KR20170028200A - Light emitting diode using recombination of deep level electron and method of fabricating the same - Google Patents

Light emitting diode using recombination of deep level electron and method of fabricating the same Download PDF

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KR20170028200A
KR20170028200A KR1020150125149A KR20150125149A KR20170028200A KR 20170028200 A KR20170028200 A KR 20170028200A KR 1020150125149 A KR1020150125149 A KR 1020150125149A KR 20150125149 A KR20150125149 A KR 20150125149A KR 20170028200 A KR20170028200 A KR 20170028200A
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light
layer
active region
type contact
contact layer
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KR1020150125149A
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Korean (ko)
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최효식
한창석
김화목
허정훈
장창근
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서울바이오시스 주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials
    • H01L33/504—Elements with two or more wavelength conversion materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/12—Passive devices, e.g. 2 terminal devices
    • H01L2924/1204—Optical Diode
    • H01L2924/12041—LED

Abstract

The present invention provides a light emitting diode (LED) using recombination of a deep level electron and a manufacturing method thereof. According to one embodiment of the present invention, the LED comprises: an n-type contact layer; a p-type contact layer; a first active region interposed between the n-type and p-type contact layers to generate light of an ultraviolet range; a second active region interposed between the first active region and the p-type contact layer to generate light of a blue range; and at least one gallium nitride-based light absorption-emission layer disposed on the n-type contract layer by facing the first active region, and absorbing a part of the light emitted from the first active region to emit light of a yellow range. According to the present invention, an LED using the light absorption-emission layer to realize white light without a fluorescent body can be provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light emitting diode (LED) using deep-level electrons and a method of manufacturing the same.

The present invention relates to an inorganic semiconductor light-emitting diode and a method of manufacturing the same, and more particularly, to a light-emitting diode using deep-level electron recombination and a method of manufacturing the same.

In general, gallium nitride based semiconductors are widely used in ultraviolet light, blue / green light emitting diodes or laser diodes as light sources for full color displays, traffic lights, general illumination and optical communication devices.

White light is required for various applications such as display and general illumination, and a light emitting diode can be used as a light source of white light. As a method for realizing white light, a method of combining blue or ultraviolet light emitting diodes and phosphors has been widely used. For example, white light can be realized by combining a blue light emitting diode and a yellow phosphor. However, since a phosphor is combined with a light emitting diode through a separate process after fabricating a light emitting diode chip, the process becomes complicated.

Alternatively, it is possible to provide light emitting diodes that emit white light without phosphors by disposing active regions that emit light of different wavelength regions in one chip. However, it is not easy to grow active regions having different compositions to have a good crystal quality on a single growth substrate. Furthermore, since these active regions are supplied with current through different current supply lines, the process of forming electrodes on the light emitting diode is very complicated.

On the other hand, deep level traps in the gallium nitride based semiconductor layer are well known. Refer to Applied Physics Letters 71 (22) (Appl. Phys. Lett., 71 (22), December 1, 1997) for the deep level of the gallium nitride based semiconductor layer. These deep level traps are generated by crystal defects and have a energy level of approximately 2.2 eV in the GaN layer, which is a source of light in the yellow region. The prior art has evolved to remove deep levels and there has been no attempt to exploit this.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting diode capable of emitting yellow light by recombination of deep level electrons to the outside.

Another object of the present invention is to provide a light emitting diode capable of realizing white light using the yellow light.

Another object of the present invention is to provide a light emitting diode having an active region of good crystal quality.

According to an embodiment of the present invention, an n-type contact layer; a p-type contact layer; A first active region interposed between the n-type contact layer and the p-type contact layer to generate light in an ultraviolet region; A second active region interposed between the first active region and the p-type contact layer to generate light in the blue region; And at least one gallium nitride-based light absorbing-emitting layer located on the side of the n-type contact layer opposite to the first active region and absorbing part of the light emitted from the first active region to emit light in the yellow region Emitting diode is provided.

According to another embodiment of the present invention, there is provided a semiconductor device comprising: an n-type contact layer; a p-type contact layer; A first active region interposed between the n-type contact layer and the p-type contact layer to generate light in an ultraviolet region; A second active region interposed between the first active region and the p-type contact layer to generate light in the blue region; And a gallium nitride based light absorption-emitting layer which is positioned between the n-type contact layer and the first active region and absorbs a part of light emitted from the first active region to emit light in a yellow region, / RTI >

According to another embodiment of the present invention, there is provided a method for growing a gallium nitride-based light absorbing-emitting layer on a growth substrate, comprising the steps of: forming an n-type contact layer, a first active region, Type contact layer is grown. Here, the first active region emits light in the ultraviolet region, the second active region emits light in the blue region, and the light absorption-emissive layer absorbs a portion of the light emitted from the first active region And emits light in the yellow region.

