KR101198759B1

KR101198759B1 - Nitride light emitting device

Info

Publication number: KR101198759B1
Application number: KR20070055360A
Authority: KR
Inventors: 문용태
Original assignee: 엘지이노텍 주식회사; 엘지전자 주식회사
Priority date: 2007-06-07
Filing date: 2007-06-07
Publication date: 2012-11-12
Also published as: KR20090003384A

Abstract

The present invention relates to a nitride-based light emitting device, and more particularly to a nitride-based light emitting device that can improve the luminous efficiency and reliability of the light emitting device. The present invention provides a nitride-based light emitting device comprising: a first quantum barrier layer; A stress relaxation layer positioned on the first quantum barrier layer; A second quantum barrier layer positioned on the stress relaxation layer; A quantum well layer positioned on the second quantum barrier layer; It is preferably configured to include at least one quantum well structure consisting of a first quantum barrier layer located on the quantum well layer.

Light emitting element, quantum well, stress, nitride, LED.

Description

Nitride-based light emitting device

1 is a cross-sectional view showing an example of a thin film structure of a light emitting element.

2 is a cross-sectional view showing another example of a thin film structure of a light emitting device.

3 is an energy band diagram of the thin film structure of FIG. 2.

4 is a cross-sectional view showing the thin film structure of the first embodiment of the present invention.

FIG. 5 is an energy band diagram of the thin film structure of FIG. 4.

6 is a cross-sectional view showing an example of the horizontal light emitting device according to the first embodiment.

7 is a cross-sectional view showing a thin film structure of a second embodiment of the present invention.

FIG. 8 is an energy band diagram of the thin film structure of FIG. 7.

9 is a cross-sectional view showing an example of the vertical light emitting device according to the second embodiment.

10 is a cross-sectional view showing a thin film structure according to a third embodiment of the present invention.

11 is a cross-sectional view showing a thin film structure according to a fourth embodiment of the present invention.

12 is a cross-sectional view showing a thin film structure according to a fifth embodiment of the present invention.

FIG. 13 is an energy band diagram of the thin film structure of FIG. 12.

10: electron injection layer 20: quantum well structure

21: first quantum barrier layer 22: stress relaxation layer

23: second quantum barrier layer 24: quantum well layer

30 light emitting layer 40 hole injection layer

50: substrate

The present invention relates to a nitride-based light emitting device, and more particularly to a nitride-based light emitting device that can improve the luminous efficiency and reliability of the light emitting device.

Light Emitting Diodes (LEDs) are well-known semiconductor light emitting devices that convert current into light.In 1962, red LEDs using GaAsP compound semiconductors were commercialized, along with GaP: N series green LEDs. It has been used as a light source for display images of electronic devices, including.

The wavelength of light emitted by such LEDs depends on the semiconductor material used to make the LEDs. This is because the wavelength of the emitted light depends on the band-gap of the semiconductor material, which represents the energy difference between the valence band electrons and the conduction band electrons.

Gallium nitride compound semiconductors (Gallium Nitride (GaN)) have high thermal stability and wide bandgap (0.8 to 6.2 eV), which has attracted much attention in the development of high-power electronic components including LEDs.

One reason for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers that emit green, blue and white light.

In this way, the emission wavelength can be adjusted to match the material's characteristics to specific device characteristics. For example, GaN can be used to create a white LED that can replace the blue LEDs and incandescent lamps that are beneficial for optical recording.

Due to the advantages of these GaN-based materials, the GaN-based LED market is growing rapidly. Therefore, since commercial introduction in 1994, GaN-based optoelectronic device technology has rapidly developed.

The brightness or output of the LED using the GaN-based material as described above is large, the structure of the active layer, the light extraction efficiency to extract light to the outside, the size of the LED chip, the type and angle of the mold (mold) when assembling the lamp package , Fluorescent material and the like.

