KR20100049274A

KR20100049274A - Nitride semiconductor light emitting device and method of manufacturing the same

Info

Publication number: KR20100049274A
Application number: KR1020080108373A
Authority: KR
Inventors: 우종균; 이수열; 장태성
Original assignee: 삼성엘이디 주식회사
Priority date: 2008-11-03
Filing date: 2008-11-03
Publication date: 2010-05-12

Abstract

PURPOSE: A nitride semiconductor light emitting device and a method for manufacturing the same are provided to improve an optical extraction efficiency of the device by forming an air layer in the lower side of a buffer layer in order to totally reflect light which is toward to a substrate. CONSTITUTION: An air layer is formed in a buffer layer(120). An n-type nitride semiconductor layer(130) is formed on the buffer layer. An active layer(140) is formed on the n-type nitride semiconductor layer. A p-type nitride semiconductor layer(150) is formed on the active layer. A p-type electrode(160) is formed on the p-type nitride semiconductor layer. An n-type electrode(170) is formed on the n-type nitride semiconductor layer.

Description

Nitride semiconductor light emitting device and method of manufacturing the same

The present invention relates to a nitride semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a nitride semiconductor light emitting device having an air layer formed inside the buffer layer and a method of manufacturing the same.

Recently, III-V nitride semiconductors such as GaN have been spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their excellent physical and chemical properties. have. LEDs or LDs using III-V nitride semiconductor materials are widely used in light emitting devices for obtaining light in the blue or green wavelength band, and these light emitting devices are used as light sources of various products such as home appliances, electronic displays, and lighting devices. Here, the group III-V nitride semiconductor is usually made of a GaN-based material having a composition formula of In _X Al _Y Ga _1-XY N (0≤X, 0≤Y, X + Y≤1).

In general, the light efficiency of a nitride semiconductor light emitting device is determined by an internal quantum efficiedncy and an external light extraction efficiency (also called "external quantum efficiency"). In particular, the external light extraction efficiency is determined by optical factors of the light emitting device, that is, the refractive index of each structure and / or the flatness of the interface.

In view of the light extraction efficiency, the nitride semiconductor light emitting device has a fundamental limitation. That is, since the semiconductor layer constituting the conventional nitride semiconductor light emitting device has a large refractive index compared to the external atmosphere or the substrate, the critical angle that determines the range of incidence angle of light emission becomes small, and as a result, a large part of the light generated from the active layer It is totally internally reflected and propagated in a substantially undesired direction or lost in the total reflection process, so the light extraction efficiency is low.

Accordingly, there is a continuous need for a method of improving light extraction efficiency of a nitride semiconductor light emitting device by reducing the amount of light lost inside the device.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to form a nitride semiconductor light emitting device that can improve the light extraction efficiency of the device by forming an air layer below the buffer layer formed on the substrate and It is to provide a method of manufacturing the same.

A nitride semiconductor light emitting device according to an embodiment of the present invention for achieving the above object, a substrate; A buffer layer formed on the substrate and having an air layer therein; An n-type nitride semiconductor layer formed on the buffer layer; An active layer formed on a portion of the n-type nitride semiconductor layer; A p-type nitride semiconductor layer formed on the active layer; A p-type electrode formed on the p-type nitride semiconductor layer; And an n-type electrode formed on the n-type nitride semiconductor layer.

Here, the air layer may be formed in the lower central portion of the buffer layer.

In addition, the method of manufacturing a nitride semiconductor light emitting device according to an embodiment of the present invention for achieving the above object comprises the steps of sequentially forming a buffer layer, an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer on a substrate; Mesa-etching a portion of the p-type nitride semiconductor layer and the active layer to expose a portion of the n-type nitride semiconductor layer; Forming a p-type electrode and an n-type electrode on the p-type nitride semiconductor layer and the exposed n-type nitride semiconductor layer, respectively; And removing a portion of the buffer layer in contact with the substrate by irradiating a laser from a lower portion of the substrate to form an air layer.

The buffer layer may be made of a GaN-based material.

In addition, the laser may be a KrF or ArF laser.

Further, in the step of irradiating a laser from the lower portion of the substrate to remove a portion of the buffer layer in contact with the substrate to form an air layer, the laser is selectively irradiated to a position corresponding to the central portion of the buffer layer, the air layer The buffer layer may be formed at a lower central portion of the buffer layer.

As described above, according to the nitride semiconductor light emitting device and the method of manufacturing the same according to the present invention, by forming an air layer below the buffer layer formed on the substrate, the total light reflected toward the substrate from the light generated in the active layer is upwardly reflected. It is possible to improve the light extraction efficiency of the device.

