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Semiconductor light emitting element and wafer




Title: Semiconductor light emitting element and wafer.
Abstract: There are provided a semiconductor light emitting element which allows an improvement in light extraction efficiency without increasing the number of fabrication steps, and a wafer. In a semiconductor light emitting element 1 formed by laminating a compound semiconductor layer 3 on a single crystal substrate, and dividing the single crystal substrate into pieces, the side faces 21 to 24 of each of substrate pieces 2 as the divided single crystal substrate are formed such that the side face 21 used as the reference of the substrate piece 2 forms an angle of 15° with respect to the (1-100) plane, and that the side faces 21 to 24 are formed of planes different from cleaved planes of a crystalline structure in the single crystal substrate. ...


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USPTO Applicaton #: #20100187565
Inventors: Hidenori Kamei, Syuuichi Shinagawa


The Patent Description & Claims data below is from USPTO Patent Application 20100187565, Semiconductor light emitting element and wafer.

CROSS-REFERENCE TO RELATED APPLICATIONS

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This application is a Divisional of U.S. application Ser. No. 12/298,664, filed on Oct. 27, 2008, which is a U.S. National Phase under 35 U.S.C. §371 of International Application No. PCT/JP2007/059562, filed Apr. 27, 2007, claiming priority of Japanese Patent Application No. 2006-123258, filed on Apr. 27, 2006, and Japanese Patent Application No. 2007-115554, filed Apr. 25, 2007, the entire contents of each of which are hereby incorporated by reference.

TECHNICAL FIELD

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The present invention relates to a semiconductor light emitting element in which a compound semiconductor layer is laminated on a single crystal substrate, and to a wafer.

BACKGROUND

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ART

As a technology for increasing the efficiency of light extraction from a semiconductor light emitting element, and improving brightness, there is one described in Patent Document 1. In a gallium nitride-based compound semiconductor element described in Patent Document 1, the side faces of a substrate, or the side faces of the gallium nitride-based compound semiconductor element laminated on the substrate have been each formed into a concave and convex configuration by etching.

By thus forming the emission faces from which light is emitted into concave and convex faces, the degree to which light from the inside is totally reflected by the surfaces thereof can be reduced compared with the case where the emission faces are formed into flat and smooth faces, so that an improvement in light extraction efficiency is expected. Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-6662

DISCLOSURE OF THE INVENTION

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Problems to be Solved by the Invention

However, in the gallium nitride-based compound semiconductor element described in Patent Document 1, the side faces of the substrate or the side faces of a gallium nitride-based compound semiconductor laminated on the substrate have been each formed into the concave and convex configuration by etching. Therefore, after the gallium nitride-based compound semiconductor is laminated on the substrate in a fabrication step thereof, it is necessary to add an etching step. This not only complicates the fabrication steps, but also increases fabrication cost. Additionally, in this method, concaves and convexes are reduced as the depth of etching is increased so that it is difficult to form the concave and convex configuration over the entire surfaces.

It is therefore an object of the present invention to provide a semiconductor light emitting element which allows an improvement in light extraction efficiency by forming concaves and convexes over the entire side faces of the semiconductor light emitting element without increasing the number of fabrication steps, and a wafer.

Means for Solving the Problems

A semiconductor light emitting element of the present invention is a semiconductor light emitting element formed by laminating a compound semiconductor layer on a single crystal substrate, and dividing the single crystal substrate into pieces, wherein the single crystal substrate has a hexagonal structure, and the side faces of the divided single crystal substrate are formed of planes different from the cleaved planes of the single crystal substrate.

A wafer of the present invention is a wafer which is a single crystal substrate on which a compound semiconductor layer forming a semiconductor light emitting element is laminated, wherein the single crystal substrate has a hexagonal structure, and an OF (Oriented Flat) surface indicative of the crystal direction of the single crystal substrate is formed of a plane different from cleaved planes.

In a preferred embodiment, a plane of the single crystal substrate on which the compound semiconductor layer is laminated is a (0001) plane.

