KR20170138247A - HIGH-EFFICIENCY GaN-BASED LIGHT-EMITTING DIODES AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

The present invention provides a high efficiency GaN-based light emitting diode and a manufacturing method thereof, the diode including: a substrate; a GaN-based first conductive semiconductor layer; a GaN-based conductive semiconductor layer; an active layer interposed between the first conductive semiconductor layer and the second conductive semiconductor layer; and a transparent electrode in contact with the second conductive semiconductor layer, wherein the transparent electrode includes a first electrode layer deposited by an electron-beam evaporator and a second electrode layer deposited by a sputter. The high efficiency GaN-based light emitting diode according to the present invention can obtain high light transmittance and low surface resistance.

Description

TECHNICAL FIELD [0001] The present invention relates to a GaN-based high-efficiency light emitting diode and a method of manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a gallium nitride-based high-efficiency light-emitting diode and a method of manufacturing the same. More particularly, the present invention relates to a gallium nitride-based high-efficiency light- Thereby improving the light output, and a method of manufacturing the same.

In order to fabricate gallium nitride based light emitting diodes having high efficiency / high output, light emitting diodes having a horizontal structure are most widely used and extensive researches on them have been conducted. Particularly, the biggest issue regarding this structure is the utilization as a transparent electrode for a substance which is in contact with p-type GaN, and current spreading effect, low contact resistance and high light transmittance for such a transparent electrode must be solved Is recognized as an important task.

As a prior art related to the above problem (Korean Patent No. 2001-0002265), a transparent electrode is formed by using Al ₂ O ₃ (ITO), nickel / gold (Ni / Au) An attempt has been made to fabricate light emitting diodes having characteristics and high efficiency characteristics.

However, the materials for the transparent electrode have a disadvantage in that the light extraction relative to the device area is low due to the current crowding effect. Particularly, in the ultraviolet region between 200 and 400 nm, (deep-UV) region.

In addition, ITO deposited by sputtering has a disadvantage in that formation of ohmic contact in p-type GaN is weak due to ion-damage.

Korean Patent No. 2001-0002265

Myungkwan Song, et al., "Highly efficient and bendable organic solar cells with solution-processed silver nanowire electrodes ", Adv. Funct. Mater. 23 (34), 4272 (2013)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a semiconductor device having excellent current spreading effect, low contact resistance, and low- And to provide a gallium nitride-based high-efficiency light-emitting diode which provides an excellent light transmittance even in the region.

According to a preferred embodiment of the present invention, there is provided a substrate comprising: a substrate; A gallium nitride based first conductivity type semiconductor layer; A second conductive semiconductor layer of gallium nitride type; An active layer interposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; And a transparent electrode in contact with the second conductive type semiconductor layer, wherein the transparent electrode surrounds the first electrode layer of a dot pattern in contact with the surface of the second conductive type semiconductor layer and the first electrode layer of the second conductive type semiconductor layer, And a second electrode layer that is in contact with the conductive type semiconductor layer can be provided.

The first electrode layer may be deposited by an e-beam evaporator, and the second electrode layer may be a sputtered electrode layer.

The dot pattern of the first electrode layer may be in the form of a hemispherical lens having a diameter of 1 to 10 mu m and a thickness of 10 to 200 nm.

The thickness of the second electrode layer may be 10 to 200 nm.

According to another preferred embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: depositing a first conductive semiconductor layer on a substrate; Depositing an active layer on the first conductive semiconductor layer; Depositing a second conductive type semiconductor layer on the active layer; Depositing a first electrode layer on the second conductivity type semiconductor layer, the first electrode layer having a pattern formed by an e-beam evaporator; And depositing a second electrode layer by sputtering on the first electrode layer. The present invention also provides a method of manufacturing a gallium nitride-based high-efficiency light emitting diode.

According to another preferred embodiment of the present invention, the method of manufacturing a light emitting diode may further include a step of heat-treating the transparent electrode for 30 to 600 seconds at a temperature of 300 to 900 DEG C in a nitrogen and oxygen atmosphere.

The gallium nitride-based high-efficiency light emitting diode according to the present invention is excellent in current spreading effect and light extracting effect, exhibits low contact resistance, and exhibits excellent light in a region of a deep-UV as well as a visible light region. Transmittance.

Further, the gallium nitride-based high-efficiency light emitting diode of the present invention provides a gallium nitride-based high-efficiency light emitting diode having the above-described excellent effect by a simple method and is expected to be very useful in this field.

