KR20100027407A - Nitride semiconductor light emitting device - Google Patents

Abstract

PURPOSE: A nitride semiconductor light emitting device is provided to improve a current spreading effect and a stress relaxation effect by arranging a multiple structure of a p-type current spreading layer including nitride semiconductor layers with different energy bands and thicknesses which are stacked on a p-type clad layer. CONSTITUTION: An n-type clad layer(103) is formed on a substrate(101). An active layer(104) is formed on the n-type clad layer. A p-type clad layer(105) is formed on the active layer. A p-type current spreading layer is arranged within the p-type clad layer on which nitride semiconductor layers with different energy bands and thicknesses are stacked. A p-type contact layer(106) is formed on the p-type clad layer.

Description

Nitride Semiconductor Light Emitting Device {NITRIDE SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present invention relates to a nitride semiconductor light emitting device, and more particularly, to a nitride semiconductor light emitting device having a p-type current diffusion layer having a multilayer structure in which nitride semiconductor layers having different energy bands and thicknesses are stacked in a p-type cladding layer. It is about.

Recently, III-V nitride semiconductors such as GaN have been spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their excellent physical and chemical properties. LEDs or LDs using III-V nitride semiconductor materials are widely used in light emitting devices for obtaining light in the blue or green wavelength band, and these light emitting devices are used as light sources of various products such as electronic displays and lighting devices. The III-V nitride semiconductor is generally made of a GaN-based material having a composition formula of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1).

Hereinafter, a conventional nitride semiconductor light emitting device using the III-V nitride semiconductor will be described.

According to the prior art, a light emitting device using a nitride semiconductor has a basic structure in which a GaN buffer layer, an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type contact layer are sequentially stacked on a sapphire substrate, which is a light transmissive substrate.

The nitride semiconductor light emitting device may employ a single hetero quantum well having a single quantum well or a multi quantum well structure having a well layer made of InGaN.

In particular, in the above-mentioned nitride semiconductor light emitting device, the multi-quantum well structure has a large number of mini-bands, has high efficiency, and can emit light even at a small current, thereby improving device characteristics such as higher light emission output than a single quantum well structure. It is expected. This discloses an active layer having a multi-quantum well structure consisting of a barrier layer of undoped GaN and a well layer of undoped InGaN in order to improve luminous efficiency and luminous intensity in Japanese Patent Laid-Open No. 10-135514. In addition, a nitride semiconductor device including a cladding layer having a band gap larger than that of the barrier layer of the active layer is disclosed.

However, when the active layer has a multi-quantum well structure, high luminous efficiency and luminous intensity can be obtained. However, there is a limit in luminous efficiency and luminous intensity, that is, light output, for using a nitride semiconductor element as a light source for illumination or an outdoor display. have. In addition, when the active layer has a multi-quantum well structure, the thickness of the whole active layer is thicker than that of the single quantum well structure, so that the series resistance in the longitudinal direction is high, and in particular, in the case of LED elements, the operating voltage (V _f ). There is a problem of getting higher.

However, as described above, when the operating voltage of the LED device is increased, a blue-shift occurs in which the center wavelength of the LED device is shortened due to the concentration of the current density, thereby reducing the luminous efficiency.

In addition, since the light emitting device using the nitride semiconductor is generally poor in resistance to electrostatic discharge (ESD), it is necessary to improve the electrostatic discharge characteristics. In particular, the nitride semiconductor LED device or LD device has a problem that can be damaged by the static electricity easily generated in people or things in the process of handling or using the same.

Accordingly, in order to suppress damage of the nitride semiconductor device due to ESD, various studies have recently been conducted. For example, US Pat. No. 6,593,597 discloses a technique for protecting an LED device from ESD by integrating the LED device and the Schottky diode on the same substrate and connecting the LED device and the Schottky diode in parallel. In addition, in order to improve ESD resistance, a method of connecting an LED device in parallel with a Zener diode has been proposed.

However, these methods have the problem of purchasing and assembling a separate zener diode or forming a Schottky junction, thereby increasing the overall manufacturing cost of the device.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to reduce the operating voltage, improve the current spreading effect, minimize the blue-shift phenomenon of the LED device, and improve the luminous efficiency. It is to provide a nitride semiconductor light emitting device that can be.

