KR20060124833A - Rod type light emitting device and method for fabricating the same - Google Patents

Abstract

A rod-type light emitting device is provided to increase a light emitting area by forming mutually isolated rods that emit light. A first polarity layer(110) is formed. A plurality of rods(120) emit light, disposed on the first polarity layer and separated from each other. The plurality of rods are surrounded by a second polarity layer(130). The first polarity layer has an opposite polarity to the second polarity layer. A substrate(100) is located under the first polarity layer. The substrate is a conductive substrate, and an electrode is formed on each rod.

Description

Rod type light emitting device and method of manufacturing the same {Rod type light emitting device and method for fabricating the same}

1 is a conceptual diagram illustrating a path of light due to a difference in refractive index between two general media

2 is a schematic cross-sectional view showing a path of light in a general light emitting diode.

3A to 3G are cross-sectional views illustrating a manufacturing process of a rod type light emitting device according to the present invention.

4 is a cross-sectional view illustrating a state in which light is emitted to a rod-type light emitting device according to the present invention.

5 is a cross-sectional view of a rod-type light emitting device according to a first embodiment of the present invention.

6 is a cross-sectional view of a rod-type light emitting device according to a second embodiment of the present invention.

7A and 7B are cross-sectional views of a rod type light emitting device according to a third embodiment of the present invention.

8A and 8B illustrate a state in which a second polar layer protrudes from a conductive material film and a path from which light is extracted according to a third embodiment of the present invention.

9 is a cross-sectional view of a rod-type light emitting device according to a fourth embodiment of the present invention.

10A and 10B are energy band diagrams of a transparent conductive oxide film, a current transfer enhancement layer, and P-GaN before and after heat treatment according to the present invention.

<Description of the symbols for the main parts of the drawings>

100: substrate 110,130: polar layer

120: load 140: electrode

160: conductive material 200: current transfer enhancement layer

210: transparent conductive oxide film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rod type light emitting device and a method of manufacturing the same, and more particularly, by forming rods emitting light spaced apart from each other, thereby emitting light to the entire surface of the rods to increase the light emitting area, The present invention relates to a rod-type light emitting device capable of improving the light output of the device by increasing the amount of light emitted to the outside without being restrained, and a manufacturing method thereof.

In general, light emitting diodes are single wavelength light sources having various applications, such as automotive light sources, electronic signs, lighting, light sources for backlight units of displays, and the like.

Most of the light generated inside the light emitting diode is trapped inside the light emitting diode due to reflection by the critical angle at the interface such as semiconductor and air.

FIG. 1 is a conceptual diagram illustrating a path of light due to a difference in refractive index between two general media. When the first medium having a refractive index of 'n1' is advanced to a second medium having a refractive index of 'n2', According to Equation 1 according to the law of), light incident to the second medium from the first medium is transmitted smaller than the critical angle, and light incident to the second medium is totally reflected.

n1 * sin θ1 = n2 * sin θ2

Here, θ1 is an angle of incidence and θ2 is a refractive angle.

FIG. 2 is a schematic cross-sectional view illustrating a path of light in a general light emitting diode, in which an n-semiconductor layer 11, an active layer 12, and a p-semiconductor layer 13 are sequentially stacked on the substrate 10. In the light emitting diode structure, among the light emitted from the active layer 12, the light (a, b, c) traveling to the outside of the device at an angle smaller than the critical angle is transmitted.

However, the light d traveling outside of the device at an angle greater than the critical angle is totally reflected and trapped inside the device.

Therefore, when the amount of light trapped inside the device increases, the light output of the light emitting diode is reduced and the characteristics are degraded.

There are many ways to improve the light extraction efficiency in such a light emitting diode.

First, there is a method of increasing the probability of incident in the vertical direction from the chip by modifying the shape of the light emitting diode chip, the hemispherical shape of the various shapes is known to be the most theoretical, but there is a disadvantage that the manufacturing is difficult and expensive.

Secondly, although it is difficult to manufacture, there is a method of encapsulating a light emitting diode with a hemispherical epoxy dome.

Third, there is a technique of changing the substrate that reabsorbs the light emitted from the light emitting diode into a totally reflected substrate.

In addition, there is a method of manufacturing a light emitting diode having a micro cavity or resonant cavity structure, which requires very precise control and reproducibility of the thickness of the layer, etc. In order to efficiently extract the furnace light, there is a difficulty in that the emission wavelength of the light emitting diode must match the cavity mode which is accurately manufactured.

In addition, the emission wavelength of the light emitting diode has a problem in that when the temperature or operating current increases, the emission wavelength is changed and the light output is drastically reduced.

On the other hand, in recent years, in order to increase the light extraction efficiency of the light emitting diode, the surface texturing to roughen the surface of the light emitting diode chip artificially generated inside the chip or to form a regular shape which is periodically repeated on the surface ( Surface texturing techniques have been reported.

