WO2017057902A1

WO2017057902A1 - Electrode structure and light-emitting element comprising same

Info

Publication number: WO2017057902A1
Application number: PCT/KR2016/010870
Authority: WO
Inventors: 성태연; 김대현
Original assignee: 고려대학교 산학협력단
Priority date: 2015-09-30
Filing date: 2016-09-29
Publication date: 2017-04-06
Also published as: KR101616230B1

Abstract

An electrode structure formed on a p-type semiconductor layer comprises: a metal base reflecting layer, which is formed on the p-type semiconductor layer, and which comprises a metal base and a diffusing material; a metal electrode, which is formed on the upper portion of the metal base reflecting layer, and which is made of a metal; and a diffusion suppressing film interposed between the metal base reflecting layer and the metal electrode so as to suppress diffusion of the diffusing material towards the metal electrode during a heat treatment process for heat-treating the metal base reflecting layer such that the diffusing material diffuses into the p-type semiconductor layer and functions as an acceptor inside the p-type semiconductor layer.

Description

Electrode structure and light emitting device comprising the same

The present invention relates to an electrode structure and a light emitting device including the same, and more particularly, to an electrode structure that can be applied to a red light emitting device capable of increasing light extraction efficiency and a light emitting device including the electrode structure.

In general, a semiconductor light emitting device may be classified into a light-emitting diode (LED) and a laser diode (LD) that generate light when a forward current flows. In particular, LEDs and LDs have a P-N junction in common, and when a current is applied to these light emitting elements, the current is converted into photons to generate light.

In particular, the red light emitting device generally has a problem that the energy bandgap of the epitaxial layer is relatively low, and the amount of light absorption at the electrode is high, so that light extraction efficiency is low. To solve this problem, techniques for reducing the thickness of the epitaxial layer or increasing the permeability of the electrode have been used.

The red LED may be classified into a p-side up structure and an n-side up structure according to the type of the upper layer. The p-side up structure is a structure in which a p-type layer is positioned at the top of the light emitting device when an epitaxial layer is grown. The light emitting device having the side-up structure has a problem in that light extraction efficiency of the light emitting device is low due to relatively high absorption of light having a red wavelength in the epitaxial layer. In order to solve this problem, a light emitting device having an n-side up structure has been proposed.

The light emitting device having the n-side up structure is a wet-etching process of a substrate positioned under an epitaxial layer having a p-side up structure. By removing through, the n-type layer is located at the top. Therefore, light absorption in the epitaxial layer can be suppressed. That is, the end-side up structure has a reduced thickness of the epitaxial layer due to the wet etching process, so that light absorption in the epitaxial layer is reduced, and thus the end-up structure is reduced. The efficiency of the overall optical device can be increased.

Meanwhile, the electrode included in the red light emitting device is formed of an alloy such as a gold alloy regardless of the side-up structure or the side-up structure. However, in general, gold-based electrodes have low light reflectivity in the range of 85 to 88% in the red wavelength range (600 to 700 Hz), so that the light absorption of the electrodes is high, resulting in low overall light efficiency of the red light emitting device. .

In addition, a diffusion material such as zinc (Zn), beryllium (Be), tellurium (Te), and the like contained in the gold alloy diffuses into an epitaxial layer formed under the heat treatment process and is an acceptor. By playing a role, the ohmic contact characteristic of the epitaxial layer may be improved. However, during the heat treatment process, the diffusion material may diffuse toward the electrode rather than toward the epitaxial layer. In this case, since the amount of the acceptor in the epitaxial layer is relatively reduced, the current injection efficiency of the light emitting device is lowered.

In addition, there is a problem in that the reflectivity of the electrode is reduced and the light extraction efficiency of the light emitting device is reduced by inter-mixing between materials due to diffusion into the electrode during the heat treatment process.

SUMMARY OF THE INVENTION The present invention contemplates such a problem, and one object of the present invention is to provide an electrode structure capable of suppressing selective diffusion of a diffusion material and intermixing inside the electrode.

