KR20130061155A - Nitride based light emitting diode with excellent effect of blocking leakage current and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A nitride based light emitting diode with excellent leakage current blocking effect and a manufacturing method thereof are provided to improve the light efficiency by forming a current blocking part. CONSTITUTION: A current blocking part(220) is made of an insulating material. The current blocking part is arranged between a substrate and an n-type nitride layer(230). An active layer(240) is formed on the n-type nitride layer. A p-type nitride layer is formed on the active layer. The substrate has an upper surface.

Description

Nitride semiconductor light emitting device having excellent leakage current blocking effect and manufacturing method thereof {NITRIDE BASED LIGHT EMITTING DIODE WITH EXCELLENT EFFECT OF BLOCKING LEAKAGE CURRENT AND MANUFACTURING METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device and a method for manufacturing the same, and more particularly to a nitride semiconductor light emitting device capable of blocking a leakage current and a method for manufacturing the same.

Conventional nitride semiconductor devices include, for example, GaN-based nitride semiconductor devices, which include high-speed switching and high-output devices such as blue and green LED light emitting devices, MESFETs and HEMTs, etc. It is applied to the back.

In particular, blue and green LED light emitting devices have already been mass-produced and global sales are increasing exponentially.

The conventional GaN-based nitride semiconductor light emitting device may be, for example, a nitride semiconductor light emitting device 10 having an active layer 15 having a multi-quantum well structure as shown in FIG. 1. The conventional nitride semiconductor light emitting device includes a sapphire substrate 10, a buffer layer 11, an n-type nitride layer 12, an active layer 13, and a p-type nitride layer 14. The p-side electrode 15 is formed on the upper surface of the p-type nitride layer 14, and the n-side electrode 16 is sequentially formed on the exposed surface of the n-type nitride semiconductor layer 12.

However, the nitride semiconductor light emitting device injects electrons and holes into the active layer 13 and emits light by the combination of the electrons and holes. In order to improve the light emitting efficiency of the active layer 13, the light extraction efficiency, that is, the internal quantum Research has been actively conducted in terms of improving efficiency and external quantum efficiency.

In general, the improvement related to the internal quantum efficiency is a way to increase the light efficiency generated from the active layer 13 primitive, as described in Korean Patent Publication No. 2010-0037433 (2010.04.09) There is an interest in improving crystal quality.

Specifically, the leakage current between the n-type nitride semiconductor layer 12 and the buffer layer 11 of the nitride semiconductor light emitting device due to uneven current spreading due to the large area of the nitride semiconductor light emitting device is increased. The problem is that the path increases.

Therefore, the large-area nitride semiconductor light emitting device has a low current density with respect to the active layer 13, resulting in a problem that the internal quantum efficiency is lowered.

SUMMARY OF THE INVENTION An object of the present invention is to provide a nitride semiconductor light emitting device having improved luminous efficiency by preventing leakage current.

Another object of the present invention is to provide a method for producing a nitride semiconductor light emitting device having the above object.

The nitride semiconductor light emitting device of the present invention for achieving the above object comprises a current blocking portion formed between the substrate and the n-type nitride layer; An active layer formed on an upper surface of the n-type nitride layer; And a p-type nitride layer formed on an upper surface of the active layer, wherein the current blocking unit is formed of an insulating material.

In the nitride semiconductor light emitting device of the present invention, the current blocking unit includes at least one of an oxide layer, an undoped nitride layer, an oxide layer containing at least one of Ti, Fe, and Cr current blocking impurities, and the current blocking impurities. It characterized in that it comprises a nitride layer containing and at least one layer selected from the nitride layer adjusted the Al content.

In the nitride semiconductor light emitting device of the present invention, the current blocking unit is a nitride layer in which the Al content is adjusted, for example, an AlGaN layer in which the Al content is adjusted, and the Al content is 10 to 40% by weight with respect to the entire AlGaN layer. It has a thickness range of 0.02㎛ ~ 0.5㎛.

