KR20120011198A - Light emitting device, light emitting device package and method for fabricating light emitting device - Google Patents

Abstract

PURPOSE: A light emitting device, a light emitting device package, and a method for manufacturing a light emitting device are provided to improve the light efficiency of a light emitting device by increasing the number of electronics and holes which are recombined in an active layer. CONSTITUTION: An n-type semiconductor layer is formed on a substrate. An active layer is formed on the n-type semiconductor layer. The active layer includes one or more well layers and barrier layers. An electron blocking layer consisting of InAlN(Indium Aluminium Nitride) is formed on the active layer. A p-type semiconductor layer is formed on the electron blocking layer.

Description

Light emitting device, light emitting device package and method for manufacturing light emitting device {Light emitting device, light emitting device package and method for fabricating light emitting device}

The embodiment relates to a light emitting device, an light emitting device package, and a method of manufacturing the light emitting device in which the electron blocking layer (EBL) is formed.

Light-emitting devices such as light-emitting diodes (LEDs) and laser diodes (LDs) using semiconductors of Group 3-5 or 2-6 compound semiconductor materials of semiconductors have been developed through the development of thin film growth technology and device materials. Various colors such as green, blue, and ultraviolet light can be realized, and efficient white light can be realized by using fluorescent materials or combining colors, and low power consumption, semi-permanent life, and quicker than conventional light sources such as fluorescent and incandescent lamps can be realized. It has the advantages of response speed, safety and environmental friendliness.

Therefore, a white light emitting device that can replace a fluorescent light bulb or an incandescent bulb that replaces a Cold Cathode Fluorescence Lamp (CCFL) constituting a backlight of a transmission module of an optical communication means and a liquid crystal display (LCD) display device. Applications are expanding to diode lighting devices, automotive headlights and traffic lights.

The conventional semiconductor light emitting device includes a sapphire substrate and an n-type semiconductor layer, an active layer and a p-type semiconductor layer sequentially formed thereon. The light emitting element also includes an n-type electrode and a p-type electrode connected to the n-type semiconductor layer and the p-type semiconductor layer, respectively. The active layer may have a multi-quantum well (MQW) structure in which a quantum barrier layer of GaN and a quantum well layer of InGaN are alternately stacked several times.

When a predetermined current is applied to each electrode, electrons provided from the n-type semiconductor layer and holes provided from the p-type semiconductor layer are recombined in the active layer of the multi-quantum well structure to emit short wavelength light corresponding to green or blue color. .

Here, an electron blocking layer (EBL) made of a nitride semiconductor having a larger energy band gap than the p-type semiconductor layer is formed between the active layer and the p-type semiconductor layer.

Embodiments provide a light emitting device, a light emitting device package, and a method of manufacturing the light emitting device having an electron blocking layer having low valence band offset (ΔEv) while forming lattice matching with an active layer.

The light emitting device of the embodiment includes a substrate; An n-type semiconductor layer on the substrate; An active layer on the n-type semiconductor layer; An electron blocking layer disposed on the active layer and formed of InAlN; And a p-type semiconductor layer on the electron blocking layer. .

In addition, the composition of the InAlN material, when expressed as In _x Al _{1 - x} N, x is 0.15 to 0.20. Preferably, x is 0.17 to 0.18.

In addition, the active layer includes at least one well layer and a barrier layer, and the active layer in contact with the electron blocking layer is made of GaN.

In addition, the p-type semiconductor layer is made of GaN.

In addition, the thickness of the electron blocking layer is 10 to 50 nm.

In addition, the electron blocking layer includes a p-type dopant.

The light emitting device package of the embodiment includes a package body; A light emitting device provided on the package body; First and second electrode layers provided on the package body and respectively connected to the light emitting devices; And a filler surrounding the light emitting device. The light emitting device includes a substrate; An n-type semiconductor layer on the substrate; An active layer on the n-type semiconductor layer; An electron blocking layer disposed on the active layer and formed of InAlN; And a p-type semiconductor layer on the electron blocking layer. .

A method of manufacturing a light emitting device of an embodiment includes forming an n-type semiconductor layer on a substrate; Forming an active layer on the n-type semiconductor layer; Forming an electron blocking layer of InAlN on the active layer; And forming a p-type semiconductor layer formed on the electron blocking layer. It includes.