Therefore, the present invention can improve the light emitting characteristics of the device.

The matters relating to the operational effects including the technical constitution for the above object of the nitride semiconductor light emitting device and the manufacturing method according to the present invention will be clearly understood by the following detailed description with reference to the drawings in which preferred embodiments of the present invention are shown.

Structure of nitride semiconductor light emitting device

A nitride semiconductor light emitting device according to an embodiment of the present invention will be described in detail with reference to FIG. 1.

1 is a cross-sectional view showing the structure of a nitride semiconductor light emitting device according to an embodiment of the present invention.

As shown in FIG. 1, the nitride semiconductor light emitting device according to the embodiment of the present invention includes a buffer layer 120, an n-type nitride semiconductor layer 130, an active layer 140, and a p-type nitride semiconductor on a substrate 110. Layers 150 are sequentially stacked.

The substrate 110 is preferably made of a transparent material such as sapphire, and in addition to sapphire, zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (SiC) or aluminum nitride (AlN) or the like.

The buffer layer 120 is a layer for improving lattice matching with the substrate 100 before growing the n-type nitride semiconductor layer 120 on the substrate 100, and may be formed of a GaN-based material or the like.

In particular, in the nitride semiconductor light emitting device according to the embodiment of the present invention, an air layer 200 is formed in the buffer layer 120 formed on the substrate 110. In this case, the air layer 200 is to totally reflect the light toward the substrate 110 from the light generated from the active layer 140 to the top, it is preferably formed in the lower central portion of the buffer layer 120. Do.

The n-type nitride semiconductor layer 130, the active layer 140, and the p-type nitride semiconductor layer 150 may have an In _X Al _Y Ga _1-XY N composition formula (where 0 ≦ X, 0 ≦ Y, and X + Y ≦ It can be made of a semiconductor material having 1).

More specifically, the n-type nitride semiconductor layer 130 may be formed of a GaN layer or a GaN / AlGaN layer doped with n-type conductive impurities, for example, Si, Ge, Sn is used, and preferably Si is mainly used.

In addition, the p-type nitride semiconductor layer 150 may be formed of a GaN layer or a GaN / AlGaN layer doped with a p-type conductive impurities, for example, Mg, Zn, Be, etc. Is used, and preferably Mg is mainly used.

In addition, the active layer 140 may be formed of an InGaN / GaN layer having a multi-quantum well structure.

A portion of the p-type nitride semiconductor layer 150 and the active layer 140 are removed by mesa etching to expose a portion of the n-type nitride semiconductor layer 130.

The p-type electrode 160 is formed on the p-type nitride semiconductor layer 150 which is not removed by the mesa etching.

An n-type electrode 170 is formed on the n-type nitride semiconductor layer 130 exposed by the mesa etching, that is, the n-type nitride semiconductor layer 130 on which the active layer 140 is not formed.

The p-type electrode 160 and the n-type electrode 170 may be formed of Au, Cr / Au, or the like to simultaneously serve as a reflection role and an electrode.

In addition, before the p-type electrode 160 is formed on the upper surface of the p-type nitride semiconductor layer 150, a transparent electrode (not shown) may be formed to form an ohmic contact while increasing a current injection area. The transparent electrode is mainly made of indium tin oxide (ITO).

In the nitride semiconductor light emitting device according to the embodiment of the present invention, as described above, the air layer 200 is formed in the lower central portion of the buffer layer 120 formed on the substrate 110.

Here, the refractive index of the GaN semiconductor material constituting the buffer layer 120 is about 2.4, and when the sapphire substrate 110 is formed under the buffer layer 120, the refractive index of the sapphire substrate 110 is about 1.77. In this case, since the refractive index of the air layer 200 is 1, the difference in refractive index between the buffer layer 120 and the air layer 200 is greater than the difference in refractive index between the buffer layer 120 and the sapphire substrate 110.

In general, the larger the difference in refractive index between adjacent materials, the smaller the critical angle is, thereby increasing the total reflection efficiency. In the exemplary embodiment of the present invention, since the air layer 200 is further formed below the buffer layer 120, the active layer 140 Among the light generated from the light source, the light directed toward the substrate 110 may not be lost inside the device, but may be totally reflected by the air layer 200 and may exit to the top of the device.

Therefore, according to the embodiment of the present invention, the light extraction efficiency of the nitride semiconductor light emitting device is increased, thereby improving the light emitting characteristics of the device.

