Pixelated LED

• US 9,196,653 B2
• Filed: 07/27/2010
• Issued: 11/24/2015
• Est. Priority Date: 07/30/2009
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Leatherdale, Catherine A., Yang, Zhaohui Zy
• Primary Examiner(s): Landau, Matthew
• Assistant Examiner(s): Anya, Igwe U
• Application Number:
  US13/384,347
• Publication Number:
  US 20120119237A1
• Time in Patent Office: 1,946 Days
• Field of Search: 257/88
• US Class Current: 1/1
• 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;

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

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; and

a color converter disposed adjacent the light emitting surface of each electroluminescent element,

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

2. 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.

3. The pixelated LED of claim 1, wherein each color converter comprises a potential well.

4. The pixelated LED of claim 3, wherein the potential well comprises a group II-VI or a group III-V semiconductor.

5. The pixelated LED of claim 1, wherein the emissive region is positioned closer to the first electrode than to the light emitting surface.

6. The pixelated LED of claim 5, wherein a distance between the emissive region and the first electrode ranges from about 150 nm to about 250 nm.

7. 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; and

a color converter disposed adjacent the first major light emitting surface of each electroluminescent element.

8. The pixelated LED of claim 7, 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.

9. The pixelated LED of claim 7, wherein each p-n junction comprises a quantum well positioned closer to the second major surface than to the first major light emitting surface.

10. The pixelated LED of claim 9, wherein a distance between the quantum well and the second major surface from about 150 nm to about 250 nm.

11. The pixelated LED of claim 7, wherein an angle between the substrate and a side of each electroluminescent element ranges from about 35 degrees to about 70 degrees.

12. The pixelated LED of claim 7, wherein each color converter comprises a potential well.

13. The pixelated LED of claim 12, wherein the potential well comprises a group II-VI or a group III-V semiconductor.