On the other hand, one of the reasons why the growth of GaN-based semiconductors is more difficult than other III-V compound semiconductors is that there are no high-quality substrates, that is, wafers made of materials such as GaN, InN, and AlN.

Therefore, the LED structure is grown on a heterogeneous substrate such as sapphire, and many defects are generated, and these defects have a great influence on the LED performance.

In particular, the active layer for generating light in the LED structure has a nitride semiconductor multi-quantum well (MQW). In this multi-quantum well structure, the quantum well layer and the quantum barrier layer are repeatedly stacked, and electrons and holes injected from the n-type semiconductor layer and the p-type semiconductor layer, respectively, combine with each other in the quantum well layer to emit light. .

The quantum well layer and the quantum barrier layer constituting the quantum well structure have different material components, and stress may be applied to the quantum well layer due to the difference in the material components.

The stress acting on the quantum well layer deforms the energy band structure in the quantum well layer to greatly reduce the luminescence properties, and also lowers the interfacial characteristics between the quantum barrier layer and the quantum well layer. Can be lowered.

An object of the present invention is to provide a nitride-based light emitting device of high brightness by effectively solving the stress problem acting on the light emitting layer of the light emitting device.

In order to achieve the above technical problem, the present invention, the nitride-based light emitting device, the first quantum barrier layer; A stress relaxation layer positioned on the first quantum barrier layer; A second quantum barrier layer positioned on the stress relaxation layer; A quantum well layer positioned on the second quantum barrier layer; It is preferably configured to include at least one quantum well structure consisting of a first quantum barrier layer located on the quantum well layer.

The stress relaxation layer may have a plane lattice constant value between the first quantum barrier layer and the quantum well layer. The energy band gap of the stress relaxation layer may have an energy band gap between the first quantum barrier layer and the quantum well layer.

The stress relaxation layer may have a thickness of 1 to 15 nm, and when a plurality of quantum well structures are formed, at least one or more of the stress relaxation layers may include an n-type dopant.

On the other hand, the stress relaxation layer, the average composition may comprise an In component of 0.1 to 5%.

The energy band gap of the second quantum barrier layer may be greater than the energy band gap of the stress mitigating layer, and the thickness of the second quantum barrier layer may be thinner than the thickness of the first quantum barrier layer. In addition, the thickness of the second quantum barrier layer may be 0.2 to 5nm.

When the quantum well structure described above is a multiple quantum well structure composed of a plurality, at least one or more of the first quantum barrier layer and the quantum well layer may be formed including an n-type dopant.

Meanwhile, a second stress relaxation layer may be further included between the quantum well layer and the first quantum barrier layer, and the second stress relaxation layer may have a superlattice structure in which gallium nitride / indium gallium nitride is repeated.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

Like reference numerals denote like elements throughout the description of the drawings. In the drawings the dimensions of layers and regions are exaggerated for clarity. In addition, each embodiment described herein includes an embodiment of a complementary conductivity type.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between . If a part of a component, such as a surface, is expressed as 'inner', it will be understood that this means that it is farther from the outside of the device than other parts of the element.

Furthermore, relative terms such as "beneath" or "overlies" refer to the relationship of one layer or region to one layer or region and another layer or region with respect to the substrate or reference layer, as shown in the figures. Can be used to describe.

It will be understood that these terms are intended to include other directions of the device in addition to the direction depicted in the figures. Finally, the term 'directly' means that there is no element in between. As used herein, the term 'and / or' includes any and all combinations of one or more of the recorded related items.

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers, and / or regions, such elements, components, regions, layers, and / or regions It will be understood that it should not be limited by these terms.

These terms are only used to distinguish one element, component, region, layer or region from another region, layer or region. Thus, the first region, layer or region discussed below may be referred to as the second region, layer or region.

Embodiments of the present invention will be described with reference to a gallium nitride (GaN) based light emitting device formed on a nonconductive substrate such as, for example, a sapphire (Al ₂ O ₃ ) based substrate. However, the present invention is not limited to this structure.