In the nitride semiconductor light emitting device of the present invention, the current blocking unit is an AlGaN layer having an Al content adjusted, and a product of the Al content (atomic ratio) and the layer thickness (μm) is 0.01 to 0.06.

In the nitride semiconductor light emitting device of the present invention, the current blocking unit includes: a first current blocking layer formed in the substrate direction; A second current blocking layer formed on an upper surface of the first current blocking layer; And a third current blocking layer formed on an upper surface of the second current blocking layer, wherein the first current blocking layer has an AlGaN layer containing an n-type dopant with an Al content adjusted. n-AlGaN layer, the second current blocking layer is an AlGaN layer containing a p-type dopant with adjusting Al content p-AlGaN layer, the third current blocking layer is an Al content with an n-type dopant It is characterized in that the AlGaN layer is an n-AlGaN layer.

A method of manufacturing a nitride semiconductor light emitting device according to the present invention includes forming a current blocking portion between a substrate and an n-type nitride layer; Forming an active layer on the n-type nitride layer; And forming a p-type nitride layer on the active layer, wherein the current blocking unit is formed of an insulating material.

In the method of manufacturing a nitride semiconductor light emitting device according to the present invention, the forming of the current blocking unit further includes forming a buffer layer between the substrate and the n-type nitride layer, wherein the current blocking unit is an upper surface of the buffer layer. And at least one of a lower surface of the buffer layer and an inside of the buffer layer.

According to the nitride semiconductor light emitting device of the present invention and a method of manufacturing the same, by using a current blocking layer that performs a function of blocking current, the current flows only into the active layer without leakage to the buffer layer and the substrate, thereby improving luminous efficiency. It works.

1 is a cross-sectional view showing the basic structure of a conventional nitride semiconductor light emitting device.
2 is a cross-sectional view illustrating a nitride semiconductor light emitting device according to an embodiment of the present invention.
3 is a cross-sectional view illustrating a nitride semiconductor light emitting device according to another embodiment of the present invention.
4A to 4E are cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting device according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

As shown in FIG. 2, the nitride semiconductor light emitting device according to the exemplary embodiment of the present invention includes a substrate 100, a buffer layer 110, a current blocking layer 120, an n-type nitride layer 130, and an active layer 140. and a p-type nitride layer 150, a transparent electrode layer 160, a p-side electrode 171, and an n-side electrode 172.

The substrate 100 may be a GaN substrate or a sapphire substrate having an uneven structure formed on an upper surface thereof.

The buffer layer 110 is a layer provided to cover the upper surface of the substrate 100 selectively, and may be formed of AlN or GaN to solve the lattice mismatch between the substrate 100 and the current blocking layer 120. Here, when using a sapphire substrate having a concave-convex structure on the upper surface as the substrate 100, the buffer layer 110 may be formed in a form covering the upper surface of the substrate 100, the concave-convex structure is formed.

The current blocking layer 120 is formed between the buffer layer 110 and the n-type nitride layer 130 and supplies current to the buffer layer 110 and the substrate 100 so that the current flows to the active layer 140 without leakage. Can block function. Here, the current blocking layer 120 may be formed on any one of the upper surface, the lower surface and the inside of the buffer layer 110.

The current blocking layer 120 is an oxide layer, an undoped nitride layer, a layer made of an oxide or nitride containing at least one of current blocking impurities such as Ti, Fe, Cr, or a nitride layer having an Al content adjusted. It can be formed as. Here, the current blocking layer 120 is specifically, an oxide layer such as SiO ₂ , a SiN layer, an undoped GaN layer and an nitride such as InGaN, or Ti, Fe, Cr, etc. It is also possible to form a layer containing an impurity for blocking current, and an AlGaN layer in which the Al content is adjusted.

