Lighting emitting diode with light extracted from front and back sides of a lead frame

• US 9,859,464 B2
• Filed: 12/23/2015
• Issued: 01/02/2018
• Est. Priority Date: 11/15/2006
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: DeMille, Natalie Fellows, DenBaars, Steven P., Nakamura, Shuji
• Primary Examiner(s): Nguyen, Cuong Q
• Application Number:
  US14/757,937
• Publication Number:
  US 20160133790A1
• Time in Patent Office: 741 Days
• Field of Search: 257 13
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• 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 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H01L 33/60 : Reflective elements
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

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 and phosphor layer 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 shaped optical element.

Claims

1. A light emitting device, comprising:

a lead frame including a transparent plate; and

an LED chip, attached to the lead frame, for emitting light;

wherein the LED chip resides on or above the transparent plate and at least some of the light emitted by the LED chip is transmitted through the transparent plate; and

wherein at least a portion of the light emitted by the LED chip is extracted from a front side of the lead frame and another portion of the light emitted by the LED chip is extracted from a back side of the lead frame.

2. The device of claim 1, further comprising a phosphor for converting a wavelength of the light.

3. The device of claim 2, wherein at least a portion of the phosphor is roughened, textured, or patterned to minimize internal reflection of the light within the phosphor.

4. The device of claim 1, further comprising a shaped optical element formed on or around the LED chip, wherein the shaped optical element is transparent to the light.

5. The device of claim 4, wherein a phosphor is located on top of the shaped optical element, within the shaped optical element, or near a surface of the shaped optical element.

6. The device of claim 1, further comprising a mirror for reflecting the light away from the LED chip.

7. The device of claim 1, wherein the transparent plate is roughened, textured or patterned to increase transmission of the light through the transparent plate.

8. The device of claim 1, wherein one or more surfaces of the LED chip are roughened, textured or patterned to increase extraction of the light from the LED chip.

9. The device of claim 1, wherein the LED chip includes a transparent substrate positioned adjacent the transparent plate.

10. The device of claim 9, wherein the transparent substrate is roughened, textured, or patterned, to increase extraction of the light from the LED chip.

11. A method of fabricating a light emitting device, comprising:

providing a lead frame including a transparent plate; and

attaching an LED chip, for emitting light, to the lead frame;

wherein the LED chip reside on or above the transparent plate and at least some of the light emitted by the LED chip is transmitted through the transparent plate; and

wherein at least a portion of the light emitted by the LED chip is extracted from a front side of the lead frame and another portion of the light emitted by the LED chip is extracted from a back side of the lead frame.

12. The method of claim 11, further comprising providing a phosphor for converting a wavelength of the light.

13. The method of claim 12, wherein at least a portion of the phosphor is roughened, textured, or patterned to minimize internal reflection of the light within the phosphor.

14. The method of claim 11, further comprising forming a shaped optical element on or around the LED chip, wherein the shaped optical element is transparent to the light.

15. The method of claim 14, wherein a phosphor is located on top of the shaped optical element, within the shaped optical element, or near a surface of the shaped optical element.

16. The method of claim 11, further comprising providing a mirror for reflecting the light away from the LED chip.

17. The method of claim 11, wherein the transparent plate is roughened, textured or patterned to increase transmission of the light through the transparent plate.

18. The method of claim 11, wherein one or more surfaces of the LED chip are roughened, textured or patterned to increase extraction of the light from the LED chip.

19. The method of claim 11, wherein the LED chip includes a transparent substrate positioned adjacent the transparent plate.

20. The method of claim 19, wherein the transparent substrate is roughened, textured, or patterned, to increase extraction of the light from the LED chip.