KR100803247B1 - Nitride semiconductor light emitting diode - Google Patents

Abstract

A nitride semiconductor light emitting diode is provided to achieve high brightness by forming two active layers outputting a light with the same wavelength in one LED. A first n-type nitride semiconductor layer(120a) is formed on a substrate(110). At least two nitride semiconductor layers having different energy band are deposited on a predetermined portion of the n-type nitride semiconductor layer to form a current diffusion layer. A first active layer(130a) is formed on the current diffusion layer, and a p-type nitride semiconductor layer(140) is formed on the first active layer. A second active layer(130b) is formed on the p-type nitride semiconductor layer. A first n-type electrode(160a) is formed on the first n-type nitride semiconductor layer without the first active current diffusion layer, and a p-type electrode(170) is formed on the p-type nitride semiconductor layer without the second active layer. A second n-type nitride semiconductor layer(120b) is formed on the second active layer, and a second n-type electrode(160b) is formed on the second n-type nitride semiconductor layer.

Description

Nitride semiconductor light emitting diodes {NITRIDE SEMICONDUCTOR LIGHT EMITTING DIODE}

1 is a perspective view showing the structure of a nitride-based semiconductor light emitting diode according to the prior art.

FIG. 2 is a cross-sectional view taken along line II-II ′ of FIG. 1. FIG.

3 is a perspective view showing the structure of a nitride-based semiconductor light emitting diode according to a first embodiment of the present invention.

4 is a cross-sectional view taken along line IV-IV ′ of FIG. 3.

5 is a sectional view showing a second embodiment of a nitride based semiconductor light emitting diode according to the present invention;

6 is a sectional view showing a third embodiment of a nitride based semiconductor light emitting diode according to the present invention;

7 is a sectional view showing a fourth embodiment of a nitride based semiconductor light emitting diode according to the present invention;

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

110 substrate 120a first n-type nitride semiconductor layer

120b: second n-type nitride semiconductor layer

130a: first active layer 130b: second active layer

140: p-type nitride semiconductor layer

160a: first n-type electrode 160b: second n-type electrode

170: p-type electrode 200: current diffusion layer

300: current blocking layer

The present invention relates to a nitride-based semiconductor light emitting device, and more particularly to a nitride-based semiconductor light emitting diode that can implement high brightness or output light of different wavelengths at the same time.

In general, a light emitting diode (hereinafter referred to as 'LED') constitutes a light emitting source by changing compound semiconductor materials such as GaAs, AlGaAs, GaN, InGaN, and AlGaInP. It refers to a semiconductor light emitting device that can implement light.

In recent years, due to the rapid development of semiconductor technology, LED has escaped from general-purpose products of low brightness, and various researches have recently been conducted to produce high brightness and high quality products.

Next, a nitride based semiconductor LED according to the prior art will be described in detail with reference to FIGS. 1 and 2.

1 is a perspective view illustrating a structure of a nitride semiconductor light emitting diode according to the prior art, and FIG. 2 is a cross-sectional view taken along line II-II ′ of FIG. 1.

As shown, the nitride-based semiconductor LED according to the prior art is an n-type nitride semiconductor layer 120, a multi-well structure GaN / InGaN active layer 130 and a p-type nitride semiconductor layer sequentially formed on the sapphire substrate 110 A portion of the p-type nitride semiconductor layer 140 and the GaN / InGaN active layer 130 is removed by a partial etching process, the n-type nitride semiconductor layer 120 Some of the upper surface of the structure is exposed.

An n-type electrode 160 is formed on the n-type nitride semiconductor layer 120, and a transparent electrode 150 made of ITO and a p-type electrode 170 are formed on the p-type nitride semiconductor layer 140. .

As described above, the nitride-based semiconductor LED according to the prior art is transparent to reduce the absorption of light emitted from the active layer 130 by increasing the current diffusion effect on the light emitting surface, that is, p-type nitride semiconductor layer 140 The electrode 150 is formed.

However, the transparent electrode 150 as described above could increase the current diffusion effect of the p-type nitride semiconductor layer 140 to partially increase the overall luminance, but there is a limit in obtaining higher luminance.

