KR100728132B1 - Light Emitting Diode Using Current Diffusion Layer - Google Patents

Abstract

The present invention relates to a light emitting diode using a current spreading layer. The light emitting diode of the present invention is a nitride compound light emitting diode, comprising: an active layer; A p-type semiconductor layer formed on one side of the active layer; A p-electrode formed on one side of the p-type semiconductor layer; An n-type semiconductor layer formed on the other side of the active layer; A current diffusion layer formed on one side of the n-type semiconductor layer; An n-electrode formed on one side of the current spreading layer, wherein the current spreading layer comprises a gallium nitride (GaN) layer or an indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer or silicon gallium nitride doped with a high concentration of silicon; And a (SiGaN) layer. As described above, the light emitting diode according to the present invention may improve the luminance of the light emitting diode by inserting a current diffusion layer between the n-electrode and the n-type semiconductor layer.

Description

Light Emitting Diode Using Current Diffusion Layer {LIGHT-EMITTING DIODE USING CURRENT SPREADING LAYER}

1A to 1B are conceptual cross-sectional views illustrating current spreading of a light emitting diode.

2 is a sectional view of a light emitting diode according to the present invention;

3A to 3C are cross-sectional views illustrating a method of manufacturing a light emitting diode according to the present invention.

4 is a sectional view of an ultraviolet light emitting diode according to the present invention;

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

10: substrate 20: U-GaN

30: n-type semiconductor layer 40: active layer

50: p-type semiconductor layer 60: p-electrode

70: n-electrode 80: current diffusion layer

90: metal layer 100: n-type AlGaN

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode, wherein the light emitting diode is characterized by inserting a current spreading layer to increase current spreading of the p-type semiconductor layer.

In general, a light emitting diode element uses a nitride-based semiconductor material such as a mixed crystal of GaN / AlN or InN, and a light emitting diode that emits light from a visible region to an ultraviolet region using the light emitting diode element is realized. Sapphire or the like is usually used as a growth substrate of the light emitting diode element. In this case, since the substrate is an insulating substrate, an electrode must be provided to apply power to the LED device. For this purpose, in the conventional light emitting diodes of various blue to ultraviolet regions, the n-type electrode and the p-type electrode are formed on the same plane side as the horizontal light-emitting diode, or the GaN is removed from the sapphire, so that the p-type electrode is placed on the top. Various electrode structures, such as a vertical light emitting diode having an n-type electrode formed thereunder, have been proposed and used. In this case, the vertical light emitting diode may be manufactured with higher luminance than the conventional horizontal light emitting diode by removing sapphire, which is a conventional high conductive layer.

1A to 1B are conceptual cross-sectional views for describing current diffusion of a light emitting diode.

When current is applied to the p-electrode 60 of the conventional horizontal light emitting diode having no current spreading layer as shown in FIG. 1A, the current passes through the active layer 40 through the shortest distance of the p-type semiconductor layer 50 and then the n-type semiconductor layer. Flows to (30).

In addition, as shown in FIG. 1B, in the conventional vertical light emitting diode, the current supplied to the p-electrode 60 reaches the active layer 40 while being diffused while passing through the p-type semiconductor layer 50. At this time, if the p-type semiconductor layer 50 is not thick enough, the current does not sufficiently diffuse in the p-type semiconductor layer 50 and reaches the active layer 40, which causes a failure to increase the luminance. However, since the p-type semiconductor layer 50 is grown only about 2 μm in thickness, the supplied current does not sufficiently diffuse in the p-type semiconductor layer 50 and reaches the active layer 40.

If the current is not sufficiently diffused in the p-type semiconductor layer 40 as described above, the reaction occurs only in a portion of the active layer 40, it is impossible to manufacture a high-brightness light emitting diode. In order to solve this problem, increasing the thickness of the p-type semiconductor layer 40 is not a good method because it reduces the production efficiency of the light emitting diode and increases the production cost. In addition, although the p-type semiconductor layer may be grown by increasing the growth rate of the p-type semiconductor layer 40 during the same production time, the p-type semiconductor layer grown in this way is degraded in quality, so There is a problem that light is trapped in the p-type semiconductor layer.

An object of the present invention is to solve the above problems, and to improve the brightness of the light emitting diode by providing a current diffusion layer between the n-electrode and the n-type semiconductor of the light emitting diode.