The thickness of the current blocking layer 120 is determined according to the material of the layer. For example, the thickness of the current blocking layer 120 may be 0.02 μm to 0.5 μm when the layer is made of AlGaN. In this case, when the thickness of the current blocking layer 120 is out of this range and less than 0.02 μm, current blocking may not be performed. When the thickness of the current blocking layer 120 exceeds 0.5 μm, lattice mismatch occurs with the n-type nitride layer 130, resulting in strain defects. Generates.

The n-type nitride layer 130 is a layer provided on the upper surface of the current blocking layer 120. For example, a first layer made of AlGaN doped with Si and a second layer made of GaN of undoped are alternately provided. It may be formed in a laminated structure. Of course, the n-type nitride layer 130 may be grown as a single nitride layer, but may be formed as a stacked structure in which the first layer and the second layer are alternately provided to act as a carrier-limiting layer having good crystallinity without cracks. Can be.

The active layer 140 may be provided as a single layer between the n-type nitride layer 130 and the p-type nitride layer 150 or a multi-quantum well structure in which a plurality of quantum well layers and quantum barrier layers are alternately stacked. Can be. Here, the active layer 140 is made of a multi-quantum well structure, the quantum barrier layer may be a quaternary nitride layer of AlGaInN containing Al, for example, the quantum well layer may be made of, for example, InGaN. The active layer 140 of such a structure can suppress spontaneous polarization due to stress and deformation generated.

The p-type nitride layer 150 may be formed, for example, in a stacked structure in which a first layer of p-type AlGaN doped with Mg with a p-type dopant is alternated with a second layer made of p-type GaN doped with Mg. . In addition, the p-type nitride layer 150 may act as a carrier limiting layer similarly to the n-type nitride layer 130.

The transparent electrode layer 160 is made of a transparent conductive oxide on the upper surface of the p-type nitride layer 150, and the material includes elements such as In, Sn, Al, Zn, Ga, and the like, for example, ITO, CIO, and ZnO. , NiO, In ₂ O ₃ It may be formed.

Such a nitride semiconductor light emitting device according to an embodiment of the present invention has a current blocking layer 120 between the buffer layer 110 and the n-type nitride layer 130, the current by the insulating function of the current blocking layer 120 May flow to the active layer 140 without leaking to the buffer layer 110 and the substrate 100.

Here, the current blocking layer 120 is provided between the buffer layer 110 and the n-type nitride layer 130, but is not limited thereto and the current blocking layer 120 is formed between the substrate 100 and the buffer layer 110 or Or may be formed inside the buffer layer 110.

In order to verify the efficiency of the current blocking layer 120, for example, the current blocking between the buffer layer 110 of 2㎛ thickness and the n-type nitride layer 130 of 4㎛ thickness in a chip of 1200㎛ 600㎛ size The case where the layer 120 is formed of an AlGaN layer in which a predetermined thickness and Al content are adjusted is applied. Here, the Al content of the current blocking layer 120 preferably has a range of 10 to 40% by weight based on the entire current blocking layer 120.

Specifically, for each case in which the Al content and thickness of the current blocking layer 120 were adjusted as described in [Table 1], the ratio at which the voltage measured by applying a current of 1 mA was detected to be 2.1 V or more ( %), I.e. yield of 1㎂Vf.

As a result, it can be seen that the yield of 1 mA Vf is improved in the product of Al content and thickness in the range of 0.01 to 0.06, thereby increasing the low current yield.

[Table 1]

This characteristic may be regarded as a result of the current blocking layer 120 performing a function of blocking current so that the current flows only into the active layer 140 without leaking to the buffer layer 110 and the substrate 100.

Hereinafter, a nitride semiconductor light emitting device according to another embodiment of the present invention will be described with reference to FIG. 3. Here, in the case where it is determined that the detailed description of the related known structure or function of the nitride semiconductor light emitting device may obscure the gist of the present invention, the detailed description thereof will be omitted.