According to another embodiment of the present invention, an n-type contact layer is grown on a growth substrate, a light absorption-emissive layer is grown on the n-type contact layer, and a first active region , A second active region, and a p-type contact layer. Here, the first active region emits light in the ultraviolet region, the second active region emits light in the blue region, and the light absorption-emissive layer absorbs a portion of the light emitted from the first active region And emits light in the yellow region.

According to embodiments of the present invention, the gallium nitride based light absorbing-emitting layer can absorb light emitted from the first active region and emit light in the yellow region by recombination of deep level electrons. Since the light in the yellow region is emitted without the phosphor, by using the light in the yellow region, it is possible to realize a light emitting diode that emits white light without a phosphor. Further, since ultraviolet rays generated in the first active region are absorbed by the light absorption-emitting layers and the second active region, ultraviolet rays emitted to the outside can be blocked.

1 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a principle of light emission of a light emitting diode according to an embodiment of the present invention.
3 is an energy band diagram for explaining the light emission principle of a light emitting diode according to an embodiment of the present invention.
4 is an energy band diagram for explaining the recombination of level electrons of a light emitting diode according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, and the like of components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

A light emitting diode according to an embodiment of the present invention includes an n-type contact layer; a p-type contact layer; A first active region interposed between the n-type contact layer and the p-type contact layer to generate light in an ultraviolet region; A second active region interposed between the first active region and the p-type contact layer to generate light in the blue region; And at least one gallium nitride-based light absorbing-emitting layer located on the side of the n-type contact layer opposite to the first active region and absorbing part of the light emitted from the first active region to emit light in the yellow region .

According to an embodiment of the present invention, light in the yellow region emitted from the gallium nitride-based light absorption-emitting layer can be used together with light emitted from the second active region. Therefore, the light in the yellow region can be emitted without the phosphor. Further, the second active region uses a common electrode together with the first active region, and the light absorbing-emitting layer is not driven by electrical energy but absorbs light generated in the active region to generate light of a new wavelength Release. Therefore, the light emitting diode according to the present embodiment can be driven by two electrodes, unlike a light emitting diode having a plurality of active regions which are individually driven individually, and the manufacturing process thereof is extremely simple.

Meanwhile, the light emitting diode emits light in the blue region and light in the yellow region. Since the blue component and the yellow component can be provided from the gallium nitride layers in the light emitting diode, the light emitting diode can emit a mixed color light, for example, white light without separately bonding the phosphor.

In the embodiments of the present invention, the light in the yellow region is generated by recombination of deep level electrons of the light absorption-emitting layer. Refer to Applied Physics Letters 71 (22) (Appl. Phys. Lett., 71 (22), December 1, 1997) for the deep level of the gallium nitride based semiconductor layer. The recombination of deep level electrons is created by defects in GaN-based crystals, embodiments of the present invention utilize light in the yellow region generated by recombination of deep level electrons. Further, by setting the light emitted from the second active region to light of a specific region, it is possible to realize light of a specific color, for example, white light, which can be observed from the outside with naked eyes.

In some embodiments, the first active region may comprise a gallium nitride based quantum well layer that emits ultraviolet light having an emission peak in the range of 360 nm to 385 nm. In addition, the second active region may comprise a gallium nitride based quantum well layer that emits blue light having an emission peak in the range of 400 nm to 450 nm. Thus, the energy band gap of the quantum well layer in the second active region will be less than the energy band gap of the quantum well layer in the first active region.

On the other hand, the first active region and the second active region each include a quantum barrier layer. Since the electron mobility is larger than the hole mobility, it is necessary to reinforce the movement of holes while suppressing the movement of electrons. By controlling the thickness of the quantum barrier layer, the movement of electrons and holes can be controlled. In some embodiments, the quantum barrier layer of the first active region may be thicker than the quantum barrier layer of the second active region. The quantum well layers of the first active region and the second active region may also have different thicknesses. For example, the thickness of the quantum well layer of the first active region may be greater than the thickness of the quantum well layer of the second active region.

In the first and second active regions, the energy bandgap of each quantum barrier layer is greater than the energy bandgap of the adjacent quantum well layer, but the energy band gap of the adjacent quantum well layer does not exceed 2 eV Band gap. By this condition, lattice mismatch between the quantum barrier layer and the quantum well layer can be alleviated, and the crystal quality of the active regions can be improved.