1 is a schematic view of a gallium nitride-based high efficiency light emitting diode (Figs. 1A and 1B) according to one preferred embodiment of the present invention.
Fig. 2 is a schematic view of a gallium nitride-based light emitting diode (Figs. 2A and 2B) using ITO of electron beam deposition of Comparative Example 1 as a transparent electrode.
3 is a graph showing the results of measurement of light transmittance of a transparent electrode film according to a preferred embodiment of the present invention and the electrode films of Comparative Examples 1 and 2.
4 is a graph showing a contact resistance of the transparent electrode film according to one preferred embodiment of the present invention and the IV curve of the electrode film of Comparative Example 1.
5 is a Scanning Electron Microscopy (SEM) image of a transparent electrode film structure according to an embodiment of the present invention.
6 is a graph showing optical characteristics of a gallium nitride-based high-efficiency light emitting diode and a comparative example 1 light emitting diode according to another embodiment of the present invention.
FIG. 7 is a graph illustrating electrical characteristics of a gallium nitride-based high-efficiency light emitting diode and a comparative example 1 light emitting diode according to another embodiment of the present invention.
FIG. 8 is a graph (FIG. 8A) of electroluminescence (EL) spectra of a gallium nitride-based high-efficiency light emitting diode according to another embodiment of the present invention and a light emitting diode of Comparative Example 1 (Figure 8b) and graph (Figure 8c).
9 is a graph showing the results of optical microscopy (OM) and confocal scanning electroluminescence microscopy (CSEM) of a gallium nitride-based high-efficiency light emitting diode and a light emitting diode of Comparative Example 1 according to another preferred embodiment of the present invention. Image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. It is to be understood that the terms " comprises " or " having " and the like in the specification of the present invention are intended to imply the presence of any feature, number, step, operation, But do not preclude the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

It is to be understood that where a layer, film, region, plate, or the like is referred to as being "on" another portion, unless stated otherwise in this specification, .

According to an embodiment of the present invention, A gallium nitride based first conductivity type semiconductor layer; A second conductive semiconductor layer of gallium nitride type; And an active layer interposed between the first conductive semiconductor layer and the second conductive semiconductor layer; And a transparent electrode in contact with the second conductive type semiconductor layer, wherein the transparent electrode surrounds the first electrode layer of a dot pattern contacting the surface of the second conductive type semiconductor layer and the first electrode layer of the dot pattern And a second electrode layer that is in contact with the second conductivity type semiconductor layer. The present invention also relates to a technique for providing a gallium nitride-based high efficiency light emitting diode.

1 is a schematic cross-sectional view (FIG. 1A) of a gallium nitride-based high-efficiency light emitting diode according to a preferred embodiment of the present invention and a schematic view thereof (FIG. 1B).

1, a light emitting diode 100 according to an embodiment of the present invention includes a substrate 10, a semiconductor optoelectronic structure 10 disposed on the substrate, (20) and a transparent electrode (40).

The substrate 10 is not particularly limited as long as it is usually used as a semiconductor substrate. More specifically, the substrate 10 may be a substrate for growing a semiconductor monocrystal, and more specifically, may be a sapphire substrate, Al ₂ O ₃ , AlN, BN, GaAs, GaN, LiAlO ₂ , LiGaO ₂ , MgAl ₂ O ₄ , MgO, silicon (Si), silicon carbide (SiC), zinc oxide (ZnO), glass and the like.

For example, when the substrate 10 is formed of sapphire, the sapphire has a Hexa-Rhombo R3c symmetry, and has a concavo-convex constant of 13.001 angstroms in the c-axis direction and 4.765 angstroms in the a- And may have a C (0001) plane, an A (1120) plane, an R (1102) plane or the like as an orientation plane of the sapphire. In the case of the C-plane of the sapphire substrate layer, the nitride thin film can be easily grown and stable at high temperature.

The substrate 10 may have a thickness of 100 to 600 mu m. When the thickness is within the above range, it is possible to exhibit an appropriate supporting force for the light emitting diode formed on the substrate. More specifically, the substrate may have a thickness of 200 to 400 [mu] m.

The light emitting diode 100 converts light energy into light energy to emit light, or converts light energy into electric energy. The light emitting diode 100 can be used without any particular limitation as long as it is commonly used in the related art .

In particular, when the light emitting diode 100 includes the nitrogen-based semiconductor optoelectronic structure 20, the semiconductor optoelectronic structure 20 includes the undoped semiconductor layer 21, the first conductivity type semiconductor layer 22, A second conductive semiconductor layer 23, and a second conductive semiconductor layer 24 are sequentially stacked.