1 illustrates a basic thin film structure of a high brightness nitride semiconductor light emitting device that is currently widely commercialized. The basic structure of the LED of the GaN-based material is a light emitting layer 2 having a quantum well structure between the n-type electron injection layer 1 and the p-type hole injection layer 3.

In general, the light emitting layer 2 generating light has a nitride semiconductor multi-quantum well (MQW).

In this multi-quantum well structure, a quantum well layer 4 and a quantum barrier layer 5 are repeatedly stacked, so that the n-type electron injection layer 1 and the p-type hole injection layer 3 are stacked. Electrons and holes injected from each other are combined with each other in the quantum well layer 4 to emit light.

In this case, the quantum well layer 4 is disposed between the two quantum barrier layers 5 to constrain the electrons and holes quantum mechanically.

Therefore, in order to implement a high-brightness light emitting device, electrons and holes should be transported well to the quantum well layer 4, and transported electrons and holes should be able to be efficiently combined in the quantum well layer 4.

As a result, thin film crystallinity of the quantum well layer 4 and the quantum barrier layer 5 should be very excellent in order to implement a high brightness light emitting device.

Currently, the most representative multi-quantum well structure of a nitride semiconductor light emitting device is a gallium nitride (GaN) quantum barrier layer (5) having a relatively large band gap and an indium gallium nitride (InGaN) quantum well layer (4) having a relatively small band gap. Is done. At this time, gallium nitride and indium gallium nitride are prepared as a high quality thin film having excellent crystallinity in order to increase luminous efficiency.

By the way, gallium nitride and indium gallium nitride inherently have a very large crystal lattice mismatch. This is because the atomic radius of indium is larger than that of gallium, and the bonding force and bond length of indium and nitrogen are weaker and longer than the bonding force and bond length of gallium and nitrogen, respectively.

Therefore, the indium gallium nitride quantum well layer 4 is severely subjected to compressive stress. This compressive stress deforms the energy band structure in the quantum well layer 4 so that electrons and holes are spatially separated in the quantum well, and thus the luminous efficiency of the light emitting device may be reduced.

In addition, such compressive stress may lower the interface characteristics between the gallium nitride quantum barrier layer 5 and the indium gallium nitride quantum well layer 4, resulting in loss of carriers at the interface, and thus, lowering the luminous efficiency of the light emitting device. .

In order to fundamentally overcome the above-mentioned problems to use a quantum well structure comprising a nitride stress relieving layer _{(In v Al w Ga 1 -v-} w N, 0≤v, w≤1, 0≤v + w≤1) Can be.

That is, a structure capable of improving such a phenomenon is, as shown in FIG. 2, on the n-type electron injection layer 10, the first quantum barrier layer 21 / stress relaxation layer 22 / second quantum. A light emitting layer 30 comprising a quantum well structure 20 in which the barrier layer 23 / quantum well layer 24 / first quantum barrier layer 21 is laminated in this order, and as shown, In 30), the quantum well structure 20 may be configured by repeating at least two or more times.

The p-type hole injection layer 40 is formed on the light emitting layer 30. In the light emitting layer 30, electrons and holes injected from the electron injection layer 10 and the hole injection layer 40 are coupled to each other. Radiates light.

The stress relaxation layer 22 constituting the quantum well structure 20 has an in-plane lattice constant of the first quantum barrier layer 21 in order to effectively relieve stress in the light emitting layer 30. It may have a value between the constant and the plane lattice constant value of the quantum well layer 24.

In addition, as shown in FIG. 3, the stress relaxation layer 22 has a bandgap value of the first quantum barrier layer 21 and a quantum well layer so that an energy band gap thereof can effectively inject electrons and holes into the quantum well. (24) may have a value between the bandgap values.

In some cases, the stress relaxation layer 22 may form a superlattice layer.