The first active region and the second active region may comprise a quantum well layer of AlxInyGazN (where 0? X <1, 0 <y <1, 0 <z <1) (0? U <1, 0? V <1, 0? W? 1). The composition ratios of Al, In and Ga are adjusted to control the energy band gap of the first and second active regions and the light absorption-emitting layer. In particular, the energy band gap of the light absorption-emitting layer has a value close to the energy band gap of the first active region such that a part of the light emitted from the first active region is absorbed in the light absorption-emitting layer.

Meanwhile, the n-type contact layer and the p-type contact layer each have an energy band gap wider than the energy band gap of the quantum well layer of the second active region. Thus, the light emitted in the second active region passes through the n-type contact layer and the p-type contact layer. Furthermore, the n-type contact layer and the p-type contact layer have an energy band gap wider than the energy band gap of the quantum well layer of the first active region and can transmit ultraviolet rays emitted from the first active region.

In some embodiments, the light absorption-emissive layer may have a higher Si doping concentration than the n-type contact layer. The Si doping concentration may be, for example, in the range of 1.5E19 / cm3 to 1E21 / cm3.

In some embodiments, the light emitting diode is disposed between the n-type contact layer and the first active region and absorbs a portion of the light emitted from the first active region to form a second light absorption - emissive layer. Since the second light absorbing-emitting layer is located closer to the first active region than the n-type contact layer, the conversion rate of light emitted from the first active region can be improved.

Furthermore, the light emitting diode may further include a superlattice layer interposed between the second light absorption-emitting layer and the first active region. By arranging the superlattice layer, the crystal quality of the first active region can be improved.

In some embodiments, the light emitting diode may further include a growth substrate. The at least one light absorbing-emitting layer is interposed between the growth substrate and the n-type contact layer. The growth substrate is not particularly limited as long as it is a substrate on which the gallium nitride based semiconductor layer can be grown. For example, a sapphire substrate or a patterned sapphire substrate. Furthermore, a buffer layer may be interposed between the growth substrate and the light absorption / emission layer.

A light emitting diode according to another embodiment includes an n-type contact layer; a p-type contact layer; A first active region interposed between the n-type contact layer and the p-type contact layer to generate light in an ultraviolet region; A second active region interposed between the first active region and the p-type contact layer to generate light in the blue region; And a gallium nitride based light absorbing-emitting layer which is located between the n-type contact layer and the first active region and absorbs a part of light emitted from the first active region to emit light in a yellow region.

According to the above embodiment, light in the yellow region emitted from the gallium nitride-based light absorption-emitting layer can be used together with light emitted from the second active region. Therefore, the light in the yellow region can be emitted without the phosphor. Further, the second active region uses a common electrode together with the first active region, and the light absorbing-emitting layer is not driven by electric energy but absorbs light generated in the first active region, And emits light. Therefore, the light emitting diode according to the present embodiment can be driven by two electrodes, unlike a light emitting diode having a plurality of active regions which are individually driven individually, and the manufacturing process thereof is extremely simple. Furthermore, since the light absorbing-emitting layer is disposed between the first active region and the n-type contact layer, ultraviolet rays generated in the first active region are absorbed in the light absorbing-emitting layer before passing through the n-type contact layer. Therefore, in the light emitting diode according to the present embodiment, the ultraviolet ray absorptivity of the light absorption-emissive layer is increased, so that the light amount of the yellow region can be increased.

The light emitting diode may further include a superlattice layer interposed between the light absorption-emitting layer and the first active region. By arranging the superlattice layer, it is possible to prevent crystal defects generated in the light absorption-emitting layer from being transferred to the first active region, thereby improving the crystal quality of the first active region.

A method for fabricating a light emitting diode according to another embodiment of the present invention includes growing a gallium nitride based light absorbing-emitting layer on a growth substrate, forming an n-type contact layer, a first active region, 2 active region and a p-type contact layer. Here, the first active region emits light in the ultraviolet region, the second active region emits light in the blue region, and the light absorption-emissive layer absorbs a portion of the light emitted from the first active region And emits light in the yellow region.

Since the light absorption-emitting layer is formed of a gallium nitride compound, it can be easily formed using a conventional gallium nitride semiconductor layer growth technique, for example, MOCVD. Further, the n-type contact layer, the first and second active regions, and the p-type contact layer can also be grown as a gallium nitride-based semiconductor layer, and the light absorption-emitting layer and these layers can be continuously grown without breaking the vacuum.

Meanwhile, the light emitting diode emits light in the blue region and light in the yellow region. Since the blue component and the yellow component can be provided from the gallium nitride layers in the light emitting diode, the light emitting diode can emit a mixed color light, for example, white light without separately bonding the phosphor.