An object of the present invention is to provide a light emitting device capable of improving the current injection efficiency and light extraction efficiency by inhibiting the selective diffusion of the diffusion material and inter-mixing inside the electrode.

In order to achieve the object of the present invention, in the embodiment of the present invention, the electrode structure formed on the P-type semiconductor layer, is formed in the P-type semiconductor layer, a metal base reflective layer comprising a metal base and a diffusion material, A diffusion material formed on the metal base reflection layer and interposed between a metal electrode made of a metal, the metal base reflection layer, and the metal electrode, and heat-treating the metal base reflection layer to diffuse the diffusion material into the P-type semiconductor layer. And a diffusion suppressing film for suppressing diffusion of the diffusion material toward the metal electrode during the heat treatment step of functioning as an acceptor in the type semiconductor layer.

In one embodiment of the present invention, the diffusion material may include beryllium (Be), zinc (Zn) or tellurium (Te).

In one embodiment of the present invention, the metal electrode may include a metal having a work function of 5eV or more.

The metal electrode may include gold (Au), nickel (Ni), palladium (Pd), platinum (Pt), nickel-zinc alloy (NiZn) or nickel-beryllium alloy (NiBe).

In one embodiment of the present invention, the diffusion suppressing film may include a material having a melting point temperature of 3 times or more than the melting point (degrees Centigrade) of the diffusion material.

In one embodiment of the present invention, the diffusion suppressing film may include a material having a melting point of 2,000 ℃ or more.

In one embodiment of the present invention, the diffusion suppressing film may include tantalum (Ta), tungsten (W), molybdenum (Mo), ruthenium (Ru) or rhodium (Rh).

A light emitting device according to an embodiment of the present invention includes a PN assembly formed of a P-type semiconductor layer and an N-type semiconductor layer to form a PN junction, and an electrode structure formed on the P-type semiconductor layer, wherein the electrode structure is the P-type semiconductor. A metal base reflection layer formed on the layer and including a metal base and a diffusion material, formed on top of the metal base reflection layer, interposed between the metal electrode made of metal, the metal base reflection layer and the metal electrode, and the metal base reflection layer And a diffusion suppressing film for inhibiting diffusion of the diffusion material toward the metal electrode during a heat treatment process in which the diffusion material diffuses into the P-type semiconductor layer to function as an acceptor in the P-type semiconductor layer.

An electrode structure according to embodiments of the present invention is interposed between a metal base reflecting layer and a metal electrode, and heat-treating the metal base reflecting layer to diffuse the diffusion material into the P-type semiconductor layer as an acceptor in the P-type semiconductor layer. And a diffusion suppressing film for suppressing diffusion of the diffusion material toward the metal electrode during the heat treatment step of functioning. As a result, selective diffusion into the P-type semiconductor layer of the diffusion material and intermixing in the metal electrode are suppressed, thereby improving current injection efficiency and light extraction efficiency of the light emitting device.

1 is a cross-sectional view for describing an electrode structure according to an exemplary embodiment of the present invention.

2 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention.

3 is a cross-sectional view illustrating a light emitting device 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. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In the accompanying drawings, the size and amount of the objects are shown to be enlarged or reduced than actual for clarity of the invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "include" are intended to indicate that there is a feature, step, function, component, or combination thereof described on the specification, and other features, steps, functions, components Or it does not exclude in advance the possibility of the presence or addition of them in combination.

On the other hand, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Electrode structure

Referring to FIG. 1, an electrode structure 100 according to an exemplary embodiment of the present invention includes a metal base reflective layer 110, a metal electrode 120, and a diffusion suppressing layer 130.

The electrode structure 100 is formed on the P-type semiconductor layer 10. For example, the electrode structure 100 is formed on a P-type GaP layer doped with a P-type dopant. The electrode structure 100 may be applied with a voltage from the outside, and a voltage may be applied to the light emitting device through the PN junction including the P-type semiconductor layer 10.