On the other hand, the stress relaxation layer 22 may perform a quantum mechanical function. That is, the second quantum barrier layer 23 is positioned between the stress relaxation layer 22 and the quantum well layer 24 so that the electrons injected from the n-type electron injection layer 10 can be effectively applied to the stress relaxation layer 22. Gathered and constrained, the electrons constrained in the stress relaxation layer 22 can be effectively injected into the quantum well layer 24.

In consideration of this quantum mechanical function, the thickness of the stress relaxation layer 22 preferably has a thickness of 1 to 15 nanometers (nm).

In addition, the second quantum barrier layer 23 has a thickness of 1 so that the stress relaxation layer 22 effectively alleviates the stress caused by the lattice mismatch between the first quantum barrier layer 21 and the quantum well layer 24. It is desirable to be smaller than the difference quantum barrier layer 21.

The second quantum barrier layer 23 may have a thickness of 0.2 nm to 5 nm, and the energy band gap value of the second quantum barrier layer 23 may be an energy band gap value of the stress relaxation layer 22. Can be greater than The second quantum barrier layer 23 may function to effectively constrain luminescence coupling by electrons and holes being constrained quantum mechanically in the quantum well layer 24.

Meanwhile, one or more of the stress relaxation layers 22 in the multi-quantum well structure 20 may be doped by an n-type dopant to increase the coupling efficiency of electrons and holes in the quantum well layer 24. Can be.

As described above, the stress relaxation layer 22 and the first and second quantum barrier layers 21 and 23 located in the light emitting layer 30 of the multi-quantum well structure 20 are essentially present in the quantum well layer 24. The compressive stress can be dramatically reduced, and the internal quantum efficiency of the light emitting device can be dramatically improved by effectively constraining electrons and holes in the quantum well layer 24.

That is, the stress relaxation layer 22 effectively alleviates the compressive stress caused by the lattice constant mismatch between the quantum barrier layers 21 and 23 and the quantum well layer 24, thereby effectively reducing the stress in the quantum well layer 24. The stress distribution and the indium composition distribution can be made more uniform to further improve the optical characteristics.

In addition, the interface characteristics between the quantum barrier layers 21 and 23 and the quantum well layer 24 may be improved, thereby greatly reducing the carrier loss at the interface, thereby greatly improving the luminous efficiency.

As a result, it is possible to realize a high brightness high efficiency light emitting device by dramatically increasing the internal quantum efficiency, which is an essential optical characteristic of the light emitting device.

&Lt; Embodiment 1 >

In the first embodiment of the present invention shown in FIG. 4, metal organic chemical vapor deposition (MOCVD) was used for growing a nitride semiconductor thin film. Sapphire was used as the substrate 50.

Ammonia was used as the nitrogen source and hydrogen and nitrogen were used as the carrier gas. Gallium, indium and aluminum used an organometallic source. The n-type dopant was made of silicon (Si) and the p-type dopant was made of magnesium (Mg). An n-type gallium nitride (GaN) semiconductor electron injection layer 10 of 4 micrometers (μm) was grown on the sapphire substrate at 1050 ° C., and a pressure of 200 Torr was applied.

On it, a light emitting layer 30 having a band structure as shown in FIG. 5 was grown. That is, the first quantum barrier layer 21 of gallium nitride (GaN) having a size of 10 nm was grown at a temperature of 850 ° C. On it, an indium gallium nitride (InGaN) stress relaxation layer 22 having a thickness of 3 nm was grown. At this time, the indium source amount and the growth temperature were controlled so that the average indium composition of the indium gallium nitride stress relaxation layer 22 was about 3%.

On it, a gallium nitride second quantum barrier layer 23 having a size of 1 nm was grown. Thereafter, an indium gallium nitride quantum well layer 24 having a thickness of 2.5 nm was grown at a temperature of 700 ° C. The indium source amount of the indium gallium nitride quantum well 24 was controlled to be about 22%.

Repeating the same sequence, all eight pairs of gallium nitride first quantum barrier layer 21 / indium gallium nitride stress relaxation layer 22 / gallium nitride second quantum barrier layer 23 / indium gallium nitride quantum well layer 24 The light emitting layer 30 having the multi-quantum well structure 20 formed of the same was grown.

