Photonic Crystal Light Emitting Device

• US 20090045427A1
• Filed: 10/27/2008
• Published: 02/19/2009
• Est. Priority Date: 03/19/2004
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.), Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Krames, Michael R., Epler, John E., Wierer, Jonathan J. JR.
• Granted Patent: US 7,675,084 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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 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 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• 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 photonic crystal structure is formed in an n-type region of a III-nitride semiconductor structure including an active region sandwiched between an n-type region and a p-type region. A reflector is formed on a surface of the p-type region opposite the active region. In some embodiments, the growth substrate on which the n-type region, active region, and p-type region are grown is removed, in order to facilitate forming the photonic crystal in an n-type region of the device, and to facilitate forming the reflector on a surface of the p-type region underlying the photonic crystal. The photonic crystal and reflector form a resonant cavity, which may allow control of light emitted by the active region.

Claims

1. A device comprising:

a III-nitride semiconductor structure including an active region disposed between a first n-type region and a p-type region;

a photonic crystal structure disposed in at least a portion of the first n-type region;

a second n-type region disposed between the photonic crystal structure and the active region; and

a reflector disposed on at least a portion of a surface of the p-type region opposite the active region;

wherein a top surface and a bottom surface of a structure comprising all semiconductor layers in the device are uninterrupted by the photonic crystal structure.

2. The device of claim 1 wherein a majority of light emitted by the active region that exits the semiconductor structure exits through a surface of the semiconductor structure opposite the surface on which the reflector is disposed.

3. The device of claim 1 further comprising a first contact electrically connected to one of the first and second n-type regions and a second contact electrically connected to the p-type region, wherein the first and second contacts are disposed on the same side of the semiconductor structure.

4. The device of claim 3 wherein one of the first and second contacts is reflective.

5. The device of claim 3 wherein the second contact is reflective.

6. The device of claim 3 wherein the second contact comprises Ag.

7. The device of claim 3 further comprising at least one via extending through the p-type region and the active region to one of the first and second n-type regions, wherein the first contact is disposed within the via.

8. The device of claim 3 further comprising a material disposed between the first and second contacts.

9. The device of claim 8 wherein the material is a dielectric.

10. The device of claim 1 further comprising a first contact electrically connected to one of the first and second n-type regions and a second contact electrically connected to the p-type region, wherein the first and second contacts are disposed on opposite sides of the semiconductor structure.

11. The device of claim 1 wherein the photonic crystal structure comprises a planar lattice of holes.

12. The device of claim 11 wherein the planar lattice includes one or more lattice types selected from the group consisting of a triangular lattice, a square lattice, a hexagonal lattice, and a honeycomb lattice.

13. The device of claim 11 wherein a lattice type, lattice constant, hole diameter, and hole depth of the planar lattice of holes are selected to create a predetermined radiation pattern.

14. The device of claim 13 wherein greater than 50% of radiation exiting the semiconductor structure is emitted in an exit cone defined by an angle of 45 degrees to an axis normal to a surface of the semiconductor structure.