In the light emitting diode 100, the first conductive semiconductor layer 22 may include a nitride semiconductor doped with a first conductive impurity. Specifically, the nitride semiconductor may be Al _x In _y Ga _(1-xy) N (where 0? X? 1, 0? _{Y ? 1} , 0? X + y? 1) GaN, AlGaN, InGaN, or the like. The first conductive impurity doped in the nitride semiconductor may be an n-type impurity, and may be specifically Si, Ge, Se, Te, or the like.

The first conductive semiconductor layer 22 may have a thickness of 1 to 20 μm, more preferably 1 to 10 μm, in consideration of the influence of the first conductive semiconductor layer on the performance of the light emitting diode.

In the light emitting diode 100, the active layer 23 located on the first conductivity type semiconductor layer 22 is a region where electrons and holes are recombined, and includes a quantum well layer and a quantum barrier layer. When the semiconductor optoelectronic structure is a light emitting device, the active layer emits light having a predetermined wavelength, and when the semiconductor optoelectronic structure is a light receiving device or a photovoltaic power generating device, the active layer absorbs light having a predetermined wavelength. Therefore, the wavelength of the light emitted or absorbed by the active layer may vary depending on the type of the material constituting the active layer.

Specifically, when the LED 100 is a nitrogen-based light-emitting diode wherein the active layer 23 is In _x Ga ₁ so that the band gap energy is adjusted to the indium _{content-semiconductor} material, such as _{x N (0 <x <1} ) . &Lt; / RTI &gt;

In addition, the active layer 23 may have a multi-quantum well (MQW) structure in which a quantum barrier layer and a quantum well layer are alternately stacked. Specifically, the active layer may be formed by repeatedly laminating InGaN and GaN, and may be formed by repeatedly laminating AlGaN and GaN.

Considering the influence of the active layer on the performance of the light emitting diode, the active layer 23 may have a thickness of 0.1 to 20 탆, preferably 1 to 10 탆.

Meanwhile, in the semiconductor optoelectronic structure 20, the second conductive semiconductor layer 24 located on the active layer 23 may include a nitride semiconductor doped with a second conductive impurity. Specifically, the nitride semiconductor may be Al _x In _y Ga _(1-xy) N (where 0? X? 1, 0? _{Y ? 1} , 0? X + y? 1) GaN, InN, AlGaN, InGaN, or the like. The second conductivity type impurity to be doped in the nitride semiconductor may be a p-type impurity, specifically, Mg, Zn, Be, or the like.

The second conductive semiconductor layer 24 may have a thickness of 0.01 to 1 탆, preferably 0.05 to 0.1 탆, in consideration of the influence of the second conductive semiconductor layer on the performance of the light emitting diode.

Meanwhile, although the first and second conductivity type semiconductor layers are described as n-type and p-type semiconductor layers, respectively, they may be p-type and n-type semiconductor layers, respectively.

Each of the first and second conductivity type semiconductor layers may be independently a single layer or may have a multilayer structure of two or more layers.

In addition, in the light emitting diode 100, the nitride semiconductor layer 21 may be further included under the first conductivity type semiconductor layer 22, that is, on the surface side of the first conductivity type semiconductor layer in contact with the substrate.

Specifically, the nitride semiconductor layer 21 includes a nitride semiconductor of Al _x In _y Ga _(1-xy) N (where 0? X? 1, 0? _{Y ? 1} , 0? X + y? 1) And more specifically GaN, AlGaN, InGaN, or the like.

The nitride semiconductor layer 21 may be formed according to a conventional method of forming a nitride semiconductor layer, such as a vapor deposition method, or may be formed by a nitride semiconductor layer in a semiconductor optoelectronic structure, And may include semiconductors.

The nitride semiconductor layer 21 may have a thickness of 0.1 to 20 탆, more preferably 1 to 10 탆, in consideration of the remarkable effect of improving the performance of the light emitting diode upon formation thereof.

In addition, the transparent electrode 40 forming the ohmic contact with the second conductivity type semiconductor layer (or the p-type nitride semiconductor layer) in the semiconductor optoelectronic structure described above is located.

The transparent electrode 40 serves to uniformly supply power from the outside through the first metal electrode 43 or the p-type electrode located on the transparent electrode to the second conductivity type semiconductor layer 24.

