KR20120047073A - Gallium nitride-based compound semiconductor light-emitting device - Google Patents

Gallium nitride-based compound semiconductor light-emitting device Download PDF

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KR20120047073A
KR20120047073A KR1020100108747A KR20100108747A KR20120047073A KR 20120047073 A KR20120047073 A KR 20120047073A KR 1020100108747 A KR1020100108747 A KR 1020100108747A KR 20100108747 A KR20100108747 A KR 20100108747A KR 20120047073 A KR20120047073 A KR 20120047073A
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layer
gan
emitting device
gallium nitride
light emitting
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KR1020100108747A
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Korean (ko)
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최성철
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(주)더리즈
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers 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 having potential barriers 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 having potential barriers 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 having potential barriers 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
    • H01L33/00—Semiconductor devices having potential barriers 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 having potential barriers 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
    • H01L33/12—Semiconductor devices having potential barriers 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 stress relaxation structure, e.g. buffer layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers 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 having potential barriers 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
    • H01L33/26—Materials of the light emitting region
    • H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
    • H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Led Devices (AREA)

Abstract

A high quality gallium nitride based semiconductor light emitting device having high luminous efficiency is proposed. The proposed gallium nitride-based semiconductor light emitting device includes an active layer including a p-GaN layer, a quantum barrier layer and an InGaN quantum well layer, and a strain buffer layer containing indium in an amount higher than the indium content of the active layer on the quantum well layer, n- GaN layer, p electrode and n electrode.

Description

GALLIUM NITRIDE-BASED COMPOUND SEMICONDUCTOR LIGHT-EMITTING DEVICE}

The present invention relates to a gallium nitride-based semiconductor light emitting device, and more particularly to a high quality gallium nitride-based semiconductor light emitting device having high luminous efficiency.

A light emitting device (LED) is a device in which a material contained in the device emits light, and converts energy due to electron / hole recombination into light by bonding a semiconductor using a diode such as a light emitting diode. It is an emitting device. Such light emitting devices are widely used as lighting, display devices, and light sources, and their development is being accelerated.

In particular, with the recent commercialization of mobile phone keypads, side viewers, camera flashes, etc. using gallium nitride (GaN) -based light emitting devices that have been activated and used, general lighting development using LEDs has been vigorous. Its applications such as backlight units of large TVs, automotive headlamps, and general lighting have moved from small portable products to large size, high output, high efficiency, and reliable products, requiring light sources that exhibit the characteristics required for such products.

It is preferable that the substrate used for the GaN-based light emitting device has a similar lattice constant and thermal expansion coefficient in order to improve the crystal quality of the GaN layer. For this purpose, GaN can be grown to a substrate thickness and used as a substrate. However, since the substrate may be a growth substrate in the light emitting device or a process substrate for ease of handling in the process, the thickness of the substrate is generally several times greater than the sum of both the n-type and p-type GaN layers and the active layer thickness.

Therefore, growing GaN to the substrate thickness may be undesirable in terms of process and cost because of high melting point and high nitrogen partial pressure during growth. Therefore, in consideration of various disadvantages, it is possible to use a different substrate such as a sapphire substrate or a SiC substrate in addition to the GaN substrate.

For example, when an n-GaN layer is formed on a substrate using a sapphire substrate, defects may occur in the grown GaN due to lattice constant and thermal expansion coefficient mismatch between the substrate and the GaN layer. In addition, when an InGaN layer is grown as an active layer on an n-GaN layer, the lattice constants of the substrate, the n-GaN layer and the InGaN layer as the active layer are inconsistent, resulting in condensation strain, which makes it difficult to grow a high quality semiconductor layer as a whole. .

Therefore, development of a technique for forming a high quality InGaN layer is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a high quality gallium nitride-based semiconductor light emitting device with high luminous efficiency.

Gallium nitride-based semiconductor light emitting device according to an aspect of the present invention for achieving the above object is a p-GaN layer; an active layer including a quantum barrier layer and an InGaN quantum well layer on the p-GaN layer; A strain buffer layer containing indium in an amount higher than the indium content of the active layer on the quantum well layer; An n-GaN layer on the strain buffer layer; And a p electrode and an n electrode formed on the p-GaN layer and the n-GaN layer, respectively.

The strain buffer layer may comprise InGaN.

