KR20100038339A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE: A semiconductor light emitting device is provided to improve the degradation of intensity of light due to refractive difference between the air and a resin material using a nitride layer. CONSTITUTION: An electrode(170) is electrically connected to a first conductive semiconductor layer(110,120). A second conductive semiconductor layer(140) is arranged under the first conductivity semiconductor layer. An active layer(130) is arranged between the first conductive semiconductor layer and the second conductive semiconductor layer. A reflective electrode layer(150) is arranged under the second conductive semiconductor layer. The first conductive semiconductor layer includes a nitride layer with a low refractive index and the nitride layer with a high refractive index. The nitride layer with the high refractive index is closer to an active layer than the refractive layer with the low refractive index.

Description

Semiconductor Light Emitting Device {SEMICONDUCTOR LIGHT EMITTING DEVICE}

The embodiment relates to a semiconductor light emitting device.

Group III-V nitride semiconductors are spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their physical and chemical properties. The III-V nitride semiconductor is usually made of a semiconductor material having a composition formula of In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).

A light emitting diode (LED) is a kind of semiconductor device that transmits and receives a signal by converting electricity into infrared light or light using characteristics of a compound semiconductor.

 It is widely used in the light emitting device for obtaining the light of the LED or LD using such a nitride semiconductor material, and is applied as a light source of various products such as keypad light emitting part of a mobile phone, an electronic board, a lighting device.

The embodiment provides a semiconductor light emitting device capable of improving light emission efficiency by disposing a nitride having a low refractive index on a surface of a vertical semiconductor light emitting device.

The embodiment provides a semiconductor light emitting device capable of improving light extraction efficiency by forming a nitride layer having a low refractive index on a nitride layer having a high refractive index in a vertical semiconductor light emitting device.

A semiconductor light emitting device according to an embodiment may include a first conductive semiconductor layer including a first nitride layer having a low refractive index and a second nitride layer having a high refractive index; An active layer formed on the first conductive semiconductor layer; A second conductive semiconductor layer formed on the active layer; It includes a reflective electrode layer formed on the second conductive semiconductor layer.

In another embodiment, a method of manufacturing a semiconductor light emitting device includes: forming a first nitride layer including aluminum on a substrate and forming a second nitride layer on the first nitride layer; Forming an active layer on the second nitride layer; Forming a second conductive semiconductor layer on the active layer; Forming a reflective electrode layer on the second conductive semiconductor layer; Forming a conductive support member on the reflective electrode layer; After removing the substrate, forming a first electrode on the surface of the first nitride layer.

The embodiment can improve light extraction efficiency.

According to the embodiment, a nitride layer having a relatively low refractive index may be disposed on the surface, and thus the brightness decrease due to a difference in refractive index with air or a resin may be improved.

1 is a side sectional view showing a semiconductor light emitting device according to the first embodiment;
2 to 5 illustrate a process of manufacturing a semiconductor light emitting device according to the embodiment;
6 and 7 illustrate an example in which roughness is formed on a surface of a semiconductor light emitting device according to an embodiment;

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. In the description of this embodiment, the definition of the top or bottom of each layer will be described based on the respective drawings.

1 is a cross-sectional view illustrating a semiconductor light emitting device according to an embodiment.

Referring to FIG. 1, the semiconductor light emitting device 100 may include first conductive semiconductor layers 110 and 120, an active layer 130, a second conductive semiconductor layer 140, a reflective electrode layer 150, and conductive layers having different refractive index layers. The support member 160 and the first electrode 170 are included.

The first conductive semiconductor layers 110 and 120 may be implemented as n-type semiconductor layers, and n-type dopants (eg, Si, Ge, Sn, Se, Te, etc.) are doped.

And a first nitride layer 110 and a second nitride layer 120 of the first conductive semiconductor layers 110 and 120, wherein the first nitride layer 110 has a lower refractive index than the second nitride layer 120. The second nitride layer 110 may be formed of a medium layer having a higher refractive index than the first nitride layer 110. The first nitride layer 110 is Al _x Ga _1-x N (0 <x≤1), and may be formed of an n-AlGaN or AlN layer, and the second nitride layer 120 is an n-GaN layer. Can be done. Here, when the emission wavelength is 450 nm, the refractive index of GaN is 2.44, and AlGaN or AlN is 2.12 to 2.44.