In addition, an object of the present invention is to provide a nitride semiconductor light emitting device that can implement a high ESD resistance without having to provide a separate device for improving the ESD resistance.

A nitride semiconductor light emitting device according to an embodiment of the present invention for achieving the above object, an n-type cladding layer formed on a substrate; An active layer formed on the n-type cladding layer; A p-type cladding layer formed on the active layer; A p-type current diffusion layer having a multilayer structure disposed in the p-type cladding layer and having a nitride semiconductor layer having different energy bands and thicknesses stacked thereon; And it may include a p-type contact layer formed on the p-type cladding layer.

Herein, the p-type current spreading layer is composed of In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition, and may be formed by different composition ratios of Al and In. Can be.

The p-type current spreading layer may include a first nitride semiconductor layer higher than an energy band of the p-type cladding layer and a second nitride semiconductor layer lower than an energy band of the p-type cladding layer.

In addition, an energy band of the nitride semiconductor layer constituting the first nitride semiconductor layer and the second nitride semiconductor layer may have a smaller difference from the energy band of the p-type cladding layer toward the upper layer.

In addition, the first nitride semiconductor layer and the second nitride semiconductor layer may be periodically stacked.

In addition, the first nitride semiconductor layer and the second nitride semiconductor layer may be stacked aperiodically.

The semiconductor device may further include at least one nitride semiconductor layer in which an energy band is sequentially increased in any one direction between the first nitride semiconductor layer and the second nitride semiconductor layer.

In addition, the p-type current spreading layer may include a nitride semiconductor layer doped with p-type impurities.

In addition, the nitride semiconductor layer doped with the p-type impurity may further include a surfactant.

In addition, the p-type current spreading layer may be formed over the entire p-type cladding layer.

In addition, the p-type current spreading layer may have a stepped energy bandgap profile.

In addition, the p-type current spreading layer may have an energy bandgap profile having spikes in the form of sharp peaks.

The n-type cladding layer may further include an n-type current diffusion layer having a multilayer structure in which nitride semiconductor layers having different energy bands and thicknesses are stacked.

In addition, the n-type current spreading layer, In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition, it is formed by varying the composition ratio of Al and In Can be.

In addition, the n-type current spreading layer may include a first nitride semiconductor layer higher than the energy band of the n-type cladding layer and a second nitride semiconductor layer lower than the energy band of the n-type cladding layer.

In addition, the first nitride semiconductor layer and the second nitride semiconductor layer may be periodically stacked.

In addition, the first nitride semiconductor layer and the second nitride semiconductor layer may be stacked aperiodically.

The semiconductor device may further include at least one nitride semiconductor layer in which an energy band is sequentially increased in any one direction between the first nitride semiconductor layer and the second nitride semiconductor layer.

In addition, the n-type current diffusion layer may include a nitride semiconductor layer doped with n-type impurities.

In addition, the nitride semiconductor layer doped with the n-type impurity may further include a surfactant.

In addition, the n-type current spreading layer may be formed over the entirety of the n-type cladding layer.

In addition, the semiconductor device may further include a p-type current diffusion layer having a multilayer structure disposed in the p-type contact layer and having nitride energy layers having different energy bands and thicknesses stacked thereon.

As described above, according to the nitride semiconductor light emitting device according to the present invention, a p-type current diffusion layer having a multilayered structure in which nitride semiconductor layers having different energy bands and thicknesses are stacked in a p-type cladding layer has a current diffusion effect. And stress relaxation effects.

In addition, the present invention has the effect of lowering the operating voltage and minimizing the blue-shift due to the improvement of the current diffusion effect as described above to obtain a high light output.

Also, in the present invention, in the n-type cladding layer and the p-type contact layer, the n-type current diffusion layer and the p-type current diffusion layer having a multi-layer structure formed by sequentially stacking nitride semiconductor layers having different energy bands and thicknesses, respectively, The current spreading effect can be further improved.