According to the embodiment, it is possible to provide a light emitting device, a light emitting device package, and a method of manufacturing the light emitting device having an electron blocking layer having a low valence band offset? Ev while lattice matching with an active layer.

1 is an energy band diagram of a semiconductor light emitting device having an electron blocking layer.
2 is a cross-sectional view of a semiconductor light emitting device according to an embodiment.
3 is an energy band diagram of a semiconductor light emitting device having an electron blocking layer formed of InAlN according to an embodiment.
4 is a cross-sectional view illustrating a structure of a semiconductor light emitting device according to another embodiment.
5 is a cross-sectional view of a light emitting device package according to an embodiment.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

In the description of the above embodiments, each layer (region), region, pattern or structures may be "on" or "under" the substrate, each layer (layer), region, pad or pattern. In the case of what is described as being formed, "on" and "under" include both being formed "directly" or "indirectly" through another layer. In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

Example  One

1 is an energy band diagram of a semiconductor light emitting device having a general electron blocking layer.

As shown, the electron blocking layer (EBL) has a larger energy bandgap than the p-type semiconductor layer, so that electrons provided from the n-type semiconductor layer do not recombine in the active layer of the MQW structure and are overwritten to the p-type semiconductor layer. It can effectively prevent the flow. Therefore, the electron blocking layer may improve light efficiency of the light emitting device by reducing electrons consumed due to overflowing.

In order to achieve the electron blocking effect, the electron blocking layer must have a large energy band gap and an appropriate thickness. As the electron blocking layer, a p-type AlGaN or InAlGaN layer is mainly used.

In the case of the AlGaN layer, since the lattice constant is different from that of the GaN layer, which is the last barrier layer of the active layer, the lattice constant may not be matched with GaN during growth, and thus, a high quality electron blocking layer may be difficult to obtain.

Accordingly, instead of the AlGaN layer, an InAlGaN layer may be used in which the GaN and the lattice constant may be grown in the same layer while having an energy band gap larger than that of GaN.

However, in the case of the conventional electron blocking layer such as the AlGaN layer and the InAlGaN layer, the ratio of the conduction band offset (ΔEc) and the valence band offset (ΔEv) is about 7: 3. Accordingly, the electron band can be prevented from leaking from the active layer to the p-type semiconductor layer by the conduction band offset ΔEc, but at the same time the value of the valence band offset ΔEv increases, so that holes are injected into the active layer from the p-type semiconductor layer. It will also block. Reducing the inflow of holes, which are relatively insufficient in the active layer, compared to the electrons, lowers the luminous efficiency of the light emitting device.

Accordingly, there is a need to provide an electron blocking layer having a valence band offset? Ev which is relatively lower than the conduction band offset? Ec while lattice matching with the active layer in the semiconductor light emitting device.

2 is a cross-sectional view of the semiconductor light emitting device according to the first embodiment, illustrating a semiconductor light emitting device having a horizontal structure. Hereinafter, an embodiment of a semiconductor light emitting device of the present invention will be described with reference to FIG. 2.

As shown in FIG. 2, the semiconductor light emitting device includes a substrate 110, an n-type semiconductor layer 120, an active layer 130, an electron blocking layer 140, and p sequentially formed on the substrate 110. A type semiconductor layer 150.

The substrate 110 may be formed of a light transmitting material, for example, sapphire (Al ₂ O ₃ ), GaN, SiC, ZnO, Si, GaP, InP, Ga ₂ O ₃ , GaAs, or the like.

The n-type semiconductor layer 120 is formed on the substrate 110. The n-type semiconductor layer 120 may further include an undoped semiconductor layer under the n-type semiconductor layer 120, but is not limited thereto. The undoped semiconductor layer is a layer formed to improve the crystallinity of the n-type semiconductor layer 120, except that the n-type dopant is not doped and thus has a significantly lower electrical conductivity than the n-type semiconductor layer 120, It may be the same as the n-type semiconductor layer 120.

n-type semiconductor material having a semiconductor layer 120 is _{In x Al y Ga 1 -x- y} N formula (wherein Im 0≤x≤1, 0≤y≤1, 0≤x + y≤1) of, For example, it may be selected from GaN, AlN, AlGaN, InGaN, InN, InAlGaN, and the like, and n-type dopants such as Si, Ge, Sn, Se, Te, and the like may be doped. For example, the n-type semiconductor layer 120 may be formed of a GaN layer doped with an n-type dopant.