The metal base reflective layer 110 is formed on the P-type semiconductor layer 10. The metal base reflective layer 110 may effectively reflect light generated from the light emitting device to increase light extraction efficiency of the light emitting device.

The metal base reflective layer 110 includes a metal base and a diffusion material included therein. As a result, the diffusion material may be diffused into the P-type semiconductor layer 10 to function as an acceptor in a subsequent heat treatment process for forming an ohmic contact electrode.

The metal base included in the metal base reflective layer 100 may include gold (Au), nickel (Ni), palladium (Pd), or platinum (Pt). Meanwhile, the diffusion material may include beryllium (Be), zinc (Zn) or tellurium (Te).

The metal electrode 120 is formed on the metal base reflective layer 110. The metal electrode 120 may be electrically connected to an external power source so that the power source may apply a voltage to the light emitting device through the metal electrode 120.

The metal electrode 120 may include a metal having a work function of 5 eV or more. For example, the metal electrode 120 may include gold (Au), nickel (Ni), palladium (Pd), platinum (Pt), nickel-zinc alloy (NiZn), or nickel-beryllium alloy (NiBe). have.

The diffusion suppressing layer 130 is interposed between the metal base reflective layer 110 and the metal electrode 120. The diffusion suppressing layer 130 may heat-process the metal base reflective layer 110 to diffuse the diffusion material into the P-type semiconductor layer 10 to function as an acceptor in the P-type semiconductor layer 10. The diffusion material may be prevented from diffusing toward the metal electrode 120. As a result, the diffusion material selectively diffuses toward the P-type semiconductor layer 10 without diffusing the metal electrode 120 side, whereby the concentration of the diffusion material in the P-type semiconductor layer 10 is increased. Increasingly, the diffusion material can effectively function as an acceptor in the P-type semiconductor layer.

On the other hand, by the diffusion of the diffusion material toward the metal electrode 120 is suppressed, intermixing between the metal material constituting the metal electrode 120 and the diffusion material can be suppressed. As a result, the metal base reflective layer 110 may not only have stable thermal stability but also maintain stable reflection characteristics.

The diffusion suppressing layer 130 may be formed of a material having a melting point temperature that is at least three times higher than the melting point (degrees Celsius) of the diffusion material. As a result, in the subsequent heat treatment process, the diffusion suppressing film 130 is maintained in a stable state without melting, thereby effectively suppressing diffusion of the diffusion material toward the metal electrode 120 in the heat treatment process.

The diffusion suppressing layer 130 may include a material having a melting point of 2,000 ° C. or more. For example, the diffusion suppressing layer 130 may include tantalum (Ta), tungsten (W), molybdenum (Mo), ruthenium (Ru), or rhodium (Rh).

Light emitting element

1 and 2, the light emitting device 1000 according to the exemplary embodiment includes a P-N assembly 200 and an electrode structure 100.

The P-N assembly 200 is formed of a P-type semiconductor layer 210 and an N-type semiconductor layer 260 to form a P-N junction. As a result, when a voltage is applied to the P-N assembly 200, light emission may occur through recombination of electrons and holes. The P-type semiconductor layer 20 is positioned on the P-N assembly 200. As a result, the light emitting device may have a p-side up structure.

The electrode structure 100 is formed on the P-type semiconductor layer 20.

The electrode structure 100 is formed on the P-type semiconductor layer 20 and includes a metal base reflection layer 110 including a metal base and a diffusion material, and formed on the metal base reflection layer 110, and made of metal. Interposed between the metal electrode 120, the metal base reflective layer 110, and the metal electrode 120. The metal base reflective layer 110 is heat-treated to diffuse the diffusion material into the P-type semiconductor layer 20. And a diffusion suppressing film 130 that suppresses diffusion of the diffusion material toward the metal electrode 120 during a heat treatment process to function as an acceptor in the P-type semiconductor layer 20.

Since the electrode structure 100 has been described above with reference to FIG. 1, a detailed description thereof will be omitted.

1 and 3, a light emitting device 1000 according to another embodiment of the present invention includes a P-N assembly 300 and an electrode structure 100.

