Light-emitting device having a patterned surface

• US 10,181,549 B2
• Filed: 11/22/2017
• Issued: 01/15/2019
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: Epistar Corporation (Ennostar, Inc.)
• Inventors: Ou, Chen, Yao, Chiu-Lin
• Primary Examiner(s): Schoenholtz, Joseph
• Application Number:
  US15/821,147
• Publication Number:
  US 20180108808A1
• Time in Patent Office: 419 Days
• Field of Search: None
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• 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 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A light-emitting device comprises a substrate having a top surface and a plurality of patterned units protruding from the top surface; and a light-emitting stack formed on the substrate and having an active layer with a first surface substantially parallel to the top surface, wherein one of the plurality of patterned units comprises a plurality of connecting sides constituting a first polygon shape in a top view of the light-emitting device, wherein the one of the plurality of patterned units comprises a vertex and a plurality of inclined surfaces respectively extending from the plurality of connecting sides, the plurality of inclined surfaces commonly joining at the vertex in a cross-sectional view of the light-emitting device, the vertex being between the top surface of the substrate and the first surface of the active layer, and the plurality of inclined surfaces comprises a second polygon shape in the cross-sectional view of the light-emitting device.

Claims

1. A light-emitting device comprising:

a substrate having a top surface and a plurality of patterned units protruding from the top surface of the substrate; and

a light-emitting stack formed on the substrate and having an active layer with a first surface substantially parallel to the top surface of the substrate,

wherein each of the plurality of patterned units comprises a circular shape in a top view of the light-emitting device,

wherein the plurality of patterned units comprises two curves with different curvatures in a cross-sectional view of the light-emitting device.

2. The light-emitting device according to claim 1, wherein the plurality of patterned units is not parallel to the first surface of the active layer.

3. The light-emitting device according to claim 1, wherein the plurality of patterned units comprises a semicircle shape or an arc shape in the cross-sectional view of the light-emitting device.

4. The light-emitting device according to claim 1, wherein one of the plurality of patterned units comprises a width and a depth smaller than the width.

5. The light-emitting device according to claim 1, wherein one of the plurality of patterned units contacts with another one of the plurality of patterned units.

6. The light-emitting device according to claim 1, wherein the plurality of patterned units comprises different diameters in a top view of the light-emitting device.

7. The light-emitting device according to claim 1, wherein one of the plurality of patterned units comprises a mesa on a top surface of the one of the plurality of patterned units.

8. The light-emitting device according to claim 1, wherein one of the plurality of patterned units comprises a vertex, a first inclined line segment and a second inclined line segment, the first inclined line segment and the second inclined line segment connect at the vertex in the cross-sectional view of the light-emitting device.

9. The light-emitting device according to claim 8, wherein vertices of the plurality of patterned units constitute vertices of a triangular shape.

10. The light-emitting device according to claim 1, wherein the substrate comprises GaP, sapphire, GaN, or AlN.

11. A light-emitting device comprising:

a substrate having a top surface and a plurality of patterned units protruding from the top surface; and

a light-emitting stack formed on the substrate and having an active layer with a first surface substantially parallel to the top surface of the substrate,

wherein one of the plurality of patterned units comprises a plurality of connecting sides constituting a first polygon shape in a top view of the light-emitting device,

wherein the one of the plurality of patterned units comprises a vertex and a plurality of inclined surfaces respectively extending from the plurality of connecting sides, the plurality of inclined surfaces commonly joining at the vertex in a cross-sectional view of the light-emitting device, the vertex being between the top surface of the substrate and the first surface of the active layer, and the plurality of inclined surfaces comprises a second polygon shape in the cross-sectional view of the light-emitting device.

12. The light-emitting device according to claim 11, wherein the plurality of inclined surfaces is substantially not parallel to the first surface of the active layer.

13. The light-emitting device according to claim 11, wherein the plurality of patterned units is disposed in a variable period.

14. The light-emitting device according to claim 11, wherein the plurality of patterned units is periodically arranged on the substrate.

15. The light-emitting device according to claim 11, further comprising an undoped semiconductor layer formed on the substrate and enclosing the plurality of patterned units.

16. The light-emitting device according to claim 11, wherein one of the plurality of patterned units comprises a width and a depth smaller than the width.

17. The light-emitting device according to claim 11, wherein the substrate comprises a non-patterned area parallel to the first surface and the non-patterned area is not greater than 10% of a total area of the substrate.

18. The light-emitting device according to claim 11, further comprising a neighboring material with a refraction index different from that of the substrate.

19. The light-emitting device according to claim 11, wherein one of the plurality of patterned units contacts with another one of the plurality of patterned units.

20. The light-emitting device according to claim 11, wherein the first polygon shape comprises a triangle, a rectangle, or a hexagon.