In the embodiments of the present invention, the light in the yellow region is generated by recombination of deep level electrons of the light absorption-emitting layer. The recombination of deep level electrons is created by defects in GaN-based crystals, embodiments of the present invention utilize light in the yellow region generated by recombination of deep level electrons. Further, by setting the light emitted from the second active region to light of a specific region, it is possible to realize light of a specific color, for example, white light, which can be observed from the outside with naked eyes.

In some embodiments, the light absorption-emissive layer can be grown at a temperature lower than the growth temperature of the n-type contact layer. For example, the n-type contact layer may be grown at a temperature of at least 1000 캜, while the light absorption-emissive layer may be grown at a temperature in the range of 700 캜 to 900 캜. The deep level can be generated by defects created therein by growing the light absorption-emissive layer at a relatively low temperature.

In yet other embodiments, the light absorption-emissive layer may have a higher Si doping concentration than the Si doping concentration in the n-type contact layer. The deep level can be generated by defects caused by overpoting of Si.

In some embodiments, the method of fabricating the light emitting diode may further comprise forming a second light absorption-emissive layer on the n-type contact layer prior to growing the first active region. Furthermore, the light emitting diode manufacturing method may further include forming a superlattice layer on the second light absorption-emissive layer. The first active region may be grown on the superlattice layer.

A method of fabricating a light emitting diode according to another embodiment of the present invention includes growing an n-type contact layer on a growth substrate, growing a light absorption-emissive layer on the n-type contact layer, Lt; RTI ID = 0.0 &gt; a &lt; / RTI &gt; first active region, a second active region and a p-type contact layer. Here, the first active region emits light in the ultraviolet region, the second active region emits light in the blue region, and the light absorption-emissive layer absorbs a portion of the light emitted from the first active region And emits light in the yellow region.

Since the light absorption-emitting layer is formed of a gallium nitride compound, it can be easily formed using a conventional gallium nitride semiconductor layer growth technique, for example, MOCVD. Further, the n-type contact layer, the first and second active regions, and the p-type contact layer can also be grown as a gallium nitride-based semiconductor layer, and the light absorption-emitting layer and these layers can be continuously grown without breaking the vacuum.

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

1 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.

1, the light emitting diode includes a first light absorbing-emitting layer 27a and / or a second light absorbing-emitting layer 27b, an n-type contact layer 29, a first active region 33, 2 active region 35 and a p-type contact layer 39, Further, the light emitting diode may include a growth substrate 21, a buffer layer 23, a gallium nitride semiconductor layer 25, an electronic block layer 37, an n-electrode 41 and a p-electrode 43 . In addition, although not shown in the drawings, the light emitting diodes may be added between the upper layers as needed.

The growth substrate 21 is a substrate for growing a gallium nitride based semiconductor layer, and is not particularly limited. For example, the growth substrate 21 may be a flat sapphire substrate or a patterned sapphire substrate (PSS), SiC, spinel, or the like. Here, although the light emitting diode is shown as including the growth substrate 21, the growth substrate 21 may be removed from the light emitting diode.

The buffer layer 23 is a layer for relieving the occurrence of defects such as dislocation between the substrate 21 and the n-type contact layer 29. The buffer layer 23 has a thickness of about 1.5 占 퐉, for example, Can be grown on the growth substrate 21. Although not shown, the buffer layer 23 is formed on the growth substrate 21 by using MOCVD (Metal-Organic Chemical Vapor Deposition) technology to a thickness of about 25 nm (Al, Ga) As shown in FIG. The gallium nitride based semiconductor layers described below can also be grown using the MOCVD technique, as well as the buffer layer 23, unless otherwise specified.

The gallium nitride based semiconductor layer 25 is grown on the buffer layer 23 and may not intentionally doping the impurity or may be doped with Si as an impurity. The Si doping concentration is similar to or lower than the n-type contact layer 29. The gallium nitride semiconductor layer 25 can be grown at a temperature of 1000 캜 or higher with (Al, In, Ga) N.

The first light absorption-emitting layer 27a is formed of a gallium nitride-based semiconductor layer. For example, the first light absorption-emitting layer 27a may be formed of AluInvGawN (where 0? U <1, 0? V <1, 0? W? 1). The first light absorbing-emitting layer 27a has a number of deep level traps. The deep level traps in the gallium nitride based semiconductor layer correspond to the energy of light in the yellow region, for example, the deep level energy level in the GaN layer is about 2.2 eV. The thickness of the first light absorbing-emitting layer 27a is not particularly limited, and may be, for example, in the range of 5 nm to 100 nm.