The p-type gallium nitride hole injection layer 40 having a thickness of 0.1 μm was grown on the light emitting layer 30 of the nitride semiconductor multi-quantum well structure 20.

Thereafter, as shown in FIG. 6, the p-type hole injection layer 40 and the light emitting layer 30 are etched using an etching apparatus to expose a portion of the n-type electron injection layer 10 and then the n-type electrode 11. Formed. In addition, the p-type electrode 41 may be formed on the p-type hole injection layer 40 for hole injection to form a lateral or horizontal light emitting device structure.

&Lt; Embodiment 2 >

In the second embodiment, as shown in FIG. 7, the n-type nitride semiconductor electron injection layer 110 having a thickness of 4 μm was grown on the sapphire substrate 150 at 1050 ° C., and the pressure was 200 Torr.

On it, a light emitting layer 130 having a band structure of the quantum well structure 120 as shown in FIG. 8 was grown. That is, first, the first gallium nitride quantum barrier layer 121 having a size of 10 nm was grown at a temperature of 850 ° C. On it, an indium gallium nitride stress relaxation layer 122 having a thickness of 3 nm was grown.

An n-type dopant source was injected during growth of the stress relaxation layer 122. The indium source amount and the growth temperature were controlled such that the average indium composition of the indium gallium nitride stress relaxation layer 122 was about 0.1 to 5%.

On it, a gallium nitride second quantum barrier layer 123 having a size of 0.2 to 3 nm was grown. An indium gallium nitride quantum well layer 124 having a thickness of 2.5 nm was grown thereon at a temperature of 700 ° C. The indium composition of the indium gallium nitride quantum well layer 124 was controlled to be about 22%.

Repeating the same sequence, all eight pairs of gallium nitride first quantum barrier layer 121 / indium gallium nitride stress relaxation layer 122 / gallium nitride second quantum barrier layer 123 / indium gallium nitride quantum well layer 124 The light emitting layer 130 having the multi-quantum well structure 120 formed of the same was grown.

The p-type gallium nitride hole injection layer 140 having a thickness of 0.1 μm was grown on the light emitting layer 130 having the nitride semiconductor multi-quantum well structure.

Subsequently, the process of manufacturing the side type or horizontal type light emitting device may be the same as in the first embodiment.

In some cases, the structure of the vertical light emitting device can be manufactured. That is, an ohmic electrode or a reflective ohmic electrode 160 is formed on the p-type hole injection layer 140, and a support layer 170 made of a semiconductor or a metal is formed thereon.

Thereafter, if the substrate 150 is removed and the n-type electrode 180 is formed on the electron injection layer 110 exposed by removing the substrate 150 as described above, a vertical light emitting device structure as illustrated in FIG. 9 may be formed. have.

Third Embodiment

As shown in FIG. 10, a 4 μm n-type nitride semiconductor electron injection layer 210 was grown on the sapphire substrate 240 at 1050 ° C., and a pressure of 200 Torr was applied.

On it, a light emitting layer 220 having a structure as follows was grown. That is, the first quantum barrier layer of indium gallium nitride having a size of 10 nm was grown at a temperature of 850 ° C. The indium composition of the first quantum barrier layer was injected into the growth equipment by controlling the amount of the indium source to be about 0.3%.

On it, an indium gallium nitride stress relaxation layer having a thickness of 1 to 7 nm was grown. The indium source amount and the growth temperature were controlled so that the average indium composition of the indium gallium nitride stress relaxation layer was about 1 to 5%.

On it, a second quantum barrier layer of indium gallium nitride having a size of 0.2 to 3 nm was grown. The indium source amount was controlled so that the indium composition of the indium gallium nitride second quantum barrier layer was about 0.3%.

An indium gallium nitride quantum well layer having a thickness of 2 to 3 nm was grown thereon at a temperature of 700 ° C. The amount of indium source was controlled so that the indium composition of the indium gallium nitride quantum well layer was about 16 to 25%.