Therefore, there is a continuous demand for development of a nitride-based semiconductor LED related technology capable of realizing high brightness.

Accordingly, an object of the present invention is to provide a nitride-based semiconductor LED that can implement high brightness by having two active layers in one LED in order to solve the above problems.

In order to achieve the above object, the present invention provides a first n-type nitride semiconductor layer formed on a substrate, a first active layer formed in a predetermined region on the first n-type nitride semiconductor layer, and p formed on the first active layer A type nitride semiconductor layer, a second active layer formed in a predetermined region on the p-type nitride semiconductor layer, a first n-type electrode formed on a first n-type nitride semiconductor layer on which the first active layer is not formed, and the second A p-type electrode formed on the p-type nitride semiconductor layer on which the active layer is not formed, a second n-type nitride semiconductor layer formed on the second active layer, and a second n-type electrode formed on the second n-type nitride semiconductor layer It provides a nitride-based semiconductor light emitting diode comprising.

In the nitride-based semiconductor light emitting diode of the present invention, it is preferable to further include a transparent electrode formed on the second n-type nitride semiconductor layer.

In the nitride-based semiconductor light emitting diode of the present invention, a current formed at an interface between the first n-type nitride semiconductor layer and the first active layer or at an interface between the second n-type nitride semiconductor layer and the first active layer. It is preferable to further include a diffusion layer. The current spreading layer may be formed in a multilayer structure in which two or more nitride semiconductor layers having different energy bands are stacked, or in a multilayer structure in which two or more nitride semiconductor layers doped with different types of conductive impurities are stacked. Can be formed. At this time, the nitride semiconducting layer is preferably composed of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition.

The nitride-based semiconductor LED of the present invention may further include a current blocking layer formed at an interface between the first active layer and the p-type nitride semiconductor layer or at an interface between the p-type nitride semiconductor layer and the second active layer. It is desirable to. The current blocking layer may have a multilayer structure in which two or more nitride semiconductor layers having different energy bands are stacked, or a multilayer structure in which two or more nitride semiconductor layers doped with conductive impurities of different concentrations are stacked. It can be formed as. At this time, the nitride semiconductor layer is preferably made of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition.

In the nitride-based semiconductor light emitting diode of the present invention, the first n-type electrode, the p-type electrode, and the second n-type electrode are preferably formed of a metal electrode or a transparent electrode.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like parts throughout the specification.

A nitride based semiconductor light emitting diode according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

Example  One

First, a nitride based semiconductor light emitting diode according to a first embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

3 is a perspective view illustrating a structure of a nitride semiconductor light emitting diode according to a first exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line IV-IV ′ of FIG. 3.

As illustrated, the nitride semiconductor light emitting diode according to the first embodiment of the present invention includes a buffer layer (not shown) formed on the substrate 110 and a first n-type nitride semiconductor layer (not shown) on the buffer layer. 120a), the p-type nitride semiconductor layer 140 using the first light emitting structure and the p-type nitride semiconductor layer 140 in which the first active layer 130a and the p-type nitride semiconductor layer 140 are sequentially stacked in common. ) Is formed of a second light emitting structure in which a second active layer 130b and a second n-type nitride semiconductor layer 120b are sequentially stacked. In this case, the first light emitting structure and the second light emitting structure are formed in a reverse order of the nitride semiconductor layers stacked in order to use the p-type nitride semiconductor layer 140 in common.

The substrate 110 is preferably formed using a transparent material including sapphire. In addition to sapphire, the substrate 110 may be formed of zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (SiC), and aluminum nitride (AlN).

The buffer layer (not shown) is a layer for improving lattice matching with the substrate 110 including the sapphire before growing the first n-type nitride semiconductor layer 120a on the substrate 110. In general, AlN / GaN is formed. This is a layer for improving lattice matching with the substrate 110 and is not necessarily a layer, and may be omitted depending on the characteristics of the device and the process conditions.

The first and second n-type or p-type nitride semiconductor layers 120a, 120b, and 140 are formed of GaN layers or GaN / AlGaN layers doped with each conductive type impurity.