Here, in the case of AlGaN, the refractive index is changed to 2.12 to 2.44 according to the composition ratio of Al and Ga. When the Al content is relatively higher than that of Ga, the refractive index is lowered to increase light extraction efficiency.

The first electrode 170 is formed on the first nitride layer 110 of the first conductive semiconductor layers 110 and 120.

An active layer 130 is formed below the second nitride layer 120 of the first conductive semiconductor layers 110 and 120, and the active layer 130 is formed in a single or multiple quantum well structure, for example, an InGaN well layer. With one cycle of / GaN barrier layer, it can be formed into single or multiple quantum well structure.

A second conductive semiconductor layer 140 is formed below the active layer 130. The second conductive semiconductor layer 140 may be implemented as a p-type semiconductor layer doped with a p-type dopant (eg, Mg), and the p-type semiconductor layer may be GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN. It may be made of any one of compound semiconductors such as.

In addition, an n-type semiconductor layer (not shown) may be formed under the second conductive semiconductor layer 140. Further, in the embodiment, the first conductive semiconductor layers 110 and 120 may be p-type semiconductor layers, and the second conductive semiconductor layer 140 may be embodied as n-type semiconductor layers, but is not limited thereto.

The reflective electrode layer 150 is formed under the second conductive semiconductor layer 140. The reflective electrode layer 150 may be selectively formed of a material such as Al, Ag, Pd, Rh, Pt.

The conductive support member 160 is formed below the reflective electrode layer 150. The conductive support member 160 may be selectively formed of a material such as copper or gold. Materials of the reflective electrode layer 150 and the conductive support member 160 may be changed, but are not limited thereto.

The n-AlGaN layer or the n-AlN layer, which is the first nitride layer 110 having a low refractive index, is formed on the surface of the semiconductor light emitting device 100, so that the light emitted from the active layer 130 is transferred to the second nitride layer ( It is incident on the 120 and can be easily extracted to the outside through the first nitride layer 110. Accordingly, the brightness of the LED can be improved.

2 to 5 are views illustrating a manufacturing process of the semiconductor light emitting device according to the embodiment.

2, a buffer layer 103, first conductive semiconductor layers 110 and 120 having different refractive index layers, an active layer 130, and a second conductive semiconductor layer 140 are included on a substrate 101.

The substrate 101 may be selected from the group consisting of sapphire substrate (Al ₂ O ₃ ), GaN, SiC, ZnO, Si, GaP, InP, and GaAs. The buffer layer 103 may be formed using GaN, AlN, AlGaN, InGaN, AlInGaN, etc. to selectively reduce the lattice constant difference from the substrate 101. An undoped semiconductor layer (not shown) may be formed on the buffer layer 103, and the undoped semiconductor layer (not shown) may be implemented as an undoped GaN layer. In addition, the buffer layer 103 and the undoped semiconductor layer may not exist or at least one layer may exist on the substrate 101.

First conductive semiconductor layers 110 and 120 are formed on the buffer layer 103. The first conductive semiconductor layers 110 and 120 are n-type semiconductor layers, and have a low refractive index first nitride layer 110 formed on the buffer layer 103 and a high refractive index second nitride formed on the first nitride layer 110. Layer 120. The first nitride layer 110 may be implemented as an n-AlGaN layer or an AlN layer, and the second nitride layer 120 may be implemented as an n-GaN layer. The n-AlGaN layer 110 may have a lower refractive index, for example, according to an Al content.

In addition, by using Equation 1, the thicknesses of the first nitride layer 110 and the second nitride layer 120 may be optimized.

[Equation 1]

T = λ / (4n)

T is the thickness of each medium, λ is the wavelength, and n is the refractive index of each medium.

The active layer 130 is formed on the second nitride layer 120 of the first conductive semiconductor layers 110 and 120, and the second conductive semiconductor layer 140 is formed on the active layer 130.