In addition, another object of the present invention is that when a high current is applied to the light emitting diode, current flows in the shortest distance between the n-electrode and the adjacent metal so that sufficient current diffusion does not occur in the p-type semiconductor layer. Therefore, a current diffusion layer is provided between the n-electrode and the n-type semiconductor layer to prevent light emission from only a part of the active layer.

In order to achieve the above object, the present invention provides a nitride compound light emitting diode, comprising: an active layer; A p-electrode formed on one side of the active layer; An n-type semiconductor layer formed on the other side of the active layer; And an n-electrode formed on one side of the n-type semiconductor layer, and including a current diffusion layer and a p-type semiconductor layer between the p-electrode and the active layer.

In this case, the current diffusion layer includes a gallium nitride (GaN) layer or an indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer or a silicon gallium nitride (SiGaN) layer doped with a high concentration of silicon. Silver silane (SiH ₄ ) or disilane (Si ₂ H ₆ ) or tetraethoxysilane is used.

The high concentration silicon-doped gallium nitride (GaN) layer forms a semiconductor layer having a silicon doping level of 1 × 10 ²⁰ to 1 × 10 ²² cm ^-3 to a thickness of 30 μm to 10 μm.

The indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer uses trimethylindium and triethylindium as indium sources.

The indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer forms a growth thickness of n-type indium gallium nitride (InGaN) and n-type gallium nitride (GaN) in 1 to 30 pairs, respectively, at 10 to 1000 Å. .

The silicon gallium nitride (SiGaN) layer uses tetraethoxysilane as a silicon source.

The silicon gallium nitride (SiGaN) layer is formed to a thickness of 30 ~ 2㎛.

The current spreading layer includes a highly doped n-type Al x Ga (1-x) N in which x is 0 <x≤1; Or y includes a superlattice current spreading layer composed of n-type Al x Ga (1-y) N and n-type aluminum nitride (AlN) with 0 <y <1.

In addition, the light emitting diode includes a metal layer formed between the p-type semiconductor layer and the p-electrode. In this case, the metal layer includes nickel (Ni) / gold (Au) or silver (Ag) or copper (Cu).

The n-electrode includes at least one of nickel (Ni), aluminum (Al), titanium (Ti), gold (Au), and indium tin oxide (ITO).

Further, in the nitride compound light emitting diode, step of sequentially forming a current diffusion layer, n-type semiconductor layer, active layer, p-type semiconductor layer on the substrate; Removing the substrate; And forming an n-electrode and a p-electrode in the n-type semiconductor layer and the p-type semiconductor layer, respectively.
Forming an n-type semiconductor layer on the substrate; Sequentially forming a current spreading layer, an active layer, and a p-type semiconductor layer on the n-type semiconductor layer; Removing the substrate; It provides a method for manufacturing a light emitting diode comprising the step of forming an n-electrode and a p-electrode in the n-type semiconductor layer and the p-type semiconductor layer, respectively.

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The current diffusion layer includes a gallium nitride (GaN) layer doped with a high concentration of silicon, an indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer, or a silicon gallium nitride (SiGaN) layer. It provides a manufacturing method.

In this case, a gallium nitride (GaN) layer doped with a high concentration of silicon and a gallium nitride (GaN) layer having a silicon doping level of 1 × 10 ²⁰ to 1 × 10 ²² cm ^-3 at 30 to 10 µm at 700 to 1200 degrees Celsius. Method for producing a light emitting diode, characterized in that formed to a thickness of,

The silicon gallium nitride (SiGaN) layer provides a method of manufacturing a light emitting diode, characterized in that to form a thickness of 30 ~ 2㎛ at 700 ~ 1200 degrees Celsius.

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

However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like reference numerals in the drawings refer to like elements.

The substrate refers to a conventional wafer for fabricating a light emitting diode, and the vertical light emitting diode as shown in FIG. 2 uses at least one of sapphire or a substrate such as Si or SiC or silicon sapphire. In this embodiment, a crystal growth substrate made of sapphire is used.

The deposition and growth methods of semiconductors include metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PCVD), and molecular beam growth (PCVD). There are various methods including Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), and the like. In this embodiment, an organometallic chemical vapor deposition method is used.

In light-emitting diode fabrication, current diffusion of the p-type semiconductor layer is important for improving luminance. Thus, a layer is inserted between the active layer and the p-electrode which can increase the current spreading of the p-type semiconductor layer. That is, it may be inserted between the p-electrode and the p-type semiconductor layer, between the p-type semiconductor layer and the active layer, or the like, and if another layer is formed between the active layer and the p-electrode, it may be formed between the active layer and the other layer. Can be. In the embodiment of the light emitting diode according to the present invention, a current diffusion layer is provided at the interface between the n-electrode and the p-type semiconductor layer to increase the current diffusion of the n-type semiconductor layer.

