Photonic crystal light emitting device
View Patent ↗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.
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.