In one embodiment, the first light absorbing-emitting layer 27a is formed on the growth substrate 21 Lt; RTI ID = 0.0 &gt; 700 C &lt; / RTI &gt; In particular, the first light absorption-emitting layer 27a can be grown at a temperature lower than its growth temperature on a layer grown at a relatively high temperature, for example, a gallium nitride-based semiconductor layer 25. [ Growing the gallium nitride layer at relatively low temperatures can cause defects in the grown layer, thereby increasing deep level traps.

In yet another embodiment, the first light absorbing-emitting layer 27a may have an over-doped Si doping concentration. In this case, the first light absorption-emitting layer 27a may be grown at a relatively low temperature as described above, but grown at a temperature similar to or higher than that of the gallium nitride based semiconductor layer 25. [ The Si doping concentration in the first light absorption-emitting layer 27a is typically significantly higher than the concentration doped in the n-type contact layer 29, and may be in the range, for example, from 1.5E19 / cm3 to 1E21 / cm3.

The first light absorption-emitting layer 27a has an energy band gap due to the gallium nitride-based semiconductor layer and also has a deep level. The first light absorption-emitting layer 27a absorbs light of energy higher than the energy bandgap of the gallium nitride-based semiconductor layer and emits light to the outside by recombination of deep-level electrons.

The n-type contact layer 29 is formed of an n-type impurity, for example, a gallium nitride-based semiconductor layer doped with Si, and may be formed to a thickness of about 1 to 3 m, for example. The n-type contact layer 29 has a bandgap wider than the energy bandgap of the quantum well layers of the first and second active regions 33 and 35 and may include, for example, a GaN layer, an AlGaN layer or an AlInGaN layer . The n-type contact layer 29 may be formed as a single layer or a multilayer, and may include a superlattice structure.

The n-type contact layer 29 is grown on the first light absorption-emitting layer 27a at a temperature of about 1000 캜 or higher. On the other hand, since the first light absorbing-emitting layer 27a includes a relatively high concentration of defects, it is preferable to form the first light absorbing-emitting layer 27a on the first light absorbing- Based crystalline recovery layer (not shown) of the same or similar composition as the first light absorption-emitting layer 27a may be grown at a high temperature. emitting layer 27a is disposed between the n-type contact layer 29 and the growth substrate 21 since the n-type contact layer 29 is grown on the first light absorption-emitting layer 27a. do. Although a single first light absorbing-emitting layer 27a is shown in the figure, a plurality of light absorbing-emitting layers 27a may be disposed between the growth substrate 21 and the n-type contact layer 29 .

On the other hand, the second light absorbing-emitting layer 27b is formed of a gallium nitride based semiconductor layer having the same or similar composition as the first light absorbing-emitting layer 27a. For example, the second light absorbing-emitting layer 27b may be formed of AluInvGawN (where 0? U <1, 0? V <1, 0? W? 1). However, the second light absorbing-emitting layer 27b need not necessarily be the same composition as the first light absorbing-emitting layer 27a.

The second light absorption-emitting layer 27b has a number of deep level traps, similar to the first light absorption-emitting layer 27a. The deep level traps in the gallium nitride based semiconductor layer correspond to the energy of light in the yellow region, for example, the deep level energy level in the GaN layer is about 2.2 eV. The thickness of the second light absorbing-emitting layer 27b is not particularly limited, and may be, for example, in the range of 5 nm to 100 nm.

The second light absorbing-emitting layer 27b is formed on the n-type contact layer 29 Lt; RTI ID = 0.0 &gt; 700 C &lt; / RTI &gt; In particular, the second light absorbing-emitting layer 27b may be grown at a temperature lower than its growth temperature on the n-type contact layer 29 grown at a relatively high temperature. Growing the gallium nitride layer at relatively low temperatures can cause defects in the grown layer, thereby increasing deep level traps.

In yet another embodiment, the second light absorbing-emitting layer 27b may have an over-doped Si doping concentration. In this case, the second light absorbing-emitting layer 27b may be grown at a relatively low temperature as described above, but grown at a temperature similar to or higher than the n-type contact layer 29. The Si doping concentration in the second light absorption-emissive layer 27b is typically significantly higher than the concentration doped in the n-type contact layer 29, and may be in the range, for example, from 1.5E19 / cm3 to 1E21 / cm3.

The second light absorption-emitting layer 27b has an energy band gap by the gallium nitride-based semiconductor layer, and also has a deep level. The second light absorption-emitting layer 27b absorbs light of energy higher than its energy bandgap and emits light in the yellow region by recombination of deep-level electrons.