In addition, since a structure in which nitride semiconductor layers having different energy bands of the p-type or n-type current spreading layers are sequentially stacked serves as a kind of capacitor, there is no need to provide another device for improving ESD resistance. This has the advantage of improving ESD immunity.

Matters relating to the effect of the nitride semiconductor light emitting device according to the present invention, including the technical configuration for the above object will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of 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.

<First Example  >

Hereinafter, the nitride semiconductor light emitting device according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4.

First, Figure 1 is a cross-sectional view showing the structure of the nitride semiconductor light emitting device according to the first embodiment of the present invention.

As shown in FIG. 1, the nitride semiconductor light emitting device according to the first embodiment of the present invention includes a substrate 101 that is light transmissive, a buffer layer 102, and an n-type cladding that are sequentially stacked on the substrate 101. Layer 103, active layer 104, p-type cladding layer 105, and p-type contact layer 106.

The substrate 101 is a substrate suitable for growing a nitride semiconductor single crystal, and may be a heterogeneous substrate such as a sapphire substrate and a silicon carbonate (SiC) substrate or a homogeneous substrate such as a nitride substrate.

The buffer layer 102 may be formed of AlN / GaN or the like as a layer for improving lattice matching with the substrate 101 before growing the n-type cladding layer 103.

The n-type cladding layer 103, the active layer 104, and the p-type cladding layer 105 may have an In _X Al _Y Ga _{1 -XY} N composition formula (where _{0 ≦} X, 0 ≦ Y, and X + Y ≦ 1). It can be made of a semiconductor material having a). More specifically, the n-type cladding layer 103 may be formed of an InAlGaN layer doped with n-type conductive impurities. For example, Si, Ge, Sn, etc. may be used as the n-type conductive impurities. For example, Si may be mainly used.

In addition, the p-type cladding layer 105 and the p-type contact layer 106 may be formed of an InAlGaN layer doped with a p-type conductive impurity. For example, Mg, Zn, Be or the like can be used, and preferably Mg can be mainly used.

The active layer 104 may be formed of an InGaN / GaN layer having a multi-quantum well structure.

In particular, in the nitride semiconductor light emitting device according to the first embodiment of the present invention, a p-type current diffusion layer 200 having a multilayer structure in which nitride semiconductor layers having different energy bands and thicknesses are stacked in the p-type cladding layer 105. ) Is formed. The p-type current spreading layer 200 increases the cladding effect, the current spreading and the stress relaxation effect of the p-type cladding layer 105 by varying the energy band and thickness of the nitride semiconductor layer constituting the same, and shortens the wavelength. This is to minimize the blue-shift phenomenon and to enhance the resistance of the electrostatic discharge (ESD) characteristics.

2 is a partial cross-sectional view illustrating a p-type current spreading layer according to a first embodiment of the present invention, and FIG. 3 is a graph schematically showing an example of an energy band gap profile of the p-type current spreading layer of FIG. 2.

2 and 3, in the p-type cladding layer 105, nitride semiconductor layers having different energy bands and thicknesses, for example, based on the energy band of the p-type cladding layer 105, may be used. P-type multi-layer structure in which at least one first nitride semiconductor layer 201a, 201b, 201c having a high energy band and at least one second nitride semiconductor layer 202a, 202b, 202c having a lower energy band are stacked The current spreading layer 200 is formed.

The nitride semiconductor layers constituting the first and second nitride semiconductor layers 201a, 201b, 201c, 202a, 202b, and 202c may also have different energy bands and thicknesses as shown in the drawing. The energy bands of the nitride semiconductor layers constituting the first nitride semiconductor layers 201a, 201b, and 201c and the second nitride semiconductor layers 202a, 202b, and 202c are, as shown in FIG. 3, the p-type cladding layer 105 toward the upper layer. It is desirable that the difference with the energy band becomes small. In this way, the overflow of the electrons is suppressed by the p-type current diffusion layer 200 and the inflow of holes can be maximized to maximize the luminous efficiency, and the current diffusion efficiency can be increased.

Here, the first and second nitride semiconductor layers 201a, 201b, 201c, 202a, 202b and 202c constituting the p-type current spreading layer 200 may be In _X Al _Y Ga _{1 -X - Y} N (0 ≤X, 0≤Y, X + Y≤1) composition, and may have different energy bands through different composition ratios of Al and In.