The transparent electrode 40 including the first electrode layer 41 and the second electrode layer 42 of the present invention may be formed of a material such as ITO, IZO, ZnO ₂ , RuO _x , TiO _x , IrO _x , SiO ₂ , Al ₂ O ₃ , The transparent conductive material may include a composition for forming a transparent electrode. More specifically, the transparent conductive material in the present invention may be a tin oxide (ITO) doped with a Group 13 element, specifically, indium (In) have. The ITO may be specifically doped with In or In ₂ O ₃ in SnO ₂ in an amount of 0.1 to 5 wt%, or 0.1 to 2 wt%. The first electrode layer 41 constituting the transparent electrode 40 of the present invention is an electrode layer deposited by an electron beam evaporator and the second electrode layer 42 is an electrode layer deposited by sputtering. Lt; / RTI &gt;

The first electrode layer 41 may be formed by patterning using a photolithography process and the first electrode layer 41 may be formed by a dot having a contact with the surface of the second conductivity type semiconductor layer 24 ) It can take the form of a pattern. More preferably, the first electrode layer 41 is formed in a hemispherical lens shape having a diameter of 1 to 10 μm based on a scanning electron microscope (SEM) or a transmission electron microscope (TEM) It is possible to form a dot pattern, and more preferably, a very flattened hemispherical lens dot pattern can be formed. In addition, the area of the dot pattern may be formed by 1 to 5% of the area where the second electrode layer 42 is deposited.

When the diameter of the pattern is less than 1 占 퐉 or the contact area of the pattern is less than 1%, the effect of forming the hybrid electrode layer due to the pattern formation may be reduced, and the diameter of the pattern may exceed 10 占 퐉 or the contact area If it exceeds 5%, the electron beam evaporation method may fail to exhibit high light transmittance and low sheet resistance characteristics as compared with the ITO electrode layer deposited with the entire transparent electrode layer.

The first electrode layer 41 may have a thickness of 10 to 200 nm in the electrode layer deposited by the electron beam evaporation method. If the thickness of the electrode layer deposited by the electron beam evaporation method is less than 10 nm, a problem may be caused to form an ohmic contact. If the thickness exceeds 200 nm, a light transmittance may be deteriorated.

The second electrode layer 42 may be in contact with the second conductive semiconductor layer 24 while covering the first electrode layer 41. The second electrode layer 42 may have a thickness of 10 to 200 nm. When the thickness of the second electrode layer 42 is less than 10 nm, the electrode layer deposited by the electron beam evaporation method may not be sufficiently covered. If the thickness of the second electrode layer 42 is more than 200 nm, the light transmittance may be deteriorated.

In general, the p-type nitride semiconductor layer has a resistance of several ohms in a vertical direction and a resistance of several hundreds of kilohms in a horizontal direction, so that no current flows in the horizontal direction and a current flows only in the vertical direction. Therefore, when power is locally applied to the p-type nitride semiconductor layer, current does not flow through the p-type semiconductor layer as a whole, so that current can flow through the p-type semiconductor layer as a whole with excellent conductivity, It may be desirable to form a transparent electrode using a transparent conductive material so that light can be transmitted well.

The transparent electrode 40 including the transparent conductive material may have a thickness of 200 to 500 nm considering the influence on the performance of the light emitting diode.

The light emitting diode according to the present invention may further include a first electrode 43 and a second electrode 30 spaced apart from each other on the semiconductor optoelectronic structure.

More specifically, the first electrode 43 may be a p-type electrode located on the transparent electrode, and the second electrode 30 may be formed on the first conductive type semiconductor layer 22, And may be an n-type electrode spaced apart from the active layer 23 and the second conductivity type semiconductor layer 24.

The first electrode 43 and the second electrode 30 may also be used without any particular limitation as long as they are commonly used in the related art depending on the type of light emitting diode. More specifically, the first and second electrodes may be formed of a metal such as Ti, Cr, Au, Al, Ni, Ag or Zn. , Or alloys thereof.

The first electrode and the second electrode may have a single layer structure or a multilayer structure of two or more layers. The first electrode (or the p-type electrode) may have a plurality of .

More specifically, the first electrode (or the p-type electrode) 43 is a Ti / Au electrode layer sequentially deposited, and the second electrode (or the n-type electrode) 30 includes one or more metal electrode layers 31, 32, and more preferably a Ti / Al electrode layer 31 and a Ti / Au electrode layer 32 may be sequentially deposited.

The first electrode 43 and the second electrode 30 may each independently have a thickness of 100 to 200 nm.

More specifically, the gallium nitride-based high-efficiency light emitting diode of the present invention includes a sapphire substrate; A lower GaN layer located on the substrate; A gallium nitride based n-type semiconductor layer located on the lower GaN layer; A gallium nitride-based p-type semiconductor layer located on the n-type semiconductor layer; An InGaN / GaN active layer interposed between the n-type semiconductor layer and the p-type semiconductor layer; And a transparent electrode including an electrode layer deposited on the p-type semiconductor layer by an electron-beam evaporator and a sputtered electrode layer, wherein the InGaN / And may be an active layer including a multi-quantum well.