This technology can be used alone as a technology to improve the light extraction efficiency on the light emitting diode chip, in parallel with the existing methods such as the above-described technology of modifying the chip shape, epoxy encapsulation method, substrate change, etc. It can be applied to improve the light extraction efficiency even more.

Current surface texturing technology uses a method of forming a pattern with a mask and performing a wet or dry etching to form a shape on the surface.

This technique is limited in the height of the surface shape due to the constant thickness of each layer in the light emitting diode structure, and requires precise control and reproducibility of the thickness to be etched during the etching process.

In addition, there is a problem that a number of processes are required, such as pattern formation for etching.

In order to solve the above problems, the present invention forms rods that emit light spaced apart from each other, thereby emitting light to the entire surface of the rods, thereby increasing the emission area, and emitting the light to the outside without being confined to the inside of the device. It is an object of the present invention to provide a rod-type light emitting device capable of improving the light output of the device by increasing the amount of light to be made, and a manufacturing method thereof.

A preferred aspect for achieving the above objects of the present invention,

A first polarity layer;

A plurality of rods formed on the first polar layer and spaced apart from each other and emitting light;

A rod type light emitting device including a second polar layer surrounding the plurality of rods is provided.

Another preferred aspect for achieving the above object of the present invention,

Forming a flat first polarity layer on the substrate;

Forming a plurality of rods spaced apart from each other and emitting light on the first polar layer;

Provided is a method of manufacturing a rod-type light emitting device comprising forming a second polar layer surrounding the plurality of rods.

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

3A to 3G are cross-sectional views illustrating a manufacturing process of a rod type light emitting device according to the present invention. First, a first flat polarity layer 110 is formed on the substrate 100. 3a)

Thereafter, a plurality of rods 120 which are spaced apart from each other and emit light are formed on the first polar layer 110 (FIG. 3B).

Subsequently, a second polar layer 130 surrounding the plurality of rods 120 is formed (FIG. 3C).

Here, the first polar layer 110 is a layer having a polarity opposite to the second polar layer 130.

At this time, for example, if the first polar layer 110 is an n-type semiconductor layer, the second polar layer 130 is a p-type semiconductor layer.

That is, the first polar layer 110 is a layer for supplying electrons, and the second polar layer 130 is a layer for supplying holes.

The polarity applied to the first and second polar layers 110 and 130 may be freely designed.

The plurality of rods 120 correspond to an active layer that emits light.

Therefore, by performing the above-described process, it is possible to manufacture a basic rod-type light emitting device as shown in Figure 3c.

That is, the rod-type light emitting device of the present invention includes a first polar layer 110; A plurality of rods 120 formed on the first polar layer 110 and spaced apart from each other and emitting light; It is configured to include a second polar layer 130 surrounding the plurality of rods (120).

Here, it is preferable that the substrate 100 is further formed under the first polar layer 110.

In addition, the plurality of rods 120 may be an extremely fine structure having a width of a nano unit.

4 is a cross-sectional view illustrating a state in which light is emitted to a rod-type light emitting device according to the present invention. Since the plurality of rods 120 correspond to an active layer emitting light, each of the rods 120 is a whole. The light emitting area is emitted to increase the light emitting area, thereby improving the light output of the device.

In addition, since the light is emitted from each of the plurality of spaced apart rods 120, the amount of light emitted to the outside without being confined to the inside of the device is increased, so that the total reflection problem in the device as in the prior art is not concerned.

FIG. 5 is a cross-sectional view of the rod-type light emitting device according to the first embodiment of the present invention. If the substrate 100 is a conductive substrate in FIG. 3C, the electrode 140 is formed on each of the rods 120. .

In this case, since current flows from the substrate 100 to the electrode 140, electrons and holes are injected into the rods 120.

FIG. 6 is a cross-sectional view of a rod-type light emitting device according to a second embodiment of the present invention. When the substrate 100 is a non-conductive substrate in FIG. 3C, a plurality of rods may be disposed only on a portion of the first polar layer 110. Form 120.

In addition, the electrodes 140 and 150 are formed on the rods 120 and on the first polar layer on which the rods are not formed.

That is, in the rod-type light emitting device according to the second embodiment of the present invention, since current flows between the electrodes 140 and 150, electrons and holes are injected into the rods 120 so that the rods 120 emit light. do.

7A and 7B are cross-sectional views of a rod-type light emitting device according to a third embodiment of the present invention. In the third embodiment of the present invention, the conductive material 160 is disposed between the second polar layers 130 surrounding the rods 120. ).

Therefore, the conductive material 160 may smoothly supply current to the rods 120 spaced apart from each other.

At this time, the conductive material 160 is preferably a sol-gel (Sol-gel) transparent conductive material, the transparent conductive material is preferably any one of ITO, IZO, ZnO and AZO.

8A and 8B are diagrams illustrating a state in which a second polar layer protrudes from a conductive material film and a path from which light is extracted according to a third embodiment of the present invention. First, as shown in FIG. 8A, a rod The conductive material 160 is interposed between the second polar layers 130 surrounding the rods 120 such that some of the second polar layers 130 surrounding the rods 120 protrude from the conductive material 160. Fill it.

