HIGH LIGHT EXTRACTION EFFICIENCY SPHERE LED

• US 20080121918A1
• Filed: 11/15/2007
• Published: 05/29/2008
• Est. Priority Date: 11/15/2006
• Status: Abandoned Application

• Current Assignee: Japan Science And Technology Agency
• Original Assignee: Regents of the University of California (University of California)
• Inventors: DenBaars, Steven P., Nakamura, Shuji, Masui, Hisashi
• Application Number:
  US11/940,872
• Publication Number:
  US 20080121918A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/16245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• 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 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

This invention is related to LED Light Extraction for optoelectronic applications. More particularly the invention relates to (Al, Ga, In)N combined with optimized optics for highly efficient (Al, Ga, In)N based light emitting diodes applications, and its fabrication method. A further extension is the general combination of a shaped high refractive index light extraction material combined with a sphere shaped molding.

Claims

1. A Light Emitting Diode (LED), comprising:

a LED chip, the LED chip emitting light at least a first emission wavelength; and

a package, surrounding the LED chip, wherein the package has a substantially spherical shape.

2. The LED of claim 1, wherein the LED chip is located substantially at the center of the package.

3. The LED of claim 1, wherein the package is made from a material that is transparent at the emission wavelength of the LED chip.

4. The LED of claim 1, wherein a transparent conductor layer is placed on a p-type AlGaInN layer of the LED.

5. The LED of claim 4, wherein the transparent conductor layer is made from a material selected from a group comprising Indium Tin Oxide (ITO) and Zinc Oxide (ZnO).

6. The LED of claim 4, wherein the surface of the transparent conductor layer is roughened.

7. The LED of claim 4, wherein a current spreading layer is deposited before the transparent conductor layer.

8. The LED of claim 7, wherein the current spreading layer is made from a material selected from a group comprising SiO2, SiN, and other insulating materials.

9. The LED of claim 1, wherein at least one surface of the LED chip is roughened.

10. The LED of claim 1, wherein the LED chip emits light from more than one side of the LED chip.

11. The LED of claim 1, wherein the LED chip is fabricated on a sapphire substrate, wherein a back side of the sapphire substrate is roughened.

12. The LED of claim 1, further comprising a phosphor layer, coupled to the package, wherein the phosphor layer is located remotely from the LED chip.

13. The LED of claim 1, wherein the LED chip is attached to a lead frame, the lead frame allowing for emission of light from opposite directions of the LED chip.

14. The LED of claim 1, wherein the LED chip is made from a material selected from a group comprising a (Al, Ga, In)N material system, a (Al, Ga, In)As material system, a (Al, Ga, In)P material system, a (Al, Ga, In)AsPNSb material system, a ZnGeN2 material system, and a ZnSnGeN2 material system.

15. The LED of claim 10, further comprising a mirror, optically coupled to the LED chip, wherein light emitted from one side of the LED chip is reflected to substantially align with light emitted from another side of the LED chip.

16. A Light Emitting Diode (LED), comprising:

a group-III nitride based emission source, comprising

an active layer and a textured surface layer, for emission of light in a first direction; and

a second surface layer, opposite that of the textured surface layer, for emission of light in a second direction substantially opposite that of the first direction; and

an encapsulation material, surrounding the group-III nitride based emission source, wherein the encapsulation material is substantially spherically shaped, a diameter of the encapsulation material being substantially larger than a width of the group-III nitride based emission source.

17. The LED of claim 16, wherein the second surface layer is textured.

18. The LED of claim 17, further comprising a phosphor layer, coupled to the encapsulation material, wherein light emitted from the LED excites the phosphor.

19. The LED of claim 16, further comprising a transparent conductive layer, coupled to the active layer, wherein the active layer emits light through the transparent conductive layer.

20. The LED of claim 19, wherein the transparent conductive layer is made from a material selected from a group comprising Indium Tin Oxide and Zinc Oxide.