2 is a cross-sectional view of a light emitting diode according to the present invention.

Referring to FIG. 2, the light emitting diode of the present invention includes a current diffusion layer 80, an n-type semiconductor layer 30 formed on the current diffusion layer 80, and an active layer formed on the n-type semiconductor layer 30. 40, a p-type semiconductor layer 50 formed on the active layer 40, a metal layer 90 formed on the p-type semiconductor layer 50, and a p-electrode formed on the metal layer 90 ( 60 and an n-electrode 70 formed below the current spreading layer 80.

The current diffusion layer 80 is for uniformly diffusing an external power source applied to the p-electrode 60 to a nitride semiconductor layer such as the p-type semiconductor layer 50 or the active layer 40. Nitride doped with a high concentration of silicon It is grown using a gallium nitride (GaN) layer including at least one of a gallium (GaN) layer, an indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice layer, or a silicon gallium nitride (SiGaN) layer. When power is applied to the light emitting diode on which the current spreading layer 80 is formed as described above, electrons of the n-electrode 70 are uniformly diffused throughout the n-type semiconductor layer 30 by the current spreading layer 80. Therefore, light is uniformly emitted throughout the active layer 40. At this time, since the direction in which the electrons move and the direction of the current is reversed, the diffusion of the electrons can be seen as the diffusion of the current.

The n-type semiconductor layer 30 is an electron generation layer, and is formed of an n-type compound semiconductor layer and an n-type cladding layer. The n-type semiconductor layer 30 has at least one of gallium nitride (GaN) or aluminum gallium nitride (AlGaN) and indium gallium nitride (InGaN) doped with silicon having a doping level of 1 × 10 ¹⁹ to 1 × 10 ²² cm ^-3 . The n-type semiconductor layer 30 is grown to have a structure including a single layer or a combination of these layers stacked in the form of a super lattice.

The p-type semiconductor layer 50 is a layer in which holes are formed, and is formed of a p-type cladding layer and a p-type compound semiconductor layer. The p-type semiconductor layer 50 includes a single layer of gallium nitride (GaN) or aluminum gallium nitride (AlGaN) and indium gallium nitride (InGaN) doped with p-type impurities, or a combination of each of these layers stacked in a superlattice form. The p-type GaN 50 is grown as a structure.

The active layer 40 is a region where a predetermined band gap and a quantum well are made to recombine electrons and holes, and is formed using a material such as nitride including indium gallium nitride (InGaN) or indium (In). In this case, the emission wavelength generated by the combination of electrons and holes is changed according to the type of material constituting the active layer 40. Therefore, it is preferable to use the semiconductor material whose composition was controlled according to the target wavelength as the active layer 40.

The n-electrode 70 and the p-electrode 60 are for transferring power applied from the outside to the semiconductor layer. The n-electrode 70 is formed of nickel (Ni), aluminum (Al), titanium (Ti), gold (Au), an indium tin oxide (ITO) such as a transparent conductive thin film, a transparent metal electrode, or the like. do. In addition, the p-electrode 60 is formed using chromium (Cr) or gold (Au) or chromium (Cr) / gold (Au), which is an alloy of the metal.

The metal layer 90 is formed using a metal such as nickel (Ni) / gold (Au) or silver (Ag) or copper (Cu).

Hereinafter, a method of manufacturing the light emitting diode as described above will be described.

3A to 3C are cross-sectional views illustrating a method of manufacturing a light emitting diode according to the present invention.

