KR101876576B1 - Nitride semiconductor light emitting device and method for fabricating the same - Google Patents

Abstract

The present invention discloses a nitride semiconductor light emitting device. The nitride semiconductor light emitting device and the manufacturing method thereof according to the present invention include: a substrate; A buffer layer and an undoped semiconductor layer formed on the substrate; An N-type semiconductor layer and a P-type semiconductor layer formed on the undoped semiconductor layer; An active layer of a multiple quantum well structure interposed between the N-type semiconductor layer and the P-type semiconductor layer and having a plurality of quantum well layers and a plurality of quantum barrier layers alternately arranged; And a hole inducing layer interposed between the active layer and the P-type semiconductor layer, wherein the hole inducing layer is composed of a quantum barrier layer of the active layer and a P-type dopant diffusion layer diffused in the quantum barrier layer, Layer, the P-type dopant diffusion layer and the quantum barrier layer are sequentially lowered.
The nitride semiconductor light emitting device of the present invention is characterized in that a hole injection layer is smoothly injected into the active layer through a hole inducing layer composed of a semiconductor layer used for the quantum well layer of the active layer or a semiconductor layer diffused by the P dopant between the active layer and the P- It is effective.

Description

TECHNICAL FIELD The present invention relates to a nitride semiconductor light emitting device and a method of fabricating the same.

The present invention relates to a nitride semiconductor light emitting device, and more particularly, to a nitride semiconductor light emitting device in which a P-type dopant is diffused into a final barrier layer of an active layer to facilitate hole injection, and the light emitting efficiency is improved.

In general, nitrides of a Group III element such as gallium nitride (GaN) and aluminum nitride (AlN) used in a nitride semiconductor light emitting device have excellent thermal stability and have a direct transition type energy band structure. Recently, And are attracting much attention as materials for photoelectric elements in the ultraviolet region. In particular, blue and green light emitting devices using gallium nitride (GaN) have been used in various applications such as large-scale color flat panel displays, traffic lights, indoor lighting, high-density light sources, high resolution output systems and optical communication.

FIG. 1 illustrates a structure of a conventional nitride semiconductor light emitting device, and FIG. 2 illustrates an active layer region of the multiple quantum well structure of FIG. 1. Referring to FIG.

1 and 2, a conventional nitride semiconductor light emitting device includes a buffer layer 20 formed on an insulating substrate 10, an n-type semiconductor layer 21, an n-type semiconductor layer 21, An active layer 23, a P-type semiconductor layer 24, and a transparent metal layer 25 are stacked. An N-type electrode 27 and a P-type electrode 26 are formed on the N-type semiconductor layer 22 and the P-type semiconductor layer 24 exposed to the outside.

The insulating substrate 10 may be made of a material suitable for growing a nitride semiconductor single crystal. For example, the insulating substrate 10 may be formed using a material such as sapphire. In addition to sapphire, zinc oxide (ZnO), gallium nitride (GaN), silicon carbide, SiC), aluminum nitride (AlN), or the like.

The active layer 23 is a region where electrons and holes are recombined and has a quantum barrier layer 23a and a quantum well layer 23b expressed by a general formula of InxGa1-xN (0? X? 1) And has a quantum well structure. The emission wavelength emitted from the nitride semiconductor light emitting device is determined depending on the kind of the material forming the active layer 23. [

The active layer 23 has a single quantum well (SQW) structure having one quantum well layer and a multi quantum well (MQW) structure having a plurality of quantum well layers smaller than about 100 Å. As shown in FIG. 2, the active layer 23 of the multiple quantum well structure has a higher luminous efficiency compared with a single quantum well structure, and has a high luminous output.

The light efficiency of such a nitride semiconductor light emitting device is originally determined by the probability of recombination of electrons and holes in the active layer, that is, the internal quantum efficiency. The improvement of the internal quantum efficiency is mainly studied in order to improve the structure of the active layer itself or increase the effective mass of the carrier.

However, since the mobility of holes is generally lower than the mobility of electrons, there arises a problem that the P-type semiconductor layer 24 can not be sufficiently supplied to the active layer 23.

If holes are not sufficiently supplied to the active layer 23, electrons that do not bond among the electrons supplied from the N-type semiconductor layer 22 are generated, resulting in a decrease in luminous efficiency.

Recently, a method of forming a nano-layered structure to improve the hole injection property in the active layer has been proposed, but the growth time for forming the nano-laminated structure is long and the overall productivity is lowered.

AlGaN-based electron barrier layer formation methods have been proposed for electron overflow phenomenon and smooth injection of holes. However, aluminum (Al) acts as a contaminant source during growth of a semiconductor layer, thereby deteriorating device characteristics. In addition, an additional process is required to maintain the reactor in a high temperature state for a long time in order to form an electron barrier layer.