As shown in FIG. 3, the nitride semiconductor light emitting device according to another exemplary embodiment of the present invention includes a substrate 200, a buffer layer 210, a current blocking unit 220 formed of a stacked structure of at least three layers, and an n-type nitride layer. 230, an active layer 240, a p-type nitride layer 250, a transparent electrode layer 260, a p-side Z electrode 271 and an n-side electrode 272.

The current blocking unit 220 may include a first current blocking layer 221, a second current blocking layer 222, and a third current blocking layer 223 sequentially formed on an upper surface of the buffer layer 210. .

Each of the current blocking layers 221, 222, and 223 of the current blocking unit 220 includes an oxide layer, a nitride layer, a layer made of an oxide or nitride containing at least one impurity for current blocking such as Ti, Fe, Cr, and the Al content. It may be formed of any one selected of one AlGaN layer.

For example, each of the current blocking layers 221, 222, and 223 is formed by selecting any one of the above layers, and the first current blocking layer 221 is an oxide layer of SiO ₂ and a second current blocking layer 222. The nitride layer of silver undoped GaN and the third current blocking layer 223 may be formed of an AlGaN layer in which the Al content is adjusted.

Here, each of the first current blocking layer 221 to the third current blocking layer 223 is differently contained in the Al content in the range of 10 to 40% by weight based on the entire current blocking unit 220, respectively, the n-type dopant or The nitride layer having a p-type dopant may be formed of an npn multilayer structure of an AlGaN layer containing an n-type dopant / AlGaN layer containing an p-type dopant / AlGaN layer containing an n-type dopant.

Of course, each of the first current blocking layer 221 to the third current blocking layer 223 may be preferably formed such that the product of Al content and thickness is in the range of 0.01 to 0.06.

In this case, the n-type dopant of the first current blocking layer 221 and the third current blocking layer 223 is contained at a higher concentration than the p-type dopant concentration of the second current blocking layer 222.

The nitride semiconductor light emitting device according to another embodiment of the present invention applies an npn nitride stacked structure containing an n-type dopant or a p-type dopant from the first current blocking layer 221 to the third current blocking layer 223. .

Therefore, the nitride semiconductor light emitting device according to another embodiment of the present invention is a p-type dopant under the influence of the n-AlGaN layer (221, 223) containing a high concentration n-type dopant up and down in the current blocking unit 220 having an npn structure A junction region of the p-AlGaN layer 222 containing ions is formed as a depletion region so that the current is blocked, thereby completely blocking the current leaking into the buffer layer 210 and the substrate 200.

Hereinafter, a method of manufacturing a nitride semiconductor light emitting device according to another embodiment of the present invention will be specifically described with reference to FIGS. 4A to 4E. Here, the method of manufacturing a nitride semiconductor light emitting device according to another embodiment of the present invention is an npn nitride stacked structure containing an n-type dopant or a p-type dopant from the first current blocking layer 221 to the third current blocking layer 223 It will be described by applying the current blocking unit 220.

In order to manufacture a nitride semiconductor light emitting device according to another embodiment of the present invention, as shown in FIG. 4A, a buffer layer 210 and a first current blocking layer 221 are sequentially formed on an upper surface of the substrate 200. . Here, the substrate 200 may be a GaN substrate or a sapphire substrate having an uneven structure formed on an upper surface thereof.

Of course, before the buffer layer 210 and the first current blocking layer 221 are sequentially formed on the upper surface of the substrate 200, a concave-convex structure is formed on the upper surface by using a sapphire substrate as the substrate 200. can do.

The buffer layer 210 may be selectively formed on the upper surface of the substrate 200 using a material such as AlN or GaN to eliminate the lattice mismatch between the substrate 110 and the first current blocking layer 221. Here, when using a sapphire substrate having a concave-convex structure on the upper surface as the substrate 200, the buffer layer 210 may be formed in a form covering the upper surface of the substrate 200, the concave-convex structure is formed.