The active layer 130 is formed on the n-type semiconductor layer 120. The active layer 130 is, for example, semiconductor material having the _{In x Al y Ga 1 -x- y} N formula (wherein Im 0≤x≤1, 0≤y≤1, 0≤x + y≤1) of It may include, and may include at least one of a quantum wire structure, a quantum dot structure, a single quantum well structure, or a multi quantum well structure (MQW). For example, the active layer 230 may be formed of an InGaN / GaN layer having an MQW structure.

The active layer 130 generates light by energy generated during recombination of electrons and holes provided from the n-type semiconductor layer 120 and the p-type semiconductor layer 150.

An electron blocking layer (EBL) 140 formed of a semiconductor having a larger energy band gap than the p-type semiconductor layer 150 is formed on the active layer 130. In an embodiment, the electron blocking layer 140 is made of InAlN.

The p-type semiconductor layer 150 is formed on the electron blocking layer 140. p-type semiconductor material having a semiconductor layer 150 is _{In x Al y Ga 1 -x- y} N formula (wherein Im 0≤x≤1, 0≤y≤1, 0≤x + y≤1) of, For example, it may be selected from GaN, AlN, AlGaN, InGaN, InN, InAlGaN, and the like, and p-type dopants such as Mg, Zn, Ca, Sr, and Ba may be doped. For example, the p-type semiconductor layer 150 may be formed of a GaN layer doped with a p-type dopant.

The p-type electrode 160 is formed on the p-type semiconductor layer 150. Meanwhile, portions of the p-type semiconductor layer 150, the electron blocking layer 140, and the active layer 130 are removed by etching, thereby exposing a portion of the n-type semiconductor layer 120 on the bottom surface thereof. The n-type electrode 170 is formed on the n-type semiconductor layer 120 exposed by etching, that is, the n-type semiconductor layer 120 where the active layer 130 is not formed.

Hereinafter, a semiconductor light emitting device according to an embodiment will be described in detail with reference to FIG. 3. 3 is an energy band diagram of a semiconductor light emitting device having an electron blocking layer formed of InAlN according to an embodiment.

The light emitting element of the embodiment has an electron blocking layer (EBL) made of InAlN.

In the field of light emitting devices, gallium nitride compound semiconductors (Gallium Nitride: GaN) have high thermal stability and wide energy bandgap (0.8 to 6.2 eV), which has attracted much attention in the development of high-power electronic components including LEDs. . One reason for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers that emit green, blue and white light. For example, GaN can be used to create white LEDs that can replace incandescent and blue LEDs that are beneficial for optical recording.

For this reason, the conventional n-type and p-type semiconductor layers are mainly made of GaN, and the active layer inserted between the n-type semiconductor layer and the p-type semiconductor layer is also mainly an InGaN / GaN layer having a multi-quantum well (MQW) structure. Is done. In addition, a p-type AlGaN or InAlGaN layer is mainly used as an electron blocking layer to prevent electrons from overflowing into the p-type semiconductor layer in the active layer. As such, GaN is generally included in the n-type semiconductor layer, the active layer, the electron blocking layer, and the p-type semiconductor layer. Since the n-type semiconductor layer and the p-type semiconductor layer are made of GaN, the active layer and the electron blocking layer inserted therebetween are also lattice matched with the n-type semiconductor layer and the p-type semiconductor layer during the growth process.

As such, the conventional electron blocking layer basically includes "GaN (gallium nitride)". However, the electron blocking layer of the embodiment does not contain Ga (gallium) contained in the n-type semiconductor layer, the p-type semiconductor layer, and the active layer, but has an electron blocking layer (EBL) made of InAlN. The suitability of InAlN as an electron barrier layer was confirmed by experiments and energy band diagrams.

Here, the composition formula of the InAlN is In _x Al _{1 - x} N can be expressed by (where, 0≤x≤1), e.g., when x is 0.17, and it had a composition formula of In _{0 .17} Al _{0 .83} N do. In the formula of In _x Al _{1 - x} N, when x is 0.15 to 0.20, it can be seen that InAlN approximates the lattice constant with GaN, which is a material of the active layer. In particular, when x is from 0.17 to 0.18, the lattice constant coincides with GaN, which is a material of the active layer. Accordingly, the electron blocking layer made of InAlN is lattice matched with GaN, which is a material of the active layer, to obtain a high quality electron blocking layer without deformation.