An object of the present invention is to provide a nitride semiconductor light emitting device having improved luminous efficiency and operating voltage by diffusing a P-type dopant in a barrier layer of a final active layer, and a method of manufacturing the same.

It is another object of the present invention to provide a nitride semiconductor light emitting device in which electrical characteristics of the device are improved through formation of a P-type dopant atmosphere for improving hole injection efficiency into the active layer and a method of manufacturing the same.

In addition, the present invention can diffuse P-type dopant to the last barrier layer of the active layer, thereby omitting the step of inserting the functional layer for increasing the hole injection efficiency into the active layer, Another object of the present invention is to provide a light emitting device and a manufacturing method thereof.

According to an aspect of the present invention, there is provided a nitride semiconductor light emitting device comprising: a substrate; A buffer layer and an undoped semiconductor layer formed on the substrate; An N-type semiconductor layer and a P-type semiconductor layer formed on the undoped semiconductor layer; An active layer of a multiple quantum well structure interposed between the N-type semiconductor layer and the P-type semiconductor layer and having a plurality of quantum well layers and a plurality of quantum barrier layers alternately arranged; And a hole inducing layer interposed between the active layer and the P-type semiconductor layer, wherein the hole inducing layer is composed of a quantum barrier layer of the active layer and a P-type dopant diffusion layer diffused in the quantum barrier layer, Layer, the P-type dopant diffusion layer and the quantum barrier layer are sequentially lowered.

The method for manufacturing a nitride semiconductor light emitting device according to the present invention includes the steps of forming a buffer layer, an unshown semiconductor layer, and an N-type semiconductor layer on a substrate; forming a plurality of quantum well layers and a plurality of quantum wells Type semiconductor layer; forming an active layer of a multi-quantum well structure in which the P-type semiconductor layer and the P-type semiconductor layer are alternately arranged; Exposing a P-type dopant to the quantum barrier layer of the active layer, and forming a hole-guiding layer of the P-type dopant diffusion layer by the P-type dopant diffused into the quantum barrier layer of the active layer, And forming a P-type semiconductor layer and a transparent electrode layer on the inductive layer.

The nitride semiconductor light emitting device and the method of manufacturing the same according to the present invention are characterized in that the energy level of the barrier layer is relatively increased by the diffusion of the P type dopant to the last barrier layer of the active layer and holes can be injected smoothly into the active layer There is a first effect of improving the luminous efficiency.

The nitride semiconductor light emitting device and the method of manufacturing the same according to the present invention have a second effect of improving the electrical characteristics of the gallium nitride based light emitting diode device by forming a P-type dopant atmosphere for improving the efficiency of hole injection into the active layer .

The nitride semiconductor light emitting device and the method of manufacturing the same according to the present invention can form a P-type dopant atmosphere in a ramping time for growing a P-type semiconductor layer after completion of growth of an active layer, There is no need to insert the functional layer to increase the growth rate. Therefore, there is a third effect of shortening the growth time.

FIG. 1 shows a structure of a conventional nitride semiconductor light emitting device.
2 is a view showing an active layer region of the multiple quantum well structure of FIG.
3 is a view showing a structure of a nitride-based light-emitting device in which a P-type dopant is diffused on an active layer according to the present invention.
4 illustrates a method of manufacturing the nitride semiconductor light emitting device of the present invention.
5 is a view showing an active layer structure of a multiple quantum well structure according to a first embodiment of the present invention.
6 is a view showing an active layer structure of a multiple quantum well structure according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the 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 size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

FIG. 3 is a view showing a structure of a nitride semiconductor light emitting device in which a P-type dopant is diffused on an active layer according to the present invention.

3, a buffer layer 120 is formed on an insulating substrate 100 on which protrusion patterns are formed, and an undoped semiconductor layer 121, an N-type semiconductor layer 122, An active layer 123, a P-type semiconductor layer 124, and a transparent metal layer 125 are stacked. The n-type semiconductor layer 122 and the p-type semiconductor layer 124 are exposed to the outside and each include an n-type electrode 127 and a p-type electrode 126. The active layer 123 and the p- Type dopant diffusion layer and the final quantum barrier layer in which the P-type dopant of the active layer is not diffused is formed between the first electrode layer and the second electrode layer.

The substrate 100 may have a protrusion pattern and may be formed of any one of sapphire (Al 2 O 3), SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP and Ge. The transparent electrode layer 116 may be formed of a transparent conductive material such as ITO, IZO, and ITZO.

The buffer layer 120, the undoped semiconductor layer 121, the N-type semiconductor layer 122, the active layer 123 and the P-type semiconductor layer 124 may be formed by chemical vapor deposition (CVD), molecular beam epitaxy (MBE) But may be formed on the substrate 100 by a method such as sputtering, vapor phase epitaxy (HVPE) or the like, but is not limited thereto.