For example, AlGaN may be used as the first nitride semiconductor layers 201a, 201b, and 201c, and InGaN may be used as the second nitride semiconductor layers 202a. 202b, 202c.

The nitride semiconductor layer formed on the lowermost layer of the nitride semiconductor layers constituting the p-type current spreading layer 200 may be made of any of an AlGaN layer and an InGaN layer.

It is preferable that all or part of the nitride semiconductor layer constituting the p-type current spreading layer 200 is doped with a p-type impurity, and a surfactant may be added when the p-type impurity is doped. In may be used as the surfactant, which lowers the activation energy of the p-type impurity, thereby lowering the operating voltage of the light emitting device.

Here, the stress buffer layer 203 which is a nitride semiconductor layer between the first nitride semiconductor layers 201a, 201b and 201c and the second nitride semiconductor layers 202a, 202b and 202c constituting the p-type current spreading layer 200. ) May be further formed.

The stress buffer layer 203 is made of a semiconductor material having an In _X Al _Y Ga _{1 -X- Y} N composition formula, where 0≤X, 0≤Y, and X + Y≤1, and In and Al are different from each other. The composition ratio controls the difference in energy band gap between the first nitride semiconductor layers 201a, 201b and 201c and the second nitride semiconductor layers 202a, 202b and 202c.

That is, the stress buffer layer 203 buffers an energy band gap rapidly changing at an interface between the first nitride semiconductor layers 201a, 201b, and 201c and the second nitride semiconductor layers 202a, 202b, and 202c. It is possible to keep the characteristics more stable.

The stress buffer layer 203 may be formed as one layer or a plurality of layers between the first nitride semiconductor layers 201a, 201b, and 201c and the second nitride semiconductor layers 202a, 202b, and 202c. When the stress buffer layer 203 is formed of a plurality of layers, the stress buffer layer 203 may be formed of at least one nitride semiconductor layer in which an energy band is sequentially increased.

The p-type current spreading layer 200 is higher than the energy band of the p-type cladding layer 105 and the energy bands of the first nitride semiconductor layers 201a, 201b, and 201c and the p-type cladding layer 105. The lower second nitride semiconductor layers 202a, 202b, and 202c may be periodically stacked, such as being repeatedly stacked one or more times alternately.

For example, in the p-type current diffusion layer 200 including the stress buffer layer 203, AlGaN / GaN / InGaN / GaN may form one cycle of a multilayer structure, and AlGaN / GaN / InGaN is one cycle of a multilayer structure. May be formed, and may be stacked in various cycles such that the reverse order may form one cycle of the multilayer structure.

However, the first nitride semiconductor layers 201a, 201b, and 201c and the second nitride semiconductor layers 202a, 202b, and 202c may be stacked aperiodically.

In the p-type current spreading layer 200 according to the present embodiment, an energy band is rapidly changed at an interface between the first nitride semiconductor layers 201a, 201b, and 201c and the second nitride semiconductor layers 202a, 202b, and 202c. The discontinuity of the energy band forms a two-dimensional electron gas layer (not shown) at its interface.

Accordingly, in the present invention, when a voltage is applied, a tunneling phenomenon occurs through the p-type current diffusion layer 200 to the n ⁺ -p ⁺ junction, thereby improving the cladding effect of the p-type cladding layer 105, and Carrier mobility can be secured to improve the current diffusion effect.

As such, when the current spreading effect is improved through the p-type current spreading layer 200, the operating voltage Vf is lowered and the blue-shift phenomenon is minimized due to the increase in the light emitting area. Can be improved.

The blue-shift phenomenon is further reduced as the In flow rate of the nitride semiconductor layer having a low energy band gap due to the composition of high In in the nitride semiconductor layer forming the p-type current spreading layer 200 increases. do.

In addition, according to the embodiment of the present invention, by forming different thicknesses of the nitride semiconductor layers constituting the p-type current spreading layer 200, a stress relaxation effect can be obtained.

