KR20130094451A - 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 of the present invention and a method of manufacturing the same 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 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 positive covalentness layer interposed between the active layer and the P-type semiconductor layer, wherein the positive covalentness layer comprises a quantum barrier layer of the active layer and a P-type dopant diffusion layer diffused into the quantum barrier layer, and the P-type semiconductor. The energy levels of the 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 smoothly injects holes into the active layer through a positive covalent layer composed of a semiconductor layer used for the quantum well layer of the active layer or a semiconductor layer in which the P-type dopant is diffused between the active layer and the P-type semiconductor layer. It works.

Description

Nitride semiconductor light emitting device and method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device, and more particularly, to a nitride semiconductor light emitting device which diffuses a P-type dopant into the last barrier layer of an active layer to facilitate hole injection and improves luminous efficiency.

In general, nitrides of Group III elements such as gallium nitride (GaN) and aluminum nitride (AlN) used in nitride semiconductor light emitting devices have excellent thermal stability and have a direct transition type energy band structure. It is attracting much attention as a material for optoelectronic devices 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.

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

1 and 2, in the conventional nitride semiconductor light emitting device, a buffer layer 20 is formed on an insulating substrate 10, and an undoped semiconductor layer 21 and an N-type semiconductor layer are formed on the buffer layer 20. (22), the active layer 23, the P-type semiconductor layer 24, and the transparent metal layer 25 are laminated. The N-type electrode 27 and the P-type electrode 26 are formed on the N-type semiconductor layer 22 and the P-type semiconductor layer 24 exposed to the outside, respectively.

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, and in addition to sapphire, zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (silicon carbide) SiC), aluminum nitride (AlN), or the like.

The active layer 23 is a region in which electrons and holes are recombined, and a plurality of quantum barrier layers 23a and quantum well layers 23b, which are represented by a general formula of InxGa1-xN (0 ≦ x ≦ 1), are alternately formed. It has a quantum well structure. The emission wavelength emitted from the nitride semiconductor light emitting device is determined according to the type of material constituting 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 μs. Among them, as shown in FIG. 2, the active layer 23 of the multi-quantum well structure has better light efficiency than the single quantum well structure and has a high luminous output.

The light efficiency of the nitride semiconductor light emitting device is basically determined by the probability of recombination of electrons and holes in the active layer, that is, internal quantum efficiency. In order to improve the internal quantum efficiency, research has been conducted mainly to improve the structure of the active layer itself or to increase the effective mass of the carrier.

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

As such, when 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, thereby deteriorating the luminous efficiency.

Recently, a method of additionally forming a nano laminated structure has been proposed to improve hole injection characteristics in an active layer. However, a long growth time for forming a nano laminated structure causes a problem in that the overall productivity decreases.

In addition, an AlGaN-based electron barrier layer forming method has been proposed for electron overflow and hole injection, but aluminum (Al) acts as a source of contamination during semiconductor layer growth, thereby degrading device characteristics. In addition, an additional process is required to keep the reactor in a high temperature state for a long time to form the electronic barrier layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a nitride semiconductor light emitting device having a light emission efficiency and an operating voltage by diffusing a P-type dopant in the last barrier layer of the active layer and a method of manufacturing the same.

Another object of the present invention is to provide a nitride semiconductor light emitting device and a method of manufacturing the same, which improve electrical properties of the device by forming a P-type dopant atmosphere for improving hole injection efficiency into the active layer.

In addition, the present invention is a nitride semiconductor that can shorten the process time by eliminating the insertion process of the functional layer for increasing the hole injection efficiency into the active layer by diffusing the P-type dopant in the last barrier layer (barrier) of the active layer Another object is to provide a light emitting device and a method of manufacturing the same.

The nitride semiconductor light emitting device of the present invention for solving the above problems of the prior art, the 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 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 positive covalentness layer interposed between the active layer and the P-type semiconductor layer, wherein the positive covalentness layer comprises a quantum barrier layer of the active layer and a P-type dopant diffusion layer diffused into the quantum barrier layer, and the P-type semiconductor. The energy levels of the layer, the P-type dopant diffusion layer and the quantum barrier layer are sequentially lowered.

In addition, the method of manufacturing a nitride semiconductor light emitting device of the present invention comprises the steps of forming a buffer layer, an undoped semiconductor layer, an N-type semiconductor layer on the substrate, a plurality of quantum well layer and a plurality of quantum barrier on the N-type semiconductor layer Forming an active layer having a multi-quantum well structure in which layers are alternately disposed, and after forming the active layer and converting an inside of a MOCVD reactor into a P-type dopant atmosphere before forming a P-type semiconductor layer, the active layer adjacent to the P-type semiconductor layer Exposing a P-type dopant to a quantum barrier layer of the P-type dopant, forming a P-type dopant on the quantum barrier layer of the active layer to form a positive co-conducting layer including the quantum barrier layer and the P-type dopant diffusion layer, and Forming a P-type semiconductor layer, a transparent electrode layer on the induction layer.