After the buffer layer 210 is formed, a first current blocking layer 221 is formed on the top surface of the buffer layer 210. The first current blocking layer 221 is an oxide layer, an undoped nitride layer, a layer made of an oxide or nitride containing at least one impurity for current blocking, such as Ti, Fe, Cr, and nitride with an adjusted Al content. It may be formed of any one selected from the layers. Here, the nitride layer in which the Al content is adjusted may be an AlGaN layer in which the Al content is adjusted.

Specifically, the first current blocking layer 221 is any one selected from atomic layer epitaxy (ALE), atmospheric pressure chemical vapor deposition (APCVD), metal organic chemical vapor deposition (MOCVD), and plasma enhanced chemical vapor deposition (PECVD). It is possible to form an n-AlGaN layer in which the Al content is adjusted by the vapor phase epitaxy growth method. Of course, the first current blocking layer 221 may be formed of an n-AlGaN layer in which an n-type dopant is implanted by an ion implantation method after forming an AlGaN layer in which an Al content is adjusted by a vapor phase epitaxy growth method.

At this time, the first current blocking layer 221 is formed of an n-AlGaN layer, Al content may be adjusted to be formed within the range of 10 to 40% by weight based on the entire first current blocking layer 221. Preferably, the first current blocking layer 221 may be formed so that the product of Al content and thickness is in the range of 0.01 to 0.06.

After the first current blocking layer 221 is formed, as shown in FIG. 4B, a second current blocking layer 222 of the p-AlGaN layer is formed on the upper surface of the first current blocking layer 221. The second current blocking layer 222 is an oxide layer, an undoped nitride layer, a layer made of an oxide or nitride containing at least one impurity for current blocking, such as Ti, Fe, Cr, and the Al content of the second current blocking layer ( 222) can be formed of any one selected from the layer consisting of AlGaN adjusted in the range of 10 to 40% by weight based on the total.

Here, the second current blocking layer 222 is preferably a gaseous epitaxy growth method selected from ALE, APCVD, and PECVD, similarly to the first current blocking layer 221. It may be formed of a p-AlGaN layer having a range.

After the second current blocking layer 222 is formed, a third current blocking layer 223 of the n-AlGaN layer is formed on the top surface of the second current blocking layer 222 as shown in FIG. 4C. The third current blocking layer 223 is formed of an oxide or nitride containing at least one impurity for current blocking, such as an oxide layer, an undoped nitride layer, Ti, Fe, or Cr, similarly to the first current blocking layer 221. , And Al content in which the Al content is adjusted within the range of 10 to 40 wt% with respect to the entire third current blocking layer 223.

Here, the third current blocking layer 223 may be formed of an n-AlGaN layer having a product of Al content and thickness of 0.01 to 0.06 by the vapor phase epitaxy growth method, similarly to the method of forming the first current blocking layer 221. .

As described above, after the current blocking unit 220 including the first current blocking layer 221 to the third current blocking layer 223 is formed, as shown in FIG. 4D, the n-type nitride layer 230 has a third current. The upper surface of the blocking layer 223 is formed. Here, although the current blocking unit 220 is formed on the upper surface of the buffer layer 210, the current blocking unit 220 may be formed on any one of the upper surface, the lower surface and the inside of the buffer layer 210.

For example, the n-type nitride layer 230 may be formed by supplying a silane gas including an n-type dopant such as NH ₃ , trimetalgallium (TMG), and Si to convert the n-GaN layer into an n-type nitride layer 230. To grow).

After the n-type nitride layer 230 is formed, the active layer 240 is grown on the top surface of the n-type nitride layer 230. The active layer 240 may be formed in a single quantum well structure or a multi-quantum well structure in which a plurality of quantum well layers and a quantum barrier layer are alternately stacked. The active layer 240 according to another embodiment of the present invention may include a quantum well layer and a quantum well layer. A multi-quantum well structure in which a plurality of quantum barrier layers are alternately stacked is applied.