Although not shown, surface irregularities may be formed on the surface of the p-type nitride semiconductor layer 140 in order to increase light extraction efficiency. Thus, when surface irregularities are formed, the present invention may be grown thereon. Due to the second active layer 130b, it is possible to naturally implement a non-polar LED.

In addition, the first and second active layers 130a and 130b are formed of a multi-well structure composed of InGaN / GaN layers.

In this case, the first and second active layers 130a and 130b may be formed as one quantum well layer or a double hetero structure, and the first and second active layers 130a and 130b may be formed of indium (In). ) Determines whether the diode is a green light emitting device or a blue light emitting device. More specifically, about 22% of indium is used for light emitting devices having blue light, and about 40% of indium is used for light emitting devices having green light.

That is, the first and second active layers 130a and 130b according to the present invention may implement high brightness by outputting light having the same wavelength as the amount of indium used to form them.

In particular, the first and second active layer 130a, 130b according to the present invention by controlling the amount of indium used to form them differently by simultaneously outputting different wavelength light, for example blue or green wavelength light, One LED can realize two colors at the same time.

A portion of the second n-type nitride semiconductor layer 120b and the second active layer 130b are removed by first mesa etching to expose a portion of the p-type nitride semiconductor layer 140 on the bottom surface thereof. The exposed portion of the p-type nitride semiconductor layer 140 and the first active layer 130a are removed by the second mesa etching to expose a portion of the first n-type nitride semiconductor layer 120a on the bottom.

A first n-type electrode 160a is formed on a predetermined portion of the first n-type nitride semiconductor layer 120a exposed by the second mesa etching, and a predetermined portion of the second n-type nitride semiconductor layer 120b is formed. The second n-type electrode 160b is formed in the portion. The first and second n-type electrodes 160a and 160b may be formed of a metal electrode such as Cr / Au or a transparent electrode such as TCO.

The p-type electrode 170 is formed on a predetermined portion of the p-type nitride semiconductor layer 140 exposed by the first mesa etching. Here, like the first and second n-type electrodes 160a and 160b, the p-type electrode 170 may be formed of a metal electrode such as Cr / Au or a transparent electrode such as TCO. In this case, the p-type electrode 170 is used as a common electrode between the first n-type electrode 160a formed in the first light emitting structure and the second n-type electrode 160b formed in the second light emitting structure.

Example  2

Referring to FIG. 5, a second embodiment of the present invention will be described. However, the description of the same parts as those of the first embodiment of the configuration of the second embodiment will be omitted, and only the configuration that is different from the second embodiment will be described in detail.

5 is a cross-sectional view showing a second embodiment of a nitride based semiconductor light emitting diode according to the present invention.

As shown, the nitride-based semiconductor LED according to the second embodiment has the same configuration as most of the nitride-based semiconductor LED according to the first embodiment, except that the current is on the second n-type nitride semiconductor layer 120b. It differs from the first embodiment only in that a transparent electrode 150 for increasing the diffusion effect is further formed.

Here, the transparent electrode 150 may be formed not only of a conductive metal oxide such as indium tin oxide (ITO) but also a metal thin film having high conductivity and low contact resistance if the transmittance of the LED is high.

Therefore, the second embodiment also includes the first and second active layers 130a and 130b for outputting light of different wavelengths or light of the same wavelength as in the first embodiment, and thus the same as in the first embodiment. Actions and effects can be obtained.

In addition, in the second embodiment, unlike the conventional transparent electrode formed on the surface of the p-type nitride semiconductor layer (see reference numeral '150' in FIG. 2), the transparent electrode 150 is formed on the surface of the second n-type nitride semiconductor layer 120b. ), More stable contact resistance can be realized.

This is well known to those skilled in the art, it can be seen that the n-type nitride semiconductor is excellent in the implementation of a transparent electrode made of a conductive metal oxide such as ITO compared to the p-type nitride semiconductor.

Example  3

Referring to FIG. 6, a third embodiment of the present invention will be described. However, since the third embodiment also has the same configuration as most of the first embodiment, only a configuration different from the first embodiment will be described below.