The gallium nitride-based high-efficiency light-emitting diode of the present invention is characterized in that a transparent electrode in contact with a gallium nitride-based p-type semiconductor layer is formed by an electrode layer deposited by an electron-beam evaporator and an electrode layer deposited by sputtering Known techniques applied in the field of gallium nitride-based high-efficiency light-emitting diodes in this field are not limited to the present invention, except for the above and below.

A gallium nitride-based high-efficiency light-emitting diode of the present invention provides a low contact resistance of 24.2 Ω / sq and a very low surface resistance of 1.5x10 ^-3 Ω · cm ^2.

In addition, the high efficiency light emitting diode using the electrode layer deposited by the electron-beam evaporator of the present invention and the electrode layer deposited by sputtering has a light transmittance characteristic of 450 nm as a transparent electrode, It has a very high light transmittance of 93%, which is 8% higher than the transparent electrode deposited only by the conventional electron beam evaporation method in the wavelength region, so that it has excellent light transmittance in the deep-UV region as well as the visible light region to provide.

In addition, current spreading lengths of up to 320 탆 (3 V) can effectively prevent current crowding phenomenon in a wide area device.

Therefore, the gallium nitride-based high-efficiency light emitting diode including the electrode layer deposited by the electron-beam evaporator and the electrode layer deposited by the sputtering method according to the embodiment of the present invention can be manufactured by the conventional electron beam evaporation method only It is possible to obtain a light output characteristic of 30% or more higher than that of a light emitting diode using a deposited transparent electrode.

According to another embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: depositing a first conductive semiconductor layer on a substrate; Depositing an active layer including a multi-quantum well on the first conductive semiconductor layer; Depositing a second conductive semiconductor layer on the active layer; Depositing a first electrode layer on the second conductive semiconductor layer, the first electrode layer having a pattern formed by an e-beam evaporator; And depositing a second electrode layer on the first electrode layer by a sputtering method. The present invention also relates to a method of manufacturing a gallium nitride-based high-efficiency light emitting diode.

More specifically, the method of fabricating the gallium nitride-based high-efficiency light emitting diode includes: laminating a lower GaN layer on a sapphire substrate; Forming a gallium nitride based n-type semiconductor layer on the lower GaN layer; Forming an InGaN / GaN active layer on the n-type semiconductor layer; Forming a gallium nitride based p-type semiconductor layer on the active layer; Depositing an electron beam evaporation deposition electrode layer patterned on the p-type semiconductor layer by an e-beam evaporator; And depositing a sputtered deposition electrode layer on the electron beam evaporated deposition electrode layer by sputtering.

The first electrode layer may have a thickness of 10 to 200 nm, and the first electrode layer may be formed in a pattern of a dot pattern, more preferably a hemispherical lens having a diameter of 1 to 10 mu m .

The thickness of the second electrode layer may be 10 to 200 nm.

The method of claim 1, wherein the first electrode layer and the second electrode layer are formed on the first electrode layer and the second electrode layer, respectively. 900 C &lt; / RTI &gt; for 30 to 600 seconds.

The first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer may be formed by a conventional method in the semiconductor optoelectronic structure. Specifically, metalorganic chemical vapor deposition (MOCVD) A first conductive semiconductor forming material, an active layer forming material, and a second conductive semiconductor forming material are formed on a thermal conductive layer by a method such as vapor deposition, hydrogen vapor phase epitaxy (HVPE), MOCVD or molecular beam epitaxy (MBE) 2-conductivity type semiconductor forming materials, respectively. At this time, the first conductive type semiconductor forming material, the active layer forming material, and the second conductive type semiconductor forming material may be the same as described above.

Meanwhile, in the light emitting diode according to the present invention, the second electrode is located apart from the active layer and the second conductivity type semiconductor layer on the exposed first conductivity type semiconductor layer. Accordingly, after the formation of the semiconductor optoelectronic structure, the active layer and the second conductivity type semiconductor layer are partially etched to form a second electrode to expose a portion of the first conductivity type semiconductor layer.

The etching process may be performed according to a conventional method. In the present invention, the etching process may be performed using a mesa-dry etching (ICP-RIE) method.