In another preferred embodiment, a plane of the single crystal substrate on which the compound semiconductor layer is laminated is an a-plane, and a c-plane and an m-plane each orthogonal to the a-plane are the cleaved planes of the single crystal substrate. The a-plane indicates a plane with a (11-20) plane orientation, or a (1-210) plane or a (−2110) plane which is equivalent to the (11-20) plane. The c-plane indicates a plane with a (0001) orientation. The m-plane indicates a plane with a (1-100) plane orientation, or a (01-10) plane or a (10-10) plane which is equivalent to the (1-100) plane. More strictly, the sign of a numeral representing a plane orientation is different at a top side plane than at a back side plane. However, it is assumed in the present invention that, e.g., the (11-20) plane indicates both of the (11-20) plane and a (−1-120) plane. The c-plane is in orthogonal relation to all the a-planes and the m-planes. As combinations in each of which the a-plane is orthogonal to the m-plane, there are three combinations in which the a-planes and the m-planes are (11-20) and (1-100), (1-210) and (10-10), and (-2110) and (01-10), respectively. In the present invention, the three combinations in which the a-planes and the m-planes are orthogonal to each other will be mentioned hereinbelow.

Effect of the Invention

In the present invention, it is sufficient that the side faces of the single crystal substrate are formed of planes different from the cleaved planes. Accordingly, it is unnecessary to add a new fabrication step in order to improve light extraction efficiency. Therefore, a semiconductor element with high brightness efficiency can be provided without increasing fabrication cost.

BRIEF DESCRIPTION OF THE DRAWINGS

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FIG. 1 is a cross-sectional view showing a semiconductor light emitting element according to Embodiment 1;

FIG. 2 is a view showing a wafer according to Embodiment 1, and a compound semiconductor layer and electrodes each formed on the wafer;

FIG. 3 is a perspective view showing the wafer according to Embodiment 1;

FIG. 4(A) is a view showing the surface roughness of a side face of a semiconductor light emitting element according to Example 1, and FIG. 4(B) is a view showing the surface roughness of a side face of Comparative Example 1 as a conventional semiconductor light emitting element;

FIG. 5 is a view showing a conventional wafer according to Comparative Example 1, and a compound semiconductor layer and electrodes each formed on the wafer;

FIG. 6(A) is a drawing-substitute photograph in which a side face of the semiconductor light emitting element according to Example 1 is enlarged, FIG. 6(B) is a drawing-substitute photograph in which another side face of the semiconductor light emitting element according to Example 1 is enlarged, FIG. 6(C) is a drawing-substitute photograph in which a side face of Comparative Example 1 as the conventional semiconductor light emitting element is enlarged, and FIG. 6(D) is a drawing-substitute photograph in which another side face of the conventional semiconductor light emitting element of Comparative Example 1 is enlarged;

FIG. 7 a cross-sectional view showing a semiconductor light emitting element according to Embodiment 2;

FIG. 8 is a view showing a wafer according to Embodiment 2, and a compound semiconductor layer and electrodes each formed on the wafer;

FIG. 9 is a perspective view showing the wafer according to Embodiment 2;

FIG. 10(A) is a view showing the surface roughness of a side face of a semiconductor light emitting element according to Example 2, and FIG. 10(B) is a view showing the surface roughness of a side face of Comparative Example 2 as a conventional semiconductor light emitting element; and




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stats Patent Info
Application #
US 20100187565 A1
Publish Date
07/29/2010
Document #
File Date
12/31/1969
USPTO Class
Other USPTO Classes
International Class
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Drawings
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Active Solid-state Devices (e.g., Transistors, Solid-state Diodes)   Incoherent Light Emitter Structure   With Particular Semiconductor Material  

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20100729|20100187565|semiconductor light emitting element and wafer|There are provided a semiconductor light emitting element which allows an improvement in light extraction efficiency without increasing the number of fabrication steps, and a wafer. In a semiconductor light emitting element 1 formed by laminating a compound semiconductor layer 3 on a single crystal substrate, and dividing the single |Panasonic-Corporation
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