6 is a cross-sectional view showing a third embodiment of a nitride based semiconductor light emitting diode according to the present invention.

As shown, the nitride semiconductor LED according to the third embodiment also includes the first and second active layers 130a and 130b for outputting light of different wavelengths or light of the same wavelength. The first embodiment has the same configuration as the first embodiment, except that the current diffusion layer 200 is formed at the interface between the first active layer 130a and the first n-type nitride semiconductor layer 120a. Have a different configuration.

Therefore, even with this third embodiment, the same operation and effect as in the first and second embodiments can be obtained.

As described above, the current spreading layer 200 according to the third embodiment increases the current spreading effect to contact the first n-type nitride semiconductor layer 120a having the high energy band with the first n-type electrode 160a. Therefore, it minimizes the increase in operating voltage from increasing contact resistance.

Here, the current spreading layer 200 may be formed in a multilayer structure in which two or more nitride semiconductor layers having different energy bands are stacked, or two or more nitride semiconductor layers doped with different types of conductive impurities are stacked. It may be formed in a multilayer structure. At this time, the nitride semiconducting layer is preferably composed of In _X Al _Y Ga _{1 -XY} N (0≤X, 0≤Y, X + Y≤1) composition.

Although not shown, the current diffusion layer 200 may also form an interface between the second active layer 130b and the second n-type nitride semiconductor layer 120b.

In addition, the current diffusion layer 200 is also applicable to the second embodiment.

Example  4

Referring to FIG. 7, a fourth embodiment of the present invention will be described. However, since the fourth embodiment also has the same configuration as most of the first embodiment, only a configuration different from the first embodiment will be described below.

7 is a cross-sectional view showing a fourth embodiment of a nitride-based semiconductor light emitting diode according to the present invention.

As illustrated, the nitride semiconductor LED according to the fourth embodiment also includes the first and second active layers 130a and 130b for outputting light of different wavelengths or light of the same wavelength. It has the same configuration as in the first embodiment, except that the current blocking layer 300 is formed at the interface between the p-type nitride semiconductor layer 140 in contact with the first and second active layers 130a and 130b. It has a configuration different from that of the first embodiment described above.

Therefore, even with this third embodiment, the same operation and effect as in the first and second embodiments can be obtained.

In the present embodiment, the first current blocking layer 300 is formed at the interface between the p-type nitride semiconductor layer 140 in contact with the first and second active layers 130a and 130b. 300a) and the second current blocking layer 300b are illustrated, but the present invention is not limited thereto, and only the one interface between the first active layer 130a or the second active layer 130b depends on the characteristics and process conditions of the LED. It is possible to form.

The current blocking layer 300 may be formed in a multilayer structure in which two or more nitride semiconductor layers having different energy bands are stacked, or two or more nitride semiconductor layers doped with conductive impurities of different concentrations. It may be formed in a multilayer structure that is stacked. In this case, the nitride semiconductor layer is preferably composed of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition, n-type conductivity impurity or p-type conductivity It is preferable to form by varying the doping concentration of the type impurities.

The current blocking layer 300 is also applicable to the second and third embodiments.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

As described above, the present invention may provide a nitride-based semiconductor LED capable of realizing high brightness by providing two active layers that output light having the same wavelength to each other in one LED.

In addition, the present invention includes two active layers for outputting light of different wavelengths in one LED so that two colors can be simultaneously implemented with one LED.

In addition, the present invention provides a transparent electrode on the n-type nitride semiconductor layer to improve the current diffusion effect and at the same time implement a more stable contact resistance.

Therefore, the present invention has the effect of improving the luminance characteristics and reliability of the nitride-based semiconductor LED.