In the case where the light emitting diode further includes a nitride semiconductor layer between a surface of the light emitting diode and a surface in contact with the thermal conductive layer below the first conductive semiconductor layer, the manufacturing method may further include forming a nitride semiconductor layer after formation of the thermal conductive layer have. At this time, the method of forming the nitride semiconductor layer may be performed according to a conventional method of forming a semiconductor layer, such as deposition, and the material for forming the nitride semiconductor layer is the same as described above.

The transparent electrode forming process may be performed according to a conventional method. Specifically, the transparent electrode may be formed by depositing an electrode layer patterned by a first electron beam evaporation method for forming a transparent electrode, Or by depositing it in the form of a thin film using a RF magnetron sputtering system. The transparent conductive material for forming the transparent electrode used herein may be the same as described above.

Next, the first and second electrode forming processes may be performed.

The method of forming the first and second electrodes may be performed according to a conventional electrode forming method using the electrode forming material as described above.

The light emitting diode manufactured by the above-described manufacturing method has a structure in which an ITO layer formed by evaporation and patterning is formed between a transparent electrode and a p-type nitride semiconductor layer by an e-beam evaporator, And the electrical and optical characteristics of the transparent electrode are improved, so that a high light extraction efficiency can be obtained. Accordingly, the light emitting diode is useful for LED lighting requiring high light output such as TV, illumination, automobile, and the like.

Specifically, the light emitting diode includes an optical element including a photodiode, a laser diode, a light detecting element, or a solar cell; Or a thin film transistor.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by the following examples. The following examples can be appropriately modified and changed by those skilled in the art within the scope of the present invention.

[Example]

A GaN thin film layer was formed on the sapphire substrate by horizontal growth of GaN by the MOCVD method, and subsequently, n-GaN, MQW (Multi Quantum Well) and p-GaN were successively grown on the GaN thin film layer to fabricate a light emitting diode structure.

As the transparent electrode, an e- beam evaporator ITO-dot / sputtered ITO double layer according to an embodiment of the present invention was used.

First p-GaN on the e- beam deposition (e -beam evaporator) at a temperature of 500 ℃ be formed by 2% of the total contact area between the ITO pattern of the semi-spherical lens in the form of size 5 ㎛ x 5 ㎛, Ar: O 2 gas ( 10: 2) atmosphere and an operating pressure of 10 mTorr for 6 minutes, followed by rapid thermal annealing at 700 DEG C for 5 minutes under a nitrogen atmosphere to form a 100 nm thick patterned e- beam evaporator ITO-dot layer .

Then, using a radio-frequency magnetron sputtering system having an RF power of 100 W on a patterned e- beam evaporator ITO-dot layer, an Ar: O ₂ gas (ratio of 10: 2 ) Atmosphere and an operating pressure of 10 mTorr for 6 minutes and then subjected to rapid thermal annealing for 1 minute at a temperature of 550 DEG C in an oxygen atmosphere to prepare an ITO layer deposited by a sputtering method with a thickness of 100 nm, An e- beam evaporator ITO-dot / sputtered ITO double layer (e-ITO / s-ITO) according to an embodiment of the present invention was prepared.

The inductively coupled plasma reactive ion etching system using a conventional photolithography method and a dry etching method was used to make a rectangular mesa having a thickness of about 0.6 μm. Next, Ti / Al / Ti / Au (30/70/30/70 nm) and ZnO TCEs were formed on the exposed n-GaN layer and the topmost p-GaN layer, respectively, to form n-contact and p-contact. Finally, Ti / Au (50/30 nm) pull pads were selectively deposited on the n- and p-contacts to produce light emitting diodes.

1 is a schematic cross-sectional view (FIG. 1A) and a schematic view (FIG. 1B) of a gallium nitride-based high-efficiency light emitting diode according to a preferred embodiment of the present invention.

[Comparative Example 1]

e -beam evaporator ITO film (ITO-e) are e- beam deposition (e -beam evaporator) temperature, Ar of 500 ℃ using the system on a sapphire substrate: O ₂ gas (10: 2 ratio) atmosphere, and 10 mTorr for 10 minutes, followed by rapid thermal annealing for 1 minute at a temperature of 550 DEG C in an oxygen atmosphere. The thickness of the entire e-ITO transparent electrode layer was 300 nm.

The light emitting diode was fabricated in the same manner as in Example 1 except that the transparent electrode was fabricated.

Fig. 2 is a schematic view of a gallium nitride-based light emitting diode (Figs. 2A and 2B) using ITO of electron beam deposition of Comparative Example 1 as a transparent electrode.