The indium content of the quantum well layer may be 10% to 15%, and the indium content of the strain buffer layer may be 7% to 20% or less.

The strain buffer layer may have a thickness of four to five times the thickness of the active layer.

The thickness of the quantum barrier layer may be two to three times the thickness of the quantum well layer.

The active layer may include two or more pairs of quantum barrier layers and InGaN quantum well layer.

The gallium nitride-based semiconductor light emitting device according to the present invention can minimize the strain during growth of the gallium nitride-based semiconductor layer, so that the crystal quality of the active layer that generates light is excellent, the luminous efficiency is high, high quality and reliable gallium nitride-based semiconductor light emitting device There is an effect that can be obtained.

1 is a cross-sectional view of a gallium nitride-based semiconductor light emitting device according to an embodiment of the present invention.
2 is an energy level diagram of a gallium nitride-based semiconductor light emitting device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. In the accompanying drawings, there may be a component having a specific pattern or having a predetermined thickness, but this is for convenience of description or distinction. It is not limited only.

1 is a cross-sectional view of a gallium nitride-based semiconductor light emitting device according to an embodiment of the present invention. The gallium nitride based semiconductor light emitting device 100 according to the present embodiment includes a p-GaN layer 110; an active layer 120 including a quantum barrier layer 121 and an InGaN quantum well layer 122 on the p-GaN layer 110; A strain buffer layer 130 including indium in an amount higher than the indium content of the active layer 120 on the InGaN quantum well layer 122; An n-GaN layer 140 on strain buffer layer 130; And p electrodes 150 and n electrodes 160 formed on the p-GaN layer 110 and the n-GaN layer 140, respectively.

The gallium nitride-based semiconductor light emitting device 100 according to the present exemplary embodiment emits light of a vertical structure in which a corresponding electrode is formed on a light emitting structure including an n-GaN layer 140, an active layer 120, and a p-GaN layer 110. The device has a structure that is grown on a non-conductive substrate such as sapphire (Al 2 O 3 ) or spinel (MgAl 2 O 4 ) or a SiC, Si, ZnO, GaAs, GaN substrate, and then removed.

The gallium nitride based semiconductor light emitting device 100 shown in FIG. 1 does not include a substrate, but the gallium nitride based semiconductor light emitting device according to the present invention has a structure including a conductive substrate under the n-GaN layer 140. It may be a light emitting device of. Alternatively, when the non-conductive substrate is positioned below the n-GaN layer 140, the n electrode 160 may not be positioned on the substrate, and thus may be implemented as a light emitting device having a horizontal structure.

The n-GaN layer 140 on the p-GaN layer 110 and the strain buffer layer 130 is a gallium nitride-based semiconductor layer, and the p-GaN layer 110 and the n-GaN layer 140, respectively, according to the doped impurities. Is implemented. The p-GaN layer 110 and the n-GaN layer 140 are well-known film formation methods, for example, the formation of a semiconductor layer is well-known film formation method, for example, molecular beam epitaxy (MBE) method. It may be carried out using a metal organic chemical vapor deposition (MOCVD) or a hydride vapor deposition (Hydride Vapor Phase Epitaxy, HVPE).

As the impurity of the p-GaN layer 110, it may be selected from Mg, Zn, and Be. As an impurity of the n-GaN layer 140, for example, Si, Ge, Se, Te, and C may be selected and used.

An active layer 120 that activates light emission is positioned between the p-GaN layer 110 and the n-GaN layer 140. The active layer 120 may be formed using a material having an energy band gap smaller than that of the p-GaN layer 110 and the n-GaN layer 140. Since the p-GaN layer 110 and the n-GaN layer 140 are GaN-based compound semiconductors, the active layer 120 may be formed using an InGaN-based compound semiconductor having an energy band gap less than that of the GaN-based compound semiconductors. Can be. At this time, it is preferable that the impurities are not doped due to the characteristics of the active layer 120, and the wavelength or the quantum efficiency can be adjusted by adjusting the height of the barrier, the thickness of the well layer, the composition, and the number of the wells.