The superlattice layer 31 is formed before the growth of the first active region 33 to improve the crystal quality of the first active region 33 to be formed thereon. In particular, the superlattice layer 31 is formed on the second light absorbing-emitting layer 27b to recover the crystallinity deteriorated by the second light absorbing-emitting layer 27b.

The superlattice layer 31 may be formed by laminating a first AlInGaN layer and a second AlInGaN layer having different compositions, for example, in a thickness of 20 angstroms alternately, for example, about 30 periods. The first AlInGaN layer and the second AlInGaN layer have a relatively wide bandgap relative to the quantum well layers in the first and second active regions 33 and 35. [ The In composition ratio contained in the first AlInGaN layer and the second AlInGaN layer may be smaller than the In composition ratio contained in the quantum well layers but is not limited thereto and at least one of the first AlInGaN layer and the second AlInGaN layer may be a quantum well It may have an In composition ratio higher than that of the well layer. The superlattice layer 31 may be intentionally formed as an undoped layer without doping the impurity. Since the superlattice layer 31 is formed as an undoped layer, the leakage current of the light emitting device can be reduced.

The first active region 33 and the second active region 33 and 35 are disposed between the n-type contact layer 29 and the p-type contact layer 39. In particular, the first active region 33 and the second active region 33, 35 may be disposed on the second light absorbing-emitting layer 27b, and thus the light absorbing-emitting layer 27b may be disposed on the first And is disposed between the active region 33 and the n-type contact layer 29.

The first active region 33 may be grown on the superlattice layer 31. The first active region 33 includes a quantum barrier layer and a quantum well layer. The first active region 33 may have a single quantum well structure, but it may have a multiple quantum well structure in which quantum barrier layers and quantum well layers are alternately stacked. A second active region 35 is grown on the first active region 33. The second active region 35 may also have a single bipolar well structure or a multiple quantum well structure.

The first active region 33 may comprise a gallium nitride based quantum well layer that emits ultraviolet light having an emission peak in the range of 360 nm to 385 nm and the second active region 35 may comprise a GaN- And a gallium nitride-based quantum well layer that emits blue light having an emission peak. The energy band gap of the quantum well layer in the second active region 33 is smaller than the energy band gap of the quantum well layer in the first active region 35. [ The quantum well layers of the first active region 33 and the second active region 35 may be formed of AlxInyGazN (where 0? X <1, 0 <y <1, 0 <z <1).

On the other hand, the first active region 33 and the second active region 35 each include a quantum barrier layer. The quantum barrier layers may be formed of a gallium nitride-based semiconductor layer having a larger band gap than the adjacent quantum well layers, for example, GaN, InGaN, AlGaN, or AlInGaN. In particular, the quantum barrier layers can be formed of AlInGaN, which can mitigate lattice mismatch between the quantum well layer and the quantum barrier layer by including In.

In some embodiments, the quantum barrier layer of the first active region 33 may be thicker than the quantum barrier layer of the second active region 35. The quantum well layers of the first active region 33 and the second active region 35 may also have different thicknesses. For example, the thickness of the quantum well layer of the first active region 33 may be greater than the thickness of the quantum well layer 35 of the second active region.

Further, in the first and second active regions 33 and 35, the energy band gap of each quantum barrier layer may have an energy band gap not greater than the energy band gap of the adjacent quantum well layer by 2 eV. The lattice mismatch between the quantum barrier layer and the quantum well layer can be alleviated by this condition, and the crystal quality of the active regions 33 and 35 can be improved.

On the other hand, the first and second light absorbing-emitting layers 27a, 27b (27a, 27b) are formed so that a part of the light emitted from the first active region 33 is absorbed in the first and / Has a value close to the energy bandgap of the quantum well layers of the first active region 33. [ For example, the energy bandgap of the quantum well layers of the first active region 33 may have a value in the range of 3.1 eV to 3.45 eV, and the first and second light absorbing-emitting layers 27a and 27b may have a value of 2.95 eV to 3.65 eV. &lt; / RTI &gt;

Part of the light emitted from the first active region 33 has an energy larger than the energy band gap of the light absorption-emitting layers 27a and 27b. Accordingly, a part of the light emitted from the first active region 33 can be absorbed by the first and / or second light absorption-emitting layers 27a and 27b to generate free electrons. Some of these free electrons are trapped in the deep level trap and recombine with the holes to produce light in the yellow region.