In addition, the second nitride semiconductor layers 202a, 202b, and 202c made of InGaN of the p-type current diffusion layer 200 are interposed between the first nitride semiconductor layers 201a, 201b, and 201c made of AlGaN, and have a relatively high dielectric constant. Since the p-type current spreading layer 200 can serve as a kind of capacitor. Therefore, the p-type current spreading layer 200 can protect the light emitting device from a sudden surge voltage or electrostatic phenomenon, thereby improving the ESD resistance of the device.

The p-type current spreading layer 200 as described above may be formed on at least a portion of the p-type cladding layer 105 to form part or all of the p-type cladding layer 105.

The p-type current spreading layer 200 may have a stepped energy bandgap profile as shown in FIG. 3, but may have a different energy bandgap profile.

4 is a graph schematically showing another example of the energy band gap profile of the p-type current spreading layer according to the first embodiment of the present invention.

As shown in FIG. 4, the p-type current spreading layer 200 may have an energy bandgap profile having spikes in the form of sharp peaks. This type of energy bandgap profile may be implemented by delta doping.

<2nd Example  >

A nitride semiconductor light emitting device according to a second exemplary embodiment of the present invention will be described with reference to FIG. 5. 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 illustrating a structure of a nitride semiconductor light emitting device according to a second exemplary embodiment of the present invention.

The nitride semiconductor light emitting device according to the second embodiment of the present invention has the same configuration as that of the nitride semiconductor light emitting device according to the first embodiment, but as shown in FIG. 5, the n-type cladding layer 103 The first embodiment differs only in that an n-type current spreading layer 300 having a multilayer structure in which nitride semiconductor layers having different energy bands and thicknesses are stacked is further formed.

A nitride semiconductor layer having different energy bands and thicknesses constituting the n-type current spreading layer 300 may include In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1). It consists of a composition, it can be formed by varying the composition ratio of Al and In.

The n-type current spreading layer 300 may include one or more first nitride semiconductor layers (not shown) having a higher energy band and lower energy bands based on the energy band of the n-type cladding layer 103. The branch may be formed by laminating one or more second nitride semiconductor layers (not shown) periodically or aperiodically.

In this case, one or more stress buffer layers may be further formed between the first nitride semiconductor layer and the second nitride semiconductor layer constituting the n-type current diffusion layer 300.

Some or all layers of the nitride semiconductor layer constituting the n-type current diffusion layer 300 are preferably doped with n-type impurities, and a surfactant such as In may be added together with the n-type impurities.

The n-type current spreading layer 300 may be formed over part or the entirety of the n-type cladding layer 103.

The second embodiment of the present invention has the advantages that the same action and effect as in the first embodiment can be obtained, and the cladding effect and the current spreading effect of the n-type cladding layer 103 can be improved. have.

<3rd Example  >

A nitride semiconductor light emitting device according to a third exemplary embodiment of the present invention will be described with reference to FIG. 6. However, the description of the same parts as those of the second embodiment of the configuration of the third embodiment will be omitted, and only the configuration that is different from the third embodiment will be described in detail.

6 is a cross-sectional view illustrating a structure of a nitride semiconductor light emitting device according to a third exemplary embodiment of the present invention.

The nitride semiconductor light emitting device according to the third embodiment of the present invention has the same configuration as that of the nitride semiconductor light emitting device according to the second embodiment, except that the p-type contact layer 106 is shown in FIG. 6. It differs from the second embodiment only in that a p-type current spreading layer 200 having a multilayer structure in which nitride semiconductor layers having different energy bands and thicknesses are stacked is further formed therein.

This third embodiment can not only obtain the same functions and effects as in the second embodiment, but can further improve the current spreading effect of the device.

Preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and various substitutions, modifications, and changes within the scope without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It will be possible, but such substitutions, changes and the like should be regarded as belonging to the following claims.

1 is a cross-sectional view showing the structure of a nitride semiconductor light emitting device according to the first embodiment of the present invention.

2 is a partial cross-sectional view showing a p-type current spreading layer according to the first embodiment of the present invention.

3 is a graph schematically illustrating an example of an energy band gap profile of the p-type current spreading layer of FIG. 2.

