Reflective layer between light-emitting diodes

• US 8,716,723 B2
• Filed: 11/13/2008
• Issued: 05/06/2014
• Est. Priority Date: 08/18/2008
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: TSMC Solid State Lighting Ltd. (Ennostar, Inc.)
• Inventors: Chen, Ding-Yuan, Yu, Chia-Lin, Yu, Chen-Hua, Chiou, Wen-Chih
• Primary Examiner(s): Rizkallah, Kimberly
• Assistant Examiner(s): HENRY, CALEB E
• Application Number:
  US12/270,309
• Publication Number:
  US 20100038655A1
• Time in Patent Office: 2,000 Days
• Field of Search: 257/88, 257/98, 257/44, 257/E33.067, 438/29
• US Class Current: 257/88
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• 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
• CPC Class Codes: H01L 33/42 Transparent materials
• 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

A system and method for manufacturing a light-generating device is described. A preferred embodiment comprises a plurality of LEDs formed on a substrate. Each LED preferably has spacers along the sidewalls of the LED, and a reflective surface is formed on the substrate between the LEDs. The reflective surface is preferably located lower than the active layer of the individual LEDs.

Claims

1. A light-generating device comprising:

a substrate;

a first light-emitting diode on the substrate, the first light-emitting diode comprising a first active layer;

a second light-emitting diode on the substrate, the second light-emitting diode comprising a second active layer;

a top electrode electrically coupling together the first light-emitting diode and the second light-emitting diode; and

a reflective layer located over the substrate between the first light-emitting diode and the second light-emitting diode, the reflective layer being laterally separated from the first light-emitting diode by a spacer, the reflective layer comprising a top surface closer to the substrate than the first active layer, wherein a bottom surface of the reflective layer is in direct contact with the substrate and is substantially co-planar with at least one of the first light-emitting diode and the second light-emitting diode.

2. The light-generating device of claim 1, wherein the reflective layer comprises aluminum, silver, or other reflective materials.

3. The light-emitting device of claim 1, wherein the first light-emitting diode is configured to emit a light with a first wavelength and a width of the first light-emitting diode is between about 0.3 to about 3 times the first wavelength.

4. The light-generating device of claim 1, further comprising spacers located along sidewalls of the first light-emitting diode.

5. The light-generating device of claim 1, wherein the substrate is a light absorbing substrate.

6. The light-generating device of claim 1, further comprising a light-transmissive material over the reflective layer between the first light-emitting diode and the second light-emitting diode.

7. A light-generating device comprising:

a substrate;

a reflector over portions of the substrate, the reflector having a first thickness;

a plurality of light-emitting diodes extending through the reflector to the substrate, each of the plurality of light-emitting diodes being isolated from the reflector and comprising an active layer that is located a first distance from the substrate, the first distance being greater than the first thickness, wherein a bottom surface of the reflector is substantially co-planar with a bottom surface of at least one of the light-emitting diodes, and wherein the light-emitting diodes are electrically coupled together through a top electrode; and

a light-transmissive material over the reflector between adjacent ones of the plurality of light-emitting diodes.

8. The light-generating device of claim 7, wherein the reflective layer comprises aluminum, silver, or other reflective materials.

9. The light-generating device of claim 7, wherein at least one of the plurality of light-emitting diodes has a width that is between about 0.3 to about 3 times a wavelength of light emitted by the light-generating device.

10. The light-generating device of claim 7, further comprising spacers located along sidewalls of the plurality of light-emitting diodes.

11. The light-generating device of claim 7, wherein the substrate is a light-absorbing substrate.

12. The light-generating device of claim 7, wherein each of the plurality of light-emitting diodes is in the shape of a circle, a rectangle, an ellipse, a triangle, or a hexagon.

13. The light-generating device of claim 7, wherein the reflector is in physical contact with the substrate.

14. A light-generating device comprising:

a first light-emitting device and a second light-emitting device located on a substrate;

a top electrode electrically coupling the first light-emitting device to the second light-emitting device;

a reflective layer located between the first light-emitting device and the second light-emitting device, the reflective layer located to reflect light from the first light-emitting device and from the second light-emitting device away from the substrate, wherein a bottom surface of the reflective layer is substantially co-planar with a bottom surface of at least one of the first light-emitting device and the second light-emitting device; and

a plurality of spacers located between the first light-emitting device and the reflective layer and between the first and second light-emitting devices, the plurality of spacers isolating the first and second light-emitting devices from the reflective layer, wherein each of the plurality of spacers has different widths at different distances from the substrate.

15. The light-generating device of claim 14, wherein the reflective layer comprises aluminum, silver, or other reflective materials.

16. The light-generating device of claim 14, wherein the substrate is a light absorbing substrate.

17. The light-generating device of claim 14, further comprising a light-transmissive material over the reflective layer between the first light-emitting diode and the second light-emitting diode.

18. The light-generating device of claim 14, wherein the first light-emitting diode is in the shape of a circle, a rectangle, an ellipse, a triangle or a hexagon.

19. The light-generating device of claim 14, wherein the spacer has a width that expands as the spacer gets closer to the substrate.

20. The light-generating device of claim 14, further comprising an electrode located over the first light-emitting device and the second light-emitting device.