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 barrier layer (Barrier) of the active layer to increase the energy level of the barrier layer relatively, so that holes can be smoothly injected into the active layer There is a first effect of improving luminous efficiency.

In addition, 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 hole injection efficiency into the active layer. .

In addition, 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 within a ramping time for growing the P-type semiconductor layer after the growth of the active layer is completed, and thus the hole injection efficiency into the active layer There is a third effect of shortening the growth time since the insertion of the functional layer for the increase of is not necessary.

1 illustrates a structure of a conventional nitride semiconductor light emitting device.
FIG. 2 is a diagram illustrating an active layer region of the multi-quantum well structure of FIG. 1.
3 is a diagram illustrating 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 diagram illustrating an active layer structure of a multi-quantum well structure according to a first embodiment of the present invention.
6 is a view showing an active layer structure of a multi-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 numbers refer to like elements throughout.

3 is a diagram illustrating 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.

Referring to FIG. 3, in the present invention, a buffer layer 120 is formed on an insulating substrate 100 having protrusion patterns formed thereon, and an undoped semiconductor layer 121 and an N-type semiconductor layer 122 are formed on the buffer layer 120. The active layer 123, the P-type semiconductor layer 124, and the transparent metal layer 125 are stacked. In addition, the N-type semiconductor layer 122 and the P-type semiconductor layer 124 exposed to the outside includes an N-type electrode 127 and a P-type electrode 126, respectively, the active layer 123 and the P-type semiconductor layer A positively-coated layer 200 is formed between 124 between the P-type dopant diffusion layer and the last quantum barrier layer in which the P-type dopant of the active layer is not diffused.

The substrate 100 may have a protrusion pattern, and may use 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), It may be formed on the substrate 100 by a method such as sputtering, hydroxide vapor phase epitaxy (HVPE), 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 growth of the P-type semiconductor layer. After the buffer layer 120, the undoped semiconductor layer 121, the N-type semiconductor layer 122, and the active layer 123 are grown in this order on the substrate 100, the inside of the MOCVD reactor is converted into a P-type dopant atmosphere for a predetermined time. Maintain a mold dopant atmosphere. At this time, the P-type dopant 150 diffuses into the last quantum barrier layer of the active layer 123, and then the P-type semiconductor layer is grown. Inside the MOCVD reactor can form a P-type dopant atmosphere within 1 second to 10 minutes. Also, preferably, P-type dopant may be Mg. In order to grow a P-type semiconductor layer, a ramping time is required. In the present invention, a process of a P-type dopant atmosphere may be inserted within a ramping time. Therefore, since the insertion of the functional layer for increasing the hole injection efficiency into the active layer 123 is unnecessary, there is a shortening the growth time.

Embodiments of the present invention below show the active layer region of the multi-quantum well structure of FIG.

5 is a diagram illustrating an active layer structure of a multi-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 is formed in a multi quantum well (MQW) structure as follows. An active layer 123 composed of a plurality of quantum barrier layers 123a and quantum well layers 123b between the quantum barrier layers 123a is formed between the N-type semiconductor layer 122 and the P-type semiconductor layer 124. Is formed.

In addition, in the positive sharing layer 200 interposed between the active layer 123 and the P-type semiconductor layer, the P-type dopant diffusion layer 200b and the P-type dopant, in which the P-type dopant is diffused and the energy level is relatively increased, are not diffused. The last quantum barrier layer 200a of the active layer 123 is formed.

The N-type semiconductor layer 122 and the P-type semiconductor layer 124 may be formed of a compound-based group 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.

In addition, the quantum barrier layers 123a may be formed by doping p-type (p +) impurities or n-type (n +) impurities to a GaN-based semiconductor material. The quantum well layers 123b may be formed of In x Ga 1-x N (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 diffusion layer 200b may be a GaN-based semiconductor layer in a MOCVD reactor formed of a P-type dopant atmosphere. P-type dopant is formed by diffusion. When the P-type dopant is diffused, the operating voltage level is higher than that of the GaN-based semiconductor layer. As shown in the drawing, the P-type semiconductor layer 124, the P-type dopant diffusion layer 200b, and the last quantum barrier layer 200a of the active layer are shown. ), The operating voltage levels are sequentially lowered. Accordingly, holes injected into the P-type semiconductor layer 124 may be easily transferred to the active layer 123 through the P-type dopant diffusion layer 200b and the last quantum barrier layer 200a. In addition, holes in the P-type semiconductor layer 124 can easily reach the active layer 123, thereby lowering the operating voltage of the nitride semiconductor light emitting device.