4 illustrates a method of manufacturing the nitride semiconductor light emitting device of the present invention.

Referring to FIG. 4, a P-type dopant atmosphere is formed before the P-type semiconductor layer is grown. After the buffer layer 120, the nontype semiconductor layer 121, the N-type semiconductor layer 122 and the active layer 123 are sequentially grown on the substrate 100, the inside of the MOCVD reactor is converted into a P type dopant atmosphere, Type dopant atmosphere. At this time, the P-type dopant 150 is diffused into the last quantum barrier layer of the active layer 123, and then the P-type semiconductor layer is grown. The inside of the MOCVD reactor can form a P-type dopant atmosphere within 1 second to 10 minutes. Further, Mg may be preferably used as the P-type dopant. In order to grow the P-type semiconductor layer, a ramping time is required. In the case of the present invention, the process of the P-type dopant atmosphere can be inserted in the ramping time. Therefore, it is not necessary to insert the functional layer for increasing the hole injection efficiency into the active layer 123, and thus the growth time is shortened.

Embodiments of the present invention are diagrams illustrating active layer regions of the multiple quantum well structure of FIG.

5 is a view showing an active layer structure of a multiple quantum well structure according to a first embodiment of the present invention.

Referring to FIG. 5, the active layer 123 of the nitride semiconductor light emitting device according to the first embodiment of the present invention has a multi quantum well (MQW) structure as follows. A plurality of quantum barrier layers 123a and quantum well layers 123b between the quantum barrier layers 123a are formed between the N-type semiconductor layer 122 and the P- .

In addition, the hole inducing layer 200 interposed between the active layer 123 and the P-type semiconductor layer may include a P-type dopant diffusion layer 200b in which a P-type dopant is diffused and an energy level is relatively increased, and a P- And the last quantum barrier layer 200a of the active layer 123.

The N-type semiconductor layer 122 and the P-type semiconductor layer 124 may be formed of a compound III-nitride semiconductor layer such as (Al, In, Ga) N. For example, the N-type semiconductor layer 122 and the P-type semiconductor layer 124 may be N-type and P-type GaN, or N-type and P-type AlGaN, respectively.

The quantum barrier layers 123a may be formed by doping a p-type (p +) impurity or an n-type (n +) impurity into the GaN-based semiconductor material. The quantum well layers 123b may be made of InxGa1-xN (0 < x < 1) and silicon may be doped to lower the driving voltage.

In addition, the last quantum barrier layer 200a may be formed of a GaN-based or InGaN-based semiconductor layer as a single layer, and the P-type dopant diffusing layer 200b may be formed of a GaN-based semiconductor layer in an MOCVD reactor formed in a P- A P-type dopant is diffused into the gate electrode. When the P-type dopant is diffused, the operating voltage level of the P-type semiconductor layer 124, the P-type dopant diffused layer 200b and the last quantum barrier layer 200a ) Sequentially lower the operating voltage level. Therefore, the holes injected into the P-type semiconductor layer 124 can be easily transferred to the active layer 123 through the P-type dopant diffusion layer 200b and the last quantum barrier layer 200a. Further, the holes of the P-type semiconductor layer 124 can easily reach the active layer 123, so that the operating voltage of the nitride semiconductor light emitting device is lowered.

In addition, the nitride semiconductor light emitting device of the present invention has an effect of improving luminous efficiency and manufacturing yield by forming the hole inducing layer 200 between the active layer 123 and the P-type semiconductor layer 124.

FIG. 6 is a view showing a structure of an active layer 123 of a multiple quantum well structure according to a second embodiment of the present invention.

6, the active layer region of the nitride semiconductor light emitting device according to the second embodiment of the present invention includes an N-type semiconductor layer 122, an active layer 123, a hole inducing layer 300, and a P-type semiconductor layer 124, Lt; / RTI &gt;

The active layer 123 includes a plurality of quantum barrier layers 123a and quantum well layers 123b between the quantum barrier layers 123a.

The hole inducing layer 300 interposed between the active layer 123 and the P-type semiconductor layer 124 is formed on the first quantum barrier layer 300a, the second quantum barrier layer 300b, and the P Type dopant diffusion layer 300c.

The first quantum barrier layer 300a and the second quantum barrier layer 300b may be formed of a GaN-based or InGaN-based semiconductor layer. In addition, the first quantum barrier layer 300a and the second quantum barrier layer 300b may be formed of InGaN-based semiconductor layers and have different In compositions.

The holes injected from the P-type semiconductor layer 124 pass through the P-type dopant diffusion layer 300c, the second quantum barrier layer 300b and the first quantum barrier layer 300a to form the active layer 123 ). &Lt; / RTI &gt; This has the advantage that the coupling ratio of the holes and electrons of the active layer 123 is increased and the driving voltage of the light emitting device is lowered.