As such, if some of the second polar layers 130 surrounding the rods 120 protrude from the conductive material 160 (at a height of 'H'), the rods 120 are shown in FIG. 8B. A bend is formed on the upper side thereof, thereby further reducing the total reflection of the light emitted from the rods 120, thereby increasing the amount of light emitted.

9 is a cross-sectional view of a rod-type light emitting device according to a fourth embodiment of the present invention, in which a plurality of rods 120 are formed on the first polar layer 110, and the rods 120 are formed in a second manner. A current transport enhancement layer (CTEL) 200 and a transparent conductive oxide layer including a polarization layer 130 and a material of the second polarization layer 130 to improve carrier movement to facilitate current flow. The rod-shaped light emitting device according to the fourth exemplary embodiment of the present invention has a structure in which 210 is sequentially wrapped.

When the second polar layer 130, the current transfer enhancement layer 200, and the transparent conductive oxide film 210 are sequentially contacted with the rod as a whole, the contact resistance is remarkably lowered, and the metal electrode is not provided. Since it is not necessary, it becomes excellent in terms of luminous efficiency.

That is, when the first polar layer 110 is an n-GaN layer and the second polar layer 130 is a p-GaN layer, the current transfer enhancement layer 200 is made of a material including GaN.

In addition, the work function of the current transfer enhancement layer 200 should be smaller than the work function of the second polar layer 130 and greater than the work function of the transparent conductive oxide film 150.

In this case, referring to FIGS. 10A and 10B, when the current transfer enhancement layer and the transparent conductive oxide film are sequentially wrapped on the P-GaN layer, the energy band diagram on the interface thereof becomes the state of FIG. 10A.

Therefore, as shown in Fig. 10A, the transparent conductive oxide film in the deposited state is not in ohmic contact with the current transfer enhancement layer.

Therefore, according to the present invention, when the transparent conductive oxide film is deposited on the current transfer enhancement layer, the heat conduction process is performed to increase the work function of the transparent conductive oxide film to 4.7 to 5.3 eV. Holes can be moved smoothly, ohmic contact is made.

As described above, the present invention forms rods that emit light spaced apart from each other, thereby emitting light to the entire surface of the rods to increase the light emitting area, and increase the amount of light emitted to the outside without being confined inside the device. By doing so, there is an effect that the light output of the device can be improved.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (15)

A first polarity layer; A plurality of rods formed on the first polar layer and spaced apart from each other and emitting light; The rod-type light emitting device comprising a second polar layer surrounding the plurality of rods. The method of claim 1, The first polar layer is, A rod-type light emitting device, characterized in that the layer having a polarity opposite to the second polar layer. The method of claim 1, The rod type light emitting device of claim 1, wherein a substrate is further formed under the first polar layer. The method of claim 3, wherein The substrate is a conductive substrate, Rod-type light emitting device, characterized in that the electrode is formed on each of the rods. The method of claim 3, wherein The substrate is a non-conductive substrate, The plurality of rods are formed on a part of the first polar layer, And an electrode is formed on each of the rods and the upper portion of the first polar layer in which the rods are not formed. The method according to any one of claims 1 to 5, And a conductive material is further filled between the second polar layers surrounding the rods. The method of claim 6, The conductive material, A rod-type light emitting device comprising any one of ITO, IZO, ZnO, and AZO. The method of claim 6, And a portion of the second polar layers surrounding the rods protrude from the conductive material. A first polar layer; A plurality of rods formed on the first polar layer; A second polar layer surrounding the rods; A current transport enhancement layer (CTEL) surrounding the second polar layer, comprising a material of the second polar layer, to improve carrier movement to facilitate current flow; A rod-type light emitting device comprising a transparent conductive oxide film surrounding the current transfer enhancement layer. The method of claim 9, The first polar layer is an n-GaN layer, The second polar layer is a p-GaN layer, The current transfer enhancement layer is a rod-type light emitting device, characterized in that the material containing GaN. The method of claim 9, The work function of the current transfer enhancement layer is A rod type light emitting device which is smaller than the work function of the second polar layer and larger than the work function of the transparent conductive oxide film. Forming a flat first polarity layer on the substrate; Forming a plurality of rods spaced apart from each other and emitting light on the first polar layer; And forming a second polar layer surrounding the plurality of rods. The method of claim 12, After forming the second polar layer, And a conductive material is filled between the second polar layers surrounding the rods. The method of claim 13, The conductive material is a manufacturing method of a rod-type light emitting device, characterized in that the sol-gel (Sol-gel) transparent conductive material. The method of claim 13, Between forming the second polar layer and filling the conductive material, A process of forming a current transport enhanced layer (CTEL) surrounding the second polar layer and including a material of the second polar layer and improving carrier movement to facilitate current flow; The method of manufacturing a rod-type light emitting device, characterized in that less than the work function of the second polar layer, and larger than the work function of the conductive material.

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