The p-type contact layer 39 is located on the second active region 35. On the other hand, the electron blocking layer 37 may be positioned between the second active region 35 and the p-type contact layer 39. [ The electron blocking layer 37 may be formed of AlGaN or AlInGaN. When formed with AlInGaN, the lattice mismatch with the second active region 35 can be further mitigated. At this time, the electron blocking layer 37 has an Al content higher than that of the barrier layer 31. The electron blocking layer 37 may be doped with a p-type impurity, such as Mg, but may not intentionally doping impurities. The electron blocking layer 37 may be formed to a thickness of about 15 nm.

The p-type contact layer 39 may be formed of a Mg-doped GaN layer, an AlGaN layer, or an AlInGaN layer, and the thickness may be about 100 nm. The p-type contact layer 39 may be formed of a single layer, but not limited thereto, and may be formed of multiple layers. Furthermore, the p-type contact layer 39 is not limited to the gallium nitride based semiconductor layer but may be formed of other kinds of compound semiconductors.

On the other hand, the n-electrode 41 and the p-electrode 43 are in electrical contact with the n-type contact layer 29 and the p-type contact layer 39, respectively. These electrodes 41 and 43 are formed from the outside in order to supply current to the first and second active regions 33 and 35. It should be noted here that the first light absorbing-emitting layer 27a is disposed outside the path of the current supplied from these electrodes 41 and 43. [ That is, the first light absorption-emitting layer 27a is located on the side of the n-type contact layer 29 opposite to the first active region 33. [ Alternatively, the second light absorbing-emitting layer 27b is located between the first active region 33 and the n-type contact layer 29.

FIGS. 2 to 4 are cross-sectional views and energy band diagrams for explaining the light emission principle of a light emitting diode according to an embodiment of the present invention, respectively.

2 and 3, when current is supplied through the n-electrode 41 and the p-electrode 43, ultraviolet light (NUV) is generated in the quantum well layers in the first active region 33 And the blue region of light B1 in the quantum well layers in the second active region 35 is generated. The light B1 in the blue region will be emitted to the outside.

On the other hand, since the energy band gap of the second active region 35 is narrower than that of the first active region 33, a part of the ultraviolet ray NUV is absorbed in the second active region 35 as it advances to the upper side of the light emitting diode . The light absorbed in the second active region 35 excites the electrons of the quantum well layer in the second active region 35 to generate free electrons which recombine with the holes again to form blue light B2, . And the light B2 in the blue region is emitted to the outside of the light emitting diode.

A part of the ultraviolet ray (NUV) proceeds to the lower side of the light emitting diode (in the direction of the growth substrate 21). A part of this ultraviolet ray (NUV) is absorbed again in the first light absorbing-emitting layer 27a and / or the second light absorbing-emitting layer 27b.

4, the energy band gap Eg of the first and second light absorbing-emitting layers 27a and 27b is set to absorb a part of the ultraviolet light NUV generated in the first active region 33 do. Accordingly, the ultraviolet light NUV excites electrons below the valence band in the first and second light absorption-emitting layers 27a and 27b to generate free electrons. Part of the free electrons will recombine with the holes to emit light corresponding to the energy band gap Eg of the first or second light absorption-emitting layer 27a or 27b to the outside. However, if the first and / or second light absorbing-emitting layer 27a, 27b have a significant amount of deep level (DL) traps, a significant number of free electrons are trapped at the deep level DL, And recombines with the holes to emit light (Y1, Y2) in the yellow region. The light (Y1, Y2) in the yellow region is emitted to the outside of the light emitting diode. Refer to Applied Physics Letters 71 (22) (Appl. Phys. Lett., 71 (22), December 1, 1997) for light in the yellow region emitted by recombination of deep level electrons in the gallium nitride based semiconductor layer .

Referring again to FIG. 2, light (B 1, B 2) in the blue region generated in the second active region 35 and light (B 1, B 2) in the blue region generated in the first and / or second light absorption- The lights Y1 and Y2 are emitted to the outside, and a mixed color light, for example, white light, can be observed from the outside by a combination of lights.

The light emitting diode described above can be used in a package form. The light emitting diode may be molded with a silicone resin or the like or sealed with a transparent lens. In addition, the light emitting diode package can be mounted on a printed circuit board to constitute a light emitting module.

On the other hand, a part of the ultraviolet light (NUV) may be emitted to the outside of the light emitting diode. This ultraviolet ray (NUV) can be used in the technical field using ultraviolet rays, for example, for counterfeiting, resin hardening and ultraviolet ray treatment.

On the other hand, if ultraviolet light (NUV) is not required, techniques for preventing ultraviolet rays from being emitted to the outside can be used. For example, when fabricating the above-described package of the light emitting diode, a lens for blocking light of 400 nm or less or a lens having a band-pass filter function can be mounted on the package.