When the material includes a material having a smaller energy band gap than the p-GaN layer 110 and the n-GaN layer 140, the active layer 120 may form an energy well of holes and electrons to include a quantum well layer. According to this embodiment, the InGaN-based quantum well layer 122 is used as the quantum well layer in the GaN-based compound semiconductor layer. Light emission may be activated in the active layer 120 using only the InGaN quantum well layer 122, but a quantum barrier layer 121 may be formed to form a quantum barrier around the quantum well so that electrons or holes can be maintained in the energy well enough to emit light. ) May be included. The quantum barrier layer 121 may be formed to be two to three times the thickness of the InGaN quantum well layer 122 in consideration of the electron blocking function.

The quantum barrier layer 121 may be a GaN layer, a layer in which an indium content is controlled in an InGaN layer, or a layer in which an Al or In content is controlled in an AlInGaN layer. In this embodiment, since the quantum well layer is an InGaN layer, the quantum barrier layer 121 is preferably a GaN layer. The active layer 120 may be implemented in a superlattice structure by including two or more such InGaN quantum well layers 122 / quantum barrier layers 121 as one pair.

In FIG. 1, the InGaN quantum well layer 122 is formed on the n-GaN layer 140. In general, for example, the n-GaN layer 140 is grown on a heterogeneous growth substrate such as a sapphire substrate or a SiC substrate. At this time, since the lattice constant of the heterogeneous growth substrate and the lattice constant of the n-GaN layer 140 are inconsistent, the light emitting device is subjected to a compression strain as a whole due to the growth of the n-GaN layer 140. If the active layer 120 is formed on the n-GaN layer 140 of the light emitting device in which the condensation strain is generated, since the InGaN quantum well layer 122 is a different InGaN layer from GaN, the lattice constant is inconsistent and thus receives a further condensation strain. do.

Therefore, when the lattice constant mismatch between the n-GaN layer 140 and the InGaN quantum well layer 122 is already added to the lattice constant mismatch between the substrate and the n-GaN layer 140, the light emitting device is caused by the mismatch of the lattice constant as a whole. It is subjected to condensation strain, which can cause defects in the GaN layer and the InGaN layer, resulting in poor quality.

The strain buffer layer 130 is a layer containing indium in an amount higher than the indium content of the active layer 120 on the InGaN quantum well layer 122. That is, the strain buffer layer 130 is positioned between the n-GaN layer 140 and the InGaN quantum well layer 122 to reduce the lattice constant mismatch between the n-GaN layer 140 and the InGaN quantum well layer 122. Let's do it. The strain buffer layer 130 may be an InGaN layer.

2 is an energy level diagram of a gallium nitride-based semiconductor light emitting device according to an embodiment of the present invention. Since the strain buffer layer 130 contains indium in a content higher than the total indium content of the active layer 120, the energy level is higher than that of the active layer 120, and the n-GaN layer 140 and the p-GaN layer 110 are present. And the energy level is lower than that of the quantum barrier layer 121.

The indium content of the active layer 120 means an average content of the indium content of the quantum barrier layer 121 and the InGaN quantum well layer 122. For example, if the quantum barrier layer 121 is a GaN layer and the indium content of the InGaN quantum well layer 122 is 10% to 15%, the average indium content of the active layer 120 may be 4% to 6%. . Therefore, the strain buffer layer 130 preferably has an indium content of 7% or more. The strain buffer layer 130 preferably has a higher indium content than the indium content of the active layer 120 but preferably does not exceed 20%. If the indium content of the strain buffer layer 130 exceeds 20%, the indium content may be too high and indium may aggregate in the strain buffer layer 130. When indium aggregates in the strain buffer layer 130, it may act as a defect that absorbs light.

In general, when an InGaN layer is grown on a GaN layer, the InGaN layer tends to follow the crystal lattice of the lower GaN layer. Therefore, when the InGaN quantum well layer 122 is grown on the n-GaN layer 140, the InGaN quantum well layer 122 is subjected to condensation strain because it follows the crystal lattice of the n-GaN layer 140. In addition, if there is an InGaN strain buffer layer 130 between the n-GaN layer 140 and the InGaN quantum well layer 122, the strain buffer layer 130 also follows the crystal lattice of the n-GaN layer 140 to condense strain. Will receive.

However, if the indium content of the strain buffer layer 130 includes a high concentration of indium so that it is higher than the indium content of the entire active layer 120, the difference in lattice constant between the strain buffer layer 130 and the n-GaN layer 140 becomes large. However, the difference in lattice constant between the strain buffer layer 130 and the InGaN quantum well layer 122 is smaller than the difference in lattice constant between the n-GaN layer 140 and the InGaN quantum well layer 122.