4 is a graph schematically showing another example of an energy band gap profile of a p-type current spreading layer according to a first embodiment of the present invention.

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

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

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

101: substrate 102: buffer layer

103: n-type cladding layer 104: active layer

105: p-type cladding layer 106: p-type contact layer

200: p-type current diffusion layer 300: n-type current diffusion layer

Claims (22)

An n-type cladding layer formed on the substrate; An active layer formed on the n-type cladding layer; A p-type cladding layer formed on the active layer; A p-type current diffusion layer having a multilayer structure disposed in the p-type cladding layer and having a nitride semiconductor layer having different energy bands and thicknesses stacked thereon; And A p-type contact layer formed on the p-type cladding layer; Nitride semiconductor light emitting device comprising a. The method of claim 1, The p-type current spreading layer is formed of an In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition, and is formed of a nitride semiconductor light emitting device having a different composition ratio of Al and In. device. The method of claim 1, And the p-type current spreading layer comprises a first nitride semiconductor layer higher than the energy band of the p-type cladding layer and a second nitride semiconductor layer lower than the energy band of the p-type cladding layer. The method of claim 3, The nitride semiconductor light emitting element of which the energy band of the nitride semiconductor layer which comprises the said 1st nitride semiconductor layer and the said 2nd nitride semiconductor layer becomes smaller from an upper band to the p-type cladding layer energy band. The method of claim 3, A nitride semiconductor light emitting device in which the first nitride semiconductor layer and the second nitride semiconductor layer are periodically stacked. The method of claim 3, A nitride semiconductor light emitting device in which the first nitride semiconductor layer and the second nitride semiconductor layer are laminated aperiodically. The method of claim 3, The nitride semiconductor light emitting device of claim 1, further comprising at least one nitride semiconductor layer in which the energy band is sequentially increased in any one direction between the first nitride semiconductor layer and the second nitride semiconductor layer. The method of claim 1, And the p-type current spreading layer comprises a nitride semiconductor layer doped with p-type impurities. The method of claim 8, The nitride semiconductor layer doped with the p-type impurity further comprises a surfactant. The method of claim 1, And the p-type current spreading layer is formed over the entire p-type cladding layer. The method of claim 1, The p-type current diffusion layer is a nitride semiconductor light emitting device having a stepped energy band gap profile. The method of claim 1, The p-type current spreading layer is a nitride semiconductor light emitting device having an energy band gap profile having a spike portion of the pointed peak shape. The method of claim 1, The nitride semiconductor light emitting device of claim 9, further comprising an n-type current diffusion layer having a multilayer structure in which the nitride semiconductor layers having different energy bands and thicknesses are stacked. The method of claim 13, The n-type current spreading layer is formed of an In _X Al _Y Ga _{1 -X- Y} N (0≤X, 0≤Y, X + Y≤1) composition, and nitride semiconductor light emitting formed by varying the composition ratio of Al and In. device. The method of claim 13, The n-type current spreading layer includes a first nitride semiconductor layer higher than the energy band of the n-type cladding layer and a second nitride semiconductor layer lower than the energy band of the n-type cladding layer. The method of claim 15, A nitride semiconductor light emitting device in which the first nitride semiconductor layer and the second nitride semiconductor layer are periodically stacked. The method of claim 15, A nitride semiconductor light emitting device in which the first nitride semiconductor layer and the second nitride semiconductor layer are laminated aperiodically. The method of claim 15, The nitride semiconductor light emitting device of claim 1, further comprising at least one nitride semiconductor layer in which the energy band is sequentially increased in any one direction between the first nitride semiconductor layer and the second nitride semiconductor layer. The method of claim 13, The n-type current diffusion layer comprises a nitride semiconductor light emitting device doped with n-type impurities. The method of claim 19, The nitride semiconductor layer doped with the n-type impurity further comprises a surfactant. The method of claim 13, And the n-type current spreading layer is formed over the entirety of the n-type cladding layer. The method of claim 13, And a p-type current spreading layer having a multi-layer structure in which the nitride semiconductor layers having different energy bands and thicknesses are stacked in the p-type contact layer.

Images