[Comparative Example 2]

The sputtered ITO film (s-ITO) was deposited on a sapphire substrate using an RF magnetron sputtering system with an RF power of 100 W at a temperature of 500 ° C, an Ar: O ₂ gas (10: 2 ratio) atmosphere, and an operating pressure of 10 mTorr For 6 minutes. Then, rapid thermal annealing was performed for 1 minute under an oxygen atmosphere at a temperature of 550 DEG C, and the thickness of the s-ITO transparent electrode layer was 100 nm.

The light emitting diode was fabricated in the same manner as in Example 1 except that the transparent electrode was fabricated.

[Experimental Example 1] Electron beam evaporation deposition and vacuum deposition electrode film formation and physical property evaluation

In order to evaluate the physical properties of the electrode film used as a transparent electrode in the production of the light emitting diode according to the Examples and Comparative Examples 1 and 2, the ohmic contact of the surface was observed through the transmittance, the contact resistance and the SEM image.

FIG. 3 is a graph showing the results of measurement of light transmittance of the transparent electrode film according to one preferred embodiment of the present invention and the electrode films of Comparative Example 1 and Comparative Example 2, and FIG. 4 is a graph showing the results of measurement of light transmittance of the transparent electrode film according to a preferred embodiment of the present invention. FIG. 5 is a scanning electron microscope (SEM) image of a transparent electrode film structure according to an embodiment of the present invention. FIG. 5 is a graph showing the contact resistance of the electrode film of Comparative Example 1 through an IV curve of the electrode film.

The measured light transmittance and sheet resistance values ( R _sh ) in FIG. 3 were measured using a UV / VIS spectrometer (V-670EX) and a four-point probe system (CMT-SR1000N). The e-ITO / s-ITO film of the example showed a transmittance of 93.1% in the wavelength range of 450 nm. The e-ITO film of Comparative Example 1 showed a transmittance of 85.0% and showed a lower transmittance than the Example of the present invention. The s-ITO film of Comparative Example 2 showed a transmittance similar to that of the Example with a transmittance of 93.4%. It can be seen that the transparent conductive film of the present invention exhibits high light transmittance not only in the blue wavelength (450 nm) but also in the near-UV region (200-400 nm). In addition, the sheet resistance values of Examples and Comparative Examples 1 and 2 were measured to be 24.2? / Sq, 12.7? / Sq and 35.8? / Sq, respectively.

As shown in FIG. 4, the electrical characteristics of the transparent electrode films of Examples and Comparative Example 1 were analyzed. As a result, a linear curve was observed on the IV curve. As a result, the contact resistance value of the example was as low as 1 × 10 ^-3 Ω · cm ² Respectively. In the case of the embodiment, it was confirmed that the sheet had a relatively low sheet resistance value and contact resistance value, and it was confirmed that the ohmic was formed.

Fig. 5 shows an SEM image of the e-ITO / s-ITO bilayer of the embodiment. Through this, it was found that an interfacial void was formed on the contact surface with the p-GaN in the cross section (red square) of the ITO layer deposited only by the sputtering method. On the electron beam evaporated ITO layer of the hemispherical lens type, sputtering deposition In the cross section (blue square) of the ITO layer, it was confirmed that there was no damage between the ITO and p-GaN interface by electron beam evaporation deposition, and it was judged that ohmic contact was formed through this portion.

 [ Experimental Example  2] electron beam Evaporation deposition  And vacuum deposition The electrode membrane  Performance evaluation of light emitting diodes including

The following performance evaluations were performed to evaluate the optical characteristics, electrical characteristics, and light extraction characteristics of the LEDs according to the above-described Examples and Comparative Examples 1 and 2.

FIG. 6 is a graph illustrating optical characteristics of a gallium nitride-based high-efficiency light emitting diode and a comparative example 1 light emitting diode according to another embodiment of the present invention. FIG. 8 is a graph showing the electrical characteristics of the gallium nitride-based high-efficiency light emitting diode according to another embodiment of the present invention and the electro-luminescence of the light emitting diode of Comparative Example 1, , EL) spectrum (Fig. 8A), the results for the current spreading length (Fig. 8B) and the graph (Fig. 8C). 9 is a graph showing the results of optical microscopy (OM) and confocal scanning electroluminescence microscopy (CSEM) of a gallium nitride-based high-efficiency light emitting diode and a light emitting diode of Comparative Example 1 according to another preferred embodiment of the present invention. Image.

As a result of comparing the light emitting characteristics of the light emitting diode of the Example and the light emitting diode of Comparative Example 1 as shown in FIG. 6, when a horizontal light emitting diode LED device was fabricated using the e-ITO / s- It was confirmed that the optical characteristics were improved by 32.8% as compared with the LED using the e-ITO film of Comparative Example 1 as a transparent electrode.