Therefore, the generation of condensation strain in the InGaN quantum well layer 122 is alleviated, so that the crystal quality of the InGaN quantum well layer 122 may be excellent. That is, the condensation deformation force due to the lattice constant mismatch with the n-GaN layer 140 is dispersed in the strain buffer layer 130, so that the condensation deformation force generated in the InGaN quantum well layer 122 is reduced, thereby improving crystal quality. . Since the crystal quality of the InGaN quantum well layer 122 is excellent, the luminous efficiency of the entire gallium nitride-based semiconductor light emitting device 100 is increased.

The thickness of the strain buffer layer 130 may be 4 to 5 times the thickness of the active layer 120. In this case, the thickness of the active layer 120 means the sum of the thicknesses of one quantum well layer and one barrier layer. Since the strain buffer layer 130 plays a role of dispersing the difference in crystal lattice constant between the active layer 120 and the n-GaN layer 140, the strain buffer layer 130 is preferably thicker than the thickness of the active layer 120. On the contrary, the strain buffer layer 130 is preferably not more than five times. If the layer having a difference in the n-GaN layer 140 and the crystal lattice constant is too thick, the strain is grown on the n-GaN layer 140. This is because the crystal quality of the buffer layer 130 itself may be degraded and the quality of the entire gallium nitride-based semiconductor light emitting device 100 may be degraded.

Since the gallium nitride-based semiconductor light emitting device 100 according to the present invention includes the strain buffer layer 130, the superlattice includes two or more pairs of InGaN quantum well layer 122 / quantum barrier layer 121 in the active layer 120. Even when the structure is implemented, two or more InGaN quantum well layers having excellent crystal quality can be formed, thereby making it possible to manufacture high quality gallium nitride-based semiconductor light emitting devices.

The p electrode 150 is formed on the p-GaN layer 110, and the n electrode 160 is formed on the n-GaN layer 140. The p electrode 150 and the n electrode 160 may be respectively connected to an external power source to apply a current to the gallium nitride based semiconductor light emitting device 100. The n-type electrode and the p-type electrode may be composed of a conductive material, for example a metal. For example, Ti may be used as the n-type electrode, and Pd or Au may be used as the p-type electrode.

The invention is not to be limited by the foregoing embodiments and the accompanying drawings, but should be construed by the appended claims. In addition, it will be apparent to those skilled in the art that various forms of substitution, modification, and alteration are possible within the scope of the present invention without departing from the technical spirit of the present invention.

100 gallium nitride semiconductor light emitting device
110 p-GaN layer
120 active layers
121 Quantum Barrier Layer
122 InGaN Quantum Well Layer
130 strain buffer layer
140 n-GaN layer
150 p electrode
160 n electrode

Claims (7)

p-GaN layer;
An active layer on the p-GaN layer, the active layer including a quantum barrier layer and an InGaN quantum well layer;
A strain buffer layer on the InGaN quantum well layer, the strain buffer layer including indium in an amount higher than the indium content of the active layer;
An n-GaN layer on the strain buffer layer; And
And a p-electrode and an n-electrode formed on the p-GaN layer and the n-GaN layer, respectively. The method according to claim 1,
The strain buffer layer is gallium nitride-based semiconductor light emitting device, characterized in that containing InGaN. The method according to claim 1,
Indium content of the InGaN quantum well layer is a gallium nitride-based semiconductor light emitting device, characterized in that 10% to 15%. The method according to claim 3,
Indium content of the strain buffer layer is a gallium nitride-based semiconductor light emitting device, characterized in that 7% to 20% or less. The method according to claim 1,
The thickness of the strain buffer layer is a gallium nitride-based semiconductor light emitting device, characterized in that 4 to 5 times the thickness of the active layer. The method according to claim 1,
The thickness of the quantum barrier layer is a gallium nitride-based semiconductor light emitting device, characterized in that two to three times the thickness of the InGaN quantum well layer. The method according to claim 1,
And said active layer comprises at least two pairs of said quantum barrier layer and said InGaN quantum well layer pair.
KR1020100108747A 2010-11-03 2010-11-03 Gallium nitride-based compound semiconductor light-emitting device KR20120047073A (en)

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