That is, in the nitride semiconductor light emitting device of the present invention, the hole inducing layer 300 is formed between the active layer 123 and the P-type semiconductor layer 124 to smoothly inject holes into the active layer 123, .

Therefore, in the nitride semiconductor light emitting device and the method of manufacturing the same according to the present invention, the P-type dopant is diffused in the last quantum barrier layer of the active layer, the energy level of the quantum barrier layer is relatively increased and holes are injected smoothly into the active layer Thereby improving the luminous efficiency.

Further, the electrical characteristics of the gallium nitride-based light-emitting diode device are improved by forming the P-type dopant atmosphere.

As a result of comparing the operating voltage of the conventional nitride semiconductor light emitting device and the present invention wherein Mg is diffused in the final quantum barrier layer of the active layer by holding for 10 seconds in a Mg atmosphere, the conventional light emitting device has an operating voltage of 2.99 V, The device was 2.94V, and the operating voltage (VF) was improved by 0.05V.

Further, it is possible to form a P-type dopant atmosphere in a ramping time for growing the P-type semiconductor layer after completion of growth of the active layer, and it is not necessary to insert the functional layer for increasing the hole injection efficiency into the active layer, There is an effect to shorten.

100: insulating substrate 120: buffer layer
121: Undoped layer 122: N-type semiconductor layer
123: active layer 200,300: hole-guiding layer
124: P-type semiconductor layer 125: transparent electrode layer
126: P-type electrode 127: N-type electrode

Claims (12)

Board;
A buffer layer and an undoped semiconductor layer formed on the substrate;
An N-type semiconductor layer and a P-type semiconductor layer formed on the undoped semiconductor layer;
An active layer of a multiple quantum well structure interposed between the N-type semiconductor layer and the P-type semiconductor layer and having a plurality of quantum well layers and a plurality of quantum barrier layers alternately arranged; And
And a hole inducing layer interposed between the active layer and the P-type semiconductor layer,
The hole inducing layer is composed of a quantum barrier layer closest to the P-type semiconductor layer among the quantum barrier layers of the active layer, and a P-type dopant diffusion layer disposed between the quantum barrier layer and the P-
Type semiconductor layer, the P-type semiconductor layer, the P-type dopant diffusion layer, and the quantum barrier layer closest to the P-type semiconductor layer are sequentially lowered. The nitride semiconductor light emitting device according to claim 1, wherein the P-type dopant is Mg. The nitride semiconductor light emitting device according to claim 1, wherein the quantum barrier layer is formed of a GaN-based or InGaN-based semiconductor layer. The nitride semiconductor light emitting device according to claim 1, wherein the quantum barrier layer closest to the P-type semiconductor layer comprises a first quantum barrier layer and a second quantum barrier layer. The nitride semiconductor light emitting device according to claim 4, wherein the first quantum barrier layer and the second quantum barrier layer are formed of a GaN-based or InGaN-based semiconductor layer. 5. The nitride semiconductor light emitting device according to claim 4, wherein the first quantum barrier layer and the second quantum barrier layer are formed of an InGaN-based semiconductor layer and have different In compositions. Forming a buffer layer, an undoped semiconductor layer, and an N-type semiconductor layer on a substrate;
Forming an active layer of a multiple quantum well structure in which a plurality of quantum well layers and a plurality of quantum barrier layers are alternately arranged on the N-type semiconductor layer;
After the formation of the active layer, before forming the P-type semiconductor layer, converting the interior of the MOCVD reactor into a P-type dopant atmosphere to expose the P-type dopant to the quantum barrier layer of the active layer closest to the P-
A P-type dopant is diffused in the quantum barrier layer closest to the P-type semiconductor layer among the quantum barrier layers of the active layer to form a hole induction layer consisting of a quantum barrier layer closest to the P-type semiconductor layer and a P-type dopant diffusion layer , &Lt; / RTI &
And forming a P-type semiconductor layer and a transparent electrode layer on the hole inducing layer. 8. The method according to claim 7, wherein the P-type dopant is Mg. 8. The method according to claim 7, wherein the quantum barrier layer closest to the P-type semiconductor layer is formed of a GaN-based or InGaN-based semiconductor layer. 8. The method of claim 7, wherein the quantum barrier layer closest to the P-type semiconductor layer comprises a first quantum barrier layer and a second quantum barrier layer. 11. The method according to claim 10, wherein the first quantum barrier layer and the second quantum barrier layer are formed of a GaN-based or InGaN-based semiconductor layer. 11. The method according to claim 10, wherein the first quantum barrier layer and the second quantum barrier layer are formed of InGaN-based semiconductor layers and have different In compositions.

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