The light emitting layer having a multi-quantum well structure composed of eight pairs of indium gallium nitride first quantum barrier layer / indium gallium nitride stress relaxation layer / indium gallium nitride second quantum barrier layer / indium gallium nitride quantum well layer 220).

Of these, n-type dopant sources were injected into the initial two to six stress relaxation layers among the eight stress relaxation layers.

Among the first quantum barrier layers in the light emitting layer 220, n-type dopant sources were implanted into the first two to four first quantum barrier layers. The p-type gallium nitride hole injection layer 230 having a thickness of 0.1 μm was grown on the light emitting layer 220 having the nitride semiconductor multi-quantum well structure.

Thereafter, as in the first embodiment, a horizontal light emitting device structure may be manufactured or a vertical light emitting device structure may be manufactured as in the second embodiment.

As shown in FIG. 11, a 4 μm n-type nitride semiconductor electron injection layer 310 was grown on the sapphire substrate 340 at 1050 ° C., and a pressure of 200 Torr was applied.

On the light emitting layer 320 having the following structure was formed. That is, the first quantum barrier layer of indium gallium nitride having a size of 10 nm was grown at a temperature of 850 ° C. On it, a 3 nm thick indium gallium nitride stress relaxation layer was grown. The amount of indium source and the growth temperature were controlled so that the average indium composition of the stress relaxation layer was about 3%.

On it, a second quantum barrier layer of indium gallium nitride having a size of 1 nm was grown. A 3 nm thick indium gallium nitride quantum well layer was grown thereon at a temperature of 760 ° C. The indium composition of the quantum well layer was controlled to be about 16%.

The same procedure was repeated to form the light emitting layer 320 including all eight pairs of indium gallium nitride first quantum barrier layer / indium gallium nitride stress relaxation layer / indium gallium nitride second quantum barrier layer / indium gallium nitride quantum well layer. Among the eight stress relaxation layers, the first two stress relaxation layers were injected with an n-type dopant source.

The first four quantum barrier layers among the first quantum barrier layers in the light emitting layer 320 were injected with an n-type dopant source. In addition, among the quantum well layers in the light emitting layer 320, the first 1 to 4 quantum well layers were grown by implanting an n-type dopant source.

The p-type gallium nitride hole injection layer 330 having a thickness of 0.1 μm was grown on the light emitting layer 320 of the nitride semiconductor multi-quantum well structure.

As shown in FIG. 12, an n-type nitride semiconductor electron injection layer 410 having a thickness of 4 μm was grown on the sapphire substrate 440 at 1050 ° C., and a pressure of 200 Torr was applied.

A light emitting layer 420 having a structure as shown in FIG. 13 was formed thereon. That is, the first gallium nitride quantum barrier layer 421 having a thickness of about 7 nm was grown at a temperature of 900 ° C. On it, a 3 nm thick indium gallium nitride first stress relaxation layer 422 was grown.

The indium source amount and the growth temperature were controlled such that the average indium composition of the first stress relaxation layer 422 was about 2%. On it, a gallium nitride second quantum barrier layer 423 having a thickness of 1 nm was grown.

An indium gallium nitride quantum well layer 424 having a thickness of 3 nm was grown on the second quantum barrier layer 423 at a temperature of 710 ° C.

The second stress relaxation layer 425 may be grown on the quantum well layer 424, and the first quantum barrier layer 421 having a thickness of 7 nm may be disposed on the second stress relaxation layer 425.

The second stress relaxation layer may have a structure as follows. That is, a gallium nitride layer having a thickness of about 0.5 nm is grown at a temperature of 900 deg. C, and indium gallium nitride (about 0.2% of indium composition) having a thickness of about 0.5 nm is continuously grown thereon.

The gallium nitride may have a superlattice structure including 2 to 10 pairs of gallium nitride and indium gallium nitride having an indium composition of about 0.2%.

