PHOTONIC CRYSTAL LED

• US 20100270572A1
• Filed: 12/12/2008
• Published: 10/28/2010
• Est. Priority Date: 12/18/2007
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Verschuuren, Marcus Antonius, Van Sprang, Hendrik Adrianus
• Granted Patent: US 8,536,600 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A semiconductor light emitting diode (1, LED), comprising a first and a second electrode (40, 11) for applying a voltage across an active region (4) for generation of light, a light emitting surface (6), and a plurality of photonic crystals (101, 102). Further, at least two photonic crystals (101, 102) of a first and a second type are adapted to extract light from the active region (4) and differ from each other with respect to at least one lattice parameter. Each of said at least two photonic crystals (101, 102) are associated with a respective far field pattern, wherein an arrangement of said plurality of photonic crystals (101, 102) is provided to arrange said at least two photonic crystals (101, 102). In this manner, a far field pattern is created by combining the respective far field patterns associated with each of said at least two photonic crystals (101, 102).

Claims

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

a first and a second electrode (40, 11) for applying a voltage across an active region (4), disposed between a first type semiconductor layer (21) and a second type semiconductor layer (30) for generation of light, a light emitting surface (6) for emitting said light, and a plurality of photonic crystals (101, 102) disposed between said light emitting surface (6) and said active region (4), characterized in that at least two photonic crystals (101, 102) of a first and a second type, selected among said plurality of photonic crystals (101, 102), are adapted to extract light from said active region (4) and differ from each other with respect to at least one lattice parameter, each of said at least two photonic crystals (101, 102) being associated with a respective far field pattern, wherein an arrangement of said plurality of photonic crystals (101, 102) is provided to arrange said at least two photonic crystals (101, 102), such that a far field pattern from the light generated in the LED (1) is created by combining said respective far field patterns associated with each of said at least two photonic crystals (101, 102).

2. The LED (1) according to claim 1, wherein said arrangement is arranged to position said at least two photonic crystals (101, 102) in a manner, such that irregularities of said respective far field patterns associated with each of said at least two photonic crystals are at least partly non-overlapping.

3. The LED (1) according to claim 1, wherein said at least one lattice parameter is one of lattice orientation, lattice pitch, lattice type or fill fraction or a combination thereof.

4. The LED (1) according to claim 1, wherein said lattice type comprises at least one of a hexagonal, triangular, cubic structure, sunflower structure or Archimedean tilings.

5. The LED (1) according to claim 1, wherein said first type semiconductor layer (21) is a N-type semiconductor layer, disposed between said active region (4) and said light emitting surface, and said second type semiconductor layer (30) is a P-type semiconductor layer, disposed on the opposite side of said active region (4) compared to said first type semiconductor layer (21).

6. The LED (1) according to claim 1, wherein said first type semiconductor layer (21) is a P-type semiconductor layer, disposed between said active region (4) and said light emitting surface (6), and said second type semiconductor layer (30) is a N-type semiconductor layer, disposed on the opposite side of said active region (4) compared to said first type semiconductor layer (21).

7. The LED (1) according to claim 1, wherein said photonic crystals comprise photonic quasi-crystals.

8. The LED 1 according to claim 1, wherein said light emitting surface (6) of said LED comprises roughened areas (R).

9. The LED (1) according to claim 1, wherein said photonic crystals (101, 102) are arranged adjacent to each other for continuously covering at least a portion of said light emitting surface (6) of said LED (1) with photonic crystals (101, 102, 103).

10. The LED (1) according to claim 1, wherein said second electrode comprises sub-electrodes, disposed on the opposite side of said active region compared to said light emitting surface, wherein a first and a second sub-electrode are associated with a respective photonic crystal of the first and second type, respectively, said first and second sub-electrodes being individually controllable by means of applying a respective voltage to each of said first and second sub-electrodes, whereby the far field pattern of said LED is dynamically controllable due to difference between far field patterns from said photonic crystals of a first and a second type.

11. The LED (1) according to claim 10, wherein the size and shape of said sub-electrodes (41-45) matches the size and shape of said respective photonic crystal (101, 102).

12. The LED (1) according to claim 10, wherein each sub-electrode (41-45) is aligned with said respective photonic crystal (101, 102).

13. The LED (1) according to claim 10, wherein said second type semiconductor layer (30), disposed on the opposite side of said active region (4) compared to said light emitting surface (6), is divided into sub-elements, each sub-element being associated with a corresponding sub-electrode.

14. The LED (1) according to claim 10, wherein said light emitting surface comprises at least one of micro-lenses, colored areas, luminescent material covered areas or a combination thereof.