As a result of analyzing the electrical characteristics through the IV curve of the light emitting diode of the embodiment and the light emitting diode of the comparative example 1 as shown in FIG. 7, the electrical characteristics also showed an output of 3.75 V in comparison with the 3.7 V value of the comparative example 1 , Which is a good level.

In FIG. 8A, the electroluminescence characteristics of the light emitting diodes of the embodiment and the comparative example 1 were analyzed through the intensity spectrum according to the emission wavelength. In the case of the light emitting diode of the embodiment (blue dotted line), the light emission characteristic was about 30% or more stronger, which was visually confirmed to be brighter than the comparative example (black solid line).

In FIG. 8B, a test pattern having a mesa area of 100 to 1,200 .mu.m was manufactured. When a current of 5 mA was injected, the light emission characteristics of the light emitting diode were visually confirmed. In FIG. 8C, And converted into a graph. FIG. 8B shows that the light emitting diode according to the embodiment of the present invention exhibits a low efficiency, in which light is emitted only at the edge of the mesa, while light is uniformly and strongly emitted from the entire area. As a result of calculation of the current spreading length as shown in FIG. 8C, it was confirmed that the light emitting diode of the present invention had an excellent current spreading length of about 300 μm or more when 3 V was injected. This was much higher than the actual permissible mass production of 120 μm.

In FIG. 9, light emitting diodes of Example and Comparative Example 1 were fabricated with a 500 x 500 탆 ² chip, and under the conditions of injection of 5 mA, optical microscopy (OM) and Confocal Scanning Electroluminescence Microscopy , CSEM) to observe the shape of the light locally. In the case of the light emitting diode of the embodiment, it was confirmed that light is emitted strongly around a hemispherical pattern of a lens-shaped evaporated evaporated electron beam. In the case of the light emitting diode of Comparative Example 1, It was confirmed that relatively weak light was emitted.

Therefore, the gallium nitride-based high-efficiency light emitting diode according to an embodiment of the present invention uses an ITO electrode deposited by sputtering with a low resistance / high transmittance characteristic, and a p-type GaN layer and a sputtered By adopting the structure in which the ITO pattern layer deposited by the electron-beam evaporator is inserted between the ITO layers through the patterning process, the light extracting structure and the lens structure for emitting light are employed, A gallium nitride-based high-efficiency light emitting diode having high current spreading effect as well as contact formation can be manufactured.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Those skilled in the art will readily appreciate that various changes, modifications and alterations can be made herein without departing from the spirit and scope of the invention as defined by the following claims and accompanying drawings.

100, 200: light emitting diode 10: substrate
20: Semiconductor optoelectronic structure 21: Nitride semiconductor layer
22: first conductivity type semiconductor layer 23: active layer
24: second conductive type semiconductor layer
30: second metal electrode 31, 32: metal electrode layer
40, 50: transparent electrode 41: first electrode layer
42: second electrode layer 43, 52: first metal electrode
51: metal oxide electrode layer

Claims (6)

Board;
A gallium nitride based first conductivity type semiconductor layer;
A second conductive semiconductor layer of gallium nitride type;
An active layer interposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; And
And a transparent electrode contacting the second conductive semiconductor layer,
The transparent electrode includes a first electrode layer of a dot pattern contacting the surface of the second conductive type semiconductor layer and a second electrode layer surrounding the first electrode layer of the dot pattern and contacting the second conductive type semiconductor layer And a gallium nitride-based high-efficiency light-emitting diode. The method according to claim 1,
The first electrode layer is deposited by an e-beam evaporator,
And the second electrode layer is deposited by sputtering an electrode layer. The method according to claim 1,
Wherein the dot pattern of the first electrode layer has a diameter of 1 to 10 mu m and a thickness of 10 to 200 nm in the form of a hemispherical lens. The method according to claim 1,
And the second electrode layer has a thickness of 10 to 200 nm. Depositing a first conductive semiconductor layer on the substrate;
Depositing an active layer on the first conductive semiconductor layer;
Depositing a second conductive semiconductor layer on the active layer;
Depositing a first electrode layer on the second conductive semiconductor layer, the first electrode layer having a pattern formed by an e-beam evaporator; And
And depositing a second electrode layer on the first electrode layer by sputtering. 2. The method of claim 1, wherein the first electrode layer is formed by sputtering. 6. The method of claim 5,
Further comprising the step of heat treating the transparent electrode at a temperature of 300 to 600 DEG C for 30 to 600 seconds in an atmosphere of nitrogen and oxygen.

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