On the other hand, the amount of indium source was controlled so that the indium composition of the quantum well layer 424 was about 23%. The same sequence was repeated to grow all eight pairs of nitride semiconductor multi quantum well structure light emitting layers 420.

Among the eight first stress relaxation layers 422, the first two first stress relaxation layers 422 were injected with an n-type dopant source. The first four quantum barrier layers 421 of the first quantum barrier layer 421 in the emission layer 420 were injected with an n-type dopant source.

Among the quantum well layers 424 in the light emitting layer 420, the first two quantum well layers 424 were grown by implanting an n-type dopant source.

The p-type gallium nitride hole injection layer 430 having a thickness of 0.1 μm was grown on the light emitting layer 420 of the nitride semiconductor multi-quantum well structure having such a structure.

The above embodiment is an example for explaining the technical idea of the present invention in detail, and the present invention is not limited to the above embodiment, various modifications are possible, and various embodiments of the technical idea are all protected by the present invention. It belongs to the scope.

The present invention as described above has the following effects.

First, the internal quantum efficiency of the light emitting device can be dramatically improved by significantly reducing the compressive stress inherently present in the light emitting layer and effectively constraining electrons and holes in the quantum well layer.

Second, as described above, the compressive stress of the light emitting layer can be effectively alleviated to make the stress distribution and the indium composition distribution in the quantum well layer more uniform, thereby further improving the optical characteristics.

Third, the interfacial characteristics between the quantum barrier layer and the quantum well layer are improved, thereby greatly reducing the carrier loss at the interface, thereby greatly improving the luminous efficiency.

Fourth, it is possible to implement a light emitting device having high brightness and high efficiency by dramatically increasing the internal quantum efficiency, which is an essential optical characteristic of the light emitting device.

Claims

In the nitride-based light emitting device,

A first quantum barrier layer;

A stress relaxation layer positioned on the first quantum barrier layer;

A second quantum barrier layer positioned on the stress relaxation layer;

A quantum well layer positioned on the second quantum barrier layer;

A nitride-based light emitting device comprising at least one quantum well structure consisting of a first quantum barrier layer located on the quantum well layer.

The nitride-based light emitting device according to claim 1, wherein the stress relaxation layer has a value between the first quantum barrier layer and the quantum well layer.

The nitride-based light emitting device according to claim 1, wherein the energy band gap of the stress relaxation layer has an energy band gap between the first quantum barrier layer and the quantum well layer.

The nitride-based light emitting device according to claim 1, wherein the stress relaxation layer has a thickness of 1 to 15 nm.

The nitride-based light emitting device according to claim 1, wherein at least one of the stress relaxation layers comprises an n-type dopant.

The nitride-based light emitting device according to claim 1, wherein the stress relaxation layer comprises an In component having an average composition of 0.1 to 5%.

The nitride-based light emitting device according to claim 1, wherein an energy band gap of the second quantum barrier layer is larger than an energy band gap of the stress relaxation layer.

The nitride-based light emitting device according to claim 1, wherein the thickness of the second quantum barrier layer is thinner than the thickness of the first quantum barrier layer.

The nitride-based light emitting device according to claim 1, wherein the second quantum barrier layer has a thickness of 0.2 to 5 nm.

The nitride-based light emitting device of claim 1, wherein the quantum well structure comprises eight.

The nitride-based light emitting device according to claim 1, wherein at least one of the first quantum barrier layers comprises an n-type dopant.

The nitride-based light emitting device of claim 1, wherein at least one of the quantum well layers comprises an n-type dopant.

The nitride-based light emitting device of claim 1, further comprising a second stress relaxation layer between the quantum well layer and the first quantum barrier layer.

The nitride-based light emitting device according to claim 13, wherein the second stress relaxation layer has a superlattice structure.

The nitride-based light emitting device according to claim 13, wherein the second stress relaxation layer has a structure in which gallium nitride and indium gallium nitride are repeated.