The P-N assembly 300 is formed of a P-type semiconductor layer 310 and an N-type semiconductor layer 360 to form a P-N junction. As a result, when a voltage is applied to the P-N assembly 300, light emission may occur through recombination of electrons and holes. The P-type semiconductor layer 30 is positioned below the P-N assembly 300. Thus, the light emitting device may have an n-side up structure.

The electrode structure 100 is positioned between the P-type semiconductor layer 30 and the substrate 10. Since the electrode structure 100 has been described above with reference to FIG. 1, a detailed description thereof will be omitted.

The electrode structure according to the embodiments of the present invention may be applied to a light emitting device, particularly a red light emitting device. Furthermore, the electrode structure may be applied to a solar cell, a transistor having high electron mobility, a laser diode, or the like.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims

An electrode structure formed on a P-type semiconductor layer,

A metal base reflective layer formed on the P-type semiconductor layer and including a metal base and a diffusion material;

A metal electrode formed on the metal base reflective layer and made of metal; And

The diffusion material is interposed between the metal base reflection layer and the metal electrode, and the diffusion material is thermally treated in the P-type semiconductor layer by heat-treating the metal base reflection layer to function as an acceptor in the P-type semiconductor layer. An electrode structure comprising a diffusion suppressing film for inhibiting the diffusion toward the metal electrode.
The electrode structure of claim 1, wherein the diffusion material comprises beryllium (Be), zinc (Zn), or tellurium (Te).
The electrode structure of claim 1, wherein the metal electrode comprises a metal having a work function of 5 eV or more.
The metal electrode of claim 3, wherein the metal electrode comprises gold (Au), nickel (Ni), palladium (Pd), platinum (Pt), nickel-zinc alloy (NiZn), or nickel-beryllium alloy (NiBe). An electrode structure, characterized in that.
The electrode structure of claim 1, wherein the diffusion suppressing layer comprises a material having a melting point temperature that is at least three times higher than a melting point (° C) of the diffusion material.
The electrode structure of claim 1, wherein the diffusion suppressing layer comprises a material having a melting point of 2,000 ° C. or higher.
The electrode structure of claim 1, wherein the diffusion suppressing layer comprises tantalum (Ta), tungsten (W), molybdenum (Mo), ruthenium (Ru), or rhodium (Rh).
A P-N assembly comprising a P-type semiconductor layer and an N-type semiconductor layer to form a P-N junction; And

An electrode structure formed on the P-type semiconductor layer,

The electrode structure may include a metal base reflective layer formed on the P-type semiconductor layer and including a metal base and a diffusion material;

A metal electrode formed on the metal base reflective layer and made of metal; And

The diffusion material is interposed between the metal base reflection layer and the metal electrode, and the diffusion material is thermally treated in the P-type semiconductor layer by heat-treating the metal base reflection layer to function as an acceptor in the P-type semiconductor layer. And a diffusion suppressing film for suppressing diffusion toward the metal electrode.
The light emitting device of claim 8, wherein the diffusion material comprises beryllium (Be), zinc (Zn), or tellurium (Te).
The light emitting device of claim 8, wherein the metal electrode comprises a metal having a work function of 5 eV or more.
The metal electrode of claim 10, wherein the metal electrode comprises gold (Au), nickel (Ni), palladium (Pd), platinum (Pt), nickel-zinc alloy (NiZn), or nickel-beryllium alloy (NiBe). A light emitting element characterized by the above-mentioned.
The light emitting device of claim 8, wherein the diffusion suppressing layer comprises a material having a melting point temperature that is at least three times higher than a melting point (° C) of the diffusion material.
The light emitting device of claim 8, wherein the diffusion suppressing film comprises a material having a melting point of 2,000 ° C. or higher.
The light emitting device of claim 8, wherein the diffusion suppressing layer comprises tantalum (Ta), tungsten (W), molybdenum (Mo), ruthenium (Ru), or rhodium (Rh).