In the method of manufacturing a light emitting diode according to an embodiment of the present invention, as shown in FIGS. 3A to 3C, first, a buffer layer (not shown) using gallium nitride (GaN) or aluminum nitride (AlN) on a prepared substrate 10 is used. Is grown, high quality undoped gallium nitride (U-GaN) 20 is grown as a buffer layer, and undoped gallium nitride (U-GaN) 20 is grown. Thereafter, the current diffusion layer 80 is grown on the undoped gallium nitride (U-GaN) 20.
In this case, the current diffusion layer 80 includes a gallium nitride (GaN) layer doped with a high concentration of silicon or a superlattice layer or gallium nitride (SiGaN) layer formed of indium gallium nitride (InGaN) and gallium nitride (GaN).
First, the gallium nitride (GaN) layer doped with high concentration silicon uses trimethylgallium, triethylgallium and triisopropylgallium as the gallium source, and silane (SiH ₄ ) or disilane (Si ₂ H ₆ ) as the silicon source. Or tetraethoxysilane and ammonia and dimethylhydrazine are used as nitride sources to grow a gallium nitride (GaN) layer doped with a high concentration of silicon. The high concentration silicon-doped gallium nitride (GaN) layer has a high concentration of silicon having a concentration of about 1 × 10 ²⁰ to 1 × 10 ²² cm ^-3, which is 10 to 100 times higher than the n-type semiconductor layer 30. Gallium (GaN) is grown from 30 to 10 µm at 700 to 1200 degrees Celsius.
Next, when a superlattice layer including indium gallium nitride (InGaN) and gallium nitride (GaN) is formed as the current diffusion layer 80, trimethylgallium, triethylgallium, and triisopropylgallium are used as a gallium source. N-type InGaN / N-GaN superlattice layer using trimethylindium and triethylindium as indium source, silane or disilane or tetraethoxysilane as silicon source, and ammonia and dimethylhydrazine as nitride source Grow to the current spreading layer 80. The thickness of InGaN in the n-type superlattice layer used for growth is 10-1000Å, the thickness of GaN in the n-type superlattice layer is 10-1000Å, and the pair of n-type InGaN / n-type GaN grows to 1-30 pairs do.
In addition, when the silicon gallium nitride (SiGaN) layer is used as the current diffusion layer 80, trimethylgallium, triethylgallium and triisopropylgallium are used as the gallium source, and silane (SiH ₄ ) or disilane (Si ₂ ) is used as the silicon source. H ₆ ) or tetraethoxysilane is used, and a current diffusion layer 80 is formed by growing a SiGaN layer with a thickness of 30 μm to 2 μm between 700 ° C. and 1200 ° C. using ammonia and dimethyl hydrazine as a nitride source. The current diffusion layer 80 may be formed after the active layer 40 is grown, and the p-type semiconductor layer may be grown on the current diffusion layer 80.
Next, gallium nitride (GaN) or aluminum gallium nitride (AlGaN) and indium gallium nitride (InGaN) doped with silicon having a doping level of 1 × 10 ¹⁹ to 1 × 10 ²² cm ^{−3 on} the current spreading layer 80. The n-type semiconductor layer 30 is grown to a thickness of 0.5 μm to 10 μm, including a single layer, or a combination of these layers stacked in a superlattice. The active layer 40 is grown on the n-type semiconductor layer 30 by using a material such as nitride such as indium gallium nitride (InGaN) or nitride including indium (In), and the p-type impurity is deposited on the active layer 40. The p-type semiconductor layer 50 is grown in a structure in which a doped gallium nitride (GaN), aluminum gallium nitride (AlGaN), or indium gallium nitride (InGaN) is a single layer or a combination of these layers is stacked in the form of a superlattice. The structure grown under the above conditions is shown in FIG. 3A.

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Subsequently, the metal layer 90 is formed of a metal such as nickel (Ni) / gold (Au) or silver (Ag) or copper (Cu) on the p-type semiconductor layer 50. After this process, the substrate 10 is removed using a sapphire substrate lift-off technique (LLO). After removing the substrate 10, the substrate 10 is present as shown in FIG. 3B. The U-GaN 20 is removed as shown in FIG. 3C using photochemical etching, and then nickel (Ni) is formed on the n-type semiconductor layer 30. , N-electrode 70 is formed using at least one of aluminum (Al), titanium (Ti), gold (Au), and indium tin oxide (ITO), and chromium is formed on the metal layer 90. When the p-electrode 60 is formed of a metal such as (Cr) or gold (Au) or chromium (Cr) / gold (Au), a vertical light emitting diode having a shape as shown in FIG. 2 may be manufactured.

The basis of the present invention is when a blue and green light emitting diode using gallium nitride (GaN) is manufactured as a vertical light emitting diode. However, the same can be applied not only to this case but also to fabricating an ultraviolet light emitting diode of 380 nm or less. When the ultraviolet light emitting diode is a vertical light emitting diode, a heavily doped n-type gallium nitride (GaN) or n-type indium gallium nitride (InGaN) / n-type gallium nitride (GaN) used in blue and green light emitting diodes is used. Superlattice current spreading layers cannot be used. In this case, n is a high concentration of n-type impurities such as silicon, where n is n <-> AlxGa (1-x) N, where 0 <x≤1, or x is n-type AlxGa (1-x) N, where 0 <x <1. The / n-type AlN superlattice layer is used as the current spreading layer 80. Also, aluminum nitride (AlN) or aluminum gallium nitride (AlGaN) is used as the active layer 40 instead of gallium nitride (GaN), and n-type aluminum gallium nitride (AlGaN) 100 is used instead of n-type gallium nitride (GaN). do. Since the p-type semiconductor layer 50, the metal layer 90, the n-electrode 70, and the p-electrode 60 are the same as those of the other embodiment, a description thereof will be omitted. When the light emitting diode wafer is grown with such a material, an epi wafer as shown in FIG. 4 can be grown.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and various changes and modifications can be made by those skilled in the art within the scope of the claims. It is self-evident.