Claims (18)

A first n-type nitride semiconductor layer formed on the substrate; A current diffusion layer formed in a predetermined region on the first n-type nitride semiconductor layer and having a multilayer structure in which two or more layers of nitride semiconductor layers having different energy bands are stacked; A first active layer formed on the current spreading layer; A p-type nitride semiconductor layer formed on the first active layer; A second active layer formed in a predetermined region on the p-type nitride semiconductor layer; A first n-type electrode formed on the first n-type nitride semiconductor layer on which the first active layer is not formed; A p-type electrode formed on the p-type nitride semiconductor layer on which the second active layer is not formed; A second n-type nitride semiconductor layer formed on the second active layer; And A second n-type electrode formed on the second n-type nitride semiconductor layer; Nitride-based semiconductor light emitting diode comprising a. The method of claim 1, The nitride-based semiconductor light emitting diode further comprises a transparent electrode formed on the second n-type nitride semiconductor layer. delete delete The method of claim 1, The nitride semiconductor layer having different energy bands constituting the current spreading layer is composed of In _X Al _Y Ga _1-XY N (0≤X, 0≤Y, X + Y≤1) composition, and Al and In A nitride-based semiconductor light emitting diode, characterized in that formed by varying the composition ratio. The method of claim 1, The current diffusion layer is a nitride-based semiconductor light emitting diode, characterized in that formed of a multilayer structure in which two or more layers of nitride semiconductor layers doped with conductive impurities of different types are stacked. The method of claim 6, The nitride semiconductor layer doped with conductive impurities of different types constituting the current spreading layer is composed of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition. And a doping concentration between the n-type conductivity and the p-type conductivity impurity. The method of claim 1, And a current spreading layer formed at an interface between the second n-type nitride semiconductor layer and the second active layer. The method of claim 8, The current diffusion layer is a nitride-based semiconductor light emitting diode, characterized in that formed in a multi-layer structure in which two or more layers of nitride semiconductor layers having different energy bands are stacked. The method of claim 9, The nitride semiconductor layer having different energy bands constituting the current spreading layer is composed of In _X Al _Y Ga ₁ -X _{- Y} N (0≤X, 0≤Y, X + Y≤1) composition, and A nitride-based semiconductor light emitting diode formed by varying the composition ratio of In. The method of claim 9, The current diffusion layer is a nitride-based semiconductor light emitting diode, characterized in that formed of a multilayer structure in which two or more layers of nitride semiconductor layers doped with conductive impurities of different types are stacked. The method of claim 11, The nitride semiconductor layer doped with conductive impurities of different types constituting the current spreading layer is composed of an In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition. And a dopant concentration of an n-type conductivity and a p-type conductivity impurity. A first n-type nitride semiconductor layer formed on the substrate; A first active layer formed in a predetermined region on the first n-type nitride semiconductor layer; A p-type nitride semiconductor layer formed on the first active layer; A second active layer formed in a predetermined region on the p-type nitride semiconductor layer; A first n-type electrode formed on the first n-type nitride semiconductor layer on which the first active layer is not formed; A p-type electrode formed on the p-type nitride semiconductor layer on which the second active layer is not formed; A second n-type nitride semiconductor layer formed on the second active layer; And A second n-type electrode formed on the second n-type nitride semiconductor layer; At least two layers of nitride semiconductor layers having different energy bands are laminated at an interface between the first active layer and the p-type nitride semiconductor layer or at an interface between the p-type nitride semiconductor layer and the second active layer. The nitride-based semiconductor light emitting diode further comprises a current blocking layer formed of a multi-layer structure. delete The method of claim 13, The nitride semiconductor layer having different energy bands constituting the current blocking layer is composed of In _X Al _Y Ga _1-XY N (0 ≦ X, 0 ≦ Y, X + Y ≦ 1), and Al and In A nitride-based semiconductor light emitting diode, characterized in that formed by varying the composition ratio of. The method of claim 13, The current blocking layer is a nitride-based semiconductor light emitting diode, characterized in that formed of a multilayer structure in which two or more layers of nitride semiconductor layers doped with conductive impurities of different concentrations are stacked. The method of claim 16, The nitride semiconductor layer doped with conductive impurities of different concentrations constituting the current blocking layer is composed of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1). A nitride-based semiconductor light emitting diode, characterized in that formed by varying the doping concentration of the n-type conductivity or p-type conductivity impurities. The method according to claim 1 or 13, And the first n-type electrode, the p-type electrode, and the second n-type electrode are formed of a metal electrode or a transparent electrode.

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