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

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

Referring to FIG. 6, the active layer region of the nitride semiconductor light emitting device according to the second exemplary embodiment of the present invention may be an N-type semiconductor layer 122, an active layer 123, a positive-coating layer 300, and a P-type semiconductor layer 124. Is done.

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

The positive sharing layer 300 interposed between the active layer 123 and the P-type semiconductor layer 124 may include the last first quantum barrier layer 300a, the second quantum barrier layer 300b, and P of the active layer 123. The dopant diffusion layer 300c is formed.

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 an InGaN-based semiconductor layer, but may have different In compositions.

The hole sharing layer 300 has holes injected from the P-type semiconductor layer 124 through the P-type dopant diffusion layer 300c, the second quantum barrier layer 300b, and the first quantum barrier layer 300a. You can easily move to). As a result, the bonding ratio between the holes and the electrons of the active layer 123 is increased, and the driving voltage of the light emitting device is lowered.

That is, the nitride semiconductor light emitting device of the present invention forms a positive covalent layer 300 between the active layer 123 and the P-type semiconductor layer 124 to facilitate the hole injection to the active layer 123, luminous efficiency and manufacturing yield It has the effect of improving.

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 into the last quantum barrier layer of the active layer so that the energy level of the quantum barrier layer is relatively increased, and holes are smoothly injected into the active layer. The luminous efficiency is improved by making it possible.

In addition, the electrical characteristics of the gallium nitride based light emitting diode device may be improved by forming a P-type dopant atmosphere.

As a result of comparing the operating voltage of the conventional nitride semiconductor light emitting device with the Mg diffused in the last quantum barrier layer of the active layer by holding it for 10 seconds in the Mg atmosphere, the conventional light emitting device has an operating voltage of 2.99V, The device has an improved operating voltage (VF) of 0.05V to 2.94V.

In addition, since the P-type dopant atmosphere can be formed within a ramping time for growing the P-type semiconductor layer after the growth of the active layer is completed, the growth time is not required since the insertion of the functional layer is not required to increase the hole injection efficiency into the active layer. It is effective to shorten.

100: insulating substrate 120: buffer layer
121: undoped layer 122: N-type semiconductor layer
123: active layer 200, 300: positive sharing 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 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
It includes a positive covalent layer interposed between the active layer and the P-type semiconductor layer,
The positive coherence layer is made of a quantum barrier layer of the active layer and a P-type dopant diffusion layer diffused in the quantum barrier layer,
And the energy levels of the P-type semiconductor layer, the P-type dopant diffusion layer, and the quantum barrier layer are sequentially lowered. The nitride semiconductor light emitting device of claim 1, wherein the P-type dopant is Mg. The nitride semiconductor light emitting device of claim 1, wherein the quantum barrier layer is formed of a GaN-based or InGaN-based semiconductor layer. The nitride semiconductor light emitting device of claim 1, wherein the quantum barrier layer comprises a first quantum barrier layer and a second quantum barrier layer. The nitride semiconductor light emitting device of 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. The nitride semiconductor light emitting device of claim 4, wherein the first quantum barrier layer and the second quantum barrier layer are formed of an InGaN-based semiconductor layer, but have different In compositions. Forming a buffer layer, an undoped semiconductor layer, an N-type semiconductor layer on the substrate,
Forming an active layer of a multi-quantum well structure in which a plurality of quantum well layers and a plurality of quantum barrier layers are alternately disposed on the N-type semiconductor layer;
After forming the active layer and before forming the P-type semiconductor layer, converting the inside 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 adjacent to the P-type semiconductor layer;
P-type dopant is diffused into the quantum barrier layer of the active layer, to form a positive co-conducting layer consisting of the quantum barrier layer and the P-type dopant diffusion layer,
And forming a P-type semiconductor layer and a transparent electrode layer on the positive sharing layer. The method of claim 7, wherein the P-type dopant is Mg. The method of claim 7, wherein the quantum barrier layer is formed of a GaN-based or InGaN-based semiconductor layer. 8. The method of claim 7, wherein the quantum barrier layer comprises a first quantum barrier layer and a second quantum barrier layer. The method of 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. The method of claim 10, wherein the first quantum barrier layer and the second quantum barrier layer are formed of an InGaN-based semiconductor layer, wherein the In composition is different from each other.

Images