As shown in FIG. 3, the electron blocking layer made of InAlN according to the embodiment has a conduction band offset (ΔEc) of 1 eV and a valence band offset (ΔEv) of 0.2 eV. . That is, the ratio of the conduction band offset ΔEc and the valence band offset ΔEv is about 5: 1.

The electron blocking layer of the embodiment has a larger energy bandgap than the p-type semiconductor layer, similar to the electron blocking layer of the conventional p-type AlGaN, so that electrons provided from the n-type semiconductor layer are not recombined in the active layer of the MQW structure. The overflow to the type semiconductor layer is effectively prevented. Therefore, the electron blocking layer may reduce electrons consumed due to overflowing, thereby improving light efficiency of the light emitting device.

In addition, the electron blocking layer of the embodiment has a relatively low valence band offset (Ev) of 0.2 eV, so that holes of the p-type semiconductor layer can be easily injected into the active layer. Therefore, the light efficiency of the light emitting device may be improved by increasing the number of electrons and holes recombined in the active layer.

The electron blocking layer made of InAlN can be grown using MOCVD (Metal Organic Chemical Vapor Deposition), Molecular-Beam Epitaxy (MBE), or the like. The growth temperature of InAlN is usually from 780 to 880 ° C., and is grown at a low growth rate of 0.5 μm / h at a very high V / III ratio under low pressure of 200 torr or less. It is preferable that the thickness of the electron blocking layer which consists of such InAlN is 10-50 nm. InAlN does not have to be doped with a dopant, but may preferably be doped with a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The degree of InAlN doping can be appropriately adjusted as necessary.

As described above, in the embodiment, as the electron blocking layer 140, InAlN is used instead of AlGaN or InAlGaN, so that the lattice match with GaN is high and the conduction band offset ΔEc is high. As a low electron blocking layer can be implemented, the characteristics of the device can be improved by further improving the light efficiency of the light emitting device.

Example  2

Hereinafter, a semiconductor light emitting device according to another exemplary embodiment will be described in detail with reference to FIG. 4. 4 is a cross-sectional view illustrating a structure of a semiconductor light emitting device according to another embodiment, and illustrates a semiconductor light emitting device having a vertical structure.

As shown, the structural support layer 210 is formed at the bottom of the semiconductor light emitting device. The structure support layer 210 serves as a support layer and an electrode of the light emitting device, and may be formed of a silicon (Si) substrate, a GaAs substrate, a Ge substrate, or a metal layer.

The p-type electrode 260 is formed on the structure support layer 210, and it is preferable that the p-type electrode 260 is made of a metal having high reflectance to simultaneously serve as an electrode and a reflective role.

The p-type semiconductor layer 250, the electron blocking layer 240, the active layer 230, and the n-type semiconductor layer 220 are sequentially formed on the p-type electrode 260, and n is formed on the n-type semiconductor layer 220. The type electrode 270 is formed.

Among these, the p-type semiconductor layer 250 may be made of a GaN layer doped with p-type conductive impurities, as described above, and the active layer 230 may be made of an InGaN / GaN layer having an MQW structure. The type semiconductor layer 220 may be formed of a GaN layer doped with n-type conductive impurities.

The electron blocking layer 240 is made of InAlN. The composition formula of InAlN is preferably In _x Al _1-x N (where 0 ≦ _x ≦ 1), wherein x is 0.15 to 0.20, in particular x is 0.17 to 0.18. In this case, the electron blocking layer made of InAlN may be lattice matched with GaN, which is a material of the active layer, to obtain a high quality electron blocking layer without deformation.

In addition, as shown in FIG. 3, the electron blocking layer 240 has a high conduction band offset ΔEc while a low valence band offset ΔEv, so that electrons provided from the n-type semiconductor layer may be holed in the active layer. It can effectively prevent overflow with the p-type semiconductor layer without recombination with it, and also allows the holes of the p-type semiconductor layer to be easily injected into the active layer. Therefore, the electron blocking layer 240 according to the second embodiment may also obtain the same effects and effects as the first embodiment.

5 is a cross-sectional view of an embodiment of a light emitting device package. Hereinafter, an embodiment of the light emitting device package will be described with reference to FIG. 5.