As described above, the present invention can improve the luminous efficiency of the light emitting diode by inserting a current diffusion layer between the n-electrode and the n-type semiconductor layer in manufacturing the light emitting diode. In addition, even when a high current is to be applied, since the current is sufficiently diffused in the current diffusion layer rather than the shortest distance between the n-electrode and the opposite metal, the problem of deterioration of the characteristics of the device during high current injection is reduced. Therefore, reliability and luminous efficiency may be improved when manufacturing a large area light emitting diode for illumination.

Claims (16)

In the nitride compound light emitting diode, An active layer; A p-type semiconductor layer formed on one side of the active layer; A p-electrode formed on one side of the p-type semiconductor layer; An n-type semiconductor layer formed on the other side of the active layer; A current diffusion layer formed on one side of the n-type semiconductor layer; An n-electrode formed on one side of the current spreading layer, The current diffusion layer includes a gallium nitride (GaN) layer doped with a high concentration of silicon, an indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer, or a silicon gallium nitride (SiGaN) layer. delete The method according to claim 1, The current diffusion layer uses a silane (SiH ₄ ), disilane (Si ₂ H ₆ ) or tetraethoxysilane, characterized in that the light emitting diode. The method according to claim 1 or 3, The high concentration silicon-doped gallium nitride (GaN) layer is characterized by forming a gallium nitride (GaN) layer having a silicon doping level of 1 × 10 ²⁰ ~ 1 × 10 ²² cm ^-3 to a thickness of 30 ~ 10㎛ Light emitting diode. The method according to claim 1 or 3, The indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer is a light emitting diode using trimethyl indium and triethyl indium as an indium source. The method according to claim 5, The indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer forms a growth thickness of n-type indium gallium nitride (InGaN) and n-type gallium nitride (GaN) in 1 to 30 pairs, respectively, at 10 to 1000 Å. Light emitting diodes, characterized in that. The method according to claim 1 or 3, The silicon gallium nitride (SiGaN) layer is a light emitting diode, characterized in that formed to a thickness of 30 ~ 2㎛. The method according to claim 1, The current diffusion layer A superlattice layer of heavily doped n-type Al x Ga (1-x) N or n-type Al x Ga (1-y) N and n-type aluminum nitride (AlN); X is 0 <x≤1; And y is 0 <y <1. The method according to claim 1, A light emitting diode comprising a metal layer formed between a p-type semiconductor layer and a p-electrode. The method according to claim 9, The metal layer comprises a nickel (Ni) / gold (Au) or silver (Ag) or copper (Cu). The method according to claim 1, The n-electrode includes at least one of nickel (Ni), aluminum (Al), titanium (Ti), gold (Au), and indium tin oxide (ITO). In the nitride compound light emitting diode, Sequentially forming a current spreading layer, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the substrate; Removing the substrate; Forming an n-electrode and a p-electrode on the n-type semiconductor layer and the p-type semiconductor layer, respectively; The current diffusion layer includes a gallium nitride (GaN) layer doped with a high concentration of silicon, an indium gallium nitride (InGaN) / gallium nitride (GaN) superlattice current diffusion layer, or a silicon gallium nitride (SiGaN) layer. Manufacturing method. delete delete The method according to claim 12, The high concentration of silicon-doped gallium nitride (GaN) layer is a 30 ~ 10㎛ thickness of gallium nitride (GaN) layer having a silicon doping level of 1 × 10 ²⁰ ~ 1 × 10 ²² cm ^-3 at 700 ~ 1200 degrees Celsius Method for manufacturing a light emitting diode, characterized in that formed. The method according to claim 12, The silicon gallium nitride (SiGaN) layer is a method of manufacturing a light emitting diode, characterized in that formed in a thickness of 30 ~ 2㎛ at 700 ~ 1200 degrees Celsius.

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