Referring to FIG. 3, a reflective electrode layer 150 is formed on the second conductive semiconductor layer 140. The reflective electrode layer 150 functions as a second electrode and may be selectively formed of a material such as Al, Ag, Ag alloy, Al alloy, Ni, Pd, Rh, Pt, or the like.

Referring to FIG. 4, a conductive support member 160 is formed on the reflective electrode layer 150. The conductive support member 160 may be selectively formed of a material such as copper, gold, or a conductive substrate.

4 and 5, after the substrate 101 and the buffer layer 103 of FIG. 4 are removed by physical and chemical methods, the surface of the first nitride layer 110 among the first conductive semiconductor layers 110 and 120 may be removed. To be exposed. Here, the substrate 101 may be removed through a laser irradiation on the surface (LLO: Liser Lift Off), and the buffer layer 103 may be removed by a wet etching method and / or a dry etching method. .

The first electrode 170 is formed on the surface of the first nitride layer 110 among the first conductive semiconductor layers 110 and 120.

The first conductive semiconductor layers 110 and 120 are formed of a first nitride layer 110 having a low refractive index and a second nitride layer 120 having a high refractive index, so that light generated in the active layer 130 has a high refractive index. It may be easily released to the outside through the first nitride layer 110 having a low refractive index via the second nitride layer 120.

6 and 7 illustrate an example in which roughness is formed on a surface of a semiconductor light emitting device according to an embodiment.

As shown in FIG. 6, roughness 115 in the form of sawtooth or triangle waves is formed on the surface of the first nitride layer 110 in the first conductive semiconductor layers 110 and 120. The roughness 115 may be formed in a random period or a constant period.

As illustrated in FIG. 7, roughness 115A having surface irregularities is formed on the surfaces of the second nitride layers 110 in the first conductive semiconductor layers 110 and 120 in a periodic manner. The roughness 115A may be formed at random intervals or at regular intervals.

The roughnesses 115 and 115A may improve the external quantum efficiency by changing the optical critical angle at the surface of the first nitride layer 110.

In the description of an embodiment according to the present invention, each layer (film), region, pattern or structure is "on" or "under" the substrate, each layer (film), region, pad or patterns. In the case where it is described as being formed in, "on" and "under" include both the meanings of "directly" and "indirectly". In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

The present invention has been described above with reference to preferred embodiments thereof, which are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible that are not illustrated above. For example, each component shown in detail in the embodiment of the present invention may 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.

DESCRIPTION OF SYMBOLS 100: Semiconductor light emitting element, 101: board | substrate, 103: buffer layer, 110, 120: 1st conductive semiconductor layer, 130: active layer, 140: 2nd conductive semiconducting layer, 150: reflective electrode layer, 160: conductive support member, 170: 1st Electrode, 115, 115A: Roughness

Claims (6)

A first conductive semiconductor layer;
An electrode electrically connected to the first conductive semiconductor layer;
A second conductive semiconductor layer under the first conductive semiconductor layer;
An active layer between the first conductive semiconductor layer and the second conductive semiconductor layer; And
A reflective electrode layer under the second conductive semiconductor layer,
The first conductive semiconductor layer includes a nitride layer having a low refractive index and a nitride layer having a high refractive index,
The nitride layer of high refractive index is disposed closer to the active layer than the nitride layer of low refractive index. The semiconductor light emitting device of claim 1, further comprising a conductive support member formed under the reflective electrode layer. The semiconductor light emitting device of claim 1, wherein the second conductive semiconductor layer is a p-type semiconductor layer. 3. The method according to claim 1 or 2,
The first nitride layer includes n-type Al _x Ga _1-x N (0 <x≤1),
The second nitride layer is a semiconductor light emitting device including an n-type GaN-based material. The method of claim 1,
And a third conductive semiconductor layer between the second conductive semiconductor layer and the reflective electrode layer. The method according to claim 1 or 2,
A semiconductor light emitting device comprising roughness on an upper surface of the first conductive semiconductor layer.

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