For example, the quantum barrier layer of the active layer 240 is, for example, a quaternary nitride layer of AlGaInN containing Al, and the quantum well layer is formed of, for example, a multi-quantum well structure in which a plurality of InGaN layers are stacked. It is formed to suppress.

After the active layer 240 is formed as described above, the p-type nitride layer 250 and the transparent electrode layer 260 are sequentially formed in the upper surface direction of the active layer 240 similarly to the general nitride semiconductor light emitting device.

After forming the transparent electrode layer 260, as shown in FIG. 4E, lithography etching and cleaning are performed from one region of the transparent electrode layer 260 to a part of the n-type nitride layer 230, thereby cleaning the n-type nitride layer ( Some areas of 230 may be exposed.

After exposing a portion of the n-type nitride layer 230, the p-side electrode 271 and the n-side electrode 2 may be formed on the upper surface of the transparent electrode layer 260 and each of the exposed portions of the n-type nitride layer 230. 272).

Such a method of manufacturing a nitride semiconductor light emitting device according to another embodiment of the present invention includes an AlGaN layer / p-type dopant containing an n-type dopant from the first current blocking layer 221 to the third current blocking layer 223. Although a method of forming a current blocking portion 220 of an npn nitride stacked structure of an AlGaN layer containing an AlGaN layer / n-type dopant is described, the current blocking portion 220 is not limited thereto and is formed of a laminated structure of three or more layers. May be

Therefore, in the method of manufacturing the nitride semiconductor light emitting device according to another embodiment of the present invention, the current is leaked to the buffer layer 210 and the substrate 200 by using the current blocking unit 220 having a laminated structure of three or more layers. A nitride semiconductor light emitting device that can be prevented can be provided.

Although the technical idea of the present invention has been specifically described according to the above preferred embodiments, it is to be noted that the above-described embodiments are intended to be illustrative and not restrictive.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

100, 200: substrate 110, 210: buffer layer
120: current blocking layer 130, 230: n-type nitride layer
140, 240: active layer 150, 250: p-type nitride layer
160 and 260: transparent electrode layers 171 and 271: p-side electrode
172, 272: n-side electrode 220: current interruption
221: first current blocking layer 222: second current blocking layer
223: third current blocking layer

Claims (7)

A current blocking part formed of an insulating material between the substrate and the n-type nitride layer;
An active layer formed on the n-type nitride layer; And
A p-type nitride layer formed on the active layer,
The current blocking unit is a nitride semiconductor light emitting device, characterized in that formed by AlGaN layer of the product of the Al content (atomic ratio) and the layer thickness (㎛) of 0.01 ~ 0.06.
The method of claim 1,
The substrate has a nitride semiconductor light emitting device, characterized in that the upper surface is formed with an uneven structure.
The method of claim 1,
Further comprising a buffer layer between the substrate and the n-type nitride layer,
The current blocking unit is formed on the upper surface of the buffer layer nitride semiconductor light emitting device.
The method of claim 1,
Further comprising a buffer layer between the substrate and the n-type nitride layer,
The current blocking unit is formed in the buffer layer, characterized in that the nitride semiconductor light emitting device.
The method of claim 1,
Further comprising a buffer layer between the substrate and the n-type nitride layer,
The current blocking unit is formed in the lower portion of the buffer layer nitride semiconductor light emitting device.
Forming a current interruption between the substrate and the n-type nitride layer with an insulating material;
Forming an active layer on the n-type nitride layer; And
Forming a p-type nitride layer on the active layer;
Forming the current blocking unit
A method of manufacturing a nitride semiconductor light emitting device, characterized in that the product of Al content (atomic ratio) and layer thickness (μm) is formed of an AlGaN layer having 0.01 to 0.06.
The method according to claim 6,
Before forming the current interruption,
The method of manufacturing a nitride semiconductor light emitting device further comprising the step of forming a concave-convex structure on the substrate.

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