width of the labyrinth path formed by the first line pattern 510a and the second line pattern 510b is maintained to be the same.

The third line pattern 510c is in contact with the p-type electrode finger 362 and the n-type electrode finger 352 so as to extend in the direction opposite to the direction in which the second line pattern 510b extends, The first line pattern 510a is extended toward the second line pattern 510b by b and then extended again by a in the extending direction in contact with the p-type electrode finger 362 and the n-type electrode finger 352, And the width of the labyrinth passages formed by the second line pattern 510b and the third line pattern 510c may all be the same.

Therefore, it is possible to compensate for the area loss of the active layer 340 by forming a constant channel width of the first unit pattern structure 500, thereby enhancing the uniform current distribution effect by the electric field distribution effect.

7 shows a configuration according to another embodiment of the present invention.

The light emitting diode 30 according to the present embodiment includes a p-type electrode finger 362 extending from the p-type electrode pad 360 to both sides of the n-type electrode finger 352 extending from the n-type electrode pad 350 Are the same as those of the previous embodiment, and the same reference numerals as those of the preceding embodiments are denoted by the same reference numerals in the drawings used in the description of this embodiment.

The difference in the present embodiment further includes a plurality of n-type sub-fingers 752 extending vertically toward the p-type electrode finger 362 on both sides of a predetermined spacing of the n-type electrode fingers 352, the second pattern portion 700 is formed in the inner space formed by the n-type electrode finger 352 and the p-type electrode finger 362 at the same time as the spaced apart space of the n-type sub finger 752.

7, the second pattern unit 700 includes a p-type electrode finger 362 and an n-type electrode finger (not shown) partitioned by an n-type sub finger 752 at an upper portion of the transparent electrode 370 352 are formed in the shape of a labyrinth by being bent and extending a plurality of times with a smaller turning radius.

In particular, the second pattern unit 700 includes a plurality of second unit pattern structures (not shown) divided by the n-type sub fingers 752 in the direction in which the p-type electrode finger 362 and the n-type electrode finger 352 extend 701 may be continuously arranged.

At this time, the end of the n-type sub finger 752 extending toward the p-type electrode finger 362 is spaced apart from the p-type electrode finger 362 by a predetermined distance, and the second unit pattern structure 701 is extended and a fourth line pattern 710 that is bent from the end of the n-type sub finger 752 and folded into a space between the p-type electrode finger 362 and the n-type electrode finger 352.

Referring to the enlarged view of FIG. 7, the second unit pattern structure 701 may be formed by optimally combining the lengths and shapes of the fourth line patterns 710 so that the paths of the formed labyrinths are formed to have a constant width Configurable.

That is, assuming that the distance between the extended end of the n-type sub finger 352 and the p-type electrode finger 362 is d, the direction in which the n-type electrode finger 352 and the p-type electrode finger 362 extend The width of the second unit pattern structure 701 is 8d, and the length of the fourth line pattern 710 is gradually increased by 2d in length. The second unit pattern structure 701 may be formed.

According to the light emitting diode 30 of the present invention as described above, it is possible to achieve a uniform current distribution due to the electric field distribution effect in the periphery of the electrode, and to reduce the quantum well distortion due to the reduction of the strain- The efficiency deterioration of the high-output light-emitting diode 30 can be improved.

The surface area of the light emitting region contacting the air layer is increased due to the formation of the first pattern portion 300 and the second pattern portion 700 and the internal reflection and reabsorption of photons generated inside the light emitting diode 30 is reduced The light extraction efficiency of the light emitting diode 30 can be improved.

30: Light emitting diode
300: first pattern portion
310: Base substrate
320: n-type substrate layer
330: p-type substrate layer
340: active layer
350: n-type electrode pad
352: n-type electrode finger
360: p-type electrode pad
362: a p-type electrode finger
370: transparent electrode
700: second pattern portion
752: an n-type sub finger

Claims (6)

A base substrate;
A p-type electrode pad formed on the base substrate to form a pn junction structure of a semiconductor and connected to an external power source, and a main substrate layer on which an n-type electrode pad is formed;
A transparent electrode forming an upper portion of the main substrate layer; And
Type electrode fingers extending from the n-type electrode pads and the p-type electrode fingers extending from the p-type electrode pads, and the upper portion of the transparent electrode corresponding to at least a part of the region between the n- A first pattern part connected in a maze shape;
A light emitting diode having a meander shape,
Wherein the first pattern unit has a plurality of first unit pattern structures arranged to continuously divide a direction in which the n-type electrode fingers or the p-type electrode fingers are extended.
The method according to claim 1,
Wherein the first pattern portion is etched to a depth from the transparent electrode to the n-type substrate layer.
delete A base substrate;
A p-type electrode pad formed on the base substrate to form a pn junction structure of a semiconductor and connected to an external power source, and a main substrate layer on which an n-type electrode pad is formed;
A transparent electrode forming an upper portion of the main substrate layer;
An n-type electrode finger extending from the n-type electrode pad;
A p-type electrode finger extending horizontally from the p-type electrode pad to the n-type electrode finger;
At least one or more n-type sub-fingers extending perpendicular to the p-type electrode fingers from a position spaced apart from the n-type electrode fingers by a predetermined distance; And
Type electrode fingers defined by the n-type sub fingers and the n-type electrode fingers, and is formed by etching an upper portion of the transparent electrodes between the p-type electrode fingers and the n-type electrode fingers defined by the n-type sub fingers, A second pattern part having a labyrinth shape and connected to the electrodes;
Shaped light emitting diode.
The method of claim 4,
Wherein the second pattern unit includes a plurality of second unit pattern structures arranged in series to partition a plurality of the n-type electrode fingers and the p-type electrode fingers in a direction in which the n-type electrode fingers extend, Lt; / RTI >
The method of claim 4,
And the second pattern portion is etched to a depth from the transparent electrode to the n-type substrate layer.

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