21 growth substrate
23 buffer layer
25 n-type gallium nitride-based semiconductor layer
27a First light absorption-emitting layer
27b Second light absorption-emitting layer
29 n-type contact layer
31 second lattice layer
33 first active area
35 second active area
37 electronic block layer
39 p-type contact layer
41 n- electrode
43 p-electrode
e electron
h hole (hole)

Claims (20)

an n-type contact layer;
a p-type contact layer;
A first active region interposed between the n-type contact layer and the p-type contact layer to generate light in an ultraviolet region;
A second active region interposed between the first active region and the p-type contact layer to generate light in the blue region; And
And at least one gallium nitride-based light absorbing-emitting layer located on the side of the n-type contact layer opposite to the first active region and absorbing part of the light emitted from the first active region to emit light in the yellow region Lt; / RTI &gt; The method according to claim 1,
The light emitting diode emits white light,
Wherein the white light includes the light in the yellow region and the light in the blue region. The method according to claim 1,
Wherein light in the yellow region is generated by recombination of deep level electrons of the light absorption-emitting layer. The method according to claim 1,
Wherein the first active region comprises a gallium nitride based quantum well layer that emits ultraviolet light having an emission peak in the range of 360 nm to 385 nm,
And the second active region comprises a gallium nitride based quantum well layer that emits blue light having an emission peak in the range of 400 nm to 450 nm. The method of claim 4,
Wherein the first active region and the second active region comprise a quantum well layer of AlxInyGazN (0? X <1, 0 <y <1, 0 <z <
Emitting layer is formed of AluInvGawN (with 0? U <1, 0? V <1, 0? W? 1). The method of claim 5,
Wherein the n-type contact layer and the p-type contact layer each have an energy band gap wider than the energy band gap of the quantum well layer. The method according to claim 1,
Wherein the light absorption-emitting layer has a higher Si doping concentration than the n-type contact layer. The method according to claim 1,
And a second light absorbing-emitting layer disposed between the n-type contact layer and the first active region to absorb a portion of the light emitted from the first active region and emit light in the yellow region. The method of claim 8,
And a superlattice layer interposed between the second light absorbing-emitting layer and the first active region. The method according to claim 1,
Further comprising a growth substrate,
Wherein the at least one light absorbing-emitting layer is interposed between the growth substrate and the n-type contact layer. an n-type contact layer;
a p-type contact layer;
A first active region interposed between the n-type contact layer and the p-type contact layer to generate light in an ultraviolet region;
A second active region interposed between the first active region and the p-type contact layer to generate light in the blue region; And
And a gallium nitride based light absorbing-emitting layer disposed between the n-type contact layer and the first active region and absorbing a part of light emitted from the first active region to emit light in a yellow region. The method of claim 11,
And a superlattice layer interposed between the light absorption-emitting layer and the first active region. A gallium nitride based light absorption-emitting layer is grown on a growth substrate,
And growing an n-type contact layer, a first active region, a second active region and a p-type contact layer on the light absorption-emitting layer,
Wherein the first active region emits light in the ultraviolet region, the second active region emits light in the blue region, and the light absorbing-emitting layer absorbs a portion of the light emitted from the first active region, Emitting diode. 14. The method of claim 13,
Wherein the light emitting diode emits white light, and the white light includes light in the blue region and light in the yellow region. 14. The method of claim 13,
Wherein the light in the yellow region is generated by recombination of deep level electrons of the light absorbing-emitting layer. 16. The method of claim 15,
Emitting layer is grown at a temperature lower than the growth temperature of the n-type contact layer. 16. The method of claim 15,
Wherein the light absorption-emitting layer has a Si doping concentration higher than the Si doping concentration in the n-type contact layer. 14. The method of claim 13,
Further comprising forming a light absorption-emissive layer on the n-type contact layer before growing the first active region. 19. The method of claim 18,
Further comprising forming a superlattice layer on the light absorption-emissive layer, wherein the first active region is grown on the superlattice layer. An n-type contact layer is grown on the growth substrate,
Emitting layer is grown on the n-type contact layer,
And growing a first active region, a second active region and a p-type contact layer on the light absorption-emitting layer,
Wherein the first active region emits light in the ultraviolet region, the second active region emits light in the blue region, and the light absorbing-emitting layer absorbs a portion of the light emitted from the first active region, Emitting diode.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20180136053A (en) * 2017-06-14 2018-12-24 엘지이노텍 주식회사 Semiconductor device and Semiconductor device package

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20180136053A (en) * 2017-06-14 2018-12-24 엘지이노텍 주식회사 Semiconductor device and Semiconductor device package

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