Semiconductor light emitting device

• US 8,299,486 B2
• Filed: 06/30/2010
• Issued: 10/30/2012
• Est. Priority Date: 07/24/2001
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Niki, Isamu, Yamada, Motokazu, Sano, Masahiko, Shioji, Shuji
• Primary Examiner(s): Sefer, A.
• Application Number:
  US12/827,486
• Publication Number:
  US 20100264445A1
• Time in Patent Office: 853 Days
• Field of Search: 257/95, 257/98, 257/103, 257/117, 257/594
• US Class Current: 257/98
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02647 Lateral overgrowth
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/26 Materials of the light emitting region
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

A semiconductor light emitting device including a substrate, an electrode and a light emitting region is provided. The substrate may have protruding portions formed in a repeating pattern on substantially an entire surface of the substrate while the rest of the surface may be substantially flat. The cross sections of the protruding portions taken along planes orthogonal to the surface of the substrate may be semi-circular in shape. The cross sections of the protruding portions may in alternative be convex in shape. A buffer layer and a GaN layer may be formed on the substrate.

Claims

1. A semiconductor light emitting device comprising:

a C plane (0001) sapphire substrate comprising a plurality of protrusions that are disposed on a surface of the sapphire substrate in a two-dimensionally repeated pattern;

a plurality of GaN-based semiconductor layers epitaxially grown on the sapphire substrate; and

an ohmic electrode formed on the GaN-based semiconductor layers,

wherein the semiconductor light emitting device is configured so that light generated in the GaN-based semiconductor layers is emitted from the ohmic electrode or the sapphire substrate,

the protrusions are configured to scatter or diffract light generated in the semiconductor layers,

the repeated pattern of the protrusions is such that six protrusions forming a hexagon surround another protrusion,

in plan view of the sapphire substrate the hexagon has sides that are parallel to A-axis of the sapphire substrate, and

in plan view of the sapphire substrate the protrusions have a shape of a triangle having sides that are not parallel to A-axis of the GaN-based semiconductor layers.

2. The semiconductor light emitting device of claim 1, wherein the another triangle surrounded by the six triangles forming the hexagon and the six triangles of the hexagon are oriented in the same way in plan view of the sapphire substrate.

3. The semiconductor light emitting device of claim 1, wherein all triangles are arranged in the same direction.

4. The semiconductor light emitting device of claim 1, wherein in plan view of the sapphire substrate the triangles have sides that are perpendicular to A-axis of the GaN-based semiconductor layers.

5. The semiconductor light emitting device of claim 1, wherein a pitch of the two-dimensionally repeated pattern is greater than or equal to λ

/4 and less than or equal to 10 μ

m, where λ

is a wavelength of light emitted from the GaN based semiconductor layers.

6. The semiconductor light emitting device of claim 1, wherein a size of the protrusions is greater than or equal to λ

/4 and less than or equal to 20 μ

m, where λ

is a wavelength of light generated in the GaN based semiconductor layers.

7. The semiconductor light emitting device of claim 1, wherein in a sectional view of semiconductor light emitting device side surfaces of the protrusions incline relative to the primary surface of the sapphire substrate.

8. The semiconductor light emitting device of claim 7, wherein an inclination angle of the side surfaces is more than 105 degrees and not more than 150 degrees.

9. The semiconductor light emitting device of claims 1, 2, 3, 4, 5, 6, 7 or 8 wherein the triangle is rounded.