PIXELATED LED

• US 20120119237A1
• Filed: 07/27/2010
• Published: 05/17/2012
• Est. Priority Date: 07/30/2009
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Leatherdale, Catherine A., Yang, Zhaohui zy
• Granted Patent: US 9,196,653 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/50 Wavelength conversion elements

Abstract

A pixelated light emitting diode (LED) and a method for pixelating an LED are described. The pixelated LED includes two or more monolithically integrated electroluminescent elements disposed adjacent each other on a substrate, wherein at least a portion of each electroluminescent element immediately adjacent the substrate includes an inverted truncated pyramidal shape. The method for pixelating an LED includes selectively removing material from the major surface of an LED to a depth below the emissive region, thereby forming an array of inverted truncated pyramid shapes. The efficiency of the pixelated LEDs can be improved by incorporating the truncated pyramidal shape. Additionally, the crosstalk between adjacent LED pixels can be reduced by incorporating the truncated pyramidal shape.

Claims

1. A pixelated light emitting diode (LED), comprising:

two or more monolithically integrated electroluminescent elements disposed adjacent each other on a substrate, each electroluminescent element comprising;

a p-doped semiconductor disposed adjacent the substrate;

an n-doped semiconductor disposed adjacent the p-doped semiconductor, opposite the substrate; and

an emissive region between the n-doped semiconductor and the p-doped semiconductor,

wherein at least a portion of each electroluminescent element immediately adjacent the substrate comprises an inverted truncated pyramidal shape.

3. The pixelated LED of claim 1, wherein an angle between the substrate and a side of the inverted truncated pyramidal shape ranges from about 35 degrees to about 70 degrees.

4. The pixelated LED of claim 1, each electroluminescent element further comprising a first electrode between the substrate and the p-doped semiconductor, and an opposing light emitting surface adjacent the n-doped semiconductor, wherein the light emitting surface comprises a second electrode.

7. The pixelated LED of claim 4, wherein the emissive region is positioned closer to the first electrode than to the light emitting surface.

9. The pixelated LED of claim 7, wherein a distance between the emissive region and the first electrode ranges from about 150 nm to about 250 nm.

13. The pixelated LED of claim 4, further comprising a color converter disposed adjacent the light emitting surface of each electroluminescent element.

14. The pixelated LED of claim 13, wherein each color converter comprises a potential well.

15. The pixelated LED of claim 14, wherein the potential well comprises a group II-VI or a group III-V semiconductor.

2. (canceled)

5-6. -6. (canceled)

8. (canceled)

10-12. -12. (canceled)

16. (canceled)

17. A pixelated light emitting diode (LED), comprising:

two or more monolithically integrated electroluminescent elements disposed adjacent each other on a substrate, each electroluminescent element comprising a p-n junction having a first major light emitting surface and a smaller opposing second major surface adjacent the substrate.

18. The pixelated LED of claim 17, wherein each electroluminescent element includes a cross-sectional area parallel to the substrate, increasing along a direction perpendicular to the substrate for a portion of a distance from the second major surface to the first major light emitting surface.

19. The pixelated LED of claim 17, wherein each p-n junction comprises a quantum well positioned closer to the second major surface than to the first major light emitting surface.

21. The pixelated LED of claim 17, wherein an angle between the substrate and a side of each electroluminescent element ranges from about 35 degrees to about 70 degrees.

25. The pixelated LED of claim 19, wherein a distance between the quantum well and the second major surface from about 150 nm to about 250 nm.

29. The pixelated LED of claim 17, further comprising a color converter disposed adjacent the first major light emitting surface of each electroluminescent element.

30. The pixelated LED of claim 29, wherein each color converter comprises a potential well.

31. The pixelated LED of claim 30, wherein the potential well comprises a group II-VI or a group III-V semiconductor.

20. (canceled)

22-24. -24. (canceled)

26-28. -28. (canceled)

32. (canceled)

33. A pixelated LED, comprising:

two or more monolithically integrated electroluminescent elements disposed adjacent each other on a substrate, each electroluminescent element comprising a p-n junction having a first major light emitting surface and an opposite second major surface adjacent the substrate, wherein the substrate between immediately adjacent second major surfaces includes a surface that absorbs visible light.

34. The pixelated LED of claim 33, wherein each electroluminescent element includes an increasing cross-sectional area parallel to the second major surface, for at least a portion of a distance from the second major surface to the light emitting surface.

35-50. -50. (canceled)

51. A method for pixelating an LED, comprising:

providing a slab p-n junction on a first substrate, the slab p-n junction including a major surface opposite the first substrate, and an emissive region parallel to the major surface;

selectively removing material from the major surface to a depth below the emissive region, such that a plurality of base portions remain at the major surface, thereby forming an array of inverted truncated pyramid shapes;

depositing a first electrode on each of the base portions;

bonding each of the first electrodes to a second substrate;

removing the first substrate, thereby exposing a light emitting surface of the slab p-n junction; and

depositing a second electrode on the light emitting surface.

52. A method for pixelating an LED, comprising:

providing a slab p-n junction on a first substrate, the slab p-n junction including a major surface opposite the first substrate, and an emissive region parallel to the major surface;

selectively depositing a plurality of first electrodes on the major surface;

bonding each of the first electrodes to a second substrate;

removing the first substrate, thereby exposing a light emitting surface of the slab p-n junction;

selectively removing material from the light emitting surface to a depth of the major surface, such that a plurality of pixels remain at the light emitting surface, thereby forming an array of inverted truncated pyramid shapes; and

depositing a second electrode on the light emitting surface.