As shown, the light emitting device package according to the embodiment is installed in the package body 10, the first electrode layer 21 and the second electrode layer 22 formed on the package body 10, the package body 10 The light emitting device 100 according to the embodiment is electrically connected to the first electrode layer 21 and the second electrode layer 22, and the filler 30 surrounding the light emitting device 100 is included.

The package body 10 may be formed of a silicon material, a synthetic resin material, or a metal material. An inclined surface may be formed around the light emitting device 100 to increase light extraction efficiency.

The first electrode layer 21 and the second electrode layer 22 are electrically separated from each other, and provide power to the light emitting device 100. In addition, the first electrode layer 21 and the second electrode layer 22 may increase light efficiency by reflecting the light generated from the light emitting device 100, and discharge heat generated from the light emitting device 100 to the outside. It can also play a role.

The light emitting device 100 is installed on the package body 10 or on the first electrode layer 21 or the second electrode layer 22.

The light emitting device 100 may be electrically connected to the first electrode layer 21 and the second electrode layer 22 by any one of a wire method, a flip chip method, or a die bonding method.

The filler 30 surrounds and protects the light emitting device 100. In addition, the filler 30 may include a phosphor to change the wavelength of light emitted from the light emitting device 100.

The light emitting device package may include at least one or a plurality of light emitting devices of the above-described embodiments, but is not limited thereto.

A plurality of light emitting device packages according to the embodiment may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, or the like, which is an optical member, may be disposed on an optical path of the light emitting device package. The light emitting device package, the substrate, and the optical member may function as a light unit. Another embodiment may be implemented as a display device, an indicator device, or a lighting system including the semiconductor light emitting device or the light emitting device package described in the above embodiments, and for example, the lighting system may include a lamp or a street lamp. .

Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

In addition, the above description has been made with reference to the embodiment, which is merely an example, and is not intended to limit the present invention. Those skilled in the art to which the present invention pertains will be illustrated as above without departing from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

10: package body
21: first electrode layer
22: second electrode layer
30: filling material
100: light emitting element
110: substrate
120: n-type semiconductor layer
130: active layer
140: electronic blocking layer
150: p-type semiconductor layer
160: p-type electrode
170: n-type electrode

Claims (13)

Board;
An n-type semiconductor layer on the substrate;
An active layer on the n-type semiconductor layer;
An electron blocking layer disposed on the active layer and formed of InAlN; And
A p-type semiconductor layer on the electron blocking layer;
Light emitting device comprising a. The method of claim 1,
The composition of the InAlN material, when represented by In _x Al _{1 - x} N, x is 0.15 to 0.20 light emitting device. In the second,
X is 0.17 to 0.18. 4. The method according to any one of claims 1 to 3,
The active layer comprises at least one well layer and a barrier layer,
The active layer in contact with the electron blocking layer is made of GaN. According to claim 4,
The p-type semiconductor layer is a light emitting device made of GaN. 4. The method according to any one of claims 1 to 3,
The electron blocking layer has a thickness of 10 to 50 nm. 4. The method according to any one of claims 1 to 3,
The electron blocking layer includes a p-type dopant. Package body;
A light emitting device provided on the package body;
First and second electrode layers provided on the package body and respectively connected to the light emitting devices; And
A filler surrounding the light emitting device;
Including,
The light emitting device,
Board; An n-type semiconductor layer on the substrate; An active layer on the n-type semiconductor layer; An electron blocking layer disposed on the active layer and formed of InAlN; And a p-type semiconductor layer on the electron blocking layer. Light emitting device package comprising a. The method of claim 8,
The composition of the InAlN material, when represented by In _x Al _{1 - x} N, x is 0.15 to 0.20 light emitting device package. The method according to claim 9,
Wherein x is 0.17 to 0.18. The method according to any one of claims 8 to 10,
The active layer comprises at least one active layer and a barrier layer,
The active layer in contact with the electron blocking layer is a light emitting device package made of GaN. Forming an n-type semiconductor layer on the substrate;
Forming an active layer on the n-type semiconductor layer;
Forming an electron blocking layer of InAlN on the active layer; And
Forming a p-type semiconductor layer on the electron blocking layer;
Method of manufacturing a light emitting device comprising a. The method of claim 12,
The composition of the InAlN material, when represented by In _x Al _{1 - x} N, x is 0.15 to 0.20 manufacturing method of the light emitting device.

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