Method of manufacturing nitride semiconductor light emitting device

A method of manufacturing a nitride semiconductor light emitting device according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 to 5.

2 to 5 are cross-sectional views sequentially showing the method of manufacturing the nitride semiconductor light emitting device according to the embodiment of the present invention.

First, as shown in FIG. 2, the buffer layer 120, the n-type nitride semiconductor layer 130, the active layer 140, and the p-type nitride semiconductor layer (on the substrate 110 for growth of GaN-based semiconductor material) 150) are formed in sequence.

The buffer layer 120 may be made of a GaN-based material or the like.

In general, the buffer layer 120, the n-type nitride semiconductor layer 130, the active layer 140, and the p-type nitride semiconductor layer 150 may be epitaxially prepared using a metal organic chemical vapor deposition (MOCVD) facility. It may be formed through epitaxial growth.

Next, as shown in FIG. 3, a portion of the n-type nitride semiconductor layer 130 is exposed by mesa etching the p-type nitride semiconductor layer 150 and a portion of the active layer 140.

Then, as illustrated in FIG. 4, a p-type electrode 160 is formed on the p-type nitride semiconductor layer 150 which is not etched by the mesa etching process, and the n is revealed by the mesa etching process. The n-type electrode 170 is formed on the type nitride semiconductor layer 130. In this case, before the p-type electrode 160 is formed on the p-type nitride semiconductor layer 150, a transparent electrode such as ITO may be further formed.

Next, as shown in FIG. 5, a portion of the buffer layer 120 contacting the substrate 110 is removed by irradiating a laser from the lower portion of the substrate 110 to form an air layer 200.

In this case, when the laser is irradiated to the entire lower portion of the substrate 110, since the substrate 110 may be completely separated from the buffer layer 120, the laser is not irradiated to the entire lower portion of the substrate 110. Instead, it selectively irradiates only to a position corresponding to the central portion of the buffer layer 120, so that the air layer 200 may be formed at the lower central portion of the buffer layer 120.

As the laser for forming the air layer 200, a KrF or ArF laser may be used. When the laser is irradiated from the lower portion of the substrate 110, the laser forms the buffer layer 120. A portion of the buffer layer 120 is removed while reacting with GaN to generate Ga and N ₂ gases to form an air layer 200.

In the nitride semiconductor light emitting device according to the embodiment of the present invention, by forming the air layer 200 inside the buffer layer 120 on the substrate 110, most of the light from the active layer 140 to the substrate 110 is the air The total reflection at the layer 200 may increase the light extraction efficiency of the device.

Preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and various substitutions, modifications, and changes within the scope without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It will be possible, but such substitutions, changes and the like should be regarded as belonging to the following claims.

2 to 5 are cross-sectional views sequentially showing the method for manufacturing the nitride semiconductor light emitting device according to the embodiment of the present invention.

110: sapphire substrate 120: buffer layer

130: n-type nitride semiconductor layer 140: active layer

150: p-type nitride semiconductor layer 160: p-type electrode

170: n-type electrode 200: air layer

Claims

Board;

A buffer layer formed on the substrate and having an air layer therein;

An n-type nitride semiconductor layer formed on the buffer layer;

An active layer formed on a portion of the n-type nitride semiconductor layer;

A p-type nitride semiconductor layer formed on the active layer;

A p-type electrode formed on the p-type nitride semiconductor layer; And

An n-type electrode formed on the n-type nitride semiconductor layer;

Nitride semiconductor light emitting device comprising a.

The method of claim 1,

The air layer is a nitride semiconductor light emitting device formed on the lower central portion of the buffer layer.

Sequentially forming a buffer layer, an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer on the substrate;

Mesa-etching a portion of the p-type nitride semiconductor layer and the active layer to expose a portion of the n-type nitride semiconductor layer;

Forming a p-type electrode and an n-type electrode on the p-type nitride semiconductor layer and the exposed n-type nitride semiconductor layer, respectively; And

Irradiating a laser under the substrate to remove a portion of the buffer layer in contact with the substrate to form an air layer;

Method of manufacturing a nitride semiconductor light emitting device comprising a.

The method of claim 3,

The buffer layer is a method of manufacturing a nitride semiconductor light emitting device made of a GaN-based material.

The method of claim 3,

The laser is a KrF or ArF laser manufacturing method of nitride semiconductor light emitting device.

The method of claim 3,

Irradiating a laser under the substrate to remove a portion of the buffer layer in contact with the substrate to form an air layer,

And the air is selectively irradiated at a position corresponding to the central portion of the buffer layer, such that the air layer is formed at the lower central portion of the buffer layer.